Science.gov

Sample records for aperture radar images

  1. Imaging synthetic aperture radar

    DOEpatents

    Burns, Bryan L.; Cordaro, J. Thomas

    1997-01-01

    A linear-FM SAR imaging radar method and apparatus to produce a real-time image by first arranging the returned signals into a plurality of subaperture arrays, the columns of each subaperture array having samples of dechirped baseband pulses, and further including a processing of each subaperture array to obtain coarse-resolution in azimuth, then fine-resolution in range, and lastly, to combine the processed subapertures to obtain the final fine-resolution in azimuth. Greater efficiency is achieved because both the transmitted signal and a local oscillator signal mixed with the returned signal can be varied on a pulse-to-pulse basis as a function of radar motion. Moreover, a novel circuit can adjust the sampling location and the A/D sample rate of the combined dechirped baseband signal which greatly reduces processing time and hardware. The processing steps include implementing a window function, stabilizing either a central reference point and/or all other points of a subaperture with respect to doppler frequency and/or range as a function of radar motion, sorting and compressing the signals using a standard fourier transforms. The stabilization of each processing part is accomplished with vector multiplication using waveforms generated as a function of radar motion wherein these waveforms may be synthesized in integrated circuits. Stabilization of range migration as a function of doppler frequency by simple vector multiplication is a particularly useful feature of the invention; as is stabilization of azimuth migration by correcting for spatially varying phase errors prior to the application of an autofocus process.

  2. Nonlinear synthetic aperture radar imaging using a harmonic radar

    NASA Astrophysics Data System (ADS)

    Gallagher, Kyle A.; Mazzaro, Gregory J.; Ranney, Kenneth I.; Nguyen, Lam H.; Martone, Anthony F.; Sherbondy, Kelly D.; Narayanan, Ram M.

    2015-05-01

    This paper presents synthetic aperture radar (SAR) images of linear and nonlinear targets. Data are collected using a linear/nonlinear step frequency radar. We show that it is indeed possible to produce SAR images using a nonlinear radar. Furthermore, it is shown that the nonlinear radar is able to reduce linear clutter by at least 80 dB compared to a linear radar. The nonlinear SAR images also show the system's ability to detect small electronic devices in the presence of large linear clutter. The system presented here has the ability to completely ignore a 20-inch trihedral corner reflector while detecting a RF mixer with a dipole antenna attached.

  3. Triangulation using synthetic aperture radar images

    NASA Technical Reports Server (NTRS)

    Wu, Sherman S. C.; Howington-Kraus, Annie E.

    1991-01-01

    For the extraction of topographic information about Venus from stereoradar images obtained from the Magellan Mission, a Synthetic Aperture Radar (SAR) compilation system was developed on analytical stereoplotters. The system software was extensively tested by using stereoradar images from various spacecraft and airborne radar systems, including Seasat, SIR-B, ERIM XCL, and STAR-1. Stereomodeling from radar images was proven feasible, and development is on a correct approach. During testing, the software was enhanced and modified to obtain more flexibility and better precision. Triangulation software for establishing control points by using SAR images was also developed through a joint effort with the Defense Mapping Agency. The SAR triangulation system comprises four main programs, TRIDATA, MODDATA, TRISAR, and SHEAR. The first two programs are used to sort and update the data; the third program, the main one, performs iterative statistical adjustment; and the fourth program analyzes the results. Also, input are flight data and data from the Global Positioning System and Inertial System (navigation information). The SAR triangulation system was tested with six strips of STAR-1 radar images on a VAX-750 computer. Each strip contains images of 10 minutes flight time (equivalent to a ground distance of 73.5 km); the images cover a ground width of 22.5 km. All images were collected from the same side. With an input of 44 primary control points, 441 ground control points were produced. The adjustment process converged after eight iterations. With a 6-m/pixel resolution of the radar images, the triangulation adjustment has an average standard elevation error of 81 m. Development of Magellan radargrammetry will be continued to convert both SAR compilation and triangulation systems into digital form.

  4. Stereoscopic Height Estimation from Multiple Aspect Synthetic Aperture Radar Images

    SciTech Connect

    DELAURENTIS,JOHN M.; DOERRY,ARMIN W.

    2001-08-01

    A Synthetic Aperture Radar (SAR) image is a two-dimensional projection of the radar reflectivity from a 3-dimensional object or scene. Stereoscopic SAR employs two SAR images from distinct flight paths that can be processed together to extract information of the third collapsed dimension (typically height) with some degree of accuracy. However, more than two SAR images of the same scene can similarly be processed to further improve height accuracy, and hence 3-dimensional position accuracy. This report shows how.

  5. Synthetic Aperture Radar Image Formation in Reconfigurable Logic

    SciTech Connect

    DUDLEY,PETER A.

    2001-06-01

    This paper studies the implementation of polar format, synthetic aperture radar image formation in modern Field Programmable Gate Arrays (FPGA's). The polar format algorithm is described in rough terms and each of the processing steps is mapped to FPGA logic. This FPGA logic is analyzed with respect to throughput and circuit size for compatibility with airborne image formation.

  6. Practical synthetic aperture radar image formation based on realistic spaceborne synthetic aperture radar modeling and simulation

    NASA Astrophysics Data System (ADS)

    Shim, Sang Heun; Ro, Yong Man

    2013-01-01

    This paper presents the practical spaceborne synthetic aperture radar (SAR) data focusing method based on the realistic end-to-end spaceborne SAR simulation. Our simulation reflects main factors of the satellite SAR that induce errors to degrade the focused image severely, which are related to the sensor hardware, the antenna beam pointing, the effective velocity, and the Doppler frequency. To minimize errors due to them in the spaceborne SAR image formation, we suggest and utilize the preprocessing as the internal calibration, the analysis of orbital data of an SAR satellite, the calculation of an effective velocity and the Doppler frequency utilizing the two-way slant range equation, and the usage of the phase gradient algorithm combined with the extended chirp scaling algorithm based on the azimuth signal deramping. The processing results for realistic simulated raw data of a spaceborne SAR are presented to validate the proposed methods.

  7. Image simulation of geometric targets for synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Nasr, J. M.

    1989-10-01

    A new technique for image simulation which comes from a synthetic aperture radar is presented. The method is based on the embedding of an artificially simulated target in a real radar image captured by an operational antenna window on a satellite (SEASAT or SIR-B). A L and C band was used for the capture. The target dimensions studied were large enough for use with long waves provided the calculation techniques used with high frequencies were for an equivalent area radar (SER). The calculation of SER allows the capture of a raw signal received from the antennas. So that the possibility of simulation is low, some restrictions are made. The results are sufficiently interesting enough to let the study of the behavior of a particular target become of use to civilians or the military, in the functional bounds of radar waves.

  8. Synthetic aperture radar/LANDSAT MSS image registration

    NASA Technical Reports Server (NTRS)

    Maurer, H. E. (Editor); Oberholtzer, J. D. (Editor); Anuta, P. E. (Editor)

    1979-01-01

    Algorithms and procedures necessary to merge aircraft synthetic aperture radar (SAR) and LANDSAT multispectral scanner (MSS) imagery were determined. The design of a SAR/LANDSAT data merging system was developed. Aircraft SAR images were registered to the corresponding LANDSAT MSS scenes and were the subject of experimental investigations. Results indicate that the registration of SAR imagery with LANDSAT MSS imagery is feasible from a technical viewpoint, and useful from an information-content viewpoint.

  9. Passive synthetic aperture radar imaging of ground moving targets

    NASA Astrophysics Data System (ADS)

    Wacks, Steven; Yazici, Birsen

    2012-05-01

    In this paper we present a method for imaging ground moving targets using passive synthetic aperture radar. A passive radar imaging system uses small, mobile receivers that do not radiate any energy. For these reasons, passive imaging systems result in signicant cost, manufacturing, and stealth advantages. The received signals are obtained by multiple airborne receivers collecting scattered waves due to illuminating sources of opportunity such as commercial television, radio, and cell phone towers. We describe a novel forward model and a corresponding ltered-backprojection type image reconstruction method combined with entropy optimization. Our method determines the location and velocity of multiple targets moving at dierent velocities. Furthermore, it can accommodate arbitrary imaging geometries. we present numerical simulations to verify the imaging method.

  10. Remote sensing with spaceborne synthetic aperture imaging radars: A review

    NASA Technical Reports Server (NTRS)

    Cimino, J. B.; Elachi, C.

    1983-01-01

    A review is given of remote sensing with Spaceborne Synthetic Aperture Radars (SAR's). In 1978, a spaceborne SA was flown on the SEASAT satellite. It acquired high resulution images over many regions in North America and the North Pacific. The acquired data clearly demonstrate the capability of spaceborne SARs to: image and track polar ice floes; image ocean surface patterns including swells, internal waves, current boundaries, weather boundaries and vessels; and image land features which are used to acquire information about the surface geology and land cover. In 1981, another SAR was flown on the second shuttle flight. This Shuttle Imaging Radar (SIR-A) acquired land and ocean images over many areas around the world. The emphasis of the SIR-A experiment was mainly toward geologic mapping. Some of the key results of the SIR-A experiment are given.

  11. Optimum frequency for subsurface-imaging synthetic-aperture radar

    SciTech Connect

    Brock, B.C.; Patitz, W.E.

    1993-05-01

    A subsurface-imaging synthetic-aperture radar (SISAR) has potential for application in areas as diverse as non-proliferation programs for nuclear weapons to environmental monitoring. However, most conventional synthetic-aperture radars operate at higher microwave frequencies which do not significantly penetrate below the soil surface. This study attempts to provide a basis for determining optimum frequencies and frequency ranges which will allow synthetic-aperture imaging of buried targets. Since the radar return from a buried object must compete with the return from surface clutter, the signal-to-clutter ratio is an appropriate measure of performance for a SISAR. A parameter-based modeling approach is used to model the complex dielectric constant of the soil from measured data obtained from the literature. Theoretical random-surface scattering models, based on statistical solutions to Maxwell`s equations, are used to model the clutter. These models are combined to estimate the signal-to-clutter ratio for canonical targets buried in several soil configurations. Initial results indicate that the HF spectrum (3--30 MHz), although it could be used to detect certain targets under some conditions, has limited practical value for use with SISAR, while the upper vhf through uhf spectrum ({approximately}100 MHz--1 GHz) shows the most promise for a general purpose SISAR system. Recommendations are included for additional research.

  12. Optimum frequency for subsurface-imaging synthetic-aperture radar

    SciTech Connect

    Brock, B.C.; Patitz, W.E.

    1993-05-01

    A subsurface-imaging synthetic-aperture radar (SISAR) has potential for application in areas as diverse as non-proliferation programs for nuclear weapons to environmental monitoring. However, most conventional synthetic-aperture radars operate at higher microwave frequencies which do not significantly penetrate below the soil surface. This study attempts to provide a basis for determining optimum frequencies and frequency ranges which will allow synthetic-aperture imaging of buried targets. Since the radar return from a buried object must compete with the return from surface clutter, the signal-to-clutter ratio is an appropriate measure of performance for a SISAR. A parameter-based modeling approach is used to model the complex dielectric constant of the soil from measured data obtained from the literature. Theoretical random-surface scattering models, based on statistical solutions to Maxwell's equations, are used to model the clutter. These models are combined to estimate the signal-to-clutter ratio for canonical targets buried in several soil configurations. Initial results indicate that the HF spectrum (3--30 MHz), although it could be used to detect certain targets under some conditions, has limited practical value for use with SISAR, while the upper vhf through uhf spectrum ([approximately]100 MHz--1 GHz) shows the most promise for a general purpose SISAR system. Recommendations are included for additional research.

  13. A comparison of spotlight synthetic aperture radar image formation techniques

    SciTech Connect

    Knittle, C.D.; Doren, N.E.; Jakowatz, C.V.

    1996-10-01

    Spotlight synthetic aperture radar images can be formed from the complex phase history data using two main techniques: (1) polar-to-cartesian interpolation followed by two-dimensional inverse Fourier transform (2DFFT), and (2) convolution backprojection (CBP). CBP has been widely used to reconstruct medical images in computer aided tomography, and only recently has been applied to form synthetic aperture radar imagery. It is alleged that CBP yields higher quality images because (1) all the Fourier data are used and (2) the polar formatted data is used directly to form a 2D Cartesian image and therefore 2D interpolation is not required. This report compares the quality of images formed by CBP and several modified versions of the 2DFFT method. We show from an image quality point of view that CBP is equivalent to first windowing the phase history data and then interpolating to an exscribed rectangle. From a mathematical perspective, we should expect this conclusion since the same Fourier data are used to form the SAR image. We next address the issue of parallel implementation of each algorithm. We dispute previous claims that CBP is more readily parallelizable than the 2DFFT method. Our conclusions are supported by comparing execution times between massively parallel implementations of both algorithms, showing that both experience similar decreases in computation time, but that CBP takes significantly longer to form an image.

  14. Synthetic aperture radar images with composite azimuth resolution

    DOEpatents

    Bielek, Timothy P; Bickel, Douglas L

    2015-03-31

    A synthetic aperture radar (SAR) image is produced by using all phase histories of a set of phase histories to produce a first pixel array having a first azimuth resolution, and using less than all phase histories of the set to produce a second pixel array having a second azimuth resolution that is coarser than the first azimuth resolution. The first and second pixel arrays are combined to produce a third pixel array defining a desired SAR image that shows distinct shadows of moving objects while preserving detail in stationary background clutter.

  15. Apodized RFI filtering of synthetic aperture radar images

    SciTech Connect

    Doerry, Armin Walter

    2014-02-01

    Fine resolution Synthetic Aperture Radar (SAR) systems necessarily require wide bandwidths that often overlap spectrum utilized by other wireless services. These other emitters pose a source of Radio Frequency Interference (RFI) to the SAR echo signals that degrades SAR image quality. Filtering, or excising, the offending spectral contaminants will mitigate the interference, but at a cost of often degrading the SAR image in other ways, notably by raising offensive sidelobe levels. This report proposes borrowing an idea from nonlinear sidelobe apodization techniques to suppress interference without the attendant increase in sidelobe levels. The simple post-processing technique is termed Apodized RFI Filtering (ARF).

  16. Semisupervised synthetic aperture radar image segmentation with multilayer superpixels

    NASA Astrophysics Data System (ADS)

    Wang, Can; Su, Weimin; Gu, Hong; Gong, Dachen

    2015-01-01

    Image segmentation plays a significant role in synthetic aperture radar (SAR) image processing. However, SAR image segmentation is challenging due to speckle. We propose a semisupervised bipartite graph method for segmentation of an SAR image. First, the multilayer over-segmentation of the SAR image, referred to as superpixels, is computed using existing segmentation algorithms. Second, an unbalanced bipartite graph is constructed in which the correlation between pixels is replaced by the texture similarity between superpixels, to reduce the dimension of the edge matrix. To also improve efficiency, we define a new method, called the combination of the Manhattan distance and symmetric Kullback-Leibler divergence, to measure texture similarity. Third, by the Moore-Penrose inverse matrix and semisupervised learning, we construct an across-affinity matrix. A quantitative evaluation using SAR images shows that the new algorithm produces significantly high-quality segmentations as compared with state-of-the-art segmentation algorithms.

  17. Logarithmic Laplacian Prior Based Bayesian Inverse Synthetic Aperture Radar Imaging

    PubMed Central

    Zhang, Shuanghui; Liu, Yongxiang; Li, Xiang; Bi, Guoan

    2016-01-01

    This paper presents a novel Inverse Synthetic Aperture Radar Imaging (ISAR) algorithm based on a new sparse prior, known as the logarithmic Laplacian prior. The newly proposed logarithmic Laplacian prior has a narrower main lobe with higher tail values than the Laplacian prior, which helps to achieve performance improvement on sparse representation. The logarithmic Laplacian prior is used for ISAR imaging within the Bayesian framework to achieve better focused radar image. In the proposed method of ISAR imaging, the phase errors are jointly estimated based on the minimum entropy criterion to accomplish autofocusing. The maximum a posterior (MAP) estimation and the maximum likelihood estimation (MLE) are utilized to estimate the model parameters to avoid manually tuning process. Additionally, the fast Fourier Transform (FFT) and Hadamard product are used to minimize the required computational efficiency. Experimental results based on both simulated and measured data validate that the proposed algorithm outperforms the traditional sparse ISAR imaging algorithms in terms of resolution improvement and noise suppression. PMID:27136551

  18. Logarithmic Laplacian Prior Based Bayesian Inverse Synthetic Aperture Radar Imaging.

    PubMed

    Zhang, Shuanghui; Liu, Yongxiang; Li, Xiang; Bi, Guoan

    2016-01-01

    This paper presents a novel Inverse Synthetic Aperture Radar Imaging (ISAR) algorithm based on a new sparse prior, known as the logarithmic Laplacian prior. The newly proposed logarithmic Laplacian prior has a narrower main lobe with higher tail values than the Laplacian prior, which helps to achieve performance improvement on sparse representation. The logarithmic Laplacian prior is used for ISAR imaging within the Bayesian framework to achieve better focused radar image. In the proposed method of ISAR imaging, the phase errors are jointly estimated based on the minimum entropy criterion to accomplish autofocusing. The maximum a posterior (MAP) estimation and the maximum likelihood estimation (MLE) are utilized to estimate the model parameters to avoid manually tuning process. Additionally, the fast Fourier Transform (FFT) and Hadamard product are used to minimize the required computational efficiency. Experimental results based on both simulated and measured data validate that the proposed algorithm outperforms the traditional sparse ISAR imaging algorithms in terms of resolution improvement and noise suppression. PMID:27136551

  19. Gulf Stream surface convergence imaged by synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Marmorino, G. O.; Jansen, R. W.; Valenzuela, G. R.; Trump, C. L.; Lee, J. S.; Kaiser, J. A. C.

    1994-09-01

    On July 20, 1990, the north edge of the Gulf Stream (36.7°N, 72.0°W) was sampled by the R/V Cape Henlopen and simultaneously imaged by the Jet Propulsion Laboratory's airborne synthetic aperture radar (SAR). Hydrographic measurements show an abrupt surface front separating warm, salty Gulf Stream water in the south from a filament of cool, fresh (<33 practical salinity unit (psu)) water to the north. The filament lies within the stream and is likely water entrained from the continental shelf. The southern boundary of the filament is marked by increased surface wave breaking in a 100- to 200-m-wide zone, accumulations of Sargassum, and an orthogonal velocity change of 20 cm/s. The front is manifested in a sequence of SAR images as a narrow line having returns 1-2 dB higher than background. (A second, transient SAR line occurs near the northern filament boundary.) The observations are compared with model calculations of the surface wave hydrodynamics and radar scattering. The ocean waves are driven by southwesterly 8-m/s winds and interact with the front to produce primarily an enhancement of 2- to 3-m waves over a ≲200-m-wide region centered downwind of the front. Using a composite scattering radar model along with measured breaking-wave statistics, we show that the observed modulations in the radar backscatter can be accounted for through breaking-wave and tilted Bragg wave scattering effects. These results further show that SAR images of the ocean surface can be exploited for detailed study of particular ocean processes.

  20. Hierarchical model-based interferometric synthetic aperture radar image registration

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Huang, Haifeng; Dong, Zhen; Wu, Manqing

    2014-01-01

    With the rapid development of spaceborne interferometric synthetic aperture radar technology, classical image registration methods are incompetent for high-efficiency and high-accuracy masses of real data processing. Based on this fact, we propose a new method. This method consists of two steps: coarse registration that is realized by cross-correlation algorithm and fine registration that is realized by hierarchical model-based algorithm. Hierarchical model-based algorithm is a high-efficiency optimization algorithm. The key features of this algorithm are a global model that constrains the overall structure of the motion estimated, a local model that is used in the estimation process, and a coarse-to-fine refinement strategy. Experimental results from different kinds of simulated and real data have confirmed that the proposed method is very fast and has high accuracy. Comparing with a conventional cross-correlation method, the proposed method provides markedly improved performance.

  1. Three-dimensional subsurface imaging synthetic aperture radar

    SciTech Connect

    Moussally, G.J.

    1995-03-01

    The objective of this applied research and development project is to develop a system known as `3-D SISAR`. This system consists of a ground penetrating radar with software algorithms designed for the detection, location, and identification of buried objects in the underground hazardous waste environments found at DOE storage sites. Three-dimensional maps of the object locations will be produced which can assist the development of remediation strategies and the characterization of the digface during remediation operations. It is expected that the 3-D SISAR will also prove useful for monitoring hydrocarbon based contaminant migration after remediation. The underground imaging technique being developed under this contract utilizes a spotlight mode Synthetic Aperture Radar (SAR) approach which, due to its inherent stand-off capability, will permit the rapid survey of a site and achieve a high degree of productivity over large areas. When deployed from an airborne platform, the stand-off techniques is also seen as a way to overcome practical survey limitations encountered at vegetated sites.

  2. The information content of synthetic aperture radar images of terrain

    NASA Technical Reports Server (NTRS)

    Frost, V. S.; Shanmugan, K. S.

    1983-01-01

    A statistical model is developed that portrays an imaging radar as a noisy communication channel with multiplicative noise, and the model is used to evaluate the average amount of information that can be extracted about a target from its radar image. The average information content is also used to define a measure of radiometric resolution for radar images. It is shown that the information content and the resolution capabilities of an imaging radar reach a limit beyond which an increase in scene dynamic range does not improve the information content or the resolution. This limitation results from the multiplicative nature of the noise introduced in the imaging process.

  3. Synthetic Aperture Radar Interferometry

    NASA Technical Reports Server (NTRS)

    Rosen, P. A.; Hensley, S.; Joughin, I. R.; Li, F.; Madsen, S. N.; Rodriguez, E.; Goldstein, R. M.

    1998-01-01

    Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristics of the surface. This paper reviews the techniques of interferometry, systems and limitations, and applications in a rapidly growing area of science and engineering.

  4. Model-supported exploitation of synthetic aperture radar images

    NASA Astrophysics Data System (ADS)

    Chellappa, Rama; Kuttikkad, Shyam; Meth, Reuven; Burlina, Philippe; Shekhar, Chandra S.

    1996-02-01

    We address the application of model-supported exploitation techniques to synthetic aperture radar (SAR) imagery. The emphasis is on monitoring SAR imagery using wide area 2D and/or 3D site models along with contextual information. We consider here the following tasks useful in monitoring: (a) site model construction using segmentation and labeling techniques, (b) target detection, (c) target classification and indexing, and (d) SAR image-site model registration. The 2-D wide area site models used here for SAR image exploitation differ from typical site models developed for RADIUS applications, in that they do not model specific facilities, but constitute wide area site models of cultural features such as urban clutter areas, roads, clearings, fields, etc. These models may be derived directly from existing site models, possibly constructed from electro-optical (EO) observations. When such models are not available, a set of segmentation and labeling techniques described here can be used for the construction of 2D site models. The use of models can potentially yield critical information which can disambiguate target signatures in SAR images. We address registration of SAR and EO images to a common site model. Specific derivations are given for the case of registration within the RCDE platform. We suggest a constant false alarm rate (CFAR) detection scheme and a topographic primal sketch (TPS) based classification scheme for monitoring target occurrences in SAR images. The TPS of an observed target is matched against candidate targets TPSs synthesized for the preferred target orientation, inferred from context (e.g. road or parking lot targets). Experimental results on real and synthetic SAR images are provided.

  5. Moving target imaging using ultrawideband synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Guo, Hanwei; Liang, Diannong; Wan, Yan; Huang, Xiaotao; Dong, Zhen

    2003-09-01

    Moving Target High Resolution Imaging of Foliage Penetrate Ultra-Wide Band Synthetic Aperture Radar (FOPEN UWB SAR) is of great significance for battlefield awareness of concealed target. Great range migration and strong clutter make moving target detection and imaging difficult, especially the Signal to Clutter Ration(SCR) some times is so low that the moving targets is invisible in FOPEN UWB SAR imagery. To improve SCR, the clean technique is used in range compressed data domain. The clean technique and data reconstruction help single channel of FOPEN UWB SAR suppress strong tree clutter and stationary target signal from region of interest. A new definition called General Key-Stone Transform is given, which can correct any order of range migration. FOPEN UWB SAR has long integrated time. The plane and target moving in long time lead to complex range migration. To obtain high resolution imagery of moving target, General Key-Stone transform are applied to remove the range migration and realize multiple moving target data segment. Both General Key-Stone Transform and Clean Technique are applied in real data processing of FOPEN UWB SAR. The result shows that multiple moving targets in the trees are clearly detected and high resolution imagery is formed.

  6. Shuttle Imaging Radar-C mission operations - Technology test bed for Earth Observing System synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Trimble, J. P.; Collins, C. E.

    1992-01-01

    The mission operations for the Space Radar Lab (SRL), particularly in the areas of real-time replanning and science activity coordination, are presented. The two main components of SRL are the Shuttle Imaging Radar-C and the X-Band Synthetic Aperture Radar. The Earth Observing System SAR will be a multispectral, multipolarization radar satellite that will provide information over an entire decade, permitting scientists to monitor large-scale changes in the earth's environment over a long period of time.

  7. Terahertz inverse synthetic aperture radar imaging using self-mixing interferometry with a quantum cascade laser.

    PubMed

    Lui, H S; Taimre, T; Bertling, K; Lim, Y L; Dean, P; Khanna, S P; Lachab, M; Valavanis, A; Indjin, D; Linfield, E H; Davies, A G; Rakić, A D

    2014-05-01

    We propose a terahertz (THz)-frequency synthetic aperture radar imaging technique based on self-mixing (SM) interferometry, using a quantum cascade laser. A signal processing method is employed which extracts and exploits the radar-related information contained in the SM signals, enabling the creation of THz images with improved spatial resolution. We demonstrate this by imaging a standard resolution test target, achieving resolution beyond the diffraction limit. PMID:24784063

  8. Synthetic aperture radar images of ocean waves, theories of imaging physics and experimental tests

    NASA Technical Reports Server (NTRS)

    Vesecky, J. F.; Durden, S. L.; Smith, M. P.; Napolitano, D. A.

    1984-01-01

    The physical mechanism for the synthetic Aperture Radar (SAR) imaging of ocean waves is investigated through the use of analytical models. The models are tested by comparison with data sets from the SEASAT mission and airborne SAR's. Dominant ocean wavelengths from SAR estimates are biased towards longer wavelengths. The quasispecular scattering mechanism agrees with experimental data. The Doppler shift for ship wakes is that of the mean sea surface.

  9. Superresolution and Synthetic Aperture Radar

    SciTech Connect

    DICKEY,FRED M.; ROMERO,LOUIS; DOERRY,ARMIN W.

    2001-05-01

    Superresolution concepts offer the potential of resolution beyond the classical limit. This great promise has not generally been realized. In this study we investigate the potential application of superresolution concepts to synthetic aperture radar. The analytical basis for superresolution theory is discussed. The application of the concept to synthetic aperture radar is investigated as an operator inversion problem. Generally, the operator inversion problem is ill posed. A criterion for judging superresolution processing of an image is presented.

  10. Wavefront curvature limitations and compensation to polar format processing for synthetic aperture radar images.

    SciTech Connect

    Doerry, Armin Walter

    2006-01-01

    Limitations on focused scene size for the Polar Format Algorithm (PFA) for Synthetic Aperture Radar (SAR) image formation are derived. A post processing filtering technique for compensating the spatially variant blurring in the image is examined. Modifications to this technique to enhance its robustness are proposed.

  11. Basics of Polar-Format algorithm for processing Synthetic Aperture Radar images.

    SciTech Connect

    Doerry, Armin Walter

    2012-05-01

    The purpose of this report is to provide a background to Synthetic Aperture Radar (SAR) image formation using the Polar Format (PFA) processing algorithm. This is meant to be an aid to those tasked to implement real-time image formation using the Polar Format processing algorithm.

  12. A study of image quality for radar image processing. [synthetic aperture radar imagery

    NASA Technical Reports Server (NTRS)

    King, R. W.; Kaupp, V. H.; Waite, W. P.; Macdonald, H. C.

    1982-01-01

    Methods developed for image quality metrics are reviewed with focus on basic interpretation or recognition elements including: tone or color; shape; pattern; size; shadow; texture; site; association or context; and resolution. Seven metrics are believed to show promise as a way of characterizing the quality of an image: (1) the dynamic range of intensities in the displayed image; (2) the system signal-to-noise ratio; (3) the system spatial bandwidth or bandpass; (4) the system resolution or acutance; (5) the normalized-mean-square-error as a measure of geometric fidelity; (6) the perceptual mean square error; and (7) the radar threshold quality factor. Selective levels of degradation are being applied to simulated synthetic radar images to test the validity of these metrics.

  13. Special Issue on Results from Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (Sir-C/X-SAR): Foreword

    NASA Technical Reports Server (NTRS)

    Plaut, Jefferey J.

    1996-01-01

    The two flights of the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the Space Shuttle Endeavour represent a major advance in remote sensing technology for studies of planetary surfaces.

  14. Method for providing a polarization filter for processing synthetic aperture radar image data

    NASA Technical Reports Server (NTRS)

    Dubois, Pascale C. (Inventor); Vanzyl, Jakob J. (Inventor)

    1990-01-01

    A polarization filter can maximize the signal-to-noise ratio of a polarimetric synthetic aperture radar (SAR) and help discriminate between targets or enhance image features, e.g., enhance contrast between different types of target. The method disclosed is based on the Stokes matrix/ Stokes vector representation, so the targets of interest can be extended targets, and the method can also be applied to the case of bistatic polarimetric radars.

  15. IFP V4.0:a polar-reformatting image formation processor for synthetic aperture radar.

    SciTech Connect

    Eichel, Paul H.

    2005-09-01

    IFP V4.0 is the fourth generation of an extraordinarily powerful and flexible image formation processor for spotlight mode synthetic aperture radar. It has been successfully utilized in processing phase histories from numerous radars and has been instrumental in the development of many new capabilities for spotlight mode SAR. This document provides a brief history of the development of IFP, a full exposition of the signal processing steps involved, and a short user's manual for the software implementing this latest iteration.

  16. Internal wave observations made with an airborne synthetic aperture imaging radar

    NASA Technical Reports Server (NTRS)

    Elachi, C.; Apel, J. R.

    1976-01-01

    Synthetic aperture L-band radar flown aboard the NASA CV-990 has observed periodic striations on the ocean surface off the coast of Alaska which have been interpreted as tidally excited oceanic internal waves of less than 500 m length. These radar images are compared to photographic imagery of similar waves taken from Landsat 1. Both the radar and Landsat images reveal variations in reflectivity across each wave in a packet that range from low to high to normal. The variations point to the simultaneous existence of two mechanisms for the surface signatures of internal waves: roughening due to wave-current interactions, and smoothing due to slick formation.

  17. Synthetic aperture radar target detection, feature extraction, and image formation techniques

    NASA Technical Reports Server (NTRS)

    Li, Jian

    1994-01-01

    This report presents new algorithms for target detection, feature extraction, and image formation with the synthetic aperture radar (SAR) technology. For target detection, we consider target detection with SAR and coherent subtraction. We also study how the image false alarm rates are related to the target template false alarm rates when target templates are used for target detection. For feature extraction from SAR images, we present a computationally efficient eigenstructure-based 2D-MODE algorithm for two-dimensional frequency estimation. For SAR image formation, we present a robust parametric data model for estimating high resolution range signatures of radar targets and for forming high resolution SAR images.

  18. Registration of a synthetic aperture radar image to Thematic Mapper imagery for remote sensing applications

    NASA Technical Reports Server (NTRS)

    Yao, S. S.; Gilbert, J. R.

    1984-01-01

    Multiple Thematic Mapper multitemporal acquisitions from Landsat and one synthetic-aperture radar acquisition from Seasat have been precisely registered using Johnson Space Center registration processors. The registered images have been output in the Universal Transverse Mercator projection. The procedure to accomplish such disparate data processing tasks and the registration accuracy evaluation are discussed.

  19. Synthetic Aperture Radar Imaging on a Cuda-Enabled Mobile Platform

    NASA Astrophysics Data System (ADS)

    Fatica, M.; Philllips, E.

    2014-12-01

    This talk will present the details of a Synthetic Aperture Radar (SAR) imaging on the smallest CUDA-capable platform available, the Jetson TK1. The results indicate that GPU accelerated embedded platforms have considerable potential for this type of workload and in conjunction with low power consumption, light weight and standard programming tools, could open new horizons in the embedded space.

  20. A model for forming airborne synthetic aperture radar images of underground targets

    SciTech Connect

    Doerry, A.W.

    1994-01-01

    Synthetic Aperture Radar (SAR) from an airborne platform has been proposed for imaging targets beneath the earth`s surface. The propagation of the radar`s energy within the ground, however, is much different than in the earth`s atmosphere. The result is signal refraction, echo delay, propagation losses, dispersion, and volumetric scattering. These all combine to make SAR image formation from an airborne platform much more challenging than a surface imaging counterpart. This report treats the ground as a lossy dispersive half-space, and presents a model for the radar echo based on measurable parameters. The model is then used to explore various imaging schemes, and image properties. Dynamic range is discussed, as is the impact of loss on dynamic range. Modified window functions are proposed to mitigate effects of sidelobes of shallow targets overwhelming deeper targets.

  1. Special Phenomena of the Shadow Region in the High Resolution Synthetic Aperture Radar Image due to Synthetic Aperture

    NASA Astrophysics Data System (ADS)

    Zhang, Yueting; Ding, Chibiao; Chen, Hongzhen; Wang, Hongqi

    2012-10-01

    With the development of several High Resolution (HR) Synthetic Aperture Radar (SAR) systems, many special phenomena appear in the SAR image, especially for the SAR image with millimeter wave. We firmly believed that every detail in the SAR image should have its own special mechanisms and these details may provide some key clues for us to build up the frame work on understanding the SAR image. The synthetic aperture is one of the important particularities about SAR, and the radar is moving during the data is collected, which leads many special phenomena in the SAR image; one of these is the shadow with blurred boundary. In this work, the effect on the shadow region in the SAR image by synthetic aperture is expanded on. The blurred boundary of the shadow is analyzed using imaging formation theory, and the Quadratic Phase Errors (QPE) brought by the synthetic aperture progress is deduced for the first time, which builds up the relationship between the parameters of the shadow caster and the behavior of the shadow in the SAR image. It is found that the QPE is approximately a linear function of the height of the shadow caster. Furthermore, an approach for shadow enhancement based on height variant phase compensation is proposed and it could provide a better effect on shadow enhancement than the traditional technique called Fixed Focus Shadow Enhancement (FFSE), which is proved by theoretical analysis and experiments. Based on the analysis, some typical application of the shadow in SAR image is designed and some mini-SAR image with Ku-band is analyzed about the shadow region. It is expected that the work in this paper could be some helpful for the SAR image understanding and the microwave imaging with high resolution.

  2. Information extraction and transmission techniques for spaceborne synthetic aperture radar images

    NASA Technical Reports Server (NTRS)

    Frost, V. S.; Yurovsky, L.; Watson, E.; Townsend, K.; Gardner, S.; Boberg, D.; Watson, J.; Minden, G. J.; Shanmugan, K. S.

    1984-01-01

    Information extraction and transmission techniques for synthetic aperture radar (SAR) imagery were investigated. Four interrelated problems were addressed. An optimal tonal SAR image classification algorithm was developed and evaluated. A data compression technique was developed for SAR imagery which is simple and provides a 5:1 compression with acceptable image quality. An optimal textural edge detector was developed. Several SAR image enhancement algorithms have been proposed. The effectiveness of each algorithm was compared quantitatively.

  3. Numerical simulation of synthetic aperture radar image spectra for ocean waves

    NASA Technical Reports Server (NTRS)

    Lyzenga, D. R.

    1986-01-01

    A numerical model for predicting the synthetic aperture radar (SAR) image of a moving ocean surface is described, and results are presented for two SIR-B data sets collected off the coast of Chile. Wave height spectra measured by the NASA radar ocean wave spectrometer (ROWS) were used as inputs to this model, and results are compared with actual SIR-B image spectra from orbits 91 and 106. Additional parametric variations are presented to illustrate the effects of nonlinearities in the imaging process.

  4. User guide to the Magellan synthetic aperture radar images

    NASA Technical Reports Server (NTRS)

    Wall, Stephen D.; Mcconnell, Shannon L.; Leff, Craig E.; Austin, Richard S.; Beratan, Kathi K.; Rokey, Mark J.

    1995-01-01

    The Magellan radar-mapping mission collected a large amount of science and engineering data. Now available to the general scientific community, this data set can be overwhelming to someone who is unfamiliar with the mission. This user guide outlines the mission operations and data set so that someone working with the data can understand the mapping and data-processing techniques used in the mission. Radar-mapping parameters as well as data acquisition issues are discussed. In addition, this user guide provides information on how the data set is organized and where specific elements of the set can be located.

  5. Three-dimensional subsurface imaging Synthetic Aperture Radar

    SciTech Connect

    Wuenschel, E.

    1995-10-01

    This report describes the development of a system known as 3-D SISAR. This system consists of a ground penetrating radar with software algorithms designed for the detection, location, and identification of buried objects in the underground hazardous waste environments at DOE storage sites.

  6. Shuttle synthetic aperture radar implementation study, volume 1. [flight instrument and ground data processor system for collecting raw imaged radar data

    NASA Technical Reports Server (NTRS)

    Mehlis, J. G.

    1976-01-01

    Results of an implementation study for a synthetic aperture radar for the space shuttle orbiter are described. The overall effort was directed toward the determination of the feasibility and usefulness of a multifrequency, multipolarization imaging radar for the shuttle orbiter. The radar is intended for earth resource monitoring as well as oceanographic and marine studies.

  7. Three-dimensional, subsurface imaging synthetic aperture radar

    SciTech Connect

    Moussally, G.J.

    1994-11-01

    The objective of this applied research and devolpment project is to develop a system known as 3-D SISAR. This sytem consists of a gound penetrating radar with software algorithms designed for detection, location, and identification of buried objects in the underground hazardous waste environments found at US DOE storage sites. Three-dimensional maps can assist the development of remdiation strategies and characterization of the digface during remediation. The system should also be useful for monitoring hydrocarbon-based contaminant migration after remediation. 5 figs.

  8. Multibeam single frequency synthetic aperture radar processor for imaging separate range swaths

    NASA Technical Reports Server (NTRS)

    Jain, A. (Inventor)

    1982-01-01

    A single-frequency multibeam synthetic aperture radar for large swath imaging is disclosed. Each beam illuminates a separate ""footprint'' (i.e., range and azimuth interval). The distinct azimuth intervals for the separate beams produce a distinct Doppler frequency spectrum for each beam. After range correlation of raw data, an optical processor develops image data for the different beams by spatially separating the beams to place each beam of different Doppler frequency spectrum in a different location in the frequency plane as well as the imaging plane of the optical processor. Selection of a beam for imaging may be made in the frequency plane by adjusting the position of an aperture, or in the image plane by adjusting the position of a slit. The raw data may also be processed in digital form in an analogous manner.

  9. Complex phase error and motion estimation in synthetic aperture radar imaging

    NASA Astrophysics Data System (ADS)

    Soumekh, M.; Yang, H.

    1991-06-01

    Attention is given to a SAR wave equation-based system model that accurately represents the interaction of the impinging radar signal with the target to be imaged. The model is used to estimate the complex phase error across the synthesized aperture from the measured corrupted SAR data by combining the two wave equation models governing the collected SAR data at two temporal frequencies of the radar signal. The SAR system model shows that the motion of an object in a static scene results in coupled Doppler shifts in both the temporal frequency domain and the spatial frequency domain of the synthetic aperture. The velocity of the moving object is estimated through these two Doppler shifts. It is shown that once the dynamic target's velocity is known, its reconstruction can be formulated via a squint-mode SAR geometry with parameters that depend upon the dynamic target's velocity.

  10. Synthetic aperture radar imaging algorithm customized for programmable optronic processor in the application of full-scene synthetic aperture radar image formation

    NASA Astrophysics Data System (ADS)

    Sheng, Hui; Gao, Yesheng; Zhu, Bingqi; Wang, Kaizhi; Liu, Xingzhao

    2015-01-01

    With the high programmability of a spatial light modulator (SLM), a newly developed synthetic aperture radar (SAR) optronic processor is capable of focusing SAR data with different parameters. The embedded SLM, encoding SAR data into light signal in the processor, has a limited loading resolution of 1920×1080. When the dimension of processed SAR data increases to tens of thousands in either range or azimuth direction, SAR data should be input and focused block by block. And then, part of the imaging results is mosaicked to offer a full-scene SAR image. In squint mode, however, Doppler centroid will shift signal spectrum in the azimuth direction and make phase filters, loaded by another SLM, unable to cover the entire signal spectrum. It brings about a poor imaging result. Meanwhile, the imaging result, shifted away from the center of light output, will cause difficulties in subsequent image mosaic. We present an SAR image formation algorithm designed to solve these problems when processing SAR data of a large volume in low-squint case. It could not only obtain high-quality imaging results, but also optimize the subsequent process of image mosaic with optimal system cost and efficiency. Experimental results validate the performance of this proposed algorithm in optical full-scene SAR imaging.

  11. Interferometric synthetic aperture radar detection and estimation based 3D image reconstruction

    NASA Astrophysics Data System (ADS)

    Austin, Christian D.; Moses, Randolph L.

    2006-05-01

    This paper explores three-dimensional (3D) interferometric synthetic aperture radar (IFSAR) image reconstruction when multiple scattering centers and noise are present in a radar resolution cell. We introduce an IFSAR scattering model that accounts for both multiple scattering centers and noise. The problem of 3D image reconstruction is then posed as a multiple hypothesis detection and estimation problem; resolution cells containing a single scattering center are detected and the 3D location of these cells' pixels are estimated; all other pixels are rejected from the image. Detection and estimation statistics are derived using the multiple scattering center IFSAR model. A 3D image reconstruction algorithm using these statistics is then presented, and its performance is evaluated for a 3D reconstruction of a backhoe from noisy IFSAR data.

  12. Autofocus correction of excessive migration in synthetic aperture radar images.

    SciTech Connect

    Doerry, Armin Walter

    2004-09-01

    When residual range migration due to either real or apparent motion errors exceeds the range resolution, conventional autofocus algorithms fail. A new migration-correction autofocus algorithm has been developed that estimates the migration and applies phase and frequency corrections to properly focus the image.

  13. Synthetic aperture radar capabilities in development

    SciTech Connect

    Miller, M.

    1994-11-15

    The Imaging and Detection Program (IDP) within the Laser Program is currently developing an X-band Synthetic Aperture Radar (SAR) to support the Joint US/UK Radar Ocean Imaging Program. The radar system will be mounted in the program`s Airborne Experimental Test-Bed (AETB), where the initial mission is to image ocean surfaces and better understand the physics of low grazing angle backscatter. The Synthetic Aperture Radar presentation will discuss its overall functionality and a brief discussion on the AETB`s capabilities. Vital subsystems including radar, computer, navigation, antenna stabilization, and SAR focusing algorithms will be examined in more detail.

  14. Reducing scalloping in synthetic aperture radar images using a composite image transform

    NASA Astrophysics Data System (ADS)

    Landmark, Knut; Solberg, Anne H. S.

    2015-10-01

    In burst mode SAR imaging, echo intensity depends on the target's azimuth position in the antenna pattern. As a result, an amplitude modulation known as scalloping may appear, particularly in ScanSAR images of ocean areas. A denoising method, recently developed for multibeam bathymetry, can be used to reduce residual scalloping in ScanSAR images. The algorithm is analogous to a band-stop filter in the frequency domain. Here, the transform is the composition of an edge detection operator and a discrete Radon transform (DRT). The edge operator accentuates fine-scale intensity changes; the DRT focuses linear features, as each DRT component is the sum of pixel intensities along a linear graph. A descalloping filter is implemented in the DRT domain by suppressing the range direction. The restored image is obtained by applying the inverse composite transform. First, a rapidly converging iterative pseudo-inverse DRT is computed. The edge operator is a spatial filter based on a discrete approximation of the Laplace operator, but modified to make the operator invertible. The method was tested on ocean scene ScanSAR images from the Envisat Advanced Synthetic Aperture Radar. The scalloping effect was significantly reduced, with no apparent distortion or smoothing of physical features.

  15. Real-time implementation of frequency-modulated continuous-wave synthetic aperture radar imaging using field programmable gate array

    NASA Astrophysics Data System (ADS)

    Quan, Yinghui; Li, Yachao; Hu, Guibin; Xing, Mengdao

    2015-06-01

    A new miniature linear frequency-modulated continuous-wave radar which mounted on an unmanned aerial vehicle is presented. It allows the accomplishment of high resolution synthetic aperture radar imaging in real-time. Only a Kintex-7 field programmable gate array from Xilinx is utilized for whole signal processing of sophisticated radar imaging algorithms. The proposed hardware architecture achieves remarkable improvement in integration, power consumption, volume, and computing performance over its predecessor designs. The realized design is verified by flight campaigns.

  16. Simulations of Aperture Synthesis Imaging Radar for the EISCAT_3D Project

    NASA Astrophysics Data System (ADS)

    La Hoz, C.; Belyey, V.

    2012-12-01

    EISCAT_3D is a project to build the next generation of incoherent scatter radars endowed with multiple 3-dimensional capabilities that will replace the current EISCAT radars in Northern Scandinavia. Aperture Synthesis Imaging Radar (ASIR) is one of the technologies adopted by the EISCAT_3D project to endow it with imaging capabilities in 3-dimensions that includes sub-beam resolution. Complemented by pulse compression, it will provide 3-dimensional images of certain types of incoherent scatter radar targets resolved to about 100 metres at 100 km range, depending on the signal-to-noise ratio. This ability will open new research opportunities to map small structures associated with non-homogeneous, unstable processes such as aurora, summer and winter polar radar echoes (PMSE and PMWE), Natural Enhanced Ion Acoustic Lines (NEIALs), structures excited by HF ionospheric heating, meteors, space debris, and others. To demonstrate the feasibility of the antenna configurations and the imaging inversion algorithms a simulation of synthetic incoherent scattering data has been performed. The simulation algorithm incorporates the ability to control the background plasma parameters with non-homogeneous, non-stationary components over an extended 3-dimensional space. Control over the positions of a number of separated receiving antennas, their signal-to-noise-ratios and arriving phases allows realistic simulation of a multi-baseline interferometric imaging radar system. The resulting simulated data is fed into various inversion algorithms. This simulation package is a powerful tool to evaluate various antenna configurations and inversion algorithms. Results applied to realistic design alternatives of EISCAT_3D will be described.

  17. Change Detection in Synthetic Aperture Radar Images Based on Deep Neural Networks.

    PubMed

    Gong, Maoguo; Zhao, Jiaojiao; Liu, Jia; Miao, Qiguang; Jiao, Licheng

    2016-01-01

    This paper presents a novel change detection approach for synthetic aperture radar images based on deep learning. The approach accomplishes the detection of the changed and unchanged areas by designing a deep neural network. The main guideline is to produce a change detection map directly from two images with the trained deep neural network. The method can omit the process of generating a difference image (DI) that shows difference degrees between multitemporal synthetic aperture radar images. Thus, it can avoid the effect of the DI on the change detection results. The learning algorithm for deep architectures includes unsupervised feature learning and supervised fine-tuning to complete classification. The unsupervised feature learning aims at learning the representation of the relationships between the two images. In addition, the supervised fine-tuning aims at learning the concepts of the changed and unchanged pixels. Experiments on real data sets and theoretical analysis indicate the advantages, feasibility, and potential of the proposed method. Moreover, based on the results achieved by various traditional algorithms, respectively, deep learning can further improve the detection performance. PMID:26068879

  18. Bistatic synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Yates, Gillian

    Synthetic aperture radar (SAR) allows all-weather, day and night, surface surveillance and has the ability to detect, classify and geolocate objects at long stand-off ranges. Bistatic SAR, where the transmitter and the receiver are on separate platforms, is seen as a potential means of countering the vulnerability of conventional monostatic SAR to electronic countermeasures, particularly directional jamming, and avoiding physical attack of the imaging platform. As the receiving platform can be totally passive, it does not advertise its position by RF emissions. The transmitter is not susceptible to jamming and can, for example, operate at long stand-off ranges to reduce its vulnerability to physical attack. This thesis examines some of the complications involved in producing high-resolution bistatic SAR imagery. The effect of bistatic operation on resolution is examined from a theoretical viewpoint and analytical expressions for resolution are developed. These expressions are verified by simulation work using a simple 'point by point' processor. This work is extended to look at using modern practical processing engines for bistatic geometries. Adaptations of the polar format algorithm and range migration algorithm are considered. The principal achievement of this work is a fully airborne demonstration of bistatic SAR. The route taken in reaching this is given, along with some results. The bistatic SAR imagery is analysed and compared to the monostatic imagery collected at the same time. Demonstrating high-resolution bistatic SAR imagery using two airborne platforms represents what I believe to be a European first and is likely to be the first time that this has been achieved outside the US (the UK has very little insight into US work on this topic). Bistatic target characteristics are examined through the use of simulations. This also compares bistatic imagery with monostatic and gives further insight into the utility of bistatic SAR.

  19. Inverse synthetic aperture radar imaging for concealed object detection on a naturally walking person

    NASA Astrophysics Data System (ADS)

    Zhuravlev, Andrey; Ivashov, Sergey; Razevig, Vladimir; Vasiliev, Igor; Bechtel, Timothy

    2014-05-01

    This paper describes the architecture of a microwave radar system intended for imaging concealed objects under clothing as a subject walks through the inspection area. The system uses the principle of inverse aperture which is achieved by a person's movement past a stationary microwave sensor array. In the system, the vertical resolution is achieved by arranging microwave sensors vertically while the horizontal resolution is due to the subject's horizontal motion. The positioning of the objects is achieved by employing a synchronous video sensor that allows coherent radar signal processing. A possible radar signal processing technique based on signal accumulation is described. Numerical experiments are conducted with the described object trajectory model. The influence of positioning errors attributed to the video positioning system is also modeled numerically. An experimental setup is designed and proposed to evaluate the suggested signal processing techniques on real data with an electro-mechanical scanner and single transceiver. It is suggested that the signal acquisition with the system can be accomplished using the stop motion technique, in which a series of changing stationary scenes is sampled and processed. Experimental radar images are demonstrated for stationary objects with concealed items and considered as reference images. Further development of the system is suggested.

  20. Multi-frequency synthetic-aperture imaging with a lightweight ground penetrating radar system

    NASA Astrophysics Data System (ADS)

    Koppenjan, Steven K.; Allen, Curt M.; Gardner, Duane; Wong, Howard R.; Lee, Hua; Lockwood, Stephanie J.

    2000-03-01

    The detection of buried objects, particularly hazardous waste containers and unexploded ordnance (UXO), has gained significant interest in the Unites States in the late 1990s. The desire to remediate the thousands of sites worldwide has become an increasing concern and the application of radar to this problem has received renewed attention. The US Department of Energy's Special Technologies Laboratory (STL), operated by Bechtel Nevada, has developed several frequency-modulated, continuous-wave (FM-CW) ground penetrating radar (GPR) units. To meet technical requirements for higher-resolution data, STL and the University of California, Santa Barbara (UCSB) is investigating advanced GPR hardware, signal processing, and synthetic-aperture imaging with the development of an innovative system. The goal is to design and fabricate a lightweight, battery-operated unit that does not require surface contact, can be operated by a novice user, and can achieve improved resolution. The latter is accomplished by using synthetic-aperture imaging, which forms the subsurface images by fully utilizing the data sequences collectively along a scan path. We also present the backward propagation algorithm as the basic structure of the multiple-frequency tomographic imaging technique, and the conventional fast Fourier transform (FFT) method which can be described as a degenerated case of the model where the computation procedure is approximated under the narrow-beam assumption.

  1. On the focusing issue of synthetic aperture radar imaging of ocean waves

    SciTech Connect

    Bruning, C. ); Alpers, W.R. ); Schroter, J.G. )

    1991-01-01

    It is now widely accepted that the imaging of ocean surface waves by synthetic aperture radar (SAR) can be adequately described by velocity bunching theory in conjunction with the two-scale wave model. However, it has been conjectured that this theory is incapable of explaining why, under certain conditions, the image contrast of airborne SAR imagery of ocean waves can be enhanced by defocusing the SAR processor. It this were true it would raise serious doubts about the validity of the velocity bunching theory to describe the SAR imaging of ocean waves. In this paper the velocity bunching theory is defended. It is shown that image contrast enhancement by defocusing can also be obtained by this theory, which does not require the introduction of the phase or group velocity of the long ocean waves as a basic element of the SAR imaging theory.

  2. Factors governing selection of operating frequency for subsurface- imaging synthetic-aperture radar

    SciTech Connect

    Brock, B.C.; Patitz, W.E.

    1993-12-31

    A subsurface-imaging synthetic-aperture radar (SISAR) has potential for application in areas as diverse as non-proliferation programs for nuclear weapons to environmental monitoring. However, subsurface imaging is complicated by propagation loss in the soil and surface-clutter response. Both the loss and surface-clutter response depend on the operating frequency. This paper examines several factors which provide a basis for determining optimum frequencies and frequency ranges which will allow synthetic-aperture imaging of buried targets. No distinction can be made between objects at different heights when viewed with a conventional imaging radar (which uses a one-dimensional synthetic aperture), and the return from a buried object must compete with the return from the surface clutter. Thus, the signal-to-clutter ratio is an appropriate measure of performance for a SISAR. A parameter-based modeling approach is used to model the complex dielectric constant of the soil from measured data obtained from the literature. Theoretical random-surface scattering models, based on statistical solutions to Maxwell`s equations, are used to model the clutter. These models are combined to estimate the signal-to-clutter ratio for canonical targets buried in several soil configurations. Results indicate that the HF spectrum (3--30), although it could be used to detect certain targets under some conditions, has limited practical value for use with SISAR, while the upper VIHF through UHF spectrum ({approximately}100 MHz - 1 GHz) shows the most promise for a general purpose SISAR system. Recommendations are included for additional research.

  3. A new look at spotlight mode synthetic aperture radar as tomography: imaging 3-D targets.

    PubMed

    Jakowatz, C V; Thompson, P A

    1995-01-01

    A new 3D tomographic formulation of spotlight mode synthetic aperture radar (SAR) is developed. This extends the pioneering work of Munson et al. (1983), who first formally described SAR in terms of tomography but who made the simplifying assumption that the target scene was 2D. The present authors treat the more general and practical case in which the radar target reflectivities comprise a 3D function. The main goal is to demonstrate that the demodulated radar return data from a spotlight mode collection represent a certain set of samples of the 3D Fourier transform of the target reflectivity function and to do so using a tomographic paradigm instead of traditional range-Doppler analysis. They also show that the tomographic approach is useful in interpreting the reconstructed 2D SAR image corresponding to a 3D scene. Specifically, the well-known SAR phenomenon of layover is easily explained in terms of tomographic projections and is shown to be analogous to the projection effect in conventional optical imaging. PMID:18290021

  4. Ultra-wide-band model-based synthetic aperture radar imaging through complex media

    NASA Astrophysics Data System (ADS)

    Cai, Lixin

    2000-10-01

    It is known that electromagnetic signals can penetrate into non-metallic barriers such as building walls and soil. A portable Synthetic Aperture Radar (SAR) unit capable of transmitting and receiving such signals is desirable in various non-intrusive (proximity or remote) sensing applications. Theoretical and experimental issues associated with Ultra-Wide-Band (UWB) SAR imaging through complex media are studied. The complex media of interest include building walls, underground and foliage. It may be inconvenient and impractical for a hand-held unit to collect data at uniformly spaced positions. A back-projection algorithm is developed for the case where spatial sampling is not uniform. In addition, a spherical wavefront (as opposed to a uniformly planar wavefront) is assumed in the algorithm to account for the proximity of a radar unit relative to a target scene. Imaging results from simulated point target data and measurements of various real targets are obtained. Defocusing and other image defects associated with imaging through complex media using the free space (or dielectric full space) assumption are addressed. Refocusing techniques based on a dielectric wall model and a dielectric half-space model are formulated and imaging results are compared with those generated using the free space assumption.

  5. Registration of multitemporal low-resolution synthetic aperture radar images based on a new similarity measure

    NASA Astrophysics Data System (ADS)

    Ren, Weilong; Song, Jianshe; Zhang, Xiongmei; Cai, Xingfu

    2016-01-01

    Image registration is concerned with the precise overlap of two images. One challenging problem in this area is the registration of low-resolution synthetic aperture radar (SAR) images. In general, extracting feature points from such images is difficult due to the coarse observation and the severe speckle. The use of area similarity for image registration is another important branch to solve the problem. A similarity measure based on a conditional density function (cdf) is proposed. The cdf is specially tailored for SAR images, where the speckle is generally assumed as multiplicative gamma noise with unit mean. Additionally, a two-step procedure is devised for the registration of intro-model SAR images to improve the computational efficiency. First, the two images are roughly aligned considering only the translational difference. Then small blocks from the two images are accurately aligned and the center point of each block is treated as a control point, which is finally used to obtain the precise affine transformation between the two images. Five SAR image datasets are tested in the experiment part, and the results demonstrate the efficiency and accuracy of the proposed method.

  6. Polarimetric analysis of radar backscatter from ground-based scatterometers and wheat biomass monitoring with advanced synthetic aperture radar images

    NASA Astrophysics Data System (ADS)

    He, Lei; Tong, Ling; Li, Yuxia; Chen, Yan; Tan, Longfei; Guo, Caizheng

    2016-04-01

    This article presents an analysis of the scattering measurements for an entire wheat growth cycle by ground-based scatterometers at a frequency of 5.3 GHz. Since wheat ears are related to wheat growth and yield, the radar backscatter of wheat was analyzed at two different periods, i.e., with and without wheat ears. Simultaneously, parameters such as wheat and soil characteristics as well as volume scattering and soil scattering were analyzed for the two periods during the entire growth cycle. Wheat ears have been demonstrated to have a great influence on radar backscatter; therefore, a modified version of water-cloud model used for retrieving biomass should consider the effect of wheat ears. This work presents two retrieval models based on the water-cloud model and adopts the advanced integral equation model to simulate the soil backscatter before the heading stage and the backscatter from the layer under wheat ears after the heading stage. The research results showed that the biomass retrieved from the advanced synthetic aperture radar (ASAR) images to agree well with the data measured in situ after setting the modified water-cloud model for the growth stages with ears. Furthermore, it was concluded that wheat ears should form an essential component of theoretical modeling as they influence the final yield.

  7. SEASAT Synthetic Aperture Radar Data

    NASA Technical Reports Server (NTRS)

    Henderson, F. M.

    1981-01-01

    The potential of radar imagery from space altitudes is discussed and the advantages of radar over passive sensor systems are outlined. Specific reference is made to the SEASAT synthetic aperture radar. Possible applications include oil spill monitoring, snow and ice reconnaissance, mineral exploration, and monitoring phenomena in the urban environment.

  8. Multibeam single frequency synthetic aperture radar processor for imaging separate range swaths

    NASA Technical Reports Server (NTRS)

    Jain, A. (Inventor)

    1979-01-01

    A method and apparatus are described for single frequency multibeam imaging of multiple strips of range swath at high range intervals for those applications where it is desirable to cover a range swath much greater than is possible for a given interpulse interval. Data from a single frequency synthetic aperture radar (in which beam parameters are adjusted so that the return from each successive swath is received during successive interpulse periods) are separated in Dopple frequency for the return from each beam at the frequency plane of the processor. Alternatively, the image formed by each beam may be spatially separated in the azimuth direction and successively selected by positioning an appropriate slit in the recording plane of the processor.

  9. Comparison of synthetic aperture radar and impact-echo imaging for detecting delamination in concrete

    SciTech Connect

    Popovics, J. S.; Ham, S.; Ghasr, M. T.; Zoughi, R.

    2014-02-18

    In this paper we evaluate the utility of microwave and mechanical wave nondestructive testing techniques to detect delamination in reinforced concrete bridge deck mock-up samples. The mechanical wave tests comprise air-coupled impact-echo measurements, while the microwave measurements comprise three-dimensional synthetic aperture radar imaging using wideband reflectometery in the frequency range of 1–4 GHz. The results of these investigations are presented in terms of images that are generated from these data. Based on a comparison of the results, we show that the two methods are complementary, in that provide distinct capabilities for defect detection. More specifically, the former approach is unable to detect depth of a delaminated region, while the latter may provide this information. Therefore, the two methods may be used in a complementary fashion (i.e., data fusion) to give more comprehensive information about the 3D location of delamination.

  10. Study of the Effects of Target Geometry on Synthetic Aperture Radar Images using Simulation Studies

    NASA Astrophysics Data System (ADS)

    Tummala, K.; Jha, A. K.; Kumar, S.

    2014-11-01

    Synthetic aperture radar technology has revolutionized earth observation with very high resolutions of below 5m, making it possible to distinguish individual urban features like buildings and even cars on the surface of the earth. But, the difficulty in interpretation of these images has hindered their use. The geometry of target objects and their orientation with respect to the SAR sensor contribute enormously to unexpected signatures on SAR images. Geometry of objects can cause single, double or multiple reflections which, in turn, affect the brightness value on the SAR images. Occlusions, shadow and layover effects are present in the SAR images as a result of orientation of target objects with respect to the incident microwaves. Simulation of SAR images is the best and easiest way to study and understand the anomalies. This paper discusses synthetic aperture radar image simulation, with the study of effect of target geometry as the main aim. Simulation algorithm has been developed in the time domain to provide greater modularity and to increase the ease of implementation. This algorithm takes into account the sensor and target characteristics, their locations with respect to the earth, 3-dimensional model of the target, sensor velocity, and SAR parameters. two methods have been discussed to obtain position and velocity vectors of SAR sensor - the first, from the metadata of real SAR image used to verify the simulation algorithm, and the second, from satellite orbital parameters. Using these inputs, the SAR image coordinates and backscatter coefficients for each point on the target are calculated. The backscatter coefficients at target points are calculated based on the local incidence angles using Muhleman's backscatter model. The present algorithm has been successfully implemented on radarsat-2 image of San Francisco bay area. Digital elevation models (DEMs) of the area under consideration are used as the 3d models of the target area. DEMs of different

  11. Focusing of synthetic aperture radar ocean images with long integration times

    NASA Astrophysics Data System (ADS)

    Kasilingam, Dayalan P.; Hayt, David W.; Shemdin, Omar H.

    1991-09-01

    Synthetic aperture radar (SAR) images obtained in the SAR and X Band Ocean Nonlinearities: Chesapeake Light Tower (SAXON:CLT) experiment are processed with long integration times (6 s) and analyzed to study the effects of focusing. Two images with near-azimuth-traveling waves were chosen for the study. The first image consists of relatively short wavelength wind waves traveling in the same general direction as the aircraft. The second image consists of a long Atlantic swell traveling in the opposite direction to the aircraft. At these long integration times the image spectral intensities are found to be sensitive to the focus setting. The spectral intensity at the optimum focus is 400% of that at zero focus for the first image and 167% for the second image. The focusing curves for both images agree well with those predicted by a model developed by several groups and referred to here as the "consensus" model. This model predicts an optimum focus setting that is equal to one half of the effective phase speed of the dominant wave in the azimuth direction. The velocity bunching model underpredicts the optimum focus setting significantly. The study concludes that in long-integration-time SAR processing of surface waves, such as the spotlight mode, the image contrast is sensitively dependent on the focus setting and that the optimum focus setting is given by one half of the effective phase speed of the dominant surface wave.

  12. Digital processing considerations for extraction of ocean wave image spectra from raw synthetic aperture radar data

    NASA Technical Reports Server (NTRS)

    Lahaie, I. J.; Dias, A. R.; Darling, G. D.

    1984-01-01

    The digital processing requirements of several algorithms for extracting the spectrum of a detected synthetic aperture radar (SAR) image from the raw SAR data are described and compared. The most efficient algorithms for image spectrum extraction from raw SAR data appear to be those containing an intermediate image formation step. It is shown that a recently developed compact formulation of the image spectrum in terms of the raw data is computationally inefficient when evaluated directly, in comparison with the classical method where matched-filter image formation is an intermediate result. It is also shown that a proposed indirect procedure for digitally implementing the same compact formulation is somewhat more efficient than the classical matched-filtering approach. However, this indirect procedure includes the image formation process as part of the total algorithm. Indeed, the computational savings afforded by the indirect implementation are identical to those obtained in SAR image formation processing when the matched-filtering algorithm is replaced by the well-known 'dechirp-Fourier transform' technique. Furthermore, corrections to account for slant-to-ground range conversion, spherical earth, etc., are often best implemented in the image domain, making intermediate image formation a valuable processing feature.

  13. Universal multifractal scaling of synthetic aperture radar images of sea-ice

    SciTech Connect

    Falco, T.; Francis, F.; Lovejoy, S.; Schertzer, D.; Kerman, B.; Drinkwater, M.

    1996-07-01

    Multifrequency, multipolarization imaging radar scattering coefficient data sets, acquired by synthetic aperture radar (SAR) over sea-ice, were studied in order to reveal their scale-invariant properties. Two distinct scenes were acquired at C-band (5.6 cm) and L-band (25 cm) wavelengths for three different linear polarizations (HH, VV, and HV). These sea-ice radar scattering coefficient fields were investigated by applying both Fourier and multifractal analysis techniques. The (multi) scaling of the data is clearly exhibited in both scenes for all three polarizations at L-band and for the HV polarization at C-band. The fields presenting this symmetry were found to be well described by universal multifractals. The corresponding parameters {alpha}, C{sub 1}, and H were determined for all these fields and were found to vary little with only the parameter H (characterizing the degree of nonconservation) displaying some systematic sensitivity to polarization. The values found for the universal multifractal parameters are {alpha} {approx} 1.85 {+-} 0.05, C{sub 1} {approx} 0.0086 {+-} 0.0041, and H {approx} {minus}0.15 {+-} 0.05.

  14. On the convergence of the phase gradient autofocus algorithm for synthetic aperture radar imaging

    SciTech Connect

    Hicks, M.J.

    1996-01-01

    Synthetic Aperture Radar (SAR) imaging is a class of coherent range and Doppler signal processing techniques applied to remote sensing. The aperture is synthesized by recording and processing coherent signals at known positions along the flight path. Demands for greater image resolution put an extreme burden on requirements for inertial measurement units that are used to maintain accurate pulse-to-pulse position information. The recently developed Phase Gradient Autofocus algorithm relieves this burden by taking a data-driven digital signal processing approach to estimating the range-invariant phase aberrations due to either uncompensated motions of the SAR platform or to atmospheric turbulence. Although the performance of this four-step algorithm has been demonstrated, its convergence has not been modeled mathematically. A new sensitivity study of algorithm performance is a necessary step towards this model. Insights that are significant to the application of this algorithm to both SAR and to other coherent imaging applications are developed. New details on algorithm implementation identify an easily avoided biased phase estimate. A new algorithm for defining support of the point spread function is proposed, which promises to reduce the number of iterations required even for rural scenes with low signal-to-clutter ratios.

  15. Clutter free synthetic aperture radar correlator

    NASA Technical Reports Server (NTRS)

    Jain, A.

    1977-01-01

    A synthetic aperture radar correlation system including a moving diffuser located at the image plane of a radar processor is described. The output of the moving diffuser is supplied to a lens whose impulse response is at least as wide as that of the overall processing system. A significant reduction in clutter results is given.

  16. Real-time implementation of frequency-modulated continuous-wave synthetic aperture radar imaging using field programmable gate array.

    PubMed

    Quan, Yinghui; Li, Yachao; Hu, Guibin; Xing, Mengdao

    2015-06-01

    A new miniature linear frequency-modulated continuous-wave radar which mounted on an unmanned aerial vehicle is presented. It allows the accomplishment of high resolution synthetic aperture radar imaging in real-time. Only a Kintex-7 field programmable gate array from Xilinx is utilized for whole signal processing of sophisticated radar imaging algorithms. The proposed hardware architecture achieves remarkable improvement in integration, power consumption, volume, and computing performance over its predecessor designs. The realized design is verified by flight campaigns. PMID:26133857

  17. Statistical-physical model for foliage clutter in ultra-wideband synthetic aperture radar images

    NASA Astrophysics Data System (ADS)

    Banerjee, Amit; Chellappa, Rama

    2003-01-01

    Analyzing foliage-penetrating (FOPEN) ultra-wideband synthetic aperture radar (SAR) images is a challenging problem owing to the noisy and impulsive nature of foliage clutter. Indeed, many target-detection algorithms for FOPEN SAR data are characterized by high false-alarm rates. In this work, a statistical-physical model for foliage clutter is proposed that explains the presence of outliers in the data and suggests the use of symmetric alpha-stable (SαS) distributions for accurate clutter modeling. Furthermore, with the use of general assumptions of the noise sources and propagation conditions, the proposed model relates the parameters of the SαS model to physical parameters such as the attenuation coefficient and foliage density.

  18. Statistical-physical model for foliage clutter in ultra-wideband synthetic aperture radar images.

    PubMed

    Banerjee, Amit; Chellappa, Rama

    2003-01-01

    Analyzing foliage-penetrating (FOPEN) ultra-wideband synthetic aperture radar (SAR) images is a challenging problem owing to the noisy and impulsive nature of foliage clutter. Indeed, many target-detection algorithms for FOPEN SAR data are characterized by high false-alarm rates. In this work, a statistical-physical model for foliage clutter is proposed that explains the presence of outliers in the data and suggests the use of symmetric alpha-stable (SalphaS) distributions for accurate clutter modeling. Furthermore, with the use of general assumptions of the noise sources and propagation conditions, the proposed model relates the parameters of the SalphaS model to physical parameters such as the attenuation coefficient and foliage density. PMID:12542316

  19. Enhanced Feature Based Mosaicing Technique for Visually and Geometrically Degraded Airborne Synthetic Aperture Radar Images

    NASA Astrophysics Data System (ADS)

    Manikandan, S.; Vardhini, J. P.

    2015-11-01

    In airborne synthetic aperture radar (SAR), there was a major problem encountered in the area of image mosaic in the absence of platform information and sensor information (geocoding), when SAR is applied in large-scale scene and the platform faces large changes. In order to enhance real-time performance and robustness of image mosaic, enhancement based Speeded-Up Robust Features (SURF) mosaic method for airborne SAR is proposed in this paper. SURF is a novel scale-invariant and rotation-invariant feature. It is perfect in its high computation, speed and robustness. In this paper, When the SAR image is acquired, initially the image is enhanced by using local statistic techniques and SURF is applied for SAR image matching accord to its characteristic, and then acquires its invariant feature for matching. In the process of image matching, the nearest neighbor rule for initial matching is used, and the wrong points of the matches are removed through RANSAC fitting algorithm. The proposed algorithm is implemented in different SAR images with difference in scale change, rotation change and noise. The proposed algorithm is compared with other existing algorithms and the quantitative and qualitative measures are calculated and tabulated. The proposed algorithm is robust to changes and the threshold is varied accordingly to increase the matching rate more than 95 %.

  20. A new method for speckle reduction in Synthetic Aperture Radar (SAR) images using optimal window size

    NASA Astrophysics Data System (ADS)

    Mahdavi, S.; Salehi, B.; Moloney, C.; Huang, W.; Brisco, B.

    2016-04-01

    Speckle degrades the radiometric quality of a Synthetic Aperture Radar (SAR) image and makes its visual interpretation difficult. The approaches proposed previously for speckle filtering of SAR images exploit a window of fixed size for this purpose. But a fixed size window is not sufficient as the size of objects may vary throughout the image. In this paper, a method is introduced by which each pixel in the image is filtered using a window size which is optimal for that pixel. Real and imaginary parts of a single-channel SAR image are used for the selection of the best window size for each pixel, and then intensity image is filtered by applying that window size. The Average and Minimum Mean Square Error (MMSE) filters are modified using the Adaptive Window Size method. This approach is implemented on the HH-channel of a RADARSAT-2 image acquired over the Avalon Peninsula near St. John's, Newfoundland, Canada. This filter can supress speckle effectively while retaining the details reasonably.

  1. Multibeam synthetic aperture radar for global oceanography

    NASA Technical Reports Server (NTRS)

    Jain, A.

    1979-01-01

    A single-frequency multibeam synthetic aperture radar concept for large swath imaging desired for global oceanography is evaluated. Each beam iilluminates a separate range and azimuth interval, and images for different beams may be separated on the basis of the Doppler spectrum of the beams or their spatial azimuth separation in the image plane of the radar processor. The azimuth resolution of the radar system is selected so that the Doppler spectrum of each beam does not interfere with the Doppler foldover due to the finite pulse repetition frequency of the radar system.

  2. Detection of flooded urban areas in high resolution Synthetic Aperture Radar images using double scattering

    NASA Astrophysics Data System (ADS)

    Mason, D. C.; Giustarini, L.; Garcia-Pintado, J.; Cloke, H. L.

    2014-05-01

    Flooding is a particular hazard in urban areas worldwide due to the increased risks to life and property in these regions. Synthetic Aperture Radar (SAR) sensors are often used to image flooding because of their all-weather day-night capability, and now possess sufficient resolution to image urban flooding. The flood extents extracted from the images may be used for flood relief management and improved urban flood inundation modelling. A difficulty with using SAR for urban flood detection is that, due to its side-looking nature, substantial areas of urban ground surface may not be visible to the SAR due to radar layover and shadow caused by buildings and taller vegetation. This paper investigates whether urban flooding can be detected in layover regions (where flooding may not normally be apparent) using double scattering between the (possibly flooded) ground surface and the walls of adjacent buildings. The method estimates double scattering strengths using a SAR image in conjunction with a high resolution LiDAR (Light Detection and Ranging) height map of the urban area. A SAR simulator is applied to the LiDAR data to generate maps of layover and shadow, and estimate the positions of double scattering curves in the SAR image. Observations of double scattering strengths were compared to the predictions from an electromagnetic scattering model, for both the case of a single image containing flooding, and a change detection case in which the flooded image was compared to an un-flooded image of the same area acquired with the same radar parameters. The method proved successful in detecting double scattering due to flooding in the single-image case, for which flooded double scattering curves were detected with 100% classification accuracy (albeit using a small sample set) and un-flooded curves with 91% classification accuracy. The same measures of success were achieved using change detection between flooded and un-flooded images. Depending on the particular flooding

  3. Observation of sea-ice dynamics using synthetic aperture radar images: Automated analysis

    NASA Technical Reports Server (NTRS)

    Vesecky, John F.; Samadani, Ramin; Smith, Martha P.; Daida, Jason M.; Bracewell, Ronald N.

    1988-01-01

    The European Space Agency's ERS-1 satellite, as well as others planned to follow, is expected to carry synthetic-aperture radars (SARs) over the polar regions beginning in 1989. A key component in utilization of these SAR data is an automated scheme for extracting the sea-ice velocity field from a time sequence of SAR images of the same geographical region. Two techniques for automated sea-ice tracking, image pyramid area correlation (hierarchical correlation) and feature tracking, are described. Each technique is applied to a pair of Seasat SAR sea-ice images. The results compare well with each other and with manually tracked estimates of the ice velocity. The advantages and disadvantages of these automated methods are pointed out. Using these ice velocity field estimates it is possible to construct one sea-ice image from the other member of the pair. Comparing the reconstructed image with the observed image, errors in the estimated velocity field can be recognized and a useful probable error display created automatically to accompany ice velocity estimates. It is suggested that this error display may be useful in segmenting the sea ice observed into regions that move as rigid plates of significant ice velocity shear and distortion.

  4. The Effect of Synthetic Aperture Radar Image Resolution on Target Discrimination

    NASA Astrophysics Data System (ADS)

    Terzuoli, Andrew; McGowan, John; Gustafson, Steven; Jackson, Julie; Martin, Richard

    This research details the effect of spatial resolution on target discrimination in Synthetic Aper-ture Radar (SAR) images. Multiple SAR image chips containing targets and non-targets are used to test a baseline Automatic Target Recognition (ATR) system with reduced spatial reso-lution obtained by lowering the pixel count or synthesizing a degraded image. The pixel count is lowered by averaging groups of adjoining pixels to form a new single value. The degraded image is synthesized by low-pass filtering the image frequency space and then lowering the pixel count. A two parameter Constant False Alarm Rate (CFAR) detector is tested, and three different types of feature spaces; size, contrast, and texture; are used to train a linear classifier. The results are scored using the Area Under the Receiver Operator Characteristic (AUROC) curve. The CFAR detector is shown to perform better at lower resolution. All three feature sets together performed well with the degradation of resolution; separately the sets had different performances. The texture features performed best because they do not rely on the number of pixels on the target, while the size features performed worst for the same reason. The contrast features yielded improved performance when the resolution was slightly reduced. The views expressed in this article are those of the authors and do not reflect the official policy of the U.S. Air Force, U.S. Department of Defense, or the U.S. Government.

  5. The effect of synthetic aperture radar image resolution on target discrimination

    NASA Astrophysics Data System (ADS)

    McGowan, John E.; Gustafson, Steven C.; Jackson, Julie A.; Terzuoli, Andrew J., Jr.

    2010-04-01

    This paper details the effect of spatial resolution on target discrimination in Synthetic Aperture Radar (SAR) images. Multiple SAR image chips, containing targets and non-targets, are used to test a baseline Automatic Target Recognition (ATR) system with reduced spatial resolution obtained by lowering the pixel count or synthesizing a degraded image. The pixel count is lowered by averaging groups of adjoining pixels to form a new single value. The degraded image is synthesized by low-pass-filtering the image frequency space and then lowering the pixel count. To train a linear classifier, a two-parameter Constant False Alarm Rate (CFAR) detector is tested, and three different types of feature spaces, are used: size, contrast, and texture. The results are scored using the Area Under the Receiver Operator Characteristic (AUROC) curve. The CFAR detector is shown to perform better at lower resolution. All three feature sets together performed well with the degradation of resolution; separately the sets had different performances. The texture features performed best because they do not rely on the number of pixels on the target, while the size features performed the worst for the same reason. The contrast features yielded improved performance when the resolution was slightly reduced.

  6. Miniature synthetic-aperture radar system

    NASA Astrophysics Data System (ADS)

    Stockton, Wayne; Stromfors, Richard D.

    1990-11-01

    Loral Defense Systems-Arizona has developed a high-performance synthetic-aperture radar (SAR) for small aircraft and unmanned aerial vehicle (UAV) reconnaissance applications. This miniature radar, called Miniature Synthetic-Aperture Radar (MSAR), is packaged in a small volume and has low weight. It retains key features of large SAR systems, including high-resolution imaging and all-weather operation. The operating frequency of MSAR can optionally be selected to provide foliage penetration capability. Many imaging radar configurations can be derived using this baseline system. MSAR with a data link provides an attractive UAV sensor. MSAR with a real-time image formation processor is well suited to installations where onboard processing and immediate image analysis are required. The MSAR system provides high-resolution imaging for short-to-medium range reconnaissance applications.

  7. Automatic position calculating imaging radar with low-cost synthetic aperture sensor for imaging layered media

    DOEpatents

    Mast, J.E.

    1998-08-18

    An imaging system for analyzing structures comprises a radar transmitter and receiver connected to a timing mechanism that allows a radar echo sample to be taken at a variety of delay times for each radar pulse transmission. The radar transmitter and receiver are coupled to a position determining system that provides the x,y position on a surface for each group of samples measured for a volume from the surface. The radar transmitter and receiver are moved about the surface to collect such groups of measurements from a variety of x,y positions. Return signal amplitudes represent the relative reflectivity of objects within the volume and the delay in receiving each signal echo represents the depth at which the object lays in the volume and the propagation speeds of the intervening material layers. Successively deeper z-planes are backward propagated from one layer to the next with an adjustment for variations in the expected propagation velocities of the material layers that lie between adjacent z-planes. 10 figs.

  8. Automatic position calculating imaging radar with low-cost synthetic aperture sensor for imaging layered media

    DOEpatents

    Mast, Jeffrey E.

    1998-01-01

    An imaging system for analyzing structures comprises a radar transmitter and receiver connected to a timing mechanism that allows a radar echo sample to be taken at a variety of delay times for each radar pulse transmission. The radar transmitter and receiver are coupled to a position determining system that provides the x,y position on a surface for each group of samples measured for a volume from the surface. The radar transmitter and receiver are moved about the surface to collect such groups of measurements from a variety of x,y positions. Return signal amplitudes represent the relative reflectivity of objects within the volume and the delay in receiving each signal echo represents the depth at which the object lays in the volume and the propagation speeds of the intervening material layers. Successively deeper z-planes are backward propagated from one layer to the next with an adjustment for variations in the expected propagation velocities of the material layers that lie between adjacent z-planes.

  9. Optimal waveform-based clutter suppression algorithm for recursive synthetic aperture radar imaging systems

    NASA Astrophysics Data System (ADS)

    Zhu, Binqi; Gao, Yesheng; Wang, Kaizhi; Liu, Xingzhao

    2016-04-01

    A computational method for suppressing clutter and generating clear microwave images of targets is proposed in this paper, which combines synthetic aperture radar (SAR) principles with recursive method and waveform design theory, and it is suitable for SAR for special applications. The nonlinear recursive model is introduced into the SAR operation principle, and the cubature Kalman filter algorithm is used to estimate target and clutter responses in each azimuth position based on their previous states, which are both assumed to be Gaussian distributions. NP criteria-based optimal waveforms are designed repeatedly as the sensor flies along its azimuth path and are used as the transmitting signals. A clutter suppression filter is then designed and added to suppress the clutter response while maintaining most of the target response. Thus, with fewer disturbances from the clutter response, we can generate the SAR image with traditional azimuth matched filters. Our simulations show that the clutter suppression filter significantly reduces the clutter response, and our algorithm greatly improves the SINR of the SAR image based on different clutter suppression filter parameters. As such, this algorithm may be preferable for special target imaging when prior information on the target is available.

  10. Improved superpixel-based polarimetric synthetic aperture radar image classification integrating color features

    NASA Astrophysics Data System (ADS)

    Xing, Yanxiao; Zhang, Yi; Li, Ning; Wang, Robert; Hu, Guixiang

    2016-04-01

    Various polarimetric features including scattering matrix, covariance matrix, polarimetric decomposition results, and textural or spatial information have already been used for polarimetric synthetic aperture radar (PolSAR) image classification. However, color features are rarely involved. We propose an improved superpixel-based PolSAR image classification integrating color features. First, we extract the color information using polarimetric decomposition. Second, by combining the color and spatial information of pixels, modified simple linear iterative clustering is used to generate small regions called superpixels. Then we apply Wishart distance to the superpixels to classify them into different classes. This method is demonstrated using the L-band Flevoland PolSAR data from AirSAR and Oberpfaffenhofen PolSAR data from ESAR. The results show that this method works well for areas with homogeneous terrains like farms in terms of both classification accuracy and computational efficiency. Furthermore, the success of the proposed method signifies that more color features can be discovered in the future research works.

  11. Detection of Built-Up Areas Using Polarimetric Synthetic Aperture Radar Data and Hyperspectral Image

    NASA Astrophysics Data System (ADS)

    Bordbari, R.; Maghsoudi, Y.; Salehi, M.

    2015-12-01

    Polarimetric synthetic aperture radar (POLSAR) is an advantageous data for information extraction about objects and structures by using the wave scattering and polarization properties. Hyperspectral remote sensing exploits the fact that all materials reflect, absorb, and emit electromagnetic energy, at specific wavelengths, in distinctive patterns related to their molecular composition. As a result of their fine spectral resolution, Hyperspectral image (HIS) sensors provide a significant amount of information about the physical and chemical composition of the materials occupying the pixel surface. In target detection applications, the main objective is to search the pixels of an HSI data cube for the presence of a specific material (target). In this research, a hierarchical constrained energy minimization (hCEM) method using 5 different adjusting parameters has been used for target detection from hyperspectral data. Furthermore, to detect the built-up areas from POLSAR data, building objects discriminated from surrounding natural media presented on the scene using Freeman polarimetric target decomposition (PTD) and the correlation coefficient between co-pol and cross-pol channels. Also, target detection method has been implemented based on the different polarization basis for using the more information. Finally a majority voting method has been used for fusing the target maps. The polarimetric image C-band SAR data acquired by Radarsat-2, over San Francisco Bay area was used for the evaluation of the proposed method.

  12. Polarimetric synthetic aperture radar image classification using fuzzy logic in the H/α-Wishart algorithm

    NASA Astrophysics Data System (ADS)

    Zhu, Teng; Yu, Jie; Li, Xiaojuan; Yang, Jie

    2015-01-01

    To solve the problem that the H/α-Wishart unsupervised classification algorithm can generate only inflexible clusters due to arbitrarily fixed zone boundaries in the clustering processing, a refined fuzzy logic based classification scheme called the H/α-Wishart fuzzy clustering algorithm is proposed in this paper. A fuzzy membership function was developed for the degree of pixels belonging to each class instead of an arbitrary boundary. To devise a unified fuzzy function, a normalized Wishart distance is proposed during the clustering step in the new algorithm. Then the degree of membership is computed to implement fuzzy clustering. After an iterative procedure, the algorithm yields a classification result. The new classification scheme is applied to two L-band polarimetric synthetic aperture radar (PolSAR) images and an X-band high-resolution PolSAR image of a field in LingShui, Hainan Province, China. Experimental results show that the classification precision of the refined algorithm is greater than that of the H/α-Wishart algorithm and that the refined algorithm performs well in differentiating shadows and water areas.

  13. Advanced Interferometric Synthetic Aperture Imaging Radar (InSAR) for Dune Mapping

    NASA Astrophysics Data System (ADS)

    Havivi, Shiran; Amir, Doron; Schvartzman, Ilan; August, Yitzhak; Mamman, Shimrit; Rotman, Stanely R.; Blumberg, Dan G.

    2016-04-01

    Aeolian morphologies are formed in the presence of sufficient wind energy and available lose particles. These processes occur naturally or are further enhanced or reduced by human intervention. The dimensions of change are dependent primarily on the wind energy and surface properties. Since the 1970s, remote sensing imagery, both optical and radar, have been used for documentation and interpretation of the geomorphologic changes of sand dunes. Remote sensing studies of aeolian morphologies is mostly useful to document major changes, yet, subtle changes, occurring in a period of days or months in scales of centimeters, are very difficult to detect in imagery. Interferometric Synthetic Aperture Radar (InSAR) is an imaging technique for measuring Earth's surface topography and deformation. InSAR images are produced by measuring the radar phase difference between two separated antennas that view the same surface area. Classical InSAR is based on high coherence between two or more images. The output (interferogram) can show subtle changes with an accuracy of several millimeters to centimeters. Very little work has been done on measuring or identifying the changes in dunes using InSAR methods. The reason is that dunes tend to be less coherent than firm, stable, surfaces. This work aims to demonstrate how interferometric decorrelation can be used for identifying dune instability. We hypothesize and demonstrate that the loss of radar coherence over time on dunes can be used as an indication of the dune's instability. When SAR images are acquired at sufficiently close intervals one can measure the time it takes to lose coherence and associate this time with geomorphic stability. To achieve our goals, the coherence change detection method was used, in order to identify dune stability or instability and the dune activity level. The Nitzanim-Ashdod coastal dunes along the Mediterranean, 40 km south of Tel-Aviv, Israel, were chosen as a case study. The dunes in this area are of

  14. Detection of flooded urban areas in high resolution Synthetic Aperture Radar images using double scattering

    NASA Astrophysics Data System (ADS)

    Mason, David; Giustarini, Laura; Garcia-Pintado, Javier; Cloke, Hannah

    2014-05-01

    compared to an un-flooded image of the same area acquired with the same radar parameters. The method proved successful in detecting double scattering due to flooding in the single-image case, for which flooded double scattering curves were detected with 100% classification accuracy (albeit using a small sample set) and un-flooded curves with 91% classification accuracy. The same measures of success were achieved using change detection between flooded and un-flooded images. Depending on the particular flooding situation, the method could lead to improved detection of flooding in urban areas. 1. Mason DC, Giustarini L, Garcia-Pintado J (2014). Detection of flooded urban areas in high resolution Synthetic Aperture Radar images using double scattering. Int. J. Applied Earth Observation and Geoscience, 28C (May 2014), 150-159.

  15. Detection of small, slow ground targets using Synthetic Aperture Radar

    NASA Technical Reports Server (NTRS)

    Chen, Curtis; Chapin, Elaine; Rosen, Paul

    2005-01-01

    Synthetic aperture radar (SAR) along-track interferometry (ATI) is a technique for sensing Earth-surface motion. The technique involves interferometrically combining data from two radar images acquired from phase centers separated along the platform flight track.

  16. Brief Communication: Contrast-stretching- and histogram-smoothness-based synthetic aperture radar image enhancement for flood map generation

    NASA Astrophysics Data System (ADS)

    Nazir, F.; Riaz, M. M.; Ghafoor, A.; Arif, F.

    2015-02-01

    Synthetic-aperture-radar-image-based flood map generation is usually a challenging task (due to degraded contrast). A three-step approach (based on adaptive histogram clipping, histogram remapping and smoothing) is proposed for generation of a more visualized flood map image. The pre- and post-flood images are adaptively histogram equalized. The hidden details in difference image are enhanced using contrast-based enhancement and histogram smoothing. A fast-ready flood map is then generated using equalized pre-, post- and difference images. Results (evaluated using different data sets) show significance of the proposed technique.

  17. Transient volcano deformation sources imaged with interferometric synthetic aperture radar: Application to Seguam Island, Alaska

    USGS Publications Warehouse

    Masterlark, Timothy; Lu, Zhong

    2004-01-01

    Thirty interferometric synthetic aperture radar (InSAR) images, spanning various intervals during 1992–2000, document coeruptive and posteruptive deformation of the 1992–1993 eruption on Seguam Island, Alaska. A procedure that combines standard damped least squares inverse methods and collective surfaces, identifies three dominant amorphous clusters of deformation point sources. Predictions generated from these three point source clusters account for both the spatial and temporal complexity of the deformation patterns of the InSAR data. Regularized time series of source strength attribute a distinctive transient behavior to each of the three source clusters. A model that combines magma influx, thermoelastic relaxation, poroelastic effects, and petrologic data accounts for the transient, interrelated behavior of the source clusters and the observed deformation. Basaltic magma pulses, which flow into a storage chamber residing in the lower crust, drive this deformational system. A portion of a magma pulse is injected into the upper crust and remains in storage during both coeruption and posteruption intervals. This injected magma degasses and the volatile products accumulate in a shallow poroelastic storage chamber. During the eruption, another portion of the magma pulse is transported directly to the surface via a conduit roughly centered beneath Pyre Peak on the west side of the island. A small amount of this magma remains in storage during the eruption, and posteruption thermoelastic contraction ensues. This model, made possible by the excellent spatial and temporal coverage of the InSAR data, reveals a relatively simple system of interrelated predictable processes driven by magma dynamics.

  18. Wide area, coarse resolution imaging with satellite-borne synthetic aperture radars in low-earth and geosynchronous orbits

    NASA Technical Reports Server (NTRS)

    Tomiyasu, K.

    1981-01-01

    The LEOSAR (low-earth-orbit synthetic aperture radar) can map around the earth, while the GEOSAR (geosynchronous synthetic aperture radar) can map a large global area bounded in both longitudinal and latitudinal ranges. This paper presents the mapping capabilities and power requirements of both LEOSAR and GEOSAR. For a low-earth-orbit SAR, images of swath widths of the order of 700 km are possible with 100-m resolution and 300 watts of average transmitter power at 9375 MHz. From a SAR in a 50-deg inclined geosynchronous circular orbit, the contiguous United States can be imaged in about 6.4 hours with 100-m resolution, 345 watts of average transmitter power, and a data rate of 6 megabits/sec at 2450 MHz.

  19. Future of synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Barath, F. T.

    1978-01-01

    The present status of the applications of Synthetic Aperture Radars (SARs) is reviewed, and the technology state-of-the art as represented by the Seasat-A and SIR-A SARs examined. The potential of SAR applications, and the near- and longer-term technology trends are assessed.

  20. Differential Optical Synthetic Aperture Radar

    DOEpatents

    Stappaerts, Eddy A.

    2005-04-12

    A new differential technique for forming optical images using a synthetic aperture is introduced. This differential technique utilizes a single aperture to obtain unique (N) phases that can be processed to produce a synthetic aperture image at points along a trajectory. This is accomplished by dividing the aperture into two equal "subapertures", each having a width that is less than the actual aperture, along the direction of flight. As the platform flies along a given trajectory, a source illuminates objects and the two subapertures are configured to collect return signals. The techniques of the invention is designed to cancel common-mode errors, trajectory deviations from a straight line, and laser phase noise to provide the set of resultant (N) phases that can produce an image having a spatial resolution corresponding to a synthetic aperture.

  1. Science Results from the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR): Progress Report

    NASA Technical Reports Server (NTRS)

    Evans, Diane L. (Editor); Plaut, Jeffrey (Editor)

    1996-01-01

    The Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) is the most advanced imaging radar system to fly in Earth orbit. Carried in the cargo bay of the Space Shuttle Endeavour in April and October of 1994, SIR-C/X-SAR simultaneously recorded SAR data at three wavelengths (L-, C-, and X-bands; 23.5, 5.8, and 3.1 cm, respectively). The SIR-C/X-SAR Science Team consists of 53 investigator teams from more than a dozen countries. Science investigations were undertaken in the fields of ecology, hydrology, ecology, and oceanography. This report contains 44 investigator team reports and several additional reports from coinvestigators and other researchers.

  2. SIR-B synthetic aperture radar image of California taken during 41-G mission

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Image of Mt. Shasta volcano (conical peak at left) in northern California was acquired by the Shuttle Imaging Radar-B (SIR-B) during the STS 41-G mission aboard the shuttle Challenger. Mt. Shasta is surrounded by bright-appearing lava flows, the Shasta valley (left) and Squaw Valley (right).

  3. Interferometric inverse synthetic aperture radar imaging for space targets based on wideband direct sampling using two antennas

    NASA Astrophysics Data System (ADS)

    Tian, Biao; Liu, Yang; Xu, Shiyou; Chen, Zengping

    2014-01-01

    Interferometric inverse synthetic aperture radar (InISAR) imaging provides complementary information to monostatic inverse synthetic aperture radar (ISAR) imaging. This paper proposes a new InISAR imaging system for space targets based on wideband direct sampling using two antennas. The system is easy to realize in engineering since the motion trajectory of space targets can be known in advance, which is simpler than that of three receivers. In the preprocessing step, high speed movement compensation is carried out by designing an adaptive matched filter containing speed that is obtained from the narrow band information. Then, the coherent processing and keystone transform for ISAR imaging are adopted to reserve the phase history of each antenna. Through appropriate collocation of the system, image registration and phase unwrapping can be avoided. Considering the situation not to be satisfied, the influence of baseline variance is analyzed and compensation method is adopted. The corresponding size can be achieved by interferometric processing of the two complex ISAR images. Experimental results prove the validity of the analysis and the three-dimensional imaging algorithm.

  4. Mapping of sea ice and measurement of its drift using aircraft synthetic aperture radar images

    NASA Technical Reports Server (NTRS)

    Leberl, F.; Bryan, M. L.; Elachi, C.; Farr, T.; Campbell, W.

    1979-01-01

    Side-looking radar images of Arctic sea ice were obtained as part of the Arctic Ice Dynamics Joint Experiment. Repetitive coverages of a test site in the Arctic were used to measure sea ice drift, employing single images and blocks of overlapping radar image strips; the images were used in conjunction with data from the aircraft inertial navigation and altimeter. Also, independently measured, accurate positions of a number of ground control points were available. Initial tests of the method were carried out with repeated coverages of a land area on the Alaska coast (Prudhoe). Absolute accuracies achieved were essentially limited by the accuracy of the inertial navigation data. Errors of drift measurements were found to be about + or - 2.5 km. Relative accuracy is higher; its limits are set by the radar image geometry and the definition of identical features in sequential images. The drift of adjacent ice features with respect to one another could be determined with errors of less than + or - 0.2 km.

  5. Automatic target classification of man-made objects in synthetic aperture radar images using Gabor wavelet and neural network

    NASA Astrophysics Data System (ADS)

    Vasuki, Perumal; Roomi, S. Mohamed Mansoor

    2013-01-01

    Processing of synthetic aperture radar (SAR) images has led to the development of automatic target classification approaches. These approaches help to classify individual and mass military ground vehicles. This work aims to develop an automatic target classification technique to classify military targets like truck/tank/armored car/cannon/bulldozer. The proposed method consists of three stages via preprocessing, feature extraction, and neural network (NN). The first stage removes speckle noise in a SAR image by the identified frost filter and enhances the image by histogram equalization. The second stage uses a Gabor wavelet to extract the image features. The third stage classifies the target by an NN classifier using image features. The proposed work performs better than its counterparts, like K-nearest neighbor (KNN). The proposed work performs better on databases like moving and stationary target acquisition and recognition against the earlier methods by KNN.

  6. A comparison of spatial sampling techniques enabling first principles modeling of a synthetic aperture RADAR imaging platform

    NASA Astrophysics Data System (ADS)

    Gartley, Michael; Goodenough, Adam; Brown, Scott; Kauffman, Russel P.

    2010-04-01

    Simulation of synthetic aperture radar (SAR) imagery may be approached in many different ways. One method treats a scene as a radar cross section (RCS) map and simply evaluates the radar equation, convolved with a system impulse response to generate simulated SAR imagery. Another approach treats a scene as a series of primitive geometric shapes, for which a closed form solution for the RCS exists (such as boxes, spheres and cylinders), and sums their contribution at the antenna level by again solving the radar equation. We present a ray-tracing approach to SAR image simulation that treats a scene as a series of arbitrarily shaped facetized objects, each facet potentially having a unique radio frequency optical property and time-varying location and orientation. A particle based approach, as compared to a wave based approach, presents a challenge for maintaining coherency of sampled scene points between pulses that allows the reconstruction of an exploitable image from the modeled complex phase history. We present a series of spatial sampling techniques and their relative success at producing accurate phase history data for simulations of spotlight, stripmap and SAR-GMTI collection scenarios.

  7. Estimating vegetation biomass using synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Baronti, Stefano; Luciani, S.; Paloscia, Simonetta; Schiavon, G.; Sigismondi, S.; Solimini, Domenico

    1994-12-01

    A significant experiment for evaluating the potential of Synthetic Aperture Radar (SAR) in monitoring soil and vegetation parameters is being carried out on an agricultural area located in Central Italy. The site has been imaged in 1991 by NASA/JPL AIRSAR during the MAC-91 Campaign and subsequently by ESA/ERS-1 and NASDA JERS-1 in 1992. The sensitivity to vegetation biomass of backscattering coefficient measured by ERS-1 and JERS-1 radars is discussed and compared with the best results achieved using the multifrequency polarimetric AIRSAR data.

  8. Addressing Three Fallacies About Synthetic Aperture Radar

    NASA Astrophysics Data System (ADS)

    Atwood, Don; Garron, Jessica

    2013-12-01

    Synthetic aperture radar (SAR) has long been recognized as a valuable tool for real-time environmental analysis and understanding of the Earth's geophysical properties. With its ability to see through clouds and to image day and night in all seasons, it can provide high-resolution data when optical sensors cannot. This capability has enabled SAR scientists to delineate flooding events, assess earthquake damage, map forest fires, rescue trapped icebreakers, and identify the extent of oil spills.

  9. Method for providing a polarization filter for processing synthetic aperture radar image data

    NASA Technical Reports Server (NTRS)

    Dubois, Pascale C. (Inventor); vanZyl, Jakob J. (Inventor)

    1991-01-01

    A polarization filter can maximize the signal-to-noise ratio of a polarimetric SAR and help discriminate between targets or enhance image features, e.g., enhance contract between different types of target. The method disclosed is based on the Stokes matrix/Stokes vector representation, so the targets of interest can be extended targets, and the method can also be applied to the case of bistatic polarimetric radars.

  10. Soviet oceanographic synthetic aperture radar (SAR) research

    SciTech Connect

    Held, D.N.; Gasparovic, R.F.; Mansfield, A.W.; Melville, W.K.; Mollo-Christensen, E.L.; Zebker, H.A.

    1991-01-01

    Radar non-acoustic anti-submarine warfare (NAASW) became the subject of considerable scientific investigation and controversy in the West subsequent to the discovery by the Seasat satellite in 1978 that manifestations of underwater topography, thought to be hidden from the radar, were visible in synthetic aperture radar (SAR) images of the ocean. In addition, the Seasat radar produced images of ship wakes where the observed angle between the wake arms was much smaller than expected from classical Kelvin wake theory. These observations cast doubt on the radar oceanography community's ability to adequately explain these phenomena, and by extension on the ability of existing hydrodynamic and radar scattering models to accurately predict the observability of submarine-induced signatures. If one is of the opinion that radar NAASW is indeed a potentially significant tool in detecting submerged operational submarines, then the Soviet capability, as evidenced throughout this report, will be somewhat daunting. It will be shown that the Soviets have extremely fine capabilities in both theoretical and experimental hydrodynamics, that Soviet researchers have been conducting at-sea radar remote sensing experiments on a scale comparable to those of the United States for several years longer than we have, and that they have both an airborne and spaceborne SAR capability. The only discipline that the Soviet Union appears to be lacking is in the area of digital radar signal processing. If one is of the opinion that radar NAASW can have at most a minimal impact on the detection of submerged submarines, then the Soviet effort is of little consequence and poses not threat. 280 refs., 31 figs., 12 tabs.

  11. Three-dimensional subsurface imaging synthetic aperture radar (3D SISAR). Final report, September 22, 1993--September 22, 1996

    SciTech Connect

    1998-12-31

    The concept developed under this applied research and development contract is a novel Ground Penetrating Radar system capable of remotely detecting, analyzing, and mapping buried waste containers from a mobile platform. From the testing and analysis performed to date, the 3-D SISAR has achieved the detection, accurate location, and three-dimensional imaging of buried test objects from a stand-off geometry. Tests have demonstrated that underground objects have been located to within 0.1 meter of their actual position. This work validates that the key elements of the approach are performing as anticipated. The stand-off synthetic aperture radar (SAR) methodology has been demonstrated to be a feasible approach as a remote sensing technique. The radar sensor constructed under this project is providing adequate quality data for imaging, and the matched filters have been demonstrated to provide enhanced target detection. Additional work is on-going in the area of underground propagation and scattering phenomena to provide enhanced depth performance, as the current imaging results have been limited to a few feet of depth underground.

  12. Imaging method for downward-looking sparse linear array three-dimensional synthetic aperture radar based on reweighted atomic norm

    NASA Astrophysics Data System (ADS)

    Bao, Qian; Han, Kuoye; Lin, Yun; Zhang, Bingchen; Liu, Jianguo; Hong, Wen

    2016-01-01

    We propose an imaging algorithm for downward-looking sparse linear array three-dimensional synthetic aperture radar (DLSLA 3-D SAR) in the circumstance of cross-track sparse and nonuniform array configuration. Considering the off-grid effect and the resolution improvement, the algorithm combines pseudo-polar formatting algorithm, reweighed atomic norm minimization (RANM), and a parametric relaxation-based cyclic approach (RELAX) to improve the imaging performance with a reduced number of array antennas. RANM is employed in the cross-track imaging after pseudo-polar formatting the DLSLA 3-D SAR echo signal, then the reconstructed results are refined by RELAX. By taking advantage of the reweighted scheme, RANM can improve the resolution of the atomic norm minimization, and outperforms discretized compressive sensing schemes that suffer from off-grid effect. The simulated and real data experiments of DLSLA 3-D SAR verify the performance of the proposed algorithm.

  13. Synthetic aperture radar processing with tiered subapertures

    SciTech Connect

    Doerry, A.W.

    1994-06-01

    Synthetic Aperture Radar (SAR) is used to form images that are maps of radar reflectivity of some scene of interest, from range soundings taken over some spatial aperture. Additionally, the range soundings are typically synthesized from a sampled frequency aperture. Efficient processing of the collected data necessitates using efficient digital signal processing techniques such as vector multiplies and fast implementations of the Discrete Fourier Transform. Inherent in image formation algorithms that use these is a trade-off between the size of the scene that can be acceptably imaged, and the resolution with which the image can be made. These limits arise from migration errors and spatially variant phase errors, and different algorithms mitigate these to varying degrees. Two fairly successful algorithms for airborne SARs are Polar Format processing, and Overlapped Subaperture (OSA) processing. This report introduces and summarizes the analysis of generalized Tiered Subaperture (TSA) techniques that are a superset of both Polar Format processing and OSA processing. It is shown how tiers of subapertures in both azimuth and range can effectively mitigate both migration errors and spatially variant phase errors to allow virtually arbitrary scene sizes, even in a dynamic motion environment.

  14. Two-beam coupling correlation synthetic aperture radar image recognition with power-law scattering centers pre-enhancement

    NASA Astrophysics Data System (ADS)

    Haji-saeed, Bahareh; Khoury, Jed; Woods, Charles L.; Kierstead, John

    2008-03-01

    Synthetic radar image recognition is an area of interest for military applications including automatic target recognition, air traffic control, and remote sensing. Here a dynamic range compression two-beam coupling joint transform correlator for detecting synthetic aperture radar (SAR) targets is utilized. The joint input image consists of a pre-power-law, enhanced scattering center of the input image and a linearly synthesized power-law enhanced scattering center template. Enhancing the scattering center of both the synthetic template and the input image furnishes the conditions for achieving dynamic range compression correlation in two-beam coupling. Dynamic range compression: (a) enhances the signal to noise ratio, (b) enhances the high frequencies relative to low frequencies, and (c) converts the noise to high frequency components. This improves the correlation peak intensity to the mean of the surrounding noise significantly. Dynamic range compression correlation has already been demonstrated to outperform many optimal correlation filters in detecting signals in severe noise environments. The performance is evaluated via established metrics, such as peak-to-correlation energy (PCE), Horner efficiency and correlation peak intensity. The results showed significant improvement as the power increased.

  15. Inverse synthetic aperture radar: Preliminary results

    NASA Astrophysics Data System (ADS)

    Eerland, K. K.

    1982-06-01

    Theory and results of simulations, associated with inverse synthetic aperture radar (ISAR) imaging are discussed. A radar signal processing algorithm was developed which derives an ISAR image of an aircraft model. This algorithm assumes a straight unaccelerated flight path and an accurate measurement of the flight path parameters in order to perform proper imaging. However, in practice an aircraft may be maneuvering during the observation and also some flight path parameters may be measured in-accurately. In order to compensate for the two most frequent disturbing effects, the algorithm makes use of two specific correction methods. First, a measurement error in the target velocity is removed by means of an optimization procedure and, secondly, a compensation for a curved flight path is performed. Attention is also given to the influence of observation noise. The noise is assumed to be stationary, Gaussian and white (a uniform spectrum).

  16. Performance Analysis of a Digital Image Synthesizer as a Counter-Measure Against Inverse Synthetic Aperture Radar

    NASA Astrophysics Data System (ADS)

    LeDantec, Fernando A.

    2002-09-01

    This thesis is concerned with the development of a model to analyze a Digital Image Synthesizer (DIS) integrated circuit designed to create false target images to deceive Inverse Synthetic Aperture Radar (ISAR). The DIS is able to recreate the scattering effect of a moving target by using appropriate phase and gain modulations on an intercepted ISAR chirp signal before retransmitting it with the proper time delay. The DIS signal processing and the ISAR compression of the modulated return are modeled to examine the range-Doppler profile of a synthesized false target image. The image is representative of the image that would appear on an ISAR display. ISAR image quality is used to evaluate different DIS architectures and bit formats. Evaluation of the image quality is based on the deviation from an infinite resolution false target image. The results obtained from evaluating different DIS architectures indicate that the design is tolerant of significant quantization errors. The model is used to validate the architecture of the integrated circuit being fabricated. Finally, various different ISAR integration times and pulse repetition frequencies are used to confirm the integrity of the model.

  17. Cancellation of singularities for synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Caday, Peter

    2015-01-01

    In a basic model for synthetic aperture radar (SAR) imaging, one wishes to recover a function or distribution f from line integrals over circles whose centers lie on a given curve γ. In this paper, we consider the problem of recovering the singularities (wavefront set) of f given its SAR data, and specifically whether it is possible to choose a singular f whose singularities are hidden from γ, meaning that its SAR data is smooth. We show that f 's singularities can be hidden to leading order if a certain discrete reflection map is the identity, and give examples where this is the case. Finally, numerical experiments illustrate the hiding of singularities.

  18. Analysis of polarimetric synthetic aperture radar and passive visible light polarimetric imaging data fusion for remote sensing applications

    NASA Astrophysics Data System (ADS)

    Maitra, Sanjit

    The recent launch of spaceborne (TerraSAR-X, RADARSAT-2, ALOS-PALSAR, RISAT) and airborne (SIRC, AIRSAR, UAVSAR, PISAR) polarimetric radar sensors, with capability of imaging through day and night in almost all weather conditions, has made polarimetric synthetic aperture radar (PolSAR) image interpretation and analysis an active area of research. PolSAR image classification is sensitive to object orientation and scattering properties. In recent years, significant work has been done in many areas including agriculture, forestry, oceanography, geology, terrain analysis. Visible light passive polarimetric imaging has also emerged as a powerful tool in remote sensing for enhanced information extraction. The intensity image provides information on materials in the scene while polarization measurements capture surface features, roughness, and shading, often uncorrelated with the intensity image. Advantages of visible light polarimetric imaging include high dynamic range of polarimetric signatures and being comparatively straightforward to build and calibrate. This research is about characterization and analysis of the basic scattering mechanisms for information fusion between PolSAR and passive visible light polarimetric imaging. Relationships between these two modes of imaging are established using laboratory measurements and image simulations using the Digital Image and Remote Sensing Image Generation (DIRSIG) tool. A novel low cost laboratory based S-band (2.4GHz) PolSAR instrument is developed that is capable of capturing 4 channel fully polarimetric SAR image data. Simple radar targets are formed and system calibration is performed in terms of radar cross-section. Experimental measurements are done using combination of the PolSAR instrument with visible light polarimetric imager for scenes capturing basic scattering mechanisms for phenomenology studies. The three major scattering mechanisms studied in this research include single, double and multiple bounce. Single

  19. Interference Mitigation Effects on Synthetic Aperture Radar Coherent Data Products

    SciTech Connect

    Musgrove, Cameron

    2015-07-01

    For synthetic aperture radars radio frequency interference from sources external to the radar system and techniques to mitigate the interference can degrade the quality of the image products. Usually the radar system designer will try to balance the amount of mitigation for an acceptable amount of interference to optimize the image quality. This dissertation examines the effect of interference mitigation upon coherent data products of fine resolution, high frequency synthetic aperture radars using stretch processing. Novel interference mitigation techniques are introduced that operate on single or multiple apertures of data that increase average coherence compared to existing techniques. New metrics are applied to evaluate multiple mitigation techniques for image quality and average coherence. The underlying mechanism for interference mitigation techniques that affect coherence is revealed.

  20. Synthetic Aperture Radar Missions Study Report

    NASA Technical Reports Server (NTRS)

    Bard, S.

    2000-01-01

    This report reviews the history of the LightSAR project and summarizes actions the agency can undertake to support industry-led efforts to develop an operational synthetic aperture radar (SAR) capability in the United States.

  1. Contour-Mapping Synthetic-Aperture Radar

    NASA Technical Reports Server (NTRS)

    Goldstein, R. M.; Caro, E. R.; Wu, C.

    1985-01-01

    Airborne two-antenna synthetic-aperture-radar (SAR) interferometric system provides data processed to yield terrain elevation as well as reflectedintensity information. Relative altitudes of terrain points measured to within error of approximately 25 m.

  2. Space shuttle search and rescue experiment using synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Sivertson, W. E., Jr.; Larson, R. W.; Zelenka, J. S.

    1977-01-01

    The feasibility of a synthetic aperture radar for search and rescue applications was demonstrated with aircraft experiments. One experiment was conducted using the ERIM four-channel radar and several test sites in the Michigan area. In this test simple corner-reflector targets were successfully imaged. Results from this investigation were positive and indicate that the concept can be used to investigate new approaches focused on the development of a global search and rescue system. An orbital experiment to demonstrate the application of synthetic aperture radar to search and rescue is proposed using the space shuttle.

  3. Hughes integrated synthetic aperture radar: High performance at low cost

    SciTech Connect

    Bayma, R.W.

    1996-11-01

    This paper describes the background and development of the low cost high-performance Hughes Integrated Synthetic Aperture Radar (HISAR{trademark}) which has a full range of capabilities for real-time reconnaissance, surveillance and earth resource mapping. HISAR uses advanced Synthetic Aperture Radar (SAR) technology to make operationally effective images of near photo quality, day or night and in all weather conditions. This is achieved at low cost by maximizing the use of commercially available radar and signal-processing equipment in the fabrication. Furthermore, HISAR is designed to fit into an executive-class aircraft making it available for a wide range of users. 4 refs., 8 figs.

  4. Determination of the Wind-Velocity Vector Above the Ocean Surface Using the Image Spectrum of a Polarimetric Radar with Synthesized Aperture

    NASA Astrophysics Data System (ADS)

    Panfilova, M. A.; Kanevsky, M. B.; Balandina, G. N.; Karaev, V. Yu.; Stoffelen, A.; Verkhoev, A.

    2015-09-01

    We propose a new method for determining the wind-velocity vector above the ocean surface using the data of a polarimetric synthetic aperture radar. The preliminary calculations show that for wind waves, the location of the maximum in the radar image is unambiguously related to the wind velocity, whereas the wind direction is retrieved with an uncertainty of 180°, which is related to the central symmetry of the image spectrum. To eliminate the ambiguity when determining the wind direction, a criterion based on the information on the sign of the coefficient of correlation among the complex signals on the co- and cross polarizations is used. It is shown that using the polarimetric radar, it is theoretically possible to obtain information on both the wind velocity and direction without exact radar calibration.

  5. Georeferencing on Synthetic Aperture Radar Imagery

    NASA Astrophysics Data System (ADS)

    Esmaeilzade, M.; Amini, J.; Zakeri, S.

    2015-12-01

    Due to the SAR1 geometry imaging, SAR images include geometric distortions that would be erroneous image information and the images should be geometrically calibrated. As the radar systems are side looking, geometric distortion such as shadow, foreshortening and layover are occurred. To compensate these geometric distortions, information about sensor position, imaging geometry and target altitude from ellipsoid should be available. In this paper, a method for geometric calibration of SAR images is proposed. The method uses Range-Doppler equations. In this method, for the image georeferencing, the DEM2 of SRTM with 30m pixel size is used and also exact ephemeris data of the sensor is required. In the algorithm proposed in this paper, first digital elevation model transmit to range and azimuth direction. By applying this process, errors caused by topography such as foreshortening and layover are removed in the transferred DEM. Then, the position of the corners on original image is found base on the transferred DEM. Next, original image registered to transfer DEM by 8 parameters projective transformation. The output is the georeferenced image that its geometric distortions are removed. The advantage of the method described in this article is that it does not require any control point as well as the need to attitude and rotational parameters of the sensor. Since the ground range resolution of used images are about 30m, the geocoded images using the method described in this paper have an accuracy about 20m (subpixel) in planimetry and about 30m in altimetry. 1 Synthetic Aperture Radar 2 Digital Elevation Model

  6. Comparative analysis for detecting areas with building damage from several destructive earthquakes using satellite synthetic aperture radar images

    NASA Astrophysics Data System (ADS)

    Matsuoka, Masashi; Yamazaki, Fumio

    2010-11-01

    Earthquakes that have caused large-scale damage in developed areas, such as the 1994 Northridge and 1995 Kobe events, remind us of the importance of making quick damage assessments in order to facilitate the resumption of normal activities and restoration planning. Synthetic aperture radar (SAR) can be used to record physical aspects of the Earth's surface under any weather conditions, making it a powerful tool in the development of an applicable method for assessing damage following natural disasters. Detailed building damage data recorded on the ground following the 1995 Kobe earthquake may provide an invaluable opportunity to investigate the relationship between the backscattering properties and the degree of damage. This paper aims to investigate the differences between the backscattering coefficients and the correlations derived from pre- and post-earthquake SAR intensity images to smoothly detect areas with building damage. This method was then applied to SAR images recorded over the areas affected by the 1999 Kocaeli earthquake in Turkey, the 2001 Gujarat earthquake in India, and the 2003 Boumerdes earthquake in Algeria. The accuracy of the proposed method was examined and confirmed by comparing the results of the SAR analyses with the field survey data.

  7. Exploiting Decorrelations In Synthetic-Aperture Radar

    NASA Technical Reports Server (NTRS)

    Zebker, Howard A.; Villasenor, John D.

    1994-01-01

    Temporal decorrelation between synthetic-aperture-radar data acquired on subsequent passes along same or nearly same trajectory serves as measure of change in target scene. Based partly on mathematical models of statistics of correlations between first- and second-pass radar echoes. Also based partly on Fourier-transform relations between radar-system impulse response and decorrelation functions particularly those expressing decorrelation effects of rotation and horizontal shift of trajectories between two passes.

  8. Space shuttle search and rescue experiment using synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Sivertson, W. E., Jr.; Larson, R. W.; Zelenka, J. S.

    1977-01-01

    Langley Research Center, NASA, is developing a concept for using a spaceborne synthetic aperture radar with passive reflectors for search and rescue applications. The feasibility of a synthetic aperture radar for search and rescue applications has been demonstrated with aircraft experiments. One experiment was conducted using the ERIM four-channel radar and several test sites in the Michigan area. In this test simple corner-reflector targets were successfully imaged. Results from this investigation were positive and indicate that the concept can be used to investigate new approaches focused on the development of a global search and rescue system. An orbital experiment to demonstrate the application of synthetic aperture radar to search and rescue is proposed using the space shuttle.

  9. The effects of snow on landmarks in K/sub u/ band SAR (Synthetic Aperture Radar) images

    SciTech Connect

    Murrary, M.

    1989-04-01

    This report documents research into the effects of snow on candidate landmarks for the TFS radar. It includes a discussion of a simple snow model, relevant backscatter data from previous ground based collections, predictions of the effects of snow coverage based on this data, a discussion of the snow data collection with the TFS radar, and an analysis of the results of that collection. All SAR images are for a K/sub u/ band radar, with HH polarization, and a 30/degree/ depression angle. The images have three meter resolution and a one kilometer swath. SAR images were collected of both rural and urban landmarks. 5 refs., 7 figs., 19 tabs.

  10. Eliminating Clutter in Synthetic-Aperture Radar

    NASA Technical Reports Server (NTRS)

    Jain, A.

    1979-01-01

    Diffusion technique reduces clutter noise in coherent SAR (synthetic-aperature radar) image signal without degrading its resolution. Technique makes radar-mapped terrain features more obvious.It also has potential application in holographic microscopy.

  11. A new sparse Bayesian learning method for inverse synthetic aperture radar imaging via exploiting cluster patterns

    NASA Astrophysics Data System (ADS)

    Fang, Jun; Zhang, Lizao; Duan, Huiping; Huang, Lei; Li, Hongbin

    2016-05-01

    The application of sparse representation to SAR/ISAR imaging has attracted much attention over the past few years. This new class of sparse representation based imaging methods present a number of unique advantages over conventional range-Doppler methods, the basic idea behind these works is to formulate SAR/ISAR imaging as a sparse signal recovery problem. In this paper, we propose a new two-dimensional pattern-coupled sparse Bayesian learning(SBL) method to capture the underlying cluster patterns of the ISAR target images. Based on this model, an expectation-maximization (EM) algorithm is developed to infer the maximum a posterior (MAP) estimate of the hyperparameters, along with the posterior distribution of the sparse signal. Experimental results demonstrate that the proposed method is able to achieve a substantial performance improvement over existing algorithms, including the conventional SBL method.

  12. Speckle reduction in synthetic-aperture-radar imagery.

    PubMed

    Harvey, E R; April, G V

    1990-07-01

    Speckle appearing in synthetic-aperture-radar images degrades the information contained in these images. Speckle noise can be suppressed by adapted local processing techniques, permitting the definition of statistical parameters inside a small window centered on each pixel of the image. Two processing algorithms are examined; the first one uses the intensity as a variable, and the second one works on a homomorphic transformation of the image intensity. A statistical model for speckle noise that takes into account correlation in multilook imagery has been used to develop these processing algorithms. Several experimental results of processed Seasat-A syntheticaperture-radar images are discussed. PMID:19768064

  13. Synthetic aperture radar processing with polar formatted subapertures

    SciTech Connect

    Doerry, A.W.

    1994-10-01

    Synthetic Aperture Radar (SAR) uses the motion of a small real antenna to synthesize a larger aperture, and thereby achieve very fine azimuth resolution. Efficient SAR image formation requires modelling the radar echo and compensating (focusing) the delay and phase for various positions in the target scene. Polar-Format processing is one successful algorithm developed to process large scenes at fine resolutions, but is still limited, especially at resolutions near a wavelength. This paper shows how using tiers of subapertures can overcome the limitations of Polar-Format processing and increase the focused scene size substantially while using only efficient vector multiplies and Fast Fourier Transforms.

  14. Coastal Monitoring Using L-band Synthetic Aperture Radar (SAR) Image Data - Some Case Studies in Asian Delta Areas

    NASA Astrophysics Data System (ADS)

    Tanaka, A.

    2014-12-01

    Coastal geomorphology is highly variable as it is affected by sea-level changes and other naturally- and human-induced fluctuations. To effectively assess and monitor geomorphological changes in various time scales is thus critical for coastal management. Asian mega deltas are vulnerable to a sea-level rise due to its low-lying delta plain, and are dynamic region given a large amount of sediment supply. However, limited data availability and accessibility in the deltas have prevented establishment of systematic coastal monitoring. A variety of remote sensing systems can be used to monitor geomorphological changes in coastal areas as it has wide spatial coverage and high temporal repeatability. Especially, analysis using SAR (Synthetic Aperture Radar) data not affected by the cloud conditions offer potential for monitoring in the monsoon Asia region. We will present some case studies of Asian coastal regions using L-band SAR data, ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array type L-band SAR) and JERS-1 (Japanese Earth Resource Satellite-1) SAR data. One example is that time-series of radar amplitude images can be used to delineate changes quantitatively of the areal extent of river-mouth bars in distributaries of the Mekong River delta. It shows that the estimated areas of river mouthbars gradually increase on an annual time scale, and seasonal variations of areas were also recognized. Another example is that differential SAR interferometry is applied to the coast of the Yellow River delta in China. It shows very high subsidence rates, likely due to groundwater pumping. A further example is that we apply a SAR interferometry time series analysis to monitor ground deformations in the lower Chao Phraya delta plain, Thailand. A single reference time series interferogram from the stacking of unwrapped phases were applied. The subsidence and uplift pattern observed using the SAR interferometry time series analysis highlights the spatial complexity

  15. Computer simulation of the effects of a distributed array antenna on synthetic aperture radar images

    NASA Technical Reports Server (NTRS)

    Estes, J. M.

    1985-01-01

    The ARL:UT orbital SAR simulation has been upgraded to use three-dimensional antenna gain patterns. This report describes the modifications and presents quantitative image analyses of a simulation using antenna patterns generated from the modeling of a distributed array antenna.

  16. Digital interpolators for polar format processing. [of synthetic aperture radar images

    NASA Technical Reports Server (NTRS)

    Adams, John W.; Hudson, Ralph E.; Bayma, Robert W.; Nelson, Jeffrey E.

    1989-01-01

    The polar format approach to SAR image formation requires data to be interpolated from a warped grid onto a Cartesian lattice. In general, this requires that data be interpolated between varying sampling rates. In this paper, frequency-domain optimality criteria for polar format interpolators are defined and justified, and an approach to designing the corresponding digital filters is described.

  17. Remote sensing of the ocean waveheight spectrum using synthetic-aperture-radar images

    NASA Technical Reports Server (NTRS)

    Vesecky, J. F.; Assal, H. M.; Stewart, R. H.

    1981-01-01

    The paper discusses problems in the detection and measurement of ocean waves from their SAR images, in particular the measurement of the wavenumber spectrum of ocean-wave-height fluctuations. Comparisons on a limited set of pitch-roll buoy and SEASAT SAR measurements during the 1978 JASIN experiment reveal that degradation of SAR resolution caused by wave orbital motion is a crucial factor in the detection of waves by SAR images. Thus, waves with small slopes traveling perpendicular to the SAR flight path are more easily detected than waves with large slopes traveling along the flight path. Although the SAR estimates in this comparison were found to contain significant biases, they were in rough agreement with buoy measurements, provided the ocean wavelength was between about 120 and 400 m and the ocean wave direction was not approximately along the SAR flight path.

  18. Theory for synthetic aperture radar imaging of the ocean surface - With application to the Tower Ocean Wave and Radar Dependence experiment on focus, resolution, and wave height spectra

    NASA Astrophysics Data System (ADS)

    Kasilingam, Dayalan P.; Shemdin, Omar H.

    1988-11-01

    A one-dimensional model for simulating azimuthal SAR imaging of the ocean surface is developed which can admit both the 'distributed surface' and 'velocity bunching' approaches. Computer simulations demonstrate that the time-dependent modulation patterns due to the radar cross section variation and the velocity bunching effects provide optimum focusing around half the phase velocity of the long wave. The results indicate that in the Tower Ocean Wave and Radar Dependence experiment, SAR imaging at L band is approximately linear.

  19. Theory for synthetic aperture radar imaging of the ocean surface - With application to the Tower Ocean Wave and Radar Dependence experiment on focus, resolution, and wave height spectra

    NASA Technical Reports Server (NTRS)

    Kasilingam, Dayalan P.; Shemdin, Omar H.

    1988-01-01

    A one-dimensional model for simulating azimuthal SAR imaging of the ocean surface is developed which can admit both the 'distributed surface' and 'velocity bunching' approaches. Computer simulations demonstrate that the time-dependent modulation patterns due to the radar cross section variation and the velocity bunching effects provide optimum focusing around half the phase velocity of the long wave. The results indicate that in the Tower Ocean Wave and Radar Dependence experiment, SAR imaging at L band is approximately linear.

  20. Time-frequency analysis of synthetic aperture radar signals

    SciTech Connect

    Johnston, B.

    1996-08-01

    Synthetic aperture radar (SAR) has become an important tool for remote sensing of the environment. SAR is a set of digital signal processing algorithms that are used to focus the signal returned to the radar because radar systems in themselves cannot produce the high resolution images required in remote sensing applications. To reconstruct an image, several parameters must be estimated and the quality of output image depends on the degree of accuracy of these parameters. In this thesis, we derive the fundamental SAR algorithms and concentrate on the estimation of one of its critical parameters. We show that the common technique for estimating this particular parameter can sometimes lead to erroneous results and reduced quality images. We also employ time-frequency analysis techniques to examine variations in the radar signals caused by platform motion and show how these results can be used to improve output image quality.

  1. Processing for spaceborne synthetic aperture radar imagery

    NASA Technical Reports Server (NTRS)

    Lybanon, M.

    1973-01-01

    The data handling and processing in using synthetic aperture radar as a satellite-borne earth resources remote sensor is considered. The discussion covers the nature of the problem, the theory, both conventional and potential advanced processing techniques, and a complete computer simulation. It is shown that digital processing is a real possibility and suggests some future directions for research.

  2. Azimuth correlator for real-time synthetic aperture radar image processing

    NASA Technical Reports Server (NTRS)

    Arens, W. E. (Inventor)

    1979-01-01

    An azimuth correlator architecture is defined wherein a number of serial range-line buffer memories are cascaded such that the output stages of all buffer memories together form a complete and unique range bin in the azimuthal dimension at any given time. A range bin is automatically read out of the last stages of the registers in parallel on a range line sample-by-sample basis for subsequent range migration correction and correlation. Range migration correction is performed on the range bins by effectively varying the length of a delay register at the output of each range-line buffer memory. The corrected range bin output from the delay registers is then correlated with a Doppler reference function to form an image element on a real-time basis.

  3. Optical synthetic-aperture radar processor archietecture with quadratic phase-error correction

    SciTech Connect

    Dickey, F.M.; Mason, J.J. )

    1990-10-15

    Uncompensated phase errors limit the image quality of synthetic-aperture radar. We present an acousto-optic synthetic-aperture radar processor architecture capable of measuring the quadratic phase error. This architecture allows for the error signal to be fed back to the processor to generate the corrected image.

  4. Ionospheric effects on synthetic aperture radar at VHF

    SciTech Connect

    Fitzgerald, T.J.

    1997-02-01

    Synthetic aperture radars (SAR) operated from airplanes have been used at VHF because of their enhanced foliage and ground penetration compared to radars operated at UHF. A satellite-borne VHF SAR would have considerable utility but in order to operate with high resolution it would have to use both a large relative bandwidth and a large aperture. The presence of the ionosphere in the propagation path of the radar will cause a deterioration of the imaging because of dispersion over the bandwidth and group path changes in the imaged area over the collection aperture. In this paper we present calculations of the effects of a deterministic ionosphere on SAR imaging for a radar operated with a 100 MHz bandwidth centered at 250 MHz and over an angular aperture of 23{degrees}. The ionosphere induces a point spread function with an approximate half-width of 150 m in the slant-range direction and of 25 m in the cross-range direction compared to the nominal resolution of 1.5 m in both directions.

  5. Interferometric synthetic aperture radar imagery of the Gulf Stream

    NASA Technical Reports Server (NTRS)

    Ainsworth, T. L.; Cannella, M. E.; Jansen, R. W.; Chubb, S. R.; Carande, R. E.; Foley, E. W.; Goldstein, R. M.; Valenzuela, G. R.

    1993-01-01

    The advent of interferometric synthetic aperture radar (INSAR) imagery brought to the ocean remote sensing field techniques used in radio astronomy. Whilst details of the interferometry differ between the two fields, the basic idea is the same: Use the phase information arising from positional differences of the radar receivers and/or transmitters to probe remote structures. The interferometric image is formed from two complex synthetic aperture radar (SAR) images. These two images are of the same area but separated in time. Typically the time between these images is very short -- approximately 50 msec for the L-band AIRSAR (Airborne SAR). During this short period the radar scatterers on the ocean surface do not have time to significantly decorrelate. Hence the two SAR images will have the same amplitude, since both obtain the radar backscatter from essentially the same object. Although the ocean surface structure does not significantly decorrelate in 50 msec, surface features do have time to move. It is precisely the translation of scattering features across the ocean surface which gives rise to phase differences between the two SAR images. This phase difference is directly proportional to the range velocity of surface scatterers. The constant of proportionality is dependent upon the interferometric mode of operation.

  6. The SEASAT-A synthetic aperture radar design and implementation

    NASA Technical Reports Server (NTRS)

    Jordan, R. L.

    1978-01-01

    The SEASAT-A synthetic aperture imaging radar system is the first imaging radar system intended to be used as a scientific instrument designed for orbital use. The requirement of the radar system is to generate continuous radar imagery with a 100 kilometer swath with 25 meter resolution from an orbital altitude of 800 kilometers. These requirements impose unique system design problems and a description of the implementation is given. The end-to-end system is described, including interactions of the spacecraft, antenna, sensor, telemetry link, recording subsystem, and data processor. Some of the factors leading to the selection of critical system parameters are listed. The expected error sources leading to degradation of image quality are reported as well as estimate given of the expected performance from data obtained during a ground testing of the completed subsystems.

  7. Optical sparse aperture imaging.

    PubMed

    Miller, Nicholas J; Dierking, Matthew P; Duncan, Bradley D

    2007-08-10

    The resolution of a conventional diffraction-limited imaging system is proportional to its pupil diameter. A primary goal of sparse aperture imaging is to enhance resolution while minimizing the total light collection area; the latter being desirable, in part, because of the cost of large, monolithic apertures. Performance metrics are defined and used to evaluate several sparse aperture arrays constructed from multiple, identical, circular subapertures. Subaperture piston and/or tilt effects on image quality are also considered. We selected arrays with compact nonredundant autocorrelations first described by Golay. We vary both the number of subapertures and their relative spacings to arrive at an optimized array. We report the results of an experiment in which we synthesized an image from multiple subaperture pupil fields by masking a large lens with a Golay array. For this experiment we imaged a slant edge feature of an ISO12233 resolution target in order to measure the modulation transfer function. We note the contrast reduction inherent in images formed through sparse aperture arrays and demonstrate the use of a Wiener-Helstrom filter to restore contrast in our experimental images. Finally, we describe a method to synthesize images from multiple subaperture focal plane intensity images using a phase retrieval algorithm to obtain estimates of subaperture pupil fields. Experimental results from synthesizing an image of a point object from multiple subaperture images are presented, and weaknesses of the phase retrieval method for this application are discussed. PMID:17694146

  8. Confocal coded aperture imaging

    DOEpatents

    Tobin, Jr., Kenneth William; Thomas, Jr., Clarence E.

    2001-01-01

    A method for imaging a target volume comprises the steps of: radiating a small bandwidth of energy toward the target volume; focusing the small bandwidth of energy into a beam; moving the target volume through a plurality of positions within the focused beam; collecting a beam of energy scattered from the target volume with a non-diffractive confocal coded aperture; generating a shadow image of said aperture from every point source of radiation in the target volume; and, reconstructing the shadow image into a 3-dimensional image of the every point source by mathematically correlating the shadow image with a digital or analog version of the coded aperture. The method can comprise the step of collecting the beam of energy scattered from the target volume with a Fresnel zone plate.

  9. Recent advances in airborne terrestrial remote sensing with the NASA airborne visible/infrared imaging spectrometer (AVIRIS), airborne synthetic aperture radar (SAR), and thermal infrared multispectral scanner (TIMS)

    NASA Technical Reports Server (NTRS)

    Vane, Gregg; Evans, Diane L.; Kahle, Anne B.

    1989-01-01

    Significant progress in terrestrial remote sensing from the air has been made with three NASA-developed sensors that collectively cover the solar-reflected, thermal infrared, and microwave regions of the electromagnetic spectrum. These sensors are the airborne visible/infrared imaging spectrometer (AVIRIS), the thermal infrared mapping spectrometer (TIMS) and the airborne synthetic aperture radar (SAR), respectively. AVIRIS and SAR underwent extensive in-flight engineering testing in 1987 and 1988 and are scheduled to become operational in 1989. TIMS has been in operation for several years. These sensors are described.

  10. Synthetic aperture radar interferometry of Okmok volcano, Alaska: radar observations

    USGS Publications Warehouse

    Lu, Zhong; Mann, Dörte; Freymueller, Jeffrey T.; Meyer, David

    2000-01-01

    ERS-1/ERS-2 synthetic aperture radar interferometry was used to study the 1997 eruption of Okmok volcano in Alaska. First, we derived an accurate digital elevation model (DEM) using a tandem ERS-1/ERS-2 image pair and the preexisting DEM. Second, by studying changes in interferometric coherence we found that the newly erupted lava lost radar coherence for 5-17 months after the eruption. This suggests changes in the surface backscattering characteristics and was probably related to cooling and compaction processes. Third, the atmospheric delay anomalies in the deformation interferograms were quantitatively assessed. Atmospheric delay anomalies in some of the interferograms were significant and consistently smaller than one to two fringes in magnitude. For this reason, repeat observations are important to confidently interpret small geophysical signals related to volcanic activities. Finally, using two-pass differential interferometry, we analyzed the preemptive inflation, coeruptive deflation, and posteruptive inflation and confirmed the observations using independent image pairs. We observed more than 140 cm of subsidence associated with the 1997 eruption. This subsidence occurred between 16 months before the eruption and 5 months after the eruption, was preceded by ∼18 cm of uplift between 1992 and 1995 centered in the same location, and was followed by ∼10 cm of uplift between September 1997 and 1998. The best fitting model suggests the magma reservoir resided at 2.7 km depth beneath the center of the caldera, which was ∼5 km from the eruptive vent. We estimated the volume of the erupted material to be 0.055 km3 and the average thickness of the erupted lava to be ∼7.4 m. Copyright 2000 by the American Geophysical Union.

  11. Performance limits for Synthetic Aperture Radar.

    SciTech Connect

    Doerry, Armin Walter

    2006-02-01

    The performance of a Synthetic Aperture Radar (SAR) system depends on a variety of factors, many which are interdependent in some manner. It is often difficult to ''get your arms around'' the problem of ascertaining achievable performance limits, and yet those limits exist and are dictated by physics, no matter how bright the engineer tasked to generate a system design. This report identifies and explores those limits, and how they depend on hardware system parameters and environmental conditions. Ultimately, this leads to a characterization of parameters that offer optimum performance for the overall SAR system. For example, there are definite optimum frequency bands that depend on weather conditions and range, and minimum radar PRF for a fixed real antenna aperture dimension is independent of frequency. While the information herein is not new to the literature, its collection into a single report hopes to offer some value in reducing the ''seek time''.

  12. A perspective of synthetic aperture radar for remote sensing

    NASA Technical Reports Server (NTRS)

    Skolnik, M. I.

    1978-01-01

    The characteristics and capabilities of synthetic aperture radar are discussed so as to identify those features particularly unique to SAR. The SAR and Optical images were compared. The SAR is an example of radar that provides more information about a target than simply its location. It is the spatial resolution and imaging capability of SAR that has made its application of interest, especially from spaceborne platforms. However, for maximum utility to remote sensing, it was proposed that other information be extracted from SAR data, such as the cross section with frequency and polarization.

  13. Linear Dispersion Relation and Depth Sensitivity to Swell Parameters: Application to Synthetic Aperture Radar Imaging and Bathymetry

    PubMed Central

    Boccia, Valentina; Renga, Alfredo; Rufino, Giancarlo; D'Errico, Marco; Moccia, Antonio; Aragno, Cesare; Zoffoli, Simona

    2015-01-01

    Long gravity waves or swell dominating the sea surface is known to be very useful to estimate seabed morphology in coastal areas. The paper reviews the main phenomena related to swell waves propagation that allow seabed morphology to be sensed. The linear dispersion is analysed and an error budget model is developed to assess the achievable depth accuracy when Synthetic Aperture Radar (SAR) data are used. The relevant issues and potentials of swell-based bathymetry by SAR are identified and discussed. This technique is of particular interest for characteristic regions of the Mediterranean Sea, such as in gulfs and relatively close areas, where traditional SAR-based bathymetric techniques, relying on strong tidal currents, are of limited practical utility. PMID:25789333

  14. Linear dispersion relation and depth sensitivity to swell parameters: application to synthetic aperture radar imaging and bathymetry.

    PubMed

    Boccia, Valentina; Renga, Alfredo; Rufino, Giancarlo; D'Errico, Marco; Moccia, Antonio; Aragno, Cesare; Zoffoli, Simona

    2015-01-01

    Long gravity waves or swell dominating the sea surface is known to be very useful to estimate seabed morphology in coastal areas. The paper reviews the main phenomena related to swell waves propagation that allow seabed morphology to be sensed. The linear dispersion is analysed and an error budget model is developed to assess the achievable depth accuracy when Synthetic Aperture Radar (SAR) data are used. The relevant issues and potentials of swell-based bathymetry by SAR are identified and discussed. This technique is of particular interest for characteristic regions of the Mediterranean Sea, such as in gulfs and relatively close areas, where traditional SAR-based bathymetric techniques, relying on strong tidal currents, are of limited practical utility. PMID:25789333

  15. Analytic inversion in synthetic aperture radar.

    PubMed Central

    Rothaus, O S

    1994-01-01

    A method of processing synthetic aperture radar signals that avoids some of the approximations currently in use that appear to be responsible for severe phase distortions is described. As a practical matter, this method requires N3 numerical operations, as opposed to the N2 ln N currently the case, but N3 is now easily managed, for N in the range of interest. PMID:11607485

  16. Oil Slick Characterization Using Synthetic Aperture Radar

    NASA Astrophysics Data System (ADS)

    Jones, C. E.; Breivik, O.; Brekke, C.; Skrunes, S.; Holt, B.

    2015-12-01

    Oil spills are a hazard worldwide with potential of causing high impact disasters, and require an active oil spill response capability to protect personnel, the ecosystem, and the energy supply. As the amount of oil in traditionally accessible reserves decline, there will be increasing oil extraction from the Arctic and deep-water wells, both new sources with high risk and high cost for monitoring and response. Although radar has long been used for mapping the spatial extent of oil slicks, it is only since the Deepwater Horizon spill that synthetic aperture radar (SAR) has been shown capable of characterizing oil properties within a slick, and therefore useful for directing response to the recoverable thicker slicks or emulsions. Here we discuss a 2015 Norwegian oil-on-water spill experiment in which emulsions of known quantity and water-to-oil ratio along with a look-alike slick of plant oil were released in the North Sea and imaged with polarimetric SAR (PolSAR) by NASA's UAVSAR instrument for several hours following release. During the experiment, extensive in situ measurements were made from ship or aircraft with meteorological instruments, released drift buoys, and optical/IR imagers. The experiment was designed to provide validation data for development of a physical model relating polarization-dependent electromagnetic scattering to the dielectric properties of oil mixed with ocean water, which is the basis for oil characterization with SAR. Data were acquired with X-, C-, and L-band satellite-based SARs to enable multi-frequency comparison of characterization capabilities. In addition, the data are used to develop methods to differentiate mineral slicks from biogenic look-alikes, and to better understand slick weathering and dispersion. The results will provide a basis for modeling oil-in-ice spills, currently a high priority for nations involved in Arctic oil exploration. Here we discuss the Norwegian experiment, the validation data, and the results of

  17. Radar imaging of the ocean surface

    NASA Technical Reports Server (NTRS)

    Elachi, C.

    1978-01-01

    Techniques for obtaining radar images of the ocean surface are briefly described, and examples of radar images of a variety of ocean surface wave types obtained by synthetic-aperture radar are presented and discussed. Observations described include deep-ocean waves, discrete wave trains, internal waves as surface manifestations, slicks, and eddies.

  18. Probing the Martian Subsurface with Synthetic Aperture Radar

    NASA Technical Reports Server (NTRS)

    Campbell, B. A.; Maxwell, T. A.; Freeman, A.

    2005-01-01

    Many regions of the martian surface are covered by fine-grained materials emplaced by volcanic, fluvial, or aeolian processes. These mantling deposits likely hide ancient channel systems (particularly at smaller scale lengths) and volcanic, impact, glacial, or shoreline features. Synthetic aperture radar (SAR) offers the capability to probe meters below the surface, with imaging resolution in the 10 s of m range, to reveal the buried terrain and enhance our understanding of Mars geologic and climate history. This presentation focuses on the practical applications of a Mars orbital SAR, methods for polarimetric and interferometric radar studies, and examples of such techniques for Mars-analog sites on the Moon and Earth.

  19. Synthetic aperture radar and digital processing: An introduction

    NASA Technical Reports Server (NTRS)

    Dicenzo, A.

    1981-01-01

    A tutorial on synthetic aperture radar (SAR) is presented with emphasis on digital data collection and processing. Background information on waveform frequency and phase notation, mixing, Q conversion, sampling and cross correlation operations is included for clarity. The fate of a SAR signal from transmission to processed image is traced in detail, using the model of a single bright point target against a dark background. Some of the principal problems connected with SAR processing are also discussed.

  20. Improving the TanDEM-X DEM for flood modelling using flood extents from Synthetic Aperture Radar images.

    NASA Astrophysics Data System (ADS)

    Mason, David; Trigg, Mark; Garcia-Pintado, Javier; Cloke, Hannah; Neal, Jeffrey; Bates, Paul

    2015-04-01

    reduced errors on the refined waterline heights. The method was tested on a section of the TanDEM-X Intermediate DEM (IDEM) covering an 11km reach of the Warwickshire Avon, England. Flood extents from four COSMO-SKyMed images were available at various stages of a flood in November 2012. Waterlines were detected automatically using the method described in [1]. The 12.5m resolution IDEM was re-sampled to the 2.5m resolution of the CSK images using nearest neighbour interpolation. Improvements to the IDEM were attempted only in regions of low slope and low vegetation, so that the DEM could be regarded as the DTM. The height of a pixel on a waterline was replaced by the average of the waterline pixel heights in an 11 x 11 IDEM pixel window centred on the current CSK pixel (but selecting only one waterline height per IDEM pixel to reduce correlations). Original and refined IDEM heights were compared to corresponding airborne LiDAR heights. Along the waterlines, it was found that the original IDEM heights had a standard deviation of 1.1m and a bias of 0.2m, while the refined heights had a standard deviation of only 0.6m and a similar bias. Between two adjacent waterlines, on average approximately 25% of IDEM heights were above the higher waterline, and 20% below the lower waterline. When compared to LiDAR, the original higher heights had a mean difference from the LiDAR height of 2.4m with standard deviation 3.0m, while after correction the mean difference was 0.5m with standard deviation 1.0m. The corrected heights below the lower waterline were similarly improved. The height errors of a further 40% of IDEM heights between the higher and lower waterlines were also reduced, because of the reduced errors on the refined waterline heights. 1. Mason DC, Davenport IJ, Neal JC, Schumann GJ-P and Bates PD (2012). Near real-time flood detection in urban and rural areas using high resolution Synthetic Aperture Radar images. IEEE. Trans. Geoscience Rem. Sens., 50(8), 3041-3052.

  1. SEASAT views oceans and sea ice with synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Fu, L. L.; Holt, B.

    1982-01-01

    Fifty-one SEASAT synthetic aperture radar (SAR) images of the oceans and sea ice are presented. Surface and internal waves, the Gulf Stream system and its rings and eddies, the eastern North Pacific, coastal phenomena, bathymetric features, atmospheric phenomena, and ship wakes are represented. Images of arctic pack and shore-fast ice are presented. The characteristics of the SEASAT SAR system and its image are described. Maps showing the area covered, and tables of key orbital information, and listing digitally processed images are provided.

  2. Analysis of synthetic aperture radar imagery

    NASA Technical Reports Server (NTRS)

    Blanchard, B. J. (Principal Investigator)

    1976-01-01

    The author has identified the following significant results. Average radar response for L-band like polarized system appeared to be related to the watershed runoff coefficients when the viewing angle was approximately 42 deg off nadir. Four requirements for radar systems used to verify applications of active microwave for water resources were identified: (1) first generation digital data will be required; (2) radar should be calibrated both internally and externally; (3) new systems should avoid radom use; and (4) images should be geometrically rectified prior to delivery to the user.

  3. Digital exploitation of synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Wagner, H. L.; Shuchman, R. A.

    1977-01-01

    A digital processing and analysis scheme for use with digitized synthetic aperture radar data was developed. Using data from a four channel system, the imagery is preprocessed using specially designed software and then analyzed using preexisting facilities originally intended for use with MSS type data. Geometric and radiometric correction may be performed if desired, as well as classification analysis, Fast Fourier transform, filtering and level slice and display functions. The system provides low cost output in real time, permitting interactive imagery analysis. System information flow diagrams as well as sample output products are shown.

  4. Interference Mitigation Effects on Synthetic Aperture Radar Coherent Data Products

    SciTech Connect

    Musgrove, Cameron

    2014-05-01

    For synthetic aperture radar image products interference can degrade the quality of the images while techniques to mitigate the interference also reduce the image quality. Usually the radar system designer will try to balance the amount of mitigation for the amount of interference to optimize the image quality. This may work well for many situations, but coherent data products derived from the image products are more sensitive than the human eye to distortions caused by interference and mitigation of interference. This dissertation examines the e ect that interference and mitigation of interference has upon coherent data products. An improvement to the standard notch mitigation is introduced, called the equalization notch. Other methods are suggested to mitigation interference while improving the quality of coherent data products over existing methods.

  5. Motion Measurement for Synthetic Aperture Radar.

    SciTech Connect

    Doerry, Armin W.

    2015-01-01

    Synthetic Aperture Radar (SAR) measures radar soundings from a set of locations typically along the flight path of a radar platform vehicle. Optimal focusing requires precise knowledge of the sounding source locations in 3 - D space with respect to the target scene. Even data driven focusing techniques (i.e. autofocus) requires some degree of initial fidelity in the measurements of the motion of the radar. These requirements may be quite stringent especially for fine resolution, long ranges, and low velocities. The principal instrument for measuring motion is typically an Inertial Measurement Unit (IMU), but these instruments have inherent limi ted precision and accuracy. The question is %22How good does an IMU need to be for a SAR across its performance space?%22 This report analytically relates IMU specifications to parametric requirements for SAR. - 4 - Acknowledgements Th e preparation of this report is the result of a n unfunded research and development activity . Although this report is an independent effort, it draws heavily from limited - release documentation generated under a CRADA with General Atomics - Aeronautical System, Inc. (GA - ASI), and under the Joint DoD/DOE Munitions Program Memorandum of Understanding. Sandia National Laboratories is a multi - program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of En ergy's National Nuclear Security Administration under contract DE - AC04 - 94AL85000.

  6. New military uses for synthetic aperture radar (SAR)

    NASA Astrophysics Data System (ADS)

    Reamer, Richard E.; Stockton, Wayne; Stromfors, Richard D.

    1993-02-01

    Loral Defense Systems-Arizona, holder of the original patent for the invention of Synthetic Aperture Radar (SAR), developed SAR to meet the military's need for an all-weather, day/night sensor that could produce high quality reconnaissance imagery in adverse weather and restricted visibility conditions. These features, and the ability to image large areas with fine resolution in a relatively short period of time make this sensor useful for many military applications. To date, however, SARs for military use have been hampered by the fact that they've been large, complex, and expensive. Additionally, they have been mounted on special purpose, single mission aircraft which are costly to operate. That situation has changed. A small, modular SAR, called Miniature Synthetic Aperture Radar (MSAR) developed by Loral can be mounted with relative ease on Unmanned Aerial Vehicles (UAV) or on multi-mission aircraft such as the F-16, F/A-18, or on the F-14.

  7. Short-range ground-based synthetic aperture radar imaging: performance comparison between frequency-wavenumber migration and back-projection algorithms

    NASA Astrophysics Data System (ADS)

    Yigit, Enes; Demirci, Sevket; Özdemir, Caner; Tekbaş, Mustafa

    2013-01-01

    Two popular synthetic aperture radar (SAR) reconstruction algorithms, namely the back-projection (BP) and the frequency wavenumber (ω-k) algorithms, were tested and compared against each other, especially for their use in ground-based (GB) SAR applications directed to foreign object debris removal. For this purpose, an experimental setup in a semi-anechoic chamber room was accomplished to obtain near-field SAR images of objects on the ground. Then, the 90 to 95 GHz scattering data were acquired by using a stepped frequency continuous-wave radar operation. The performances of the setup and the imaging algorithms were then assessed by exploiting various metrics including point spread function, signal-to-clutter ratio, integrated side-lobe ratio, and computational complexity. Results demonstrate that although both algorithms produce almost accurate images of targets, the BP algorithm is shown to be superior to the ω-k algorithm due to its some inherent advantages specifically suited for short-range GB-SAR applications.

  8. Synthetic aperture radar and interferometry development at Sandia National Laboratories

    SciTech Connect

    1993-04-01

    Environmental monitoring, earth-resource mapping, and military systems require broad-area imaging at high resolutions. Many times the imagery must be acquired in inclement weather or during night as well as day. Synthetic aperture radar (SAR) provides such a capability. SAR systems take advantage of the long-range propagation characteristics of radar signals and the complex information processing capability of modern digital electronics to provide high resolution imagery. SAR complements photographic and other optical imaging capabilities because of the minimum constrains on time-of-day and atmospheric conditions and because of the unique responses of terrain and cultural targets to radar frequencies. Interferometry is a method for generating a three-dimensional image of terrain. The height projection is obtained by acquiring two SAR images from two slightly differing locations. It is different from the common method of stereoscopic imaging for topography. The latter relies on differing geometric projections for triangulation to define the surface geometry whereas interferometry relies on differences in radar propagation times between the two SAR locations. This paper presents the capabilities of SAR, explains how SAR works, describes a few SAR applications, provides an overview of SAR development at Sandia, and briefly describes the motion compensation subsystem.

  9. Interferometric synthetic aperture radar studies of Alaska volcanoes

    USGS Publications Warehouse

    Lu, Zhiming; Wicks, C., Jr.; Power, J.; Dzurisin, D.; Thatcher, W.; Masterlark, Timothy

    2002-01-01

    Interferometric synthetic aperture radar (InSAR) imaging is a recently developed geodetic technique capable of measuring ground-surface deformation with centimeter to subcentimeter vertical precision and spatial resolution of tens-of-meter over a relatively large region (???104 km2). The spatial distribution of surface deformation data, derived from InSAR images, enables the construction of detailed mechanical models to enhance the study of magmatic and tectonic processes associated with volcanoes. This paper summarizes our recent InSAR studies of several Alaska volcanoes, which include Okmok, Akutan, Kiska, Augustine, Westdahl, and Peulik volcanoes.

  10. Weighting in digital synthetic aperture radar processing

    NASA Technical Reports Server (NTRS)

    Dicenzo, A.

    1979-01-01

    Weighting is employed in synthetic aperture radar (SAR) processing to reduce the sidelobe response at the expense of peak center response height and mainlobe resolution. The weighting effectiveness in digital processing depends not only on the choice of weighting function, but on the fineness of sampling and quantization, on the time bandwidth product, on the quadratic phase error, and on the azimuth antenna pattern. The results of simulations conducted to uncover the effect of these parameters on azimuth weighting effectiveness are presented. In particular, it is shown that multilook capabilities of future SAR systems may obviate the need for consideration of the antenna pattern, and that azimuth time-bandwidth products of over 200 are probably required before the digital results begin to approach the ideal results.

  11. GNSS-based passive radar sensing using hybrid-aperture system

    NASA Astrophysics Data System (ADS)

    Silver, Randy; Zhang, Yan Rockee; Suarez, Hernan; Pan, Yu; Huang, Yih-Ru

    2013-05-01

    A hybrid-aperture radar system is being developed for passive, GNSS-based sensing and imaging missions. Different from previous work, the real aperture (RA) array has excellent cross-range resolution and electronic scanning capability, and synthetic aperture processing is applied for the dimension along the UAV/aircraft flight path. The hybrid aperture thus provides real-time, combined sensing capability and multiple functions. Multi-level signal synchronization and tracking is used to ensure the signal phase coherency and integrity. The advantages of covert radar sensing and reduced onboard computing complexity of this sensor are being demonstrated through experiments.

  12. Data volume reduction for imaging radar polarimetry

    NASA Technical Reports Server (NTRS)

    Zebker, Howard A. (Inventor); Held, Daniel N. (Inventor); Vanzyl, Jakob J. (Inventor); Dubois, Pascale C. (Inventor); Norikane, Lynne (Inventor)

    1988-01-01

    Two alternative methods are presented for digital reduction of synthetic aperture multipolarized radar data using scattering matrices, or using Stokes matrices, of four consecutive along-track pixels to produce averaged data for generating a synthetic polarization image.

  13. Application of synthetic aperture radar remote sensing in Antarctica

    NASA Astrophysics Data System (ADS)

    Zhou, Chunxia; Deng, Fanghui; Wan, Lei; Wang, Zemin; E, Dongchen; Zhou, Yu

    2014-05-01

    Synthetic Aperture Radar (SAR) delivers high-resolution radar images day or night, and in all weather conditions. It also offers the capability for penetrating materials. These unique capabilities boost the application of SAR remote sensing techniques in Antarctica. Based on the key area of Chinese National Antarctic Research Expedition (CHINARE) - PANDA (Prydz Bay, Amery Ice Shelf and Dome A) section, this paper summarized the typical applications of SAR data, and discussed the crevasse detection with semi-variance analysis in the SAR images of the Grove Mountains area, DEM generation with InSAR pairs and ICESat GLAS data of the Grove Mountains area and nearby areas, and ice flow velocity derivation from D-InSAR and offset tracking of the Grove Mountains area and downstream areas in East Antarctica. The studies provide important information for Antarctic fieldwork and scientific researches. It is further confirmed that Synthetic Aperture Radar remote sensing has tremendous potential in the field of glacial geomorphology, topographic mapping and glacier dynamics, etc.

  14. Synthetic aperture integration (SAI) algorithm for SAR imaging

    DOEpatents

    Chambers, David H; Mast, Jeffrey E; Paglieroni, David W; Beer, N. Reginald

    2013-07-09

    A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

  15. Spaceborne Imaging Radar Project

    NASA Technical Reports Server (NTRS)

    Herman, Neil

    1986-01-01

    In June of 1985 the Project Initiation Agreement was signed by the Jet Propulsion Laboratory and the NASA Office of Space Science and Applications for the Spaceborne Imaging Radar Project (SIR). The thrust of the Spaceborne Imaging Radar Project is to continue the evolution of synthetic aperture radar (SAR) science and technology developed during SEASAT, SIR-A and SIR-B missions to meet the needs of the Earth Observing System (EOS) in the mid 1990's. As originally formulated, the Project plans were for a reflight of the SIR-B in 1987, the development of a new SAR, SIR-C, for missions in mid 1989 and early 1990, and the upgrade of SIR-C to EOS configuration with a qualification flight aboard the shuttle in the 1993 time frame (SIR-D). However, the loss of the shuttle Challenger has delayed the first manifest for SIR to early 1990. This delay prompted the decision to drop SIR-B reflight plans and move ahead with SIR-C to more effectively utilize this first mission opportunity. The planning for this project is discussed.

  16. Automatic selection of flood water levels from high resolution Synthetic Aperture Radar images for assimilation into hydraulic models

    NASA Astrophysics Data System (ADS)

    Mason, D. C.; Schumann, G. J.-P.; Neal, J. C.; Garcia-Pintado, J.; Bates, P. D.

    2012-04-01

    Flood extents caused by fluvial floods in urban and rural areas may be predicted by hydraulic models. Assimilation may be used to correct the model state and improve the estimates of the model parameters or external forcing. One common observation assimilated is the water level at various points along the modelled reach. Distributed water levels may be estimated indirectly along the flood extents in SAR images by intersecting the extents with the floodplain DEM. It is necessary to select a subset of levels because adjacent levels along the flood extent will be strongly correlated and add little new information, while a large number of levels will increase the computational cost of the assimilation unnecessarily. The subset of points selected should be at positions at which the water level can be accurately determined, with the points distributed uniformly over the flood extent sufficiently sparsely that adjacent water levels are spatially uncorrelated. Although models run in hindcasting mode can provide useful information for predicting the effects of future floods, the ultimate goal must be to use SAR water levels in a forecasting model, which means that they have to be estimated in near real-time. A method for selecting such a subset automatically and in near real-time is described. The input to the method is a flood extent in both urban and rural areas extracted from a high resolution SAR image using an automatic near real-time algorithm based on object segmentation and classification, which takes into account, for example, object heights as well as their SAR backscatter, and the presence of radar shadow and layover in urban areas. The method of subset selection uses this flood extent to first select candidate waterline points in flooded rural areas having low slope, so that levels may be calculated accurately. The waterline levels and positions are corrected for the effects of double reflections between the water surface and emergent vegetation at the flood

  17. Simulation of synthetic aperture radar 4: Summary and recommendations

    NASA Astrophysics Data System (ADS)

    Crane, Peter M.; Bell, Herbert H.

    1990-04-01

    Four experiments were conducted to identify digital feature data base requirements for simulating synthetic aperture radar (SAR). The results indicate that lines of communication and large areal features are the principal cues used in SAR image interpretation. The results also indicate that depiction of small, individual features is required to create a simulation with acceptable realism. These small individual features may be depicted generically without adversely affecting SAR operator task performance. This approach has been proposed by the Defense Mapping Agency (DMA) as the basis for a new Digital Feature Analysis Data (DFAD) product (Level 3-C) to support high-resolution radar simulation. We recommend that the Air Force accept the proposed Level 3-C DFAD specification for SAR simulation.

  18. APQ-102 imaging radar digital image quality study

    NASA Astrophysics Data System (ADS)

    Griffin, C. R.; Estes, J. M.

    1982-11-01

    A modified APQ-102 sidelooking radar collected synthetic aperture radar (SAR) data which was digitized and recorded on wideband magnetic tape. These tapes were then ground processed into computer compatible tapes (CCT's). The CCT's may then be processed into high resolution radar images by software on the CYBER computer.

  19. APQ-102 imaging radar digital image quality study

    NASA Technical Reports Server (NTRS)

    Griffin, C. R.; Estes, J. M.

    1982-01-01

    A modified APQ-102 sidelooking radar collected synthetic aperture radar (SAR) data which was digitized and recorded on wideband magnetic tape. These tapes were then ground processed into computer compatible tapes (CCT's). The CCT's may then be processed into high resolution radar images by software on the CYBER computer.

  20. Compounding in synthetic aperture imaging.

    PubMed

    Hansen, Jens Munk; Jensen, Jørgen Arendt

    2012-09-01

    A method for obtaining compound images using synthetic aperture data is investigated using a convex array transducer. The new approach allows spatial compounding to be performed for any number of angles without reducing the frame rate or temporal resolution. This important feature is an intrinsic property of how the compound images are constructed using synthetic aperture data and an improvement compared with how spatial compounding is obtained using conventional methods. The synthetic aperture compound images are created by exploiting the linearity of delay-and-sum beamformation for data collected from multiple spherical emissions to synthesize multiple transmit and receive apertures, corresponding to imaging the tissue from multiple directions. The many images are added incoherently, to produce a single compound image. Using a 192-element, 3.5-MHz, λ-pitch transducer, it is demonstrated from tissue-phantom measurements that the speckle is reduced and the contrast resolution improved when applying synthetic aperture compound imaging. At a depth of 4 cm, the size of the synthesized apertures is optimized for lesion detection based on the speckle information density. This is a performance measure for tissue contrast resolution which quantifies the tradeoff between resolution loss and speckle reduction. The speckle information density is improved by 25% when comparing synthetic aperture compounding to a similar setup for compounding using dynamic receive focusing. The cystic resolution and clutter levels are measured using a wire phantom setup and compared with conventional application of the array, as well as to synthetic aperture imaging without compounding. If the full aperture is used for synthetic aperture compounding, the cystic resolution is improved by 41% compared with conventional imaging, and is at least as good as what can be obtained using synthetic aperture imaging without compounding. PMID:23007781

  1. Radar image analysis utilizing junctive image metamorphosis

    NASA Astrophysics Data System (ADS)

    Krueger, Peter G.; Gouge, Sally B.; Gouge, Jim O.

    1998-09-01

    A feasibility study was initiated to investigate the ability of algorithms developed for medical sonogram image analysis, to be trained for extraction of cartographic information from synthetic aperture radar imagery. BioComputer Research Inc. has applied proprietary `junctive image metamorphosis' algorithms to cancer cell recognition and identification in ultrasound prostate images. These algorithms have been shown to support automatic radar image feature detection and identification. Training set images were used to develop determinants for representative point, line and area features, which were used on test images to identify and localize the features of interest. The software is computationally conservative; operating on a PC platform in real time. The algorithms are robust; having applicability to be trained for feature recognition on any digital imagery, not just those formed from reflected energy, such as sonograms and radar images. Applications include land mass characterization, feature identification, target recognition, and change detection.

  2. Synthetic aperture radar signal processing: Trends and technologies

    NASA Technical Reports Server (NTRS)

    Curlander, John C.

    1993-01-01

    An overview of synthetic aperture radar (SAR) technology is presented in vugraph form. The following topics are covered: an SAR ground data system; SAR signal processing algorithms; SAR correlator architectures; and current and future trends.

  3. Interferometric synthetic aperture radar: building tomorrow's tools today

    USGS Publications Warehouse

    Lu, Zhong

    2006-01-01

    A synthetic aperture radar (SAR) system transmits electromagnetic (EM) waves at a wavelength that can range from a few millimeters to tens of centimeters. The radar wave propagates through the atmosphere and interacts with the Earth’s surface. Part of the energy is reflected back to the SAR system and recorded. Using a sophisticated image processing technique, called SAR processing (Curlander and McDonough, 1991), both the intensity and phase of the reflected (or backscattered) signal of each ground resolution element (a few meters to tens of meters) can be calculated in the form of a complex-valued SAR image representing the reflectivity of the ground surface. The amplitude or intensity of the SAR image is determined primarily by terrain slope, surface roughness, and dielectric constants, whereas the phase of the SAR image is determined primarily by the distance between the satellite antenna and the ground targets, slowing of the signal by the atmosphere, and the interaction of EM waves with ground surface. Interferometric SAR (InSAR) imaging, a recently developed remote sensing technique, utilizes the interaction of EM waves, referred to as interference, to measure precise distances. Very simply, InSAR involves the use of two or more SAR images of the same area to extract landscape topography and its deformation patterns.

  4. Topography estimation with interferometric synthetic aperture radar using fringe detection

    NASA Technical Reports Server (NTRS)

    Lin, Qian; Vesecky, John F.; Zebker, Howard A.

    1991-01-01

    Methods are presented for using Synthetic Aperture Radar (SAR) interferometry data to estimate surface topography. An expression is given to relate the elevation of a ground point to the phase difference of SAR images received from two spatially separated antennas. An iterative algorithm which solves for the position and elevation of each point in the image simultaneously is developed. One of the critical issues that determines the accuracy of the terrain mapping is the phase unwrapping. An approach to the problem by fringe line detection is proposed. The algorithms are tested with two Seasat SAR images of terrain near Yellowstone National Park. The resultant elevation map is compared with a USGS terrain elevation model. The error of the SAR elevation with respect to the digital terrain map is about 8.2 percent of the total terrain variation.

  5. New inverse synthetic aperture radar algorithm for translational motion compensation

    NASA Astrophysics Data System (ADS)

    Bocker, Richard P.; Henderson, Thomas B.; Jones, Scott A.; Frieden, B. R.

    1991-10-01

    Inverse synthetic aperture radar (ISAR) is an imaging technique that shows real promise in classifying airborne targets in real time under all weather conditions. Over the past few years a large body of ISAR data has been collected and considerable effort has been expended to develop algorithms to form high-resolution images from this data. One important goal of workers in this field is to develop software that will do the best job of imaging under the widest range of conditions. The success of classifying targets using ISAR is predicated upon forming highly focused radar images of these targets. Efforts to develop highly focused imaging computer software have been challenging, mainly because the imaging depends on and is affected by the motion of the target, which in general is not precisely known. Specifically, the target generally has both rotational motion about some axis and translational motion as a whole with respect to the radar. The slant-range translational motion kinematic quantities must be first accurately estimated from the data and compensated before the image can be focused. Following slant-range motion compensation, the image is further focused by determining and correcting for target rotation. The use of the burst derivative measure is proposed as a means to improve the computational efficiency of currently used ISAR algorithms. The use of this measure in motion compensation ISAR algorithms for estimating the slant-range translational motion kinematic quantities of an uncooperative target is described. Preliminary tests have been performed on simulated as well as actual ISAR data using both a Sun 4 workstation and a parallel processing transputer array. Results indicate that the burst derivative measure gives significant improvement in processing speed over the traditional entropy measure now employed.

  6. Data management approach to search and rescue synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Green, John E.; Rogers, George W.

    1997-06-01

    The NASA sponsored Search and Rescue Synthetic Aperture Radar (SAR) program seeks to use foliage penetrating synthetic aperture radar (SAR) to locate light plane crashes in remote areas. In addition to the hardware and pattern recognition issues, data management is recognized as a significant part of the overall problem. A single NASA/JPL AIRSAR polarimetric image in P, L, and C bands takes approximately 524 megabytes of storage. Algorithmic development efforts, as well as an eventual operational system, will likely require maintaining a large database of SAR imagery, as well as derived features and associated geographical information. The need for this much data is driven in large part by the complexity of the detection problem. A simple classification/detection algorithm does not currently seem feasible. Rather, a data driven approach that can incorporate local background characteristics as well as geographical information seems to be called for. This in turn makes data management a key issue. This paper presents a comprehensive data management framework suitable for the SAR problem, as well as other similar massive data set management problems.

  7. Digital Beamforming Synthetic Aperture Radar (DBSAR) Polarimetric Upgrade

    NASA Technical Reports Server (NTRS)

    Rincon, Rafael F.; Perrine, Martin; McLinden, Matthew; Valett, Susan

    2011-01-01

    The Digital Beamforming Synthetic Aperture Radar (DBSAR) is a state-of-the-art radar system developed at NASA/Goddard Space Flight Center for the development and implementation of digital beamforming radar techniques. DBSAR was recently upgraded to polarimetric operation in order to enhance its capability as a science instrument. Two polarimetric approaches were carried out which will be demonstrated in upcoming flight campaigns.

  8. Perceptual compression of magnitude-detected synthetic aperture radar imagery

    NASA Technical Reports Server (NTRS)

    Gorman, John D.; Werness, Susan A.

    1994-01-01

    A perceptually-based approach for compressing synthetic aperture radar (SAR) imagery is presented. Key components of the approach are a multiresolution wavelet transform, a bit allocation mask based on an empirical human visual system (HVS) model, and hybrid scalar/vector quantization. Specifically, wavelet shrinkage techniques are used to segregate wavelet transform coefficients into three components: local means, edges, and texture. Each of these three components is then quantized separately according to a perceptually-based bit allocation scheme. Wavelet coefficients associated with local means and edges are quantized using high-rate scalar quantization while texture information is quantized using low-rate vector quantization. The impact of the perceptually-based multiresolution compression algorithm on visual image quality, impulse response, and texture properties is assessed for fine-resolution magnitude-detected SAR imagery; excellent image quality is found at bit rates at or above 1 bpp along with graceful performance degradation at rates below 1 bpp.

  9. Optimal sampling and quantization of synthetic aperture radar signals

    NASA Technical Reports Server (NTRS)

    Wu, C.

    1978-01-01

    Some theoretical and experimental results on optimal sampling and quantization of synthetic aperture radar (SAR) signals are presented. It includes a description of a derived theoretical relationship between the pixel signal to noise ratio of processed SAR images and the number of quantization bits per sampled signal, assuming homogeneous extended targets. With this relationship known, a solution may be realized for the problem of optimal allocation of a fixed data bit-volume (for specified surface area and resolution criterion) between the number of samples and the number of bits per sample. The results indicate that to achieve the best possible image quality for a fixed bit rate and a given resolution criterion, one should quantize individual samples coarsely and thereby maximize the number of multiple looks. The theoretical results are then compared with simulation results obtained by processing aircraft SAR data.

  10. SEASAT synthetic-aperture radar data user's manual

    NASA Technical Reports Server (NTRS)

    Pravdo, S. H.; Huneycutt, B.; Holt, B. M.; Held, D. N.

    1983-01-01

    The SEASAT Synthetic-Aperture Radar (SAR) system, the data processors, the extent of the image data set, and the means by which a user obtains this data are described and the data quality is evaluated. The user is alerted to some potential problems with the existing volume of SEASAT SAR image data, and allows him to modify his use of that data accordingly. Secondly, the manual focuses on the ultimate focuses on the ultimate capabilities of the raw data set and evaluates the potential of this data for processing into accurately located, amplitude-calibrated imagery of high resolution. This allows the user to decide whether his needs require special-purpose data processing of the SAR raw data.

  11. Development of a synthetic aperture radar design approach for wide-swath implementation

    NASA Technical Reports Server (NTRS)

    Jean, B. R.

    1981-01-01

    The first phase of a study program to develop an advanced synthetic aperture radar design concept is presented. Attributes of particular importance for the system design include wide swath coverage, reduced power requirements, and versatility in the selection of frequency, polarization and incident angle. The multiple beam configuration provides imaging at a nearly constant angle of incidence and offers the potential of realizing a wide range of the attributes desired for an orbital imaging radar for Earth resources applications.

  12. Characterizing Levees using Polarimetric and Interferometric Synthetic Aperture Radar Imagery

    NASA Astrophysics Data System (ADS)

    Dabbiru, L.; Aanstoos, J. V.; Mahrooghy, M.; Gokaraju, B.; Nobrega, R. A.; Younan, N. H.

    2011-12-01

    Monitoring the physical condition of levees is vital in order to protect them from flooding. The dynamics of subsurface water events can cause damage on levee structures which could lead to slough slides, sand boils or through seepage. Synthetic Aperture Radar (SAR) technology, due to its high spatial resolution and soil penetration capability, is a good choice to identify such problem areas so that they can be treated to avoid possible catastrophic failure. The radar polarimetric and interferometric data is capable of identifying variations in soil properties of the areas which might cause levee failure. The study area encompasses portion of levees of the lower Mississippi river in the United States. The methodology of this research is mainly categorized into two streams: 1) polarimetric data analysis and classification, and 2) interferometric analysis. Two sources of SAR imagery are used: a) quad-polarized, L-band data from Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) for polarimetric classification, and b) high resolution dual-polarized Terrasar-X data for interferometric analysis. NASA's UAVSAR imagery acquired between 2009 and 2011 are used for the analysis. The polarimetric classification is performed based on the decomposition parameters: entropy (H), anisotropy (A) and alpha (α) and the results detected slough slides on the levees and potential future slides. In the interferometric approach, the Terrasar-X SAR images acquired at different times in the year 2011 are combined into pairs to exploit the phase difference of the signals. The interferometric information is used to find evidence of potential small-scale deformations which could be pre-cursors to levee failure.

  13. Synthetic aperture radar processing system for search and rescue

    NASA Astrophysics Data System (ADS)

    Huxtable, Barton D.; Jackson, Christopher R.; Mansfield, Arthur W.; Rais, Houra

    1997-06-01

    Synthetic aperture radar (SAR) is uniquely suited to help solve the search and rescue problem since it can be utilized either day or night and through both dense fog or thick cloud cover. This paper describes the search and rescue data processing system (SARDPS) developed at Goddard Space Flight Center. SARDPS was developed for the Search and Rescue Mission Office in order to conduct research, development, and technology demonstration of SAR to quickly locate small aircraft which have crashed in remote areas. In order to effectively apply SAR to the detection of crashed aircraft several technical challenges needed to be overcome. These include full resolution SAR image formation using low frequency radar appropriate for foliage penetration, the application of autofocusing for SAR motion compensation in the processing system, and the development of sophisticated candidate crash site detection algorithms. In addition, the need to dispatch rescue teams to specific locations requires precise SAR image georectification and map registration techniques. The final end-to-end processing system allows for raw SAR phase history data to be quickly converted to georeferenced map/image products with candidate crash site locations identified.

  14. Synthetic aperture radar signal processing on the MPP

    NASA Technical Reports Server (NTRS)

    Ramapriyan, H. K.; Seiler, E. J.

    1987-01-01

    Satellite-borne Synthetic Aperture Radars (SAR) sense areas of several thousand square kilometers in seconds and transmit phase history signal data several tens of megabits per second. The Shuttle Imaging Radar-B (SIR-B) has a variable swath of 20 to 50 km and acquired data over 100 kms along track in about 13 seconds. With the simplification of separability of the reference function, the processing still requires considerable resources; high speed I/O, large memory and fast computation. Processing systems with regular hardware take hours to process one Seasat image and about one hour for a SIR-B image. Bringing this processing time closer to acquisition times requires an end-to-end system solution. For the purpose of demonstration, software was implemented on the present Massively Parallel Processor (MPP) configuration for processing Seasat and SIR-B data. The software takes advantage of the high processing speed offered by the MPP, the large Staging Buffer, and the high speed I/O between the MPP array unit and the Staging Buffer. It was found that with unoptimized Parallel Pascal code, the processing time on the MPP for a 4096 x 4096 sample subset of signal data ranges between 18 and 30.2 seconds depending on options.

  15. Fourier-domain multichannel autofocus for synthetic aperture radar.

    PubMed

    Liu, Kuang-Hung; Munson, David C

    2011-12-01

    Synthetic aperture radar (SAR) imaging suffers from image focus degradation in the presence of phase errors in the received signal due to unknown platform motion or signal propagation delays. We present a new autofocus algorithm, termed Fourier-domain multichannel autofocus (FMCA), that is derived under a linear algebraic framework, allowing the SAR image to be focused in a noniterative fashion. Motivated by the mutichannel autofocus (MCA) approach, the proposed autofocus algorithm invokes the assumption of a low-return region, which generally is provided within the antenna sidelobes. Unlike MCA, FMCA works with the collected polar Fourier data directly and is capable of accommodating wide-angle monostatic SAR and bistatic SAR scenarios. Most previous SAR autofocus algorithms rely on the prior assumption that radar's range of look angles is small so that the phase errors can be modeled as varying along only one dimension in the collected Fourier data. And, in some cases, implicit assumptions are made regarding the SAR scene. Performance of such autofocus algorithms degrades if the assumptions are not satisfied. The proposed algorithm has the advantage that it does not require prior assumptions about the range of look angles, nor characteristics of the scene. PMID:21606028

  16. Computing Ocean Surface Currents from Satellite Synthetic Aperture Radar Imagery

    NASA Astrophysics Data System (ADS)

    Qazi, Waqas A.

    Ocean surface currents play an important role in ocean-atmosphere interactions and global ocean circulation, and are also significant for fishing, ocean navigation, and search & rescue. Existing in-situ and remote sensing techniques for measuring ocean surface currents are limited by spatial and temporal data coverage, and thermal IR feature tracking methods are limited by clouds and weak thermal gradients. High-resolution spaceborne Synthetic Aperture Radar (SAR) offers repeatable cloud-penetrating measurements of the ocean surface. This research explores methods for ocean surface current measurement through satellite-based SAR. The major part of this research is concerned with the development and application of a semi-automated algorithm to generate ocean surface currents at ˜1.9 km resolution from sequential spaceborne C-band SAR intensity images using the Maximum Cross-Correlation(MCC) method. The primary geographical area of study is the coastal California Current System (CCS), and nearly two years (2008-2009) of 30-min lag data from the Envisat ASAR and ERS-2 AMI SAR sensors is analyzed. The velocity wavenumber spectrum of the derived MCC SAR currents agrees with the k-2 power law as predicted by submesoscale resolution models, and also shows seasonal mesoscale variability. The derived MCC SAR currents are validated against High frequency (HF) radar currents, and the two show some agreement in vector direction, with MCC SAR vectors oriented slightly anti-clockwise relative to HF radar vectors. The unimodal mean-symmetric residual histograms indicate that errors between the two datasets are random, except for a mean positive bias of ≈ 11 cm/s in MCC SAR currents relative to HF radar currents. This magnitude difference occurs primarily in the along-shore component ( ≈ 6 cm/s) and is negligible in the cross-shore component. Doppler Centroid Cross-Track (XT) radial currents from Envisat Wide Swath Mode (WSM) scenes are compared with HF radar radial currents

  17. The DESDynI Synthetic Aperture Radar Array-Fed Reflector Antenna

    NASA Technical Reports Server (NTRS)

    Chamberlain, Neil; Ghaemi, Hirad; Giersch, Louis; Harcke, Leif; Hodges, Richard; Hoffman, James; Johnson, William; Jordan, Rolando; Khayatian, Behrouz; Rosen, Paul; Sadowy, Gregory; Shaffer, Scott; Shen, Yuhsyen; Veilleux, Louise; Wu, Patrick

    2010-01-01

    DESDynI is a mission being developed by NASA with radar and lidar instruments for Earth-orbit remote sensing. This paper focuses on the design of a largeaperture antenna for the radar instrument. The antenna comprises a deployable reflector antenna and an active switched array of patch elements fed by transmit/ receive modules. The antenna and radar architecture facilitates a new mode of synthetic aperture radar imaging called 'SweepSAR'. A system-level description of the antenna is provided, along with predictions of antenna performance.

  18. Use of Synthetic Aperture Radar in Cold Climate Flood Response

    NASA Astrophysics Data System (ADS)

    Yarbrough, L. D.

    2009-12-01

    The purpose of this study was to investigate the usefulness of Synthetic Aperture Radar (SAR) satellite images during a cold climate disaster response event. There were 15 European Space Agency (ESA) Advanced Synthetic Aperture Radar ASAR scenes, five Japan Aerospace Exploration Agency (JAXA) Phased Array type L-band Synthetic Aperture Radar (PALSAR) scenes, one RADARSAT2 scene, and numerous optical sensor data. These data were primarily used to indentify floodwater inundation polygons and flow vectors. However, in cold climate flooding, there are complicating factors such as frazil ice, ice jams, and snow-covered, frozen flood waters that are not present during warmer flooding events. The imagery was obtained through the International Charter "Space and Major Disasters.” The Charter aims at providing a unified system of space data acquisition and delivery to those affected by natural or man-made disasters through Authorized Users. Each member agency has committed resources to support the provisions of the Charter, and thus is helping to mitigate the effects of disasters on human life and property. On 25 March 2009, the Charter was activated in response to the flooding along the Red River of the North in the states of North Dakota and Minnesota of the United States. The delivery time of a single SAR scene from a Charter participant was less than 12 hours from the time of acquisition. This expedited service allowed additional time for creating image-based derivations, field checking and delivery to a decision maker or emergency responder. SAR-derived data sets include identification of river ice and saturated ground conditions. This data could be provided to experts in river ice engineering for use in the development of plans to reduce ice jamming, its effect on water levels and additional stresses on river infrastructure. During disaster response applications, SAR data was found to very useful in indentifying open water and the front of ice jams. Using a river

  19. Temporal Stability of Soil Moisture and Radar Backscatter Observed by the Advanced Synthetic Aperture Radar (ASAR)

    PubMed Central

    Wagner, Wolfgang; Pathe, Carsten; Doubkova, Marcela; Sabel, Daniel; Bartsch, Annett; Hasenauer, Stefan; Blöschl, Günter; Scipal, Klaus; Martínez-Fernández, José; Löw, Alexander

    2008-01-01

    The high spatio-temporal variability of soil moisture is the result of atmospheric forcing and redistribution processes related to terrain, soil, and vegetation characteristics. Despite this high variability, many field studies have shown that in the temporal domain soil moisture measured at specific locations is correlated to the mean soil moisture content over an area. Since the measurements taken by Synthetic Aperture Radar (SAR) instruments are very sensitive to soil moisture it is hypothesized that the temporally stable soil moisture patterns are reflected in the radar backscatter measurements. To verify this hypothesis 73 Wide Swath (WS) images have been acquired by the ENVISAT Advanced Synthetic Aperture Radar (ASAR) over the REMEDHUS soil moisture network located in the Duero basin, Spain. It is found that a time-invariant linear relationship is well suited for relating local scale (pixel) and regional scale (50 km) backscatter. The observed linear model coefficients can be estimated by considering the scattering properties of the terrain and vegetation and the soil moisture scaling properties. For both linear model coefficients, the relative error between observed and modelled values is less than 5 % and the coefficient of determination (R2) is 86 %. The results are of relevance for interpreting and downscaling coarse resolution soil moisture data retrieved from active (METOP ASCAT) and passive (SMOS, AMSR-E) instruments.

  20. Application of microprocessors to spacecraft synthetic aperture radar processing

    NASA Technical Reports Server (NTRS)

    Arens, W. E.

    1978-01-01

    A ground-based digital synthetic aperture radar (SAR) processor capable of correlating images from raw spacecraft data at real-time rates is currently under development. The processor design requirements are particularly formidable due to (1) range migration effects resulting from planetary curvature and rotation, (2) antenna beam pointing errors, and (3) variation of the Doppler reference function with changing orbital parameters. Based upon the current effort, this paper describes a candidate real-time on-board SAR processing implementation approach that might evolve for future spacecraft applications. Key features include the use of custom large scale integration (LSI) charge-coupled device (CCD) technology to accomplish the correlation functions and microprocessor technology to effect control.

  1. New formulation for interferometric synthetic aperture radar for terrain mapping

    SciTech Connect

    Jakowatz, C.V. Jr.; Wahl, D.E.; Eichel, P.H.; Thompson, P.A.

    1994-04-01

    The subject of interferometric synthetic aperture radar (IFSAR) for high-accuracy terrain elevation mapping continues to gain importance in the arena of radar signal processing. Applications to problems in precision terrain-aided guidance and automatic target recognition, as well as a variety of civil applications, are being studied by a number of researchers. Not unlike many other areas of SAR processing, the subject of IFSAR can at first glance appear to be somewhat mysterious. In this paper we show how the mathematics of IFSAR for terrain elevation mapping using a pair of spotlight mode SAR collections can be derived in a very straightforward manner. Here, we employ an approach that relies entirely on three-dimensional Fourier transforms, and utilizes no reference to range equations or Doppler concepts. The result is a simplified explanation of the fundamentals of interferometry, including an easily-seen link between image domain phase difference and terrain elevation height. The derivation builds upon previous work by the authors in which a framework for spotlight mode SAR image formation based on an analogy to three-dimensional computerized axial tomography (CAT) was developed. After outlining the major steps in the mathematics, we show how a computer simulator which utilizes three-dimensional Fourier transforms can be constructed that demonstrates all of the major aspects of IFSAR from spotlight mode collections.

  2. Augmenting synthetic aperture radar with space time adaptive processing

    NASA Astrophysics Data System (ADS)

    Riedl, Michael; Potter, Lee C.; Ertin, Emre

    2013-05-01

    Wide-area persistent radar video offers the ability to track moving targets. A shortcoming of the current technology is an inability to maintain track when Doppler shift places moving target returns co-located with strong clutter. Further, the high down-link data rate required for wide-area imaging presents a stringent system bottleneck. We present a multi-channel approach to augment the synthetic aperture radar (SAR) modality with space time adaptive processing (STAP) while constraining the down-link data rate to that of a single antenna SAR system. To this end, we adopt a multiple transmit, single receive (MISO) architecture. A frequency division design for orthogonal transmit waveforms is presented; the approach maintains coherence on clutter, achieves the maximal unaliased band of radial velocities, retains full resolution SAR images, and requires no increase in receiver data rate vis-a-vis the wide-area SAR modality. For Nt transmit antennas and N samples per pulse, the enhanced sensing provides a STAP capability with Nt times larger range bins than the SAR mode, at the cost of O(log N) more computations per pulse. The proposed MISO system and the associated signal processing are detailed, and the approach is numerically demonstrated via simulation of an airborne X-band system.

  3. Integration of optical and synthetic aperture radar (SAR) images to differentiate grassland and alfalfa in Prairie area

    NASA Astrophysics Data System (ADS)

    Hong, Gang; Zhang, Aining; Zhou, Fuqun; Brisco, Brian

    2014-05-01

    Alfalfa presents a huge potential biofuel source in the Prairie Provinces of Canada. However, it remains a challenge to find an ideal single satellite sensor to monitor the regional spatial distribution of alfalfa on an annual basis. The primary interest of this study is to identify alfalfa spatial distribution through effectively differentiating alfalfa from grasslands, given their spectral similarity and same growth calendars. MODIS and RADARSAT-2 ScanSAR narrow mode were selected for regional-level grassland and alfalfa differentiation in the Prairie Provinces, due to the high frequency revisit of MODIS, the weather independence of ScanSAR as well as the large area coverage and the complementary characteristics SAR and optical images. Combining MODIS and ScanSAR in differentiating alfalfa and grassland is very challenging, since there is a large spatial resolution difference between MODIS (250 m) and ScanSAR narrow (50 m). This study investigated an innovative image fusion technique for combining MODIS and ScanSAR and obtaining a synthetic image which has the high spatial details derived from ScanSAR and the colour information from MODIS. The field trip was arranged to collect ground truth to label and validate the classification results. The fusion classification result shows significant accuracy improvement when compared with either ScanSAR or MODIS alone or with other commonly-used data combination methods, such as multiple files composites. This study has shown that the image fusion technique used in this study can combine the structural information from high resolution ScanSAR and colour information from MODIS to significantly improve the classification accuracy between alfalfa and grassland.

  4. Space Radar Image of Baikal Lake, Russia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is an X-band black-and-white image of the forests east of the Baikal Forest in the Jablonowy Mountains of Russia. The image is centered at 52.5 degrees north latitude and 116 degrees east longitude near the mining town of Bukatschatscha. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar aboard the space shuttle Endeavour on October 4, 1994, during the second flight of the spaceborne radar. This area is part of an international research project known as the Taiga Aerospace Investigation using Geographic Information System Applications.

  5. Metamaterial Apertures for Computational Imaging

    NASA Astrophysics Data System (ADS)

    Hunt, John; Driscoll, Tom; Mrozack, Alex; Lipworth, Guy; Reynolds, Matthew; Brady, David; Smith, David R.

    2013-01-01

    By leveraging metamaterials and compressive imaging, a low-profile aperture capable of microwave imaging without lenses, moving parts, or phase shifters is demonstrated. This designer aperture allows image compression to be performed on the physical hardware layer rather than in the postprocessing stage, thus averting the detector, storage, and transmission costs associated with full diffraction-limited sampling of a scene. A guided-wave metamaterial aperture is used to perform compressive image reconstruction at 10 frames per second of two-dimensional (range and angle) sparse still and video scenes at K-band (18 to 26 gigahertz) frequencies, using frequency diversity to avoid mechanical scanning. Image acquisition is accomplished with a 40:1 compression ratio.

  6. Servomechanism for Doppler shift compensation in optical correlator for synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Constaninides, N. J.; Bicknell, T. J. (Inventor)

    1980-01-01

    A method and apparatus for correcting Doppler shifts in synthetic aperture radar data is described. An optical correlator for synthetic aperture radar data has a means for directing a laser beam at a signal film having radar return pulse intensity information recorded on it. A resultant laser beam passes through a range telescope, an azimuth telescope, and a Fourier transform filter located between the range and azimuth telescopes, and forms an image for recording on an image film. A compensation means for Doppler shift in the radar return pulse intensity information includes a beam splitter for reflecting the modulated laser beam, after having passed through the Fourier transform filter, to a detection screen having two photodiodes mounted on it.

  7. Synthetic aperture radar observation of ocean roughness from rolls in an unstable marine boundary layer

    NASA Technical Reports Server (NTRS)

    Thompson, T. W.; Liu, W. T.; Weissman, D. E.

    1983-01-01

    Simultaneous synthetic aperture radar (SAR) and cloud photographic observations of the Atlantic Ocean off the coast of Florida were made from a high-altitude aircraft when there was an unstable marine boundary layer. The synthetic aperture radar images show unusual kilometer-sized features on the ocean surface which are related to clouds. The ocean near shore was cloud-free and had no radar features, while from 30 to 330 km offshore there were clouds and prominent kilometer-sized features in the SAR image. These radar features are most prominent when the radar was looking upwind, are less prominent when the radar was looking downwind, and disappear entirely when the radar was looking crosswind. Since ocean radar echo strengths are believed to be controlled primarily by ocean waves satisfying the Bragg relation, these radar features most likely resulted from local enhancements of short gravity waves with 17- to 34-cm wavelengths, which in turn are surface expressions of roll convections in a kilometer-thick unstable marine boundary layer.

  8. The US open skies synthetic aperture radar (SAROS)

    SciTech Connect

    Fortner, K.R.; Hezeltine, P.L.

    1996-11-01

    This paper discusses the Synthetic Aperture Radar for Open Skies (SAROS), an airborne side-looking synthetic aperture radar (SAR) system installed on the U.S. OC-135B Open Skies Observation Aircraft. The paper discusses in detail how the SAROS is designed to meet the performance requirements and limits of the Treaty on Open Skies. The SAROS is based on the U.S. AN/APD-12 analog radar system which has been modified to digitally record radar, motion, and annotation data on magnetic tape and has been designated as the AN/APD-14. The theoretical performance of the AN/APD-12 SAR exceeds the three meter range and azimuth resolution allowed by the Treaty. The SAROS design will limit the performance of the SAR to no better than three meter`s through reduction in transmitted frequency bandwidth, reduction in azimuth bandwidth, and decimation of azimuth sampling prior to recording of the phase history data. 5 figs.

  9. Synthetic aperture radar system design for random field classification

    NASA Technical Reports Server (NTRS)

    Harger, R. O.

    1973-01-01

    An optimum design study is carried out for synthetic aperture radar systems intended for classifying randomly reflecting areas (such as agricultural fields) characterized by a reflectivity density spectral density. The problem solution is obtained, neglecting interfield interference and assuming areas of known configuration and location, as well as a certain Gaussian signal field property. The optimum processor is nonlinear, but includes conventional matched filter processing. A set of summary design curves is plotted, and is applied to the design of a satellite synthetic aperture radar system.

  10. The NASA Airborne Synthetic Aperture Radar System

    NASA Technical Reports Server (NTRS)

    Lou, Yunling; Kim, Yunjin; van Zyl, Jakob

    1996-01-01

    None given. (From introduction): ...we will briefly describe the instrument characteristics, the evolution of the various radar modes, the instrument performance and improvement in the knowledge of the positioning and attitude information of the radar. In addition, we will summarize the [rogress of the data processing effort, especially in the interferometry processing. Finally, we will address the issue of processing and calibrating the cross-track interferometry (XTI) data.

  11. A global search and rescue concept using synthetic aperture radar and passive user targets

    NASA Technical Reports Server (NTRS)

    Sivertson, W. E., Jr.

    1976-01-01

    A terrestrial search and rescue concept is defined embodying the use of passive radio-frequency reflectors in conjunction with an orbiting synthetic aperture radar to detect, identify, and locate users. An airborne radar test was conducted to evaluate the basic concept. In this test simple corner-reflector targets were successfully imaged. Results from this investigation were positive and indicate that the concept can be used to investigate new approaches focused on the development of a global search and rescue system.

  12. Detection of built-up area in optical and synthetic aperture radar images using conditional random fields

    NASA Astrophysics Data System (ADS)

    Kenduiywo, Benson Kipkemboi; Tolpekin, Valentyn A.; Stein, Alfred

    2014-01-01

    Classifying built-up areas from satellite images is a challenging task due to spatial and spectral heterogeneity of the classes. In this study, a contextual classification method based on conditional random fields (CRFs) has been used. Spatial and spectral information from blocks of pixels were employed to identify built-up areas. The CRF association potential was based on support vector machines (SVMs), whereas the CRF interaction potential included a data-dependent term using the inverse of the transformed Euclidean distance. In this way, accuracy was stable for a varying smoothness parameter, while preserving class boundaries and aggregating similar labels, and a discontinuity adaptive model was obtained and conditioned on data evidence. The classification was applied on satellite towns around the city of Nairobi, Kenya. The accuracy exceeded that of Markov random fields, SVM, and maximum likelihood classification by 1.13%, 2.22%, and 8.23%, respectively. The CRF method had the lowest fraction of false positives. The study concluded that CRFs can be used to better detect built-up areas. In this way, it provides accurate timely spatial information to urban planners and other professionals.

  13. Spaceborne Imaging Radar-C instrument

    NASA Technical Reports Server (NTRS)

    Huneycutt, Bryan L.

    1993-01-01

    The Spaceborne Imaging Radar-C is the next radar in the series of spaceborne radar experiments, which began with Seasat and continued with SIR-A and SIR-B. The SIR-C instrument has been designed to obtain simultaneous multifrequency and simultaneous multipolarization radar images from a low earth orbit. It is a multiparameter imaging radar that will be flown during at least two different seasons. The instrument operates in the squint alignment mode, the extended aperture mode, the scansar mode, and the interferometry mode. The instrument uses engineering techniques such as beam nulling for echo tracking, pulse repetition frequency hopping for Doppler centroid tracking, generating the frequency step chirp for radar parameter flexibility, block floating-point quantizing for data rate compression, and elevation beamwidth broadening for increasing the swath illumination.

  14. Radar Image of Galapagos Island

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is an image showing part of Isla Isabella in the western Galapagos Islands. It was taken by the L-band radar in HH polarization from the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar on the 40th orbit of the space shuttle Endeavour. The image is centered at about 0.5 degree south latitude and 91 degrees west longitude and covers an area of 75 by 60 kilometers (47 by 37 miles). The radar incidence angle at the center of the image is about 20 degrees.

    The western Galapagos Islands, which lie about 1,200 kilometers (750 miles) west of Ecuador in the eastern Pacific, have six active volcanoes similar to the volcanoes found in Hawaii. Since the time of Charles Darwin's visit to the area in 1835, there have been over 60 recorded eruptions of these volcanoes. This SIR-C/X-SAR image of Alcedo and Sierra Negra volcanoes shows the rougher lava flows as bright features, while ash deposits and smooth pahoehoe lava flows appear dark. A small portion of Isla Fernandina is visible in the extreme upper left corner of the image.

    The Galapagos Islands are one of the SIR-C/X-SAR supersites and data of this area will be taken several times during the flight to allow scientists to conduct topographic change studies and to search for different lava flow types, ash deposits and fault lines.

    Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes

  15. The potential of flood forecasting using a variable-resolution global Digital Terrain Model and flood extents from Synthetic Aperture Radar images.

    NASA Astrophysics Data System (ADS)

    Mason, David; Garcia-Pintado, Javier; Cloke, Hannah; Dance, Sarah

    2015-08-01

    A basic data requirement of a river flood inundation model is a Digital Terrain Model (DTM) of the reach being studied. The scale at which modeling is required determines the accuracy required of the DTM. For modeling floods in urban areas, a high resolution DTM such as that produced by airborne LiDAR (Light Detection And Ranging) is most useful, and large parts of many developed countries have now been mapped using LiDAR. In remoter areas, it is possible to model flooding on a larger scale using a lower resolution DTM, and in the near future the DTM of choice is likely to be that derived from the TanDEM-X Digital Elevation Model (DEM). A variable-resolution global DTM obtained by combining existing high and low resolution data sets would be useful for modeling flood water dynamics globally, at high resolution wherever possible and at lower resolution over larger rivers in remote areas. A further important data resource used in flood modeling is the flood extent, commonly derived from Synthetic Aperture Radar (SAR) images. Flood extents become more useful if they are intersected with the DTM, when water level observations (WLOs) at the flood boundary can be estimated at various points along the river reach. To illustrate the utility of such a global DTM, two examples of recent research involving WLOs at opposite ends of the spatial scale are discussed. The first requires high resolution spatial data, and involves the assimilation of WLOs from a real sequence of high resolution SAR images into a flood model to update the model state with observations over time, and to estimate river discharge and model parameters, including river bathymetry and friction. The results indicate the feasibility of such an Earth Observation-based flood forecasting system. The second example is at a larger scale, and uses SAR-derived WLOs to improve the lower-resolution TanDEM-X DEM in the area covered by the flood extents. The resulting reduction in random height error is significant.

  16. Micropower impulse radar imaging

    SciTech Connect

    Hall, M.S.

    1995-11-01

    From designs developed at the Lawrence Livermore National Laboratory (LLNL) in radar and imaging technologies, there exists the potential for a variety of applications in both public and private sectors. Presently tests are being conducted for the detection of buried mines and the analysis of civil structures. These new systems use a patented ultra-wide band (impulse) radar technology known as Micropower Impulse Radar (GPR) imaging systems. LLNL has also developed signal processing software capable of producing 2-D and 3-D images of objects embedded in materials such as soil, wood and concrete. My assignment while at LLNL has focused on the testing of different radar configurations and applications, as well as assisting in the creation of computer algorithms which enable the radar to scan target areas of different geometeries.

  17. Antenna dimensions of synthetic aperture radar systems on satellites

    NASA Technical Reports Server (NTRS)

    Richter, K. R.

    1973-01-01

    Design of a synthetic aperture radar (SAR) for a satellite must take into account the limitation in weight and dimensions of the antenna. The lower limits of the antenna area are derived from the conditions of unambiguity of the SAR system. This result is applied to estimate the antenna requirements for SARs on satellites in circular orbits of various altitudes around Earth and Venus.

  18. Eliminating Doppler Effects in Synthetic-Aperture Radar Optical Processors

    NASA Technical Reports Server (NTRS)

    Constantindes, N. J.; Bicknell, T. J.

    1984-01-01

    Pair of photodetectors generates correction signals. Instrument detects Doppler shifts in radar and corrects processing parameters so ambiguities caused by shifts not manifested as double or overlapping images.

  19. Lucky imaging and aperture synthesis with low-redundancy apertures.

    PubMed

    Ward, Jennifer E; Rhodes, William T; Sheridan, John T

    2009-01-01

    Lucky imaging, used with some success in astronomical and even horizontal-path imaging, relies on fleeting conditions of the atmosphere that allow momentary improvements in image quality, at least in portions of an image. Aperture synthesis allows a larger aperture and, thus, a higher-resolution imaging system to be synthesized through the superposition of image spatial-frequency components gathered by cooperative combinations of smaller subapertures. A combination of lucky imaging and aperture synthesis strengthens both methods for obtaining improved images through the turbulent atmosphere. We realize the lucky imaging condition appropriate for aperture synthesis imaging for a pair of rectangular subapertures and demonstrate that this condition occurs when the signal energy associated with bandpass spatial-frequency components achieves its maximum value. PMID:19107157

  20. Lynx: A High-Resolution Synthetic Aperture Radar

    SciTech Connect

    Doerry, A.W.; Hensley, W.H.; Pace, F.; Stence, J.; Tsunoda, S.I.; Walker, B.C.; Woodring, M.

    1999-03-08

    Lynx is a high resolution, synthetic aperture radar (SAR) that has been designed and built by Sandia National Laboratories in collaboration with General Atomics (GA). Although Lynx may be operated on a wide variety of manned and unmanned platforms, it is primarily intended to be fielded on unmanned aerial vehicles. In particular, it may be operated on the Predator, I-GNAT, or Prowler II platforms manufactured by GA Aeronautical Systems, Inc. The Lynx production weight is less than 120 lb. and has a slant range of 30 km (in 4 mm/hr rain). It has operator selectable resolution and is capable of 0.1 m resolution in spotlight mode and 0.3 m resolution in stripmap mode. In ground moving target indicator mode, the minimum detectable velocity is 6 knots with a minimum target cross-section of 10 dBsm. In coherent change detection mode, Lynx makes registered, complex image comparisons either of 0.1 m resolution (minimum) spotlight images or of 0.3 m resolution (minimum) strip images. The Lynx user interface features a view manager that allows it to pan and zoom like a video camera. Lynx was developed under corporate finding from GA and will be manufactured by GA for both military and commercial applications. The Lynx system architecture will be presented and some of its unique features will be described. Imagery at the finest resolutions in both spotlight and strip modes have been obtained and will also be presented.

  1. Natural and Unnatural Oil Layers on the Surface of the Gulf of Mexico Detected and Quantified in Synthetic Aperture RADAR Images with Texture Classifying Neural Network Algorithms

    NASA Astrophysics Data System (ADS)

    MacDonald, I. R.; Garcia-Pineda, O. G.; Morey, S. L.; Huffer, F.

    2011-12-01

    Effervescent hydrocarbons rise naturally from hydrocarbon seeps in the Gulf of Mexico and reach the ocean surface. This oil forms thin (~0.1 μm) layers that enhance specular reflectivity and have been widely used to quantify the abundance and distribution of natural seeps using synthetic aperture radar (SAR). An analogous process occurred at a vastly greater scale for oil and gas discharged from BP's Macondo well blowout. SAR data allow direct comparison of the areas of the ocean surface covered by oil from natural sources and the discharge. We used a texture classifying neural network algorithm to quantify the areas of naturally occurring oil-covered water in 176 SAR image collections from the Gulf of Mexico obtained between May 1997 and November 2007, prior to the blowout. Separately we also analyzed 36 SAR images collections obtained between 26 April and 30 July, 2010 while the discharged oil was visible in the Gulf of Mexico. For the naturally occurring oil, we removed pollution events and transient oceanographic effects by including only the reflectance anomalies that that recurred in the same locality over multiple images. We measured the area of oil layers in a grid of 10x10 km cells covering the entire Gulf of Mexico. Floating oil layers were observed in only a fraction of the total Gulf area amounting to 1.22x10^5 km^2. In a bootstrap sample of 2000 replications, the combined average area of these layers was 7.80x10^2 km^2 (sd 86.03). For a regional comparison, we divided the Gulf of Mexico into four quadrates along 90° W longitude, and 25° N latitude. The NE quadrate, where the BP discharge occurred, received on average 7.0% of the total natural seepage in the Gulf of Mexico (5.24 x10^2 km^2, sd 21.99); the NW quadrate received on average 68.0% of this total (5.30 x10^2 km^2, sd 69.67). The BP blowout occurred in the NE quadrate of the Gulf of Mexico; discharged oil that reached the surface drifted over a large area north of 25° N. Performing a

  2. Multiple aperture imager component development

    NASA Astrophysics Data System (ADS)

    Lees, David E.; Henshaw, Philip D.

    1991-03-01

    This final report presents results of an experimental and analytical effort to develop multiple aperture imagers built from unphased, direct-detection subapertures. An object was imaged using wave length shift instead of object motion to create multiple speckle pattern realizations. An analysis of subaperture geometry effects of autocorrelation estimate was performed. Experimental measurements of detector modulator transfer function were made. Finally, a new algorithm to reconstruct imagery with improved signal-to-noise ratio was developed.

  3. Feasibility of Using Synthetic Aperture Radar to Aid UAV Navigation.

    PubMed

    Nitti, Davide O; Bovenga, Fabio; Chiaradia, Maria T; Greco, Mario; Pinelli, Gianpaolo

    2015-01-01

    This study explores the potential of Synthetic Aperture Radar (SAR) to aid Unmanned Aerial Vehicle (UAV) navigation when Inertial Navigation System (INS) measurements are not accurate enough to eliminate drifts from a planned trajectory. This problem can affect medium-altitude long-endurance (MALE) UAV class, which permits heavy and wide payloads (as required by SAR) and flights for thousands of kilometres accumulating large drifts. The basic idea is to infer position and attitude of an aerial platform by inspecting both amplitude and phase of SAR images acquired onboard. For the amplitude-based approach, the system navigation corrections are obtained by matching the actual coordinates of ground landmarks with those automatically extracted from the SAR image. When the use of SAR amplitude is unfeasible, the phase content can be exploited through SAR interferometry by using a reference Digital Terrain Model (DTM). A feasibility analysis was carried out to derive system requirements by exploring both radiometric and geometric parameters of the acquisition setting. We showed that MALE UAV, specific commercial navigation sensors and SAR systems, typical landmark position accuracy and classes, and available DTMs lead to estimated UAV coordinates with errors bounded within ±12 m, thus making feasible the proposed SAR-based backup system. PMID:26225977

  4. Quantitative statistical assessment of conditional models for synthetic aperture radar.

    PubMed

    DeVore, Michael D; O'Sullivan, Joseph A

    2004-02-01

    Many applications of object recognition in the presence of pose uncertainty rely on statistical models-conditioned on pose-for observations. The image statistics of three-dimensional (3-D) objects are often assumed to belong to a family of distributions with unknown model parameters that vary with one or more continuous-valued pose parameters. Many methods for statistical model assessment, for example the tests of Kolmogorov-Smirnov and K. Pearson, require that all model parameters be fully specified or that sample sizes be large. Assessing pose-dependent models from a finite number of observations over a variety of poses can violate these requirements. However, a large number of small samples, corresponding to unique combinations of object, pose, and pixel location, are often available. We develop methods for model testing which assume a large number of small samples and apply them to the comparison of three models for synthetic aperture radar images of 3-D objects with varying pose. Each model is directly related to the Gaussian distribution and is assessed both in terms of goodness-of-fit and underlying model assumptions, such as independence, known mean, and homoscedasticity. Test results are presented in terms of the functional relationship between a given significance level and the percentage of samples that wold fail a test at that level. PMID:15376934

  5. Feasibility of Using Synthetic Aperture Radar to Aid UAV Navigation

    PubMed Central

    Nitti, Davide O.; Bovenga, Fabio; Chiaradia, Maria T.; Greco, Mario; Pinelli, Gianpaolo

    2015-01-01

    This study explores the potential of Synthetic Aperture Radar (SAR) to aid Unmanned Aerial Vehicle (UAV) navigation when Inertial Navigation System (INS) measurements are not accurate enough to eliminate drifts from a planned trajectory. This problem can affect medium-altitude long-endurance (MALE) UAV class, which permits heavy and wide payloads (as required by SAR) and flights for thousands of kilometres accumulating large drifts. The basic idea is to infer position and attitude of an aerial platform by inspecting both amplitude and phase of SAR images acquired onboard. For the amplitude-based approach, the system navigation corrections are obtained by matching the actual coordinates of ground landmarks with those automatically extracted from the SAR image. When the use of SAR amplitude is unfeasible, the phase content can be exploited through SAR interferometry by using a reference Digital Terrain Model (DTM). A feasibility analysis was carried out to derive system requirements by exploring both radiometric and geometric parameters of the acquisition setting. We showed that MALE UAV, specific commercial navigation sensors and SAR systems, typical landmark position accuracy and classes, and available DTMs lead to estimate UAV coordinates with errors bounded within ±12 m, thus making feasible the proposed SAR-based backup system. PMID:26225977

  6. Spaceborne synthetic aperture radar pilot study

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A pilot study of a spaceborne sidelooking radar is summarized. The results of the system trade studies are given along with the electrical parameters for the proposed subsystems. The mechanical aspects, packaging, thermal control and dynamics of the proposed design are presented. Details of the data processor are given. A system is described that allows the data from a pass over the U. S. to be in hard copy form within two hours. Also included are the proposed schedule, work breakdown structure, and cost estimate.

  7. Analysis coherent signal processing methods in synthetic aperture radar on small-scale viewing angles under voluntary movement aircraft

    NASA Astrophysics Data System (ADS)

    Anikin, Sergey N.; Vishentsev, Mihail V.; Stukalova, Anna S.

    2007-02-01

    In the article realize analysis the coherent processing method which uses to form synthetic aperture antenna on a board of aircraft. The factors, which send for distortion radar image on small-scale viewing angle during high-intensity maneuvering velocity shown for considering method of synthesizing aperture antenna. A synthetic aperture antenna software model was designing and analyzing. Some results of research of the coherent processing methods for receiving earth's imagery are shown.

  8. Autonomous system for initializing synthetic aperture radar seeker acquisition

    SciTech Connect

    Hamilton, P.C.

    1993-08-03

    A method is described of guiding a missile having an active seeker including a synthetic aperture radar operating in a squint mode to a target aircraft having a search radar therein the maximum range of active seeker acquisition being within said missile's maneuver capability to intercept, and the maximum range of active seeker acquisition not exceeding the capability of the active seeker, said method comprising the steps of: launching said missile in response to detection of the search radar; implementing a passive seeker mode of operation to passively guide said missile towards said target aircraft in a manner to avoid detection of said missile by said target aircraft; transferring from said passive seeker mode to an active seeker mode in response to detected shutdown of said search radar; maneuvering said missile to execute a turn angle away from said target aircraft such that the search field of said synthetic aperture radar sweeps through an entire target uncertainty volume, said turn angle being within a first preselected limit and a second preselected limit such that said target aircraft does not cross over said missile's terminal flight path; and intercepting said target aircraft within a lethal range of said missile.

  9. Proceedings of the Third Airborne Synthetic Aperture Radar (AIRSAR) Workshop

    NASA Technical Reports Server (NTRS)

    Vanzyl, Jakob J. (Editor)

    1991-01-01

    The Third Airborne Synthetic Aperture Radar (AIRSAR) Workshop was held on 23-24 May 1991 at JPL. Thirty oral presentations were made and 18 poster papers displayed during the workshop. Papers from these 25 presentations are presented which include analyses of AIRSAR operations and studies in SAR remote sensing, ecology, hydrology, soil science, geology, oceanography, volcanology, and SAR mapping and data handling. Results from these studies indicate the direction and emphasis of future orbital radar-sensor missions that will be launched during the 1990's.

  10. The NASA/JPL Airborne Synthetic Aperture Radar System

    NASA Technical Reports Server (NTRS)

    Lou, Yunling; Kim,Yunjin; vanZyl, Jakob

    1996-01-01

    In this paper we will briefly describe the instrument characteristics, the evolution of various radar modes, the instrument performance and improvement in the knowledge of the positioning and attitude information of the NASA/JPL airborne synthetic aperture radar (SAR). This system operates in the fully polarimetric mode in the P, L, and C band simultaneously or in the interferometric mode in both the L and C band simultaneously. We also summarize the progress of the data processing effort, especially in the interferometry processing and we address the issue of processing and calibrating the cross-track interferometry data.

  11. Waveform error analysis for bistatic synthetic aperture radar systems

    NASA Astrophysics Data System (ADS)

    Adams, J. W.; Schifani, T. M.

    The signal phase histories at the transmitter, receiver, and radar signal processor in bistatic SAR systems are described. The fundamental problem of mismatches in the waveform generators for the illuminating and receiving radar systems is analyzed. The effects of errors in carrier frequency and chirp slope are analyzed for bistatic radar systems which use linear FM waveforms. It is shown that the primary effect of a mismatch in carrier frequencies is an azimuth displacement of the image.

  12. Synthetic Aperture Radar (SAR) data processing

    NASA Technical Reports Server (NTRS)

    Beckner, F. L.; Ahr, H. A.; Ausherman, D. A.; Cutrona, L. J.; Francisco, S.; Harrison, R. E.; Heuser, J. S.; Jordan, R. L.; Justus, J.; Manning, B.

    1978-01-01

    The available and optimal methods for generating SAR imagery for NASA applications were identified. The SAR image quality and data processing requirements associated with these applications were studied. Mathematical operations and algorithms required to process sensor data into SAR imagery were defined. The architecture of SAR image formation processors was discussed, and technology necessary to implement the SAR data processors used in both general purpose and dedicated imaging systems was addressed.

  13. a Robust Change Detector for Multilook Polarimetric Synthetic Aperture Radar Data

    NASA Astrophysics Data System (ADS)

    Ghanbari; Akbari; Abkar; Sahebi; Liu

    2014-10-01

    In this paper, we propose a robust unsupervised change detection algorithm for multilook polarimetric synthetic aperture radar (PolSAR) data. The Hotelling-Lawley trace (HLT) statistic is used as a test statistic to measure the similarity of two covariance matrices. The generalized Kittler and Illingworth (K&I) minimum-error thresholding algorithm is then applied on the test statistic image to accurately discriminates changed and unchanged areas. The algorithm, tested on real PolSAR images, provides satisfactory results.

  14. Imaging radar for bridge deck inspection

    SciTech Connect

    Warhus, J.; Mast, J.; Nelson, S.

    1995-04-13

    Lawrence Livermore National Laboratory (LLNL)l is developing a prototype imaging radar for inspecting steel reinforced concrete bridge decks. The system is designed to acquire Synthetic Aperture Radar (SAR) data and provide high-resolution images of internal structure, flaws, and defects enabling bridge inspectors to nondestructively evaluate and characterize bridge deck condition. Concrete delamination resulting from corrosion of steel reinforcing bars (rebars) is an important structural defect that the system is designed to detect. The prototype system uses arrays of compact, low-cost Micropower Impulse Radar (MIR) modules, supported by appropriate data acquisition and storage subsystems, to generate and collect the radar data, and unique imaging codes to reconstruct images of bridge deck internals. In this paper, we provide an overview of the prototype system concept, discuss its expected performance, and present recent experimental results showing the capability of this approach to detect thin delamination simulations embedded in concrete.

  15. Snow mapping in alpine regions with synthetic aperture radar

    SciTech Connect

    Shi, J.; Dozier, J. ); Rott, H. . Inst. for Meteorology and Geophysics)

    1994-01-01

    For climatological and hydrological investigations, the areas covered by snow and glacial ice are important parameters. Active microwave sensors can discriminate snow from other surfaces in all weather conditions, and their spatial resolution is compatible with the topographic variation in alpine regions. Using data acquired with the NASA AIRSAR in the Oetztal Alps in 1989 and 1991, the authors examine the usage of synthetic aperture radar (SAR) to map snow- and glacier-covered areas. By comparing polarimetric SAR data to images from the Landsat Thematic Mapper obtained under clear conditions one week after the SAR flight, they find that SAR data at 5.3 GHz (C-band) can discriminate between areas covered by snow from those that are ice-free. However, they are less suited to discrimination of glacier ice from snow and rock. The overall pixel-by-pixel accuracies--74% from VV polarization alone with topographic information, 76% from polarimetric SAR without any topographic information, and 79% from polarimetric SAR with topographic information--are high enough to justify the use of SAR as the data source in areas that are too cloud-covered to obtain data from the Thematic Mapper. This is especially true for snow discrimination, where accuracies exceed 80%, because mapping of a transient snow cover during a cloudy melt season is often difficult with an optical sensor. The AIRSAR survey was carried out in summer during a heavy rainstorm, when the snow surfaces were unusually rough.

  16. Mapping Boreal Wetlands Using Spaceborne Synthetic Aperture Radar

    NASA Astrophysics Data System (ADS)

    Podest, E.; McDonald, K. C.; Bohn, T.; Lettenmaier, D.

    2006-12-01

    Carbon and methane emissions from wetlands and lakes can have a large impact on global climate. These ecosystems are dominant features in the northern high latitudes hence the importance of assessing their spatial and temporal extent to improve upon global net carbon exchange estimates. Spaceborne synthetic aperture radar (SAR) is an effective tool for this purpose since large inaccessible areas can be monitored on a temporal basis regardless of atmospheric conditions or solar illumination and it is sensitive to vegetation and standing water. We employ ERS (C-band, 100 m, VV-polarization) and JERS (L-band, 100 m, HH-polarization) in this study to map wetlands within boreal sub-regions. Large scale L-band SAR mosaics assembled over boreal regions are used with supplementary multi-temporal data for the analysis. Path to path and year to year radiometric differences due predominantly to seasonal changes were a source of confusion. Decision tree classification tools are used to alleviate this problem. Digital elevation models (where available) and derived slope aspect are used to better distinguish drainage patterns. Texture images are used to help differentiate different wetland classes (e.g. fens, bogs, swamps, marshes, and open water). Examples of validated test regions are presented. This work was performed at the Jet Propulsion Laboratory, California Institute of Technology and the University of Washington under contract with the National Aeronautics and Space Administration.

  17. Statistical assessment of model fit for synthetic aperture radar data

    NASA Astrophysics Data System (ADS)

    DeVore, Michael D.; O'Sullivan, Joseph A.

    2001-08-01

    Parametric approaches to problems of inference from observed data often rely on assumed probabilistic models for the data which may be based on knowledge of the physics of the data acquisition. Given a rich enough collection of sample data, the validity of those assumed models can be assessed in a statistical hypothesis testing framework using any of a number of goodness-of-fit tests developed over the last hundred years for this purpose. Such assessments can be used both to compare alternate models for observed data and to help determine the conditions under which a given model breaks down. We apply three such methods, the (chi) 2 test of Karl Pearson, Kolmogorov's goodness-of-fit test, and the D'Agostino-Pearson test for normality, to quantify how well the data fit various models for synthetic aperture radar (SAR) images. The results of these tests are used to compare a conditionally Gaussian model for complex-valued SAR pixel values, a conditionally log-normal model for SAR pixel magnitudes, and a conditionally normal model for SAR pixel quarter-power values. Sample data for these tests are drawn from the publicly released MSTAR dataset.

  18. Target discrimination in synthetic aperture radar using artificial neural networks.

    PubMed

    Principe, J C; Kim, M; Fisher, M

    1998-01-01

    This paper addresses target discrimination in synthetic aperture radar (SAR) imagery using linear and nonlinear adaptive networks. Neural networks are extensively used for pattern classification but here the goal is discrimination. We show that the two applications require different cost functions. We start by analyzing with a pattern recognition perspective the two-parameter constant false alarm rate (CFAR) detector which is widely utilized as a target detector in SAR. Then we generalize its principle to construct the quadratic gamma discriminator (QGD), a nonparametrically trained classifier based on local image intensity. The linear processing element of the QCD is further extended with nonlinearities yielding a multilayer perceptron (MLP) which we call the NL-QGD (nonlinear QGD). MLPs are normally trained based on the L(2) norm. We experimentally show that the L(2) norm is not recommended to train MLPs for discriminating targets in SAR. Inspired by the Neyman-Pearson criterion, we create a cost function based on a mixed norm to weight the false alarms and the missed detections differently. Mixed norms can easily be incorporated into the backpropagation algorithm, and lead to better performance. Several other norms (L(8), cross-entropy) are applied to train the NL-QGD and all outperformed the L(2) norm when validated by receiver operating characteristics (ROC) curves. The data sets are constructed from TABILS 24 ISAR targets embedded in 7 km(2) of SAR imagery (MIT/LL mission 90). PMID:18276330

  19. Detection/tracking of moving targets with synthetic aperture radars

    NASA Astrophysics Data System (ADS)

    Newstadt, Gregory E.; Zelnio, Edmund; Gorham, Leroy; Hero, Alfred O., III

    2010-04-01

    In this work, the problem of detecting and tracking targets with synthetic aperture radars is considered. A novel approach in which prior knowledge on target motion is assumed to be known for small patches within the field of view. Probability densities are derived as priors on the moving target signature within backprojected SAR images, based on the work of Jao.1 Furthermore, detection and tracking algorithms are presented to take advantage of the derived prior densities. It was found that pure detection suffered from a high false alarm rate as the number of targets in the scene increased. Thus, tracking algorithms were implemented through a particle filter based on the Joint Multi-Target Probability Density (JMPD) particle filter2 and the unscented Kalman filter (UKF)3 that could be used in a track-before-detect scenario. It was found that the PF was superior than the UKF, and was able to track 5 targets at 0.1 second intervals with a tracking error of 0.20 +/- 1.61m (95% confidence interval).

  20. High Resolution Ionospheric Mapping Using Spaceborne Synthetic Aperture Radars

    NASA Astrophysics Data System (ADS)

    Meyer, F. J.; Chotoo, K.; Roth, A. P.

    2012-12-01

    Spaceborne Synthetic Aperture Radars (SARs) are imaging radar systems that utilize the Doppler history of signals acquired during satellite flyby to produce high resolution images of the Earth. With modern sensors, operating at frequencies between about 1 GHz (L-band) and 10 GHz (X-band), radar images with resolutions in the meter to sub-meter range can be produced. The presence of the ionosphere is significantly affecting the propagation properties of the microwave signals transmitted by these systems, causing distortions of signal polarization and phase. These distortions can lead to a wide range of imaging artifacts including image range shifts, interferometric phase biases, loss of image focus, change of image geometry, and Faraday rotation. While these artifacts are particularly pronounced at L-band, they are still observable in data acquired at C- or even X-band. In recent years, a wealth of methods for measuring and correcting ionospheric influence were developed. These methods are self-calibration procedures that measure ionosphere-induced distortions to infer the two-dimensional TEC maps that affected the data. These TEC maps are then removed from the data to produce high performance SAR images. Besides being effective in correcting SAR observations, these self-calibration methods are producing high quality TEC information with sub-TECU sensitivity and sub-kilometer spatial resolution. The intent of this paper is to utilize SAR-derived ionospheric information and make the case for SAR as a data source for ionospheric research. After a short summary of ionosphere-induced distortions, the concept of TEC estimation from SAR is introduced. Here, the current state-of-the-art of ionospheric TEC estimation is presented, including Faraday rotation-based, interferometric, correlation-based, and autofocus-based techniques. For every approach, performance numbers are given that quantify the achievable TEC estimation accuracy as a function of system parameters, scene

  1. Space Radar Image Of Kennedy Space Center, Florida

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This image was produced during radar observations taken by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar as it flew over the Gulf Stream, Florida, and past the Atlantic Ocean on October 7, 1994. The data were produced using the X-band radar frequency. Knowing ahead of time that this region would be included in a regularly scheduled radar pass, the Kennedy Space Center team, who assembled and integrated the SIR-C/X-SAR equipment with the Spacelab pallet system, designed a set of radar reflectors from common construction materials and formed the letters 'KSC

  2. Smart antennas for space-borne synthetic aperture radars

    NASA Astrophysics Data System (ADS)

    Qin, F.; Gao, S.; Mao, C.; Wang, Z.; Patyuchenko, A.; Younis, M.; Krieger, G.

    2015-11-01

    This paper discusses smart antennas for space-borne synthetic aperture radar (SAR). First, some recent development in smart antennas for space-borne SAR is reviewed. Then, the paper presents a low-cost space-borne SAR system using digital beam forming on receive. The smart antenna system is also discussed, and some results are shown. The antenna system, consisting of a parabolic reflector and multi-feed array, is designed and optimized for dual-band dual-polarized digital beam-forming performance. The operating frequencies are at X and Ka bands with the center frequency of 9.6 and 35.75 GHz, respectively. The stacked dipoles and square patches with parasitic elements are employed as the feed elements at X and Ka bands. Dual-band antenna arrays are combined in the same aperture, which not only reduce the aperture of the feed array, but also coincide the center of dual-band feed arrays.

  3. Ice island detection and characterization with airborne synthetic aperture radar

    SciTech Connect

    Jeffries, M.O.; Sackinger, W.M. )

    1990-04-15

    A 1:300,000 scale airborne synthetic aperture radar (SAR) image of an area of the Arctic Ocean adjacent to the Queen Elizabeth Islands, Canadian High Arctic, is examined to determine the number and characteristics of ice islands in the image and to assess the capability of airborne and satellite SAR to detect ice islands. Twelve ice islands have been identified, and their dimensions range from as large as 5.7 km by 8.7 km to as small as 0.15 km by 0.25 km. A significant SAR characteristic of the shelf ice portions of ice islands is a return with a ribbed texture of alternating lighter and darker grey tones resulting from the indulating shelf ice surfaces of the ice islands. The appearance of the ribbed texture varies according to the ice islands' orientation relative to the illumination direction and consequently the incidence angle. Some ice islands also include extensive areas of textureless dark tone attached to the shelf ice. The weak returns correspond to (1) multiyear landfast sea ice that was attached to the front of the Ward Hunt Ice Shelf at the time of calving and which has remained attached since then and (2) multiyear pack ice that has become attached and consolidated since the calving, indicating that ice islands can increase their area and mass significantly as they drift. Ice islands are easily discernible in SAR images and for the future SAR represents a promising technique to obtain a census of ice islands in the Arctic Ocean. However, any SAR-based census probably will be conservative because ice islands smaller than 300-400 m across are likely to remain undetected, particularly in areas of heavy ice ridging which produces strong SAR clutter.

  4. X-SAR: The X-band synthetic aperture radar on board the Space Shuttle

    NASA Technical Reports Server (NTRS)

    Werner, Marian U.

    1993-01-01

    The X-band synthetic aperture radar (X-SAR) is the German/Italian contribution to the NASA/JPL Shuttle Radar Lab missions as part of the preparation for the Earth Observation System (EOS) program. The Shuttle Radar Lab is a combination of several radars: an L-band (1.2 GHz) and a C-band (5.3 GHz) multipolarization SAR known as SIR-C (Shuttle Imaging Radar); and an X-band (9.6 GHz) vertically polarized SAR which will be operated synchronously over the same target areas to deliver calibrated multifrequency and multipolarization SAR data at multiple incidence angles from space. A joint German/Italian project office at DARA (German Space Agency) is responsible for the management of the X-SAR project. The space hardware has been developed and manufactured under industrial contract by Dornier and Alenia Spazio. Besides supporting all the technical and scientific tasks, DLR, in cooperation with ASI (Agencia Spaziale Italiano) is responsible for mission operation, calibration, and high precision SAR processing. In addition, DLR developed an airborne X-band SAR to support the experimenters with campaigns to prepare for the missions. The main advantage of adding a shorter wavelength (3 cm) radar to the SIR-C radars is the X-band radar's weaker penetration into vegetation and soil and its high sensitivity to surface roughness and associated phenomena. The performance of each of the three radars is comparable with respect to radiometric and geometric resolution.

  5. X-SAR: The X-band synthetic aperture radar on board the Space Shuttle

    NASA Astrophysics Data System (ADS)

    Werner, Marian U.

    1993-05-01

    The X-band synthetic aperture radar (X-SAR) is the German/Italian contribution to the NASA/JPL Shuttle Radar Lab missions as part of the preparation for the Earth Observation System (EOS) program. The Shuttle Radar Lab is a combination of several radars: an L-band (1.2 GHz) and a C-band (5.3 GHz) multipolarization SAR known as SIR-C (Shuttle Imaging Radar); and an X-band (9.6 GHz) vertically polarized SAR which will be operated synchronously over the same target areas to deliver calibrated multifrequency and multipolarization SAR data at multiple incidence angles from space. A joint German/Italian project office at DARA (German Space Agency) is responsible for the management of the X-SAR project. The space hardware has been developed and manufactured under industrial contract by Dornier and Alenia Spazio. Besides supporting all the technical and scientific tasks, DLR, in cooperation with ASI (Agencia Spaziale Italiano) is responsible for mission operation, calibration, and high precision SAR processing. In addition, DLR developed an airborne X-band SAR to support the experimenters with campaigns to prepare for the missions. The main advantage of adding a shorter wavelength (3 cm) radar to the SIR-C radars is the X-band radar's weaker penetration into vegetation and soil and its high sensitivity to surface roughness and associated phenomena. The performance of each of the three radars is comparable with respect to radiometric and geometric resolution.

  6. Synthetic aperture sonar image statistics

    NASA Astrophysics Data System (ADS)

    Johnson, Shawn F.

    Synthetic Aperture Sonar (SAS) systems are capable of producing photograph quality seafloor imagery using a lower frequency than other systems of comparable resolution. However, as with other high-resolution sonar systems, SAS imagery is often characterized by heavy-tailed amplitude distributions which may adversely affect target detection systems. The constant cross-range resolution with respect to range that results from the synthetic aperture formation process provides a unique opportunity to improve our understanding of system and environment interactions, which is essential for accurate performance prediction. This research focused on the impact of multipath contamination and the impact of resolution on image statistics, accomplished through analyses of data collected during at-sea experiments, analytical modeling, and development of numerical simulations. Multipath contamination was shown to have an appreciable impact on image statistics at ranges greater than the water depth and when the levels of the contributing multipath are within 10 dB of the direct path, reducing the image amplitude distribution tails while also degrading image clarity. Image statistics were shown to depend strongly upon both system resolution and orientation to seafloor features such as sand ripples. This work contributes to improving detection systems by aiding understanding of the influences of background (i.e. non-target) image statistics.

  7. Tundra Fire Effects Mapping from Synthetic Aperture Radar Satellite Data

    NASA Astrophysics Data System (ADS)

    Jenkins, L. K.; Bourgeau-Chavez, L. L.; French, N. H.; Loboda, T. V.; Chavez, M. C.; Hawkins, S. M.

    2013-12-01

    Traditional electro-optical, satellite-based methods of fire detection and monitoring are severely limited in the arctic due to persistent cloud cover and short growing seasons. Radar data can provide an alternative to traditional electro-optical methods due to all-weather imaging capabilities. Previous research in boreal forests and current evaluation in the Alaskan tundra shows that synthetic aperture radar (SAR) data can be used successfully to map burn perimeters and distinguish burned and unburned areas within the perimeter over a longer period of time than optical sensors. Results will be presented on the use of SAR data to measure spatial variations in the microwave signature across a fire scar as well as temporally throughout the growing season and across multiple years. The extensive historical archive of ERS-1 and -2 SAR data has been used to characterize three burned areas in the tundra regions of Alaska. These fires include the 1993 Wainwright fires in the north-western part of the North Slope (Fig 1), the 1999 Uvgoon fire in the Noatak National Preserve and 2007 Anaktuvuk River fire north of the Brooks Range in the central area of the North Slope. The data record includes pre-burn, burn, and post-burn observations until the fire scars are no longer discernible on the landscape. Our results show that burned areas are visible reliably five years post burn and then faintly apparent thereafter up to 12 or more years post-burn. Conversely, our analysis of electro-optical (Landsat) imagery shows near complete obscuration of the fire scar one year post-burn (Loboda et al. 2013). Also presented are results of an analysis of the effects of post-fire soil moisture, as measured in weather and climate datasets, on the SAR signature measured from the available image data archive. Reference: Loboda, T L, N H F French, C Hight-Harf, L Jenkins, M E Miller. 2013. Mapping fire extent and burn severity in Alaskan tussock tundra: An analysis of the spectral response of

  8. Model-Based Information Extraction From Synthetic Aperture Radar Signals

    NASA Astrophysics Data System (ADS)

    Matzner, Shari A.

    2011-07-01

    Synthetic aperture radar (SAR) is a remote sensing technology for imaging areas of the earth's surface. SAR has been successfully used for monitoring characteristics of the natural environment such as land cover type and tree density. With the advent of higher resolution sensors, it is now theoretically possible to extract information about individual structures such as buildings from SAR imagery. This information could be used for disaster response and security-related intelligence. SAR has an advantage over other remote sensing technologies for these applications because SAR data can be collected during the night and in rainy or cloudy conditions. This research presents a model-based method for extracting information about a building -- its height and roof slope -- from a single SAR image. Other methods require multiple images or ancillary data from specialized sensors, making them less practical. The model-based method uses simulation to match a hypothesized building to an observed SAR image. The degree to which a simulation matches the observed data is measured by mutual information. The success of this method depends on the accuracy of the simulation and on the reliability of the mutual information similarity measure. Electromagnetic theory was applied to relate a building's physical characteristics to the features present in a SAR image. This understanding was used to quantify the precision of building information contained in SAR data, and to identify the inputs needed for accurate simulation. A new SAR simulation technique was developed to meet the accuracy and efficiency requirements of model-based information extraction. Mutual information, a concept from information theory, has become a standard for measuring the similarity between medical images. Its performance in the context of matching a simulation image to a SAR image was evaluated in this research, and it was found to perform well under certain conditions. The factors that affect its performance

  9. Spaceborne Imaging Radar Symposium

    NASA Technical Reports Server (NTRS)

    Elachi, C.

    1983-01-01

    An overview of the present state of the art in the different scientific and technological fields related to spaceborne imaging radars was presented. The data acquired with the SEASAT SAR (1978) and Shuttle Imaging Radar, SIR-A (1981) clearly demonstrated the important emphasis in the 80's is going to be on in-depth research investigations conducted with the more flexible and sophisticated SIR series instruments and on long term monitoring of geophysical phenomena conducted from free-flying platforms such as ERS-1 and RADARSAT.

  10. Ambiguities in spaceborne synthetic aperture radar systems

    NASA Technical Reports Server (NTRS)

    Li, F. K.; Johnson, W. T. K.

    1983-01-01

    An examination of aspects of spaceborne SAR time delay and Doppler ambiguities has led to the formulation of an accurate method for the evaluation of the ratio of ambiguity intensities to that of the signal, which has been applied to the nominal SAR system on Seasat. After discussing the variation of this ratio as a function of orbital latitude and attitude control error, it is shown that the detailed range migration-azimuth phase history of an ambiguity is different from that of a signal, so that the images of ambiguities are dispersed. Seasat SAR dispersed images are presented, and their dispersions are eliminated through an adjustment of the processing parameters. A method is also presented which uses a set of multiple pulse repetition sequences to determine the Doppler centroid frequency absolute values for SARs with high carrier frequencies and poor attitude measurements.

  11. NASA-ISRO synthetic aperture radar: science and applications

    NASA Astrophysics Data System (ADS)

    Kumar, Raj; Rosen, Paul; Misra, Tapan

    2016-05-01

    NASA-ISRO Synthetic Aperture Radar (NISAR), a novel SAR concept will be utilized to image wide swath at high resolution of stripmap SAR. It will have observations in L- and S-bands to understand highly spatial and temporally complex processes such as ecosystem disturbances, ice sheet changes, and natural hazards including earthquakes, tsunamis, volcanoes, and landslides. NISAR with several advanced features such as 12 days interferometric orbit, achievement of high resolution and wide swath images through SweepSAR technology and simultaneous data acquisition in dual frequency would support a host of applications. The primary objectives of NISAR are to monitor ecosystems including monitoring changes in ecosystem structure and biomass estimation, carbon flux monitoring; mangroves and wetlands characterization; alpine forest characterization and delineation of tree-line ecotone, land surface deformation including measurement of deformation due to co-seismic and inter-seismic activities; landslides; land subsidence and volcanic deformation, cryosphere studies including measurements of dynamics of polar ice sheet, ice discharge to the ocean, Himalayan snow and glacier dynamics, deep and coastal ocean studies including retrieval of ocean parameters, mapping of coastal erosion and shore-line change; demarcation of high tide line (HTL) and low tide line (LTL) for coastal regulation zones (CRZ) mapping, geological studies including mapping of structural and lithological features; lineaments and paleo-channels; geo-morphological mapping, natural disaster response including mapping and monitoring of floods, forest fires, oil spills, earthquake damage and monitoring of extreme weather events such as cyclones. In addition to the above, NISAR would support various other applications such as enhanced crop monitoring, soil moisture estimation, urban area development, weather and hydrological forecasting.

  12. Space Radar Image of Long Island Optical/Radar

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This pair of images of the Long Island, New York region is a comparison of an optical photograph (top) and a radar image (bottom), both taken in darkness in April 1994. The photograph at the top was taken by the Endeavour astronauts at about 3 a.m. Eastern time on April 20, 1994. The image at the bottom was acquired at about the same time four days earlier on April 16,1994 by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) system aboard the space shuttle Endeavour. Both images show an area approximately 100 kilometers by 40 kilometers (62 miles by 25 miles) that is centered at 40.7 degrees North latitude and 73.5 degrees West longitude. North is toward the upper right. The optical image is dominated by city lights, which are particularly bright in the densely developed urban areas of New York City located on the left half of the photo. The brightest white zones appear on the island of Manhattan in the left center, and Central Park can be seen as a darker area in the middle of Manhattan. To the northeast (right) of the city, suburban Long Island appears as a less densely illuminated area, with the brightest zones occurring along major transportation and development corridors. Since radar is an active sensing system that provides its own illumination, the radar image shows a great amount of surface detail, despite the night-time acquisition. The colors in the radar image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted and vertically received); blue represents the C-band (horizontally transmitted and vertically received). In this image, the water surface - the Atlantic Ocean along the bottom edge and Long Island Sound shown at the top edge - appears red because small waves at the surface strongly reflect the horizontally transmitted and received L-band radar signal. Networks of highways and railroad lines are clearly

  13. Space Radar Image of Munich, Germany

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This spaceborne radar image of Munich, Germany illustrates the capability of a multi-frequency radar system to highlight different land use patterns in the area surrounding Bavaria's largest city. Central Munich is the white area at the middle of the image, on the banks of the Isar River. Pink areas are forested, while green areas indicate clear-cut and agricultural terrain. The Munich region served as a primary 'supersite' for studies in ecology, hydrology and radar calibration during the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) missions. Scientists were able to use these data to map patterns of forest damage from storms and areas affected by bark beetle infestation. The image was acquired by SIR-C/X-SAR onboard the space shuttle Endeavour on April 18, 1994. The image is 37 kilometers by 32 kilometers (23 miles by 20 miles) and is centered at 48.2 degrees North latitude, 11.5 degrees East longitude. North is toward the upper right. The colors are assigned to different radar frequencies and polarizations of the radar as follows: red is L-band, vertically transmitted and horizontally received; green is C-band, vertically transmitted and horizontally received; and blue is C-band vertically transmitted and received. SIR-C/X-SAR, a joint mission of the German, Italian, and United States space agencies, is part of NASA's Mission to Planet Earth.

  14. Reduction and coding of synthetic aperture radar data with Fourier transforms

    NASA Technical Reports Server (NTRS)

    Tilley, David G.

    1995-01-01

    Recently, aboard the Space Radar Laboratory (SRL), the two roles of Fourier Transforms for ocean image synthesis and surface wave analysis have been implemented with a dedicated radar processor to significantly reduce Synthetic Aperture Radar (SAR) ocean data before transmission to the ground. The object was to archive the SAR image spectrum, rather than the SAR image itself, to reduce data volume and capture the essential descriptors of the surface wave field. SAR signal data are usually sampled and coded in the time domain for transmission to the ground where Fourier Transforms are applied both to individual radar pulses and to long sequences of radar pulses to form two-dimensional images. High resolution images of the ocean often contain no striking features and subtle image modulations by wind generated surface waves are only apparent when large ocean regions are studied, with Fourier transforms, to reveal periodic patterns created by wind stress over the surface wave field. Major ocean currents and atmospheric instability in coastal environments are apparent as large scale modulations of SAR imagery. This paper explores the possibility of computing complex Fourier spectrum codes representing SAR images, transmitting the coded spectra to Earth for data archives and creating scenes of surface wave signatures and air-sea interactions via inverse Fourier transformations with ground station processors.

  15. Atmospheric Phenomena Observed Over The South China Sea By The Advanced Synthetic Aperture Radar Onboard the ENVISAT Satellite

    NASA Astrophysics Data System (ADS)

    Alpers, Werner; Huang, Weigen; Chan, Pak Wai; Wong, Wai Kin; Cheng, Cho Ming; Mouche, Alexis

    2010-10-01

    Atmospheric phenomena often leave fingerprints on the sea surface, which are detectable by synthetic aperture radar (SAR). Here we present some representative examples of SAR images acquired by the Advanced Synthetic Aperture Radar (ASAR) onboard the Envisat satellite over the South China Sea (SCS) which show radar signatures of atmospheric gravity waves (AGWs) and of coastal wind fields. On SAR images of the SCS also often radar signatures of oceanic internal waves (OIWs) are visible which have similar spatial scales as the ones originating from AGWs. Therefore we first present criteria how to distinguish between them by analyzing the structure of the radar signatures. Then we present two examples of ASAR images which show radar signatures of AGWs over the SCS. Furthermore, we present a SAR image showing radar signatures of a northerly Winter Monsoon surge event over the coastal area south of Hong Kong and compare it with a cloud image and a weather radar image. From the ASAR image we retrieve the near-surface wind field and compare it with the wind field simulated by the AIR model of the Hong Kong Observatory. The comparison shows that the AIR model can simulate quite well the wind speed as well as the position and shape of the frontal line measured by ASAR.

  16. Distress detection, location, and communications using advanced space technology. [satellite-borne synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Sivertson, W. E., Jr.

    1977-01-01

    This paper briefly introduces a concept for low-cost, global, day-night, all-weather disaster warning and assistance. Evolving, advanced space technology with passive radio frequency reflectors in conjunction with an imaging synthetic aperture radar is employed to detect, identify, locate, and provide passive communication with earth users in distress. This concept evolved from a broad NASA research on new global search and rescue techniques. Appropriate airborne radar test results from this research are reviewed and related to potential disaster applications. The analysis indicates the approach has promise for disaster communications relative to floods, droughts, earthquakes, volcanic eruptions, and severe storms.

  17. A parametric study of rate of advance and area coverage rate performance of synthetic aperture radar.

    SciTech Connect

    Raynal, Ann Marie; Hensley, William Heydon,; Burns, Bryan L.; Doerry, Armin Walter

    2014-11-01

    The linear ground distance per unit time and ground area covered per unit time of producing synthetic aperture radar (SAR) imagery, termed rate of advance (ROA) and area coverage rate (ACR), are important metrics for platform and radar performance in surveillance applications. These metrics depend on many parameters of a SAR system such as wavelength, aircraft velocity, resolution, antenna beamwidth, imaging mode, and geometry. Often the effects of these parameters on rate of advance and area coverage rate are non-linear. This report addresses the impact of different parameter spaces as they relate to rate of advance and area coverage rate performance.

  18. Evaluation of synthetic aperture radar for oil-spill response. Final report, June 1992-September 1993

    SciTech Connect

    Hover, G.L.; Mastin, G.A.; Axline, R.M.; Bradley, J.D.

    1993-10-01

    This report provides a detailed evaluation of synthetic aperture radar (SAR) as a potential technology improvement over the Coast Guard's existing side-looking airborne radar (SLAR) for oil-spill surveillance applications. The U.S. Coast Guard Research and Development Center (RD Center), Environmental Safety Branch, sponsored a joint experiment including the U.S. Coast Guard, Sandia National Laboratories, and the National Oceanographic and Atmospheric Administration (NOAA), Hazardous Materials Division. Radar imaging missions were flown on six days over the coastal waters off Santa Barbara, CA, where there are constant natural seeps of oil. Both the Coast Guard SLAR and the Sandia National Laboratories SAR were employed to acquire simultaneous images of oil slicks and other natural sea surface features that impact oil-spill interpretation. Surface truth and other environmental data were also recorded during the experiment. The experiment data were processed at Sandia National Laboratories and delivered to the RD Center on a PC-based computer workstation for analysis by experiment participants. Synthetic aperture radar, Side looking airborne radar, Oil slicks.

  19. Reconstruction of coded aperture images

    NASA Technical Reports Server (NTRS)

    Bielefeld, Michael J.; Yin, Lo I.

    1987-01-01

    Balanced correlation method and the Maximum Entropy Method (MEM) were implemented to reconstruct a laboratory X-ray source as imaged by a Uniformly Redundant Array (URA) system. Although the MEM method has advantages over the balanced correlation method, it is computationally time consuming because of the iterative nature of its solution. Massively Parallel Processing, with its parallel array structure is ideally suited for such computations. These preliminary results indicate that it is possible to use the MEM method in future coded-aperture experiments with the help of the MPP.

  20. Space Radar Image of Phnom Phen, Cambodia

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This spaceborne radar image shows the city of Phnom Penh, the capital of Cambodia. Phnom Penh lies at the confluence of the Mekong River and the Basak Sab. The city was originally established in 1434 to succeed Angkor Thom as capital of the Khmer Nation. Phnom Penh is the bright blue and orange area west of the rivers, near the center of the image. The red, light blue and purple colors indicate differences in vegetation height and structure. Radar images like this one are being used by archaeologists to investigate ruins in the Angkor area in northern Cambodia. This image was acquired by Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on April 15, 1994. The image is 27 kilometers by 27 kilometers (17 miles by 17 miles) and is centered at 11.5 degrees north latitude, 105.0 degrees East longitude. North is toward the upper right. The colors are assigned to different radar frequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted and received; green is L-band, horizontally transmitted and vertically received; and blue is C-band, horizontally transmitted and vertically received. SIR-C/X-SAR, a joint mission of the German, Italian, and United States space agencies, is part of NASA's Mission to Planet Earth.

  1. Radar image of Rio Sao Francisco, Brazil

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This radar image acquired by SRTM shows an area south of the Sao Francisco River in Brazil. The area is predominantly scrub forest. Areas such as these are difficult to map by traditional methods because of frequent cloud cover and local inaccessibility. Image brightness differences in this image are caused by differences in vegetation type and density. Tributaries of the Sao Francisco are visible in the upper right. The Sao Francisco River is a major source of water for irrigation and hydroelectric power. Mapping such regions will allow scientists to better understand the relationships between flooding cycles, forestation and human influences on ecosystems.

    This radar image was obtained by the Shuttle Radar Topography Mission as part of its mission to map the Earth's topography. The image was acquired by just one of SRTM's two antennas, and consequently does not show topographic data but only the strength of the radar signal reflected from the ground. This signal, known as radar backscatter, provides insight into the nature of the surface, including its roughness, vegetation cover, and urbanization.

    The Shuttle Radar Topography Mission (SRTM), launched on February 11, 2000, uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission is designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, an additional C-band imaging antenna and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.

  2. Synthetic Aperture Radar Interferometry to Measure Earth's Surface Topography and Its Deformation

    NASA Astrophysics Data System (ADS)

    Bürgmann, Roland; Rosen, Paul A.; Fielding, Eric J.

    Synthetic aperture radar interferometry (InSAR) from Earth-orbiting spacecraft provides a new tool to map global topography and deformation of the Earth's surface. Radar images taken from slightly different viewing directions allow the construction of digital elevation models of meter-scale accuracy. These data sets aid in the analysis and interpretation of tectonic and volcanic landscapes. If the Earth's surface deformed between two radar image acquisitions, a map of the surface displacement with tens-of-meters resolution and subcentimeter accuracy can be constructed. This review gives a basic overview of InSAR for Earth scientists and presents a selection of geologic applications that demonstrate the unique capabilities of InSAR for mapping the topography and deformation of the Earth.

  3. Signal based motion compensation for synthetic aperture radar

    SciTech Connect

    John Kirk

    1999-06-07

    The purpose of the Signal Based Motion Compensation (SBMC) for Synthetic Aperture Radar (SAR) effort is to develop a method to measure and compensate for both down range and cross range motion of the radar in order to provide high quality focused SAR imagery in the absence of precision measurements of the platform motion. Currently SAR systems require very precise navigation sensors for motion compensation. These sensors are very expensive and are often supplied in pairs for reliability. In the case of GPS they can be jammed, further degrading performance. This makes for a potentially very expensive and possibly vulnerable SAR system. SBMC can eliminate or reduce the need for these expensive navigation sensors thus reducing the cost of budget minded SAR systems. The results on this program demonstrated the capability of the SBMC approach.

  4. Seasat synthetic aperture radar - Ocean wave detection capabilities

    NASA Technical Reports Server (NTRS)

    Gonzalez, F. I.; Beal, R. C.; Brown, W. E.; Deleonibus, P. S.; Sherman, J. W., III; Gower, J. F. R.; Lichy, D.; Ross, D. B.; Rufenach, C. L.; Shuchman, R. A.

    1979-01-01

    A preliminary assessment has been made of the capability of the Seasat synthetic aperture radar to detect ocean waves. Comparison with surface and aircraft measurements from five passes of the satellite over the Gulf of Alaska indicates agreement to within about 15 percent in wavelength and about 25 deg in wave direction. These results apply to waves 100 to 250 meters in length, propagating in a direction predominantly across the satellite track, in sea states with significant wave height in a range of 2 to 3.5 meters.

  5. Addendum to proceedings of the 1978 Synthetic Aperture Radar Technology Conference

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Various research projects on synthetic aperture radar are reported, including SAR calibration techniques. Slot arrays, sidelobe suppression, and wide swaths on satellite-borne radar were examined. The SAR applied to remote sensing was also considered.

  6. Experiment in Onboard Synthetic Aperture Radar Data Processing

    NASA Technical Reports Server (NTRS)

    Holland, Matthew

    2011-01-01

    Single event upsets (SEUs) are a threat to any computing system running on hardware that has not been physically radiation hardened. In addition to mandating the use of performance-limited, hardened heritage equipment, prior techniques for dealing with the SEU problem often involved hardware-based error detection and correction (EDAC). With limited computing resources, software- based EDAC, or any more elaborate recovery methods, were often not feasible. Synthetic aperture radars (SARs), when operated in the space environment, are interesting due to their relevance to NASAs objectives, but problematic in the sense of producing prodigious amounts of raw data. Prior implementations of the SAR data processing algorithm have been too slow, too computationally intensive, and require too much application memory for onboard execution to be a realistic option when using the type of heritage processing technology described above. This standard C-language implementation of SAR data processing is distributed over many cores of a Tilera Multicore Processor, and employs novel Radiation Hardening by Software (RHBS) techniques designed to protect the component processes (one per core) and their shared application memory from the sort of SEUs expected in the space environment. The source code includes calls to Tilera APIs, and a specialized Tilera compiler is required to produce a Tilera executable. The compiled application reads input data describing the position and orientation of a radar platform, as well as its radar-burst data, over time and writes out processed data in a form that is useful for analysis of the radar observations.

  7. Calibration and characterisation of spaceborne synthetic aperture radars (SAR)

    NASA Astrophysics Data System (ADS)

    Carter, D. J. Q.; Hurd, D. L.; Cordey, R. A.

    1997-05-01

    Applications of Synthetic Aperture Radar (SAR) data are many and varied. The emergence of SAR as a commercially viable commodity is also focusing needs to provide services to fulfil applications at affordable prices. This then drives the need to include only features in the system that are necessary and to arrive at designs which are cost efficient to produce. The purposes of Calibration are two fold; (1) conversion of the Radar output units into predetermined reference units (2) the measurement of dynamic system characteristics which fluctuate throughout the life of the system to enable correction of the final product for such features. The first is largely application driven whereas the second is dominated by the system implementation. It is necessary that the spaceborne radar design is not too difficult to realise but this must be balanced by the burden that a simple design may impose upon the ground processing. Definitions of Calibration and Characterisation are provided and discussions of the needs in terms of applications and demands presented. The aspects of implementation for different Radar design families are presented with examples from current programmes.

  8. space Radar Image of Long Valley, California

    NASA Technical Reports Server (NTRS)

    1994-01-01

    An area near Long Valley, California, was mapped by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar aboard the space shuttle Endeavor on April 13, 1994, during the first flight of the radar instrument, and on October 4, 1994, during the second flight of the radar instrument. The orbital configurations of the two data sets were ideal for interferometric combination -- that is overlaying the data from one image onto a second image of the same area to create an elevation map and obtain estimates of topography. Once the topography is known, any radar-induced distortions can be removed and the radar data can be geometrically projected directly onto a standard map grid for use in a geographical information system. The 50 kilometer by 50 kilometer (31 miles by 31 miles) map shown here is entirely derived from SIR-C L-band radar (horizontally transmitted and received) results. The color shown in this image is produced from the interferometrically determined elevations, while the brightness is determined by the radar backscatter. The map is in Universal Transverse Mercator (UTM) coordinates. Elevation contour lines are shown every 50 meters (164 feet). Crowley Lake is the dark feature near the south edge of the map. The Adobe Valley in the north and the Long Valley in the south are separated by the Glass Mountain Ridge, which runs through the center of the image. The height accuracy of the interferometrically derived digital elevation model is estimated to be 20 meters (66 feet) in this image. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global

  9. Inverse-synthetic-aperture imaging of trees over a ground plane

    SciTech Connect

    Zittel, D.H.; Brock, B.C.; Littlejohn, J.H.; Patitz, W.E.

    1995-11-01

    Recent data collections with the Sandia VHF-UHF synthetic-aperture radar have yielded surprising results; trees appear brighter in the images than expected! In an effort to understand this phenomenon, various small trees have been measured on the Sandia folded compact range with the inverse-synthetic-aperture imaging system. A compilation of these measurements is contained in this report.

  10. Space Radar Image of Chernobyl

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is an image of the Chernobyl nuclear power plant and its surroundings, centered at 51.17 north latitude and 30.15 west longitude. The image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar aboard the space shuttle Endeavour on its 16th orbit on October 1, 1994. The area is located on the northern border of the Ukraine Republic and was produced by using the L-band (horizontally transmitted and received) polarization. The differences in the intensity are due to differences in vegetation cover, with brighter areas being indicative of more vegetation. These data were acquired as part of a collaboration between NASA and the National Space Agency of Ukraine in Remote Sensing and Earth Sciences. NASA has included several sites provided by the Ukrainian space agency as targets of opportunity during the second flight of SIR-C/X-SAR. The Ukrainian space agency also plans to conduct airborne surveys of these sites during the mission. The Chernobyl nuclear power plant is located toward the top of the image near the Pripyat River. The 12-kilometer (7.44-mile)-long cooling pond is easily distinguishable as an elongated dark shape in the center near the top of the image. The reactor complex is visible as the bright area to the extreme left of the cooling pond and the city of Chernobyl is the bright area just below the cooling pond next to the Pripyat River. The large dark area in the bottom right of the image is the Kiev Reservoir just north of Kiev. Also visible is the Dnieper River, which feeds into the Kiev Reservoir from the top of the image. The Soviet government evacuated 116,000 people within 30 kilometers (18.6 miles) of the Chernobyl reactor after the explosion and fire on April 26, 1986. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight

  11. Venus radar images

    NASA Technical Reports Server (NTRS)

    Goldstein, R. M.; Green, R. R.; Rumsey, H. C.

    1976-01-01

    The paper presents a set of seven radar brightness images and the corresponding altitude contours of small portions (circular regions of 1500-km diameter) of the Venus surface located at the center of the disk taken in the winter of 1973-1974. The regions imaged are arranged in an equatorial belt on the one face of Venus which is always seen on the occasions of closest approach to earth. A real resolution for the images is, typically, 100 x 10 km, while altitude resolution is 500 m.

  12. Interferometric synthetic aperture radar (InSAR)—its past, present and future

    USGS Publications Warehouse

    Lu, Zhong; Kwoun, Oh-Ig; Rykhus, R.P.

    2007-01-01

    Very simply, interferometric synthetic aperture radar (InSAR) involves the use of two or more synthetic aperture radar (SAR) images of the same area to extract landscape topography and its deformation patterns. A SAR system transmits electromagnetic waves at a wavelength that can range from a few millimeters to tens of centimeters and therefore can operate during day and night under all-weather conditions. Using SAR processing technique (Curlander and McDonough, 1991), both the intensity and phase of the reflected (or backscattered) radar signal of each ground resolution element (a few meters to tens of meters) can be calculated in the form of a complex-valued SAR image that represents the reflectivity of the ground surface. The amplitude or intensity of the SAR image is determined primarily by terrain slope, surface roughness, and dielectric constants, whereas the phase of the SAR image is determined primarily by the distance between the satellite antenna and the ground targets. InSAR imaging utilizes the interaction of electromagnetic waves, referred to as interference, to measure precise distances between the satellite antenna and ground resolution elements to derive landscape topography and its subtle change in elevation.

  13. Phase correction system for automatic focusing of synthetic aperture radar

    DOEpatents

    Eichel, Paul H.; Ghiglia, Dennis C.; Jakowatz, Jr., Charles V.

    1990-01-01

    A phase gradient autofocus system for use in synthetic aperture imaging accurately compensates for arbitrary phase errors in each imaged frame by locating highlighted areas and determining the phase disturbance or image spread associated with each of these highlight areas. An estimate of the image spread for each highlighted area in a line in the case of one dimensional processing or in a sector, in the case of two-dimensional processing, is determined. The phase error is determined using phase gradient processing. The phase error is then removed from the uncorrected image and the process is iteratively performed to substantially eliminate phase errors which can degrade the image.

  14. Space Radar Image of Belgrade, Serbia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This spaceborne radar image of Belgrade, Serbia, illustrates the variety of land use patterns that can be observed with a multiple wavelength radar system. Belgrade, the capital of Serbia and former capital of Yugoslavia, is the bright area in the center of the image. The Danube River flows from the top to the bottom of the image, and the Sava River flows into the Danube from the left. Agricultural fields appear in shades of dark blue, purple and brown in outlying areas. Vegetated areas along the rivers appear in light blue-green, while dense forests in hillier areas in the lower left appear in a darker shade of green. The image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on October 2, 1994. The image is centered at 44.5 degrees north latitude and 20.5 degrees east longitude. North is toward the upper right. The image shows an area 36 kilometers by 32 kilometers 22 miles by 20 miles). The colors are assigned to different frequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted, horizontally received; green is L-band, horizontally transmitted, vertically received; blue is C-band, horizontally transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

  15. Space radar image of Ubar optical/radar

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This pair of images from space shows a portion of the southern Empty Quarter of the Arabian Peninsula in the country of Oman. On the left is a radar image of the region around the site of the fabled Lost City of Ubar, discovered in 1992 with the aid of remote sensing data. On the right is an enhanced optical image taken by the shuttle astronauts. Ubar existed from about 2800 BC to about 300 AD. and was a remote desert outpost where caravans were assembled for the transport of frankincense across the desert. The actual site of the fortress of the Lost City of Ubar, currently under excavation, is too small to show in either image. However, tracks leading to the site, and surrounding tracks, show as prominent, but diffuse, reddish streaks in the radar image. Although used in modern times, field investigations show many of these tracks were in use in ancient times as well. Mapping of these tracks on regional remote sensing images provided by the Landsat satellite was a key to recognizing the site as Ubar. The prominent magenta colored area is a region of large sand dunes. The green areas are limestone rocks, which form a rocky desert floor. A major wadi, or dry stream bed, runs across the scene and appears as a white line. The radar images, and ongoing field investigations, will help shed light on an early civilization about which little in known. The radar image was taken by the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) and is centered at 18 degrees North latitude and 53 degrees East longitude. The image covers an area about 50 kilometers by 100 kilometers (31 miles by 62 miles). The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted, horizontally received; blue is C-band horizontally transmitted, horizontally received; green is L-band horizontally transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian and the United

  16. Space Radar Image of Randonia Rain Cell

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This multi-frequency space radar image of a tropical rainforest in western Brazil shows rapidly changing land use patterns and it also demonstrates the capability of the different radar frequencies to detect and penetrate heavy rainstorms. This color image was created by combining the three separate radar frequencies into a composite image. The three black and white images below represent the individual frequencies. The lower left image, X-band vertically transmitted and received, is blue in the color image; the lower center image, C-band horizontally transmitted and vertically received is green; and the lower right image, L-band horizontally transmitted and vertically received is red. A heavy downpour in the lower center of the image appears as a black 'cloud' in the X-band image, the same area is shows up faintly in the C-band image, and is invisible in the L-band image. When combined in the color image, the rain cell appears red and yellow. Although radar can usually 'see' through clouds, short radar wavelengths (high frequency), such as X and C-band, can be changed by unusually heavy rain cells. L-band, at a 24 cm (9 inches) wavelength, is unaffected by such rain cells. By analyzing the way the radar changes, scientist can estimate rainfall rates. The area shown is in the state of Rondonia, in western Brazil. The pink areas are pristine tropical rainforest, and the blue and green patches are areas where the forest has been cleared for agriculture. Cleared areas are typically able to support intense farming for a only few years, before soil erosion renders the fields unusable. Radar imaging can be used to monitor not only the rainforest destruction, but also the rates of recovery of abandoned fields. This image is 35.2 kilometers by 21.3 kilometers (21.8 miles by 13.2 miles) and is centered at 11.2 degrees south latitude, 61.7 degrees west longitude. North is toward the upper left. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic

  17. Operational Use of Civil Space-Based Synthetic Aperture Radar (SAR)

    NASA Technical Reports Server (NTRS)

    Montgomery, Donald R. (Editor)

    1996-01-01

    Synthetic Aperture Radar (SAR) is a remote-sensing technology which uses the motion of the aircraft or spacecraft carrying the radar to synthesize an antenna aperture larger than the physical antenna to yield a high-spatial resolution imaging capability. SAR systems can thus obtain high-spatial resolution geophysical measurements of the Earth over wide surface areas, under all-weather, day/night conditions. This report was prepared to document the results of a six-month study by an Ad Hoc Interagency Working Group on the Operational Use of Civil (i.e., non-military) Space-based Synthetic Aperture Radar (SAR). The Assistant Administrator of NOAA for Satellite and Information Services convened this working group and chaired three meetings of the group over a six-month period. This action was taken in response to a request by the Associate Administrator of NASA for Mission to Planet Earth for an assessment of operational applications of SAR to be accomplished in parallel with a separate study requested of the Committee on Earth Studies of the Space Studies Board of the National Research Council on the scientific results of SAR research missions. The representatives of participating agencies are listed following the Preface. There was no formal charter for the working group or long term plans for future meetings. However, the working group may be reconstituted in the future as a coordination body for multiagency use of operational SAR systems.

  18. Synthetic-Aperture Coherent Imaging From A Circular Path

    NASA Technical Reports Server (NTRS)

    Jin, Michael Y.

    1995-01-01

    Imaging algorithms based on exact point-target responses. Developed for use in reconstructing image of target from data gathered by radar, sonar, or other transmitting/receiving coherent-signal sensory apparatus following circular observation path around target. Potential applications include: Wide-beam synthetic-aperture radar (SAR) from aboard spacecraft in circular orbit around target planet; SAR from aboard airplane flying circular course at constant elevation around central ground point, toward which spotlight radar beam pointed; Ultrasonic reflection tomography in medical setting, using one transducer moving in circle around patient or else multiple transducers at fixed positions on circle around patient; and Sonar imaging of sea floor to high resolution, without need for large sensory apparatus.

  19. Space Radar Image of Bahia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a color composite image of southern Bahia, Brazil, centered at 15.22 degree south latitude and 39.07 degrees west longitude. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar aboard the space shuttle Endeavour on its 38th orbit of Earth on October 2, 1994. The image covers an area centered over the Una Biological Reserve, one the largest protected areas in northeastern Brazil. The 7,000-hectare reserve is administered by the Brazilian Institute for the Environment and is part of the larger Atlantic coastal forest, a narrow band of rain forest extending along the eastern coast of Brazil. The Atlantic coastal forest of southern Bahia is one of the world's most threatened and diverse ecosystems. Due to widespread settlement, only 2 to 5 percent of the original forest cover remains. Yet the region still contains an astounding variety of plants and animals, including a large number of endemic species. More than half of the region's tree species and 80 percent of its animal species are indigenous and found nowhere else on Earth. The Una Reserve is also the only federally protected habitat for the golden-headed lion tamarin, the yellow-breasted capuchin monkey and many other endangered species. In the past few years, scientists from Brazilian and international conservation organizations have coordinated efforts to study the biological diversity of this region and to develop practical and economically viable options for preserving the remaining primary forests in southern Bahia. The shuttle imaging radar is used in this study to identify various land uses and vegetation types, including remaining patches of primary forest, cabruca forest (cacao planted in the understory of the native forest), secondary forest, pasture and coastal mangrove. Standard remote-sensing technology that relies on light reflected from the forest canopy cannot accurately distinguish between cabruca and undisturbed forest. Optical remote sensing is also

  20. Space Radar Image of Bahia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a color composite image of southern Bahia, Brazil, centered at 15.22 degree south latitude and 39.07 degrees west longitude. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar aboard the space shuttle Endeavour on its 38th orbit of Earth on October 2, 1994. The image covers an area centered over the Una Biological Reserve, one the largest protected areas in northeastern Brazil. The 7,000-hectare reserve is administered by the Brazilian Institute for the Environment and is part of the larger Atlantic coastal forest, a narrow band of rain forest extending along the eastern coast of Brazil. The Atlantic coastal forest of southern Bahia is one of the world's most threatened and diverse ecosystems. Due to widespread settlement, only 2 to 5 percent of the original forest cover remains. Yet the region still contains an astounding variety of plants and animals, including a large number of endemic species. More than half of the region's tree species and 80 percent of its animal species are indigenous and found nowhere else on Earth. The Una Reserve is also the only federally protected habitat for the golden-headed lion tamarin, the yellow-breasted capuchin monkey and many other endangered species. In the past few years, scientists from Brazilian and international conservation organizations have coordinated efforts to study the biological diversity of this region and to develop practical and economically viable options for preserving the remaining primary forests in southern Bahia. The shuttle imaging radar is used in this study to identify various land uses and vegetation types, including remaining patches of primary forest, cabruca forest (cacao planted in the understory of the native forest), secondary forest, pasture and coastal mangrove. Standard remote-sensing technology that relies on light reflected from the forest canopy cannot accurately distinguish between cabruca and undisturbed forest. Optical remote sensing is also

  1. Space radar image of Mount Everest

    NASA Technical Reports Server (NTRS)

    1995-01-01

    These are two comparison images of Mount Everest and its surroundings, along the border of Nepal and Tibet. The peak of Mount Everest, the highest elevation on Earth at 8,848 meters (29,028 feet), can be seen near the center of each image. The image at the top was acquired through thick cloud cover by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on April 16, 1994. The image on the bottom is an optical photograph taken by the Endeavour crew under clear conditions during the second flight of SIR-C/X-SAR on October 10, 1994. Both images show an area approximately 70 kilometers by 38 kilometers (43 miles by 24 miles) that is centered at 28.0 degrees north latitude and 86.9 degrees east longitude. North is toward the upper left. The colors in the radar image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted and vertically received); blue represents the C-band (horizontally transmitted and vertically received). Radar illumination is from the top of the frame. The optical photograph has been geometrically adjusted to better match the area shown in the radar image. Many features of the Himalayan terrain are visible in both images. Snow covered areas appear white in the optical photograph while the same areas appear bright blue in the radar image. The radar image was taken in early spring and shows deep snow cover, while the optical photograph was taken in late summer and shows minimum snow cover. The curving and branching features seen in both images are glaciers. The two wavelengths and multiple polarizations of the SIR-C radar are sensitive to characteristics of the glacier surfaces that are not detected by conventional photography, such as the ice roughness, water content and stratification. For this reason, the glaciers show a variety of colors in the radar image (blue, purple, red

  2. Higher order nonlinear chirp scaling algorithm for medium Earth orbit synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Wang, Pengbo; Liu, Wei; Chen, Jie; Yang, Wei; Han, Yu

    2015-01-01

    Due to the larger orbital arc and longer synthetic aperture time in medium Earth orbit (MEO) synthetic aperture radar (SAR), it is difficult for conventional SAR imaging algorithms to achieve a good imaging result. An improved higher order nonlinear chirp scaling (NLCS) algorithm is presented for MEO SAR imaging. First, the point target spectrum of the modified equivalent squint range model-based signal is derived, where a concise expression is obtained by the method of series reversion. Second, the well-known NLCS algorithm is modified according to the new spectrum and an improved algorithm is developed. The range dependence of the two-dimensional point target reference spectrum is removed by improved CS processing, and accurate focusing is realized through range-matched filter and range-dependent azimuth-matched filter. Simulations are performed to validate the presented algorithm.

  3. Space Radar Image of San Francisco, California

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a radar image of San Francisco, California, taken on October 3,1994. The image is about 40 kilometers by 55 kilometers (25 miles by 34 miles) with north toward the upper right. Downtown San Francisco is visible in the center of the image with the city of Oakland east (to the right) across San Francisco Bay. Also visible in the image is the Golden Gate Bridge (left center) and the Bay Bridge connecting San Francisco and Oakland. North of the Bay Bridge is Treasure Island. Alcatraz Island appears as a small dot northwest of Treasure Island. This image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on orbit 56. The image is centered at 37 degrees north latitude, 122degrees west longitude. This single-frequency SIR-C image was obtained by the L-band (24 cm) radar channel, horizontally transmitted and received. Portions of the Pacific Ocean visible in this image appear very dark as do other smooth surfaces such as airport runways. Suburban areas, with the low-density housing and tree-lined streets that are typical of San Francisco, appear as lighter gray. Areas with high-rise buildings, such as those seen in the downtown areas, appear in very bright white, showing a higher density of housing and streets which run parallel to the radar flight track. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: the L-band (24 cm), C-band (6 cm) and X-band (3cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes

  4. Generation of topographic terrain models utilizing synthetic aperture radar and surface level data

    NASA Technical Reports Server (NTRS)

    Imhoff, Marc L. (Inventor)

    1991-01-01

    Topographical terrain models are generated by digitally delineating the boundary of the region under investigation from the data obtained from an airborne synthetic aperture radar image and surface elevation data concurrently acquired either from an airborne instrument or at ground level. A set of coregistered boundary maps thus generated are then digitally combined in three dimensional space with the acquired surface elevation data by means of image processing software stored in a digital computer. The method is particularly applicable for generating terrain models of flooded regions covered entirely or in part by foliage.

  5. Towards a Semantic Interpretation of Urban Areas with Airborne Synthetic Aperture Radar Tomography

    NASA Astrophysics Data System (ADS)

    D'Hondt, O.; Guillaso, S.; Hellwich, O.

    2016-06-01

    In this paper, we introduce a method to detect and reconstruct building parts from tomographic Synthetic Aperture Radar (SAR) airborne data. Our approach extends recent works in two ways: first, the radiometric information is used to guide the extraction of geometric primitives. Second, building facades and roofs are extracted thanks to geometric classification rules. We demonstrate our method on a 3 image L-Band airborne dataset over the city of Dresden, Germany. Experiments show how our technique allows to use the complementarity between the radiometric image and the tomographic point cloud to extract buildings parts in challenging situations.

  6. A digital system to produce imagery from SAR data. [Synthetic Aperture Radar

    NASA Technical Reports Server (NTRS)

    Wu, C.

    1976-01-01

    This paper describes a digital processing algorithm and its associated system design for producing images from Synthetic Aperture Radar (SAR) data. The proposed system uses the Fast Fourier Transform (FFT) approach to perform the two-dimensional correlation process. The range migration problem, which is often a major obstacle to efficient processing, can be alleviated by approximating the locus of echoes from a point target by several linear segments. SAR data corresponding to each segment is correlated separately, and the results are coherently summed to produce full-resolution images. This processing approach exhibits greatly improved computation efficiency relative to conventional digital processing methods.

  7. Space Radar Image of Dnieper River, Ukraine

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This spaceborne radar image shows the intensive agricultural development in central Ukraine, along the Dnieper River. The area shown lies about 320 kilometers (198 miles) southeast of Kiev and about 360 kilometers (223 miles) northeast of Odessa. Central Ukraine is a rich agricultural region, producing primarily wheat and other grains. In this radar image taken in the early spring, most of the fields do not have active crops, so their relatively smooth texture results in dark shades of brown and purple. Boundaries between the fields consist of hedges or trees which appear as bright outlines. The bright yellowish areas along the river are riparian (riverbank) forest. The small tributary that flows into the Dnieper from the right side of the image is the Volch'ya River. Radar images can be used to map crop types, to monitor the health of crops, and to predict yields. This image was acquired by Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on April 15, 1994. The image is 45 kilometers by 35 kilometers (28 miles by 22 miles) and is centered at 49.0 degrees North latitude, 34.1 degrees East longitude. North is toward the upper right. The colors are assigned to different radar frequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted and received; green is L-band, horizontally transmitted, vertically received; and blue is C-band, horizontally transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian, and United States space agencies, is part of NASA's Mission to Planet Earth.

  8. Space Radar Image of Wenatchee, Washington

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This spaceborne radar image shows a segment of the Columbia River as it passes through the area of Wenatchee, Washington, about 220 kilometers (136 miles) east of Seattle. The Wenatchee Mountains, part of the Cascade Range, are shown in green at the lower left of the image. The Cascades create a 'rain shadow' for the region, limiting rainfall east of the range to less than 26 centimeters (10 inches) per year. The radar's ability to see different types of vegetation is highlighted in the contrast between the pine forests, that appear in green and the dry valley plain that shows up as dark purple. The cities of Wenatchee and East Wenatchee are the grid-like areas straddling the Columbia River in the left center of the image. With a population of about 60,000, the region produces about half of Washington state's lucrative apple crop. Several orchard areas appear as green rectangular patches to the right of the river in the lower right center. Radar images such as these can be used to monitor land use patterns in areas such as Wenatchee, that have diverse and rapidly changing urban, agricultural and wild land pressures. This image was acquired by Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on October 10, 1994. The image is 38 kilometers by 45 kilometers (24 miles by 30 miles) and is centered at 47.3 degrees North latitude, 120.1 degrees West longitude. North is toward the upper left. The colors are assigned to different radar frequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted and received; green is L-band, horizontally transmitted, vertically received; and blue is C-band, horizontally transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian, and United States space agencies, is part of NASA's Mission to Planet Earth.

  9. Space Radar Image of Central Sumatra, Indonesia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a radar image of the central part of the island of Sumatra in Indonesia that shows how the tropical rainforest typical of this country is being impacted by human activity. Native forest appears in green in this image, while prominent pink areas represent places where the native forest has been cleared. The large rectangular areas have been cleared for palm oil plantations. The bright pink zones are areas that have been cleared since 1989, while the dark pink zones are areas that were cleared before 1989. These radar data were processed as part of an effort to assist oil and gas companies working in the area to assess the environmental impact of both their drilling operations and the activities of the local population. Radar images are useful in these areas because heavy cloud cover and the persistent smoke and haze associated with deforestation have prevented usable visible-light imagery from being acquired since 1989. The dark shapes in the upper right (northeast) corner of the image are a chain of lakes in flat coastal marshes. This image was acquired in October 1994 by the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour. Environmental changes can be easily documented by comparing this image with visible-light data that were acquired in previous years by the Landsat satellite. The image is centered at 0.9 degrees north latitude and 101.3 degrees east longitude. The area shown is 50 kilometers by 100 kilometers (31 miles by 62 miles). The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band horizontally transmitted, horizontally received; green is L-band horizontally transmitted, vertically received; blue is L-band vertically transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

  10. SAR image formation using phase-history data from nonuniform aperture

    NASA Astrophysics Data System (ADS)

    Nguyen, Lam; Sichina, Jeffrey

    2007-04-01

    Synthetic aperture radar (SAR) imagery is formed using radar data collected from a moving platform (aircraft, vehicle, human, etc.). The radar transmits and receives backscatter signals in the down-range direction at a fixed pulse repetition interval (PRI) while the platform moves along the cross-range direction (called along-track) to generate a synthetic aperture. In the ideal situation, the platform moves at a constant speed and as a result, the radar will collect the phase-history data that are uniformly sampled along the aperture. However, in many situations the radar platform cannot be kept at a constant speed, e.g. a helicopter maneuvering over an imaging area for surveillance. The problem is even worse in the case of urban warfare with human-borne radar. A soldier moves at his own speed and creates erratic aperture sections with phase-history data that are either sparse or dense. The collected SAR data in such situation will result in SAR imagery with severe artifacts that might prevent us from detecting targets of interest. In this paper, we will present the SAR imagery of non-uniform aperture data formed using the backprojection image formation algorithm. Although the backprojection image former is well suited to an arbitrary radar aperture, the SAR image artifacts are obvious from the nonuniform aperture. Using the nonuniform aperture phase-history data, we interpolate the data using a uniform grid along the aperture. We will show the resulting imagery with reduced artifacts. We use both simulated data and the Army Research Lab BoomSAR data to illustrate the artifacts generated by nonuniform sampling and the improvement using this interpolation technique.

  11. Space Radar Image of Eastern Morocco

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This spaceborne radar image shows how the Atlas Mountains in northwestern Africa dominate the geography of Morocco. The image shows a part of the eastern flank of these mountains near the town of Rissani, approximately 50 kilometers (31 miles) from its border with Algeria. The striking bright patterns are the complex folds in the layered rocks of this region. Careful examination of the image shows areas where the folded structures have been disrupted due to fault movement and earthquakes. Dark areas between the rock outcrops are covered in sand and serve as channels for seasonal streams in this arid region. Scientists can use images like this one to map the geology and drainage patterns in arid regions. The area shown is 44 kilometers by 34 kilometers (27 miles by 21 miles)centered at 31 degrees north latitude, 4.4 degrees west longitude; north is toward the upper right. Colors are assigned to different radar frequencies and polarizations as follows: red is L-band horizontally transmitted, horizontally received; green is C-band horizontally transmitted, horizontally received; blue is C-band horizontally transmitted, vertically received. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture (SIR-C/X-SAR) imaging radar when it flew aboard the space shuttle Endeavour on April 15, 1994. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

  12. Space Radar Image of Ventura County, California

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This radar image of Ventura County, California, shows the Santa Clara River valley and the surrounding mountains. The river valley is the linear feature that extends from the lower right to the upper left (east to west), where it empties into the Pacific Ocean (dark patches in upper and lower left). The cities of Ventura and Oxnard are seen along the left side of the image. Simi Valley is located in the lower center of the image, between the Santa Monica Mountains (purple area in lower left) and the Santa Susanna Mountains to the north. This area of California is known for its fruit; strawberry fields are shown in red and purple rectangular areas on the coastal plain, and citrus groves are the yellow green areas adjacent to the river. This image is centered at 34.33 degrees north latitude, 119 degrees west longitude. The area shown is approximately 53 kilometers by 35 kilometers (33 miles by 22 miles). Colors are assigned to different radar frequencies and polarizations as follows: red is L-band, horizontally transmitted, horizontally received; green is L-band, horizontally transmitted, vertically received; blue is C-band, horizontally transmitted, vertically received. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture (SIR-C/X-SAR) imaging radar when it flew aboard the space shuttle Endeavour on October 6, 1994.

  13. Performance limits for maritime Inverse Synthetic Aperture Radar (ISAR).

    SciTech Connect

    Doerry, Armin Walter

    2013-11-01

    The performance of an Inverse Synthetic Aperture Radar (ISAR) system depends on a variety of factors, many which are interdependent in some manner. In this report we specifically examine ISAR as applied to maritime targets (e.g. ships). It is often difficult to get your arms around' the problem of ascertaining achievable performance limits, and yet those limits exist and are dictated by physics. This report identifies and explores those limits, and how they depend on hardware system parameters and environmental conditions. Ultimately, this leads to a characterization of parameters that offer optimum performance for the overall ISAR system. While the information herein is not new to the literature, its collection into a single report hopes to offer some value in reducing the seek time'.

  14. The Rapid Terrain Visualization interferometric synthetic aperture radar sensor.

    SciTech Connect

    Graham, Robert H.; Hensley, William Heydon, Jr.; Bickel, Douglas Lloyd

    2003-07-01

    The Rapid Terrain Visualization interferometric synthetic aperture radar was designed and built at Sandia National Laboratories as part of an Advanced Concept Technology Demonstration (ACTD) to 'demonstrate the technologies and infrastructure to meet the Army requirement for rapid generation of digital topographic data to support emerging crisis or contingencies.' This sensor is currently being operated by Sandia National Laboratories for the Joint Precision Strike Demonstration (JPSD) Project Office to provide highly accurate digital elevation models (DEMs) for military and civilian customers, both inside and outside of the United States. The sensor achieves better than DTED Level IV position accuracy in near real-time. The system is being flown on a deHavilland DHC-7 Army aircraft. This paper outlines some of the technologies used in the design of the system, discusses the performance, and will discuss operational issues. In addition, we will show results from recent flight tests, including high accuracy maps taken of the San Diego area.

  15. Seamless Synthetic Aperture Radar Archive for Interferometry Analysis

    NASA Astrophysics Data System (ADS)

    Baker, S.; Baru, C.; Bryson, G.; Buechler, B.; Crosby, C.; Fielding, E.; Meertens, C.; Nicoll, J.; Youn, C.

    2014-11-01

    The NASA Advancing Collaborative Connections for Earth System Science (ACCESS) seamless synthetic aperture radar (SAR) archive (SSARA) project is a collaboration between UNAVCO, the Alaska Satellite Facility (ASF), the Jet Propulsion Laboratory (JPL), and OpenTopography at the San Diego Supercomputer Center (SDSC) to design and implement a seamless distributed access system for SAR data and derived interferometric SAR (InSAR) data products. A unified application programming interface (API) has been created to search the SAR archives at ASF and UNAVCO, 30 and 90-m SRTM DEM data available through OpenTopography, and tropospheric data from the NASA OSCAR project at JPL. The federated query service provides users a single access point to search for SAR granules, InSAR pairs, and corresponding DEM and tropospheric data products from the four archives, as well as the ability to search and download pre-processed InSAR products from ASF and UNAVCO.

  16. Moving receive beam method and apparatus for synthetic aperture radar

    DOEpatents

    Kare, Jordin T.

    2001-01-01

    A method and apparatus for improving the performance of Synthetic Aperture Radar (SAR) systems by reducing the effect of "edge losses" associated with nonuniform receiver antenna gain. By moving the receiver antenna pattern in synchrony with the apparent motion of the transmitted pulse along the ground, the maximum available receiver antenna gain can be used at all times. Also, the receiver antenna gain for range-ambiguous return signals may be reduced, in some cases, by a large factor. The beam motion can be implemented by real-time adjustment of phase shifters in an electronically-steered phased-array antenna or by electronic switching of feed horns in a reflector antenna system.

  17. Theory and design of interferometric synthetic aperture radars

    NASA Technical Reports Server (NTRS)

    Rodriguez, E.; Martin, J. M.

    1992-01-01

    A derivation of the signal statistics, an optimal estimator of the interferometric phase, and the expression necessary to calculate the height-error budget are presented. These expressions are used to derive methods of optimizing the parameters of the interferometric synthetic aperture radar system (InSAR), and are then employed in a specific design example for a system to perform high-resolution global topographic mapping with a one-year mission lifetime, subject to current technological constraints. A Monte Carlo simulation of this InSAR system is performed to evaluate its performance for realistic topography. The results indicate that this system has the potential to satisfy the stringent accuracy and resolution requirements for geophysical use of global topographic data.

  18. An algorithm to retrieve precipitation with synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Xie, Ya'nan; Liu, Zhikun; An, Dawei

    2016-06-01

    This paper presents a new type of rainfall retrieval algorithm, called the model-oriented statistical and Volterra integration. It is a combination of the model-oriented statistical (MOS) and Volterra integral equation (VIE) approaches. The steps involved in this new algorithm can be briefly illustrated as follows. Firstly, information such as the start point and width of the rain is obtained through pre-analysis of the data received by synthetic aperture radar (SAR). Secondly, the VIE retrieval algorithm is employed over a short distance to obtain information on the shape of the rain. Finally, the rain rate can be calculated by using the MOS retrieval algorithm. Simulation results show that the proposed algorithm is effective and simple, and can lead to time savings of nearly 50% compared with MOS. An example of application of SAR data is also discussed, involving the retrieval of precipitation information over the South China Sea.

  19. Wideband electromagnetic scattering program. Fourier-based radar imaging techniques

    NASA Astrophysics Data System (ADS)

    Chan, B. L.; Young, J. D.; Rudduck, R. C.

    1993-09-01

    This report describes the implementation of Fourier based radar imaging algorithms in a computer program. In particular, the algorithms are derived for wide bandwidth and for specific geometries. These geometries are often measured by radar cross section measurement systems such as compact ranges and near field linear synthetic aperture radar systems. The limitations of different implementations of the algorithms are presented. Imaging results from radar measurements are also presented for an F-4 fighter aircraft, an M35 truck (1/16 scale model), and a forest.

  20. Forest discrimination with multipolarization imaging radar

    NASA Technical Reports Server (NTRS)

    Ford, J. P.; Wickland, D. E.

    1985-01-01

    The use of radar polarization diversity for discriminating forest canopy variables on airborne synthetic-aperture radar (SAR) images is evaluated. SAR images were acquired at L-Band (24.6 cm) simultaneously in four linear polarization states (HH, HV, VH, and VV) in South Carolina on March 1, 1984. In order to relate the polarization signatures to biophysical properties, false-color composite images were compared to maps of forest stands in the timber compartment. In decreasing order, the most useful correlative forest data are stand basal area, forest age, site condition index, and forest management type. It is found that multipolarization images discriminate variation in tree density and difference in the amount of understory, but do not discriminate between evergreen and deciduous forest types.

  1. Radar Imaging of Asteroids

    NASA Astrophysics Data System (ADS)

    Ostro, S. J.

    1996-09-01

    Measurements of the distribution of echo power in time delay (range) and Doppler frequency (line-of-sight velocity) can synthesize images of near-Earth and main-belt asteroids (NEAs and MBAs) that traverse the detectability windows of groundbased radar telescopes. Under ideal circumstances, current radar waveforms can achieve decameter surface resolution. The number of useful pixels obtainable in an imaging data set is of the same order as the signal-to-noise ratio, SNR, of an optimally filtered, weighted sum of all the data. (SNR increases as the square root of the integration time.) The upgraded Arecibo telescope which is about to become operational, should be able to achieve single-date SNRs {\\underline>} (20,100) for an average of (35,5) MBAs per year and single-date SNRs {\\underline>} (20,100,1000) for an average of (10,6,2) of the currently catalogued NEAs per year; optical surveying of the NEA population could increase the frequency of opportunities by an order of magnitude. The strongest imaging opportunities predicted for Arecibo between now and the end of 1997 include (the peak SNR/date is in parentheses): 9 Metis (110), 27 Euterpe (170), 80 Sappho (100), 139 Juewa (140), 144 Vibilia (140), 253 Mathilde (100), 2102 Tantalus (570), 3671 Dionysus (170), 3908 1980PA (4400), 4179 Toutatis (16000), 4197 1982TA (1200), 1991VK (700), and 1994PC1 (7400). A delay-Doppler image projects the echo power distribution onto the target's apparent equatorial plane. One cannot know a priori whether one or two (or more) points on the asteroid contributed power to a given pixel, so accurate interpretation of delay-Doppler images requires modeling (Hudson, 1993, Remote Sensing Rev. 8, 195-203). Inversion of an imaging sequence with enough orientational coverage can remove "north/south" ambiguities and can provide estimates of the target's three-dimensional shape, spin state, radar scattering properties, and delay-Doppler trajectory (e.g., Ostro et al. 1995, Science 270, 80

  2. Synthetic Aperture Radar Interferometry for Digital Elevation Model of Kuwait Desert - Analysis of Errors

    NASA Astrophysics Data System (ADS)

    Jassar, H. K. Al; Rao, K. S.

    2012-07-01

    Using different combinations of 29 Advanced Synthetic Aperture Radar (ASAR) images, 43 Digital Elevations Models (DEM) were generated adopting SAR Interferometry (InSAR) technique. Due to sand movement in desert terrain, there is a poor phase correlation between different SAR images. Therefore, suitable methodology for generating DEMs of Kuwait desert terrain using InSAR technique were worked out. Time series analysis was adopted to derive the best DEM out of 43 DEMs. The problems related to phase de-correlation over desert terrain are discussed. Various errors associated with the DEM generation are discussed which include atmospheric effects, penetration into soil medium, sand movement. The DEM of Shuttle Radar Topography Mission (SRTM) is used as a reference. The noise levels of DEM of SRTM are presented.

  3. Seasat synthetic aperture radar observations of wave-current and wave-topographic interactions

    NASA Technical Reports Server (NTRS)

    Meadows, G. A.; Tseng, Y. C.; Shuchman, R. A.; Kasischke, E. S.

    1983-01-01

    This study investigated the capability of a spaceborne, imaging radar system to detect subtle changes in the propagation characteristics of ocean wave systems. Specifically, an evolving surface gravity wave system emanating from Hurricane Ella and propagating toward Cape Hatteras, NC, formed the basis of this investigation. This wave system was successfully imaged by the Seasat synthetic aperture radar (SAR) during revolution 974 on September 3, 1978. Estimates of the dominant wavelength and direction of the ocean waves were derived from the SAR data by using optical Fourier transforms. Environmental data of the test area, which included the surface velocity vector within the Gulf Stream, the location of Hurricane Ella, and local bathymetric information, were used in conjunction with the SAR data to form the basis of this comparative study. Favorable agreement was found between wave rays calculated by utilizing theoretical wave-current and wave-topographic interactions and SAR observed dominant wavelength and direction changes across the Gulf Stream and continental shelf.

  4. Space Radar Image of Samara, Russia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This three-frequency space radar image shows the city of Samara, Russia in pink and light green right of center. Samara is at the junction of the Volga and Samara Rivers approximately 800 kilometers (500 miles) southeast of Moscow. The wide river in the center of the image is the Volga. Samara, formerly Kuybyshev, is a busy industrial city known for its chemical, mechanical and petroleum industries. Northwest of the Volga (upper left corner of the image) are deciduous forests of the Samarskaya Luka National Park. Complex patterns in the floodplain of the Volga are caused by 'cut-off' lakes and channels from former courses of the meandering river. The three radar frequencies allow scientists to distinguish different types of agricultural fields in the lower right side of the image. For example, fields which appear light blue are short grass or cleared fields. Purple and green fields contain taller plants or rough plowed soil. Scientists hope to use radar data such as these to understand the environmental consequences of industrial, agricultural and natural preserve areas coexisting in close proximity. This image is 50 kilometers by 26 kilometers (31 by 16 miles) and is centered at 53.2 degrees north latitude, 50.1 degrees east longitude. North is toward the top of the image. The colors are assigned to different radar frequencies and polarizations as follows: red is L-band, horizontally transmitted and received; green is C-band, horizontally transmitted and vertically received; and blue is X-band, vertically transmitted and received. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) on October 1, 1994 onboard the space shuttle Endeavour. SIR-C/X-SAR, a joint mission of the German, Italian and the United States space agencies, is part of NASA's Mission to Planet Earth.

  5. Space Radar Image of Mineral Resources, China

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This spaceborne radar image of a mineral-rich region in southern China is being used by geologists to identify potential new areas for mineral exploration. The area shown is the vicinity of the city of Zhao Qing, the light blue area along the banks of the River Xi Jiang in the lower left. This is in the southern Chinese province of Guangdong, about 75 kilometers (46 miles) west of Guangzhou (Canton). The largest gold mine in southern China is located in the far upper left of the image along a brightly reflective mountain ridge. Using the radar image as a guide, geologists are tracing the extension of the ridge structure to the east (right) to identify possible mining areas. Radar imaging is especially useful for this purpose because of its sensitivity to subtle topographic structure, even in areas such as these, which have a dense vegetation cover. The Xi Jiang area is one of the most productive mining regions in China, with deposits of tungsten, lead, zinc and gold. The image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttleEndeavour on April 17, 1994. The image is centered at 37.2 degreesnorth latitude and 112.5 degrees east longitude. North is toward the upper right. The image shows an area 60 kilometers by 38 kilometers (37.2 miles by 23.6 miles) The colors are assigned to different frequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted, horizontally received; green is L-band, horizontally transmitted, vertically received; blue is C-band, horizontally transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earthprogram.

  6. Target detection beneath foliage using polarimetric synthetic aperture radar interferometry

    NASA Astrophysics Data System (ADS)

    Cloude, S. R.; Corr, D. G.; Williams, M. L.

    2004-04-01

    In this paper, we demonstrate how the new technology of polarimetric synthetic aperture radar (SAR) interferometry can be used to enhance the detection of targets hidden beneath foliage. The key idea is to note that for random volume scattering, the interferometric coherence is invariant to changes in wave polarization. On the other hand, in the presence of a target the coherence changes with polarization. We show that under general symmetry constraints this change is linear in the complex coherence plane. These observations can be used to devise a filter to suppress the returns from foliage clutter while maintaining the signal from hidden targets. We illustrate the algorithm by applying it to coherent L-band SAR simulations of corner reflectors hidden in a forest. The simulations are performed using a voxel-based vector wave propagation and scattering code coupled to detailed structural models of tree architecture. In this way, the spatial statistics and radar signal fluctuations closely match those observed for natural terrain. We demonstrate significant improvements in the detection of hidden targets, which suggests that this technology has great potential for future foliage penetration (FOPEN) applications.

  7. Space Radar Image of Athens, Greece

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This space radar image of Athens, Greece, shows the sprawling, modern development of this ancient capital city. Densely populated urban areas appear in shades of pink and light green. The Acropolis the dark green triangular patch in the center of the image. Archaeological discoveries indicate Athens has been continuously occupied for at least the last 5,000 years. Numerous ships, shown as bright dots, are seen in the harbor areas in the upper left part of the image. The port city of Piraeus is at the left center. This image is 45 kilometers by 45 kilometers (28 miles by 28 miles) and is centered at 37.9 degrees north latitude, 23.7 degrees east longitude. North is toward the upper right. The colors are assigned to different radar frequencies and polarizations are as follows: red is L-band, horizontally transmitted and received; green is L-band, horizontally transmitted and vertically received; and blue is C-band, horizontally transmitted and received. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) on October 2, 1994 onboard the space shuttle Endeavour. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

  8. Space Radar Image of North Atlantic Ocean

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a radar image showing surface features on the open ocean in the northeast Atlantic Ocean. There is no land mass in this image. The purple line in the lower left of the image is the stern wake of a ship. The ship creating the wake is the bright white spot on the middle, left side of the image. The ship's wake is about 28 kilometers (17 miles) long in this image and investigators believe that is because the ship may be discharging oil. The oil makes the wake last longer and causes it to stand out in this radar image. A fairly sharp boundary or front extends from the lower left to the upper right corner of the image and separates two distinct water masses that have different temperatures. The different water temperature affects the wind patterns on the ocean. In this image, the light green area depicts rougher water with more wind, while the purple area is calmer water with less wind. The dark patches are smooth areas of low wind, probably related to clouds along the front, and the bright green patches are likely due to ice crystals in the clouds that scatter the radar waves. The overall 'fuzzy' look of this image is caused by long ocean waves, also called swells. Ocean radar imagery allows the fine detail of ocean features and interactions to be seen, such as the wake, swell, ocean front and cloud effects, which can then be used to enhance the understanding of ocean dynamics on smaller and smaller scales. The image is centered at 42.8 degrees north latitude, 26.2 degrees west longitude and shows an area approximately 35 kilometers by 65 kilometers (22 by 40 miles). The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band horizontally transmitted, horizontally received; green is C-band horizontally transmitted, horizontally received; blue is L-band vertically transmitted, vertically received. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR

  9. Space radar image of New York City

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This radar image of the New York city metropolitan area. The island of Manhattan appears in the center of the image. The green-colored rectangle on Manhattan is Central Park. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/ X-SAR) aboard the space shuttle Endeavour on October 10, 1994. North is toward the upper right. The area shown is 75.0 kilometers by 48.8 kilometers (46.5 miles by 30.2 miles). The image is centered at 40.7 degrees north latitude and 73.8 degrees west longitude. In general, light blue areas correspond to dense urban development, green areas to moderately vegetated zones and black areas to bodies of water. The Hudson River is the black strip that runs from the left edge to the upper right corner of the image. It separates New Jersey, in the upper left of the image, from New York. The Atlantic Ocean is at the bottom of the image where two barrier islands along the southern shore of Long Island are also visible. John F. Kennedy International Airport is visible above these islands. Long Island Sound, separating Long Island from Connecticut, is the dark area right of the center of the image. Many bridges are visible in the image, including the Verrazano Narrows, George Washington and Brooklyn bridges. The radar illumination is from the left of the image; this causes some urban zones to appear red because the streets are at a perpendicular angle to the radar pulse. The colors in this image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted, vertically received); blue represents the C-band (horizontally transmitted, vertically received). Radar images like this one could be used as a tool for city planners and resource managers to map and monitor land use patterns. The radar imaging systems can clearly detect the variety of landscapes in the area, as well as the density of urban

  10. Unexploded ordnance detection experiments using ultrawideband synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    DeLuca, Clyde C.; Marinelli, Vincent R.; Ressler, Marc A.; Ton, Tuan T.

    1998-09-01

    The Army Research Laboratory (ARL) has several technology development programs that are evaluating the use of ultra- wideband synthetic aperture radar (UWB SAR) to detect and locate targets that are subsurface or concealed by foliage. Under these programs, a 1-GHz-bandwidth, low-frequency, fully polarimetric UWB SAR instrumentation system was developed to collect the data needed to support foliage and ground- penetrating radar studies. The radar was integrated onto a 150-ft-high mobile boomlift platform in 1995 and was thus named the BoomSAR. In 1997, under the sponsorship of the Strategic Environmental Research and Development Program (SERDP), ARL began a project focused on enhancing the detection and discrimination of unexploded ordnance (UXO). The program's technical approach is to collect high-quality, precision data to support phenomenological investigations of electromagnetic wave propagation through varying dielectric media, which in turn supports the development of algorithms for automatic target detection. For this project, a UXO test site was set up at the Steel Crater Test Area -- an existing test site that already contained subsurface mines, tactical vehicles, 55-gallon drums, storage containers, wires, pipes, and arms caches located at Yuma Proving Ground (YPG), Arizona. More than 600 additional pieces of inert UXO were added to the Steel Crater Test Area, including bombs (250, 500, 750, 1000, and 2000 lb), mortars (60 and 81 mm), artillery shells (105 and 155 mm), 2.75-in. rockets, submunitions (M42, BLU-63, M68, BLU-97, and M118), and mines (Gator, VS1.6, M12, PMN, and POM- Z). In the selection of UXO to be included at YPG, an emphasis was placed on the types of munitions that may be present at CONUS test and training ranges.

  11. Space Radar Image of Manaus, Brazil

    NASA Technical Reports Server (NTRS)

    1999-01-01

    These two images were created using data from the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR). On the left is a false-color image of Manaus, Brazil acquired April 12, 1994, onboard space shuttle Endeavour. In the center of this image is the Solimoes River just west of Manaus before it combines with the Rio Negro to form the Amazon River. The scene is around 8 by 8 kilometers (5 by 5 miles) with north toward the top. The radar image was produced in L-band where red areas correspond to high backscatter at HH polarization, while green areas exhibit high backscatter at HV polarization. Blue areas show low backscatter at VV polarization. The image on the right is a classification map showing the extent of flooding beneath the forest canopy. The classification map was developed by SIR-C/X-SAR science team members at the University of California,Santa Barbara. The map uses the L-HH, L-HV, and L-VV images to classify the radar image into six categories: Red flooded forest Green unflooded tropical rain forest Blue open water, Amazon river Yellow unflooded fields, some floating grasses Gray flooded shrubs Black floating and flooded grasses Data like these help scientists evaluate flood damage on a global scale. Floods are highly episodic and much of the area inundated is often tree-covered. Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those

  12. Space Radar Image of Los Angeles, California

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a radar image of Los Angeles, California, taken on October 2, 1994. Visible in the image are Long Beach Harbor at the bottom right (south corner of the image), Los Angeles International Airport at the bottom center, with Santa Monica just to the left of it and the Hollywood Hills to the left of Santa Monica. Also visible in the image are the freeway systems of Los Angeles, which appear as dark lines. The San Gabriel Mountains (center top) and the communities of San Fernando Valley, Simi Valley and Palmdale can be seen on the left-hand side. This image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on its 24th orbit. The image is centered at 34 degrees north latitude, 118 degrees west longitude. The area shown is approximately 100 kilometers by 52 kilometers (62 miles by 32 miles). This single-frequency SIR-C image was obtained by the L-band (24 cm) radar channel, horizontally transmitted and received. Portions of the Pacific Ocean visible in this image appear very dark as do freeways and other flat surfaces such as the airport runways. Mountains in the image are dark grey, with brighter patches on the mountain slopes, which face in the direction of the radar illumination (from the top of the image). Suburban areas, with the low-density housing and tree-lined streets that are typical of Los Angeles, appear as lighter grey. Areas with high-rise buildings, such as downtown Los Angeles, appear in very bright white, showing a higher density of housing and streets which run parallel to the radar flight track. Scientists hope to use radar image data from SIR-C/X-SAR to map fire scars in areas prone to brush fires, such as Los Angeles. In this image, the Altadena fire area is visible in the top center of the image as a patch of mountainous terrain which is slightly darker than the nearby mountains. Using all the radar frequency and polarization images provided by SIR

  13. Space Radar Image of Kilauea, Hawaii

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Data acquired on April 13, 1994 and on October 4, 1994 from the X-band Synthetic Aperture Radar on board the space shuttle Endeavour were used to generate interferometric fringes, which were overlaid on the X-SAR image of Kilauea. The volcano is centered in this image at 19.58 degrees north latitude and 155.55 degrees west longitude. The image covers about 9 kilometers by 13 kilometers (5.6 miles by 8 miles). The X-band fringes correspond clearly to the expected topographic image. The yellow line indicates the area below which was used for the three-dimensional image using altitude lines. The yellow rectangular frame fences the area for the final topographic image. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI), with the Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.V.(DLR), the major partner in science, operations and data processing of X-SAR. The Instituto Ricerca Elettromagnetismo Componenti Elettronici (IRECE) at the University of Naples was a partner in interferometry analysis.

  14. Fisheries imaging radar surveillance test /FIRST/ - Bering Sea test

    NASA Technical Reports Server (NTRS)

    Woods, E. G.; Ivey, J. H.

    1977-01-01

    A joint NOAA, U.S. Coast Guard and NASA program is being conducted to determine if a synthetic aperture radar (SAR) system, such as planned for NASA's SEASAT, can be useful in monitoring fishing vessels within the newly established 200-mile fishing limit. As part of this program, data gathering field operations were conducted over concentrations of foreign fishing vessels in the Bering Sea off Alaska in April 1976. The Jet Propulsion Laboratory developed synthetic aperture L-band radar which was flown aboard the NASA Convair 990 aircraft, with a Coast Guard cutter and C-130 aircraft simultaneously gathering data to provide both radar imagery and sea truth information on the vessels being imaged. Results indicate that synthetic aperture radar systems have potential for all weather detection, enumeration and classification of fishing vessels.

  15. Beam Width Robustness of a 670 GHz Imaging Radar

    NASA Technical Reports Server (NTRS)

    Cooper, K. B.; Llombart, N.; Dengler, R. J.; Siegel, P. H.

    2009-01-01

    Detection of a replica bomb belt concealed on a mannequin at 4 m standoff range is achieved using a 670 GHz imaging radar. At a somewhat larger standoff range of 4.6 m, the radar's beam width increases substantially, but the through-shirt image quality remains good. This suggests that a relatively modest increase in aperture size over the current design will be sufficient to detect person-borne concealed weapons at ranges exceeding 25 meters.

  16. Simulation of noise involved in synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Grandchamp, Myriam; Cavassilas, Jean-Francois

    1996-08-01

    The synthetic aperture radr (SAR) returns from a linear distribution of scatterers are simulated and processed in order to estimate the reflectivity coefficients of the ground. An original expression of this estimate is given, which establishes the relation between the terms of signal and noise. Both are compared. One application of this formulation consists of detecting a surface ship wake on a complex SAR image. A smoothing is first accomplished on the complex image. The choice of the integration area is determined by the preceding mathematical formulation. Then a differential filter is applied, and results are shown for two parts of the wake.

  17. Space Radar Image of La Paz, Bolivia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is an image of the Bolivian capital city of La Paz that was created using three radar frequencies. La Paz sits at the edge of the Altiplano, the high inland plateau between the Cordillera Occidental and Cordillera Oriental belts of the Andes Mountains in South America. Part of the Cordillera Oriental mountains are seen on the right side (northeast) of this image. The bright areas at the top of the mountains are most likely the result of year-round snow cover. Glacier-carved valleys drain the mountain areas. The dark lines left of center are Kennedy Airport near the northwestern part of the city. The image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on April 18, 1994. The image is centered at 16.25 degrees south latitude, 68.1 degrees west longitude. The area shown is approximately 35 kilometers by 16 kilometers (22 miles by 10 miles). North is toward the upper right. Colors are assigned to different frequencies and polarizations of the radar as follows: red is L-band horizontally transmitted, horizontally received; green is C-band horizontally transmitted, vertically received; and blue is X-band vertically transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's program called Mission to Planet Earth.

  18. Correction of motion measurement errors beyond the range resolution of a synthetic aperture radar

    SciTech Connect

    Doerry, Armin W.; Heard, Freddie E.; Cordaro, J. Thomas

    2008-06-24

    Motion measurement errors that extend beyond the range resolution of a synthetic aperture radar (SAR) can be corrected by effectively decreasing the range resolution of the SAR in order to permit measurement of the error. Range profiles can be compared across the slow-time dimension of the input data in order to estimate the error. Once the error has been determined, appropriate frequency and phase correction can be applied to the uncompressed input data, after which range and azimuth compression can be performed to produce a desired SAR image.

  19. Imaging radar observations of frozen Arctic lakes

    NASA Technical Reports Server (NTRS)

    Elachi, C.; Bryan, M. L.; Weeks, W. F.

    1976-01-01

    A synthetic aperture imaging L-band radar flown aboard the NASA CV-990 remotely sensed a number of ice-covered lakes about 48 km northwest of Bethel, Alaska. The image obtained is a high resolution, two-dimensional representation of the surface backscatter cross section, and large differences in backscatter returns are observed: homogeneous low returns, homogeneous high returns and/or low returns near lake borders, and high returns from central areas. It is suggested that a low return indicates that the lake is frozen completely to the bottom, while a high return indicates the presence of fresh water between the ice cover and the lake bed.

  20. Space Radar Image of Boston, Massachusetts

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This radar image of the area surrounding Boston, Mass., shows how a spaceborne radar system distinguishes between densely populated urban areas and nearby areas that are relatively unsettled. The bright white area at the right center of the image is downtown Boston. The wide river below and to the left of the city is the Charles River in Boston's Back Bay neighborhood. The dark green patch to the right of the Back Bay is Boston Common. A bridge across the north end of Back Bay connects the cities of Boston and Cambridge. The light green areas that dominate most of the image are the suburban communities surrounding Boston. The many ponds that dot the region appear as dark irregular spots. Many densely populated urban areas show up as red in the image due to the alignment of streets and buildings to the incoming radar beam. North is toward the upper left. The image was acquired on October 9, 1994, by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) as it flew aboard the space shuttle Endeavour. This area is centered at 42.4 degrees north latitude, 71.2 degrees west longitude. The area shown is approximately 37 km by 18 km (23 miles by 11 miles). Colors are assigned to different radar frequencies and polarizations as follows: red is L-band horizontally transmitted, horizontally received; green is L-band horizontally transmitted, vertically received; blue is C-band horizontally transmitted, vertically received. SIR-C/X-SAR, a cooperative mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

  1. Space Radar Image of Hampton Roads, Virginia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This radar image shows the Hampton Roads, Virginia region, where the James River (upper left center) flows into the Chesapeake Bay. The city of Norfolk is the bright area on the peninsula in the lower center. Norfolk is home to a large naval base, part of which can be seen as the bright white port facilities near the center of the image. The cities of Hampton and Newport News occupy the peninsula in the upper right of the image. The dark blue areas on this peninsula are the runways of Langley Air Force Base, which also houses NASA's Langley Research Center. Forested areas, including suburbs, appear as green on the image. Cities appear as green, white and orange. The purple areas along the shorelines are wetlands; blue areas are cleared for agricultural use. Faint ship wakes can be seen in the water behind ships entering and leaving Hampton Roads. Scientists are using radar images like this one to study delicate coastal environments and the effects of urbanization and other human activities on the ecosystem and landscape. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture (SIR-C/X-SAR) imaging radar when it flew aboard the space shuttle Endeavour on October 5, 1994. The image is centered at 36.9 degrees north latitude, 76.4 degrees west longitude. North is towards the upper right. The area shown is 37 kilometers by 29 kilometers (23 miles by 18 miles). Colors are assigned to different frequencies and polarizations of the radar as follows: red is L-band horizontally transmitted, horizontally received; green is L-band horizontally transmitted, vertically received; blue is C-band horizontally transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's ongoing Mission to Planet Earth program.

  2. Space Radar Image of Safsaf Oasis, Egypt

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This three-frequency space radar image of south-central Egypt demonstrates the unique capability of imaging radar to penetrate thin sand cover in arid regions to reveal hidden details below the surface. Nearly all of the structures seen in this image are invisible to the naked eye and to conventional optical satellite sensors. Features appear in various colors because the three separate radar wavelengths are able to penetrate the sand to different depths. Areas that appear red or orange are places that can be seen only by the longest wavelength, L-band, and they are the deepest of the buried structures. Field studies in this area indicate L-band can penetrate as much as 2 meters (6.5 feet) of very dry sand to image buried rock structures. Ancient drainage channels at the bottom of the image are filled with sand more than 2 meters (6.5 feet) thick and therefore appear dark because the radar waves cannot penetrate them. The fractured orange areas at the top of the image and the blue circular structures in the center of the image are granitic areas that may contain mineral ore deposits. Scientists are using the penetrating capabilities of radar imaging in desert areas in studies of structural geology, mineral exploration, ancient climates, water resources and archaeology. This image is 51.9 kilometers by 30.2 kilometers (32.2 miles by 18.7 miles) and is centered at 22.7 degrees north latitude, 29.3degrees east longitude. North is toward the upper right. The colors are assigned to different radar frequencies and polarizations as follows: red is L-band, horizontally transmitted and received; green is C-band, horizontally transmitted and received; and blue is X-band, vertically transmitted and received. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) on April 16, 1994, on board the space shuttle Endeavour. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission

  3. Space Radar Image of Saline Valley, California

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a three-dimensional perspective view of Saline Valley, about 30 km (19 miles) east of the town of Independence, California created by combining two spaceborne radar images using a technique known as interferometry. Visualizations like this one are helpful to scientists because they clarify the relationships of the different types of surfaces detected by the radar and the shapes of the topographic features such as mountains and valleys. The view is looking southwest across Saline Valley. The high peaks in the background are the Inyo Mountains, which rise more than 3,000 meters (10,000 feet) above the valley floor. The dark blue patch near the center of the image is an area of sand dunes. The brighter patches to the left of the dunes are the dry, salty lake beds of Saline Valley. The brown and orange areas are deposits of boulders, gravel and sand known as alluvial fans. The image was constructed by overlaying a color composite radar image on top of a digital elevation map. The radar image was taken by the Spaceborne Imaging Radar-C/X-bandSynthetic Aperture Radar (SIR-C/X-SAR) on board the space shuttleEndeavour in October 1994. The digital elevation map was producedusing radar interferometry, a process in which radar data are acquired on different passes of the space shuttle. The two data passes are compared to obtain elevation information. The elevation data were derived from a 1,500-km-long (930-mile) digital topographic map processed at JPL. Radar image data are draped over the topography to provide the color with the following assignments: red is L-band vertically transmitted, vertically received; green is C-band vertically transmitted, vetically received; and blue is the ratio of C-band vertically transmitted, vertically received to L-band vertically transmitted, vertically received. This image is centered near 36.8 degrees north latitude and 117.7 degrees west longitude. No vertical exaggeration factor has been applied to the data. SIR-C/X-SAR, a joint

  4. Footprints of storms on the sea: A view from spaceborne synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Atlas, David

    1994-01-01

    Synthetic aperture radar (SAR) on board Seasat observed images of stormlike echoes on the sea in 1978. The core of these images is usually an echo-free hole which is attributed to the damping of the short (30-cm) radar detectable gravity waves by the intense rain in the storm core. Although 'the beating down of waves by rain' is consistent with observations by seafarers and with the first scientific explanation of the phenomenon by Reynolds (1875), neither theory nor experiment has provided definitive support. One experiment appears to provide the key; it shows that the kenetic energy of the rain produces sufficient turbulence in a thin fresh water layer to damp 30-cm waves in 10-20 s, thus producing the echo-free hole. A sequence of positive feedbacks then serves to damp the longer waves. The angular dependence of the sea surface echo cross sections seen by Seasat SAR outside the echo-free hole indicates winds diverging from the downdraft induced by the intense rain core. The wind-generated waves and associated echoes extend out to a sharply defined gust front. The sea surface footprint thus mimics the features of a storm microburst. The variations in surface radar cross section due to a combination of rain and wind effects impacts spaceborne measurements of surface winds by scatterometry and rainfall measurements by radar. Portions of this synthesis remain speculative but serve as hypotheses for further research.

  5. Synthetic aperture methods for angular scatter imaging

    NASA Astrophysics Data System (ADS)

    Guenther, Drake A.; Ranganathan, Karthik; McAllister, Michael J.; Rigby, K. W.; Walker, William F.

    2004-04-01

    Angular scatter offers a new source of tissue contrast and an opportunity for tissue characterization in ultrasound imaging. We have previously described the application of the translating apertures algorithm (TAA) to coherently acquire angular scatter data over a range of scattering angles. While this approach works well at the focus, it suffers from poor depth of field (DOF) due to a finite aperture size. Furthermore, application of the TAA with large focused apertures entails a tradeoff between spatial resolution and scattering angle resolution. While large multielement apertures improve spatial resolution, they encompass many permutations of transmit/receive element pairs. This results in the simultaneous interrogation of multiple scattering angles, limiting angular resolution. We propose a synthetic aperture imaging scheme that achieves both high spatial resolution and high angular resolution. In backscatter acquisition mode, we transmit successively from single transducer elements, while receiving on the same element. Other scattering angles are interrogated by successively transmitting and receiving on different single elements chosen with the appropriate spatial separation between them. Thus any given image is formed using only transmit/receive element pairs at a single separation. This synthetic aperture approach minimizes averaging across scattering angles, and yields excellent angular resolution. Likewise, synthetic aperture methods allow us to build large effective apertures to maintain a high spatial resolution. Synthetic dynamic focusing and dynamic apodization are applied to further improve spatial resolution and DOF. We present simulation results and experimental results obtained using a GE Logiq 700MR system modified to obtain synthetic aperture TAA data. Images of wire targets exhibit high DOF and spatial resolution. We also present a novel approach for combining angular scatter data to effectively reduce grating lobes. With this approach we have

  6. A user's manual for the NASA/JPL synthetic aperture radar and the NASA/JPL L and C band scatterometers

    NASA Astrophysics Data System (ADS)

    Thompson, T. W.

    1983-06-01

    Airborne synthetic aperture radars and scatterometers are operated with the goals of acquiring data to support shuttle imaging radars and support ongoing basic active microwave remote sensing research. The aircraft synthetic aperture radar is an L-band system at the 25-cm wavelength and normally operates on the CV-990 research aircraft. This radar system will be upgraded to operate at both the L-band and C-band. The aircraft scatterometers are two independent radar systems that operate at 6.3-cm and 18.8-cm wavelengths. They are normally flown on the C-130 research aircraft. These radars will be operated on 10 data flights each year to provide data to NASA-approved users. Data flights will be devoted to Shuttle Imaging Radar-B (SIR-B) underflights. Standard data products for the synthetic aperture radars include both optical and digital images. Standard data products for the scatterometers include computer compatible tapes with listings of radar cross sections (sigma-nought) versus angle of incidence. An overview of these radars and their operational procedures is provided by this user's manual.

  7. A user's manual for the NASA/JPL synthetic aperture radar and the NASA/JPL L and C band scatterometers

    NASA Technical Reports Server (NTRS)

    Thompson, T. W.

    1983-01-01

    Airborne synthetic aperture radars and scatterometers are operated with the goals of acquiring data to support shuttle imaging radars and support ongoing basic active microwave remote sensing research. The aircraft synthetic aperture radar is an L-band system at the 25-cm wavelength and normally operates on the CV-990 research aircraft. This radar system will be upgraded to operate at both the L-band and C-band. The aircraft scatterometers are two independent radar systems that operate at 6.3-cm and 18.8-cm wavelengths. They are normally flown on the C-130 research aircraft. These radars will be operated on 10 data flights each year to provide data to NASA-approved users. Data flights will be devoted to Shuttle Imaging Radar-B (SIR-B) underflights. Standard data products for the synthetic aperture radars include both optical and digital images. Standard data products for the scatterometers include computer compatible tapes with listings of radar cross sections (sigma-nought) versus angle of incidence. An overview of these radars and their operational procedures is provided by this user's manual.

  8. The NASA/JPL Airborne Synthetic Aperture Radar System

    NASA Technical Reports Server (NTRS)

    Kim, Yun-Jin; Lou, Yun-Ling; vanZyl, Jakob

    1996-01-01

    The NASA/JPL airborne SAR (AIRSAR) system operates in the fully polarimetric mode at P-, L- and C-band simultaneously or in the interferometric mode in both L- and C-band simultaneously. The system became operational in late 1987 and flew its first mission aboard a DC-8 aircraft operated by NASA's Ames Research Center in Mountain View, California. Since then, the AIRSAR has flown missions every year and acquired images in North, Central and South America, Europe and Australia. In this paper, we will briefly describe the instrument characteristics, the evolution of the various radar modes, the instrument performance, and improvement in the knowledge of the positioning and attitude information of the radar. In addition, we will summarize the progress of the data processing effort especially in the interferometry processing. Finally, we will address the issue of processing and calibrating the cross-track interferometry (XTI) data.

  9. Space Radar Image of Honolulu, Oahu, Hawaii

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This spaceborne radar image shows the city of Honolulu, Hawaii and adjacent areas on the island of Oahu. Honolulu lies on the south shore of the island, along the bottom of this image. Diamond Head, an extinct volcanic crater, is seen in the lower right. The bright white strip left of Diamond Head is the Waikiki Beach area. Further west are the downtown area and harbor. Runways of the airport can be seen in the lower left. The Koolau mountain range runs through the center of the image. The steep cliffs on the north side of the range are thought to be remnants of massive landslides that ripped apart the volcanic mountains that built the island thousands of years ago. On the north shore of the island are the Mokapu peninsula and Kaneohe Bay. Densely vegetated areas appear green in this radar image, while urban areas generally appear orange, red or white. Images such as this can be used by land use planners to monitor urban development and its effect on the tropical environment. The image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttleEndeavour on October 6, 1994.The image is 20.6 kilometers by 31.0kilometers (12.8 miles by 19.2 miles) and is centered at 21.4degrees North latitude, 157.8 degrees West longitude. North is toward the upper left. The colors are assigned to different radarfrequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted and received; green is L-band, horizontally transmitted, vertically received; and blue is C-band, horizontally transmitted, vertically received. SIR-C/X-SAR,a joint mission of the German, Italian, and United States space agencies, is part of NASA's Mission to Planet Earth.

  10. Space radar image of New Orleans, Louisiana

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This image of the area surrounding the city of New Orleans, Louisiana in the southeastern United States demonstrates the ability of multi-frequency imaging radar to distinguish different types of land cover. The dark area in the center is Lake Pontchartrain. The thin line running across the lake is a causeway connecting New Orleans to the city of Mandeville. Lake Borgne is the dark area in the lower right of the image. The Mississippi River appears as a dark, wavy line in the lower left. The white dots on the Mississippi are ships. The French Quarter is the brownish square near the left center of the image. Lakefront Airport, a field used mostly for general aviation, is the bright spot near the center, jutting out into Lake Pontchartrain. The image was acquired by the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) during orbit 39 of space shuttle Endeavour on October 2, 1994. The area is located at 30.10 degrees north latitude and 89.1 degrees west longitude. The area shown is approximately 100 kilometers (60 miles) by 50 kilometers (30 miles). The colors in this image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the C-band (horizontally transmitted and received); blue represents the L-band (vertically transmitted and received). The green areas are primarily vegetation consisting of swamp land and swamp forest (bayou) growing on sandy soil, while the pink areas are associated with reflections from buildings in urban and suburban areas. Different tones and colors in the vegetation areas will be studied by scientists to see how effective imaging radar data is in discriminating between different types of wetlands. Accurate maps of coastal wetland areas are important to ecologists studying wild fowl and the coastal environment.

  11. Concepts and Technologies for Synthetic Aperture Radar from MEO and Geosynchronous orbits

    NASA Technical Reports Server (NTRS)

    Edelstein, Wendy N.; Madsen, Soren; Moussessian, Alina; Chen, Curtis

    2004-01-01

    The area accessible from a spaceborne imaging radar, e.g. a synthetic aperture radar (SAR), generally increases with the elevation of the satellite while the map coverage rate is a more complicated function of platform velocity and beam agility. The coverage of a low Earth orbit (LEO) satellite is basically given by the fast ground velocity times the relatively narrow swath width. The instantaneously accessible area will be limited to some hundreds of kilometers away from the sub-satellite point. In the other extreme, the sub-satellite point of a SAR in geosynchronous orbit will move relatively slowly, while the area which can be accessed at any given time is very large, reaching thousands of kilometers from the subsatellite point. To effective1y use the accessibility provided by a high vantage point, very large antennas with electronically steered beams are required.

  12. Space Radar Image of Star City, Russia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This radar image shows the Star City cosmonaut training center, east of Moscow, Russia. Four American astronauts are training here for future long-duration flights aboard the Russian Mir space station. These joint flights are giving NASA and the Russian Space Agency experience necessary for the construction of the international Alpha space station, beginning in late 1997. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR), on its 62nd orbit on October 3, 1994. This Star City image is centered at 55.55 degrees north latitude and 38.0 degrees east longitude. The area shown is approximately 32 kilometers by 49 kilometers (20 miles by 30 miles). North is to the top in this image. The radar illumination is from the top of the image. The image was produced using three channels of SIR-C radar data: red indicates L-band (23 cm wavelength, horizontally transmitted and received); green indicates L-band (horizontally transmitted and vertically received); blue indicates C-band (6 cm wavelength, horizontally transmitted and vertically received). In general, dark pink areas are agricultural; pink and light blue areas are urban communities; black areas represent lakes and rivers; dark blue areas are cleared forest; and light green areas are forested. The prominent black runways just right of center are Shchelkovo Airfield, about 4 km long. The textured pale blue-green area east and southeast of Shchelkovo Airfield is forest. Just east of the runways is a thin railroad line running southeast; the Star City compound lies just east of the small bend in the rail line. Star City contains the living quarters and training facilities for Russian cosmonauts and their families. Moscow's inner loop road is visible at the lower left edge of the image. The Kremlin is just off the left edge, on the banks of the meandering Moskva River. The Klyazma River snakes to the southeast from the reservoir in the upper left (shown in bright red

  13. SRTM Radar - Landsat Image Comparison, Patagonia, Argentina

    NASA Technical Reports Server (NTRS)

    2000-01-01

    various differences among all of these images illustrate the importance of illumination wavelength in image interpretation.

    The Landsat 7 Thematic Mapper images used here were provided to the SRTM project by the United States Geological Survey, Earth Resources Observation Systems (EROS) Data Center, Sioux Falls, South Dakota.

    The radar images shown here were acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11,2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise,Washington, DC.

    Size (top set): 21.3 kilometers (13.2 miles) x 25.0 kilometers (15.5 miles) Size (bottom set): 44.1 kilometers (27.3 miles) x 56.0 kilometers (34.7 miles) Location: 41.5 deg. South lat., 69 deg. West lon. Orientation: North toward upper left (top set), North toward upper right (bottom set) Image Data: Landsat bands 1,2,3 (left); SRTM Radar (middle); Landsat band 7 (right) Date Acquired: February 19, 2000 (SRTM), January 22, 2000 (Landsat)

  14. Progress report on the NASA/JPL airborne synthetic aperture radar system

    NASA Technical Reports Server (NTRS)

    Lou, Y.; Imel, D.; Chu, A.; Miller, T.; Moller, D.; Skotnicki, W.

    2001-01-01

    AIRSAR has served as a test-bed for both imaging radar techniques and radar technologies for over a decade. In fact, the polarimetric, cross-track interferometric, and along-track introferometric radar techniques were all developed using AIRSAR.

  15. Space Radar Image of Tuva, Central Asia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This spaceborne radar image shows part of the remote central Asian region of Tuva, an autonomous republic of the Russian Federation. Tuva is a mostly mountainous region that lies between western Mongolia and southern Siberia. This image shows the area just south of the republic's capital of Kyzyl. Most of the red, pink and blue areas in the image are agricultural fields of a large collective farming complex that was developed during the era of the Soviet Union. Traditional agricultural activity in the region, still active in remote areas, revolves around practices of nomadic livestock herding. White areas on the image are north-facing hillsides, which develop denser forests than south-facing slopes. The river in the upper right is one of the two major branches of the Yenesey River. Tuva has received some notoriety in recent years due to the intense interest of the celebrated Caltech physicist Dr. Richard Feynman, chronicled in the book 'Tuva or Bust' by Ralph Leighton. The image was acquired by Spaceborne Imaging Radar-C/X-Band SyntheticAperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour onOctober 1, 1994. The image is 56 kilometers by 74 kilometers (35 miles by 46 miles) and is centered at 51.5 degrees north latitude, 95.1 degrees east longitude. North is toward the upper right. The colors are assigned to different radar fequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted andreceived; green is L-band, horizontally transmitted and vertically received; and blue is C-band, horizontally transmitted and verticallyreceived. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to PlanetEarth program.

  16. Space Radar Image of Pishan, China

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This radar image is centered near the small town of Pishan in northwest China, about 280 km (174 miles) southeast of the city of Kashgar along the ancient Silk Route in the Taklamakan desert of the Xinjiang Province. Geologists are using this radar image as a map to study past climate changes and tectonics of the area. The irregular lavender branching patterns in the center of the image are the remains of ancient alluvial fans, gravel deposits that have accumulated at the base of the mountains during times of wetter climate. The subtle striped pattern cutting across the ancient fans are caused by thrusting of the Kun Lun Mountains north. This motion is caused by the continuing plate-tectonic collision of India with Asia. Modern fans show up as large lavender triangles above the ancient fan deposits. Yellow areas on the modern fans are vegetated oases. The gridded pattern results from the alignment of poplar trees that have been planted as wind breaks. The reservoir at the top of the image is part of a sophisticated irrigation system that supplies water to the oases. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour in April 1994. This image is centered at 37.4 degrees north latitude, 78.3 degrees east longitude and shows an area approximately 50 km by 100 km (31 miles by 62 miles). The colors are assigned to different frequencies and polarizations of the radar as follows: Red is L-band horizontally transmitted, horizontally received; green is L-band horizontally transmitted, vertically received; and blue is C-band horizontally transmitted and vertically received. SIR-C/X-SAR, a joint mission of the German, Italian, and the United States space agencies, is part of NASA's Mission to Planet Earth.

  17. The Use of Multiple-Polarization Data in Foliage Penetrating (FOPEN) Synthetic Aperture Radar (SAR) Applications

    SciTech Connect

    RICHARDS,JOHN A.

    2002-07-01

    Foliage penetrating (FOPEN) synthetic aperture radar (SAR) systems are capable of producing images of targets concealed under a foliage canopy. The quality and interpretability of these images, however, is generally limited by dense foliage clutter and by fundamental foliage-induced image degradation. Use of a polarimetric SAR to provide multiple polarization channels can mitigate these effects by offering target and scene information beyond that provided by a single-polarization SAR. This paper presents the results of a literature survey to investigate the use of multiple-polarization data in conjunction with FOPEN SAR applications. The effects of foliage propagation on SAR image quality are briefly summarized. Various approaches to multiple-polarization-based FOPEN target detection are described. Although literature concerning FOPEN target recognition is scarce, the use of multiple-polarization data for in-the-clear target recognition is described. The applicability of various target detection and recognition applications for use with concealed target SAR (CTSAR) imagery is considered.

  18. Method and apparatus for Delta Kappa synthetic aperture radar measurement of ocean current

    NASA Technical Reports Server (NTRS)

    Jain, A. (Inventor)

    1985-01-01

    A synthetic aperture radar (SAR) employed for delta k measurement of ocean current from a spacecraft without the need for a narrow beam and long observation times. The SAR signal is compressed to provide image data for different sections of the chirp band width, equivalent to frequencies and a common area for the separate image fields is selected. The image for the selected area at each frequency is deconvolved to obtain the image signals for the different frequencies and the same area. A product of pairs of signals is formed, Fourier transformed and squared. The spectrum thus obtained from different areas for the same pair of frequencies are added to provide an improved signal to noise ratio. The shift of the peak from the center of the spectrum is measured and compared to the expected shift due to the phase velocity of the Bragg scattering wave. Any difference is a measure of current velocity v sub o (delta k).

  19. Space Radar Image of Raco Biomass Map

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This biomass map of the Raco, Michigan, area was produced from data acquired by the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard space shuttle Endeavour. Biomass is the amount of plant material on an area of Earth's surface. Radar can directly sense the quantity and organizational structure of the woody biomass in the forest. Science team members at the University of Michigan used the radar data to estimate the standing biomass for this Raco site in the Upper Peninsula of Michigan. Detailed surveys of 70 forest stands will be used to assess the accuracy of these techniques. The seasonal growth of terrestrial plants, and forests in particular, leads to the temporary storage of large amounts of carbon, which could directly affect changes in global climate. In order to accurately predict future global change, scientists need detailed information about current distribution of vegetation types and the amount of biomass present around the globe. Optical techniques to determine net biomass are frustrated by chronic cloud-cover. Imaging radar can penetrate through cloud-cover with negligible signal losses. Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German

  20. Space Radar Image of Patagonian Ice Fields

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This pair of images illustrates the ability of multi-parameter radar imaging sensors such as the Spaceborne Imaging Radar-C/X-band Synthetic Aperture radar to detect climate-related changes on the Patagonian ice fields in the Andes Mountains of Chile and Argentina. The images show nearly the same area of the south Patagonian ice field as it was imaged during two space shuttle flights in 1994 that were conducted five-and-a-half months apart. The images, centered at 49.0 degrees south latitude and 73.5degrees west longitude, include several large outlet glaciers. The images were acquired by SIR-C/X-SAR on board the space shuttle Endeavour during April and October 1994. The top image was acquired on April 14, 1994, at 10:46 p.m. local time, while the bottom image was acquired on October 5,1994, at 10:57 p.m. local time. Both were acquired during the 77th orbit of the space shuttle. The area shown is approximately 100 kilometers by 58 kilometers (62 miles by 36 miles) with north toward the upper right. The colors in the images were obtained using the following radar channels: red represents the C-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted and received); blue represents the L-band (horizontally transmitted and vertically received). The overall dark tone of the colors in the central portion of the April image indicates that the interior of the ice field is covered with thick wet snow. The outlet glaciers, consisting of rough bare ice, are the brightly colored yellow and purple lobes which terminate at calving fronts into the dark waters of lakes and fiords. During the second mission the temperatures were colder and the corresponding change in snow and ice conditions is readily apparent by comparing the images. The interior of the ice field is brighter because of increased radar return from the dryer snow. The distinct green/orange boundary on the ice field indicates an abrupt change in the structure of the snowcap

  1. Space Radar Image of Florence, Italy

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This radar image shows land use patterns in and around the city of Florence, Italy, shown here in the center of the image. Florence is situated on a plain in the Chianti Hill region of Central Italy. The Arno River flows through town and is visible as the dark line running from the upper right to the bottom center of the image. The city is home to some of the world's most famous art museums. The bridges seen crossing the Arno, shown as faint red lines in the upper right portion of the image, were all sacked during World War II with the exception of the Ponte Vecchio, which remains as Florence's only covered bridge. The large, black V-shaped feature near the center of the image is the Florence Railroad Station. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the Space Shuttle Endeavour on April 14, 1994. SIR-C/X-SAR, a joint mission of the German, Italian, and United States space agencies, is part of NASA's Mission to Planet Earth. This image is centered at 43.7 degrees north latitude and 11.15 degrees east longitude with North toward the upper left of the image. The area shown measures 20 kilometers by 17 kilometers (12.4 miles by 10.6 miles). The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band horizontally transmitted, horizontally received; green is L-band horizontally transmitted, vertically received; blue is C-band horizontally transmitted, vertically received.

  2. UHF Microstrip Antenna Array for Synthetic- Aperture Radar

    NASA Technical Reports Server (NTRS)

    Thomas, Robert F.; Huang, John

    2003-01-01

    An ultra-high-frequency microstrippatch antenna has been built for use in airborne synthetic-aperture radar (SAR). The antenna design satisfies requirements specific to the GeoSAR program, which is dedicated to the development of a terrain-mapping SAR system that can provide information on geology, seismicity, vegetation, and other terrain-related topics. One of the requirements is for ultra-wide-band performance: the antenna must be capable of operating with dual linear polarization in the frequency range of 350 plus or minus 80 MHz, with a peak gain of 10 dB at the middle frequency of 350 MHz and a gain of at least 8 dB at the upper and lower ends (270 and 430 MHz) of the band. Another requirement is compactness: the antenna must fit in the wingtip pod of a Gulfstream II airplane. The antenna includes a linear array of microstrip-patch radiating elements supported over square cavities. Each patch is square (except for small corner cuts) and has a small square hole at its center.

  3. Space Radar Image of County Kerry, Ireland

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The Iveragh Peninsula, one of the four peninsulas in southwestern Ireland, is shown in this spaceborne radar image. The lakes of Killarney National Park are the green patches on the left side of the image. The mountains to the right of the lakes include the highest peaks (1,036 meters or 3,400 feet) in Ireland. The patchwork patterns between the mountains are areas of farming and grazing. The delicate patterns in the water are caused by refraction of ocean waves around the peninsula edges and islands, including Skellig Rocks at the right edge of the image. The Skelligs are home to a 15th century monastery and flocks of puffins. The region is part of County Kerry and includes a road called the 'Ring of Kerry' that is one of the most famous tourist routes in Ireland. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the Space Shuttle Endeavour on April 12, 1994. The image is 82 kilometers by 42 kilometers (51 miles by 26 miles) and is centered at 52.0 degrees north latitude, 9.9 degrees west longitude. North is toward the lower left. The colors are assigned to different radar frequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted and received; green is L-band, vertically transmitted and received; and blue is C-band, vertically transmitted and received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

  4. Space Radar Image of Reunion Island

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This radar image shows the volcanic island of Reunion, about 700 km (434 miles) east of Madagascar in the southwest Indian Ocean. The southern half of the island is dominated by the active volcano, Piton de la Fournaise. This is one of the world's most active volcanoes, with more than 100 eruptions in the last 300 years. The most recent activity occurred in the vicinity of Dolomieu Crater, shown in the lower center of the image within a horseshoe-shaped collapse zone. Recent lava flows appear in shades of red, purple and orange. Light green areas are heavily vegetated forest, while much of the purple area near the coast is farmland. The radar illumination is from the left side of the image and dramatically emphasizes the precipitous cliffs at the edges of the central canyons of the island. These canyons are remnants from the collapse of formerly active parts of the volcanoes that built the island. This image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on October 5, 1994. The image is centered at 21.2 degrees south latitude, 55.6 degrees east longitude. The area shown is approximately 50 km by 80 km (31 miles by 50 miles). North is toward the upper right. Colors are assigned to different frequencies and polarizations of the radar as follows: red is L-band horizontally transmitted, vertically received; green is L-band horizontally transmitted, vertically received; and blue is C-band horizontally transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth.

  5. Space Radar Image of North Ecuador

    NASA Technical Reports Server (NTRS)

    1994-01-01

    A family of dormant volcanoes dominates the landscape in this radar image of the Andes Mountains in northern Ecuador. The city of Otavalo, shown in pink, and Lake Otavalo lie within the triangle formed by three volcanoes in the upper part of the image. These volcanoes are, clockwise from upper left, Mojanda, Imabura and Cusin. A lake partially fills the summit crater of Mojanda and a group of lava domes can be seen on the north flank. Geologists believe the most recent eruption of Mojanda was about 3,400 years ago. Much more recent activity has occurred at Cayambe, the large volcano at the bottom of the image. Massive mudflow deposits can be seen filling the valleys on the east (right) side of Cayambe. Cayambe last erupted about 600 years ago. Geologists are using radar to study volcanoes in the Andes to determine the history of eruptions and to identify potential threats the volcanoes pose to local communities. This image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on April 14, 1994. The image is centered at 0.1 degrees north latitude, 78.1 degrees west longitude. The area shown is approximately 50 km by 50 km (31 miles by 31 miles). North is toward the upper right. Colors are assigned to different frequencies and polarizations of the radar as follows: red is L-band horizontally transmitted, vertically received; green is L-band horizontally transmitted, vertically received; and blue is C-band horizontally transmitted, horizontally received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth.

  6. Space Radar Image of Hong Kong

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This spaceborne radar image shows part of the British territory of Hong Kong, adjacent to mainland China. The South China Sea is shown in dark blue and red on the image. Land surfaces are seen in shades of lighter blue and gold, including Hong Kong Island in the lower center, the Kowloon Peninsula in the upper right and many other small islands. The brightest yellow areas are the densely developed areas of Hong Kong's business and residential districts. The small yellow dots in the water are the many ships that make Hong Kong one of the busiest seaports in the Far East. Images such as this can be used by land-use planners to monitor urban development and its effect on the tropical environment. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on October 10, 1994. The image is 23 kilometers by 31 kilometers (14 miles by 19 miles) and is centered at 22.3 degreesnorth latitude, 114.1 degrees east longitude. North is toward theupper right. The colors are assigned to different radar frequenciesand polarizations of the radar as follows: red is L-band, verticallytransmitted and received; green is C-band, vertically transmitted and received; and blue is C-band minus L-band, both vertically transmitted and received. SIR-C/X-SAR, a joint mission of theGerman, Italian and United States space agencies, is part of NASA's Mission to Planet Earth.

  7. Understanding Volcanic Inflation of Long Valley Caldera, California, from Differential Synthetic Aperture Radar observations

    NASA Technical Reports Server (NTRS)

    Webb, F.; Hensley, S.; Rosen, P.; Langbein, J.

    1994-01-01

    The results using interferometric synthetic aperture radar(SAR) to measure the co-seismic displacement from the June 28, 1992 Landers earthquake suggest that this technique may be applicable to other problems in crustal deformation.

  8. Dual frequency Synthetic Aperture Radar (SAR) mission for monitoring our dynamic planet

    NASA Technical Reports Server (NTRS)

    Hilland, J.; Bard, S.; Key, R.; Kim, Y.; Vaze, P.; Huneycutt, B.

    2000-01-01

    Advances in spaceborne Synthetic Aperture Radar (SAR) remote sensing technology make it possible to acquire global-scale data sets that provide unique information about the Earth's continually changing surface characteristics.

  9. Detection of landmines and UXO using advanced synthetic aperture radar technology

    NASA Astrophysics Data System (ADS)

    Schreiber, Eric; Peichl, Markus; Dill, Stephan; Heinzel, Andreas; Bischeltsrieder, Florian

    2016-05-01

    A main problem of effective landmine and UXO decontamination is efficient and reliable detection and localization of suspicious objects in reasonable time. This requirement demands for fast sensors investigating large areas with sufficient spatial resolution and sensitivity. Ground penetrating radar (GPR) is a suitable tool and is considered as a complementing sensor since nearly two decades. However, most GPRs operate in very close distance to ground in a rather punctual method of operation. In contrast, synthetic aperture radar (SAR) is a technique allowing fast and laminar stand-off investigation of an area. TIRAMI-SAR is imaging radar at lower microwaves for fast close-in detection of buried and unburied objects on a larger area. This allows efficient confirmation of a threat by investigating such regions of detection by other sensors. For proper object detection sufficient spatial resolution is required. Hence the SAR principle is applied. SAR for landmine/UXO detection can be applied by side-looking radar moved on safe ground along the area of interest, being typically the un-safe ground. Additionally, reliable detection of buried and unburied objects requires sufficient suppression of background clutter. For that purpose TIRAMI-SAR is using several antennas in multi-static configuration and wave polarization together with advanced SAR processing. The advantages and necessity of a multi-static antenna configuration for this kind of GPR approach is illustrated in the paper.

  10. Space Radar Image of Rocky Mountains, Montana

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a three-dimensional perspective of the eastern front range of the Rocky Mountains, about 120 kilometers (75 miles) west of Great Falls, Montana. The image was created by combining two spaceborne radar images using a technique known as interferometry. Visualizations like this are useful to scientists because they show the shapes of the topographic features such as mountains and valleys. This technique helps to clarify the relationships of the different types of materials on the surface detected by the radar. The view is looking south-southeast. Along the right edge of the image is the valley of the north fork of the Sun River. The western edge of the Great Plains appears on the left side. The valleys in the lower center, running off into the plains on the left, are branches of the Teton River. The highest mountains are at elevations of 2,860 meters (9,390 feet), and the plains are about 1,400 meters (4,500 feet) above sea level. The dark brown areas are grasslands, bright green areas are farms, light brown, orange and purple areas are scrub and forest, and bright white and blue areas are steep rocky slopes. The two radar images were taken on successive days by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) on board the space shuttle Endeavour in October 1994. The digital elevation map was produced using radar interferometry, a process in which radar data are acquired on different passes of the space shuttle. The two data passes are compared to obtain elevation information. Radar image data are draped over the topography to provide the color with the following assignments: red is L-band vertically transmitted, vertically received; green is C-band vertically transmitted, vertically received; and blue are the differences seen in the L-band data between the two days. This image is centered near 47.7 degrees north latitude and 112.7 degrees west longitude. No vertical exaggeration factor has been applied to the data. SIR-C/X-SAR, a

  11. Space Radar Image of San Francisco, California

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This image of San Francisco, California shows how the radar distinguishes between densely populated urban areas and nearby areas that are relatively unsettled. Downtown San Francisco is at the center and the city of Oakland is at the right across the San Francisco Bay. Some city areas, such as the South of Market, called the SOMA district in San Francisco, appear bright red due to the alignment of streets and buildings to the incoming radar beam. Various bridges in the area are also visible including the Golden Gate Bridge (left center) at the opening of San Francisco Bay, the Bay Bridge (right center) connecting San Francisco and Oakland, and the San Mateo Bridge (bottom center). All the dark areas on the image are relatively smooth water: the Pacific Ocean to the left, San Francisco Bay in the center, and various reservoirs. Two major faults bounding the San Francisco-Oakland urban areas are visible on this image. The San Andreas fault, on the San Francisco peninsula, is seen in the lower left of the image. The fault trace is the straight feature filled with linear reservoirs which appear dark. The Hayward fault is the straight feature on the right side of the image between the urban areas and the hillier terrain to the east. The image is about 42 kilometers by 58 kilometers (26 miles by 36 miles) with north toward the upper right. This area is centered at 37.83 degrees north latitude, 122.38 degrees east longitude. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture (SIR-C/X-SAR) imaging radar when it flew aboard the space shuttle Endeavour on October 3, 1994. SIR-C/X-SAR, a joint mission of the German, Italian and the United States space agencies, is part of NASA's Mission to Planet Earth.

  12. SPace Radar Image of Fort Irwin, California

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This image of Fort Irwin in California's Mojave Desert compares interferometric radar signatures topography -- data that were obtained by multiple imaging of the same region to produce three-dimensional elevation maps -- as it was obtained on October 7-8, 1994 by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar aboard the space shuttle Endeavour. Data were acquired using the L-band (24 centimeter wavelength) and C-band (6 centimeter wavelength). The image covers an area about 25 kilometers by 70 kilometers (15.5 miles by 43 miles). North is to the lower right of the image. The color contours shown are proportional to the topographic elevation. With a wavelength one-fourth that of the L-band, the results from the C-band cycle through the color contours four times faster for a given elevation change. Detailed comparisons of these multiple frequency data over different terrain types will provide insights in the future into wavelength-dependent effects of penetration and scattering on the topography measurement accuracy. Fort Irwin is an ideal site for such detailed digital elevation model comparisons because a number of high precision digital models of the area already exist from conventional measurements as well as from airborne interferometric SAR data. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human

  13. Space Radar Image of Raco Vegetation Map

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a vegetation map of the Raco, Michigan area produced from data acquired by the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard space shuttle Endeavour. The radar image, taken on April 9, 1994, has been used by science team members at the University of Michigan to produce detailed map of land cover. This image is centered at 46.4 degrees north latitude and 84.9 degrees west longitude. The imaged area is approximately 24 by 32 kilometers (15 by 20 miles). The Raco airport, which is a decommissioned military base, is easily identified by its triangular runway structure. An edge of Lake Superior, approximately 44 kilometers (27 miles) west of Sault Sainte Marie, appears in the top right of the image. In this land cover map each 30- by 30-meter (98- by 98-foot) spot is identified as either a water surface, bare ground, short vegetation, deciduous forest, lowland conifers or upland conifers. Different types of ground cover have different effects on Earth's chemical, water and energy cycles. By cataloguing ground cover in an area, scientists expect to better understand the processes of these cycles in a specific area. Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio

  14. Simulation of synthetic aperture imaging ladar (SAIL) for three-dimensional target model

    NASA Astrophysics Data System (ADS)

    Yi, Ning; Wu, Zhen-Sen

    2010-11-01

    In conventional imaging laser radar, the resolution of target is constrained by the diffraction-limited, which includes the beamwidth of the laser in the target plane and the telescope's aperture. Synthetic aperture imaging Ladar (SAIL) is an imaging technique which employs aperture synthesis with coherent laser radar, the resolution is determined by the total frequency spread of the source and is independent of range, so can achieve fine resolution in long range. Ray tracing is utilized here to obtain two-dimensional scattering properties from three-dimensional geometric model of actual target, and range-doppler algorithm is used for synthetic aperture process in laser image simulation. The results show that the SAIL can support better resolution.

  15. Interferometric Synthetic Aperture Microscopy: Computed Imaging for Scanned Coherent Microscopy.

    PubMed

    Davis, Brynmor J; Marks, Daniel L; Ralston, Tyler S; Carney, P Scott; Boppart, Stephen A

    2008-06-01

    Three-dimensional image formation in microscopy is greatly enhanced by the use of computed imaging techniques. In particular, Interferometric Synthetic Aperture Microscopy (ISAM) allows the removal of out-of-focus blur in broadband, coherent microscopy. Earlier methods, such as optical coherence tomography (OCT), utilize interferometric ranging, but do not apply computed imaging methods and therefore must scan the focal depth to acquire extended volumetric images. ISAM removes the need to scan the focus by allowing volumetric image reconstruction from data collected at a single focal depth. ISAM signal processing techniques are similar to the Fourier migration methods of seismology and the Fourier reconstruction methods of Synthetic Aperture Radar (SAR). In this article ISAM is described and the close ties between ISAM and SAR are explored. ISAM and a simple strip-map SAR system are placed in a common mathematical framework and compared to OCT and radar respectively. This article is intended to serve as a review of ISAM, and will be especially useful to readers with a background in SAR. PMID:20948975

  16. Interferometric Synthetic Aperture Microscopy: Computed Imaging for Scanned Coherent Microscopy

    PubMed Central

    Davis, Brynmor. J.; Marks, Daniel. L.; Ralston, Tyler. S.; Carney, P. Scott; Boppart, Stephen. A.

    2008-01-01

    Three-dimensional image formation in microscopy is greatly enhanced by the use of computed imaging techniques. In particular, Interferometric Synthetic Aperture Microscopy (ISAM) allows the removal of out-of-focus blur in broadband, coherent microscopy. Earlier methods, such as optical coherence tomography (OCT), utilize interferometric ranging, but do not apply computed imaging methods and therefore must scan the focal depth to acquire extended volumetric images. ISAM removes the need to scan the focus by allowing volumetric image reconstruction from data collected at a single focal depth. ISAM signal processing techniques are similar to the Fourier migration methods of seismology and the Fourier reconstruction methods of Synthetic Aperture Radar (SAR). In this article ISAM is described and the close ties between ISAM and SAR are explored. ISAM and a simple strip-map SAR system are placed in a common mathematical framework and compared to OCT and radar respectively. This article is intended to serve as a review of ISAM, and will be especially useful to readers with a background in SAR. PMID:20948975

  17. Space Radar Image of Kilauea Volcano, Hawaii

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This three-dimensional image of the volcano Kilauea was generated based on interferometric fringes derived from two X-band Synthetic Aperture Radar data takes on April 13, 1994 and October 4, 1994. The altitude lines are based on quantitative interpolation of the topographic fringes. The level difference between neighboring altitude lines is 20 meters (66 feet). The ground area covers 12 kilometers by 4 kilometers (7.5 miles by 2.5 miles). The altitude difference in the image is about 500 meters (1,640 feet). The volcano is located around 19.58 degrees north latitude and 155.55 degrees west longitude. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI), with the Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.V.(DLR), the major partner in science, operations and data processing of X-SAR. The Instituto Ricerca Elettromagnetismo Componenti Elettronici (IRECE) at the University of Naples was a partner in the interferometry analysis.

  18. Experimental 0.22 THz Stepped Frequency Radar System for ISAR Imaging

    NASA Astrophysics Data System (ADS)

    Liang, Mei Yan; Zhang, Cun Lin; Zhao, Ran; Zhao, Yue Jin

    2014-09-01

    High resolution inverse synthetic aperture radar (ISAR) imaging is demonstrated by using a 0.22 THz stepped-frequency (SF) imaging radar system. The synthesis bandwidth of the terahertz (THz) SF radar is 12 GHz, which are beneficial for high resolution imaging. The resolution of ISAR image can reach centimeter-scale with the use of Range-Doppler algorithm (RDA). Results indicate that high resolution ISAR imaging is realized by using 0.22THz SF radar coupled with turntable scanning, which can provide foundations for further research on high-resolution radar image in the THz band.

  19. Space Radar Image of Oil Slicks

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a radar image of an offshore drilling field about 150 km (93 miles) west of Bombay, India, in the Arabian Sea. The dark streaks are extensive oil slicks surrounding many of the drilling platforms, which appear as bright white spots. Radar images are useful for detecting and measuring the extent of oil seepages on the ocean surface, from both natural and industrial sources. The long, thin streaks extending from many of the platforms are spreading across the sea surface, pushed by local winds. The larger dark patches are dispersed slicks that were likely discharged earlier than the longer streaks, when the winds were probably from a different direction. The dispersed oil will eventually spread out over the more dense water and become a layer which is a single molecule thick. Many forms of oil, both from biological and from petroleum sources, smooth out the ocean surface, causing the area to appear dark in radar images. There are also two forms of ocean waves shown in this image. The dominant group of large waves (upper center) are called internal waves. These waves are formed below the ocean surface at the boundary between layers of warm and cold water and they appear in the radar image because of the way they change the ocean surface. Ocean swells, which are waves generated by winds, are shown throughout the image but are most distinct in the blue area adjacent to the internal waves. Identification of waves provide oceanographers with information about the smaller scale dynamic processes of the ocean. This image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on October 9, 1994. The colors are assigned to different frequencies and polarizations of the radar as follows: Red is L-band vertically transmitted, vertically received; green is the average of L-band vertically transmitted, vertically received and C-band vertically transmitted, vertically received; blue is C

  20. Space Radar Image of Sacramento, California

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a spaceborne radar image of the city of Sacramento, the capital of California. Urban areas appear pink and the surrounding agricultural areas are green and blue. The Sacramento River is the curving dark line running from the left side of the image (northwest) to the bottom right. The American River is the dark curving line in the center. Sacramento is built at the junction of these two rivers and the state Capitol building is in the bright pink-white area southeast of the junction. The straighter dark line (lower center) is the Sacramento River Deep Water Ship Channel which allows ship access from San Francisco. The black areas in the center are the runways of the Sacramento Executive airport. The city of Davis, California is seen as a pink area in lower left. This image was acquired by Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on October 2, 1994. The image is 27.0 kilometers by 38.4 kilometers (17 miles by 24 miles) and is centered at 38.6 degrees North latitude, 125.1 degrees West longitude. North is toward the upper left. The colors are assigned to different radar frequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted and received; green is C-band, horizontally transmitted and received; and blue is C-band, horizontally transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian, and United States space agencies, is part of NASA's Mission to Planet Earth.

  1. The Information Content of Interferometric Synthetic Aperture Radar: Vegetation and Underlying Surface Topography

    NASA Technical Reports Server (NTRS)

    Treuhaft, Robert N.

    1996-01-01

    This paper first gives a heuristic description of the sensitivity of Interferometric Synthetic Aperture Radar to vertical vegetation distributions and underlying surface topography. A parameter estimation scenario is then described in which the Interferometric Synthetic Aperture Radar cross-correlation amplitude and phase are the observations from which vegetation and surface topographic parameters are estimated. It is shown that, even in the homogeneous-layer model of the vegetation, the number of parameters needed to describe the vegetation and underlying topography exceeds the number of Interferometric Synthetic Aperture Radar observations for single-baseline, single-frequency, single-incidence-angle, single-polarization Interferometric Synthetic Aperture Radar. Using ancillary ground-truth data to compensate for the underdetermination of the parameters, forest depths are estimated from the INSAR data. A recently-analyzed multibaseline data set is also discussed and the potential for stand-alone Interferometric Synthetic Aperture Radar parameter estimation is assessed. The potential of combining the information content of Interferometric Synthetic Aperture Radar with that of infrared/optical remote sensing data is briefly discussed.

  2. Space Radar Image of Harvard Forest

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a radar image of the area surrounding the Harvard Forest in north-central Massachusetts that has been operated as a ecological research facility by Harvard University since 1907. At the center of the image is the Quabbin Reservoir, and the Connecticut River is at the lower left of the image. The Harvard Forest itself is just above the reservoir. Researchers are comparing the naturally occurring physical disturbances in the forest and the recent and projected chemical disturbances and their effects on the forest ecosystem. Agricultural land appears dark blue/purple, along with low shrub vegetation and some wetlands. Urban development is bright pink; the yellow to green tints are conifer-dominated vegetation with the pitch pine sand plain at the middle left edge of the image appearing very distinctive. The green tint may indicate pure pine plantation stands, and deciduous broadleaf trees appear gray/pink with perhaps wetter sites being pinker. This image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour. SIR-C/X-SAR, a joint mission of the German, Italian and the United States space agencies, is part of NASA's Mission to Planet Earth. The image is centered at 42.50 degrees North latitude and 72.33 degrees West longitude and covers an area of 53 kilometers 63 by kilometers (33 miles by 39 miles). The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band horizontally transmitted and horizontally received; green is L-band horizontally transmitted and vertically received; and blue is C-band horizontally transmitted and horizontally received.

  3. Charge-coupled device data processor for an airborne imaging radar system

    NASA Technical Reports Server (NTRS)

    Arens, W. E. (Inventor)

    1977-01-01

    Processing of raw analog echo data from synthetic aperture radar receiver into images on board an airborne radar platform is discussed. Processing is made feasible by utilizing charge-coupled devices (CCD). CCD circuits are utilized to perform input sampling, presumming, range correlation and azimuth correlation in the analog domain. These radar data processing functions are implemented for single-look or multiple-look imaging radar systems.

  4. Evaluation Digital Elevation Model Generated by Synthetic Aperture Radar Data

    NASA Astrophysics Data System (ADS)

    Makineci, H. B.; Karabörk, H.

    2016-06-01

    Digital elevation model, showing the physical and topographical situation of the earth, is defined a tree-dimensional digital model obtained from the elevation of the surface by using of selected an appropriate interpolation method. DEMs are used in many areas such as management of natural resources, engineering and infrastructure projects, disaster and risk analysis, archaeology, security, aviation, forestry, energy, topographic mapping, landslide and flood analysis, Geographic Information Systems (GIS). Digital elevation models, which are the fundamental components of cartography, is calculated by many methods. Digital elevation models can be obtained terrestrial methods or data obtained by digitization of maps by processing the digital platform in general. Today, Digital elevation model data is generated by the processing of stereo optical satellite images, radar images (radargrammetry, interferometry) and lidar data using remote sensing and photogrammetric techniques with the help of improving technology. One of the fundamental components of remote sensing radar technology is very advanced nowadays. In response to this progress it began to be used more frequently in various fields. Determining the shape of topography and creating digital elevation model comes the beginning topics of these areas. It is aimed in this work , the differences of evaluation of quality between Sentinel-1A SAR image ,which is sent by European Space Agency ESA and Interferometry Wide Swath imaging mode and C band type , and DTED-2 (Digital Terrain Elevation Data) and application between them. The application includes RMS static method for detecting precision of data. Results show us to variance of points make a high decrease from mountain area to plane area.

  5. Contribution of multitemporal polarimetric synthetic aperture radar data for monitoring winter wheat and rapeseed crops

    NASA Astrophysics Data System (ADS)

    Betbeder, Julie; Fieuzal, Remy; Philippets, Yannick; Ferro-Famil, Laurent; Baup, Frederic

    2016-04-01

    This paper aims to evaluate the contribution of multitemporal polarimetric synthetic aperture radar (SAR) data for winter wheat and rapeseed crops parameters [height, leaf area index, and dry biomass (DB)] estimation, during their whole vegetation cycles in comparison to backscattering coefficients and optical data. Angular sensitivities and dynamics of polarimetric indicators were also analyzed following the growth stages of these two common crop types using, in total, 14 radar images (Radarsat-2), 16 optical images (Formosat-2, Spot-4/5), and numerous ground data. The results of this study show the importance of correcting the angular effect on SAR signals especially for copolarized signals and polarimetric indicators associated to single-bounce scattering mechanisms. The analysis of the temporal dynamic of polarimetric indicators has shown their high potential to detect crop growth changes. Moreover, this study shows the high interest of using SAR parameters (backscattering coefficients and polarimetric indicators) for crop parameters estimation during the whole vegetation cycle instead of optical vegetation index. They particularly revealed their high potential for rapeseed height and DB monitoring [i.e., Shannon entropy polarimetry (r2=0.70) and radar vegetation index (r2=0.80), respectively].

  6. Application of equalization notch to improve synthetic aperture radar coherent data products

    NASA Astrophysics Data System (ADS)

    Musgrove, Cameron; West, James C.

    2015-05-01

    Interference and interference mitigation techniques degrade synthetic aperture radar (SAR) coherent data products. Radars utilizing stretch processing present a unique challenge for many mitigation techniques because the interference signal itself is modified through stretch processing from its original signal characteristics. Many sources of interference, including constant tones, are only present within the fast-time sample data for a limited number of samples, depending on the radar and interference bandwidth. Adaptive filtering algorithms to estimate and remove the interference signal that rely upon assuming stationary interference signal characteristics can be ineffective. An effective mitigation method, called notching, forces the value of the data samples containing interference to zero. However, as the number of data samples set to zero increases, image distortion and loss of resolution degrade both the image product and any second order image products. Techniques to repair image distortions,1 are effective for point-like targets. However, these techniques are not designed to model and repair distortions in SAR image terrain. Good terrain coherence is important for SAR second order image products because terrain occupies the majority of many scenes. For the case of coherent change detection it is the terrain coherence itself that determines the quality of the change detection image. This paper proposes an unique equalization technique that improves coherence over existing notching techniques. First, the proposed algorithm limits mitigation to only the samples containing interference, unlike adaptive filtering algorithms, so the remaining samples are not modified. Additionally, the mitigation adapts to changing interference power such that the resulting correction equalizes the power across the data samples. The result is reduced distortion and improved coherence for the terrain. SAR data demonstrates improved coherence from the proposed equalization

  7. Space Radar Image of Maui, Hawaii

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This spaceborne radar image shows the 'Valley Island' of Maui, Hawaii. The cloud-penetrating capabilities of radar provide a rare view of many parts of the island, since the higher elevations are frequently shrouded in clouds. The light blue and yellow areas in the lowlands near the center are sugar cane fields. The three major population centers, Lahaina on the left at the western tip of island, Wailuku left of center, and Kihei in the lower center appear as small yellow, white or purple mottled areas. West Maui volcano, in the lower left, is 1800 meters high (5900 feet) and is considered extinct. The entire eastern half of the island consists of East Maui volcano, which rises to an elevation of 3200 meters (10,500 feet) and features a spectacular crater called Haleakala at its summit. Haleakala Crater was produced by erosion during previous ice ages rather than by volcanic activity, although relatively recent small eruptions have produced the numerous volcanic cones and lava flows that can be seen on the floor of the crater. The most recent eruption took place near the coast at the southwestern end of East Maui volcano in the late 1700s. Such a time frame indicates that East Maui should be considered a dormant, rather than an extinct volcano. A new eruption is therefore possible in the next few hundred years. The multi-wavelength capability of the SIR-C radar also permits differences in the vegetation cover on the middle flanks of East Maui to be identified. Rain forests appear in yellow, while grassland is shown in dark green, pink and blue. Radar images such as this one are being used by scientists to understand volcanic processes and to assess potential threats that future activity may pose to local populations. This image was acquired by Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on April 16, 1994. The image is 73.7 kilometers by 48.7 kilometers (45.7 miles by 30.2 miles) and is centered at 20

  8. Space Radar Image of Canberra, Australia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Australia's capital city, Canberra, is shown in the center of this spaceborne radar image. Images like this can help urban planners assess land use patterns. Heavily developed areas appear in bright patchwork patterns of orange, yellow and blue. Dense vegetation appears bright green, while cleared areas appear in dark blue or black. Located in southeastern Australia, the site of Canberra was selected as the capital in 1901 as a geographic compromise between Sydney and Melbourne. Design and construction of the city began in 1908 under the supervision of American architect Walter Burley-Griffin. Lake Burley-Griffin is located above and to the left of the center of the image. The bright pink area is the Parliament House. The city streets, lined with government buildings, radiate like spokes from the Parliament House. The bright purple cross in the lower left corner of the image is a reflection from one of the large dish-shaped radio antennas at the Tidbinbilla, Canberra Deep Space Network Communication Complex, operated jointly by NASA and the Australian Space Office. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) on April 10, 1994, onboard the space shuttle Endeavour. The image is 28 kilometers by 25 kilometers (17 miles by 15 miles) and is centered at 35.35 degrees south latitude, 149.17 degrees east longitude. North is toward the upper left. The colors are assigned to different radar frequencies and polarizations as follows: red is L-band, horizontally transmitted and received; green is L-band, horizontally transmitted and vertically received; and blue is C-band, horizontally transmitted and vertically received. SIR-C/X-SAR, a joint mission of the German, Italian, and United States space agencies, is part of NASA's Office of Mission to Planet Earth.

  9. Space Radar Image of Victoria, Canada

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This three-frequency spaceborne radar image shows the southern end of Vancouver Island on the west coast of Canada. The white area in the lower right is the city of Victoria, the capital of the province of British Columbia. The three radar frequencies help to distinguish different land use patterns. The bright pink areas are suburban regions, the brownish areas are forested regions, and blue areas are agricultural fields or forest clear-cuts. Founded in 1843 as a fur trading post, Victoria has grown to become one of western Canada's largest commercial centers. In the upper right is San Juan Island, in the state of Washington. The Canada/U.S. border runs through Haro Strait, on the right side of the image, between San Juan Island and Vancouver Island. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) on October 6, 1994, onboard the space shuttle Endeavour. The area shown is 37 kilometers by 42 kilometers (23 miles by 26 miles) and is centered at 48.5 degrees north latitude, 123.3 degrees west longitude. North is toward the upper left. The colors are assigned to different radar frequencies and polarizations as follows: red is L-band horizontally transmitted and received; green is C-band, vertically transmitted and received; and blue is X-band, vertically transmitted and received. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

  10. Forest Profiling with Multiple Observation Interferometric Synthetic Aperture Radar

    NASA Astrophysics Data System (ADS)

    Treuhaft, R. N.; Chapman, B. D.; Dutra, L. V.; Dos Santos, J. R.; Goncalves, F. G.; Mura, J. C.; Freitas, C. D.; Graca, P. M.; Drake, J.

    2006-12-01

    Measurements of the vertical structure of forest vegetation bear on ecosystem state, such as biodiversity, carbon dynamics, and fire susceptibility, and the estimation of forest biomass. Global monitoring of vertical vegetation structure is one of the most important and as yet unrealized goals of forest remote sensing. The Interferometric Synthetic Aperture Radar (InSAR) phase and coherence observations are directly sensitive to the vertical distribution of electromagnetic dielectric in the forest medium. This dielectric distribution in turn depends on vegetation density as a function of the vertical coordinate. Multiple InSAR observations--multiple baseline, multiple frequency, and/or multiple polarization--must be used to uniquely estimate vegetation density profiles. This talk explains the need for multiple observation strategies and the benefits of multiple- baseline, multiple-frequency, and multiple-polarization strategies. Multiple baseline tropical forest profiles from C-band (wavelength=0.056 m) InSAR will be shown, as well as results from L-band (0.25 m) few-baseline observations over La Selva Biological Station, Costa Rica. Both surface-deformation measurements and those relevant to vertical-vegetation structure may result from a single InSAR mission design, provided, for example, that multiple nonzero baselines are flown along with the zero-baseline configuration preferred for deformation. The possibility of mutually improving the accuracy of deformation and structure in a simultaneous- measurement scenario will be discussed. There is also potential synergy with other remote sensing missions, such as the Tandem X InSAR mission, for delivering forest structure.

  11. Non-breaking swell dissipation from synthethic aperture radar

    NASA Astrophysics Data System (ADS)

    Stopa, Justin; Husson, Romain; Ardhuin, Fabrice; Collard, Fabrice; Chapron, Bertrand

    2015-04-01

    Swells have the unique ability to propagate away from their generation region with very little attenuation. Only one study exists in the ocean wave literature that measures the decay rate by following a swell with in-situ measurements along its great circle route. More recently used space-borne synthetic aperture radar (SAR) to measure the attenuation. They estimated the dissipation rate from SAR with a limited number of cases: 11 storms with 22 total events. The present work extrapolates their technique to more events since ENVISAT has collected SAR data from 2002-2012. The dissipation rate is then determined in a two step process. First swell sources are identified from density maps of back-propagated waves at their group velocity along great circles. Next a "point-source" model is assumed and the waves from all directions and frequencies are propagated forward to find matching SAR observations. Relatively small directional bins are used to group observations creating transects from a given swell event. This ensemble of tracks is the basic dataset used to calculate a more statistically robust measure of the dissipation rate. Individual tracks and the swell behavior are explored through this dataset. Our results are in agreement with previous findings and it is verified that swells are very persistent with e-folding scales larger than 20,000 km and they behave nonlinearly as a function of wave frequency. The results are discussed in terms of their implications in spectral wave models as well as identify limitations of the remotely sensed wave spectra. The wind's role on the dissipation rate cannot be determined from this analysis stressing the need for concurrent wind and wave observations.

  12. Seamless Synthetic Aperture Radar Archive for Interferometry Analysis

    NASA Astrophysics Data System (ADS)

    Baker, S.; Meertens, C. M.; Phillips, D. A.; Crosby, C.; Fielding, E. J.; Nicoll, J.; Bryson, G.; Buechler, B.; Baru, C.

    2012-12-01

    The NASA Advancing Collaborative Connections for Earth System Science (ACCESS) Seamless Synthetic Aperture Radar (SAR) Archive (SSARA) project is a 2-year collaboration between UNAVCO/WInSAR, the Alaska Satellite Facility (ASF), the Jet Propulsion Laboratory (JPL), and the San Diego Supercomputer Center (SDSC) to design and implement a seamless distributed access system for SAR data and derived data products (i.e. terrain corrected interferograms). A seamless SAR archive increases the accessibility and the utility of SAR science data to solid Earth and cryospheric science researchers. Building on the established webs services and APIs at UNAVCO and ASF, the SSARA project will provide simple web services tools to seamlessly and effectively exchange and share space- and airborne SAR metadata, archived SAR data, and on-demand derived products between the distributed archives and individual users. Development of standard formats for data products and new QC/QA definitions will be implemented to streamline data usage and enable advanced query capabilities. The new ACCESS-developed tools will help overcome the obstacles of heterogeneous archive access protocols and data formats, data provider access policy constraints, and will also enable interoperability with key information technology development systems such as the NASA/JPL QuakeSim and ARIA projects, which provide higher level resources for geodetic data processing, data assimilation and modeling, and integrative analysis for scientific research and hazards applications. The SSARA project will significantly enhance mature IT capabilities at ASF's NASA-supported DAAC, the GEO Supersites archive, supported operationally by UNAVCO, and UNAVCO's WInSAR and EarthScope SAR archives that are supported by NASA, NSF, and the USGS in close collaboration with ESA/ESRIN.

  13. Space radar image of Mauna Loa, Hawaii

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This image of the Mauna Loa volcano on the Big Island of Hawaii shows the capability of imaging radar to map lava flows and other volcanic structures. Mauna Loa has erupted more than 35 times since the island was first visited by westerners in the early 1800s. The large summit crater, called Mokuaweoweo Caldera, is clearly visible near the center of the image. Leading away from the caldera (towards top right and lower center) are the two main rift zones shown here in orange. Rift zones are areas of weakness within the upper part of the volcano that are often ripped open as new magma (molten rock) approaches the surface at the start of an eruption. The most recent eruption of Mauna Loa was in March and April 1984, when segments of the northeast rift zones were active. If the height of the volcano was measured from its base on the ocean floor instead of from sea level, Mauna Loa would be the tallest mountain on Earth. Its peak (center of the image) rises more than 8 kilometers (5 miles) above the ocean floor. The South Kona District, known for cultivation of macadamia nuts and coffee, can be seen in the lower left as white and blue areas along the coast. North is toward the upper left. The area shown is 41.5 by 75 kilometers (25.7 by 46.5 miles), centered at 19.5 degrees north latitude and 155.6 degrees west longitude. The image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/ X-SAR) aboard the space shuttle Endeavour on its 36th orbit on October 2, 1994. The radar illumination is from the left of the image. The colors in this image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted, vertically received); blue represents the C-band (horizontally transmitted, vertically received). The resulting color combinations in this radar image are caused by differences in surface roughness of the lava flows. Smoother flows

  14. Fine resolution topographic mapping of the Jovian moons: a Ka-band high resolution topographic mapping interferometric synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Madsen, Soren N.; Carsey, Frank D.; Turtle, Elizabeth P.

    2003-01-01

    The topographic data set obtained by MOLA has provided an unprecedented level of information about Mars' geologic features. The proposed flight of JIMO provides an opportunity to accomplish a similar mapping of and comparable scientific discovery for the Jovian moons through us of an interferometric imaging radar analogous to the Shuttle radar that recently generated a new topographic map of Earth. A Ka-band single pass across-track synthetic aperture radar (SAR) interferometer can provide very high resolution surface elevation maps. The concept would use two antennas mounted at the ends of a deployable boom (similar to the Shuttle Radar Topographic Mapper) extended orthogonal to the direction of flight. Assuming an orbit altitude of approximately 100 km and a ground velocity of approximately 1.5 km/sec, horizontal resolutions at the 10 meter level and vertical resolutions at the sub-meter level are possible.

  15. Fine Resolution Topographic Mapping of the Jovian Moons: A Ka-Band High Resolution Topographic Mapping Interferometric Synthetic Aperture Radar

    NASA Technical Reports Server (NTRS)

    Madsen, S. N.; Carsey, F. D.; Turtle, E. P.

    2003-01-01

    The topographic data set obtained by MOLA has provided an unprecedented level of information about Mars' geologic features. The proposed flight of JIMO provides an opportunity to accomplish a similar mapping of and comparable scientific discovery for the Jovian moons through use of an interferometric imaging radar analogous to the Shuttle radar that recently generated a new topographic map of Earth. A Ka-band single pass across-track synthetic aperture radar (SAR) interferometer can provide very high resolution surface elevation maps. The concept would use two antennas mounted at the ends of a deployable boom (similar to the Shuttle Radar Topographic Mapper) extended orthogonal to the direction of flight. Assuming an orbit altitude of approximately 100km and a ground velocity of approximately 1.5 km/sec, horizontal resolutions at the 10 meter level and vertical resolutions at the sub-meter level are possible.

  16. Dynamic metamaterial aperture for microwave imaging

    NASA Astrophysics Data System (ADS)

    Sleasman, Timothy; F. Imani, Mohammadreza; Gollub, Jonah N.; Smith, David R.

    2015-11-01

    We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The aperture consists of an array of complementary, resonant metamaterial elements patterned into the upper conductor of a microstrip line. Each metamaterial element contains two diodes connected to an external control circuit such that the resonance of the metamaterial element can be damped by application of a bias voltage. Through applying different voltages to the control circuit, select subsets of the elements can be switched on to create unique radiation patterns that illuminate the scene. Spatial information of an imaging domain can thus be encoded onto this set of radiation patterns, or measurements, which can be processed to reconstruct the targets in the scene using compressive sensing algorithms. We discuss the design and operation of a metamaterial imaging system and demonstrate reconstructed images with a 10:1 compression ratio. Dynamic metamaterial apertures can potentially be of benefit in microwave or millimeter wave systems such as those used in security screening and through-wall imaging. In addition, feature-specific or adaptive imaging can be facilitated through the use of the dynamic aperture.

  17. Dynamic metamaterial aperture for microwave imaging

    SciTech Connect

    Sleasman, Timothy; Imani, Mohammadreza F.; Gollub, Jonah N.; Smith, David R.

    2015-11-16

    We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The aperture consists of an array of complementary, resonant metamaterial elements patterned into the upper conductor of a microstrip line. Each metamaterial element contains two diodes connected to an external control circuit such that the resonance of the metamaterial element can be damped by application of a bias voltage. Through applying different voltages to the control circuit, select subsets of the elements can be switched on to create unique radiation patterns that illuminate the scene. Spatial information of an imaging domain can thus be encoded onto this set of radiation patterns, or measurements, which can be processed to reconstruct the targets in the scene using compressive sensing algorithms. We discuss the design and operation of a metamaterial imaging system and demonstrate reconstructed images with a 10:1 compression ratio. Dynamic metamaterial apertures can potentially be of benefit in microwave or millimeter wave systems such as those used in security screening and through-wall imaging. In addition, feature-specific or adaptive imaging can be facilitated through the use of the dynamic aperture.

  18. Space Radar Image of Glascow, Missouri

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a false-color L-band image of an area near Glasgow, Missouri, centered at about 39.2 degrees north latitude and 92.8 degrees west longitude. The image was acquired using the L-band radar channel (horizontally transmitted and received and horizontally transmitted/vertically received) polarizations combined. The data were acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on orbit 50 on October 3,1994. The area shown is approximately 37 kilometers by 25 kilometers (23 miles by 16 miles). The radar data, coupled with pre-flood aerial photography and satellite data and post-flood topographic and field data, are being used to evaluate changes associated with levee breaks in landforms, where deposits formed during the widespread flooding in 1993 along the Missouri and Mississippi Rivers. The distinct radar scattering properties of farmland, sand fields and scoured areas will be used to inventory floodplains along the Missouri River and determine the processes by which these areas return to preflood conditions. The image shows one such levee break near Glasgow, Missouri. In the upper center of the radar image, below the bend of the river, is a region covered by several meters of sand, shown as dark regions. West (left) of the dark areas, a gap in the levee tree canopy shows the area where the levee failed. Radar data such as these can help scientists more accurately assess the potential for future flooding in this region and how that might impact surrounding communities. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific

  19. Implementation of swept synthetic aperture imaging

    NASA Astrophysics Data System (ADS)

    Bottenus, Nick; Jakovljevic, Marko; Boctor, Emad; Trahey, Gregg E.

    2015-03-01

    Ultrasound imaging of deep targets is limited by the resolution of current ultrasound systems based on the available aperture size. We propose a system to synthesize an extended effective aperture in order to improve resolution and target detectability at depth using a precisely-tracked transducer swept across the region of interest. A Field II simulation was performed to demonstrate the swept aperture approach in both the spatial and frequency domains. The adaptively beam-formed system was tested experimentally using a volumetric transducer and an ex vivo canine abdominal layer to evaluate the impact of clutter-generating tissue on the resulting point spread function. Resolution was improved by 73% using a 30.8 degree sweep despite the presence of varying aberration across the array with an amplitude on the order of 100 ns. Slight variations were observed in the magnitude and position of side lobes compared to the control case, but overall image quality was not significantly degraded as compared by a simulation based on the experimental point spread function. We conclude that the swept aperture imaging system may be a valuable tool for synthesizing large effective apertures using conventional ultrasound hardware.

  20. Operational Mapping of Soil Moisture Using Synthetic Aperture Radar Data: Application to the Touch Basin (France)

    PubMed Central

    Baghdadi, Nicolas; Aubert, Maelle; Cerdan, Olivier; Franchistéguy, Laurent; Viel, Christian; Martin, Eric; Zribi, Mehrez; Desprats, Jean François

    2007-01-01

    Soil moisture is a key parameter in different environmental applications, such as hydrology and natural risk assessment. In this paper, surface soil moisture mapping was carried out over a basin in France using satellite synthetic aperture radar (SAR) images acquired in 2006 and 2007 by C-band (5.3 GHz) sensors. The comparison between soil moisture estimated from SAR data and in situ measurements shows good agreement, with a mapping accuracy better than 3%. This result shows that the monitoring of soil moisture from SAR images is possible in operational phase. Moreover, moistures simulated by the operational Météo-France ISBA soil-vegetation-atmosphere transfer model in the SIM-Safran-ISBA-Modcou chain were compared to radar moisture estimates to validate its pertinence. The difference between ISBA simulations and radar estimates fluctuates between 0.4 and 10% (RMSE). The comparison between ISBA and gravimetric measurements of the 12 March 2007 shows a RMSE of about 6%. Generally, these results are very encouraging. Results show also that the soil moisture estimated from SAR images is not correlated with the textural units defined in the European Soil Geographical Database (SGDBE) at 1:1000000 scale. However, dependence was observed between texture maps and ISBA moisture. This dependence is induced by the use of the texture map as an input parameter in the ISBA model. Even if this parameter is very important for soil moisture estimations, radar results shown that the textural map scale at 1:1000000 is not appropriate to differentiate moistures zones.

  1. Multi-aperture foveated imaging.

    PubMed

    Carles, Guillem; Chen, Shouqian; Bustin, Nicholas; Downing, James; McCall, Duncan; Wood, Andrew; Harvey, Andrew R

    2016-04-15

    Foveated imaging, such as that evolved by biological systems to provide high angular resolution with a reduced space-bandwidth product, also offers advantages for man-made task-specific imaging. Foveated imaging systems using exclusively optical distortion are complex, bulky, and high cost, however. We demonstrate foveated imaging using a planar array of identical cameras combined with a prism array and superresolution reconstruction of a mosaicked image with a foveal variation in angular resolution of 5.9:1 and a quadrupling of the field of view. The combination of low-cost, mass-produced cameras and optics with computational image recovery offers enhanced capability of achieving large foveal ratios from compact, low-cost imaging systems. PMID:27082366

  2. Space Radar Image of Mississippi Delta

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a radar image of the Mississippi River Delta where the river enters into the Gulf of Mexico along the coast of Louisiana. This multi-frequency image demonstrates the capability of the radar to distinguish different types of wetlands surfaces in river deltas. This image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on October 2, 1995. The image is centered on latitude 29.3 degrees North latitude and 89.28 degrees West longitude. The area shown is approximately 63 kilometers by 43 kilometers (39 miles by 26 miles). North is towards the upper right of the image. As the river enters the Gulf of Mexico, it loses energy and dumps its load of sediment that it has carried on its journey through the mid-continent. This pile of sediment, or mud, accumulates over the years building up the delta front. As one part of the delta becomes clogged with sediment, the delta front will migrate in search of new areas to grow. The area shown on this image is the currently active delta front of the Mississippi. The migratory nature of the delta forms natural traps for oil and the numerous bright spots along the outside of the delta are drilling platforms. Most of the land in the image consists of mud flats and marsh lands. There is little human settlement in this area due to the instability of the sediments. The main shipping channel of the Mississippi River is the broad red stripe running northwest to southeast down the left side of the image. The bright spots within the channel are ships. The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band vertically transmitted, vertically received; green is C-band vertically transmitted, vertically received; blue is X-band vertically transmitted, vertically received. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars

  3. Space Radar Image of Sydney, Australia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This spaceborne radar image is dominated by the metropolitan area of Australia's largest city, Sydney. Sydney Harbour, with numerous coves and inlets, is seen in the upper center of the image, and the roughly circular Botany Bay is shown in the lower right. The downtown business district of Sydney appears as a bright white area just above the center of the image. The Sydney Harbour Bridge is a white line adjacent to the downtown district. The well-known Sydney Opera House is the small, white dot to the right of the bridge. Urban areas appear yellow, blue and brown. The purple areas are undeveloped areas and park lands. Manly, the famous surfing beach, is shown in yellow at the top center of the image. Runways from the Sydney Airport are the dark features that extend into Botany Bay in the lower right. Botany Bay is the site where Captain James Cook first landed his ship, Endeavour, in 1770. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) on April 20, 1994, onboard the space shuttle Endeavour. The area shown is 33 kilometers by 38kilometers (20 miles by 23 miles) and is centered at 33.9 degrees south latitude, 151.2 degrees east longitude. North is toward the upper left. The colors are assigned to different radar frequenciesand polarizations as follows: red is L-band, vertically transmittedand horizontally received; green is C-band, vertically transmitted and horizontally received; and blue is C-band, vertically transmittedand received. SIR-C/X-SAR, a joint mission of the German, Italianand United States space agencies, is part of NASA's Mission to Planet Earth. #####

  4. Mesoscale Near-Surface Wind Speed Variability Mapping with Synthetic Aperture Radar

    PubMed Central

    Young, George; Sikora, Todd; Winstead, Nathaniel

    2008-01-01

    Operationally-significant wind speed variability is often observed within synthetic aperture radar-derived wind speed (SDWS) images of the sea surface. This paper is meant as a first step towards automated distinguishing of meteorological phenomena responsible for such variability. In doing so, the research presented in this paper tests feature extraction and pixel aggregation techniques focused on mesoscale variability of SDWS. A sample of twenty eight SDWS images possessing varying degrees of near-surface wind speed variability were selected to serve as case studies. Gaussian high- and low-pass, local entropy, and local standard deviation filters performed well for the feature extraction portion of the research while principle component analysis of the filtered data performed well for the pixel aggregation. The findings suggest recommendations for future research.

  5. Space Radar Image of Kilauea Volcano, Hawaii

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a deformation map of the south flank of Kilauea volcano on the big island of Hawaii, centered at 19.5 degrees north latitude and 155.25 degrees west longitude. The map was created by combining interferometric radar data -- that is data acquired on different passes of the space shuttle which are then overlayed to obtain elevation information -- acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar during its first flight in April 1994 and its second flight in October 1994. The area shown is approximately 40 kilometers by 80 kilometers (25 miles by 50 miles). North is toward the upper left of the image. The colors indicate the displacement of the surface in the direction that the radar instrument was pointed (toward the right of the image) in the six months between images. The analysis of ground movement is preliminary, but appears consistent with the motions detected by the Global Positioning System ground receivers that have been used over the past five years. The south flank of the Kilauea volcano is among the most rapidly deforming terrains on Earth. Several regions show motions over the six-month time period. Most obvious is at the base of Hilina Pali, where 10 centimeters (4 inches) or more of crustal deformation can be seen in a concentrated area near the coastline. On a more localized scale, the currently active Pu'u O'o summit also shows about 10 centimeters (4 inches) of change near the vent area. Finally, there are indications of additional movement along the upper southwest rift zone, just below the Kilauea caldera in the image. Deformation of the south flank is believed to be the result of movements along faults deep beneath the surface of the volcano, as well as injections of magma, or molten rock, into the volcano's 'plumbing' system. Detection of ground motions from space has proven to be a unique capability of imaging radar technology. Scientists hope to use deformation data acquired by SIR-C/X-SAR and future imaging

  6. Rapid, Repeat-sample Monitoring of Crustal Deformations and Environmental Phenomena with the Uninhabited Aerial Vehicle Synthetic Aperture Radar

    NASA Technical Reports Server (NTRS)

    Smith, Robert C.

    2006-01-01

    The Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) is a precision repeat-pass Interferometric Synthetic Aperture Radar (InSAR) mission being developed by the Jet Propulsion Laboratory and the Dryden Flight Research Center in support of NASA s Science Mission Directorate. UAVSAR's unique ability to fly a repeatable flight path, along with an electronically steerable array, allows interferometric data to be obtained with accuracies measured in millimeters. Deploying the radar on an airborne platform will also allow for radar images to be collected and compared with images from the same area taken hours or even years later - providing for long-term trending and near real-time notification of changes and deformations. UAVSAR s data processing algorithms will provide for near-real time data reduction providing disaster planning and response teams with highly accurate data to aid in the prediction of, and response to, natural phenomena. UAVSAR data can be applied to increasing our understanding of the processes behind solid earth, cryosphere, carbon cycle and other areas of interest in earth science. Technologies developed for UAVSAR may also be applicable to a future earth-orbiting InSAR mission and possibly for missions to the Moon or Mars. The UAVSAR is expected to fly on a Gulfstream III aircraft this winter, followed by a flight test program lasting until the second half of 2007. Following radar calibration and data reduction activities, the platform will be ready for science users in the summer of 2008.

  7. Two antenna, two pass interferometric synthetic aperture radar

    DOEpatents

    Martinez, Ana; Doerry, Armin W.; Bickel, Douglas L.

    2005-06-28

    A multi-antenna, multi-pass IFSAR mode utilizing data driven alignment of multiple independent passes can combine the scaling accuracy of a two-antenna, one-pass IFSAR mode with the height-noise performance of a one-antenna, two-pass IFSAR mode. A two-antenna, two-pass IFSAR mode can accurately estimate the larger antenna baseline from the data itself and reduce height-noise, allowing for more accurate information about target ground position locations and heights. The two-antenna, two-pass IFSAR mode can use coarser IFSAR data to estimate the larger antenna baseline. Multi-pass IFSAR can be extended to more than two (2) passes, thereby allowing true three-dimensional radar imaging from stand-off aircraft and satellite platforms.

  8. Analyses of Multi-Year Synthetic Aperture Radar Imagery of Dry-Fallen Intertidal Flats

    NASA Astrophysics Data System (ADS)

    Gade, M.; Melchionna, S.; Kemme, L.

    2015-04-01

    We analyzed a great deal of high-resolution Synthetic Aperture Radar (SAR) data of dry-fallen intertidal flats in the German Wadden Sea with respect to the imaging of sediments, macrophytes, and mussels. TerraSAR-X and Radarsat-2 images of five test areas along the German North Sea coast acquired between 2008 and 2013 form the basis for the present investigation and are used to demonstrate that pairs of SAR images, if combined through basic algebraic operations, can already provide useful indicators for morphological changes and for bivalve (oyster and mussel) beds. Depending on the type of sediment, but also on the water level and on environmental conditions (wind speed) exposed sediments may show up on SAR imagery as areas of enhanced, or reduced, radar backscattering. The (multi-temporal) analysis of series of such images allows for the detection of mussel beds, and our results show evidence that also single-acquisition, multi-polarization SAR imagery can be used for that purpose.

  9. Radar image San Francisco Bay Area, California

    NASA Technical Reports Server (NTRS)

    2000-01-01

    preliminary nature of this image product. These artifacts will be removed after further data processing.

    This image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11,2000. SRTM uses the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission is designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian Space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.

    Size: 38 km (24 miles) by 71 km (44 miles) Location: 37.7 deg. North lat., 122.2 deg. West lon. Orientation: North to the upper right Original Data Resolution: 30 meters (99 feet) Date Acquired: February 16, 2000

  10. Mississippi Delta, Radar Image with Colored Height

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Click on the image for the animation

    About the animation: This simulated view of the potential effects of storm surge flooding on Lake Pontchartrain and the New Orleans area was generated with data from the Shuttle Radar Topography Mission. Although it is protected by levees and sea walls against storm surges of 18 to 20 feet, much of the city is below sea level, and flooding due to storm surges caused by major hurricanes is a concern. The animation shows regions that, if unprotected, would be inundated with water. The animation depicts flooding in one-meter increments.

    About the image: The geography of the New Orleans and Mississippi delta region is well shown in this radar image from the Shuttle Radar Topography Mission. In this image, bright areas show regions of high radar reflectivity, such as from urban areas, and elevations have been coded in color using height data also from the mission. Dark green colors indicate low elevations, rising through yellow and tan, to white at the highest elevations.

    New Orleans is situated along the southern shore of Lake Pontchartrain, the large, roughly circular lake near the center of the image. The line spanning the lake is the Lake Pontchartrain Causeway, the world's longest over water highway bridge. Major portions of the city of New Orleans are below sea level, and although it is protected by levees and sea walls, flooding during storm surges associated with major hurricanes is a significant concern.

    Data used in this image were acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. The mission used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar that flew twice on the Space Shuttle Endeavour in 1994. The Shuttle Radar Topography Mission was designed to collect 3-D measurements of the Earth's surface. To collect the 3-D data

  11. Space Radar Image of Kiluchevskoi, Volcano, Russia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is an image of the area of Kliuchevskoi volcano, Kamchatka, Russia, which began to erupt on September 30, 1994. Kliuchevskoi is the blue triangular peak in the center of the image, towards the left edge of the bright red area that delineates bare snow cover. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on its 88th orbit on October 5, 1994. The image shows an area approximately 75 kilometers by 100 kilometers (46 miles by 62 miles) that is centered at 56.07 degrees north latitude and 160.84 degrees east longitude. North is toward the bottom of the image. The radar illumination is from the top of the image. The Kamchatka volcanoes are among the most active volcanoes in the world. The volcanic zone sits above a tectonic plate boundary, where the Pacific plate is sinking beneath the northeast edge of the Eurasian plate. The Endeavour crew obtained dramatic video and photographic images of this region during the eruption, which will assist scientists in analyzing the dynamics of the recent activity. The colors in this image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted and vertically received); blue represents the C-band (horizontally transmitted and vertically received). In addition to Kliuchevskoi, two other active volcanoes are visible in the image. Bezymianny, the circular crater above and to the right of Kliuchevskoi, contains a slowly growing lava dome. Tolbachik is the large volcano with a dark summit crater near the upper right edge of the red snow covered area. The Kamchatka River runs from right to left across the bottom of the image. The current eruption of Kliuchevskoi included massive ejections of gas, vapor and ash, which reached altitudes of 15,000 meters (50,000 feet). Melting snow mixed with volcanic ash triggered mud flows on the

  12. Space Radar Image of Houston, Texas

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This image of Houston, Texas, shows the amount of detail that is possible to obtain using spaceborne radar imaging. Images such as this -- obtained by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) flying aboard the space shuttle Endeavor last fall -- can become an effective tool for urban planners who map and monitor land use patterns in urban, agricultural and wetland areas. Central Houston appears pink and white in the upper portion of the image, outlined and crisscrossed by freeways. The image was obtained on October 10, 1994, during the space shuttle's 167th orbit. The area shown is 100 kilometers by 60 kilometers (62 miles by 38 miles) and is centered at 29.38 degrees north latitude, 95.1 degrees west longitude. North is toward the upper left. The pink areas designate urban development while the green-and blue-patterned areas are agricultural fields. Black areas are bodies of water, including Galveston Bay along the right edge and the Gulf of Mexico at the bottom of the image. Interstate 45 runs from top to bottom through the image. The narrow island at the bottom of the image is Galveston Island, with the city of Galveston at its northeast (right) end. The dark cross in the upper center of the image is Hobby Airport. Ellington Air Force Base is visible below Hobby on the other side of Interstate 45. Clear Lake is the dark body of water in the middle right of the image. The green square just north of Clear Lake is Johnson Space Center, home of Mission Control and the astronaut training facilities. The black rectangle with a white center that appears to the left of the city center is the Houston Astrodome. The colors in this image were obtained using the follow radar channels: red represents the L-band (horizontally transmitted, vertically received); green represents the C-band (horizontally transmitted, vertically received); blue represents the C-band (horizontally transmitted and received). Spaceborne Imaging Radar

  13. Space Radar Image of Mammoth Mountain, California

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This false-color composite radar image of the Mammoth Mountain area in the Sierra Nevada Mountains, California, was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar aboard the space shuttle Endeavour on its 67th orbit on October 3, 1994. The image is centered at 37.6 degrees north latitude and 119.0 degrees west longitude. The area is about 39 kilometers by 51 kilometers (24 miles by 31 miles). North is toward the bottom, about 45 degrees to the right. In this image, red was created using L-band (horizontally transmitted/vertically received) polarization data; green was created using C-band (horizontally transmitted/vertically received) polarization data; and blue was created using C-band (horizontally transmitted and received) polarization data. Crawley Lake appears dark at the center left of the image, just above or south of Long Valley. The Mammoth Mountain ski area is visible at the top right of the scene. The red areas correspond to forests, the dark blue areas are bare surfaces and the green areas are short vegetation, mainly brush. The purple areas at the higher elevations in the upper part of the scene are discontinuous patches of snow cover from a September 28 storm. New, very thin snow was falling before and during the second space shuttle pass. In parallel with the operational SIR-C data processing, an experimental effort is being conducted to test SAR data processing using the Jet Propulsion Laboratory's massively parallel supercomputing facility, centered around the Cray Research T3D. These experiments will assess the abilities of large supercomputers to produce high throughput Synthetic Aperture Radar processing in preparation for upcoming data-intensive SAR missions. The image released here was produced as part of this experimental effort. Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR)are part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed

  14. Synthetic aperture imaging in ultrasound calibration

    NASA Astrophysics Data System (ADS)

    Ameri, Golafsoun; Baxter, John S. H.; McLeod, A. Jonathan; Jayaranthe, Uditha L.; Chen, Elvis C. S.; Peters, Terry M.

    2014-03-01

    Ultrasound calibration allows for ultrasound images to be incorporated into a variety of interventional applica­ tions. Traditional Z- bar calibration procedures rely on wired phantoms with an a priori known geometry. The line fiducials produce small, localized echoes which are then segmented from an array of ultrasound images from different tracked probe positions. In conventional B-mode ultrasound, the wires at greater depths appear blurred and are difficult to segment accurately, limiting the accuracy of ultrasound calibration. This paper presents a novel ultrasound calibration procedure that takes advantage of synthetic aperture imaging to reconstruct high resolution ultrasound images at arbitrary depths. In these images, line fiducials are much more readily and accu­ rately segmented, leading to decreased calibration error. The proposed calibration technique is compared to one based on B-mode ultrasound. The fiducial localization error was improved from 0.21mm in conventional B-mode images to 0.15mm in synthetic aperture images corresponding to an improvement of 29%. This resulted in an overall reduction of calibration error from a target registration error of 2.00mm to 1.78mm, an improvement of 11%. Synthetic aperture images display greatly improved segmentation capabilities due to their improved resolution and interpretability resulting in improved calibration.

  15. Aperture synthesis imaging from the moon

    NASA Technical Reports Server (NTRS)

    Burns, Jack O.

    1991-01-01

    Four candidate imaging aperture synthesis concepts are described for possible emplacement on the moon beginning in the next decade. These include an optical interferometer with 10 microarcsec resolution, a submillimeter array with 6 milliarcsec resolution, a moon-earth VLBI experiment, and a very low frequency interferometer in lunar orbit.

  16. Space Radar Image of Oetzal, Austria

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a digital elevation model that was geometrically coded directly onto an X-band seasonal change image of the Oetztal supersite in Austria. The image is centered at 46.82 degrees north latitude and 10.79 degrees east longitude. This image is located in the Central Alps at the border between Switzerland, Italy and Austria, 50 kilometers (31 miles) southwest of Innsbruck. It was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture aboard the space shuttle Endeavour on April 14, 1994 and on October 5, 1994. It was produced by combining data from these two different data sets. Data obtained in April is green; data obtained in October appears in red and blue, and was used as an enhancement based on the ratio of the two data sets. Areas with a decrease in backscatter from April to October appear in light blue (cyan), such as the large Gepatschferner glacier seen at the left of the image center, and most of the other glaciers in this view. A light blue hue is also visible at the east border of the dark blue Lake Reschensee at the upper left side. This shows a significant rise in the water level. Magenta represents areas with an increase of backscatter from April 10 to October 5. Yellow indicates areas with high radar signal response during both passes, such as the mountain slopes facing the radar. Low radar backscatter signals refer to smooth surface (lakes) or radar grazing areas to radar shadow areas, seen in the southeast slopes. The area is approximately 29 kilometers by 21 kilometers (18 miles by 13.5 miles). The summit of the main peaks reaches elevations of 3,500 to 3,768 meters (xx feet to xx feet)above sea level. The test site's core area is the glacier region of Venter Valley, which is one of the most intensively studied areas for glacier research in the world. Research in Venter Valley (below center)includes studies of glacier dynamics, glacier-climate regions, snowpack conditions and glacier hydrology. About 25 percent of the core test

  17. Focus of attention for millimeter and ultra wideband synthetic aperture radar imagery

    NASA Astrophysics Data System (ADS)

    Yen, Li-Kang

    The major goal of this research is to develop efficient detectors for Synthetic Aperture Radar (SAR) images, exploiting the reflectivity characteristics of targets in different radar types. Target detection is a signal processing problem whereby one attempts to detect a stationary target embedded in background clutter while minimizing the false alarm probability. In radar signal processing, the better resolution provided by the Millimeter Wave (MMW) SAR enhances the detectability of small targets. As radar technology evolves, the newly developed Ultra Wideband (UWB) SAR provides better penetration capabilities to locate concealed targets in foliage. In this thesis we demonstrate that local intensity kernel tests can be formulated based on the generalized likelihood ratio test (GLRT), while preserving constant false alarm rate (CFAR) characteristics. Both the widely used two-parameter CFAR and the g -CFAR can be viewed as special cases of the local intensity tests with different intensity kernels. It is demonstrated that the first-order Gamma kernel is a good approximation for the principal eigenvector of the projected radial intensity of targets, which provides the optimal matching intensity kernel. This also explains the better performance of the g -CFAR detector over the two parameter CFAR detector. We also developed different CFAR subspace detectors for UWB images, utilizing a Laguerre function subspace. The driven response produced by natural clutter degrades the performance of these subspace detectors. In addition to the driven response, the distinguishing feature of metallic targets in UWB is the resonance response. Therefore, we further propose a two-stage detection scheme: g -CFAR detector followed by the quadratic Laguerre discriminator (QLD). We evaluate every detector and discriminator using ROC curves in a large area (about 2 km2) of imagery. The combined g -CFAR and quadratic Laguerre discriminator improve the simple Laguerre subspace detector more

  18. Space Radar Image of North Sea, Germany

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is an X-band image of an oil slick experiment conducted in the North Sea, Germany. The image is centered at 54.58 degrees north latitude and 7.48 degrees east longitude. This image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on October 6, 1994, during the second flight of the spaceborne radar. The experiment was designed to differentiate between petroleum oil spills and natural slicks floating on the sea surface. Two types of petroleum oil and six types of oils resembling natural sea surface slicks were poured on the sea surface from ships and a helicopter just before the space shuttle flew over the region. At the bottom of the image is the Sylt peninsula, a famous holiday resort. Twenty-six gallons (100 liters) of diesel oil was dissipated due to wave action before the shuttle reached the site. The oil spill seen at the uppermost part of the image is about 105 gallons (400 liters) of heavy heating oil and the largest spill is about 58 gallons (220 liters) of oleyl alcohol, resembling a 'natural oil' like the remaining five spills used to imitate natural slicks that have occurred offshore from various states. The volume of these other oils spilled on the ocean surface during the five experimental spills varied from 16 gallons to 21 gallons (60 liters to 80 liters). The distance between neighboring spills was about half a mile (800 meters) at the most. The largest slick later thinned out to monomolecular sheets of about 10 microns, which is the dimension of a molecule. Oceanographers found that SIR-C/X-SAR was able to clearly distinguish the oil slicks from algae products dumped nearby. Preliminary indications are that various types of slicks may be distinguished, especially when other radar wavelengths are included in the analysis. Radar imaging of the world's oceans on a continuing basis may allow oceanographers in the future to detect and clean up oil spills much more

  19. The AdaptiSPECT Imaging Aperture

    PubMed Central

    Chaix, Cécile; Moore, Jared W.; Van Holen, Roel; Barrett, Harrison H.; Furenlid, Lars R.

    2015-01-01

    In this paper, we present the imaging aperture of an adaptive SPECT imaging system being developed at the Center for Gamma Ray Imaging (AdaptiSPECT). AdaptiSPECT is designed to automatically change its configuration in response to preliminary data, in order to improve image quality for a particular task. In a traditional pinhole SPECT imaging system, the characteristics (magnification, resolution, field of view) are set by the geometry of the system, and any modification can be accomplished only by manually changing the collimator and the distance of the detector to the center of the field of view. Optimization of the imaging system for a specific task on a specific individual is therefore difficult. In an adaptive SPECT imaging system, on the other hand, the configuration can be conveniently changed under computer control. A key component of an adaptive SPECT system is its aperture. In this paper, we present the design, specifications, and fabrication of the adaptive pinhole aperture that will be used for AdaptiSPECT, as well as the controls that enable autonomous adaptation. PMID:27019577

  20. Diffraction contrast imaging using virtual apertures.

    PubMed

    Gammer, Christoph; Burak Ozdol, V; Liebscher, Christian H; Minor, Andrew M

    2015-08-01

    Two methods on how to obtain the full diffraction information from a sample region and the associated reconstruction of images or diffraction patterns using virtual apertures are demonstrated. In a STEM-based approach, diffraction patterns are recorded for each beam position using a small probe convergence angle. Similarly, a tilt series of TEM dark-field images is acquired. The resulting datasets allow the reconstruction of either electron diffraction patterns, or bright-, dark- or annular dark-field images using virtual apertures. The experimental procedures of both methods are presented in the paper and are applied to a precipitation strengthened and creep deformed ferritic alloy with a complex microstructure. The reconstructed virtual images are compared with conventional TEM images. The major advantage is that arbitrarily shaped virtual apertures generated with image processing software can be designed without facing any physical limitations. In addition, any virtual detector that is specifically designed according to the underlying crystal structure can be created to optimize image contrast. PMID:25840371

  1. Space Radar Image of Sudan Collision Zone

    NASA Technical Reports Server (NTRS)

    1994-01-01

    received; green is L-band, horizontally transmitted and vertically received; and blue is C-band, horizontally transmitted and vertically received. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) when it flew aboard the space shuttle Endeavour in April 1994. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth.

  2. Study of a Winter Monsoon Front and a Squall Line over the South China Sea by Synergetic Use of Synthetic Aperture and Weather Radar Data

    NASA Astrophysics Data System (ADS)

    Alpers, Werner; Cheng, Choming; Chan, Pakwai; Wong, Waikin; Dagestad, Knut-Frode

    2013-01-01

    Synthetic aperture radar (SAR) images acquired by the Advanced Synthetic Aperture Radar (ASAR) onboard the European Envisat satellite and weather radar images of the Hong Kong Observatory (HKO) are used to study a winter monsoon front and a squall line over the South China Sea (SCS). The atmospheric front was generated by a freshening of the northeast monsoon caused by the merging of two high pressure areas over the Chinese Continent. The high-resolution SAR image reveals finescale structures of the front which cannot be obtained by other spaceborne sensors. This front is further investigated by using other satellite data and by comparing the observational data with model data. Squall lines are lines of organized convective rain cells accompanied by wind shear and high wind gusts. It is shown that the synergetic use of high-resolution SAR and weather radar data provides a comprehensive view of the three-dimensional wind flow associated with the squall line.

  3. Space Radar Image of Manaus, Brazil

    NASA Technical Reports Server (NTRS)

    1994-01-01

    These two false-color images of the Manaus region of Brazil in South America were acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar on board the space shuttle Endeavour. The image at left was acquired on April 12, 1994, and the image at right was acquired on October 3, 1994. The area shown is approximately 8 kilometers by 40 kilometers (5 miles by 25 miles). The two large rivers in this image, the Rio Negro (at top) and the Rio Solimoes (at bottom), combine at Manaus (west of the image) to form the Amazon River. The image is centered at about 3 degrees south latitude and 61 degrees west longitude. North is toward the top left of the images. The false colors were created by displaying three L-band polarization channels: red areas correspond to high backscatter, horizontally transmitted and received, while green areas correspond to high backscatter, horizontally transmitted and vertically received. Blue areas show low returns at vertical transmit/receive polarization; hence the bright blue colors of the smooth river surfaces can be seen. Using this color scheme, green areas in the image are heavily forested, while blue areas are either cleared forest or open water. The yellow and red areas are flooded forest or floating meadows. The extent of the flooding is much greater in the April image than in the October image and appears to follow the 10-meter (33-foot) annual rise and fall of the Amazon River. The flooded forest is a vital habitat for fish, and floating meadows are an important source of atmospheric methane. These images demonstrate the capability of SIR-C/X-SAR to study important environmental changes that are impossible to see with optical sensors over regions such as the Amazon, where frequent cloud cover and dense forest canopies block monitoring of flooding. Field studies by boat, on foot and in low-flying aircraft by the University of California at Santa Barbara, in collaboration with Brazil's Instituto Nacional de Pesguisas

  4. Synthetic aperture radar operator tactical target acquisition research

    NASA Technical Reports Server (NTRS)

    Hershberger, M. L.; Craig, D. W.

    1978-01-01

    A radar target acquisition research study was conducted to access the effects of two levels of 13 radar sensor, display, and mission parameters on operator tactical target acquisition. A saturated fractional-factorial screening design was employed to examine these parameters. Data analysis computed ETA squared values for main and second-order effects for the variables tested. Ranking of the research parameters in terms of importance to system design revealed four variables (radar coverage, radar resolution/multiple looks, display resolution, and display size) accounted for 50 percent of the target acquisition probability variance.

  5. Agile multiple aperture imager receiver development

    NASA Astrophysics Data System (ADS)

    Lees, David E. B.; Dillon, Robert F.

    1990-02-01

    A variety of unconventional imaging schemes have been investigated in recent years that rely on small, unphased optical apertures (subaperture) to measure properties of an incoming optical wavefront and recover images of distant objects without using precisely figured, large aperture optical elements. Such schemes offer several attractive features. They provide the potential to create very lare effective aperture that are expandable over time and can be launched into space in small pieces. Since the subapertures are identical in construction, they may be mass producible at potentially low cost. A preliminary design for a practical low cost optical receiver is presented. The multiple aperture design has high sensitivity, wide field-of-view, and is lightweight. A combination of spectral, temporal, and spatial background suppression are used to achieve daytime operation at low signal levels. Modular packaging to make the number of receiver subapertures conveniently scalable is also presented. The design is appropriate to a ground-base proof-of-concept experiment for long range active speckle imaging.

  6. Space Radar Image of Cape Cod, Massachusetts

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This spaceborne radar image shows the famous 'hook' of Cape Cod, Massachusetts. The Cape, which juts out into the Atlantic Ocean about 100 kilometers (62 miles) southeast of Boston, actually consists of sandy debris left behind by the great continental ice sheets when they last retreated from southern New England about 20,000 years ago. Today's landscape consists of sandy forests, fields of scrub oak and other bushes and grasses, salt marshes, freshwater ponds, as well as the famous beaches and sand dunes. In this image, thickly forested areas appear green, marshes are dark blue, ponds and sandy areas are black, and developed areas are mostly pink. The dark L-shape in the lower center is the airport runways in Hyannis, the Cape's largest town. The dark X-shape left of the center is Otis Air Force Base. The Cape Cod Canal, above and left of center, connects Buzzards Bay on the left with Cape Cod Bay on the right. The northern tip of the island of Martha's Vineyard is seen in the lower left. The tip of the Cape, in the upper right, includes the community of Provincetown, which appears pink, and the protected National Seashore areas of sand dunes that parallel the Atlantic coast east of Provincetown. Scientists are using radar images like this one to study delicate coastal environments and the effects of human activities on the ecosystem and landscape. This image was acquired by Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour on April 15, 1994. The image is 81.7 kilometers by 43.1 kilometers (50.7 miles by 26.7 miles) and is centered at 41.8 degrees north latitude, 70.3 degrees west longitude. North is toward the upper right. The colors are assigned to different radar frequencies and polarizations of the radar as follows: red is L-band, horizontally transmitted and received; green is C-band, horizontally transmitted, vertically received; and blue is C-band, horizontally transmitted and received. SIR

  7. Spaceborne radar observations: A guide for Magellan radar-image analysis

    NASA Technical Reports Server (NTRS)

    Ford, J. P.; Blom, R. G.; Crisp, J. A.; Elachi, Charles; Farr, T. G.; Saunders, R. Stephen; Theilig, E. E.; Wall, S. D.; Yewell, S. B.

    1989-01-01

    Geologic analyses of spaceborne radar images of Earth are reviewed and summarized with respect to detecting, mapping, and interpreting impact craters, volcanic landforms, eolian and subsurface features, and tectonic landforms. Interpretations are illustrated mostly with Seasat synthetic aperture radar and shuttle-imaging-radar images. Analogies are drawn for the potential interpretation of radar images of Venus, with emphasis on the effects of variation in Magellan look angle with Venusian latitude. In each landform category, differences in feature perception and interpretive capability are related to variations in imaging geometry, spatial resolution, and wavelength of the imaging radar systems. Impact craters and other radially symmetrical features may show apparent bilateral symmetry parallel to the illumination vector at low look angles. The styles of eruption and the emplacement of major and minor volcanic constructs can be interpreted from morphological features observed in images. Radar responses that are governed by small-scale surface roughness may serve to distinguish flow types, but do not provide unambiguous information. Imaging of sand dunes is rigorously constrained by specific angular relations between the illumination vector and the orientation and angle of repose of the dune faces, but is independent of radar wavelength. With a single look angle, conditions that enable shallow subsurface imaging to occur do not provide the information necessary to determine whether the radar has recorded surface or subsurface features. The topographic linearity of many tectonic landforms is enhanced on images at regional and local scales, but the detection of structural detail is a strong function of illumination direction. Nontopographic tectonic lineaments may appear in response to contrasts in small-surface roughness or dielectric constant. The breakpoint for rough surfaces will vary by about 25 percent through the Magellan viewing geometries from low to high

  8. Space Radar Image of Vesuvius, Italy

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Mt. Vesuvius, one of the best known volcanoes in the world primarily for the eruption that buried the Roman city of Pompeii, is shown in the center of this radar image. The central cone of Vesuvius is the dark purple feature in the center of the volcano. This cone is surrounded on the northern and eastern sides by the old crater rim, called Mt. Somma. Recent lava flows are the pale yellow areas on the southern and western sides of the cone. Vesuvius is part of a large volcanic zone which includes the Phalagrean Fields, the cluster of craters seen along the left side of the image. The Bay of Naples, on the left side of the image, is separated from the Gulf of Salerno, in the lower left, by the Sorrento Peninsula. Dense urban settlement can be seen around the volcano. The city of Naples is above and to the left of Vesuvius; the seaport of the city can be seen in the top of the bay. Pompeii is located just below the volcano on this image. The rapid eruption in 79 A.D. buried the victims and buildings of Pompeii under several meters of debris and killed more than 2,000 people. Due to the violent eruptive style and proximity to populated areas, Vesuvius has been named by the international scientific community as one of fifteen Decade Volcanoes which are being intensively studied during the 1990s. The image is centered at 40.83 degrees North latitude, 14.53 degrees East longitude. It shows an area 100 kilometers by 55 kilometers (62 miles by 34 miles.) This image was acquired on April 15, 1994 by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the Space Shuttle Endeavour. SIR-C/X-SAR, a joint mission of the German, Italian and the United States space agencies, is part of NASA's Mission to Planet Earth.

  9. Space Radar Image of Flevoland, Netherlands

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a three-frequency false color image of Flevoland, The Netherlands, centered at 52.4 degrees north latitude, 5.4 degrees east longitude. This image was acquired by the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard space shuttle Endeavour on April 14, 1994. It was produced by combining data from the X-band, C-band and L-band radars. The area shown is approximately 25 kilometers by 28 kilometers (15-1/2 by 17-1/2 miles). Flevoland, which fills the lower two-thirds of the image, is a very flat area that is made up of reclaimed land that is used for agriculture and forestry. At the top of the image, across the canal from Flevoland, is an older forest shown in red; the city of Harderwijk is shown in white on the shore of the canal. At this time of the year, the agricultural fields are bare soil, and they show up in this image in blue. The changes in the brightness of the blue areas are equal to the changes in roughness. The dark blue areas are water and the small dots in the canal are boats. This SIR-C/X-SAR supersite is being used for both calibration and agricultural studies. Several soil and crop ground-truth studies will be conducted during the shuttle flight. In addition, about 10calibration devices and 10 corner reflectors have been deployed to calibrate and monitor the radar signal. One of these transponders can be seen as a bright star in the lower right quadrant of the image. This false-color image was made using L-band total power in the red channel, C-band total power in the green channel, and X-band VV polarization in the blue channel. Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be

  10. Space Radar Image of Kliuchevskoi, Russia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is an X-band seasonal image of the Maly Semlyachik volcano, which is part of the Karymsky volcano group on Kamchatka peninsula, Russia. The image is centered at 54.2 degrees north latitude and 159.6 degrees east longitude. This image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on April 9, 1994, during the first flight of the radar system, and on September 30, 1994, during the second flight. The image channels have been assigned the following colors: red corresponds to data acquired on April 9; green corresponds to data acquired on September 30; and blue corresponds to the ratio between data from April 9 and September 30, 1994. Kamchatka is twice as large as England, Scotland and Wales combined and is home to approximately 470,000 residents. The region is characterized by a chain of volcanoes stretching 800 kilometers (500 miles) across the countryside. Many of the volcanoes, including the active Maly Semlyachik volcano in this image, have erupted during this century. But the most active period in creating the three characteristic craters of this volcano goes back 20,000, 12,000 and 2,000 years ago. The highest summit of the oldest crater reaches about 1,560 meters (1,650 feet). The radar images reveal the geological structures of craters and lava flows in order to improve scientists' knowledge of these sometimes vigorously active volcanoes. This seasonal composite also highlights the ecological differences that have occurred between April and October 1994. In April the whole area was snow-covered and, at the coast, an ice sheet extended approximately 5 kilometers (3 miles) into the sea. The area shown surrounding the volcano is covered by low vegetation much like scrub. Kamchatka also has extensive forests, which belong to the northern frontier of Taiga, the boreal forest ecosystem. This region plays an important role in the world's carbon cycle. Trees require 60 years to

  11. Observation of wave refraction at an ice edge by synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Liu, Antony K.; Vachon, Paris W.; Peng, Chih Y.

    1991-01-01

    In this note the refraction of waves at the ice edge is studied by using aircraft synthesis aperture radar (SAR). Penetration of a dominant swell from open ocean into the ice cover was observed by SAR during the Labrador Ice Margin Experiment (LIMEX), conducted on the marginal ice zone (MIZ) off the east coast of Newfoundland, Canada, in March 1987. At an ice edge with a large curvature, the dominant swell component disappeared locally in the SAR imagery. Six subscenes of waves in the MIZ from the SAR image have been processed, revealing total reflection, refraction, and energy reduction of the ocean waves by the ice cover. The observed variations of wave spectra from SAR near the ice edge are consistent with the model prediction of wave refraction at the ice edge due to the change of wave dispersion relation in ice developed by Liu and Mollo-Christensen (1988).

  12. On the importance of path for phase unwrapping in synthetic aperture radar interferometry.

    PubMed

    Osmanoglu, Batuhan; Dixon, Timothy H; Wdowinski, Shimon; Cabral-Cano, Enrique

    2011-07-01

    Phase unwrapping is a key procedure in interferometric synthetic aperture radar studies, translating ambiguous phase observations to topography, and surface deformation estimates. Some unwrapping algorithms are conducted along specific paths based on different selection criteria. In this study, we analyze six unwrapping paths: line scan, maximum coherence, phase derivative variance, phase derivative variance with branch-cut, second-derivative reliability, and the Fisher distance. The latter is a new path algorithm based on Fisher information theory, which combines the phase derivative with the expected variance to get a more robust path, potentially performing better than others in the case of low image quality. In order to compare only the performance of the paths, the same unwrapping function (phase derivative integral) is used. Results indicate that the Fisher distance algorithm gives better results in most cases. PMID:21743520

  13. Coherence estimation in synthetic aperture radar data based on speckle noise modeling.

    PubMed

    López-Martínez, Carlos; Pottier, Eric

    2007-02-01

    In the past we proposed a multidimensional speckle noise model to which we now include systematic phase variation effects. This extension makes it possible to define what is believed to be a novel coherence model able to identify the different sources of bias when coherence is estimated on multidimensional synthetic radar aperture (SAR) data. On the one hand, low coherence biases are basically due to the complex additive speckle noise component of the Hermitian product of two SAR images. On the other hand, the availability of the coherence model permits us to quantify the bias due to topography when multilook filtering is considered, permitting us to establish the conditions upon which information may be estimated independently of topography. Based on the coherence model, two coherence estimation approaches, aiming to reduce the different biases, are proposed. Results with simulated and experimental polarimetric and interferometric SAR data illustrate and validate both, the coherence model and the coherence estimation algorithms. PMID:17230249

  14. Imaging correlography with sparse collecting apertures

    NASA Astrophysics Data System (ADS)

    Idell, Paul S.; Fienup, J. R.

    1987-01-01

    This paper investigates the possibility of implementing an imaging correlography system with sparse arrays of intensity detectors. The theory underlying the image formation process for imaging correlography is reviewed, emphasizing the spatial filtering effects that sparse collecting apertures have on the reconstructed imagery. Image recovery with sparse arrays of intensity detectors through the use of computer experiments in which laser speckle measurements are digitally simulated is then demonstrated. It is shown that the quality of imagery reconstructed using this technique is visibly enhanced when appropriate filtering techniques are applied. A performance tradeoff between collecting array redundancy and the number of speckle pattern measurements is briefly discussed.

  15. Space Radar Image of Altona, Manitoba, Canada

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is an X-band seasonal image of the Altona test site in Manitoba, Canada, about 80 kilometers (50 miles) south of Winnipeg. The image is centered at approximately 49 degrees north latitude and 97.5 degrees west longitude. This image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on April 11, 1994, during the first flight of the radar system, and on October 2, 1994, during the second flight of SIR-C/X-SAR. The image channels have the following color assignments: red represents data acquired on April 11, 1994; green represents data acquired on October 2, 1994; blue represents the ratio of the two data sets. The test site is located in the Red River Basin and is characterized by rich farmland where a variety of crops are grown, including wheat, barley, canola, corn, sunflowers and sugar beets. This SIR-C/X-SAR research site is applying radar remote sensing to study the characteristics of vegetation and soil moisture. The seasonal comparison between the April and October 1994 data show the dramatic differences between surface conditions on the two dates. At the time of the April acquisition, almost all agricultural fields were bare and soil moisture levels were high. In October, however, soils were drier and while most crops had been harvested, some standing vegetation was still present. The areas which are cyan in color are dark in April and bright in October. These represent fields of standing biomass (amount of vegetation in a specified area) and the differences in brightness within these cyan fields represent differences in vegetation type. The very bright fields in October represent standing broadleaf crops such as corn, which had not yet been harvested. Other standing vegetation which has less biomass, such as hay and grain fields, are less bright. The magenta indicates bare soil surfaces which were wetter (brighter) in April than in October. The variations in brightness of

  16. Space Radar Image of Oberpfaffenhofen, Germany

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a false-color, three-frequency image of the Oberpfaffenhofen supersite, southwest of Munich in southern Germany, which shows the differences in what the three radar bands can see on the ground. The image covers a 27- by 36-kilometer (17- by 22-mile) area. The center of the site is 48.09 degrees north and 11.29 degrees east. The image was acquired by the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard space shuttle Endeavour on April 13, 1994, just after a heavy storm which covered the all area with 20 centimeters (8 inches) of snow. The dark area in the center of the image is Lake Ammersee. The two smaller lakes above the Ammersee are the Worthsee and the Pilsensee. On the right of the image is the tip of the Starnbergersee. The outskirt of the city of Munich can be seen at the top of the image. The Oberpfaffenhofen supersite is the major test site for X-SAR calibration and scientific experiments such as ecology, hydrology and geology. This color composite image is a three-frequency overlay. L-band total power was assigned red, the C-band total power is shown in green and the X-band VV polarization appears blue. The colors on the image stress the differences between the L-band, C-band and X-band images. If the three frequencies were seeing the same thing, the image will appear in black and white. For example, the blue areas corresponds to area for which the X-band backscatter is relatively higher than the backscatter at L-and C-band; this behavior is characteristic of clear cuts or shorter vegetation. Similarly, the forested areas have a reddish tint. Finally, the green areas seen at the southern tip of both the Ammersee and the Pilsensee lakes indicate a marshy area. Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR

  17. Three-dimensional radar imaging techniques and systems for near-field applications

    NASA Astrophysics Data System (ADS)

    Sheen, David M.; Hall, Thomas E.; McMakin, Douglas L.; Jones, A. Mark; Tedeschi, Jonathan R.

    2016-05-01

    The Pacific Northwest National Laboratory has developed three-dimensional holographic (synthetic aperture) radar imaging techniques and systems for a wide variety of near-field applications. These applications include radar crosssection (RCS) imaging, personnel screening, standoff concealed weapon detection, concealed threat detection, throughbarrier imaging, ground penetrating radar (GPR), and non-destructive evaluation (NDE). Sequentially-switched linear arrays are used for many of these systems to enable high-speed data acquisition and 3-D imaging. In this paper, the techniques and systems will be described along with imaging results that demonstrate the utility of near-field 3-D radar imaging for these compelling applications.

  18. Optimization of synthetic aperture image quality

    NASA Astrophysics Data System (ADS)

    Moshavegh, Ramin; Jensen, Jonas; Villagomez-Hoyos, Carlos A.; Stuart, Matthias B.; Hemmsen, Martin Christian; Jensen, Jørgen Arendt

    2016-04-01

    Synthetic Aperture (SA) imaging produces high-quality images and velocity estimates of both slow and fast flow at high frame rates. However, grating lobe artifacts can appear both in transmission and reception. These affect the image quality and the frame rate. Therefore optimization of parameters effecting the image quality of SA is of great importance, and this paper proposes an advanced procedure for optimizing the parameters essential for acquiring an optimal image quality, while generating high resolution SA images. Optimization of the image quality is mainly performed based on measures such as F-number, number of emissions and the aperture size. They are considered to be the most contributing acquisition factors in the quality of the high resolution images in SA. Therefore, the performance of image quality is quantified in terms of full-width at half maximum (FWHM) and the cystic resolution (CTR). The results of the study showed that SA imaging with only 32 emissions and maximum sweep angle of 22 degrees yields a very good image quality compared with using 256 emissions and the full aperture size. Therefore the number of emissions and the maximum sweep angle in the SA can be optimized to reach a reasonably good performance, and to increase the frame rate by lowering the required number of emissions. All the measurements are performed using the experimental SARUS scanner connected to a λ/2-pitch transducer. A wire phantom and a tissue mimicking phantom containing anechoic cysts are scanned using the optimized parameters for the transducer. Measurements coincide with simulations.

  19. A Germanium-Based, Coded Aperture Imager

    SciTech Connect

    Ziock, K P; Madden, N; Hull, E; William, C; Lavietes, T; Cork, C

    2001-10-31

    We describe a coded-aperture based, gamma-ray imager that uses a unique hybrid germanium detector system. A planar, germanium strip detector, eleven millimeters thick is followed by a coaxial detector. The 19 x 19 strip detector (2 mm pitch) is used to determine the location and energy of low energy events. The location of high energy events are determined from the location of the Compton scatter in the planar detector and the energy is determined from the sum of the coaxial and planar energies. With this geometry, we obtain useful quantum efficiency in a position-sensitive mode out to 500 keV. The detector is used with a 19 x 17 URA coded aperture to obtain spectrally resolved images in the gamma-ray band. We discuss the performance of the planar detector, the hybrid system and present images taken of laboratory sources.

  20. Space Radar Image of Colorado River

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This space radar image illustrates the recent rapid urban development occurring along the lower Colorado River at the Nevada/Arizona state line. Lake Mojave is the dark feature that occupies the river valley in the upper half of the image. The lake is actually a reservoir created behind Davis Dam, the bright white line spanning the river near the center of the image. The dam, completed in 1953, is used both for generating electric power and regulating the river's flow downstream. Straddling the river south of Davis Dam, shown in white and bright green, are the cities of Laughlin, Nevada (west of the river) and Bullhead City, Arizona (east of the river). The runway of the Laughlin, Bullhead City Airport is visible as a dark strip just east of Bullhead City. The area has experienced rapid growth associated with the gambling industry in Laughlin and on the Fort Mojave Indian Reservation to the south. The community of Riviera is the bright green area in a large bend of the river in the lower left part of the image. Complex drainage patterns and canyons are the dark lines seen throughout the image. Radar is a useful tool for studying these patterns because of the instrument's sensitivity to roughness, vegetation and subtle topographic differences. This image is 50 kilometers by 35 kilometers (31 miles by 22 miles) and is centered at 35.25 degrees north latitude, 114.67 degrees west longitude. North is toward the upper right. The colors are assigned to different radar frequencies and polarizations as follows: red is L-band, horizontally transmitted and received; green is L-band, horizontally transmitted and vertically received; and blue is C-band, horizontally transmitted and vertically received. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) on April 13, 1994, onboard the space shuttle Endeavour. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Office of

  1. Mercury Radar Imaging At Arecibo

    NASA Astrophysics Data System (ADS)

    Harmon, J.

    The Arecibo telescope upgrade has enabled us to obtain radar images of Mercury of unprecedented quality. Here I report on results from Arecibo observations made dur- ing the period 1998-2001. The imaging was done using the delay-Doppler method in both its standard and long-code versions. The north polar "ice" features have been imaged at 1-km resolution. While these images strongly indicate radar backscatter- ing from volatile deposits in permanently shaded cold traps, the discovery of features in small craters and at relatively low (71-75) latitudes is difficult to reconcile with recent thermal modeling work. This suggests that our current understanding of the maintenance of water ice in the Mercurian environment is incomplete. Other (non- polar) regions have also been imaged, with the best results having come from long- code observations in the summer of 2001. These images are now indicating that all of the major radar features in the Mariner-unimaged hemisphere (including those earlier dubbed "A", "B", and "C") are associated with impact structures. Feature "A" shows a remarkable ejecta blanket and ray system as well as numerous secondary craters, all emanating from a central 85-km-diameter impact crater. Feature "B", earlier suggested as a possible volcano, now appears to be associated with an impact crater the same size as "A". Feature "C", though somewhat obscured by the Doppler equator, shows what appears to be a dense cluster of fresh craters, possibly an impactor swarm or secon- daries from a single (as yet unidentified) impact. A very large rayed impact feature has also been discovered to the south of "C". We have also obtained high-quality images over portions of the Mariner-imaged hemisphere. Here we find a strong correspon- dence between radar-bright craters and bright (and/or rayed) craters in the Mariner images. On the other hand, much of Caloris basin and its surrounding smooth plains appears radar-dark in depolarized radar images, suggesting

  2. Coded-aperture imaging in nuclear medicine

    NASA Astrophysics Data System (ADS)

    Smith, Warren E.; Barrett, Harrison H.; Aarsvold, John N.

    1989-11-01

    Coded-aperture imaging is a technique for imaging sources that emit high-energy radiation. This type of imaging involves shadow casting and not reflection or refraction. High-energy sources exist in x ray and gamma-ray astronomy, nuclear reactor fuel-rod imaging, and nuclear medicine. Of these three areas nuclear medicine is perhaps the most challenging because of the limited amount of radiation available and because a three-dimensional source distribution is to be determined. In nuclear medicine a radioactive pharmaceutical is administered to a patient. The pharmaceutical is designed to be taken up by a particular organ of interest, and its distribution provides clinical information about the function of the organ, or the presence of lesions within the organ. This distribution is determined from spatial measurements of the radiation emitted by the radiopharmaceutical. The principles of imaging radiopharmaceutical distributions with coded apertures are reviewed. Included is a discussion of linear shift-variant projection operators and the associated inverse problem. A system developed at the University of Arizona in Tucson consisting of small modular gamma-ray cameras fitted with coded apertures is described.

  3. Coded-aperture imaging in nuclear medicine

    NASA Technical Reports Server (NTRS)

    Smith, Warren E.; Barrett, Harrison H.; Aarsvold, John N.

    1989-01-01

    Coded-aperture imaging is a technique for imaging sources that emit high-energy radiation. This type of imaging involves shadow casting and not reflection or refraction. High-energy sources exist in x ray and gamma-ray astronomy, nuclear reactor fuel-rod imaging, and nuclear medicine. Of these three areas nuclear medicine is perhaps the most challenging because of the limited amount of radiation available and because a three-dimensional source distribution is to be determined. In nuclear medicine a radioactive pharmaceutical is administered to a patient. The pharmaceutical is designed to be taken up by a particular organ of interest, and its distribution provides clinical information about the function of the organ, or the presence of lesions within the organ. This distribution is determined from spatial measurements of the radiation emitted by the radiopharmaceutical. The principles of imaging radiopharmaceutical distributions with coded apertures are reviewed. Included is a discussion of linear shift-variant projection operators and the associated inverse problem. A system developed at the University of Arizona in Tucson consisting of small modular gamma-ray cameras fitted with coded apertures is described.

  4. Analysis Of Atmoshperic Effects On X-Band Synthetic Aperture Radar Observations And Precipitations Estimation

    NASA Astrophysics Data System (ADS)

    Mori, S.; Pulvirenti, L.; Marzano, F. S.; Pierdicca, N.

    2013-12-01

    This paper proposes a new methodology for the detection and quantitative estimation of intense atmospheric precipitations on images acquired by Synthetic Aperture Radars (SARs) operating at X-Band wavelengths. The proposed methodology consists of two successive steps. The first one allows detecting and distinguishing areas subjected to intense precipitation events, permanent water surfaces, flood areas and snow coverage. The second step derives an estimation of the precipitation rate using the event attenuation estimated at the previous step. This methodology is applied on two COSMO-SkyMed (CSK) satellite case studies. The first one is relative to a severe precipitation weather event, occurred in northwestern Italy (close to Liguria region) on November 3-8, 2011. The second one is relative to Hurricane “Irene” event, occurred in Eastern United States (close to Delaware) on late August 2011. In both cases X-SAR echoes and estimated rain rate is compared with corresponding products derived by available ground Weather Radars (WRs). The correlation of the precipitating cloud fields between CSK X-SAR and WR images is significant in all case studies.

  5. Space radar image of Mississippi River

    NASA Technical Reports Server (NTRS)

    1995-01-01

    This image of the Mississippi River in Mississippi, Arkansas, and Louisiana shows regions of the southern United States that are prone to flooding. Data acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture imaging radar system, which flew on two space shuttle missions in April and October 1994, can help scientists assess flooding potentials and improve land management for future agricultural development. This image was acquired on October 9, 1994, during orbit 151 of the space shuttle Endeavour. The image is centered at about 32.75 degrees north latitude and 90.5 degrees west longitude and covers an area of about 23 kilometers by 40 kilometers (14.2 miles by 24.8 miles). North is toward the upper right of the image. The different colors represent the data return in different radar channels: red is L-band, vertically transmitted and received; green is L-band vertically transmitted and horizontally received; and blue is C-band vertically transmitted and received. This site along the Mississippi River lies north of Vicksburg along the Arkansas-Louisiana-Mississippi state borders. The river marks the stateline. Louisiana and Arkansas lie above the river and Mississippi is below the river. This region is characterized by rich farmland where a variety of crops are grown. The town located in the extreme upper left hand corner is Eudora, Arkansas. The long, narrow lakes which lie roughly parallel to the river are called oxbow lakes, named for the U-shaped harness worn by an ox. Oxbows are formed when a river changes course, abandoning old channels in favor of a new course. As the river changes course, the surrounding land dries out, leaving these lakes isolated. Oxbow lakes are common in areas where rivers flow through generally flat terrain, allowing the river to easily change course. The green regions bordering the river are undeveloped forested areas

  6. Space Radar Image of Kliuchevskoi Volcano, Russia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is an image of the Kliuchevskoi volcano, Kamchatka, Russia, which began to erupt on September 30, 1994. Kliuchevskoi is the bright white peak surrounded by red slopes in the lower left portion of the image. The image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar aboard the space shuttle Endeavour on its 25th orbit on October 1, 1994. The image shows an area approximately 30 kilometers by 60 kilometers (18.5 miles by 37 miles) that is centered at 56.18 degrees north latitude and 160.78 degrees east longitude. North is toward the top of the image. The Kamchatka volcanoes are among the most active volcanoes in the world. The volcanic zone sits above a tectonic plate boundary, where the Pacific plate is sinking beneath the northeast edge of the Eurasian plate. The Endeavour crew obtained dramatic video and photographic images of this region during the eruption, which will assist scientists in analyzing the dynamics of the current activity. The colors in this image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted and vertically received); blue represents the C-band (horizontally transmitted and vertically received). The Kamchatka River runs from left to right across the image. An older, dormant volcanic region appears in green on the north side of the river. The current eruption included massive ejections of gas, vapor and ash, which reached altitudes of 20,000 meters (65,000 feet). New lava flows are visible on the flanks of Kliuchevskoi, appearing yellow/green in the image, superimposed on the red surfaces in the lower center. Melting snow triggered mudflows on the north flank of the volcano, which may threaten agricultural zones and other settlements in the valley to the north. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars

  7. Space Radar Image of Missouri River - TOPSAR

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a combined radar and topography image of an area along the Missouri River that experienced severe flooding and levee failure in the summer of 1993. The meandering course of the Missouri River is seen as the dark curving band on the left side of the image. The predominantly blue area on the left half of the image is the river's floodplain, which was completely inundated during the flood of 1993. The colors in the image represent elevations, with the low areas shown in purple, intermediate areas in blue, green and yellow, and the highest areas shown in orange. The total elevation range is 85 meters (279 feet). The higher yellow and orange area on the right side of the image shows the topography and drainage patterns typical of this part of the midwestern United States. Dark streaks and bands in the floodplain are agricultural areas that were severely damaged by levee failures during the flooding. The region enclosed by the C-shaped bend in the river in the upper part of the image is Lisbon Bottoms. A powerful outburst of water from a failed levee on the north side of Lisbon Bottoms scoured a deep channel across the fields, which shows up as purple band. As the flood waters receded, deposits of sand and silt were left behind, which now appear as dark, smooth streaks in the image. The yellow areas within the blue, near the river, are clumps of trees sitting on slightly higher ground within the floodplain. The radar 'sees' the treetops, and that is why they are so much higher (yellow) than the fields. The image was acquired by the NASA/JPL Topographic Synthetic Aperture Radar system (TOPSAR) that flew over the area aboard a DC-8 aircraft in August 1994. The elevations are obtained by a technique known as radar interferometry, in which the radar signals are transmitted by one antenna, and echoes are received by two antennas aboard the aircraft. The two sets of received signals are combined using computer processing to produce a topographic map. Similar techniques

  8. Remote sensing satellite formation for bistatic synthetic aperture radar observation

    NASA Astrophysics Data System (ADS)

    D'Errico, Marco; Moccia, Antonio

    2001-12-01

    In recent years the Italian Space Agency has been proceeding to the definition and launch of small missions. In this ambit, the BISSAT mission was proposed and selected along with five other missions for a competitive Phase A study. BISSAT mission concept consists in flying a passive SAR on board a small satellite, which observes the area illuminated by an active SAR, operating on an already existing large platform. Several scientific applications of bistatic measurements can be envisaged: improvement of image classification and pattern recognition, derivation of medium-resolution digital elevation models, velocity measurements, measurements of sea-wave spectra. BISSAT payload is developed on the basis of the X-band SAR of the COSMO/SkyMed mission, while BISSAT bus is based on an upgrade of MITA. Orbit design has been performed, leading to the same orbit parameters apart from the ascending node right ascension (5.24 degree(s) shift) and the time of the passage on the ascending node (1.17s shift). A minimum distance at the passage of the orbit crossing point of about 42 km (5.7s) is computed. To maintain adequate swath overlap along the orbit, attitude maneuver or antenna electronic steering must be envisaged and traded-off taking into account radar performance and cost of hardware upgrade.

  9. Method and apparatus for contour mapping using synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Goldstein, R. M.; Caro, E. R.; Wu, C. (Inventor)

    1985-01-01

    By using two SAR antennas spaced a known distance, B, and oriented at substantially the same look angle to illuminate the same target area, pixel data from the two antennas may be compared in phase to determine a difference delta phi from which a slant angle theta is determined for each pixel point from an equation Delta phi = (2 pi B/lambda)sin(theta - alpha), where lambda is the radar wavelength and alpha is the roll angle of the aircraft. The height, h, of each pixel point from the aircraft is determined from the equation h = R cos theta, and from the known altitude, a, of the aircraft above sea level, the altitude (elevation), a', of each point is determined from the difference a - h. This elevation data may be displayed with the SAR image by, for example, quantizing the elevation at increments of 100 feet starting at sea level, and color coding pixels of the same quantized elevation. The distance, d, of each pixel from the ground track of the aircraft used for the display may be determined more accurately from the equation d = R sin theta.

  10. Fast-neutron, coded-aperture imager

    NASA Astrophysics Data System (ADS)

    Woolf, Richard S.; Phlips, Bernard F.; Hutcheson, Anthony L.; Wulf, Eric A.

    2015-06-01

    This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

  11. Space Radar Image of Weddell Sea Ice

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is the first calibrated, multi-frequency, multi-polarization spaceborne radar image of the seasonal sea-ice cover in the Weddell Sea, Antarctica. The multi-channel data provide scientists with details about the ice pack they cannot see any other way and indicates that the large expanse of sea-ice is, in fact, comprised of many smaller rounded ice floes, shown in blue-gray. These data are particularly useful in helping scientists estimate the thickness of the ice cover which is often extremely difficult to measure with other remote sensing systems. The extent, and especially thickness, of the polar ocean's sea-ice cover together have important implications for global climate by regulating the loss of heat from the ocean to the cold polar atmosphere. The image was acquired on October 3, 1994, by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard the space shuttle Endeavour. This image is produced by overlaying three channels of radar data in the following colors: red (C-band, HH-polarization), green (L-band HV-polarization), and blue (L-band, HH-polarization). The image is oriented almost east-west with a center location of 58.2 degrees South and 21.6 degrees East. Image dimensions are 45 kilometers by 18 kilometers (28 miles by 11 miles). Most of the ice cover is composed of rounded, undeformed blue-gray floes, about 0.7 meters (2 feet) thick, which are surrounded by a jumble of red-tinged deformed ice pieces which are up to 2 meters (7 feet) thick. The winter cycle of ice growth and deformation often causes this ice cover to split apart, exposing open water or 'leads'. Ice growth within these openings is rapid due to the cold, brisk Antarctic atmosphere. Different stages of new-ice growth can be seen within the linear leads, resulting from continuous opening and closing. The blue lines within the leads are open water areas in new fractures which are roughened by wind. The bright red lines are an intermediate stage of new

  12. Feasibility of Swept Synthetic Aperture Ultrasound Imaging.

    PubMed

    Bottenus, Nick; Long, Will; Zhang, Haichong K; Jakovljevic, Marko; Bradway, David P; Boctor, Emad M; Trahey, Gregg E

    2016-07-01

    Ultrasound image quality is often inherently limited by the physical dimensions of the imaging transducer. We hypothesize that, by collecting synthetic aperture data sets over a range of aperture positions while precisely tracking the position and orientation of the transducer, we can synthesize large effective apertures to produce images with improved resolution and target detectability. We analyze the two largest limiting factors for coherent signal summation: aberration and mechanical uncertainty. Using an excised canine abdominal wall as a model phase screen, we experimentally observed an effective arrival time error ranging from 18.3 ns to 58 ns (root-mean-square error) across the swept positions. Through this clutter-generating tissue, we observed a 72.9% improvement in resolution with only a 3.75 dB increase in side lobe amplitude compared to the control case. We present a simulation model to study the effect of calibration and mechanical jitter errors on the synthesized point spread function. The relative effects of these errors in each imaging dimension are explored, showing the importance of orientation relative to the point spread function. We present a prototype device for performing swept synthetic aperture imaging using a conventional 1-D array transducer and ultrasound research scanner. Point target reconstruction error for a 44.2 degree sweep shows a reconstruction precision of 82.8 μm and 17.8 μm in the lateral and axial dimensions respectively, within the acceptable performance bounds of the simulation model. Improvements in resolution, contrast and contrast-to-noise ratio are demonstrated in vivo and in a fetal phantom. PMID:26863653

  13. Space Radar Image of Central Plain, Oman

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Bright, arc-shaped limestone hills and complex, branching drainage patterns dominate this three-frequency space radar image of a desert area in the north central plain of Oman. The hill along the left side of the image, called Jabal Fuhud, lies just south of the town of Fuhud, which appears as small bright rectangular features. The thin red lines that can be seen radiating out from this town are roads. The 'u'-shaped hill in the right center of the image is called Jabal Natih. Layers in the limestone appear as stripes which parallel the crest of the hill. This region is an active area of petroleum production because these geological structures form natural traps for oil and gas. The branching patterns on the image are ancient drainage channels that formed when the climate in this area was much wetter. Two large dry river channels, called wadis, appear on the image. Wadi Umayri is the yellow stripe at the lower right corner of the image. A second orange-colored wadi runs from right to left below the two sets of hills. The bright yellow patterns between the wadis are areas of bedrock covered with a thin layer of sand. These rocks would not be visible in conventional satellite images or photographs. This image is centered at 22.25 degrees north latitude, 56.58 degrees east longitude. The area shown is approximately 42 kilometers by 78 kilometers (26 miles by 48 miles). North is toward the upper right. The colors are assigned to different radar frequencies and polarizations as follows: red is L-band, horizontally transmitted and received; green is C-band, horizontally transmitted and vertically received; and blue is X-band, vertically transmitted and received. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) on April 10, 1994, on board the space shuttle Endeavour. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Mission to Planet Earth program.

  14. NASA/JPL's Imaging Radar Outreach Program

    NASA Technical Reports Server (NTRS)

    Freeman, A.; O'Leary, E.; Chapman, B.; Trimble, J.

    1996-01-01

    In order to build a user community for future NASA imaging radar products and programs, outreach activities have been implemented by JPL. These include: education outreach, public awareness outreach, and outreach to areas of the scientific and applications community who are not traditional imaging radar users. A key component is the NASA/JPL Imaging Radar Home Page on the World Wide Web.

  15. Integrating Radar Image Data with Google Maps

    NASA Technical Reports Server (NTRS)

    Chapman, Bruce D.; Gibas, Sarah

    2010-01-01

    A public Web site has been developed as a method for displaying the multitude of radar imagery collected by NASA s Airborne Synthetic Aperture Radar (AIRSAR) instrument during its 16-year mission. Utilizing NASA s internal AIRSAR site, the new Web site features more sophisticated visualization tools that enable the general public to have access to these images. The site was originally maintained at NASA on six computers: one that held the Oracle database, two that took care of the software for the interactive map, and three that were for the Web site itself. Several tasks were involved in moving this complicated setup to just one computer. First, the AIRSAR database was migrated from Oracle to MySQL. Then the back-end of the AIRSAR Web site was updated in order to access the MySQL database. To do this, a few of the scripts needed to be modified; specifically three Perl scripts that query that database. The database connections were then updated from Oracle to MySQL, numerous syntax errors were corrected, and a query was implemented that replaced one of the stored Oracle procedures. Lastly, the interactive map was designed, implemented, and tested so that users could easily browse and access the radar imagery through the Google Maps interface.

  16. Space Radar Image of Karisoke & Virunga Volcanoes

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a false-color composite of Central Africa, showing the Virunga volcano chain along the borders of Rwanda, Zaire and Uganda. This area is home to the endangered mountain gorillas. The image was acquired on October 3, 1994, on orbit 58 of the space shuttle Endeavour by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR). In this image red is the L-band (horizontally transmitted, vertically received) polarization; green is the C-band (horizontally transmitted and received) polarization; and blue is the C-band (horizontally transmitted and received) polarization. The area is centered at about 2.4 degrees south latitude and 30.8 degrees east longitude. The image covers an area 56 kilometers by 70 kilometers (35 miles by 43 miles). The dark area at the top of the image is Lake Kivu, which forms the border between Zaire (to the right) and Rwanda (to the left). In the center of the image is the steep cone of Nyiragongo volcano, rising 3,465 meters (11,369 feet) high, with its central crater now occupied by a lava lake. To the left are three volcanoes, Mount Karisimbi, rising 4,500 meters (14,800 feet) high; Mount Sabinyo, rising 3,600 meters (12,000 feet) high; and Mount Muhavura, rising 4,100 meters (13,500 feet) high. To their right is Nyamuragira volcano, which is 3,053 meters (10,017 feet) tall, with radiating lava flows dating from the 1950s to the late 1980s. These active volcanoes constitute a hazard to the towns of Goma, Zaire and the nearby Rwandan refugee camps, located on the shore of Lake Kivu at the top left. This radar image highlights subtle differences in the vegetation of the region. The green patch to the center left of the image in the foothills of Karisimbi is a bamboo forest where the mountain gorillas live. The vegetation types in this area are an important factor in the habitat of mountain gorillas. Researchers at Rutgers University in New Jersey and the Dian Fossey Gorilla Fund in London will use this data to produce

  17. Joint azimuth and elevation localization estimates in 3D synthetic aperture radar scenarios

    NASA Astrophysics Data System (ADS)

    Pepin, Matthew

    2015-05-01

    The location of point scatterers in Synthetic Aperture Radar (SAR) data is exploited in several modern analyzes including persistent scatter tracking, terrain deformation, and object identification. The changes in scatterers over time (pulse-to-pulse including vibration and movement, or pass-to-pass including direct follow on, time of day, and season), can be used to draw more information about the data collection. Multiple pass and multiple antenna SAR scenarios have extended these analyzes to location in three dimensions. Either multiple passes at different elevation angles may be .own or an antenna array with an elevation baseline performs a single pass. Parametric spectral estimation in each dimension allows sub-pixel localization of point scatterers in some cases additionally exploiting the multiple samples in each cross dimension. The accuracy of parametric estimation is increased when several azimuth passes or elevations (snapshots) are summed to mitigate measurement noise. Inherent range curvature across the aperture however limits the accuracy in the range dimension to that attained from a single pulse. Unlike the stationary case where radar returns may be averaged the movement necessary to create the synthetic aperture is only approximately (to pixel level accuracy) removed to form SAR images. In parametric estimation increased accuracy is attained when two dimensions are used to jointly estimate locations. This paper involves jointly estimating azimuth and elevation to attain increased accuracy 3D location estimates. In this way the full 2D array of azimuth and elevation samples is used to obtain the maximum possible accuracy. In addition the independent dimension collection geometry requires choosing which dimension azimuth or elevation attains the highest accuracy while joint estimation increases accuracy in both dimensions. When maximum parametric estimation accuracy in azimuth is selected the standard interferometric SAR scenario results. When

  18. Space Radar Image of Oetzal, Austria

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This image is a false-color composite of Oetzal, Austria located in the Central Alps centered at 46.8 degrees north latitude, 10.70 degrees east longitude, at the border between Switzerland (top), Italy (left) and Austria (right and bottom). The area shown is 50 kilometers (30 miles) south of Innsbruck, Austria. This image was acquired by the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on its 14th orbit. Oetztal is a SIR-C/X-SAR hydrology supersite. Approximately one quarter of this image is covered by glaciers, the largest of which, Gepatschferner, is visible as a triangular yellow patch in the center of the scene. The summits of the main peaks reach elevations between 3,500 and 3,768 meters (11,500 and 12,362 feet) above sea level. The tongues of the glaciers are descending from elevated plateaus down into narrow valleys which were formed during the last ice age. This color image was produced in C-band using multi-polarization information (red=CHV, green=CVV,blue=CVV/CHV). The blue areas are lakes (Gepatsch dam at center right; Lake Muta at top right) and glacier ice. The yellow areas are slopes facing the radar and areas of dry snow. Purple corresponds to slopes facing away from the radar. Yellow in the valley bottom corresponds to tree covered areas. There is 30 to 50 centimeters (12 to 20 inches) of dry, fresh snow on the glaciers, and about 10 centimeters (4 inches) in the valley at the city of Vent, Austria (center). At these data were taken, the weather was cold, with snow and thick fog. The entire area would appear white to an optical sensor because it is all covered under a winter snowpack. Researchers are interested in Oetztal because knowing how glaciers shrink and grow over time is an important indication of climatic change. Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth (MTPE). The radars illuminate Earth with

  19. Fast parametric beamformer for synthetic aperture imaging.

    PubMed

    Nikolov, Svetoslav Ivanov; Jensen, Jørgen Arendt; Tomov, Borislav Gueorguiev

    2008-08-01

    This paper describes the design and implementation of a real-time delay-and-sum synthetic aperture beamformer. The beamforming delays and apodization coefficients are described parametrically. The image is viewed as a set of independent lines that are defined in 3D by their origin, direction, and inter-sample distance. The delay calculation is recursive and inspired by the coordinate rotation digital computer (CORDIC) algorithm. Only 3 parameters per channel and line are needed for their generation. The calculation of apodization coefficients is based on a piece- wise linear approximation. The implementation of the beamformer is optimized with respect to the architecture of a novel synthetic aperture real-time ultrasound scanner (SARUS), in which 4 channels are processed by the same set of field-programmable gate arrays (FPGA). In synthetic transmit aperture imaging, low-resolution images are formed after every emission. Summing all low-resolution images produces a perfectly focused high-resolution image. The design of the beamformer is modular, and a single beamformation unit can produce 4600 low-resolution images per second, each consisting of 32 lines and 1024 complex samples per line. In its present incarnation, 3 such modules fit in a single device. The summation of low-resolution images is performed internally in the FPGA to reduce the required bandwidth. The delays are calculated with a precision of 1/16th of a sample, and the apodization coefficients with 7-bit precision. The accumulation of low-resolution images is performed with 24-bit precision. The level of the side- and grating lobes, introduced by the use of integer numbers in the calculations and truncation of intermediate results, is below -86 dB from the peak. PMID:18986919

  20. Ultrawideband imaging radar based on OFDM: system simulation analysis

    NASA Astrophysics Data System (ADS)

    Garmatyuk, Dmitriy

    2006-05-01

    Orthogonal frequency division-multiplexing (OFDM) is rapidly emerging as a preferred method of UWB signaling in commercial applications aimed mainly at low-power, high data-rate communications. This paper explores the possibility of applying OFDM to use in imaging radar technology. Ultra-wideband nature of the signal provides for high resolution of the radar, whereas usage of multi-sub-carrier method of modulation allows for dynamic spectrum allocation. Robust multi-path performance of OFDM signals and heavy reliance of transceiver design on digital processors easily implemented in modern VLSI technology make a number of possible applications viable, e.g.: portable high-resolution indoor radar/movement monitoring system; through-the-wall/foliage synthetic aperture imaging radar with a capability of image transmission/broadcasting, etc. Our work is aimed to provide a proof-of-concept simulation scenario to explore numerous aspects of UWB-OFDM radar imaging through evaluating range and cross-range imaging performance of such a system with an eventual goal of software-defined radio (SDR) implementation. Stripmap SAR topology was chosen for modeling purposes. Range/cross-range profiles were obtained along with full 2-D images for multi-target in noise scenarios. Model set-up and results of UWB-OFDM radar imaging simulation study using Matlab/Simulink modeling are presented and discussed in this paper.

  1. Extending interferometric synthetic aperture radar measurements from one to two dimensions

    NASA Astrophysics Data System (ADS)

    Bechor, Noah

    Interferometric synthetic aperture radar (InSAR), a very effective technique for measuring crustal deformation, provides measurements in only one dimension, along the radar line of sight. Imaging radar measurements from satellite-based systems are sensitive to both vertical and across-track displacements, but insensitive to along-track displacement. Multiple observations can resolve the first two components, but the along-track component remains elusive. The best existing method to obtain the along-track displacement involves pixel-level azimuth cross-correlation. The measurements are quite coarse (typically 15 cm precision), and they require large computation times. In contrast, across-track and vertical InSAR measurements can reach centimeter-level precision and are readily derived. We present a new method to extract along-track displacements from InSAR data. The new method, multiple aperture InSAR (MAI), is based on split-beam processing of InSAR data to create forward- and backward-looking interferograms. The phase difference between the two modified interferograms provides the along-track displacement component. Thus, from each conventional InSAR pair we extract two components of the displacement vector: one along the line of sight, the other in the along-track direction. Multiple MAI observations, either at two look angles or from the ascending and descending radar passes, then yield the three-dimensional displacement field. We analyze precision of our method by comparing our solution to GPS and offset-derived along-track displacements from interferograms of the M7.1 1999, Hector Mine earthquake. The RMS error between GPS displacements and our results ranges from 5 to 8.8cm. Our method is consistent with along-track displacements derived by pixel-offsets, themselves limited to 12-15cm precision. The theoretical MAI precision depends on SNR and coherence. For SNR=100 the expected precision is 3, 11cm for coherence of 0.8, 0.4, respectively. Finally, we

  2. Complementary lattice arrays for coded aperture imaging

    NASA Astrophysics Data System (ADS)

    Ding, Jie; Noshad, Mohammad; Tarokh, Vahid

    2016-05-01

    In this work, we consider complementary lattice arrays in order to enable a broader range of designs for coded aperture imaging systems. We provide a general framework and methods that generate richer and more flexible designs than existing ones. Besides this, we review and interpret the state-of-the-art uniformly redundant arrays (URA) designs, broaden the related concepts, and further propose some new design methods.

  3. Synthetic Aperture Radar (sar) Based Classifiers for Land Applications in Germany

    NASA Astrophysics Data System (ADS)

    Suresh, G.; Gehrke, R.; Wiatr, T.; Hovenbitzer, M.

    2016-06-01

    Land cover information is essential for urban planning and for land cover change monitoring. This paper presents an overview of the work conducted at the Federal Agency for Cartography and Geodesy (BKG) with respect to Synthetic Aperture Radar (SAR) based land cover classification. Two land cover classification approaches using SAR images are reported in this paper. The first method involves a rule-based classification using only SAR backscatter intensity while the other method involves supervised classification of a polarimetric composite of the same SAR image. The LBM-DE has been used for training and validation of the SAR classification results. Images acquired from the Sentinel-1a satellite are used for classification and the results have been reported and discussed. The availability of Sentinel-1a images that are weather and daylight independent allows for the creation of a land cover classification system that can be updated and validated periodically, and hence, be used to assist other land cover classification systems that use optical data. With the availability of Sentinel-2 data, land cover classification combining Sentinel-1a and Sentinel-2 images present a path for the future.

  4. Synthetic aperture acoustic imaging of non-metallic cords

    NASA Astrophysics Data System (ADS)

    Glean, Aldo A. J.; Good, Chelsea E.; Vignola, Joseph F.; Judge, John A.; Ryan, Teresa J.; Bishop, Steven S.; Gugino, Peter M.; Soumekh, Mehrdad

    2012-06-01

    This work presents a set of measurements collected with a research prototype synthetic aperture acoustic (SAA) imaging system. SAA imaging is an emerging technique that can serve as an inexpensive alternative or logical complement to synthetic aperture radar (SAR). The SAA imaging system uses an acoustic transceiver (speaker and microphone) to project acoustic radiation and record backscatter from a scene. The backscattered acoustic energy is used to generate information about the location, morphology, and mechanical properties of various objects. SAA detection has a potential advantage when compared to SAR in that non-metallic objects are not readily detectable with SAR. To demonstrate basic capability of the approach with non-metallic objects, targets are placed in a simple, featureless scene. Nylon cords of five diameters, ranging from 2 to 15 mm, and a joined pair of 3 mm fiber optic cables are placed in various configurations on flat asphalt that is free of clutter. The measurements were made using a chirp with a bandwidth of 2-15 kHz. The recorded signal is reconstructed to form a two-dimensional image of the distribution of acoustic scatterers within the scene. The goal of this study was to identify basic detectability characteristics for a range of sizes and configurations of non-metallic cord. It is shown that for sufficiently small angles relative to the transceiver path, the SAA approach creates adequate backscatter for detectability.

  5. Space Radar Image of Taal Volcano, Philippines

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is an image of Taal volcano, near Manila on the island of Luzon in the Philippines. The black area in the center is Taal Lake, which nearly fills the 30-kilometer-diameter (18-mile) caldera. The caldera rim consists of deeply eroded hills and cliffs. The large island in Taal Lake, which itself contains a crater lake, is known as Volcano Island. The bright yellow patch on the southwest side of the island marks the site of an explosion crater that formed during a deadly eruption of Taal in 1965. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on its 78th orbit on October 5, 1994. The image shows an area approximately 56 kilometers by 112 kilometers (34 miles by 68 miles) that is centered at 14.0 degrees north latitude and 121.0 degrees east longitude. North is toward the upper right of the image. The colors in this image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted and vertically received); blue represents the C-band (horizontally transmitted and vertically received). Since 1572, Taal has erupted at least 34 times. Since early 1991, the volcano has been restless, with swarms of earthquakes, new steaming areas, ground fracturing, and increases in water temperature of the lake. Volcanologists and other local authorities are carefully monitoring Taal to understand if the current activity may foretell an eruption. Taal is one of 15 'Decade Volcanoes' that have been identified by the volcanology community as presenting large potential hazards to population centers. The bright area in the upper right of the image is the densely populated city of Manila, only 50 kilometers (30 miles) north of the central crater. Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth

  6. Space Radar Image of Kilauea, Hawaii

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This color composite C-band and L-band image of the Kilauea volcano on the Big Island of Hawaii was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) flying on space shuttle Endeavour. The city of Hilo can be seen at the top. The image shows the different types of lava flows around the crater Pu'u O'o. Ash deposits which erupted in 1790 from the summit of Kilauea volcano show up as dark in this image, and fine details associated with lava flows which erupted in 1919 and 1974 can be seen to the south of the summit in an area called the Ka'u Desert. In addition, the other historic lava flows created in 1881 and 1984 from Mauna Loa volcano (out of view to the left of this image) can be easily seen despite the fact that the surrounding area is covered by forest. Such information will be used to map the extent of such flows, which can pose a hazard to the subdivisions of Hilo. Highway 11 is the linear feature running from Hilo to the Kilauea volcano. The Kilauea volcano has been almost continuously active for more than the last 11 years. Field teams that were on the ground specifically to support these radar observations report that there was vigorous surface activity about 400 meters (one-quarter mile) inland from the coast. A moving lava flow about 200 meters (660 feet) in length was observed at the time of the shuttle overflight, raising the possibility that subsequent images taken during this mission will show changes in the landscape. This image is centered at 19.2 degrees north latitude and 155.2 degrees west longitude. Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific

  7. Space based topographic mapping experiment using Seasat synthetic aperture radar and LANDSAT 3 return beam vidicon imagery

    NASA Technical Reports Server (NTRS)

    Mader, G. L.

    1981-01-01

    A technique for producing topographic information is described which is based on same side/same time viewing using a dissimilar combination of radar imagery and photographic images. Common geographic areas viewed from similar space reference locations produce scene elevation displacements in opposite direction and proper use of this characteristic can yield the perspective information necessary for determination of base to height ratios. These base to height ratios can in turn be used to produce a topographic map. A test area covering the Harrisburg, Pennsylvania region was observed by synthetic aperture radar on the Seasat satellite and by return beam vidicon on by the LANDSAT - 3 satellite. The techniques developed for the scaling re-orientation and common registration of the two images are presented along with the topographic determination data. Topographic determination based exclusively on the images content is compared to the map information which is used as a performance calibration base.

  8. Developing a small multi frequency synthetic aperture radar for UAS operation: the SlimSAR

    NASA Astrophysics Data System (ADS)

    Zaugg, Evan; Edwards, Matthew; Margulis, Alex

    2010-04-01

    The SlimSAR is a small, low-cost, Synthetic Aperture Radar (SAR) and represents a new advancement in high-performance SAR. ARTEMIS employed a unique design methodology in designing the SlimSAR that exploits previous developments. The system is designed to be smaller, lighter, and more flexible while consuming less power than typical SAR systems. The system consists of an L-band core and frequency block converters and is very suitable for use on a number of small UAS's. Both linear-frequency-modulated continuous-wave (LFM-CW) and pulsed modes have been tested. The LFM-CW operation achieves high signal-to-noise ratio while transmitting with less peak power than a comparable pulsed system. The flexible control software allows us to change the radar parameters in flight. The system has a built-in high quality GPS/IMU motion measurement solution and can also be packaged with a small data link and a gimbal for high frequency antennas. Multi-frequency SAR provides day and night imaging through smoke, dust, rain, and clouds with the advantages of additional capabilities at different frequencies (i.e. dry ground and foliage penetration at low frequencies, and change detection at high frequencies.)

  9. A High Resolution, Light-Weight, Synthetic Aperture Radar for UAV Application

    SciTech Connect

    Doerry, A.W.; Hensley, W.H.; Stence, J.; Tsunoda, S.I. Pace, F.; Walker, B,C.; Woodring, M.

    1999-05-27

    (U) Sandia National Laboratories in collaboration with General Atomics (GA) has designed and built a high resolution, light-weight, Ku-band Synthetic Aperture Radar (SAR) known as "Lynx". Although Lynx can be operated on a wide variety of manned and unmanned platforms, its design is optimized for use on medium altitude Unmanned Aerial Vehicles (UAVS). In particular, it can be operated on the Predator, I-GNAT, and Prowler II platforms manufactured by GA. (U) The radar production weight is less than 120 lb and operates within a 3 GHz band from 15.2 GHz to 18.2 GHz with a peak output power of 320 W. Operating range is resolution and mode dependent but can exceed 45 km in adverse weather (4 mm/hr rain). Lynx has operator selectable resolution and is capable of 0.1 m resolution in spotlight mode and 0.3 m resolution in stripmap mode, over substantial depression angles (5 to 60 deg) and squint angles (broadside ±45 deg). Real-time Motion Compensation is implemented to allow high-quality image formation even during vehicle turns and other maneuvers.

  10. Determining the mixing of oil and sea water using polarimetric synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Minchew, Brent

    2012-08-01

    Knowledge of the characteristics of spilled oil in the ocean is important for cleanup operations, predictions of the impact on wildlife, and studies of the nature of the ocean surface and currents. Herein I discuss a method for evaluating the characteristics of oil in a marine environment using synthetic aperture radar (SAR) and present a new, simple classification, called the oil/water mixing index (Mdex), to quickly assess the results. I link the Mdex results to the Bonn Agreement for Oil Appearance Codes (BAOAC) for aerial observers and demonstrate the Mdex on Uninhabited Aerial Vehicle SAR (UAVSAR) data collected June 23, 2010 over the former site of the Deepwater Horizon (DWH) drilling rig. The Mdex map shows a more heterogeneous oil swath than do radar backscatter images and features within the oil are consistent with features present in previously published, near-coincident optical imagery. The Mdex results indicate that most of the oil near the DWH was mixed with sea water to a minimum depth of a few millimeters, though some areas containing relatively thin films are observed.

  11. SPace Radar Image of Mt. Pinatubo, Philippines

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a false color L-band and C-band image of the area around Mount Pinatubo in the Philippines, centered at about 15 degrees north latitude, 120.5 degrees east longitude. This image was acquired by the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on orbit 78 on April 13, 1994. The false-color composite is made by displaying the L-band HH return in red, the L-band HV return in green and the C-band HV return in blue. The area shown is approximately 45 by 68 kilometers (28 by 42 miles). The main volcanic crater on Mount Pinatubo produced by the June 1991 eruptions, and the steep slopes on the upper flanks of the volcano, are easily seen in this image. The red color on the high slopes show the rougher ash deposited during the 1991 eruption. The dark drainages are the smooth mudflows which continue to flood the river valleys after heavy rain. Radar images such as this one can be used to identify the areas flooded by mudflows, which are difficult to distinguish visually, and to assess the rate at which the erosion and deposition continues. A key aspect of the second SIR-C/X-SAR mission in August 1994 will be to collect a second image of Pinatubo during the summer monsoon season -- new mudflows will have occurred -- and to evaluate the short-term changes. The 1991 eruption of Mount Pinatubo in the Philippines is well known for its near-global effects on the atmosphere and climate due to the large amount of sulfur dioxide that was injected into the upper atmosphere. What is less widely known is that even today the volcano continues to be a major hazard to the people who have returned to the area around the volcano. Dangerous mudflows (called 'lahars') are often generated by heavy rains, and these can still sweep down river valleys and wash out roads and villages, or bury low lying areas in several meters of mud and volcanic debris. These mudflows will continue to be a severe hazard around Pinatubo for

  12. Space Radar Image of Colombian Volcano

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a radar image of a little known volcano in northern Colombia. The image was acquired on orbit 80 of space shuttle Endeavour on April 14, 1994, by the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR). The volcano near the center of the image is located at 5.6 degrees north latitude, 75.0 degrees west longitude, about 100 kilometers (65 miles) southeast of Medellin, Colombia. The conspicuous dark spot is a lake at the bottom of an approximately 3-kilometer-wide (1.9-mile) volcanic collapse depression or caldera. A cone-shaped peak on the bottom left (northeast rim) of the caldera appears to have been the source for a flow of material into the caldera. This is the northern-most known volcano in South America and because of its youthful appearance, should be considered dormant rather than extinct. The volcano's existence confirms a fracture zone proposed in 1985 as the northern boundary of volcanism in the Andes. The SIR-C/X-SAR image reveals another, older caldera further south in Colombia, along another proposed fracture zone. Although relatively conspicuous, these volcanoes have escaped widespread recognition because of frequent cloud cover that hinders remote sensing imaging in visible wavelengths. Four separate volcanoes in the Northern Andes nations ofColombia and Ecuador have been active during the last 10 years, killing more than 25,000 people, including scientists who were monitoring the volcanic activity. Detection and monitoring of volcanoes from space provides a safe way to investigate volcanism. The recognition of previously unknown volcanoes is important for hazard evaluations because a number of major eruptions this century have occurred at mountains that were not previously recognized as volcanoes. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of

  13. Space Radar Image of Bebedauro, Brazil, seasonal

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is an X-band image showing seasonal changes at the hydrological test site of Bebedouro in Brazil. The image is centered at 9 degrees south latitude and 40.2 degrees west longitude. This image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on April 10, 1994, during the first flight of the radar system, and on October 1, 1994, during the second mission. The swath width is approximately 16.5 kilometers (10.5 miles) wide. The image channels have the following color assignments: red represents data acquired on April 10; green represents data acquired on October 1; blue corresponds to the ratio of the two data sets. Agriculture plays an important economic and social role in Brazil. One of the major problems related to Brazilian agriculture is estimating the size of planting areas and their productivity. Due to cloud cover and the rainy season, which occurs from November through April, optical and infrared Earth observations are seldom used to survey the region. An additional goal of monitoring this region is to watch the floodplains of rivers like Rio Sao Francisco in order to determine suitable locations for additional agricultural fields. This area belongs to the semi-arid northeastern region of Brazil, where estimates have suggested that about 10 times more land could be used for agriculture, including some locations which could be used for irrigation projects. Monitoring of soil moisture during the important summer crop season is of high priority for the future development and productivity of this region. In April the area was covered with vegetation because of the moisture of the soil and only small differences could be seen in X-band data. In October the run-off channels of this hilly region stand out quite clearly because the greenish areas indicated much less soil moisture and water content in plants. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR

  14. Space Radar Image of Mammoth, California

    NASA Technical Reports Server (NTRS)

    1999-01-01

    These two images were created using data from the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR). The image on the left is a false-color composite of the Mammoth Mountain area in California's Sierra Nevada Mountains centered at 37.6 degrees north, 119.0 degrees west. It was acquired on-board the space shuttle Endeavour on its 67th orbit on April 13, 1994. In the image on the left, red is C-band HV-polarization, green is C-band HH-polarization and blue is the ratio of C-band VV-polarization to C-band HV-polarization. On the right is a classification map of the surface features which was developed by SIR-C/X-SAR science team members at the University of California, Santa Barbara. The area is about 23 by 46 kilometers (14 by 29 miles). In the classification image, the colors represent the following surfaces: White snow Red frozen lake, covered by snow Brown bare ground Blue lake (open water) Yellow short vegetation (mainly brush) Green sparse forest Dark green dense forest Maps like this one are helpful to scientists studying snow wetness and snow water equivalent in the snow pack. Across the globe, over major portions of the middle and high latitudes, and at high elevations in the tropical latitudes, snow and alpine glaciers are the largest contributors to run-off in rivers and to ground-water recharge. Snow hydrologists are using radar in an attempt to estimate both the quantity of water held by seasonal snow packs and the timing of snow melt. Snow and ice also play important roles in regional climates; understanding the processes in seasonal snow cover is also important for studies of the chemical balance of alpine drainage basins. SIR-C/X-SAR is a powerful tool because it is sensitive to most snow pack conditions and is less influenced by weather conditions than other remote sensing instruments, such as the Landsat satellite. Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth

  15. Space Radar Image of Dublin, Ireland

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This radar image of Dublin, Ireland, shows how the radar distinguishes between densely populated urban areas and nearby areas that are relatively unsettled. In the center of the image is the city's natural harbor along the Irish Sea. The pinkish areas in the center are the densely populated parts of the city and the blue/green areas are the suburbs. The two ends of the Dublin Bay are Howth Point, the circular peninsula near the upper right side of the image, and Dun Laoghaire, the point to the south. The small island just north of Howth is called 'Ireland's Eye,' and the larger island, near the upper right corner of the image is Lambay Island. The yellow/green mountains in the lower left of the image (south) are the Wicklow Mountains. The large lake in the lower left, nestled within these mountains, is the Poulaphouca Reservoir along River Liffey. The River Liffey, the River Dodden and the Tolka River are the three rivers that flow into Dublin. The straight features west of the city are the Grand Canal and the three rivers are the faint lines above and below these structures. The dark X-shaped feature just to the north of the city is the Dublin International Airport. The image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture (SIR-C/X-SAR) when it flew aboard the space shuttle Endeavour on April 11, 1994. This area is centered at 53.3 degrees north latitude, 6.2 degrees west longitude. The area shown is approximately 55 kilometers by 42 kilometers (34 miles by 26 miles). The colors are assigned to different frequencies and polarizations of the radar as follows: Red is L-band horizontally transmitted, horizontally received; green is L-band vertically transmitted, vertically received; and blue is C-band vertically transmitted, vertically received. SIR-C/X-SAR, a joint mission of the German, Italian, and the United States space agencies, is part of NASA's Mission to Planet Earth.

  16. Imaging radar polarimetry from wave synthesis

    NASA Technical Reports Server (NTRS)

    Zebker, Howard A.; Van Zyl, Jakob J.; Held, Daniel N.

    1987-01-01

    A new approach is reported to the measurement of the complete polarization signature of each resolution element in an image implemented with an airborne synthetic aperture radar system. Signals recorded on one data pass from orthogonal linearly polarized antennas are utilized. The signals are combined in a data processor to synthesize any desired combination of transmit and receive polarizations. The technique permits measurement of the complex, multichannel reflectivity of a scene on a single aircraft pass and to late reprocess the data to provide multiple image maps, with each representing the backscattered energy from the scene measured with a different combination of observational transmit and recieve polarizations. The resulting polarization signature measurements indicate optimum polarizations for observations of certain classes of objects and give insight into the identification of dominant scattering mechanisms for each kind of object. The mathematical model for polarization synthesis is summarized, and some theoretical polarization measurements are illustrated for several types of targets. The overall radar system implementation is described in detail. Some analyses of data acquired on three aircraft flights are presented. The technique has been applied to mapping and differentiation of lava flows and to differentiation of forested and clear-cut areas.

  17. An atlas of November 1978 synthetic aperture radar digitized imagery for oil spill studies

    NASA Technical Reports Server (NTRS)

    Maurer, H. E.; Oderman, W.; Crosswell, W. F.

    1982-01-01

    A data set is described which consists of digitized synthetic aperture radar (SAR) imagery plus correlative data and some preliminary analysis results. This data set should be of value to experimenters who are interested in the SAR instrument and its application to the detection and monitoring of oil on water and other distributed targets.

  18. Space Radar Image of Safsaf, North Africa

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a false-color image of the uninhabited Safsaf Oasis in southern Egypt near the Egypt/Sudan border. It was produced from data obtained from the L-band and C-band radars that are part of the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard space shuttle Endeavour on April 9, 1994. The image is centered at 22 degree north latitude, 29 degrees east longitude. It shows detailed structures of bedrock; the dark blue sinuous lines are braided channels that occupy part of an old broad river valley. On the ground and in optical photographs, this big valley and the channels in it are invisible because they are entirely covered by windblown sand. Some of these same channels were observed in SIR-A images in 1981. It is hypothesized that the large valley was carved by one of several ancient predecessor rivers that crossed this part of North Africa, flowing westward, tens of millions of years before the Nile River existed. The Nile flows north about 300 kilometers (200 miles) to the east. The small channels are younger, and probably formed during relatively wet climatic periods within the past few hundred thousand years. This image shows that the channels are in a river valley located in an area where U.S. Geological Survey geologists and archeologists discovered an unusual concentration of hand axes (stone tools) used by Early Man (Homo erectus) hundreds of thousands of years ago. The image clearly shows that in wetter times, the valley would have supported game animals and vegetation. Today, as a result of climate change, the area in uninhabited and lacks water except fora few scattered oases. This color composite image was produced from C-band and L-band horizontal polarization images. The C-band image was assigned red, the L-band (HH) polarization image is shown in green, and the ratio of these two images (LHH/CHH) appears in blue. The primary and composite colors on the image indicate the degree to which the C-band, H-band, their

  19. Space Radar Image of Safsaf, North Africa

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is a false-color image of the uninhabited Safsaf Oasis in southern Egypt near the Egypt/Sudan border. It was produced from data obtained from the L-band and C-band radars that are part of the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard space shuttle Endeavour on April 9, 1994. The image is centered at 22 degree north latitude, 29 degrees east longitude. It shows detailed structures of bedrock; the dark blue sinuous lines are braided channels that occupy part of an old broad river valley. On the ground and in optical photographs, this big valley and the channels in it are invisible because they are entirely covered by windblown sand. Some of these same channels were observed in SIR-A images in 1981. It is hypothesized that the large valley was carved by one of several ancient predecessor rivers that crossed this part of North Africa, flowing westward, tens of millions of years before the Nile River existed. The Nile flows north about 300 kilometers (200 miles) to the east. The small channels are younger, and probably formed during relatively wet climatic periods within the past few hundred thousand years. This image shows that the channels are in a river valley located in an area where U.S. Geological Survey geologists and archeologists discovered an unusual concentration of hand axes (stone tools) used by Early Man (Homo erectus) hundreds of thousands of years ago. The image clearly shows that in wetter times, the valley would have supported game animals and vegetation. Today, as a result of climate change, the area in uninhabited and lacks water except fora few scattered oases. This color composite image was produced from C-band and L-band horizontal polarization images. The C-band image was assigned red, the L-band (HH) polarization image is shown in green, and the ratio of these two images (LHH/CHH) appears in blue. The primary and composite colors on the image indicate the degree to which the C-band, H-band, their

  20. An Integrated Navigation System using GPS Carrier Phase for Real-Time Airborne Synthetic Aperture Radar (SAR)

    SciTech Connect

    Fellerhoff, J. Rick; Kim, Theodore J.; Kohler, Stewart M.

    1999-06-24

    A Synthetic Aperture Radar (SAR) requires accu- rate measurement of the motion of the imaging plat- form to produce well-focused images with minimal absolute position error. The motion measurement (MoMeas) system consists of a inertial measurement unit (IMU) and a P-code GPS receiver that outputs corrected ephemeris, L1 & L2 pseudoranges, and L1 & L2 carrier phase measurements. The unknown initial carrier phase biases to the GPS satellites are modeled as states in an extended Kalman filter and the resulting integrated navigation solution has po- sition errors that change slowly with time. Position error drifts less than 1- cm/sec have been measured from the SAR imagery for various length apertures.

  1. Analyses of radar images of small craters

    NASA Astrophysics Data System (ADS)

    Greeley, R.; Christensen, P. R.; McHone, J. F.

    1985-04-01

    Clouds hide the surface of Venus from all but radar imaging systems, supplemented by limited views from land spacecraft. Among the surfaces features likely to be observed by radar are craters that have formed by a variety of processes. In order to assess the radar characteristics of craters, volcanic craters and impact structures on Earth are described as imaged by the Shuttle Imaging Radar (SIR-A) experiment. Although most of the craters are small, this analysis provides insight into the ability to discriminate craters of various origins and provides some basis for interpreting radar images returned from Venus.

  2. Imaging radar techniques for remote sensing applications.

    NASA Technical Reports Server (NTRS)

    Zelenka, J. S.

    1972-01-01

    The basic concepts of fine-resolution, imaging radar systems are reviewed. Both side-looking and hologram (downward-looking) radars are described and compared. Several examples of microwave imagery obtained with these two types of systems are shown.

  3. Exploiting synthetic aperture radar imagery for retrieving vibration signatures of concealed machinery

    NASA Astrophysics Data System (ADS)

    Pérez, Francisco; Campbell, Justin B.; Jaramillo, Monica; Dunkel, Ralf; Atwood, Thomas; Doerry, Armin; Gerstle, Walter H.; Santhanam, Balu; Hayat, Majeed M.

    2016-05-01

    It has been demonstrated that the instantaneous acceleration associated with vibrating objects that are directly imaged by synthetic aperture radar (SAR) can be estimated through the application of the discrete fractional Fourier transform (DFrFT) using the information contained in the complex SAR image. In general, vibration signatures may include, for example, the number of chirped sinusoids as well as their respective base frequencies and chirp rates. By further processing the DFrFT-processed data for clutter-noise rejection by means of pseudo- subspace methods, has been shown that the SAR-vibrometry method can be reliable as long as the signal-to-noise ratio (SNR) and the signal-to-clutter ratio (SCR) of the slow-time SAR signal at the range-line of interest exceeds 15dB. Meanwhile, the Nyquist theorem dictates that the maximum measurable vibration frequency is limited by half of the pulse-repetition frequency. This paper focuses on the detection and estimation of vibrations generated by machinery concealed within buildings and other structures. This is a challenging task in general because the vibration signatures of the source are typically altered by their housing structure; moreover, the SNR at the surface of the housing structure tends to be reduced. Here, experimental results for three different vibrating targets, including one concealed target, are reported using complex SAR images acquired by the General Atomics Lynx radar at resolutions of 1-ft and 4-in. The concealed vibrating target is actuated by a gear motor with an off-balance weight attached to it, which is enclosed by a wooden housing. The vibrations of the motor are transmitted to a chimney that extends above the housing structure. Using the SAR vibrometry approach, it is shown that it is possible to distinguish among the three vibrating objects based upon their vibration signatures.

  4. Inverse synthetic aperture radar processing using parametric time-frequency estimators Phase I

    SciTech Connect

    Candy, J.V., LLNL

    1997-12-31

    This report summarizes the work performed for the Office of the Chief of Naval Research (ONR) during the period of 1 September 1997 through 31 December 1997. The primary objective of this research was aimed at developing an alternative time-frequency approach which is recursive-in-time to be applied to the Inverse Synthethic Aperture Radar (ISAR) imaging problem discussed subsequently. Our short term (Phase I) goals were to: 1. Develop an ISAR stepped-frequency waveform (SFWF) radar simulator based on a point scatterer vehicular target model incorporating both translational and rotational motion; 2. Develop a parametric, recursive-in-time approach to the ISAR target imaging problem; 3. Apply the standard time-frequency short-term Fourier transform (STFT) estimator, initially to a synthesized data set; and 4. Initiate the development of the recursive algorithm. We have achieved all of these goals during the Phase I of the project and plan to complete the overall development, application and comparison of the parametric approach to other time-frequency estimators (STFT, etc.) on our synthesized vehicular data sets during the next phase of funding. It should also be noted that we developed a batch minimum variance translational motion compensation (TMC) algorithm to estimate the radial components of target motion (see Section IV). This algorithm is easily extended to recursive solution and will probably become part of the overall recursive processing approach to solve the ISAR imaging problem. Our goals for the continued effort are to: 1. Develop and extend a complex, recursive-in-time, time- frequency parameter estimator based on the recursive prediction error method (RPEM) using the underlying Gauss- Newton algorithms. 2. Apply the complex RPEM algorithm to synthesized ISAR data using the above simulator. 3. Compare the performance of the proposed algorithm to standard time-frequency estimators applied to the same data sets.

  5. Observations of the marine environment from spaceborne side-looking real aperture radars

    NASA Technical Reports Server (NTRS)

    Kalmykov, A. I.; Velichko, S. A.; Tsymbal, V. N.; Kuleshov, Yu. A.; Weinman, J. A.; Jurkevich, I.

    1993-01-01

    Real aperture, side looking X-band radars have been operated from the Soviet Cosmos-1500, -1602, -1766 and Ocean satellites since 1984. Wind velocities were inferred from sea surface radar scattering for speeds ranging from approximately 2 m/s to those of hurricane proportions. The wind speeds were within 10-20 percent of the measured in situ values, and the direction of the wind velocity agreed with in situ direction measurements within 20-50 deg. Various atmospheric mesoscale eddies and tropical cyclones were thus located, and their strengths were inferred from sea surface reflectivity measurements. Rain cells were observed over both land and sea with these spaceborne radars. Algorithms to retrieve rainfall rates from spaceborne radar measurements were also developed. Spaceborne radars have been used to monitor various marine hazards. For example, information derived from those radars was used to plan rescue operations of distressed ships trapped in sea ice. Icebergs have also been monitored, and oil spills were mapped. Tsunamis produced by underwater earthquakes were also observed from space by the radars on the Cosmos 1500 series of satellites. The Cosmos-1500 satellite series have provided all weather radar imagery of the earths surface to a user community in real time by means of a 137.4 MHz Automatic Picture Transmission channel. This feature enabled the radar information to be used in direct support of Soviet polar maritime activities.

  6. The optimal polarizations for achieving maximum contrast in radar images

    NASA Technical Reports Server (NTRS)

    Swartz, A. A.; Yueh, H. A.; Kong, J. A.; Novak, L. M.; Shin, R. T.

    1988-01-01

    There is considerable interest in determining the optimal polarizations that maximize contrast between two scattering classes in polarimetric radar images. A systematic approach is presented for obtaining the optimal polarimetric matched filter, i.e., that filter which produces maximum contrast between two scattering classes. The maximization procedure involves solving an eigenvalue problem where the eigenvector corresponding to the maximum contrast ratio is an optimal polarimetric matched filter. To exhibit the physical significance of this filter, it is transformed into its associated transmitting and receiving polarization states, written in terms of horizontal and vertical vector components. For the special case where the transmitting polarization is fixed, the receiving polarization which maximizes the contrast ratio is also obtained. Polarimetric filtering is then applies to synthetic aperture radar images obtained from the Jet Propulsion Laboratory. It is shown, both numerically and through the use of radar imagery, that maximum image contrast can be realized when data is processed with the optimal polarimeter matched filter.

  7. Space Radar Image of Moscow, Russia

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a vertically polarized L-band image of the southern half of Moscow, an area which has been inhabited for 2,000 years. The image covers a diameter of approximately 50 kilometers (31 miles) and was taken on September 30, 1994 by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar aboard the space shuttle Endeavour. The city of Moscow was founded about 750 years ago and today is home to about 8 million residents. The southern half of the circular highway (a road that looks like a ring) can easily be identified as well as the roads and railways radiating out from the center of the city. The city was named after the Moskwa River and replaced Russia's former capital, St. Petersburg, after the Russian Revolution in 1917. The river winding through Moscow shows up in various gray shades. The circular structure of many city roads can easily be identified, although subway connections covering several hundred kilometers are not visible in this image. The white areas within the ring road and outside of it are buildings of the city itself and it suburban towns. Two of many airports are located in the west and southeast of Moscow, near the corners of the image. The Kremlin is located north just outside of the imaged city center. It was actually built in the 16th century, when Ivan III was czar, and is famous for its various churches. In the surrounding area, light gray indicates forests, while the dark patches are agricultural areas. The various shades from middle gray to dark gray indicate different stages of harvesting, ploughing and grassland. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific

  8. Multibaseline polarimetric synthetic aperture radar tomography of forested areas using wavelet-based distribution compressive sensing

    NASA Astrophysics Data System (ADS)

    Liang, Lei; Li, Xinwu; Gao, Xizhang; Guo, Huadong

    2015-01-01

    The three-dimensional (3-D) structure of forests, especially the vertical structure, is an important parameter of forest ecosystem modeling for monitoring ecological change. Synthetic aperture radar tomography (TomoSAR) provides scene reflectivity estimation of vegetation along elevation coordinates. Due to the advantages of super-resolution imaging and a small number of measurements, distribution compressive sensing (DCS) inversion techniques for polarimetric SAR tomography were successfully developed and applied. This paper addresses the 3-D imaging of forested areas based on the framework of DCS using fully polarimetric (FP) multibaseline SAR interferometric (MB-InSAR) tomography at the P-band. A new DCS-based FP TomoSAR method is proposed: a new wavelet-based distributed compressive sensing FP TomoSAR method (FP-WDCS TomoSAR method). The method takes advantage of the joint sparsity between polarimetric channel signals in the wavelet domain to jointly inverse the reflectivity profiles in each channel. The method not only allows high accuracy and super-resolution imaging with a low number of acquisitions, but can also obtain the polarization information of the vertical structure of forested areas. The effectiveness of the techniques for polarimetric SAR tomography is demonstrated using FP P-band airborne datasets acquired by the ONERA SETHI airborne system over a test site in Paracou, French Guiana.

  9. On the detection of crevasses in glacial ice with synthetic-aperture radar.

    SciTech Connect

    Brock, Billy C.

    2010-02-01

    The intent of this study is to provide an analysis of the scattering from a crevasse in Antarctic ice, utilizing a physics-based model for the scattering process. Of primary interest is a crevasse covered with a snow bridge, which makes the crevasse undetectable in visible-light images. It is demonstrated that a crevasse covered with a snow bridge can be visible in synthetic-aperture-radar (SAR) images. The model of the crevasse and snow bridge incorporates a complex dielectric permittivity model for dry snow and ice that takes into account the density profile of the glacier. The surface structure is based on a fractal model that can produce sastrugi-like features found on the surface of Antarctic glaciers. Simulated phase histories, computed with the Shooting and Bouncing Ray (SBR) method, are processed into SAR images. The viability of the SBR method for predicting scattering from a crevasse covered with a snow bridge is demonstrated. Some suggestions for improving the model are given.

  10. Ocean-ice interaction in the marginal ice zone using synthetic aperture radar imagery

    NASA Technical Reports Server (NTRS)

    Liu, Antony K.; Peng, Chich Y.; Weingartner, Thomas J.

    1994-01-01

    Ocean-ice interaction processes in the marginal ice zone (MIZ) by wind, waves, and mesoscale features, such as up/downwelling and eddies are studied using Earth Remote-Sensing Satellite (ERS) 1 synthetic aperture radar (SAR) images and an ocean-ice interaction model. A sequence of seven SAR images of the MIZ in the Chukchi Sea with 3 or 6 days interval are investigated for ice edge advance/retreat. Simultaneous current measurements from the northeast Chukchi Sea, as well as the Barrow wind record, are used to interpret the MIZ dynamics. SAR spectra of waves in ice and ocean waves in the Bering and Chukchi Sea are compared for the study of wave propagation and dominant SAR imaging mechanism. By using the SAR-observed ice edge configuration and wind and wave field in the Chukchi Sea as inputs, a numerical simulation has been performed with the ocean-ice interaction model. After 3 days of wind and wave forcing the resulting ice edge configuration, eddy formation, and flow velocity field are shown to be consistent with SAR observations.

  11. Agricultural crop harvest progress monitoring by fully polarimetric synthetic aperture radar imagery

    NASA Astrophysics Data System (ADS)

    Yang, Hao; Zhao, Chunjiang; Yang, Guijun; Li, Zengyuan; Chen, Erxue; Yuan, Lin; Yang, Xiaodong; Xu, Xingang

    2015-01-01

    Dynamic mapping and monitoring of crop harvest on a large spatial scale will provide critical information for the formulation of optimal harvesting strategies. This study evaluates the feasibility of C-band polarimetric synthetic aperture radar (PolSAR) for monitoring the harvesting progress of oilseed rape (Brassica napus L.) fields. Five multitemporal, quad-pol Radarsat-2 images and one optical ZY-1 02C image were acquired over a farmland area in China during the 2013 growing season. Typical polarimetric signatures were obtained relying on polarimetric decomposition methods. Temporal evolutions of these signatures of harvested fields were compared with the ones of unharvested fields in the context of the entire growing cycle. Significant sensitivity was observed between the specific polarimetric parameters and the harvest status of oilseed rape fields. Based on this sensitivity, a new method that integrates two polarimetric features was devised to detect the harvest status of oilseed rape fields using a single image. The validation results are encouraging even for the harvested fields covered with high residues. This research demonstrates the capability of PolSAR remote sensing in crop harvest monitoring, which is a step toward more complex applications of PolSAR data in precision agriculture.

  12. Space Radar Image of Hong Kong, China

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is an X-SAR image spanning an area of approximately 20 kilometers by 40 kilometers (12 miles by 25 miles) of the island of Hong Kong, the Kowloon Peninsula and the new territories in southern China, taken by the imaging radar on board the space shuttle Endeavour on October 4, 1994. North is toward the top left corner of the image. The Kaitak Airport runway on Kowloon Peninsula (center right of image) was built on reclaimed land and extends almost 3 kilometers (nearly 2 miles) into Victoria Harbor. To the south of the harbor lies the island of Hong Kong. The bright areas around the harbor are the major residential and business districts. Housing more than six million residents, Hong Kong is the most densely populated area in the world. The large number of objects visible in the harbor and surrounding waters are a variety of sea-going vessels, anchored in one of the busiest seaports in the Far East. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI), with the Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.V.(DLR), the major partner in

  13. Spaceborne Synthetic Aperture Radar (SAR) Doppler anomalies due to volcanic eruption induced phenomena

    NASA Astrophysics Data System (ADS)

    de Michele, Marcello; Raucoules, Daniel; Minet, Christian

    2015-04-01

    In the frame of the EU funded "MEDSUV" supersite project, we use multiple SAR data to investigate Doppler anomalies in the SAR signal occurring during volcanic eruptions. In Synthetic Aperture Radar, variations in the Electro Magnetic Waves travel time results in a change in the Doppler frequency that adds up to the one that is naturally generated by the relative motion between the platform and the ground targets. Within the SAR system, frequencies modulations control the image focusing along the two fundamental SAR directions, the azimuth (i.e. the platform motion direction) and the range (i. e. the sensor looking direction). During the synthetic aperture process (the so called image focusing) a target on the surface is seen along different paths. In standard focusing processing it is assumed both that ground targets are stationary and that between the sensor and the target the medium is the vacuum or a totally homogeneous medium. Therefore, if there is a significant path delay variation along the paths to a specific target this can result either in image defocusing or in pixel misregistration or both. It has been shown that SAR Doppler history anomalies can occur over volcanic areas. The goal of this study is to highlight Doppler history anomalies occurring during the SAR image formation over active volcanoes on a number of test cases. To do so, we apply a sub-aperture cross correlation algorithm on Single Look Complex data. Practically, we measure any pixel misregistration between two sub-looks of the same SAR acquisition. If a pixel shift occurs, it means that the expected radar wave path has been lengthened (or shortened) during the time when ground surface scatterers were illuminated by the sensor radiation either by a ground feature velocity (e. g. water flows, vehicles) or it is refracted by a strong medium discontinuity in the air (volcanic ash plume?). If a Doppler history anomaly is detected by the sub-aperture cross correlation, we try to explore

  14. Three-dimensional imaging using differential synthetic aperture interferometry

    NASA Astrophysics Data System (ADS)

    Zhang, Ning; Zhou, Yu; Sun, Jianfeng; Zhi, Ya'nan; Lu, Zhiyong; Xu, Qian; Sun, Zhiwei; Liu, Liren

    2014-09-01

    Synthetic aperture radar interferometry (InSAR) can gain three-dimensional topography with high spatial resolution and height accuracy using across track interferometry[1]. Conventional InSAR produce three-dimensional images from SAR data. But when the working wavelength transit from microwave to optical wave, the transmission antenna and receive antenna become very sensitive to platform vibration and beam quality[2]. Through differential receive antenna formation, we can relax the requirement of platform and laser using synthetic aperture imaging ladar (SAIL) concept[3]. Line-of-sight motion constraints are reduced by several orders of magnitude. We introduce two distinctive forms of antenna formation according to the position of interferogram. The first architecture can simplify the interferogram processing and phase extraction algorithm under time-division multiplex operation. The second architecture can process the 2D coordinate and height coordinate at the same time. Using optical diffraction theory, a systematic theory of side-looking SAIL is mathematically formulated and the necessary conditions for assuring a correct phase history are established[4]. Based on optical transformation and regulation of wavefront, a side-looking SAIL of two distinctive architectures is invented and the basic principle, systematic theory, design equations and necessary conditions are presented. It is shown that high height accuracy can be reached and the influences from atmospheric turbulence and unmodeled line-of-sight motion can be automatically compensated.

  15. Dual-sided coded-aperture imager

    DOEpatents

    Ziock, Klaus-Peter

    2009-09-22

    In a vehicle, a single detector plane simultaneously measures radiation coming through two coded-aperture masks, one on either side of the detector. To determine which side of the vehicle a source is, the two shadow masks are inverses of each other, i.e., one is a mask and the other is the anti-mask. All of the data that is collected is processed through two versions of an image reconstruction algorithm. One treats the data as if it were obtained through the mask, the other as though the data is obtained through the anti-mask.

  16. Obstacle penetrating dynamic radar imaging system

    DOEpatents

    Romero, Carlos E.; Zumstein, James E.; Chang, John T.; Leach, Jr.. Richard R.

    2006-12-12

    An obstacle penetrating dynamic radar imaging system for the detection, tracking, and imaging of an individual, animal, or object comprising a multiplicity of low power ultra wideband radar units that produce a set of return radar signals from the individual, animal, or object, and a processing system for said set of return radar signals for detection, tracking, and imaging of the individual, animal, or object. The system provides a radar video system for detecting and tracking an individual, animal, or object by producing a set of return radar signals from the individual, animal, or object with a multiplicity of low power ultra wideband radar units, and processing said set of return radar signals for detecting and tracking of the individual, animal, or object.

  17. Space Radar Image of Mt. Rainer, Washington

    NASA Technical Reports Server (NTRS)

    1994-01-01

    This is a radar image of Mount Rainier in Washington state. The volcano last erupted about 150 years ago and numerous large floods and debris flows have originated on its slopes during the last century. Today the volcano is heavily mantled with glaciers and snowfields. More than 100,000 people live on young volcanic mudflows less than 10,000 years old and, consequently, are within the range of future, devastating mudslides. This image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on its 20th orbit on October 1, 1994. The area shown in the image is approximately 59 kilometers by 60 kilometers (36.5 miles by 37 miles). North is toward the top left of the image, which was composed by assigning red and green colors to the L-band, horizontally transmitted and vertically, and the L-band, horizontally transmitted and vertically received. Blue indicates the C-band, horizontally transmitted and vertically received. In addition to highlighting topographic slopes facing the space shuttle, SIR-C records rugged areas as brighter and smooth areas as darker. The scene was illuminated by the shuttle's radar from the northwest so that northwest-facing slopes are brighter and southeast-facing slopes are dark. Forested regions are pale green in color; clear cuts and bare ground are bluish or purple; ice is dark green and white. The round cone at the center of the image is the 14,435-foot (4,399-meter) active volcano, Mount Rainier. On the lower slopes is a zone of rock ridges and rubble (purple to reddish) above coniferous forests (in yellow/green). The western boundary of Mount Rainier National Park is seen as a transition from protected, old-growth forest to heavily logged private land, a mosaic of recent clear cuts (bright purple/blue) and partially regrown timber plantations (pale blue). The prominent river seen curving away from the mountain at the top of the image (to the northwest) is the

  18. Stereoscopic full aperture imaging in nuclear medicine

    NASA Astrophysics Data System (ADS)

    Strocovsky, Sergio G.; Otero, Dino

    2011-06-01

    Images of planar scintigraphy and single photon emission computerized tomography (SPECT) used in nuclear medicine are often low quality. They usually appear to be blurred and noisy. This problem is due to the low spatial resolution and poor sensitivity of the acquisition technique with the gamma camera (GC). Other techniques, such as coded aperture imaging (CAI) reach higher spatial resolutions than GC. However, CAI is not frequently used for imaging in nuclear medicine, due to the decoding complexity of some images and the difficulty in controlling the noise magnitude. Summing up, the images obtained through GC are low quality and it is still difficult to implement CAI technique. A novel technique, full aperture Imaging (FAI), also uses gamma ray-encoding to obtain images, but the coding system and the method of images reconstruction are simpler than those used in CAI. In addition, FAI also reaches higher spatial resolution than GC. In this work, the principles of FAI technique and the method of images reconstruction are explained in detail. The FAI technique is tested by means of Monte Carlo simulations with filiform and spherical sources. Spatial resolution tests of GC versus FAI were performed using two different source-detector distances. First, simulations were made without interposing any material between the sources and the detector. Then, other more realistic simulations were made. In these, the sources were placed in the centre of a rectangular prismatic region, filled with water. A rigorous comparison was made between GC and FAI images of the linear filiform sources, by means of two methods: mean fluence profile graphs and correlation tests. Finally, three-dimensional capacity of FAI was tested with two spherical sources. The results show that FAI technique has greater sensitivity (>100 times) and greater spatial resolution (>2.6 times) than that of GC with LEHR collimator, in both cases, with and without attenuating material and long and short

  19. Two-dimensional synthetic aperture laser optical feedback imaging using galvanometric scanning

    NASA Astrophysics Data System (ADS)

    Witomski, Arnaud; Lacot, Eric; Hugon, Olivier; Jacquin, Olivier

    2008-02-01

    We have improved the resolution of our laser optical feedback imaging (LOFI) setup by using a synthetic aperture (SA) process. We report a two-dimensional (2D) SA LOFI experiment where the unprocessed image (i.e., the classical LOFI image) is obtained point by point, line after line using full 2D galvanometric scanning. The 2D superresolved image is then obtained by successively computing two angular SA operations while a one-dimensional angular synthesis is preceded by a frequency synthesis to obtain a 2D superresolved image conventionally in the synthetic aperture radar (SAR) method and their corresponding laser method called synthetic aperture ladar. The numerical and experimental results are compared.

  20. Surface Ruptures and Building Damage of the 2003 Bam, Iran, Earthquake Mapped by Satellite Synthetic Aperture Radar Interferometric Correlation

    NASA Technical Reports Server (NTRS)

    Fielding, Eric J.; Talebian, M.; Rosen, P. A.; Nazari, H.; Jackson, J. A.; Ghorashi, M.; Walker, R.

    2005-01-01

    We use the interferometric correlation from Envisat synthetic aperture radar (SAR) images to map the details of the surface ruptures related to the 26 December 2003 earthquake that devastated Bam, Iran. The main strike-slip fault rupture south of the city of Bam has a series of four segments with left steps shown by a narrow line of low correlation in the coseismic interferogram. This also has a clear expression in the field because of the net extension across the fault. Just south of the city limits, the surface strain becomes distributed over a width of about 500 m, probably because of a thicker layer of soft sedimentary material.

  1. Synthetic Aperture Radar (sar) and Optical Imagery Data Fusion: Crop Yield Analysis in Southeast Asia

    NASA Astrophysics Data System (ADS)

    Parks, S. M.

    2012-08-01

    With the expanding energy crisis and rising food prices, crop yield analysis in Southeast Asia is an increasingly important topic in this region. Rice is the most important food crop in Southeast Asia and the ability to accurately predict crop yields during a growing season is useful for decision-makers, aid providers, and commercial trade organizations. The use of optical satellite image data by itself is difficult due to the almost constant cloud in many parts of Southeast Asia. However, Synthetic Aperture Radar (SAR), or SAR data, which can image the Earth's surface through cloud cover, is suitable for many agricultural purposes, such as the detection of rice fields, and the identification of different crop species. Crop yield analysis is difficult in this region due to many factors. Rice cropping systems are often characterized by the type of rice planted, the size of rice field, the sowing dates for different fields, different types of rice cropping systems from one area to another, as well as cultural practices such as sowing and transplanting. This paper will discuss the use of SAR data fused with optical imagery to improve the ability to perform crop yield analysis on rice crops in Southeast Asia.

  2. Characterizing geolocation ambiguity responses in synthetic aperture radar: ground moving target indication

    NASA Astrophysics Data System (ADS)

    Holston, Matthew E.; Minardi, Michael J.; Temple, Michael A.; Saville, Michael A.

    2007-04-01

    Single-channel synthetic aperture radar (SAR) can provide high quality, focused images of moving targets by utilizing advanced SAR-GMTI techniques that focus all constant velocity targets into a three-dimensional space indexed by range, cross-range and cross-range velocity. However, an inherent geolocation ambiguity exists in that multiple, distinct moving targets may posses identical range versus time responses relative to a constant velocity collection platform. Although these targets are uniquely located within a four-dimensional space (x-position, y-position, x-velocity, and y-velocity), their responses are focused and mapped to the same three-dimensional position in the SAR-GMTI image cube. Previous research has shown that circular SAR (CSAR) collection geometry is one way to break this ambiguity and creates a four-dimensional detection space. This research determines the target resolution available in the detection space as a function of different collection parameters. A metric is introduced to relate the resolvability of multiple target responses for various parametric combinations, i.e., changes in key collection parameters such as integration time, slant range, look angle, and carrier frequency.

  3. Synthetic aperture radar imagery of airports and surrounding areas: Philadelphia Airport

    NASA Technical Reports Server (NTRS)

    Onstott, Robert G.; Gineris, Denise J.

    1990-01-01

    The statistical description of ground clutter at an airport and in the surrounding area is addressed. These data are being utilized in a program to detect microbursts. Synthetic Aperture Radar (SAR) data were collected at the Philadelphia Airport. These data and the results of the clutter study are described. This 13 km x 10 km scene was imaged at 9.38 GHz and HH-polarization and contained airport grounds and facilities (6 percent), industrial (14 percent), residential (14 percent), fields (10 percent), forest (8 percent), and water (33 percent). Incidence angles ranged from 40 to 84 deg. Even at the smallest incidence angles, the distributed targets such as forest, fields, water, and residential rarely had mean scattering coefficients greater than -10 dB. Eighty-seven percent of the image had scattering coefficients less than -17.5 dB. About 1 percent of the scattering coefficients exceeded 0 dB, with about 0.1 percent above 10 dB. Sources which produced the largest cross sections were largely confined to the airport grounds and areas highly industrialized. The largest cross sections were produced by observing broadside large buildings surrounded by smooth surfaces.

  4. Synthetic Aperture Radar Imagery of Airports and Surrounding Areas: Denver Stapleton International Airport

    NASA Technical Reports Server (NTRS)

    Onstott, Robert G.; Gineris, Denise J.

    1990-01-01

    This is the third in a series of three reports which address the statistical description of ground clutter at an airport and in the surrounding area. These data are being utilized in a program to detect microbursts. Synthetic aperture radar (SAR) data were collected at the Denver Stapleton Airport using a set of parameters which closely match those which are anticipated to be utilized by an aircraft on approach to an airport. These data and the results of the clutter study are described. Scenes of 13 x 10 km were imaged at 9.38 GHz and HH-, VV-, and HV-polarizations, and contain airport grounds and facilities (up to 14 percent), cultural areas (more than 50 percent), and rural areas (up to 6 percent). Incidence angles range from 40 to 84 deg. At the largest depression angles the distributed targets, such as forest, fields, water, and residential, rarely had mean scattering coefficients greater than -10 dB. From 30 to 80 percent of an image had scattering coefficients less than -20 dB. About 1 to 10 percent of the scattering coefficients exceeded 0 dB, and from 0 to 1 percent above 10 dB. In examining the average backscatter coefficients at large angles, the clutter types cluster according to the following groups: (1) terminals (-3 dB), (2) city and industrial (-7 dB), (3) warehouse (-10 dB), (4) urban and residential (-14 dB), and (5) grass (-24 dB).

  5. EISCAT Aperture Synthesis Imaging (EASI _3D) for the EISCAT_3D Project

    NASA Astrophysics Data System (ADS)

    La Hoz, Cesar; Belyey, Vasyl

    2012-07-01

    Aperture Synthesis Imaging Radar (ASIR) is one of the technologies adopted by the EISCAT_3D project to endow it with imaging capabilities in 3-dimensions that includes sub-beam resolution. Complemented by pulse compression, it will provide 3-dimensional images of certain types of incoherent scatter radar targets resolved to about 100 metres at 100 km range, depending on the signal-to-noise ratio. This ability will open new research opportunities to map small structures associated with non-homogeneous, unstable processes such as aurora, summer and winter polar radar echoes (PMSE and PMWE), Natural Enhanced Ion Acoustic Lines (NEIALs), structures excited by HF ionospheric heating, meteors, space debris, and others. The underlying physico-mathematical principles of the technique are the same as the technique employed in radioastronomy to image stellar objects; both require sophisticated inversion techniques to obtain reliable images.

  6. An Autonomous Cryobot Synthetic Aperture Radar for Subsurface Exploration of Europa

    NASA Astrophysics Data System (ADS)

    Pradhan, O.; Gasiewski, A. J.

    2015-12-01

    We present the design and field testing of a forward-looking end-fire synthetic aperture radar (SAR) for the 'Very deep Autonomous Laser-powered Kilowatt-class Yo-yoing Robotic Ice Explorer' (VALKYRIE) ice-penetrating cryobot. This design demonstrates critical technologies that will support an eventual landing and ice penetrating mission to Jupiter's icy moon, Europa. Results proving the feasibility of an end-fire SAR system for vehicle guidance and obstacle avoidance in a sub-surface ice environment will be presented. Data collected by the SAR will also be used for constructing sub-surface images of the glacier which can be used for: (i) mapping of englacial features such as crevasses, moulins, and embedded liquid water and (ii) ice-depth and glacier bed analysis to construct digital elevation models (DEM) that can help in the selection of crybot trajectories and future drill sites for extracting long-term climate records. The project consists of three parts, (i) design of an array of four conformal cavity-backed log-periodic folded slot dipole array (LPFSA) antennas that form agile radiating elements, (ii) design of a radar system that includes RF signal generation, 4x4 transmit-receive antenna switching and isolation and digital SAR data processing and (iii) field testing of the SAR in melt holes. The antennas have been designed, fabricated, and lab tested at the Center for Environmental Technology (CET) at CU-Boulder. The radar system was also designed and integrated at CET utilizing rugged RF components and FPGA based digital processing. Field testing was performed in conjunction with VALKYRIE tests by Stone Aerospace in June, 2015 on Matanuska Glacier, Alaska. The antennas are designed to operate inside ice while being immersed in a thin layer of surrounding low-conductivity melt water. Small holes in the corners of the cavities allow flooding of these cavities with the same melt-water thus allowing for quarter-wavelength cavity-backed reflection. Testing of

  7. Dense Temporal and Spatial Measurement of Surface Deformation using Real-Aperture Ground-Based Radar Interferometry

    NASA Astrophysics Data System (ADS)

    Werner, C.; Wiesmann, A.; Strozzi, T.; Wegmueller, U.; Santoro, M.

    2008-12-01

    In 2007 Gamma developed a high resolution 17.2 GHz real-aperture interferometric radar capable of measuring sub-millimeter scale deformation at distances up to 8 km. This instrument can be rapidly deployed and used to perform in-situ measurements of deformation associated with landslides, glaciers, and infrastructure. The instrument utilizes a real-aperture antenna to form a narrow azimuth beam. The azimuth beam width of 0.4 degrees determines the azimuth resolution that is proportional to the distance from the radar. The elevation antenna beamwidth is 45 degrees. The radar scans the area of interest by rotation about the vertical axis at intervals of 0.1 degrees. Ranging information is obtained by 200 MHz bandwidth chirp modulation of the transmit pulse. Radar resolution is 7m in azimuth at 1 km slant range and 0.75 meters in range. These data are first processed to images in radar coordinates and subsequently transformed to terrain-geocoded map products using an auxiliary DEM. A local terrain model can also be created from interferometric analysis of images acquired from the dual receiving antennas of our instrument. These antennas are separated by 25 cm creating a spatial interferometer. We report radar observations made during the rapid draining of the Gornersee glacial lake at the confluence of the Gorner and Grenz glaciers in Switzerland. These measurements, made in cooperation with ETHZ, cover the period of 21-24 June, 2008. We observe glacier deformation correlated with the drainage event. The nearly continuous radar data exhibit diurnal variations of the influence of water vapor, and decorrelation due to melting on the glacier surface caused by solar heating. A map of LOS velocity of the glaciers visible from the Gornergrat has been produced showing velocities exceeding 300m/year. We also show observations acquired in Triesenberg, Liechtenstein of a large slope landslide moving up to 4 cm/year. Interferograms made from data acquired during January 2007 and

  8. Effects of changing rice cultural practices on C-band synthetic aperture radar backscatter using Envisat advanced synthetic aperture radar data in the Mekong River Delta

    NASA Astrophysics Data System (ADS)

    Lam-Dao, Nguyen; Le Toan, Thuy; Apan, Armando; Bouvet, Alexandre; Young, Frank; Le-van, Trung

    2009-11-01

    Changes in rice cultivation systems have been observed in the Mekong River Delta, Vietnam. Among the changes in cultural practices, the change from transplanting to direct sowing, the use of water-saving technology, and the use of high production method could have impacts on radar remote sensing methods previously developed for rice monitoring. Using Envisat (Environmental Satellite) ASAR (Advanced Synthetic Aperture Radar) data over the province of An Giang, this study showed that the radar backscattering behaviour is much different from that of the reported traditional rice. At the early stage of the season, direct sowing on fields with rough and wet soil surface provides very high backscatter values for HH (Horizontal transmit - Horizontal receive polarisation) and VV (Vertical transmit - Vertical receive polarisation) data, as a contrast compared to the very low backscatter of fields covered with water before emergence. The temporal increase of the backscatter is therefore not observed clearly over direct sowing fields. Hence, the use of the intensity temporal change as a rice classifier proposed previously may not apply. Due to the drainage that occurs during the season, HH, VV and HH/VV are not strongly related to biomass, in contrast with past results. However, HH/VV ratio could be used to derive the rice/non-rice classification algorithm for all conditions of rice fields in the test province. The mapping results using the HH/VV polarization ratio at a single date in the middle period of the rice season were assessed using statistical data at different districts in the province, where very high accuracy was found. The method can be applied to other regions, provided that the synthetic aperture radar data are acquired during the peak period of the rice season, and that few training fields provide adjusted threshold values used in the method.

  9. Analysis of the Greenland Ice Sheet's surface hydrology using Synthetic Aperture Radar imagery

    NASA Astrophysics Data System (ADS)

    Miles, Katie; Benedek, Corinne; Tedesco, Marco; Willis, Ian

    2016-04-01