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Sample records for del sar debido

  1. Evolution of unrest at Laguna del Maule volcanic field (Chile) from InSAR and GPS measurements, 2003 to 2014

    NASA Astrophysics Data System (ADS)

    Le Mével, Hélène; Feigl, Kurt L.; Córdova, Loreto; DeMets, Charles; Lundgren, Paul

    2015-08-01

    The Laguna del Maule (LdM) volcanic field in the southern volcanic zone of the Chilean Andes exhibits a large volume of rhyolitic material erupted during postglacial times (20-2 ka). Since 2007, LdM has experienced an unrest episode characterized by high rates of deformation. Analysis of new GPS and Interferometric Synthetic Aperture Radar (InSAR) data reveals uplift rates greater than 190 mm/yr between January 2013 and November 2014. The geodetic data are modeled as an inflating sill at depth. The results are used to calculate the temporal evolution of the vertical displacement. The best time function for modeling the InSAR data set is a double exponential model with rates increasing from 2007 through 2010 and decreasing slowly since 2010. We hypothesize that magma intruding into an existing silicic magma reservoir is driving the surface deformation. Modeling historical uplift at Yellowstone, Long Valley, and Three Sisters volcanic fields suggests a common temporal evolution of vertical displacement rates.

  2. SARS Basics

    MedlinePlus

    ... waiting room or office. Top of Page CDC’s response to SARS during the 2003 outbreak CDC worked ... Center to provide round-the-clock coordination and response. Committed more than 800 medical experts and support ...

  3. SiSAR: advanced SAR simulation

    NASA Astrophysics Data System (ADS)

    Klaus, Ferdinand

    1995-11-01

    SiSAR was planned as a realistic as possible, modular, user-friendly and fast SAR raw data simulator running on ordinary workstations. Interest in (interferometric) SAR products is growing on an international scale. There is a concentration of manpower and financial resources. Dead ends, respectively failures, have to be avoided during design and mission of every SAR project by simulating the system thoroughly before the experiment. Another reason to make use of extensive reproducible simulations during design and development is the reduction of time and manpower costs. As it comes down to verifying and comparing different processing algorithms we see that (interferometric) SAR simulation is an indispensable tool for testing individual processing steps. SiSAR is a modular SAR raw data simulator for realistic description of the functions of a SAR-system. It contains an implementation of diverse models to characterize radar targets, various approaches to describe the trajectory and the motion of the footprint on the target surface and different raw data formation algorithms. Beyond there is a wide supply of tools for manipulation, analysis and user-friendly simulation handling. Results obtained by SiSAR and some first simulated interferometric SAR raw data are shown in the paper.

  4. Severe acute respiratory syndrome (SARS)

    MedlinePlus

    ... when the virus spread from small mammals in China. When someone with SARS coughs or sneezes, infected ... causes SARS include: Antibody tests for SARS Direct isolation of the SARS virus Rapid polymerase chain reaction ( ...

  5. SAR Product Control Software

    NASA Astrophysics Data System (ADS)

    Meadows, P. J.; Hounam, D.; Rye, A. J.; Rosich, B.; Börner, T.; Closa, J.; Schättler, B.; Smith, P. J.; Zink, M.

    2003-03-01

    As SAR instruments and their operating modes become more complex, as new applications place more and more demands on image quality and as our understanding of their imperfections becomes more sophisticated, there is increasing recognition that SAR data quality has to be controlled more completely to keep pace. The SAR product CONtrol software (SARCON) is a comprehensive SAR product control software suite tailored to the latest generation of SAR sensors. SARCON profits from the most up-to-date thinking on SAR image performance derived from other spaceborne and airborne SAR projects and is based on the newest applications. This paper gives an overview of the structure and the features of this new software tool, which is a product of a co-operation between teams at BAE SYSTEMS Advanced Technology Centre and DLR under contract to ESA (ESRIN). Work on SARCON began in 1999 and is continuing.

  6. SAR change detection MTI

    NASA Astrophysics Data System (ADS)

    Scarborough, Steven; Lemanski, Christopher; Nichols, Howard; Owirka, Gregory; Minardi, Michael; Hale, Todd

    2006-05-01

    This paper examines the theory, application, and results of using single-channel synthetic aperture radar (SAR) data with Moving Reference Processing (MRP) to focus and geolocate moving targets. Moving targets within a standard SAR imaging scene are defocused, displaced, or completely missing in the final image. Building on previous research at AFRL, the SAR-MRP method focuses and geolocates moving targets by reprocessing the SAR data to focus the movers rather than the stationary clutter. SAR change detection is used so that target detection and focusing is performed more robustly. In the cases where moving target returns possess the same range versus slow-time histories, a geolocation ambiguity results. This ambiguity can be resolved in a number of ways. This paper concludes by applying the SAR-MRP method to high-frequency radar measurements from persistent continuous-dwell SAR observations of a moving target.

  7. SAR antenna calibration techniques

    NASA Technical Reports Server (NTRS)

    Carver, K. R.; Newell, A. C.

    1978-01-01

    Calibration of SAR antennas requires a measurement of gain, elevation and azimuth pattern shape, boresight error, cross-polarization levels, and phase vs. angle and frequency. For spaceborne SAR antennas of SEASAT size operating at C-band or higher, some of these measurements can become extremely difficult using conventional far-field antenna test ranges. Near-field scanning techniques offer an alternative approach and for C-band or X-band SARs, give much improved accuracy and precision as compared to that obtainable with a far-field approach.

  8. SAR calibration technology review

    NASA Technical Reports Server (NTRS)

    Walker, J. L.; Larson, R. W.

    1981-01-01

    Synthetic Aperture Radar (SAR) calibration technology including a general description of the primary calibration techniques and some of the factors which affect the performance of calibrated SAR systems are reviewed. The use of reference reflectors for measurement of the total system transfer function along with an on-board calibration signal generator for monitoring the temporal variations of the receiver to processor output is a practical approach for SAR calibration. However, preliminary error analysis and previous experimental measurements indicate that reflectivity measurement accuracies of better than 3 dB will be difficult to achieve. This is not adequate for many applications and, therefore, improved end-to-end SAR calibration techniques are required.

  9. SARS/avian coronaviruses.

    PubMed

    Monceyron Jonassen, C

    2006-01-01

    In the hunt for the aetiology of the SARS outbreak in 2003, a newly developed virus DNA micro-array was successfully used to hybridise PCR products obtained by random amplification of nucleic acids extracted from a cell culture infected with material from a SARS patient. The SARS agent was found to hybridise with micro-array probes from both coronaviruses and astroviruses, but one of the coronavirus probes and the four astrovirus probes contained redundant sequences, spanning a highly conserved motif, named s2m, found at the 3' end of the genomes of almost all astroviruses, one picornavirus, and the poultry coronaviruses. The three other coronavirus probes, that hybridised with the SARS agent, were located in the replicase gene, and it could be concluded that the SARS agent was a novel coronavirus, harbouring s2m. The presence of this motif in different virus families is probably the result of recombinations between unrelated viruses, but its presence in both poultry and SARS coronaviruses could suggest a bird involvement in the history of the SARS coronavirus. A recent screening of wild birds for the presence of coronaviruses, using a pan-coronavirus RT-PCR, led to the identification of novel coronaviruses in the three species studied. Phylogenetic analyses performed on both replicase gene and nucleocapsid protein could not add support to a close relationship between avian and SARS coronaviruses, but all the novel avian coronaviruses were found to harbour s2m. The motif is inserted at a homologous place in avian and SARS coronavirus genomes, but in a somewhat different context for the SARS coronavirus. If the presence of s2m in these viruses is a result of two separate recombination events, this suggests that its particular position in these genomes is the only one that would not be deleterious for coronaviral replication, or that it is the result of a copy-choice recombination between coronaviruses, following an ancestral introduction in the coronavirus family by

  10. SAR calibration: A technology review

    NASA Technical Reports Server (NTRS)

    Larson, R. W.; Politis, D. T.; Shuchman, R. A.

    1983-01-01

    Various potential applications of amplitude-calibrated SAR systems are briefly described, along with an estimate of calibration performance requirements. A review of the basic SAR calibration problem is given. For background purposes and to establish consistent definition of terms, various conventional SAR performance parameters are reviewed along with three additional parameters which are directly related to calibrated SAR systems. Techniques for calibrating a SAR are described. Included in the results presented are: calibration philosophy and procedures; review of the calibration signal generator technology development with results describing both the development of instrumentation and internal calibration measurements for two SAR systems; summary of analysis and measurements required to determine optimum retroreflector design and configuration for use as a reference for the absolute calibration of a SAR system; and summary of techniques for in-flight measurements of SAR antenna response.

  11. Segmentation Of Polarimetric SAR Data

    NASA Technical Reports Server (NTRS)

    Rignot, Eric J. M.; Chellappa, Rama

    1994-01-01

    Report presents one in continuing series of studies of segmentation of polarimetric synthetic-aperture-radar, SAR, image data into regions. Studies directed toward refinement of method of automated analysis of SAR data.

  12. PHARUS airborne SAR concept

    NASA Astrophysics Data System (ADS)

    Snoeij, Paul; Pouwels, Henk; Koomen, Peter J.; Hoogeboom, Peter

    1995-11-01

    PHARUS (phased array universal SAR) is an airborne SAR concept which is being developed in the Netherlands. The PHARUS system differs from other airborne SARs by the use of a phased array antenna, which provides both for the flexibility in the design as well as for a compact, light-weight instrument that can be carried on small aircraft. The concept allows for the construction of airborne SAR systems on a common generic basis but tailored to specific user needs and can be seen as a preparation for future spaceborne SAR systems using solid state transmitters with electronically steerable phased array antenna. The whole approach is aimed at providing an economic and yet technically sophisticated solution to remote sensing or surveying needs of a specific user. The solid state phased array antenna consists of a collection of radiating patches; the design flexibility for a large part resides in the freedom to choose the number of patches, and thereby the essential radar performance parameters such as resolution and swath width. Another consequence of the use of the phased array antenna is the system's compactness and the possibility to rigidly mount it on a small aircraft. The use of small aircraft of course considerably improves the cost/benefit ratio of the use of airborne SAR. Flight altitude of the system is flexible between about 7,000 and 40,000 feet, giving much operational freedom within the meteo and airspace control limits. In the PHARUS concept the airborne segment is complemented by a ground segment, which consists of a SAR processor, possibly extended by a matching image processing package. (A quick look image is available in real-time on board the aircraft.) The SAR processor is UNIX based and runs on easily available hardware (SUN station). Although the additional image processing software is available, the SAR processing software is nevertheless designed to be able to interface with commercially available image processing software, as well as being able

  13. Errores fotométricos debido al uso del filtro anular de mediana en imágenes CCD

    NASA Astrophysics Data System (ADS)

    Gil-Hutton, R.; Cañada, M.; Noel, N.

    El filtro anular de mediana tiene la importante propiedad de tener una escala claramente definida, lo que permite remover de una imagen CCD todos los objetos con tamaños menores a esta escala, independientemente de su morfología particular, y reemplazarlos por el correspondiente ``background" local. Este filtro es de gran utilidad para remover gradientes de fondo, ``fringing" y halos de objetos extendidos mediante el simple procedimiento de restar a la imagen original una imagen filtrada, repitiendo el proceso las veces que sea necesario. En este trabajo se presentan resultados sobre los errores que introduce este filtro en la fotometría de objetos con diferente relación S/N y su aplicación a imágenes con gradientes de fondo y ``fringing".

  14. Polarization effects and multipolarization SAR

    NASA Technical Reports Server (NTRS)

    Freeman, Anthony

    1992-01-01

    Imaging radar polarimeters are usually implemented using a Synthetic Aperture Radar (SAR) approach to give a high resolution image in two dimensions: range and azimuth. For each pixel in the image a polarimetric SAR gives sufficient information to characterize the polarimetric scattering properties of the imaged area (or target) as seen by the radar. Using a polarimetric SAR system as opposed to a single-polarization SAR system provides significantly more information about the target scattering mechanisms and allows better discrimination between different types of surfaces. In these notes a brief overview of SAR polarimetry is offered. The notes are intended as a text to accompany a lecture on SAR polarimetry as part of an AGARD-NATO course. Covered in the notes are the following: the polarization properties of electromagnetic waves; the concepts of radar scattering and measuring radar backscatter with a SAR; polarization synthesis; scattering matrix, Stokes matrix, and covariance matrix representations of polarimetric SAR data; polarization signature plots; design and calibration of polarimetric SAR systems; polarization filtering for target detection; fitting a simple model to polarimetric SAR measurements of naturally occurring features; and supervised classification of polarimetric SAR data.

  15. Understanding SARS with Wolfram approach.

    PubMed

    Li, Da-Wei; Pan, Yu-Xi; Duan, Yun; Hung, Zhen-De; Xu, Ming-Qing; He, Lin

    2004-01-01

    Stepping acquired immunodeficiency syndrome (AIDS), severe acute respiratory syndrome (SARS) as another type of disease has been threatening mankind since late last year. Many scientists worldwide are making great efforts to study the etiology of this disease with different approaches. 13 species of SARS virus have been sequenced. However, most people still largely rely on the traditional methods with some disadvantages. In this work, we used Wolfram approach to study the relationship among SARS viruses and between SARS viruses and other types of viruses, the effect of variations on the whole genome and the advantages in the analysis of SARS based on this novel approach. As a result, the similarities between SARS viruses and other coronaviruses are not really higher than those between SARS viruses and non-coronaviruses. PMID:14732867

  16. Bistatic SAR: Proof of Concept.

    SciTech Connect

    Yocky, David A.; Doren, Neall E.; Bacon, Terry A.; Wahl, Daniel E.; Eichel, Paul H.; Jakowatz, Charles V,; Delaplain, Gilbert G.; Dubbert, Dale F.; Tise, Bertice L.; White, Kyle R.

    2014-10-01

    Typical synthetic aperture RADAR (SAR) imaging employs a co-located RADAR transmitter and receiver. Bistatic SAR imaging separates the transmitter and receiver locations. A bistatic SAR configuration allows for the transmitter and receiver(s) to be in a variety of geometric alignments. Sandia National Laboratories (SNL) / New Mexico proposed the deployment of a ground-based RADAR receiver. This RADAR receiver was coupled with the capability of digitizing and recording the signal collected. SNL proposed the possibility of creating an image of targets the illuminating SAR observes. This document describes the developed hardware, software, bistatic SAR configuration, and its deployment to test the concept of a ground-based bistatic SAR. In the proof-of-concept experiments herein, the RADAR transmitter will be a commercial SAR satellite and the RADAR receiver will be deployed at ground level, observing and capturing RADAR ground/targets illuminated by the satellite system.

  17. EARSEC SAR processing system

    NASA Astrophysics Data System (ADS)

    Protheroe, Mark; Sloggett, David R.; Sieber, Alois J.

    1994-12-01

    Traditionally, the production of high quality Synthetic Aperture Radar imagery has been an area where a potential user would have to expend large amounts of money in either the bespoke development of a processing chain dedicated to his requirements or in the purchase of a dedicated hardware platform adapted using accelerator boards and enhanced memory management. Whichever option the user adopted there were limitations based on the desire for a realistic throughput in data load and time. The user had a choice, made early in the purchase, for either a system that adopted innovative algorithmic manipulation, to limit the processing time of the purchase of expensive hardware. The former limits the quality of the product, while the latter excludes the user from any visibility into the processing chain. Clearly there was a need for a SAR processing architecture that gave the user a choice into the methodology to be adopted for a particular processing sequence, allowing him to decide on either a quick (lower quality) product or a detailed slower (high quality) product, without having to change the algorithmic base of his processor or the hardware platform. The European Commission, through the Advanced Techniques unit of the Joint Research Centre (JRC) Institute for Remote Sensing at Ispra in Italy, realizing the limitations on current processing abilities, initiated its own program to build airborne SAR and Electro-Optical (EO) sensor systems. This program is called the European Airborne Remote Sensing Capabilities (EARSEC) program. This paper describes the processing system developed for the airborne SAR sensor system. The paper considers the requirements for the system and the design of the EARSEC Airborne SAR Processing System. It highlights the development of an open SAR processing architecture where users have full access to intermediate products that arise from each of the major processing stages. It also describes the main processing stages in the overall

  18. SAR based adaptive GMTI

    NASA Astrophysics Data System (ADS)

    Vu, Duc; Guo, Bin; Xu, Luzhou; Li, Jian

    2010-04-01

    We consider ground moving target indication (GMTI) and target velocity estimation based on multi-channel synthetic aperture radar (SAR) images. Via forming velocity versus cross-range images, we show that small moving targets can be detected even in the presence of strong stationary ground clutter. Moreover, the velocities of the moving targets can be estimated, and the misplaced moving targets can be placed back to their original locations based on the estimated velocities. Adaptive beamforming techniques, including Capon and generalizedlikelihood ratio test (GLRT), are used to form velocity versus cross-range images for each range bin of interest. The velocity estimation ambiguities caused by the multi-channel array geometry are analyzed. We also demonstrate the effectiveness of our approaches using the Air Force Research Laboratory (AFRL) publicly-released Gotcha SAR based GMTI data set.

  19. Bayesian SAR imaging

    NASA Astrophysics Data System (ADS)

    Chen, Zhaofu; Tan, Xing; Xue, Ming; Li, Jian

    2010-04-01

    We introduce a maximum a posteriori (MAP) algorithm and a sparse learning via iterative minimization (SLIM) algorithm to synthetic aperture radar (SAR) imaging. Both MAP and SLIM are sparse signal recovery algorithms with excellent sidelobe suppression and high resolution properties. The former cyclically maximizes the a posteriori probability density function for a given sparsity promoting prior, while the latter cyclically minimizes a regularized least squares cost function. We show how MAP and SLIM can be adapted to the SAR imaging application and used to enhance the image quality. We evaluate the performance of MAP and SLIM using the simulated complex-valued backscattered data from a backhoe vehicle. The numerical results show that both MAP and SLIM satisfactorily suppress the sidelobes and yield higher resolution than the conventional matched filter or delay-and-sum (DAS) approach. MAP and SLIM outperform the widely used compressive sampling matching pursuit (CoSaMP) algorithm, which requires the delicate choice of user parameters. Compared with the recently developed iterative adaptive approach (IAA), MAP and SLIM are computationally more efficient, especially with the help of fast Fourier transform (FFT). Also, the a posteriori distribution given by the algorithms provides us with a basis for the analysis of the statistical properties of the SAR image pixels.

  20. Circular SAR GMTI

    NASA Astrophysics Data System (ADS)

    Page, Douglas; Owirka, Gregory; Nichols, Howard; Scarborough, Steven

    2014-06-01

    We describe techniques for improving ground moving target indication (GMTI) performance in multi-channel synthetic aperture radar (SAR) systems. Our approach employs a combination of moving reference processing (MRP) to compensate for defocus of moving target SAR responses and space-time adaptive processing (STAP) to mitigate the effects of strong clutter interference. Using simulated moving target and clutter returns, we demonstrate focusing of the target return using MRP, and discuss the effect of MRP on the clutter response. We also describe formation of adaptive degrees of freedom (DOFs) for STAP filtering of MRP processed data. For the simulated moving target in clutter example, we demonstrate improvement in the signal to interference plus noise (SINR) loss compared to more standard algorithm configurations. In addition to MRP and STAP, the use of tracker feedback, false alarm mitigation, and parameter estimation techniques are also described. A change detection approach for reducing false alarms from clutter discretes is outlined, and processing of a measured data coherent processing interval (CPI) from a continuously orbiting platform is described. The results demonstrate detection and geolocation of a high-value target under track. The endoclutter target is not clearly visible in single-channel SAR chips centered on the GMTI track prediction. Detections are compared to truth data before and after geolocation using measured angle of arrival (AOA).

  1. Wetland InSAR

    NASA Astrophysics Data System (ADS)

    Wdowinski, S.; Kim, S.; Amelung, F.; Dixon, T.

    2006-12-01

    Wetlands are transition zones where the flow of water, the nutrient cycling, and the sun energy meet to produce a unique and very productive ecosystem. They provide critical habitat for a wide variety of plant and animal species, including the larval stages of many ocean fish. Wetlands also have a valuable economical importance, as they filter nutrients and pollutants from fresh water used by human and provide aquatic habitats for outdoor recreation, tourism, and fishing. Globally, many such regions are under severe environmental stress, mainly from urban development, pollution, and rising sea level. However, there is increasing recognition of the importance of these habitats, and mitigation and restoration activities have begun in a few regions. A key element in wetlands conservation, management, and restoration involves monitoring its hydrologic system, as the entire ecosystem depends on its water supply. Heretofore, hydrologic monitoring of wetlands are conducted by stage (water level) stations, which provide good temporal resolution, but suffer from poor spatial resolution, as stage station are typically distributed several, or even tens of kilometers, from one another. Wetland application of InSAR provides the needed high spatial resolution hydrological observations, complementing the high temporal resolution terrestrial observations. Although conventional wisdom suggests that interferometry does not work in vegetated areas, several studies have shown that both L- and C-band interferograms with short acquisition intervals (1-105 days) can maintain excellent coherence over wetlands. In this study we explore the usage of InSAR for detecting water level changes in various wetland environments around the world, including the Everglades (south Florida), Louisiana Coast (southern US), Chesapeake Bay (eastern US), Pantanal (Brazil), Okavango Delta (Botswana), and Lena Delta (Siberia). Our main study area is the Everglades wetland (south Florida), which is covered by

  2. Recovering Seasat SAR Data

    NASA Astrophysics Data System (ADS)

    Logan, T. A.; Arko, S. A.; Rosen, P. A.

    2013-12-01

    To demonstrate the feasibility of orbital remote sensing for global ocean observations, NASA launched Seasat on June 27th, 1978. Being the first space borne SAR mission, Seasat produced the most detailed SAR images of Earth from space ever seen to that point in time. While much of the data collected in the USA was processed optically, a mere 150 scenes had been digitally processed by March 1980. In fact, only an estimated 3% of Seasat data was ever digitally processed. Thus, for over three decades, the majority of the SAR data from this historic mission has been dormant, virtually unavailable to scientists in the 21st century. Over the last year, researchers at the Alaska Satellite Facility (ASF) Distributed Active Archive Center (DAAC) have processed the Seasat SAR archives into imagery products. A telemetry decoding system was created and the data were filtered into readily processable signal files. Due to nearly 35 years of bit rot, the bit error rate (BER) for the ASF DAAC Seasat archives was on the order of 1 out of 100 to 1 out of 100,000. This extremely high BER initially seemed to make much of the data undecodable - because the minor frame numbers are just 7 bits and no range line numbers exist in the telemetry even the 'simple' tasks of tracking the minor frame number or locating the start of each range line proved difficult. Eventually, using 5 frame numbers in sequence and a handful of heuristics, the data were successfully decoded into full range lines. Concurrently, all metadata were stored into external files. Recovery of this metadata was also problematic, the BER making the information highly suspect and, initially at least, unusable in any sort of automated fashion. Because of the BER, all of the single bit metadata fields proved unreliable. Even fields that should be constant for a data take (e.g. receiving station, day of the year) showed high variability, each requiring a median filter to be usable. The most challenging, however, were the

  3. Bistatic SAR: Imagery & Image Products.

    SciTech Connect

    Yocky, David A.; Wahl, Daniel E.; Jakowatz, Charles V,

    2014-10-01

    While typical SAR imaging employs a co-located (monostatic) RADAR transmitter and receiver, bistatic SAR imaging separates the transmitter and receiver locations. The transmitter and receiver geometry determines if the scattered signal is back scatter, forward scatter, or side scatter. The monostatic SAR image is backscatter. Therefore, depending on the transmitter/receiver collection geometry, the captured imagery may be quite different that that sensed at the monostatic SAR. This document presents imagery and image products formed from captured signals during the validation stage of the bistatic SAR research. Image quality and image characteristics are discussed first. Then image products such as two-color multi-view (2CMV) and coherent change detection (CCD) are presented.

  4. Processor architecture for airborne SAR systems

    NASA Technical Reports Server (NTRS)

    Glass, C. M.

    1983-01-01

    Digital processors for spaceborne imaging radars and application of the technology developed for airborne SAR systems are considered. Transferring algorithms and implementation techniques from airborne to spaceborne SAR processors offers obvious advantages. The following topics are discussed: (1) a quantification of the differences in processing algorithms for airborne and spaceborne SARs; and (2) an overview of three processors for airborne SAR systems.

  5. Anatomy of a SAR impulse response.

    SciTech Connect

    Doerry, Armin Walter

    2007-08-01

    A principal measure of Synthetic Aperture Radar (SAR) image quality is the manifestation in the SAR image of a spatial impulse, that is, the SAR's Impulse Response (IPR). IPR requirements direct certain design decisions in a SAR. Anomalies in the IPR can point to specific anomalous behavior in the radar's hardware and/or software.

  6. Studies of ice sheet hydrology using SAR

    NASA Technical Reports Server (NTRS)

    Bindschadler, R. A.; Vornberger, P. L.

    1989-01-01

    Analysis of SAR data of the Greenland ice sheet in summer and winter suggest the use of SAR to monitor the temporal hydrology of ice sheets. Comparisons of each SAR data set with summer Landsat TM imagery show an areal-positive correlation with summer SAR data and a negative correlation with winter SAR data. It is proposed that the summer SAR data are most sensitive to the variable concentrations of free water in the surface snow and that the winter SAR data indicate variations in snow grain size.

  7. ERS-1 SAR data processing

    NASA Technical Reports Server (NTRS)

    Leung, K.; Bicknell, T.; Vines, K.

    1986-01-01

    To take full advantage of the synthetic aperature radar (SAR) to be flown on board the European Space Agency's Remote Sensing Satellite (ERS-1) (1989) and the Canadian Radarsat (1990), the implementation of a receiving station in Alaska is being studied to gather and process SAR data pertaining in particular to regions within the station's range of reception. The current SAR data processing requirement is estimated to be on the order of 5 minutes per day. The Interim Digital Sar Processor (IDP) which was under continual development through Seasat (1978) and SIR-B (1984) can process slightly more than 2 minutes of ERS-1 data per day. On the other hand, the Advanced Digital SAR Processore (ADSP), currently under development for the Shuttle Imaging Radar C (SIR-C, 1988) and the Venus Radar Mapper, (VMR, 1988), is capable of processing ERS-1 SAR data at a real time rate. To better suit the anticipated ERS-1 SAR data processing requirement, both a modified IDP and an ADSP derivative are being examined. For the modified IDP, a pipelined architecture is proposed for the mini-computer plus array processor arrangement to improve throughout. For the ADSP derivative, a simplified version is proposed to enhance ease of implementation and maintainability while maintaing real time throughput rates. These processing systems are discussed and evaluated.

  8. SAR/InSAR observation by an HF sounder

    NASA Astrophysics Data System (ADS)

    Kobayashi, T.; Ono, T.

    2007-03-01

    Application of SAR imaging algorithm to spaceborne HF sounder observation was studied. Two types of image ambiguity problems were addressed in the application. One is surface/subsurface image ambiguity arising from deep penetration of HF wave, and another is mirror image ambiguity that is inherent to dipole antenna SAR. A numerical model demonstrated that the surface/subsurface ambiguity can be mitigated by taking a synthetic aperture large enough to defocus subsurface objects. In order to resolve the mirror image ambiguity problem, an image superposition technique was proposed. The performance of the technique was demonstrated by using simulation data of the HF sounder observation to confirm the feasibility of HF SAR and HF InSAR observation.

  9. 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.

  10. Characterization of sarR, a Modulator of sar Expression in Staphylococcus aureus

    PubMed Central

    Manna, Adhar; Cheung, Ambrose L.

    2001-01-01

    The expression of virulence determinants in Staphylococcus aureus is controlled by global regulatory loci (e.g., sar and agr). The sar locus is composed of three overlapping transcripts (sar P1, P3, and P2 transcripts from P1, P3, and P2 promoters, respectively), all encoding the 372-bp sarA gene. The level of SarA, the major regulatory protein, is partially controlled by the differential activation of sar promoters. We previously partially purified a ∼12 kDa protein with a DNA-specific column containing a sar P2 promoter fragment. In this study, the putative gene, designated sarR, was identified and found to encode a 13.6-kDa protein with homology to SarA. Transcriptional and immunoblot studies revealed the sarR gene to be expressed in other staphylococcal strains. Recombinant SarR protein bound sar P1, P2, and P3 promoter fragments in gel shift and footprinting assays. A sarR mutant expressed a higher level of P1 transcript than the parent, as confirmed by promoter green fluorescent protein fusion assays. As the P1 transcript is the predominant sar transcript, we confirmed that the sarR mutant expressed more SarA than the parental strain. We thus proposed that SarR is a regulatory protein that binds to the sar promoters to down-regulate P1 transcription and the ensuing SarA protein expression. PMID:11159982

  11. Earth observing SAR data processing systems at the Jet Propulsion Laboratory - Seasat to EOS SAR

    NASA Technical Reports Server (NTRS)

    Nichols, David A.; Curlander, John C.

    1991-01-01

    The evolution of SAR digital data processing and management ground systems developed at the JPL for earth science missions is discussed. Attention is given to the SAR ground data system requirements, the early data processing systems, the Seasat SAR system, and the SIR-B data processing system. Special consideration is given to two currently operational SAR data systems: the JPL aircraft SAR processing system that flies on the NASA DC-8 and the Alaska SAR Facility at Fairbanks.

  12. SAR imaging - Seeing the unseen

    NASA Technical Reports Server (NTRS)

    Kobrick, M.

    1982-01-01

    The functional abilities and operations of synthetic aperture radar (SAR) are described. SAR employs long wavelength radio waves in bursts, imaging a target by 'listening' to the small frequency changes that result from the Doppler shift due to the relative motion of the imaging craft and the motions of the target. The time delay of the signal return allows a determination of the location of the target, leading to the build up of a two-dimensional image. The uses of both Doppler shifts and time delay enable detailed imagery which is independent of distance. The synthetic aperture part of the name of SAR derives from the beaming of multiple pulses, which result in a picture that is effectively the same as using a large antenna. Mechanisms contributing to the fineness of SAR images are outlined.

  13. SARS Antibody Test for Serosurveillance

    PubMed Central

    Hsueh, Po-Ren; Kao, Chuan-Liang; Lee, Chun-Nan; Chen, Li-Kuan; Ho, Mei-Shang; Sia, Charles; De Fang, Xin; Lynn, Shugene; Chang, Tseng Yuan; Liu, Shi Kau; Walfield, Alan M.

    2004-01-01

    A peptide-based enzyme-linked immunosorbent assay (ELISA) can be used for retrospective serosurveillance of severe acute respiratory syndrome (SARS) by helping identify undetected chains of disease transmission. The assay was developed by epitope mapping, using synthetic peptides from the spike, membrane, and nucleocapsid protein sequences of SARS-associated coronavirus. The new peptide ELISA consistently detected seroconversion by week 2 of onset of fever, and seropositivity remained through day 100. Specificity was 100% on normal blood donor samples, on serum samples associated with infection by other pathogens, and on an interference panel. The peptide-based test has advantages of safety, standardization, and automation over previous immunoassays for SARS. The assay was used for a retrospective survey of healthy healthcare workers in Taiwan who treated SARS patients. Asymptomatic seroconversions were detected in two hospitals that had nosocomial disease. PMID:15498156

  14. TerraSAR-X mission

    NASA Astrophysics Data System (ADS)

    Werninghaus, Rolf

    2004-01-01

    The TerraSAR-X is a German national SAR- satellite system for scientific and commercial applications. It is the continuation of the scientifically and technologically successful radar missions X-SAR (1994) and SRTM (2000) and will bring the national technology developments DESA and TOPAS into operational use. The space segment of TerraSAR-X is an advanced high-resolution X-Band radar satellite. The system design is based on a sound market analysis performed by Infoterra. The TerraSAR-X features an advanced high-resolution X-Band Synthetic Aperture Radar based on the active phased array technology which allows the operation in Spotlight-, Stripmap- and ScanSAR Mode with various polarizations. It combines the ability to acquire high resolution images for detailed analysis as well as wide swath images for overview applications. In addition, experimental modes like the Dual Receive Antenna Mode allow for full-polarimetric imaging as well as along track interferometry, i.e. moving target identification. The Ground Segment is optimized for flexible response to (scientific and commercial) User requests and fast image product turn-around times. The TerraSAR-X mission will serve two main goals. The first goal is to provide the strongly supportive scientific community with multi-mode X-Band SAR data. The broad spectrum of scientific application areas include Hydrology, Geology, Climatology, Oceanography, Environmental Monitoring and Disaster Monitoring as well as Cartography (DEM Generation) and Interferometry. The second goal is the establishment of a commercial EO-market in Europe which is driven by Infoterra. The commercial goal is the development of a sustainable EO-business so that the e.g. follow-on systems can be completely financed by industry from the profit. Due to its commercial potential, the TerraSAR-X project will be implemented based on a public-private partnership with the Astrium GmbH. This paper will describe first the mission objectives as well as the

  15. The X-SAR System

    NASA Technical Reports Server (NTRS)

    Oettl, Herwig

    1986-01-01

    During the past few years, there has been significant progress made in the planning for an X-band SAR, designed to fly in the shuttle together with the SIR-C system of NASA/JPL. New work and studies have been initiated to enable the goal of two missions in 1990 to be met. The antennas of X-SAR and SIR-C will be placed side-by-side on a pivoted steerable foldable structure, which will allow antenna movement without changing the attitude of the shuttle. This figure also shows the pallet, underneath the antenna structure, which houses the electronic sub-systems of both radars. Although the two radar systems, X-band SAR and the L- and C-band SAR of SIR-C, have different technical designs, their overall system performance, in terms of image quality, is expected to be similar. The current predicted performance of the X-SAR system based on results of the continuing Phase B studies is detailed. Differences between the performance parameters of X-SAR and those of SIR-C are only detailed in as far as they affect planning decisions to be made by experimenters.

  16. Lightweight SAR GMTI radar technology development

    NASA Astrophysics Data System (ADS)

    Kirk, John C.; Lin, Kai; Gray, Andrew; Hseih, Chung; Darden, Scott; Kwong, Winston; Majumder, Uttam; Scarborough, Steven

    2013-05-01

    A small and lightweight dual-channel radar has been developed for SAR data collections. Using standard Displaced Phase Center Antenna (DPCA) radar digital signal processing, SAR GMTI images have been obtained. The prototype radar weighs 5-lbs and has demonstrated the extraction of ground moving targets (GMTs) embedded in high-resolution SAR imagery data. Heretofore this type of capability has been reserved for much larger systems such as the JSTARS. Previously, small lightweight SARs featured only a single channel and only displayed SAR imagery. Now, with the advent of this new capability, SAR GMTI performance is now possible for small UAV class radars.

  17. SAR data exploitation: computational technology enabling SAR ATR algorithm development

    NASA Astrophysics Data System (ADS)

    Majumder, Uttam K.; Casteel, Curtis H., Jr.; Buxa, Peter; Minardi, Michael J.; Zelnio, Edmund G.; Nehrbass, John W.

    2007-04-01

    A fundamental issue with synthetic aperture radar (SAR) application development is data processing and exploitation in real-time or near real-time. The power of high performance computing (HPC) clusters, FPGA, and the IBM Cell processor presents new algorithm development possibilities that have not been fully leveraged. In this paper, we will illustrate the capability of SAR data exploitation which was impractical over the last decade due to computing limitations. We can envision that SAR imagery encompassing city size coverage at extremely high levels of fidelity could be processed at near-real time using the above technologies to empower the warfighter with access to critical information for the war on terror, homeland defense, as well as urban warfare.

  18. On Ambiguities in SAR Design

    NASA Technical Reports Server (NTRS)

    Freeman, Anthony

    2006-01-01

    Ambiguities are an aliasing effect caused by the periodic sampling of the scene backscatter inherent to pulsed radar systems such as Synthetic Aperture radar (SAR). In this paper we take a fresh look at the relationship between SAR range and azimuth ambiguity constraints on the allowable pulse repetition frequency (PRF) and the antenna length. We show that for high squint angles smaller antennas may be feasible in some cases. For some applications, the ability to form a synthetic aperture at high squint angles is desirable, but the size of the antenna causes problems in the design of systems capable of such operation. This is because the SAR system design is optimized for a side-looking geometry. In two examples design examples we take a suboptimum antenna size and examine the performance in terms of azimuth resolution and swath width as a function of squint angle. We show that for stripmap SARs, the swath width is usually worse for off-boresight squint angles, because it is severely limited by range walk, except in cases where we relax the spatial resolution. We consider the implications for the design of modest-resolution, narrow swath, scanning SAR scatterometers .

  19. SARS Patients and Their Close Contacts

    MedlinePlus

    ... Fact Sheet for SARS Patients and Their Close Contacts Format: Select one PDF [256 KB] Recommend on ... that are not now known. What does "close contact" mean? In the context of SARS, close contact ...

  20. Method for removing RFI from SAR images

    DOEpatents

    Doerry, Armin W.

    2003-08-19

    A method of removing RFI from a SAR by comparing two SAR images on a pixel by pixel basis and selecting the pixel with the lower magnitude to form a composite image. One SAR image is the conventional image produced by the SAR. The other image is created from phase-history data which has been filtered to have the frequency bands containing the RFI removed.

  1. Registration of interferometric SAR images

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    Interferometric synthetic aperture radar (INSAR) is a new way of performing topography mapping. Among the factors critical to mapping accuracy is the registration of the complex SAR images from repeated orbits. A new algorithm for registering interferometric SAR images is presented. A new figure of merit, the average fluctuation function of the phase difference image, is proposed to evaluate the fringe pattern quality. The process of adjusting the registration parameters according to the fringe pattern quality is optimized through a downhill simplex minimization algorithm. The results of applying the proposed algorithm to register two pairs of Seasat SAR images with a short baseline (75 m) and a long baseline (500 m) are shown. It is found that the average fluctuation function is a very stable measure of fringe pattern quality allowing very accurate registration.

  2. Monsoon '90 - Preliminary SAR results

    NASA Technical Reports Server (NTRS)

    Dubois, Pascale C.; Van Zyl, Jakob J.; Guerra, Abel G.

    1992-01-01

    Multifrequency polarimetric synthetic aperture radar (SAR) images of the Walnut Gulch watershed near Tombstone, Arizona were acquired on 28 Mar. 1990 and on 1 Aug. 1990. Trihedral corner reflectors were deployed prior to both overflights to allow calibration of the two SAR data sets. During both overflights, gravimetric soil moisture and dielectric constant measurements were made. Detailed vegetation height, density, and water content measurements were made as part of the Monsoon 1990 Experiment. Preliminary results based on analysis of the multitemporal polarimetric SAR data are presented. Only the C-band data (5.7-cm wavelength) radar images show significant difference between Mar. and Aug., with the strongest difference observed in the HV images. Based on the radar data analysis and the in situ measurements, we conclude that these differences are mainly due to changes in the vegetation and not due to the soil moisture changes.

  3. Monsoon 1990: Preliminary SAR results

    NASA Technical Reports Server (NTRS)

    Vanzyl, Jakob J.; Dubois, Pascale; Guerra, Abel

    1991-01-01

    Multifrequency polarimetric synthetic aperture radar (SAR) images of the Walnut Gulch watershed near Tombstone, Arizona were acquired on 28 Mar. 1990 and on 1 Aug. 1990. Trihedral corner reflectors were deployed prior to both overflights to allow calibration of the two SAR data sets. During both overflights, gravimetric soil moisture and dielectric constant measurements were made. Detailed vegetation height, density, and water content measurements were made as part of the Monsoon 1990 Experiment. Preliminary results based on analysis of the multitemporal polarimetric SAR data are presented. Only the C-band data (5.7-cm wavelength) radar images show significant difference between Mar. and Aug., with the strongest difference observed in the HV images. Based on the radar data analysis and the in situ measurements, we conclude that these differences are mainly due to changes in the vegetation and not due to the soil moisture changes.

  4. Registration Of SAR Images With Multisensor Images

    NASA Technical Reports Server (NTRS)

    Evans, Diane L.; Burnette, Charles F.; Van Zyl, Jakob J.

    1993-01-01

    Semiautomated technique intended primarily to facilitate registration of polarimetric synthetic-aperture-radar (SAR) images with other images of same or partly overlapping terrain while preserving polarization information conveyed by SAR data. Technique generally applicable in sense one or both of images to be registered with each other generated by polarimetric or nonpolarimetric SAR, infrared radiometry, conventional photography, or any other applicable sensing method.

  5. Progress towards SAR based ecosystem analysis

    NASA Technical Reports Server (NTRS)

    Ranson, K. Jon; Sun, Guoqing

    1991-01-01

    Recent progress towards a synthetic aperture radar (SAR) based system for determining forest ecosystem attributes is discussed. Our SAR data processing and analysis sequence, from calibration through classification, is described. In addition, the usefulness of SAR image data for identifying ecosystem classes is discussed.

  6. SAR and InSAR georeferencing algorithms for inertial navigation systems

    NASA Astrophysics Data System (ADS)

    Greco, M.; Kulpa, K.; Pinelli, G.; Samczynski, P.

    2011-10-01

    This paper presents the concept of Synthetic Aperture Radar (SAR) and Interferemetric SAR (InSAR) georeferencing algorithms dedicated for SAR based augmented Inertial Navigation Architecture (SARINA). The SARINA is a novel concept of the Inertial Navigation System (INS), which utilized the SAR radar as an additional sensor to provide information about the platform trajectory position and compensate an aircraft drift due to Inertial Measurement Unit (IMU) errors, Global Positioning System (GPS) lack of integrity, etc.

  7. Realtime processor of SAR systems

    NASA Astrophysics Data System (ADS)

    Schotter, R.

    Attention is given to potential applications of a synthetic aperture radar (SAR) real time processor which was developed for Space Shuttle-based earth sensing, and which may prove useful in military surveillance, ocean wave studies, ship movements in territorial waters, land conservation, geology, and mineralogical prospecting. The SAR processor's signal processing task is characterized by complex algorithms and large quantities of raw data/time unit. A 'pipeline' configuration has been judged optimal for this type of processing, and it will consist of digital hardware modules for Fourier transform, digital filtering, two-dimensional image memory, and complex multiplication.

  8. Squint mode SAR processing algorithms

    NASA Technical Reports Server (NTRS)

    Chang, C. Y.; Jin, M.; Curlander, J. C.

    1989-01-01

    The unique characteristics of a spaceborne SAR (synthetic aperture radar) operating in a squint mode include large range walk and large variation in the Doppler centroid as a function of range. A pointing control technique to reduce the Doppler drift and a new processing algorithm to accommodate large range walk are presented. Simulations of the new algorithm for squint angles up to 20 deg and look angles up to 44 deg for the Earth Observing System (Eos) L-band SAR configuration demonstrate that it is capable of maintaining the resolution broadening within 20 percent and the ISLR within a fraction of a decibel of the theoretical value.

  9. Polarization Filtering of SAR Data

    NASA Technical Reports Server (NTRS)

    Dubois, Pascale C.; Van Zyl, Jakob J.

    1991-01-01

    Theoretical analysis of polarization filtering of synthetic-aperture-radar (SAR) returns provide hybrid method applied to either (1) maximize signal-to-noise ratio of return from given target or (2) enhance contrast between targets of two different types (that have different polarization properties). Method valid for both point and extended targets and for both monostatic and bistatic radars as well as SAR. Polarization information in return signals provides more complete description of radar-scattering properties of targets and used to obtain additional information about targets for use in classifying them, discriminating between them, or enhancing features of radar images.

  10. Bioelectromagnetic effects measurements - SAR and induced current.

    PubMed

    Dlugosz, Tomasz

    2015-01-01

    The paper discusses several theoretical and practical aspects of the application of currents flowing through the body of a radiotelephone operator and Specific Absorption Rate (SAR). SAR is known as the physical quantity which is a perfect solution for biological experiments. Unfortunately, SAR cannot be measured directly. Contrary to SAR, which is limited to the penetration depth, a current induced in a point of a body is measurable in any other point of the body. The main objective of this paper is to show that the current induced in a human body when using a radiotelephone or mobile phone is significant and should be analyzed as widely as SAR is. Computer simulations of a human's hand with a radiotelephone were made. Experiments were also conducted. The results of the experiments show that induced current is also as important as SAR and it cannot be omitted in bioelectromagnetic experiments. In biomedical studies both parameters: induced current and SAR play a major role. PMID:25585976

  11. Further SEASAT SAR coastal ocean wave analysis

    NASA Technical Reports Server (NTRS)

    Kasischke, E. S.; Shuchman, R. A.; Meadows, G. A.; Jackson, P. L.; Tseng, Y.

    1981-01-01

    Analysis techniques used to exploit SEASAT synthetic aperture radar (SAR) data of gravity waves are discussed and the SEASAT SAR's ability to monitor large scale variations in gravity wave fields in both deep and shallow water is evaluated. The SAR analysis techniques investigated included motion compensation adjustments and the semicausal model for spectral analysis of SAR wave data. It was determined that spectra generated from fast Fourier transform analysis (FFT) of SAR wave data were not significantly altered when either range telerotation adjustments or azimuth focus shifts were used during processing of the SAR signal histories, indicating that SEASAT imagery of gravity waves is not significantly improved or degraded by motion compensation adjustments. Evaluation of the semicausal (SC) model using SEASAT SAR data from Rev. 974 indicates that the SC spectral estimates were not significantly better than the FFT results.

  12. [Severe acute respiratory syndrome (SARS)].

    PubMed

    Gillissen, Adrian; Ruf, Bernhard R

    2003-06-15

    Severe acute respiratory syndrome (SARS) is a viral disease, observed primarily in Southern China in November 2002, with variable flu-like symptoms and pneumonia, in approx. 5% leading to death from respiratory distress syndrome (RDS). The disease was spread over more than 30 states all over the globe by SARS-virus-infected travelers. WHO and CDC received first information about a new syndrome by the end of February 2003, after the first cases outside the Republic of China had been observed. A case in Hanoi, Vietnam, led to the first precise information about the new disease entity to WHO, by Dr. Carlo Urbani, a co-worker of WHO/Doctors without Borders, who had been called by local colleagues to assist in the management of a patient with an unknown severe disease by the end of February 2003. Dr. Urbani died from SARS, as did many other health care workers. In the meantime, more than 7,000 cases have been observed worldwide, predominantly in China and Hong Kong, but also in Taiwan, Canada, Singapore, and the USA, and many other countries, and more than 600 of these patients died from RDS. Since the beginning of March 2003, when WHO and CDC started their activities, in close collaboration with a group of international experts, including the Bernhard-Nocht-Institute in Hamburg and the Department of Virology in Frankfurt/Main, a previously impossible success in the disclosure of the disease was achieved. Within only 8 weeks of research it was possible to describe the infectious agent, a genetically modified coronavirus, including the genetic sequence, to establish specific diagnostic PCR methods and to find possible mechanisms for promising therapeutic approaches. In addition, intensifying classical quarantine and hospital hygiene measures, it was possible to limit SARS in many countries to sporadic cases, and to reduce the disease in countries such as Canada and Vietnam. This review article summarizes important information about many issues of SARS (May 15th, 2003

  13. Controlling Data Collection to Support SAR Image Rotation

    SciTech Connect

    Doerry, Armin W.; Cordaro, J. Thomas; Burns, Bryan L.

    2008-10-14

    A desired rotation of a synthetic aperture radar (SAR) image can be facilitated by adjusting a SAR data collection operation based on the desired rotation. The SAR data collected by the adjusted SAR data collection operation can be efficiently exploited to form therefrom a SAR image having the desired rotational orientation.

  14. Asymptomatic SARS coronavirus infection among healthcare workers, Singapore.

    PubMed

    Wilder-Smith, Annelies; Teleman, Monica D; Heng, Bee H; Earnest, Arul; Ling, Ai E; Leo, Yee S

    2005-07-01

    We conducted a study among healthcare workers (HCWs) exposed to patients with severe acute respiratory syndrome (SARS) before infection control measures were instituted. Of all exposed HCWs, 7.5% had asymptomatic SARS-positive cases. Asymptomatic SARS was associated with lower SARS antibody titers and higher use of masks when compared to pneumonic SARS. PMID:16022801

  15. The SARS-associated stigma of SARS victims in the post-SARS era of Hong Kong.

    PubMed

    Siu, Judy Yuen-man

    2008-06-01

    This article explores the disease-associated stigma attached to the SARS victims in the post-SARS era of Hong Kong. I argue that the SARS-associated stigma did not decrease over time. Based on the ethnographic data obtained from 16 months of participant observation in a SARS victims' self-help group and semistructured interviews, I argue that the SARS-associated stigma was maintained, revived, and reconstructed by the biomedical encounters, government institutions, and public perception. I also provide new insight on how the SARS-associated stigma could create problems for public health development in Hong Kong. As communicable diseases will be a continuing threat for the human society, understanding how the disease-associated stigma affects the outcomes of epidemic control measures will be crucial in developing a more responsive public health policy as well as medical follow-up and social support service to the diseased social groups of future epidemic outbreaks. PMID:18503014

  16. Advanced digital SAR processing study

    NASA Technical Reports Server (NTRS)

    Martinson, L. W.; Gaffney, B. P.; Liu, B.; Perry, R. P.; Ruvin, A.

    1982-01-01

    A highly programmable, land based, real time synthetic aperture radar (SAR) processor requiring a processed pixel rate of 2.75 MHz or more in a four look system was designed. Variations in range and azimuth compression, number of looks, range swath, range migration and SR mode were specified. Alternative range and azimuth processing algorithms were examined in conjunction with projected integrated circuit, digital architecture, and software technologies. The advaced digital SAR processor (ADSP) employs an FFT convolver algorithm for both range and azimuth processing in a parallel architecture configuration. Algorithm performace comparisons, design system design, implementation tradeoffs and the results of a supporting survey of integrated circuit and digital architecture technologies are reported. Cost tradeoffs and projections with alternate implementation plans are presented.

  17. Applying PolSAR and PolInSAR to Forest Structure Information Extraction

    NASA Astrophysics Data System (ADS)

    Chen, E.; Li, Z.; Li, W.; Feng, Q.; Zhou, W.; Pottier, E.; Hong, W.

    2013-01-01

    The key research activities and achievements in the field of applying PolSAR and PolInSAR to forest structure information extraction in DRAGON 2 are summarized in this paper. The limitation of the ALOS PolInSAR dataset acquired in the Culai test site for forest height extraction because of its long temporal baseline (46 days), and how the PolInSAR coherence optimization methods can help improve the topography inversion accuracy under forest canopy were presented. We have analyzed and evaluated the capability of multiple polarization parameters extracted from different frequency PolSAR data for forest scar mapping in the Shibazhan test site, and developed the land cover classification method based on SVM (Support Vector Machine) using PolSAR data. With the L-band E-SAR PolInSAR data acquired in the test site in Germany, we developed forest above ground biomass (AGB) estimation approach based on polarization coherence tomography (PCT).

  18. 5. SWITCH TOWER AND JUNCTION OF S.A.R. #1 & S.A.R. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. SWITCH TOWER AND JUNCTION OF S.A.R. #1 & S.A.R. #2 TRANSMISSION LINES, MARCH 7, 1916. SCE drawing no. 4932. - Santa Ana River Hydroelectric System, Transmission Lines, Redlands, San Bernardino County, CA

  19. SAR Image Complex Pixel Representations

    SciTech Connect

    Doerry, Armin W.

    2015-03-01

    Complex pixel values for Synthetic Aperture Radar (SAR) images of uniform distributed clutter can be represented as either real/imaginary (also known as I/Q) values, or as Magnitude/Phase values. Generally, these component values are integers with limited number of bits. For clutter energy well below full-scale, Magnitude/Phase offers lower quantization noise than I/Q representation. Further improvement can be had with companding of the Magnitude value.

  20. Reflectors for SAR performance testing.

    SciTech Connect

    Doerry, Armin Walter

    2008-01-01

    Synthetic Aperture Radar (SAR) performance testing and estimation is facilitated by observing the system response to known target scene elements. Trihedral corner reflectors and other canonical targets play an important role because their Radar Cross Section (RCS) can be calculated analytically. However, reflector orientation and the proximity of the ground and mounting structures can significantly impact the accuracy and precision with which measurements can be made. These issues are examined in this report.

  1. Representing SAR complex image pixels

    NASA Astrophysics Data System (ADS)

    Doerry, A. W.

    2016-05-01

    Synthetic Aperture Radar (SAR) images are often complex-valued to facilitate specific exploitation modes. Furthermore, these pixel values are typically represented with either real/imaginary (also known as I/Q) values, or as Magnitude/Phase values, with constituent components comprised of integers with limited number of bits. For clutter energy well below full-scale, Magnitude/Phase offers lower quantization noise than I/Q representation. Further improvement can be had with companding of the Magnitude value.

  2. Spaceborne SAR Imaging Algorithm for Coherence Optimized

    PubMed Central

    Qiu, Zhiwei; Yue, Jianping; Wang, Xueqin; Yue, Shun

    2016-01-01

    This paper proposes SAR imaging algorithm with largest coherence based on the existing SAR imaging algorithm. The basic idea of SAR imaging algorithm in imaging processing is that output signal can have maximum signal-to-noise ratio (SNR) by using the optimal imaging parameters. Traditional imaging algorithm can acquire the best focusing effect, but would bring the decoherence phenomenon in subsequent interference process. Algorithm proposed in this paper is that SAR echo adopts consistent imaging parameters in focusing processing. Although the SNR of the output signal is reduced slightly, their coherence is ensured greatly, and finally the interferogram with high quality is obtained. In this paper, two scenes of Envisat ASAR data in Zhangbei are employed to conduct experiment for this algorithm. Compared with the interferogram from the traditional algorithm, the results show that this algorithm is more suitable for SAR interferometry (InSAR) research and application. PMID:26871446

  3. Monitoring of Three Case Studies of Creeping Landslides in Ecuador using L-band SAR Interferometry (InSAR)

    NASA Astrophysics Data System (ADS)

    Mayorga Torres, T. M.; Mohseni Aref, M.

    2015-12-01

    Tannia Mayorga Torres1,21 Universidad Central del Ecuador. Faculty of Geology, Mining, Oil, and Environment 2 Hubert H. Humphrey Fellowship 2015-16 IntroductionLandslides lead to human and economic losses across the country, mainly in the winter season. On the other hand, satellite radar data has cost-effective benefits due to open-source software and free availability of data. With the purpose of establishing an early warning system of landslide-related surface deformation, three case studies were designed in the Coast, Sierra (Andean), and Oriente (jungle) regions. The objective of this work was to assess the capability of L-band InSAR to get phase information. For the calculation of the interferograms in Repeat Orbit Interferometry PACkage, the displacement was detected as the error and was corrected. The coherence images (Figure 1) determined that L-band is suitable for InSAR processing. Under this frame, as a first approach, the stacking DInSAR technique [1] was applied in the case studies [2]; however, due to lush vegetation and steep topography, it is necessary to apply advanced InSAR techniques [3]. The purpose of the research is to determine a pattern of data acquisition and successful results to understand the spatial and temporal ground movements associated with landslides. The further work consists of establishing landslide inventories to combine phases of SAR images to generate maps of surface deformation in Tumba-San Francisco and Guarumales to compare the results with ground-based measurements to determine the maps' accuracy. References[1] Sandwell D., Price E. (1998). Phase gradient approach to stacking interferograms. Journal of Geophysical Research, Vol. 103, N. B12, pp. 30,183-30,204. [2] Mayorga T., Platzeck G. (2014). Using DInSAR as a tool to detect unstable terrain areas in an Andes region in Ecuador. NH3.5-Blue Poster B298, Vol. 16, EGU2014-16203. Austria. [3] Wasowski J., Bovenga F. (2014). Investigating landslides and unstable slopes with

  4. Building detection in SAR imagery

    SciTech Connect

    Steinbach, Ryan Matthew

    2015-04-01

    Current techniques for building detection in Synthetic Aperture Radar (SAR) imagery can be computationally expensive and/or enforce stringent requirements for data acquisition. I present two techniques that are effective and efficient at determining an approximate building location. This approximate location can be used to extract a portion of the SAR image to then perform a more robust detection. The proposed techniques assume that for the desired image, bright lines and shadows, SAR artifact effects, are approximately labeled. These labels are enhanced and utilized to locate buildings, only if the related bright lines and shadows can be grouped. In order to find which of the bright lines and shadows are related, all of the bright lines are connected to all of the shadows. This allows the problem to be solved from a connected graph viewpoint, where the nodes are the bright lines and shadows and the arcs are the connections between bright lines and shadows. For the first technique, constraints based on angle of depression and the relationship between connected bright lines and shadows are applied to remove unrelated arcs. The second technique calculates weights for the connections and then performs a series of increasingly relaxed hard and soft thresholds. This results in groups of various levels on their validity. Once the related bright lines and shadows are grouped, their locations are combined to provide an approximate building location. Experimental results demonstrate the outcome of the two techniques. The two techniques are compared and discussed.

  5. Multiresolution FOPEN SAR image formation

    NASA Astrophysics Data System (ADS)

    DiPietro, Robert C.; Fante, Ronald L.; Perry, Richard P.; Soumekh, Mehrdad; Tromp, Laurens D.

    1999-08-01

    This paper presents a new technique for FOPEN SAR (foliage penetration synthetic aperture radar) image formation of Ultra Wideband UHF radar data. Planar Subarray Processing (PSAP) has successfully demonstrated the capability of forming multi- resolution images for X and Ka band radar systems under MITRE IR&D and the DARPA IBC program. We have extended the PSAP algorithm to provide the capability to form strip map, multi- resolution images for Ultra Wideband UHF radar systems. The PSAP processing can accommodate very large SAR integration angles and the resulting very large range migration. It can also accommodate long coherent integration times and wide swath coverage. Major PSAP algorithm features include: multiple SAR sub-arrays providing different look angles at the same image area that can enable man-made target responses to be distinguished from other targets and clutter by their angle dependent specular characteristics, the capability to provide a full resolution image in these and other selected areas without the processing penalty of full resolution in non required areas, and the capability to include angle-dependent motion compensation within the image formation process.

  6. InSAR Forensics: Tracing InSAR Scatterers in High Resolution Optical Image

    NASA Astrophysics Data System (ADS)

    Wang, Yuanyuan; Zhu, XiaoXiang

    2015-05-01

    This paper presents a step towards a better interpretation of the scattering mechanism of different objects and their deformation histories in SAR interferometry (InSAR). The proposed technique traces individual SAR scatterer in high resolution optical images where their geometries, materials, and other properties can be better analyzed and classified. And hence scatterers of a same object can be analyzed in group, which brings us to a new level of InSAR deformation monitoring.

  7. Chirp Scaling Algorithms for SAR Processing

    NASA Technical Reports Server (NTRS)

    Jin, M.; Cheng, T.; Chen, M.

    1993-01-01

    The chirp scaling SAR processing algorithm is both accurate and efficient. Successful implementation requires proper selection of the interval of output samples, which is a function of the chirp interval, signal sampling rate, and signal bandwidth. Analysis indicates that for both airborne and spaceborne SAR applications in the slant range domain a linear chirp scaling is sufficient. To perform nonlinear interpolation process such as to output ground range SAR images, one can use a nonlinear chirp scaling interpolator presented in this paper.

  8. A Modular and Configurable Instrument Electronics Architecture for "MiniSAR"- An Advanced Smallsat SAR Instrument

    NASA Astrophysics Data System (ADS)

    Gomez, Jaime; Pastena, Max; Bierens, Laurens

    2013-08-01

    MiniSAR is a Dutch program focused on the development of a commercial smallsat featuring a SAR instrument, led by SSBV as prime contractor. In this paper an Instrument Electronics (IEL) system concept to meet the MiniSAR demands is presented. This system has several specificities wrt similar initiatives in the European space industry, driven by our main requirement: keep it small.

  9. High resolution SAR applications and instrument design

    NASA Technical Reports Server (NTRS)

    Dionisio, C.; Torre, A.

    1993-01-01

    The Synthetic Aperture Radar (SAR) has viewed, in the last two years, a huge increment of interest from many preset and potential users. The good spatial resolution associated to the all weather capability lead to considering SAR not only a scientific instrument but a tool for verifying and controlling the daily human relationships with the Earth Environment. New missions were identified for SAR as spatial resolution became lower than three meters: disasters, pollution, ships traffic, volcanic eruptions, earthquake effect are only a few of the possible objects which can be effectively detected, controlled and monitored by SAR mounted on satellites. High resolution radar design constraints and dimensioning are discussed.

  10. Bistatic SAR: Signal Processing and Image Formation.

    SciTech Connect

    Wahl, Daniel E.; Yocky, David A.

    2014-10-01

    This report describes the significant processing steps that were used to take the raw recorded digitized signals from the bistatic synthetic aperture RADAR (SAR) hardware built for the NCNS Bistatic SAR project to a final bistatic SAR image. In general, the process steps herein are applicable to bistatic SAR signals that include the direct-path signal and the reflected signal. The steps include preprocessing steps, data extraction to for a phase history, and finally, image format. Various plots and values will be shown at most steps to illustrate the processing for a bistatic COSMO SkyMed collection gathered on June 10, 2013 on Kirtland Air Force Base, New Mexico.

  11. Three-dimensional surface reconstruction from multistatic SAR images.

    PubMed

    Rigling, Brian D; Moses, Randolph L

    2005-08-01

    This paper discusses reconstruction of three-dimensional surfaces from multiple bistatic synthetic aperture radar (SAR) images. Techniques for surface reconstruction from multiple monostatic SAR images already exist, including interferometric processing and stereo SAR. We generalize these methods to obtain algorithms for bistatic interferometric SAR and bistatic stereo SAR. We also propose a framework for predicting the performance of our multistatic stereo SAR algorithm, and, from this framework, we suggest a metric for use in planning strategic deployment of multistatic assets. PMID:16121463

  12. InfoTerra/TerraSAR initiative

    NASA Astrophysics Data System (ADS)

    Wahl, Manfred W.

    2004-01-01

    The overarching goal of the InfoTerra/TerraSAR Initiative is to establish a self-sustaining operational/commercial business built on Europe"s know-how and experience in space-borne Synthetic Aperture Radar (SAR) technology, in SAR data processing as well as in SAR applications. InfoTerra stands for a new business concept based on supplying innovative geo-information products and services. TerraSAR is a space and ground system conceived to consist of an initial deployment and operation of 2 Radar satellites (one in X- and one in L-band) flying in a tandem configuration in the same orbit. The design of TerraSAR is driven by the market and is user-oriented. TerraSAR is key to capturing a significant proportion of the existing market and to opening new market opportunities, when it becomes operational. The InfoTerra/TerraSAR Initiative has evolved gradually. It started in 1997 as a joint venture between German (DSS) and British (MMS-UK) space industry, strongly supported by both space agencies, DLR and BNSC. In early 2001, DLR and BNSC submitted to ESA the Formal Programme Proposal for InfoTerra/TerraSAR to become an essential element of ESA"s Earth Watch Programme. In summer 2001, when it became evident that there was not yet sufficient support from the ESA Member States to allow immediate start entering into TerraSAR Phase C/D, it has been decided to implement first a TerraSAR consolidation phase. In early 2002, in order to avoid further delays, a contract was signed between DLR and Astrium GmbH on the development of one component of TerraSAR, the TerraSAR-X, in the frame of a national programme, governed by a Public Private Partnership Agreement. Even if now the different launch dates for TerraSAR-X and TerraSAR-L are narrowing down the window of common data acquisition, it is a reasonable starting point, but it should always be kept in mind that the utmost goal for the longterm is to achieve self sustainability by supplying geo-information products and services

  13. Detection of airborne severe acute respiratory syndrome (SARS) coronavirus and environmental contamination in SARS outbreak units.

    PubMed

    Booth, Timothy F; Kournikakis, Bill; Bastien, Nathalie; Ho, Jim; Kobasa, Darwyn; Stadnyk, Laurie; Li, Yan; Spence, Mel; Paton, Shirley; Henry, Bonnie; Mederski, Barbara; White, Diane; Low, Donald E; McGeer, Allison; Simor, Andrew; Vearncombe, Mary; Downey, James; Jamieson, Frances B; Tang, Patrick; Plummer, Frank

    2005-05-01

    Severe acute respiratory syndrome (SARS) is characterized by a risk of nosocomial transmission; however, the risk of airborne transmission of SARS is unknown. During the Toronto outbreaks of SARS, we investigated environmental contamination in SARS units, by employing novel air sampling and conventional surface swabbing. Two polymerase chain reaction (PCR)-positive air samples were obtained from a room occupied by a patient with SARS, indicating the presence of the virus in the air of the room. In addition, several PCR-positive swab samples were recovered from frequently touched surfaces in rooms occupied by patients with SARS (a bed table and a television remote control) and in a nurses' station used by staff (a medication refrigerator door). These data provide the first experimental confirmation of viral aerosol generation by a patient with SARS, indicating the possibility of airborne droplet transmission, which emphasizes the need for adequate respiratory protection, as well as for strict surface hygiene practices. PMID:15809906

  14. Sentinel-3 SAR Altimetry Toolbox

    NASA Astrophysics Data System (ADS)

    Benveniste, Jerome; Lucas, Bruno; DInardo, Salvatore

    2015-04-01

    The prime objective of the SEOM (Scientific Exploitation of Operational Missions) element is to federate, support and expand the large international research community that the ERS, ENVISAT and the Envelope programmes have build up over the last 20 years for the future European operational Earth Observation missions, the Sentinels. Sentinel-3 builds directly on a proven heritage of ERS-2 and Envisat, and CryoSat-2, with a dual-frequency (Ku and C band) advanced Synthetic Aperture Radar Altimeter (SRAL) that provides measurements at a resolution of ~300m in SAR mode along track. Sentinel-3 will provide exact measurements of sea-surface height along with accurate topography measurements over sea ice, ice sheets, rivers and lakes. The first of the two Sentinels is expected to be launched in early 2015. The current universal altimetry toolbox is BRAT (Basic Radar Altimetry Toolbox) which can read all previous and current altimetry mission's data, but it does not have the capabilities to read the upcoming Sentinel-3 L1 and L2 products. ESA will endeavour to develop and supply this capability to support the users of the future Sentinel-3 SAR Altimetry Mission. BRAT is a collection of tools and tutorial documents designed to facilitate the processing of radar altimetry data. This project started in 2005 from the joint efforts of ESA (European Space Agency) and CNES (Centre National d'Etudes Spatiales), and it is freely available at http://earth.esa.int/brat. The tools enable users to interact with the most common altimetry data formats, the BratGUI is the front-end for the powerful command line tools that are part of the BRAT suite. BRAT can also be used in conjunction with Matlab/IDL (via reading routines) or in C/C++/Fortran via a programming API, allowing the user to obtain desired data, bypassing the data-formatting hassle. BRAT can be used simply to visualise data quickly, or to translate the data into other formats such as netCDF, ASCII text files, KML (Google Earth

  15. Cross-calibration between airborne SAR sensors

    NASA Technical Reports Server (NTRS)

    Zink, Manfred; Olivier, Philippe; Freeman, Anthony

    1993-01-01

    As Synthetic Aperture Radar (SAR) system performance and experience in SAR signature evaluation increase, quantitative analysis becomes more and more important. Such analyses require an absolute radiometric calibration of the complete SAR system. To keep the expenditure on calibration of future multichannel and multisensor remote sensing systems (e.g., X-SAR/SIR-C) within a tolerable level, data from different tracks and different sensors (channels) must be cross calibrated. The 1989 joint E-SAR/DC-8 SAR calibration campaign gave a first opportunity for such an experiment, including cross sensor and cross track calibration. A basic requirement for successful cross calibration is the stability of the SAR systems. The calibration parameters derived from different tracks and the polarimetric properties of the uncalibrated data are used to describe this stability. Quality criteria for a successful cross calibration are the agreement of alpha degree values and the consistency of radar cross sections of equally sized corner reflectors. Channel imbalance and cross talk provide additional quality in case of the polarimetric DC-8 SAR.

  16. A Simple Model for a SARS Epidemic

    ERIC Educational Resources Information Center

    Ang, Keng Cheng

    2004-01-01

    In this paper, we examine the use of an ordinary differential equation in modelling the SARS outbreak in Singapore. The model provides an excellent example of using mathematics in a real life situation. The mathematical concepts involved are accessible to students with A level Mathematics backgrounds. Data for the SARS epidemic in Singapore are…

  17. Knowledge based SAR images exploitations

    NASA Astrophysics Data System (ADS)

    Wang, David L.

    1987-01-01

    One of the basic functions of SAR images exploitation system is the detection of man-made objects. The performance of object detection is strongly limited by performance of segmentation modules. This paper presents a detection paradigm composed of an adaptive segmentation algorithm based on a priori knowledge of objects followed by a top-down hierarchical detection process that generates and evaluates object hypotheses. Shadow information and inter-object relationships can be added to the knowledge base to improve performance over that of a statistical detector based only on the attributes of individual objects.

  18. Regularization Analysis of SAR Superresolution

    SciTech Connect

    DELAURENTIS,JOHN M.; DICKEY,FRED M.

    2002-04-01

    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. In a previous report the application of the concept to synthetic aperture radar was investigated as an operator inversion problem. Generally, the operator inversion problem is ill posed. This work treats the problem from the standpoint of regularization. Both the operator inversion approach and the regularization approach show that the ability to superresolve SAR imagery is severely limited by system noise.

  19. Making Mosaics Of SAR Imagery

    NASA Technical Reports Server (NTRS)

    Curlander, John C.; Kwok, Ronald; Pang, Shirley S.; Pang, Amy A.

    1990-01-01

    Spaceborne synthetic-aperture-radar (SAR) images useful for mapping of planets and investigations in Earth sciences. Produces multiframe mosaic by combining images along ground track, in adjacent cross-track swaths, or in ascending and descending passes. Images registered with geocoded maps such as ones produced by MAPJTC (NPO-17718), required as input. Minimal intervention by operator required. MOSK implemented on DEC VAX 11/785 computer running VMS 4.5. Most subroutines in FORTRAN, but three in MAXL and one in APAL.

  20. Reconnaissance with slant plane circular SAR imaging.

    PubMed

    Soumekh, M

    1996-01-01

    This paper presents a method for imaging from the slant plane data collected by a synthetic aperture radar (SAR) over the full rotation or a partial segment of a circular flight path. A Fourier analysis for the Green's function of the imaging system is provided. This analysis is the basis of an inversion for slant plane circular SAR data. The reconstruction algorithm and resolution for this SAR system are outlined. It is shown that the slant plane circular SAR, unlike the slant plane linear SAR, has the capability to extract three-dimensional imaging information of a target scene. The merits of the algorithm are demonstrated via a simulated target whose ultra wideband foliage penetrating (FOPEN) or ground penetrating (GPEN) ultrahigh frequency (UHF) radar signature varies with the radar's aspect angle. PMID:18285213

  1. SARS and Population Health Technology

    PubMed Central

    2003-01-01

    The recent global outbreak of SARS (severe acute respiratory syndrome) provides an opportunity to study the use and impact of public health informatics and population health technology to detect and fight a global epidemic. Population health technology is the umbrella term for technology applications that have a population focus and the potential to improve public health. This includes the Internet, but also other technologies such as wireless devices, mobile phones, smart appliances, or smart homes. In the context of an outbreak or bioterrorism attack, such technologies may help to gather intelligence and detect diseases early, and communicate and exchange information electronically worldwide. Some of the technologies brought forward during the SARS epidemic may have been primarily motivated by marketing efforts, or were more directed towards reassuring people that "something is being done," ie, fighting an "epidemic of fear." To understand "fear epidemiology" is important because early warning systems monitoring data from a large number of people may not be able to discriminate between a biological epidemic and an epidemic of fear. The need for critical evaluation of all of these technologies is stressed. PMID:12857670

  2. History of SAR at Lockheed Martin (previously Goodyear Aerospace)

    NASA Astrophysics Data System (ADS)

    Lasswell, Stephen W.

    2005-05-01

    Synthetic Aperture Radar (SAR) was invented by Carl Wiley at Goodyear Aircraft Company in Goodyear, Arizona, in 1951. From that time forward, as the company became Goodyear Aerospace Corporation, Loral Corporation, and finally Lockheed Martin Corporation, the Arizona employees past and present played a long and storied role in numerous SAR firsts. These include the original SAR patent (known as Simultaneous Doppler Buildup), the first demonstration SAR and flight test, the first operational SAR system, the first operational SAR data link, the first 5-foot resolution operational SAR system, the first 1-foot resolution SAR system, and the first large scale SAR digital processor. The company has installed and flown over five hundred SAR systems on more than thirty different types of aircraft for numerous countries throughout the world. The company designed and produced all of the evolving high performance SAR systems for the U. S. Air Force SR-71 "Blackbird" spy plane throughout its entire operational history, spanning some twenty-nine years. Recent SAR accomplishments include long-range standoff high performance SAR systems, smaller high resolution podded SAR systems for fighter aircraft, and foliage penetration (FOPEN) SAR. The company is currently developing the high performance SAR/MTI (Moving Target Indication) radar for the Army Aerial Common Sensor (ACS) system.

  3. SAR image formation toolbox for MATLAB

    NASA Astrophysics Data System (ADS)

    Gorham, LeRoy A.; Moore, Linda J.

    2010-04-01

    While many synthetic aperture radar (SAR) image formation techniques exist, two of the most intuitive methods for implementation by SAR novices are the matched filter and backprojection algorithms. The matched filter and (non-optimized) backprojection algorithms are undeniably computationally complex. However, the backprojection algorithm may be successfully employed for many SAR research endeavors not involving considerably large data sets and not requiring time-critical image formation. Execution of both image reconstruction algorithms in MATLAB is explicitly addressed. In particular, a manipulation of the backprojection imaging equations is supplied to show how common MATLAB functions, ifft and interp1, may be used for straight-forward SAR image formation. In addition, limits for scene size and pixel spacing are derived to aid in the selection of an appropriate imaging grid to avoid aliasing. Example SAR images generated though use of the backprojection algorithm are provided given four publicly available SAR datasets. Finally, MATLAB code for SAR image reconstruction using the matched filter and backprojection algorithms is provided.

  4. The Alaska SAR processor - Operations and control

    NASA Technical Reports Server (NTRS)

    Carande, Richard E.

    1989-01-01

    The Alaska SAR (synthetic-aperture radar) Facility (ASF) will be capable of receiving, processing, archiving, and producing a variety of SAR image products from three satellite-borne SARs: E-ERS-1 (ESA), J-ERS-1 (NASDA) and Radarsat (Canada). Crucial to the success of the ASF is the Alaska SAR processor (ASP), which will be capable of processing over 200 100-km x 100-km (Seasat-like) frames per day from the raw SAR data, at a ground resolution of about 30 m x 30 m. The processed imagery is of high geometric and radiometric accuracy, and is geolocated to within 500 m. Special-purpose hardware has been designed to execute a SAR processing algorithm to achieve this performance. This hardware is currently undergoing acceptance testing for delivery to the University of Alaska. Particular attention has been devoted to making the operations semi-automated and to providing a friendly operator interface via a computer workstation. The operations and control of the Alaska SAR processor are described.

  5. SAR and LIDAR fusion: experiments and applications

    NASA Astrophysics Data System (ADS)

    Edwards, Matthew C.; Zaugg, Evan C.; Bradley, Joshua P.; Bowden, Ryan D.

    2013-05-01

    In recent years ARTEMIS, Inc. has developed a series of compact, versatile Synthetic Aperture Radar (SAR) systems which have been operated on a variety of small manned and unmanned aircraft. The multi-frequency-band SlimSAR has demonstrated a variety of capabilities including maritime and littoral target detection, ground moving target indication, polarimetry, interferometry, change detection, and foliage penetration. ARTEMIS also continues to build upon the radar's capabilities through fusion with other sensors, such as electro-optical and infrared camera gimbals and light detection and ranging (LIDAR) devices. In this paper we focus on experiments and applications employing SAR and LIDAR fusion. LIDAR is similar to radar in that it transmits a signal which, after being reflected or scattered by a target area, is recorded by the sensor. The differences are that a LIDAR uses a laser as a transmitter and optical sensors as a receiver, and the wavelengths used exhibit a very different scattering phenomenology than the microwaves used in radar, making SAR and LIDAR good complementary technologies. LIDAR is used in many applications including agriculture, archeology, geo-science, and surveying. Some typical data products include digital elevation maps of a target area and features and shapes extracted from the data. A set of experiments conducted to demonstrate the fusion of SAR and LIDAR data include a LIDAR DEM used in accurately processing the SAR data of a high relief area (mountainous, urban). Also, feature extraction is used in improving geolocation accuracy of the SAR and LIDAR data.

  6. Next generation SAR demonstration on space station

    SciTech Connect

    Edelstein, Wendy; Kim, Yunjin; Freeman, Anthony; Jordan, Rolando

    1999-01-22

    This paper describes the next generation synthetic aperture radar (SAR) that enables future low cost space-borne radar missions. In order to realize these missions, we propose to use an inflatable, membrane, microstrip antenna that is particularly suitable for low frequency science radar missions. In order to mitigate risks associated with this revolutionary technology, the space station demonstration will be very useful to test the long-term survivability of the proposed antenna. This experiment will demonstrate several critical technology challenges associated with space-inflatable technologies. Among these include space-rigidization of inflatable structures, controlled inflation deployment, flatness and uniform separation of thin-film membranes and RF performance of membrane microstrip antennas. This mission will also verify the in-space performance of lightweight, high performance advanced SAR electronics. Characteristics of this SAR instrument include a capability for high resolution polarimetric imaging. The mission will acquire high quality scientific data using this advanced SAR to demonstrate the utility of these advanced technologies. We will present an inflatable L-band SAR concept for commercial and science applications and a P-band design concept to validate the Biomass SAR mission concept. The ionospheric effects on P-band SAR images will also be examined using the acquired data.

  7. First Results from an Airborne Ka-band SAR Using SweepSAR and Digital Beamforming

    NASA Technical Reports Server (NTRS)

    Sadowy, Gregory; Ghaemi, Hirad; Hensley, Scott

    2012-01-01

    NASA/JPL has developed SweepSAR technique that breaks typical Synthetic Aperture Radar (SAR) trade space using time-dependent multi-beam DBF on receive. Developing SweepSAR implementation using array-fed reflector for proposed DESDynI Earth Radar Mission concept. Performed first-of-a-kind airborne demonstration of the SweepSAR concept at Ka-band (35.6 GHz). Validated calibration and antenna pattern data sufficient for beam forming in elevation. (1) Provides validation evidence that the proposed Deformation Ecosystem Structure Dynamics of Ice (DESDynI) SAR architecture is sound. (2) Functions well even with large variations in receiver gain / phase. Future plans include using prototype DESDynI SAR digital flight hardware to do the beam forming in real-time onboard the aircraft.

  8. Geometric accuracy in airborne SAR images

    NASA Technical Reports Server (NTRS)

    Blacknell, D.; Quegan, S.; Ward, I. A.; Freeman, A.; Finley, I. P.

    1989-01-01

    Uncorrected across-track motions of a synthetic aperture radar (SAR) platform can cause both a severe loss of azimuthal positioning accuracy in, and defocusing of, the resultant SAR image. It is shown how the results of an autofocus procedure can be incorporated in the azimuth processing to produce a fully focused image that is geometrically accurate in azimuth. Range positioning accuracy is also discussed, leading to a comprehensive treatment of all aspects of geometric accuracy. The system considered is an X-band SAR.

  9. Design considerations of GeoSAR

    NASA Astrophysics Data System (ADS)

    Kim, Yunjin; Hensley, Scott; Veilleux, Louise; Edelstein, W.; Lou, Yun-Ling; Burken, A.; Skotnicky, W. F.; Sato, T.; Brown, W.

    1996-06-01

    The primary purpose of GeoSAR is to demonstrate the feasibility of interferometric topographic mapping through foliage penetration. GeoSAR should become a commercially viable instrument after the feasibility demonstration. To satisfy both requirements, we have designed a dual frequency (UHF- and X-band) interferometric radar. For foliage penetration, a lower frequency (UHF) radar is used. To obtain better height accuracy for low backscatter areas, we proposed a high frequency (X-band) interferometric system. In this paper, we present a possible GeoSAR system configuration and associated performance estimation.

  10. Primary studies of Chinese spaceborne SAR

    NASA Technical Reports Server (NTRS)

    Wang, Zhen-Song; Wu, Guo-Xiang; Guo, Hua-Dong; Wei, Zhong-Quan; Zhu, Min-Hui

    1993-01-01

    The primary studies on spaceborne synthetic aperture radar (SAR) in China are discussed. The SAR will be launched aboard a Chinese satellite and operated at L-band with HH polarization. The purpose of the mission in consideration is dedicated to resources and environment uses, especially to natural disaster monitoring. The ground resolution is designed as 25 m x 25 m for detailed mode and 100 m x 100 m for wide scan-SAR mode. The off-nadir angle can be varied from 20 to 40 deg. The key system concepts are introduced.

  11. NASA/JPL Aircraft SAR Workshop Proceedings

    NASA Technical Reports Server (NTRS)

    Donovan, N. (Editor); Evans, D. L. (Editor); Held, D. N. (Editor)

    1985-01-01

    Speaker-supplied summaries of the talks given at the NASA/JPL Aircraft SAR Workshop on February 4 and 5, 1985, are provided. These talks dealt mostly with composite quadpolarization imagery from a geologic or ecologic prespective. An overview and summary of the system characteristics of the L-band synthetic aperture radar (SAR) flown on the NASA CV-990 aircraft are included as supplementary information. Other topics ranging from phase imagery and interferometric techniques classifications of specific areas, and the potentials and limitations of SAR imagery in various applications are discussed.

  12. Segmentation Of Multifrequency, Multilook SAR Data

    NASA Technical Reports Server (NTRS)

    Rignot, Eric J.; Kwok, Ronald; Chellappa, Rama

    1993-01-01

    Segmentation of multifrequency, multilook synthetic-aperture radar (SAR) image intensity data into regions, within each of which backscattering characteristics of target scene considered homogeneous, enhanced by use of two statistical models. One represents statistics of multifrequency, multilook speckled intensities of SAR picture elements; other represents statistics of labels applied to regions into which picture elements grouped. Each region represents different type of terrain, terrain cover, or other surface; e.g., forest, agricultural land, sea ice, or water. Segmentation of image into regions of neighboring picture elements accomplished by method similar to that described in "Algorithms For Segmentation Of Complex-Amplitude SAR Data" (NPO-18524).

  13. Similarity measures of full polarimetric SAR images fusion for improved SAR image matching

    NASA Astrophysics Data System (ADS)

    Ding, H.

    2015-06-01

    China's first airborne SAR mapping system (CASMSAR) developed by Chinese Academy of Surveying and Mapping can acquire high-resolution and full polarimetric (HH, HV, VH and VV) Synthetic aperture radar (SAR) data. It has the ability to acquire X-band full polarimetric SAR data at a resolution of 0.5m. However, the existence of speckles which is inherent in SAR imagery affects visual interpretation and image processing badly, and challenges the assumption that conjugate points appear similar to each other in matching processing. In addition, researches show that speckles are multiplicative speckles, and most similarity measures of SAR image matching are sensitive to them. Thus, matching outcomes of SAR images acquired by most similarity measures are not reliable and with bad accuracy. Meanwhile, every polarimetric SAR image has different backscattering information of objects from each other and four polarimetric SAR data contain most basic and a large amount of redundancy information to improve matching. Therefore, we introduced logarithmically transformation and a stereo matching similarity measure into airborne full polarimetric SAR imagery. Firstly, in order to transform the multiplicative speckles into additivity ones and weaken speckles' influence on similarity measure, logarithmically transformation have to be taken to all images. Secondly, to prevent performance degradation of similarity measure caused by speckles, measure must be free or insensitive of additivity speckles. Thus, we introduced a stereo matching similarity measure, called Normalized Cross-Correlation (NCC), into full polarimetric SAR image matching. Thirdly, to take advantage of multi-polarimetric data and preserve the best similarity measure value, four measure values calculated between left and right single polarimetric SAR images are fused as final measure value for matching. The method was tested for matching under CASMSAR data. The results showed that the method delivered an effective

  14. SEASAT SAR performance evaluation study

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The performance of the SEASAT synthetic aperture radar (SAR) sensor was evaluated using data processed by the MDA digital processor. Two particular aspects are considered the location accuracy of image data, and the calibration of the measured backscatter amplitude of a set of corner reflectors. The image location accuracy was assessed by selecting identifiable targets in several scenes, converting their image location to UTM coordinates, and comparing the results to map sheets. The error standard deviation is measured to be approximately 30 meters. The amplitude was calibrated by measuring the responses of the Goldstone corner reflector array and comparing the results to theoretical values. A linear regression of the measured against theoretical values results in a slope of 0.954 with a correlation coefficient of 0.970.

  15. Combined DEM Extration Method from StereoSAR and InSAR

    NASA Astrophysics Data System (ADS)

    Zhao, Z.; Zhang, J. X.; Duan, M. Y.; Huang, G. M.; Yang, S. C.

    2015-06-01

    A pair of SAR images acquired from different positions can be used to generate digital elevation model (DEM). Two techniques exploiting this characteristic have been introduced: stereo SAR and interferometric SAR. They permit to recover the third dimension (topography) and, at the same time, to identify the absolute position (geolocation) of pixels included in the imaged area, thus allowing the generation of DEMs. In this paper, StereoSAR and InSAR combined adjustment model are constructed, and unify DEM extraction from InSAR and StereoSAR into the same coordinate system, and then improve three dimensional positioning accuracy of the target. We assume that there are four images 1, 2, 3 and 4. One pair of SAR images 1,2 meet the required conditions for InSAR technology, while the other pair of SAR images 3,4 can form stereo image pairs. The phase model is based on InSAR rigorous imaging geometric model. The master image 1 and the slave image 2 will be used in InSAR processing, but the slave image 2 is only used in the course of establishment, and the pixels of the slave image 2 are relevant to the corresponding pixels of the master image 1 through image coregistration coefficient, and it calculates the corresponding phase. It doesn't require the slave image in the construction of the phase model. In Range-Doppler (RD) model, the range equation and Doppler equation are a function of target geolocation, while in the phase equation, the phase is also a function of target geolocation. We exploit combined adjustment model to deviation of target geolocation, thus the problem of target solution is changed to solve three unkonwns through seven equations. The model was tested for DEM extraction under spaceborne InSAR and StereoSAR data and compared with InSAR and StereoSAR methods respectively. The results showed that the model delivered a better performance on experimental imagery and can be used for DEM extraction applications.

  16. Statistical Modeling of SAR Images: A Survey

    PubMed Central

    Gao, Gui

    2010-01-01

    Statistical modeling is essential to SAR (Synthetic Aperture Radar) image interpretation. It aims to describe SAR images through statistical methods and reveal the characteristics of these images. Moreover, statistical modeling can provide a technical support for a comprehensive understanding of terrain scattering mechanism, which helps to develop algorithms for effective image interpretation and creditable image simulation. Numerous statistical models have been developed to describe SAR image data, and the purpose of this paper is to categorize and evaluate these models. We first summarize the development history and the current researching state of statistical modeling, then different SAR image models developed from the product model are mainly discussed in detail. Relevant issues are also discussed. Several promising directions for future research are concluded at last. PMID:22315568

  17. An algorithm for segmenting polarimetric SAR imagery

    NASA Astrophysics Data System (ADS)

    Geaga, Jorge V.

    2015-05-01

    We have developed an algorithm for segmenting fully polarimetric single look TerraSAR-X, multilook SIR-C and 7 band Landsat 5 imagery using neural nets. The algorithm uses a feedforward neural net with one hidden layer to segment different surface classes. The weights are refined through an iterative filtering process characteristic of a relaxation process. Features selected from studies of fully polarimetric complex single look TerraSAR-X data and multilook SIR-C data are used as input to the net. The seven bands from Landsat 5 data are used as input for the Landsat neural net. The Cloude-Pottier incoherent decomposition is used to investigate the physical basis of the polarimetric SAR data segmentation. The segmentation of a SIR-C ocean surface scene into four classes is presented. This segmentation algorithm could be a very useful tool for investigating complex polarimetric SAR phenomena.

  18. Polarimetric SAR Interferometry Evaluation in Mangroves

    NASA Technical Reports Server (NTRS)

    Lee, Seung-Kuk; Fatoyinbo,Temilola; Osmanoglu, Batuhan; Sun, Guoqing

    2014-01-01

    TanDEM-X (TDX) enables to generate an interferometric coherence without temporal decorrelation effect that is the most critical factor for a successful Pol-InSAR inversion, as have recently been used for forest parameter retrieval. This paper presents mangrove forest height estimation only using single-pass/single-baseline/dual-polarization TDX data by means of new dual-Pol-InSAR inversion technique. To overcome a lack of one polarization in a conventional Pol- InSAR inversion (i.e. an underdetermined problem), the ground phase in the Pol-InSAR model is directly estimated from TDX interferograms assuming flat underlying topography in mangrove forest. The inversion result is validated against lidar measurement data (NASA's G-LiHT data).

  19. Image based SAR product simulation for analysis

    NASA Technical Reports Server (NTRS)

    Domik, G.; Leberl, F.

    1987-01-01

    SAR product simulation serves to predict SAR image gray values for various flight paths. Input typically consists of a digital elevation model and backscatter curves. A new method is described of product simulation that employs also a real SAR input image for image simulation. This can be denoted as 'image-based simulation'. Different methods to perform this SAR prediction are presented and advantages and disadvantages discussed. Ascending and descending orbit images from NASA's SIR-B experiment were used for verification of the concept: input images from ascending orbits were converted into images from a descending orbit; the results are compared to the available real imagery to verify that the prediction technique produces meaningful image data.

  20. Tracking ocean wave spectrum from SAR images

    NASA Technical Reports Server (NTRS)

    Goldfinger, A. D.; Beal, R. C.; Monaldo, F. M.; Tilley, D. G.

    1984-01-01

    An end to end algorithm for recovery of ocean wave spectral peaks from Synthetic Aperture Radar (SAR) images is described. Current approaches allow precisions of 1 percent in wave number, and 0.6 deg in direction.

  1. SAR/LANDSAT image registration study

    NASA Technical Reports Server (NTRS)

    Murphrey, S. W. (Principal Investigator)

    1978-01-01

    The author has identified the following significant results. Temporal registration of synthetic aperture radar data with LANDSAT-MSS data is both feasible (from a technical standpoint) and useful (from an information-content viewpoint). The greatest difficulty in registering aircraft SAR data to corrected LANDSAT-MSS data is control-point location. The differences in SAR and MSS data impact the selection of features that will serve as a good control points. The SAR and MSS data are unsuitable for automatic computer correlation of digital control-point data. The gray-level data can not be compared by the computer because of the different response characteristics of the MSS and SAR images.

  2. SAR Polarimetry for Oil at Sea Observation

    NASA Astrophysics Data System (ADS)

    Migliaccio, M.; Nunziata, F.

    2013-03-01

    Synthetic aperture radar (SAR) oil slick observation is a topic of great applicative relevance which has been physically recast by a set of new polarimetric approaches that, exploiting the departure from Bragg scattering, allow observing oil at sea in a very robust and effective way. In this study, these polarimetric approaches are reviewed and their performances are discussed with respect to some thought experiments undertaken on quad-pol full-resolution L- and C-band SAR data.

  3. Ionospheric Specifications for SAR Interferometry (ISSI)

    NASA Technical Reports Server (NTRS)

    Pi, Xiaoqing; Chapman, Bruce D; Freeman, Anthony; Szeliga, Walter; Buckley, Sean M.; Rosen, Paul A.; Lavalle, Marco

    2013-01-01

    The ISSI software package is designed to image the ionosphere from space by calibrating and processing polarimetric synthetic aperture radar (PolSAR) data collected from low Earth orbit satellites. Signals transmitted and received by a PolSAR are subject to the Faraday rotation effect as they traverse the magnetized ionosphere. The ISSI algorithms combine the horizontally and vertically polarized (with respect to the radar system) SAR signals to estimate Faraday rotation and ionospheric total electron content (TEC) with spatial resolutions of sub-kilometers to kilometers, and to derive radar system calibration parameters. The ISSI software package has been designed and developed to integrate the algorithms, process PolSAR data, and image as well as visualize the ionospheric measurements. A number of tests have been conducted using ISSI with PolSAR data collected from various latitude regions using the phase array-type L-band synthetic aperture radar (PALSAR) onboard Japan Aerospace Exploration Agency's Advanced Land Observing Satellite mission, and also with Global Positioning System data. These tests have demonstrated and validated SAR-derived ionospheric images and data correction algorithms.

  4. UAVSAR: InSAR and PolSAR Test Bed for the Proposed NI-SAR Mission

    NASA Astrophysics Data System (ADS)

    Jones, C. E.; Hensley, S.; Lou, Y.

    2014-12-01

    UAVSAR, which first became operational in 2009, has served as an operational testbed for the NI-SAR L-band radar concept and a unique instrument in its own right. UAVSAR supports a broad array of basic and applied geoscience, covering on smaller scale all the disciplines NI-SAR would be able to address on a global scale. Although designed specifically to provide high accuracy repeated flight tracks and precise imaging geometry for InSAR-based solid earth studies, its fully polarimetric operation, low noise, and consistent calibration accuracy has made it a premier instrument for PolSAR-based studies also. Since 2009 it has successfully imaged more than 16 million km2 and >4300 quad-polarimetric data products are now publicly available online. Upgrades made in the last year to automate the repeat track processing serve as a model for generating large volumes of InSAR products: Since January 2014 more than 700 interferometric products have been released, exceeding the output of all previous years combined. Standardly available products now include browse images of all InSAR acquisitions and coregistered single-look complex image stacks suitable for standard time series analysis. Here we present an overview of the wide range of studies utilizing UAVSAR data including those based on polarimetry and pair-wise and times series interferometry, highlighting both the unique capabilities of UAVSAR and the ways in which NI-SAR would be able to dramatically extend the capabilities. This research was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  5. Online Health Education on SARS to University Students during the SARS Outbreak

    ERIC Educational Resources Information Center

    Wong, Mee Lian; Koh, David; Iyer, Prasad; Seow, Adeline; Goh, Lee Gan; Chia, Sin Eng; Lim, Meng Kin; Ng, Daniel; Ong, Choon Nam; Phua, Kai Hong; Tambyah, Paul; Chow, Vincent T K; Chew, Suok Kai; Chandran, Ravi; Lee, Hin Peng

    2005-01-01

    Little is known about how online learning may be used to disseminate health information rapidly and widely to large university populations if there is an infectious disease outbreak. During the SARS outbreak in Singapore in 2003, a six-lesson elearning module on SARS was developed for a large university population of 32,000 students. The module…

  6. 23. OVERVIEW OF SAR3 AREA, SHOWING CORNER OF SAR3 WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. OVERVIEW OF SAR-3 AREA, SHOWING CORNER OF SAR-3 WITH TAILRACE, ADMINISTRATIVE OFFICE, TOILET SHED, AND RETAINING WALLS AT FORMER EMPLOYEE HOUSING SITE. VIEW TO SOUTHEAST. PANORAMA 1/2. - Santa Ana River Hydroelectric System, Redlands, San Bernardino County, CA

  7. 20. OVERVIEW OF SAR3 COMPLEX, SHOWING FORMER RESIDENTIAL AREA, SAR3 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. OVERVIEW OF SAR-3 COMPLEX, SHOWING FORMER RESIDENTIAL AREA, SAR-3 SWITCH RACK, MAINTENANCE YARD, AND GREENSPOT BRIDGE. NOTE ALSO LARGE PIPE CONDUCTING TAILRACE WATER INTO IRRIGATION SYSTEM. VIEW TO SOUTHWEST. - Santa Ana River Hydroelectric System, Redlands, San Bernardino County, CA

  8. Investigation of ionospheric effects on SAR Interferometry (InSAR): A case study of Hong Kong

    NASA Astrophysics Data System (ADS)

    Zhu, Wu; Ding, Xiao-Li; Jung, Hyung-Sup; Zhang, Qin; Zhang, Bo-Chen; Qu, Wei

    2016-08-01

    Synthetic Aperture Radar Interferometry (InSAR) has demonstrated its potential for high-density spatial mapping of ground displacement associated with earthquakes, volcanoes, and other geologic processes. However, this technique may be affected by the ionosphere, which can result in the distortions of Synthetic Aperture Radar (SAR) images, phases, and polarization. Moreover, ionospheric effect has become and is becoming further significant with the increasing interest in low-frequency SAR systems, limiting the further development of InSAR technique. Although some research has been carried out, thorough analysis of ionospheric influence on true SAR imagery is still limited. Based on this background, this study performs a thorough investigation of ionospheric effect on InSAR through processing L-band ALOS-1/PALSAR-1 images and dual-frequency Global Positioning System (GPS) data over Hong Kong, where the phenomenon of ionospheric irregularities often occurs. The result shows that the small-scale ionospheric irregularities can cause the azimuth pixel shifts and phase advance errors on interferograms. Meanwhile, it is found that these two effects result in the stripe-shaped features in InSAR images. The direction of the stripe-shaped effects keep approximately constant in space for our InSAR dataset. Moreover, the GPS-derived rate of total electron content change index (ROTI), an index to reflect the level of ionospheric disturbances, may be a useful indicator for predicting the ionospheric effect for SAR images. This finding can help us evaluate the quality of SAR images when considering the ionospheric effect.

  9. A comparative evaluation of SAR and SLAR

    SciTech Connect

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

    1993-11-01

    Synthetic aperture radar (SAR) was evaluated as a potential technological improvement over the Coast Guard`s existing side-looking airborne radar (SLAR) for oil-spill surveillance applications. The US Coast Guard Research and Development Center (R&D Center), Environmental Branch, sponsored a joint experiment including the US Coast Guard, Sandia National Laboratories, and the Naval 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 R&D Center on a computer workstation for analysis by experiment participants. Issues such as optimal spatial resolution, single-look vs. multi-look SAR imaging, and the utility of SAR for oil-spill analysis were addressed. Finally, conceptual design requirements for a possible future Coast Guard SAR were outlined and evaluated.

  10. ICAO's anti-SARS airport activities.

    PubMed

    Finkelstein, Silvio; Curdt-Christiansen, Claus M

    2003-11-01

    To prevent SARS from spreading through air travel and in order to rebuild the confidence of the traveling public in the safety of air travel, ICAO has set up an "Anti-SARS Airport Evaluation Project." The first phase of this project was to develop a set of protective measures for international airports in affected areas to adopt and implement and then to send out, on the request of Contracting States, a team of inspectors to evaluate and assess airports and issue a "statement of evaluation" that the airport inspected complies with the ICAO anti-SARS protective measures. In cooperation with the World Health Organization (WHO), the first part of phase 1 was completed in early June this year, and the second part of phase 1 followed soon after. By mid-July, five international airports in Southeast Asia had been inspected and found to be in full compliance with the ICAO anti-SARS protective measures. The success of this ICAO project is believed to have contributed significantly to the recovery of international air travel and related industries now taking place. Phase 2 of the project is now being developed. It is aimed at preventing a resurgence of SARS, but it also contains elements to make the methodology developed applicable to future outbreaks of any other communicable disease in which the mode of transmission could involve aviation and/or the need to prevent the spread of the disease by air travel. PMID:14620481

  11. Low complexity efficient raw SAR data compression

    NASA Astrophysics Data System (ADS)

    Rane, Shantanu; Boufounos, Petros; Vetro, Anthony; Okada, Yu

    2011-06-01

    We present a low-complexity method for compression of raw Synthetic Aperture Radar (SAR) data. Raw SAR data is typically acquired using a satellite or airborne platform without sufficient computational capabilities to process the data and generate a SAR image on-board. Hence, the raw data needs to be compressed and transmitted to the ground station, where SAR image formation can be carried out. To perform low-complexity compression, our method uses 1-dimensional transforms, followed by quantization and entropy coding. In contrast to previous approaches, which send uncompressed or Huffman-coded bits, we achieve more efficient entropy coding using an arithmetic coder that responds to a continuously updated probability distribution. We present experimental results on compression of raw Ku-SAR data. In those we evaluate the effect of the length of the transform on compression performance and demonstrate the advantages of the proposed framework over a state-of-the-art low complexity scheme called Block Adaptive Quantization (BAQ).

  12. Possible SARS Coronavirus Transmission during Cardiopulmonary Resuscitation

    PubMed Central

    Loutfy, Mona; McDonald, L. Clifford; Martinez, Kenneth F.; Ofner, Mariana; Wong, Tom; Wallington, Tamara; Gold, Wayne L.; Mederski, Barbara; Green, Karen; Low, Donald E.

    2004-01-01

    Infection of healthcare workers with the severe acute respiratory syndrome–associated coronavirus (SARS-CoV) is thought to occur primarily by either contact or large respiratory droplet transmission. However, infrequent healthcare worker infections occurred despite the use of contact and droplet precautions, particularly during certain aerosol-generating medical procedures. We investigated a possible cluster of SARS-CoV infections in healthcare workers who used contact and droplet precautions during attempted cardiopulmonary resuscitation of a SARS patient. Unlike previously reported instances of transmission during aerosol-generating procedures, the index case-patient was unresponsive, and the intubation procedure was performed quickly and without difficulty. However, before intubation, the patient was ventilated with a bag-valve-mask that may have contributed to aerosolization of SARS-CoV. On the basis of the results of this investigation and previous reports of SARS transmission during aerosol-generating procedures, a systematic approach to the problem is outlined, including the use of the following: 1) administrative controls, 2) environmental engineering controls, 3) personal protective equipment, and 4) quality control. PMID:15030699

  13. SARS revisited: managing "outbreaks" with "communications".

    PubMed

    Menon, K U

    2006-05-01

    "Risk communications" has acquired some importance in the wake of our experience of SARS. Handled well, it helps to build mutual respect between a government or an organisation and the target groups with which it is communicating. It helps nurture public trust and confidence in getting over the crisis. The World Health Organization (WHO) has also come to recognise its importance after SARS and organised the first Expert Consultation on Outbreak Communications conference in Singapore in September 2004. This article assesses the context and the key features which worked to Singapore's advantage. Looking at the data now widely available on the Internet of the experience of SARS-infected countries like China, Taiwan, Canada, the article identifies the key areas of strategic communications in which Singapore fared particularly well. Another issue discussed is whether Singapore's experience has universal applicability or whether it is limited because of Singapore's unique cultural, historical and geographical circumstances. Finally, the article also looks at some of the post-SARS enhancements that have been put in place following the lessons learnt from SARS and the need to confront new infectious outbreaks like avian flu. PMID:16830005

  14. Statistical Approach To Determination Of Texture In SAR

    NASA Technical Reports Server (NTRS)

    Rignot, Eric J.; Kwok, Ronald

    1993-01-01

    Paper presents statistical approach to analysis of texture in synthetic-aperture-radar (SAR) images. Objective: to extract intrinsic spatial variability of distributed target from overall spatial variability of SAR image.

  15. Organ distribution of severe acute respiratory syndrome (SARS) associated coronavirus (SARS-CoV) in SARS patients: implications for pathogenesis and virus transmission pathways.

    PubMed

    Ding, Yanqing; He, Li; Zhang, Qingling; Huang, Zhongxi; Che, Xiaoyan; Hou, Jinlin; Wang, Huijun; Shen, Hong; Qiu, Liwen; Li, Zhuguo; Geng, Jian; Cai, Junjie; Han, Huixia; Li, Xin; Kang, Wei; Weng, Desheng; Liang, Ping; Jiang, Shibo

    2004-06-01

    We previously identified the major pathological changes in the respiratory and immune systems of patients who died of severe acute respiratory syndrome (SARS) but gained little information on the organ distribution of SARS-associated coronavirus (SARS-CoV). In the present study, we used a murine monoclonal antibody specific for SARS-CoV nucleoprotein, and probes specific for a SARS-CoV RNA polymerase gene fragment, for immunohistochemistry and in situ hybridization, respectively, to detect SARS-CoV systematically in tissues from patients who died of SARS. SARS-CoV was found in lung, trachea/bronchus, stomach, small intestine, distal convoluted renal tubule, sweat gland, parathyroid, pituitary, pancreas, adrenal gland, liver and cerebrum, but was not detected in oesophagus, spleen, lymph node, bone marrow, heart, aorta, cerebellum, thyroid, testis, ovary, uterus or muscle. These results suggest that, in addition to the respiratory system, the gastrointestinal tract and other organs with detectable SARS-CoV may also be targets of SARS-CoV infection. The pathological changes in these organs may be caused directly by the cytopathic effect mediated by local replication of the SARS-CoV; or indirectly as a result of systemic responses to respiratory failure or the harmful immune response induced by viral infection. In addition to viral spread through a respiratory route, SARS-CoV in the intestinal tract, kidney and sweat glands may be excreted via faeces, urine and sweat, thereby leading to virus transmission. This study provides important information for understanding the pathogenesis of SARS-CoV infection and sheds light on possible virus transmission pathways. This data will be useful for designing new strategies for prevention and treatment of SARS. PMID:15141376

  16. Characterizing hydrologic changes of Great Dismal Swamp using SAR/InSAR technology

    NASA Astrophysics Data System (ADS)

    Kim, J. W.; Lu, Z.; Zhu, Z.

    2015-12-01

    Great Dismal Swamp is one of the largest, northernmost peatlands on the Atlantic Coastal Plain, and the swamp is underlain by a thick water-logged organic soil layer (peat) made up of dead and decaying plant material. The peatlands play a role as the sink of large amount of soil organic carbon and methane. However, the disturbance of the peatland negatively impacted the ecosystem and contributed to the climate change caused by the released greenhouse gas. Our SAR/InSAR methods observed the hydrologic changes in the peatlands, which is a key factor to conserve the wetland, through several methods. First, we compared averaged SAR intensity from C- and L-band SAR sensors with groundwater level changes, and deduced a linear relationship between the SAR backscattering intensity and the groundwater level change. Second, we extracted the inundated area during wet season from InSAR coherence. Third, we measured the relative water level changes in the inundated area using the interferometric phases. Finally, we estimated the groundwater level changes corresponding to the soil moisture changes from time-series InSAR method. Our results can provide the unique opportunity to understand the occurring hydrologic and vegetation changes in the Great Dismal Swamp.

  17. Coastal Sea Level From CRYOSAT-2 SAR and SAR-In Altimetry

    NASA Astrophysics Data System (ADS)

    Andersen, O. B.; Abulaitijiang, A.; Knudsen, P.; Stenseng, L.

    2014-12-01

    Cryosat-2 offers the first ever possibility to perform coastal altimetric studies using bor SAR-altimetry and SAR-In altimetry. With this technological leap forward Cryosat-2 is now able to observe sea level in very small water bodies and also to provide coastal sea level very close to the shore. We perform an investigation into the retrieval of sea surface height around Denmark and Greenland. These regions have been chosen as the coastal regions around Denmark falls within the SAR mask and the coastal regions of Greenland falls in under the SAR-in mask employed on Cryosat-2. SAR-in was mainly used in coastal regions of Greenland because of its huge topographic changes as Cryosat-2 is designed to map the margins of the ice-sheet. The coastal region around Denmark is a test region of the EU FP7 sponsored project LOTUS esablishing SAR altimetry product in preparation for Sentinel-3. With the increased spatial resolution of Cryosat-2 SAR we provide valuable sea level observations within the Straits around Denmark which are crucial to constrain the waterflow in and out of the Baltic Sea. The investigation of SAR-in data in Greenland adds an entire new dimension to coastal altimetry. An amazing result of the investigation is the ability of Cryosat-2 to detect and recover sea level even though the coast (sealevel) is up to 15 km away from the nadir location of the satellite. This ability of capture and use returns from outside the main (-3Db) loop in theory enables Cryosat-2 SAR-in to map sea level height of fjords more frequently than the 369 days repeat.

  18. The Radarsat SAR multi-beam antenna

    NASA Astrophysics Data System (ADS)

    Martins-Camelo, L.; Cooper, R. T.; Zimcik, D. G.

    1984-10-01

    Radarsat, the Canadian radar imaging satellite, will have a Synthetic Aperture Radar (SAR) antenna as one of its sensors. The requirements on the performance of the SAR antenna are such as to make it a complex system. Radarsat is required to have some unique characteristics which present some new challenges to the antenna designers. The requirements for switchability among 4 shaped beams and high power of transmit operation are major design constraints which strongly impact on the antenna complexity, weight, and cost. A trade-off study was carried out to select the preferred antenna type for the Radarsat SAR function. The antenna types analyzed were planar-array and array-fed reflector. A set of comparison criteria was developed. The antenna concepts studied were then compared against these criteria, and a final decision was reached.

  19. Super resolution for FOPEN SAR data

    NASA Astrophysics Data System (ADS)

    Shekarforoush, Hassan; Banerjee, Amit; Chellappa, Rama

    1999-07-01

    Detecting targets occluded by foliage in Foliage penetrating (FOPEN) Ultra-Wide-Band Synthetic Aperture Radar (UWB SAR) images is an important and challenging problem. Given the different nature of FOPEN SAR imagery and very low signal- to-clutter ratio in UWB SAR data, conventional detection algorithms usually fail to yield robust target detection results on raw data with minimum false alarms. Hence improving the resolving power by means of a super-resolution algorithm plays an important role in hypothesis testing for false alarm mitigation and target localization. In this paper we present a new single-frame super-resolution algorithm based on estimating the polyphase components of the observed signal projected on an optimal basis. The estimated polyphase components are then combined into a single super-resolved image using the standard inverse polyphase transform, leading to improved target signature while suppressing noise.

  20. New approaches in interferometric SAR data processing

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    It is well established that interferometric synthetic aperture radar (SAR) images can be inverted to perform surface elevation mapping. Among the factors critical to the mapping accuracy are registration of the interfering SAR images and phase unwrapping. A novel registration algorithm is presented that determines the registration parameters through optimization. A new figure of merit is proposed that evaluates the registration result during the optimization. The phase unwrapping problem is approached through a new method involving fringe line detection. The algorithms are tested with two SEASAT SAR images of terrain near Yellowstone National Park. These images were collected on Seasat orbits 1334 and 1420, which were very close together in space, i.e., less than 100 m. The resultant elevation map is compared with the USGS digital terrain elevation model.

  1. Stop outbreak of SARS with infrared cameras

    NASA Astrophysics Data System (ADS)

    Wu, Yigang M.

    2004-04-01

    SARS (Severe Acute Respiratory Syndrome, commonly known as Atypical Pneumonia in mainland China) caused 8422 people affected and resulting in 918 deaths worldwide in half year. This disease can be transmitted by respiratory droplets or by contact with a patient's respiratory secretions. This means it can be spread out very rapidly through the public transportations by the travelers with the syndrome. The challenge was to stop the SARS carriers traveling around by trains, airplanes, coaches and etc. It is impractical with traditional oral thermometers or spot infrared thermometers to screen the tens of travelers with elevated body temperature from thousands of normal travelers in hours. The thermal imager with temperature measurement function is a logical choice for this special application although there are some limitations and drawbacks. This paper discusses the real SARS applications of industrial infrared cameras in China from April to July 2003.

  2. INTA-SAR real-time processor

    SciTech Connect

    Gomez, B.; Leon, J.

    1996-10-01

    This paper presents the INTASAR real time processor development based on a DSP open architecture for processing Synthetic Aperture Radar (SAR) signal. The final designed architecture must consider three different constraints sources: (a) SAR signal characteristics : high dynamic range, and complex SAR imaging algorithms with high computational load (multiprocessing is convenient). (b) Flexible: in connectivity and algorithms to be programmed. (c) Suitable: for on-board and ground working. The real time constraints will be defined by the image acquisition time, within it the INTASAR system will process the rawdata image and finally presents the results in the system monitor. At ground, however, the real time processing is not a constraint, but the high quality image is. The first algorithm implemented in the system was a Range - Doppler one. With the multiprocessor architecture selected, a pipeline processing method is used. 17 refs., 4 figs., 2 tabs.

  3. SARS: lessons learned from other coronaviruses.

    PubMed

    Navas-Martin, Sonia; Weiss, Susan R

    2003-01-01

    The identification of a new coronavirus as the etiological agent of severe acute respiratory syndrome (SARS) has evoked much new interest in the molecular biology and pathogenesis of coronaviruses. This review summarizes present knowledge on coronavirus molecular biology and pathogenesis with particular emphasis on mouse hepatitis virus (MHV). MHV, a member of coronavirus group 2, is a natural pathogen of the mouse; MHV infection of the mouse is considered one of the best models for the study of demyelinating disease, such as multiple sclerosis, in humans. As a result of the SARS epidemic, coronaviruses can now be considered as emerging pathogens. Future research on SARS needs to be based on all the knowledge that coronavirologists have generated over more than 30 years of research. PMID:14733734

  4. Linear Approximation SAR Azimuth Processing Study

    NASA Technical Reports Server (NTRS)

    Lindquist, R. B.; Masnaghetti, R. K.; Belland, E.; Hance, H. V.; Weis, W. G.

    1979-01-01

    A segmented linear approximation of the quadratic phase function that is used to focus the synthetic antenna of a SAR was studied. Ideal focusing, using a quadratic varying phase focusing function during the time radar target histories are gathered, requires a large number of complex multiplications. These can be largely eliminated by using linear approximation techniques. The result is a reduced processor size and chip count relative to ideally focussed processing and a correspondingly increased feasibility for spaceworthy implementation. A preliminary design and sizing for a spaceworthy linear approximation SAR azimuth processor meeting requirements similar to those of the SEASAT-A SAR was developed. The study resulted in a design with approximately 1500 IC's, 1.2 cubic feet of volume, and 350 watts of power for a single look, 4000 range cell azimuth processor with 25 meters resolution.

  5. Calibration of a polarimetric imaging SAR

    NASA Technical Reports Server (NTRS)

    Sarabandi, K.; Pierce, L. E.; Ulaby, F. T.

    1991-01-01

    Calibration of polarimetric imaging Synthetic Aperture Radars (SAR's) using point calibration targets is discussed. The four-port network calibration technique is used to describe the radar error model. The polarimetric ambiguity function of the SAR is then found using a single point target, namely a trihedral corner reflector. Based on this, an estimate for the backscattering coefficient of the terrain is found by a deconvolution process. A radar image taken by the JPL Airborne SAR (AIRSAR) is used for verification of the deconvolution calibration method. The calibrated responses of point targets in the image are compared both with theory and the POLCAL technique. Also, response of a distributed target are compared using the deconvolution and POLCAL techniques.

  6. First Results from an Airborne Ka-Band SAR Using SweepSAR and Digital Beamforming

    NASA Technical Reports Server (NTRS)

    Sadowy, Gregory A.; Ghaemi, Hirad; Hensley, Scott C.

    2012-01-01

    SweepSAR is a wide-swath synthetic aperture radar technique that is being studied for application on the future Earth science radar missions. This paper describes the design of an airborne radar demonstration that simulates an 11-m L-band (1.2-1.3 GHz) reflector geometry at Ka-band (35.6 GHz) using a 40-cm reflector. The Ka-band SweepSAR Demonstration system was flown on the NASA DC-8 airborne laboratory and used to study engineering performance trades and array calibration for SweepSAR configurations. We present an instrument and experiment overview, instrument calibration and first results.

  7. Longitudinal Analysis of Severe Acute Respiratory Syndrome (SARS) Coronavirus-Specific Antibody in SARS Patients

    PubMed Central

    Chang, Shan-Chwen; Wang, Jann-Tay; Huang, Li-Min; Chen, Yee-Chun; Fang, Chi-Tai; Sheng, Wang-Huei; Wang, Jiun-Ling; Yu, Chong-Jen; Yang, Pan-Chyr

    2005-01-01

    The serum antibodies to severe acute respiratory syndrome (SARS) coronavirus of 18 SARS patients were checked at 1 month and every 3 months after disease onset. All of them except one, who missed blood sampling at 1 month, tested positive for the immunoglobulin G (IgG) antibody at 1 month. Fifteen out of 17 tested positive for the IgM antibody at 1 month. The serum IgM antibody of most patients became undetectable within 6 months after the onset of SARS. The IgG antibody of all 17 patients, whose serum was checked 1 year after disease onset, remained positive. PMID:16339072

  8. Advanced InSAR Processing in the Footsteps of SqueeSAR

    NASA Astrophysics Data System (ADS)

    Even, Markus

    2015-05-01

    Several years ago a promising approach for processing InSAR time series was introduced under the name SqueeSAR [1]. The successful application of this framework poses some delicate questions. This paper focuses on the problem that real data do rarely behave perfectly Gaussian. An augmentation of the stochastic model underlying the phase linking step is presented and the applicability under the assumption of complex elliptically symmetric distribution is discussed. Results from tests with two time series of TerraSAR-X HRS data are presented and preliminary conclusions drawn.

  9. SAR measurement in MRI: an improved method

    NASA Astrophysics Data System (ADS)

    Romano, Rocco; Acernese, Fausto; Indovina, Pietro Luigi; Barone, Fabrizio

    2009-03-01

    During an MR procedure, the patient absorbs a portion of the transmitted RF energy, which may result in tissue heating and other adverse effects, such as alterations in visual, auditory and neural functions. The Specific Absorption Rate (SAR), in W/kg, is the RF power absorbed per unit mass of tissue and is one of the most important parameters related with thermal effects and acts as a guideline for MRI safety. Strict limits to the SAR levels are imposed by patient safety international regulations (CEI - EN 60601 - 2 - 33) and SAR measurements are required in order to verify its respect. The recommended methods for mean SAR measurement are quite problematic and often require a maintenance man intervention and long stop machine. For example, in the CEI recommended pulse energy method, the presence of a maintenance man is required in order to correctly connect the required instrumentation; furthermore, the procedure is complex and requires remarkable processing and calculus. Simpler are the calorimetric methods, also if in this case long acquisition times are required in order to have significant temperature variations and accurate heat capacity knowledge (CEI - EN 60601 - 2- 33). The phase transition method is a new method to measure SAR in MRI which has the advantages to be very simple and to overcome all the typical calorimetric method problems. It does not require in gantry temperature measurements, any specific heat or heat capacity knowledge, but only mass and time measurement. Furthermore, in this method, it is possible to show that all deposited SAR power can be considered acquired and measured.

  10. Severe Acute Respiratory Syndrome (SARS) Prevention in Taiwan

    ERIC Educational Resources Information Center

    Liu, Hsueh-Erh

    2004-01-01

    Severe Acute Respiratory Syndrome (SARS) is a newly identified respiratory disease that threatened Taiwan between April 14 and July 5, 2003. Chang Gung University experienced various SARS-related episodes, such as the postponement of classes for 7 days, the reporting of probable SARS cases, and the isolation of students under Level A and B…

  11. A tool for bistatic sar geometry determinations

    NASA Astrophysics Data System (ADS)

    Hawkins, R.; Gibson, J.; Antonik, P.; Saper, R.; Seymour, M.; St Hilaire, M.; Livingstone, C.

    The geometry of wide angle bistatic SAR is somewhat more complex than that of conventional SAR because the transmitter and receiver are displaced considerably. Constant bistatic range contours projected onto the geoid form ellipse-like profiles with the transmitter and receiver located at the two foci. Constant Doppler lines intersect the range ellipses and allow under special circumstances a simple orthogonal basis for processing and analysis. This paper illustrates a simple GUI- based tool developed in a MatLab that uses satellite orbit parameters and RADARSAT-1 data to simulate the bistatic geometry and scattering for a tower- based receiver.

  12. SAR simulation of three-dimensional scenes

    NASA Astrophysics Data System (ADS)

    Franceschetti, Giorgio; Marino, Raimundo; Migliaccio, Maurizio; Riccio, Daniele

    1994-12-01

    In this paper we examine the SAR raw signal simulation of extended mountainous natural terrain. In order to cope with this goal we need to consider some problems relative to the evaluation of the backscattering pattern and of the efficient and correct inclusion of the SAR system unit response. In particular, and with regard to the first issue inclusion of the third dimension requires accommodation of its coarse description. Subjective and objective norms in order to judge the simulation results are presented and discussed, together with a number of examples.

  13. FOPEN ultrawideband SAR imaging by wavelet interpolation

    NASA Astrophysics Data System (ADS)

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

    2003-09-01

    Wave number Domain Imaging algorithm can deal with the problem of foliage-penetrating ultra-wide band synthesis aperture radar (FOPEN UWB SAR) imaging. Stolt interpolation is a key role in Imaging Algorithm and is unevenly interpolation problem. There is no fast computation algorithm on Stolt interpolation. In this paper, A novel 4-4 tap of integer wavelet filters is used as Stolt interpolation base function. A fast interpolation algorithm is put forwards to. There is only plus and shift operation in wavelet interpolation that is easy to realize by hardware. The real data are processed to prove the wavelet interpolation valid for FOPEN UWB SAR imaging.

  14. CCD architecture for spacecraft SAR image processing

    NASA Technical Reports Server (NTRS)

    Arens, W. E.

    1977-01-01

    A real-time synthetic aperture radar (SAR) image processing architecture amenable to future on-board spacecraft applications is currently under development. Using state-of-the-art charge-coupled device (CCD) technology, low cost and power are inherent features. Other characteristics include the ability to reprogram correlation reference functions, correct for range migration, and compensate for antenna beam pointing errors on the spacecraft in real time. The first spaceborne demonstration is scheduled to be flown as an experiment on a 1982 Shuttle imaging radar mission (SIR-B). This paper describes the architecture and implementation characteristics of this initial spaceborne CCD SAR image processor.

  15. Unsupervised Segmentation Of Polarimetric SAR Data

    NASA Technical Reports Server (NTRS)

    Rignot, Eric J.; Dubois, Pascale; Van Zyl, Jakob; Kwok, Ronald; Chellappa, Rama

    1994-01-01

    Method of unsupervised segmentation of polarimetric synthetic-aperture-radar (SAR) image data into classes involves selection of classes on basis of multidimensional fuzzy clustering of logarithms of parameters of polarimetric covariance matrix. Data in each class represent parts of image wherein polarimetric SAR backscattering characteristics of terrain regarded as homogeneous. Desirable to have each class represent type of terrain, sea ice, or ocean surface distinguishable from other types via backscattering characteristics. Unsupervised classification does not require training areas, is nearly automated computerized process, and provides nonsubjective selection of image classes naturally well separated by radar.

  16. Estimating IMU heading error from SAR images.

    SciTech Connect

    Doerry, Armin Walter

    2009-03-01

    Angular orientation errors of the real antenna for Synthetic Aperture Radar (SAR) will manifest as undesired illumination gradients in SAR images. These gradients can be measured, and the pointing error can be calculated. This can be done for single images, but done more robustly using multi-image methods. Several methods are provided in this report. The pointing error can then be fed back to the navigation Kalman filter to correct for problematic heading (yaw) error drift. This can mitigate the need for uncomfortable and undesired IMU alignment maneuvers such as S-turns.

  17. Quantum-SAR extension of the spectral-SAR algorithm: application to polyphenolic anticancer bioactivity.

    PubMed

    Putz, Mihai V; Putz, Ana-Maria; Lazea, Marius; Ienciu, Luciana; Chiriac, Adrian

    2009-03-01

    Aiming to assess the role of individual molecular structures in the molecular mechanism of ligand-receptor interaction correlation analysis, the recent Spectral-SAR approach is employed to introduce the Quantum-SAR (QuaSAR) "wave" and "conversion factor" in terms of difference between inter-endpoint inter-molecular activities for a given set of compounds; this may account for inter-conversion (metabolization) of molecular (concentration) effects while indicating the structural (quantum) based influential/detrimental role on bio-/eco- effect in a causal manner rather than by simple inspection of measured values; the introduced QuaSAR method is then illustrated for a study of the activity of a series of flavonoids on breast cancer resistance protein. PMID:19399244

  18. The "Myth" of the Minimum SAR Antenna Area Constraint

    NASA Technical Reports Server (NTRS)

    Freeman, A.; Johnson, W. T. K.; Huneycutt, B.; Jordan, R.; Hensley, S.; Siqueira, P.; Curlander, J.

    1998-01-01

    A design constraint traceable ot the early days of spaceborne Synthetic Aperture Radar (SAR) is known as the minimum antenna area constraint for SAR. In this paper, it is confirmed that this constraint strictly applies only to the case where both the best possible resolution and the widest possible swath are the design goals. SAR antennas with area smaller than the constraint allows are shown to be possible, have been used on spaceborne SAR missions in the past, and should permit further, lower-cost SAR mission in the future.

  19. Cryosat-2 SAR and SAR-In Altimetry for Coastal Sea Level

    NASA Astrophysics Data System (ADS)

    Baltazar Andersen, Ole; Knudsen, Per; Abulaitijiang, Adil; Stenseng, Lars

    2015-04-01

    Cryosat-2 offers the first ever possibility to perform coastal altimetric studies using SAR-Interferometry as well as SAR altimetry. With this technological leap forward Cryosat-2 is now able to observe sea level in very small water bodies and also to provide coastal sea level very close to the shore. We perform an investigation into the retrieval of sea surface height around Denmark and Greenland. These regions have been chosen as the coastal regions around Denmark falls within the SAR mask and the coastal regions of Greenland falls in under the SAR-in mask employed on Cryosat-2. SAR-in was mainly used in coastal regions of Greenland because of its huge topographic changes as Cryosat-2 is designed to map the margins of the ice-sheet. The coastal region around Denmark is a test region of the EU sponsored project LOTUS in which With the increased spatial resolution of Cryosat-2 SAR we provide valuable sea level observations within the Straits around Denmark which are crucial to constrain the waterflow in and out of the Baltic Sea. The investigation of SAR-in data in Greenland adds an entire new dimension to coastal altimetry. An amazing result of the investigation is the ability of Cryosat-2 to detect and recover sea level even though the coast (sealevel) is up to 15 km away from the nadir location of the satellite. This ability of capture and use returns from outside the main (-3Db) loop in theory enables Cryosat-2 SAR-in to map sea level height of fjords more frequently than the 369 days repeat.

  20. Epidemic Models for SARS and Measles

    ERIC Educational Resources Information Center

    Rozema, Edward

    2007-01-01

    Recent events have led to an increased interest in emerging infectious diseases. This article applies various deterministic models to the SARS epidemic of 2003 and a measles outbreak in the Netherlands in 1999-2000. We take a historical approach beginning with the well-known logistic curve and a lesser-known extension popularized by Pearl and Reed…

  1. Acousto-Optical/Electronic Processor For SAR

    NASA Technical Reports Server (NTRS)

    Bicknell, T. J.; Farr, W. H.

    1992-01-01

    Lightweight, compact, low-power apparatus processes synthetic-aperture-radar (SAR) returns in real time, providing imagery aboard moving aircraft or spacecraft platform. Processor includes optical and electronic subsystems that, together, resolve range and azimuth coordinates of radar targets by combination of spatial and temporal integrations.

  2. SARS: An Emerging Global Microbial Threat.

    PubMed Central

    Hughes, James M.

    2004-01-01

    In March 2003, the Institute of Medicine published an update to its 1992 landmark report on emerging infections. The new report, Microbial Threats to Health: Emergence, Detection, and Response, describes the current spectrum of global microbial threats, factors affecting their emergence or resurgence, and measures that should be undertaken to effectively address them. Coincident with this publication came increasing reports of severe atypical pneumonia of unknown etiology among persons in southeast Asia. This new disease, designated severe acute respiratory syndrome (SARS), spread globally in a matter of weeks, infecting primarily close contacts of index patients (e.g., household members and healthcare workers caring for index patients) but also resulting in community transmission in some areas. An unprecedented worldwide collaborative effort was undertaken to determine the cause of the illness and implement prevention measures. A previously unrecognized coronavirus was identified as the causative agent, and health officials throughout the world struggled to implement measures to contain its spread, including isolation of suspect SARS cases and quarantine of exposed persons. The emergence of SARS is a timely reminder of the need to expect the unexpected and to ensure strong national and global public health partnerships when preparing for and responding to infectious diseases. Effectively addressing the threat of SARS will require enhanced global infectious disease surveillance, the development of rapid diagnostics, new therapies, and vaccines, implementation of aggressive evidence-based infection control strategies, and effective communication. Images Fig. 2 Fig. 3 PMID:17060979

  3. Ambiguity noise analysis of a SAR system

    NASA Astrophysics Data System (ADS)

    Tian, Haishan; Chang, Wenge; Li, Xiangyang

    2015-12-01

    The presence of range and azimuth (or Doppler) ambiguities in synthetic aperture radars (SARs) is well known. The ambiguity noise is related to the antenna pattern and the value of pulse repetition frequency (PRF). Because a new frequency modulated continuous wave (FMCW) SAR has the characters of low cost and small size, and the capacity of real-time signal processing, the antenna will likely vibrate or deform due to a lack of the stabilized platform. And the value of PRF cannot be much high because of the high computation burden for the real-time processing. The aim of this study is to access and improve the performance of a new FMCW SAR system based on the ambiguity noise. First, the quantitative analysis of the system's ambiguity noise level is performed; an antenna with low sidelobes is designed. The conclusion is that the range ambiguity noise is small; the azimuth ambiguity noise is somewhat increased, however, it is sufficiently small to have marginal influence on the image quality. Finally, the ambiguity noise level is measured using the imaging data from a Ku-band FMCW SAR. The results of this study show that the measured noise level coincides with the theoretical noise level.

  4. Discovery and SAR of hydantoin TACE inhibitors

    SciTech Connect

    Yu, Wensheng; Guo, Zhuyan; Orth, Peter; Madison, Vincent; Chen, Lei; Dai, Chaoyang; Feltz, Robert J.; Girijavallabhan, Vinay M.; Kim, Seong Heon; Kozlowski, Joseph A.; Lavey, Brian J.; Li, Dansu; Lundell, Daniel; Niu, Xiaoda; Piwinski, John J.; Popovici-Muller, Janeta; Rizvi, Razia; Rosner, Kristin E.; Shankar, Bandarpalle B.; Shih, Neng-Yang; Siddiqui, M.A.; Sun, J.; Tong, L.; Umland, S.; Wong, M.K.; Yang, D.Y.; Zhou, G.

    2010-09-03

    We disclose inhibitors of TNF-{alpha} converting enzyme (TACE) designed around a hydantoin zinc binding moiety. Crystal structures of inhibitors bound to TACE revealed monodentate coordination of the hydantoin to the zinc. SAR, X-ray, and modeling designs are described. To our knowledge, these are the first reported X-ray structures of TACE with a hydantoin zinc ligand.

  5. The Seamless SAR Archive (SSARA) Project and Other SAR Activities at UNAVCO

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    The seamless synthetic aperture radar archive (SSARA) implements a seamless distributed access system for SAR data and derived data products (i.e. interferograms). SSARA provides a unified application programming interface (API) for SAR data search and results at the Alaska Satellite Facility and UNAVCO (WInSAR and EarthScope data archives) through the use of simple web services. A federated query service was developed using the unified APIs, providing users a single search interface for both archives. Interest from the international community has prompted an effort to incorporate ESA's Virtual Archive 4 Geohazard Supersites and Natural Laboratories (GSNL) collections and other archives into the federated query service. SSARA also provides Digital Elevation Model access for topographic correction via a simple web service through OpenTopography and tropospheric correction products through JPL's OSCAR service. Additionally, UNAVCO provides data storage capabilities for WInSAR PIs with approved TerraSAR-X and ALOS-2 proposals which allows easier distribution to US collaborators on associated proposals and facilitates data access through the SSARA web services. Further work is underway to incorporate federated data discovery for GSNL across SAR, GPS, and seismic datasets provided by web services from SSARA, GSAC, and COOPEUS.

  6. Modeling and a correlation algorithm for spaceborne SAR signals

    NASA Technical Reports Server (NTRS)

    Wu, C.; Liu, K. Y.; Jin, M.

    1982-01-01

    A mathematical model of a spaceborne synthetic aperture radar (SAR) response is presented. Thhe associated SAR system performance, in terms of the resolution capability, is also discussed. The analysis of spaceborne SAR target response indicates that the SAR correlation problem is a two-dimensional one with a linear shift-variant response function. A new digital processing algorithm is proposed here in order to realize an economical digital SAR correlation system. The proposed algorithm treats the two-dimensional correlation by a combination of frequency domain fast correlation in the azimuth dimension and a time-domain convolver type of operation in the range dimension. Finally, digitally correlated SEASAT satellite SAR imagery is used in an exemplary sense to validate the SAR response model and the new digital processing technique developed.

  7. BioSAR Airborne Biomass Sensing System

    SciTech Connect

    Graham, R.L.; Johnson, P.

    2007-05-24

    This CRADA was developed to enable ORNL to assist American Electronics, Inc. test a new technology--BioSAR. BioSAR is a an airborne, low frequency (80-120 MHz {approx} FM radio frequencies) synthetic aperture radar (SAR) technology which was designed and built for NASA by ZAI-Amelex under Patrick Johnson's direction. At these frequencies, leaves and small branches are nearly transparent and the majority of the energy reflected from the forest and returned to the radar is from the tree trunks. By measuring the magnitude of the back scatter, the volume of the tree trunk and therefore the biomass of the trunks can be inferred. The instrument was successfully tested on tropical rain forests in Panama. Patrick Johnson, with American Electronics, Inc received a Phase II SBIR grant from DOE Office of Climate Change to further test and refine the instrument. Mr Johnson sought ORNL expertise in measuring forest biomass in order for him to further validate his instrument. ORNL provided ground truth measurements of forest biomass at three locations--the Oak Ridge Reservation, Weyerhaeuser Co. commercial pine plantations in North Carolina, and American Energy and Power (AEP) Co. hardwood forests in southern Ohio, and facilitated flights over these forests. After Mr. Johnson processed the signal data from BioSAR instrument, the processed data were given to ORNL and we attempted to derive empirical relationships between the radar signals and the ground truth forest biomass measurements using standard statistical techniques. We were unsuccessful in deriving such relationships. Shortly before the CRADA ended, Mr Johnson discovered that FM signal from local radio station broadcasts had interfered with the back scatter measurements such that the bulk of the signal received by the BioSAR instrument was not backscatter from the radar but rather was local radio station signals.

  8. Analysis of Multipath Pixels in SAR Images

    NASA Astrophysics Data System (ADS)

    Zhao, J. W.; Wu, J. C.; Ding, X. L.; Zhang, L.; Hu, F. M.

    2016-06-01

    As the received radar signal is the sum of signal contributions overlaid in one single pixel regardless of the travel path, the multipath effect should be seriously tackled as the multiple bounce returns are added to direct scatter echoes which leads to ghost scatters. Most of the existing solution towards the multipath is to recover the signal propagation path. To facilitate the signal propagation simulation process, plenty of aspects such as sensor parameters, the geometry of the objects (shape, location, orientation, mutual position between adjacent buildings) and the physical parameters of the surface (roughness, correlation length, permittivity)which determine the strength of radar signal backscattered to the SAR sensor should be given in previous. However, it's not practical to obtain the highly detailed object model in unfamiliar area by field survey as it's a laborious work and time-consuming. In this paper, SAR imaging simulation based on RaySAR is conducted at first aiming at basic understanding of multipath effects and for further comparison. Besides of the pre-imaging simulation, the product of the after-imaging, which refers to radar images is also taken into consideration. Both Cosmo-SkyMed ascending and descending SAR images of Lupu Bridge in Shanghai are used for the experiment. As a result, the reflectivity map and signal distribution map of different bounce level are simulated and validated by 3D real model. The statistic indexes such as the phase stability, mean amplitude, amplitude dispersion, coherence and mean-sigma ratio in case of layover are analyzed with combination of the RaySAR output.

  9. Detecting slow moving targets in SAR images

    NASA Astrophysics Data System (ADS)

    Linnehan, Robert; Perlovsky, Leonid; Mutz, Chris W.; Schindler, John

    2004-08-01

    Ground moving target indication (GMTI) radars can detect slow-moving targets if their velocities are high enough to produce distinguishable Doppler frequencies. However, no reliable technique is currently available to detect targets that fall below the minimum detectable velocity (MDV) of GMTI radars. In synthetic aperture radar (SAR) images, detection of moving targets is difficult because of target smear due to motion, which could make low-RCS targets fall below stationary ground clutter. Several techniques for SAR imaging of moving targets have been discussed in the literature. These techniques require sufficient signal-to-clutter ratio (SCR) and adequate MDV for pre-detection. Other techniques require complex changes in hardware. Extracting the maximum information from SAR image data is possible using adaptive, model-based approaches. However, these approaches lead to computational complexity, which exceeds current processing power for more than a single object in an image. This combinatorial complexity is due to the need for having to consider a large number of combinations between multiple target models and the data, while estimating unknown parameters of the target models. We are developing a technique for detecting slow-moving targets in SAR images with low signal-to-clutter ratio, without minimal velocity requirements, and without combinatorial complexity. This paper briefly summarizes the difficulties related to current model-based detection algorithms. A new concept, dynamic logic, is introduced along with an algorithm suitable for the detection of very slow-moving targets in SAR images. This new mathematical technique is inspired by the analysis of biological systems, like the human brain, which combines conceptual understanding with emotional evaluation and overcomes the combinatorial complexity of model-based techniques.

  10. Characterizing and estimating noise in InSAR and InSAR time series with MODIS

    USGS Publications Warehouse

    Barnhart, William D.; Lohman, Rowena B.

    2013-01-01

    InSAR time series analysis is increasingly used to image subcentimeter displacement rates of the ground surface. The precision of InSAR observations is often affected by several noise sources, including spatially correlated noise from the turbulent atmosphere. Under ideal scenarios, InSAR time series techniques can substantially mitigate these effects; however, in practice the temporal distribution of InSAR acquisitions over much of the world exhibit seasonal biases, long temporal gaps, and insufficient acquisitions to confidently obtain the precisions desired for tectonic research. Here, we introduce a technique for constraining the magnitude of errors expected from atmospheric phase delays on the ground displacement rates inferred from an InSAR time series using independent observations of precipitable water vapor from MODIS. We implement a Monte Carlo error estimation technique based on multiple (100+) MODIS-based time series that sample date ranges close to the acquisitions times of the available SAR imagery. This stochastic approach allows evaluation of the significance of signals present in the final time series product, in particular their correlation with topography and seasonality. We find that topographically correlated noise in individual interferograms is not spatially stationary, even over short-spatial scales (<10 km). Overall, MODIS-inferred displacements and velocities exhibit errors of similar magnitude to the variability within an InSAR time series. We examine the MODIS-based confidence bounds in regions with a range of inferred displacement rates, and find we are capable of resolving velocities as low as 1.5 mm/yr with uncertainties increasing to ∼6 mm/yr in regions with higher topographic relief.

  11. Synergistic measurements of ocean winds and waves from SAR

    NASA Astrophysics Data System (ADS)

    Zhang, Biao; Li, Xiaofeng; Perrie, William; He, Yijun

    2015-09-01

    In this study we present a synergistic method to retrieve both ocean surface wave and wind fields from spaceborne quad-polarization (QP) synthetic aperture radar (SAR) imaging mode data. This algorithm integrates QP-SAR wind vector retrieval model and the wave retrieval model, with consideration to the nonlinear mapping relationship between ocean wave spectra and SAR image spectra, in order to synergistically retrieve wind fields and wave directional spectra. The method does not require a priori information on the sea state. It combines the observed VV-polarized SAR image spectra with the retrieved wind vectors from the VH-polarized SAR image, to estimate the wind-generated wave directional spectra. The differences between the observed SAR spectra and optimal SAR image spectra associated with the wind waves are interpreted as the contributions from the swell waves. The retrieved ocean wave spectra are used to estimate the integrated spectral wave parameters such as significant wave heights, wavelengths, wave directions and wave periods. The wind and wave parameters retrieved by QP-SAR are validated against those measured by the National Data Buoy Center (NDBC) directional wave buoys under different sea states. The validation results show that the QP-SAR SAR has potential to simultaneously measure the ocean surface waves and wind fields from space.

  12. SAR Ice Classification Using Fuzzy Screening Method

    NASA Astrophysics Data System (ADS)

    Gill, R. S.

    2003-04-01

    A semi-automatic SAR sea ice classification algorithm is described. It is based on combining the information in the original SAR data with those in the three 'image' products derived from it, namely Power-to-Mean Ratio (PMR), the Gamma distribution and the second order texture parameter entropy, respectively. The latter products contain information which is often useful during the manual interpretation of the images. The technique used to fuse the information in these products is based on a method c lled Multi Experts Multi Criteria Decision Making fuzzy a screening. The Multiple Experts in this case are the above four 'image' products. The two criteria used currently for making decisions are the Kolmogorov-Smirnov distribution matching and the statistical mean of different surface classes. The algorithm classifies an image into any number of predefined classes of sea ice and open water. The representative classes of these surface types are manually identified by the user. Further, as SAR signals from sea ice covered regions and open water are ambiguous, it was found that a minimum of 4 pre-identified surface classes (calm and turbulent water and sea ice with low and high backscatter values) are required to accurately classify an image. Best results are obtained when a total of 8 surface classes (2 each of sea ice and open water in the near range and a similar number in the far range of the SAR image) are used. The main advantage of using this image classification scheme is that, like neural networks, no prior knowledge is required of the statistical distribution of the different surface types. Furthermore, unlike the methods based on neural networks, no prior data sets are required to train the algorithm. All the information needed for image classification by the method is contained in the individual SAR images and associated products. Initial results illustrating the potential of this ice classification algorithm using the RADARSAT ScanSAR Wide data are presented

  13. Simulation of SAR backscatter for forest vegetation

    NASA Astrophysics Data System (ADS)

    Prajapati, Richa; Kumar, Shashi; Agrawal, Shefali

    2016-05-01

    Synthetic Aperture Radar (SAR) is one of the most recent imaging technology to study the forest parameters. The invincible characteristics of microwave acquisition in cloudy regions and night imaging makes it a powerful tool to study dense forest regions. A coherent combination of radar polarimetry and interferometry (PolInSAR) enhances the accuracy of retrieved biophysical parameters. This paper attempts to address the issue of estimation of forest structural information caused due to instability of radar platforms through simulation of SAR image. The Terai Central Forest region situated at Haldwani area in Uttarakhand state of India was chosen as the study area. The system characteristics of PolInSAR dataset of Radarsat-2 SAR sensor was used for simulation process. Geometric and system specifications like platform altitude, center frequency, mean incidence angle, azimuth and range resolution were taken from metadata. From the field data it was observed that average tree height and forest stand density were 25 m and 300 stems/ha respectively. The obtained simulated results were compared with the sensor acquired master and slave intensity images. It was analyzed that for co-polarized horizontal component (HH), the mean values of simulated and real master image had a difference of 0.3645 with standard deviation of 0.63. Cross-polarized (HV) channel showed better results with mean difference of 0.06 and standard deviation of 0.1 while co-polarized vertical component (VV) did not show similar values. In case of HV polarization, mean variation between simulated and real slave images was found to be the least. Since cross-polarized channel is more sensitive to vegetation feature therefore better simulated results were obtained for this channel. Further the simulated images were processed using PolInSAR inversion modelling approach using three different techniques DEM differencing, Coherence Amplitude Inversion and Random Volume over Ground Inversion. DEM differencing

  14. Federated query services provided by the Seamless SAR Archive project

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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, 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 data products (i.e. interferograms). A major milestone for the first year of the SSARA project was a unified application programming interface (API) for SAR data search and results at ASF and UNAVCO (WInSAR and EarthScope data archives) through the use of simple web services. A federated query service was developed using the unified APIs, providing users a single search interface for both archives (http://www.unavco.org/ws/brokered/ssara/sar/search). A command line client that utilizes this new service is provided as an open source utility for the community on GitHub (https://github.com/bakerunavco/SSARA). Further API development and enhancements added more InSAR specific keywords and quality control parameters (Doppler centroid, faraday rotation, InSAR stack size, and perpendicular baselines). To facilitate InSAR processing, the federated query service incorporated URLs for DEM (from OpenTopography) and tropospheric corrections (from the JPL OSCAR service) in addition to the URLs for SAR data. This federated query service will provide relevant QC metadata for selecting pairs of SAR data for InSAR processing and all the URLs necessary for interferogram generation. Interest from the international community has prompted an effort to incorporate other SAR data archives (the ESA Virtual Archive 4 and the DLR TerraSAR-X_SSC Geohazard Supersites and Natural Laboratories collections) into the federated query service which provide data for researchers outside the US and North America.

  15. The flight test of Pi-SAR(L) for the repeat-pass interferometric SAR

    NASA Astrophysics Data System (ADS)

    Nohmi, Hitoshi; Shimada, Masanobu; Miyawaki, Masanori

    2006-09-01

    This paper describes the experiment of the repeat pass interferometric SAR using Pi-SAR(L). The air-borne repeat-pass interferometric SAR is expected as an effective method to detect landslide or predict a volcano eruption. To obtain a high-quality interferometric image, it is necessary to make two flights on the same flight pass. In addition, since the antenna of the Pi-SAR(L) is secured to the aircraft, it is necessary to fly at the same drift angle to keep the observation direction same. We built a flight control system using an auto pilot which has been installed in the airplane. This navigation system measures position and altitude precisely with using a differential GPS, and the PC Navigator outputs a difference from the desired course to the auto pilot. Since the air density is thinner and the speed is higher than the landing situation, the gain of the control system is required to be adjusted during the repeat pass flight. The observation direction could be controlled to some extent by adjusting a drift angle with using a flight speed control. The repeat-pass flight was conducted in Japan for three days in late November. The flight was stable and the deviation was within a few meters for both horizontal and vertical direction even in the gusty condition. The SAR data were processed in time domain based on range Doppler algorism to make the complete motion compensation. Thus, the interferometric image processed after precise phase compensation is shown.

  16. Animal models for SARS and MERS coronaviruses

    PubMed Central

    Gretebeck, Lisa M; Subbarao, Kanta

    2015-01-01

    The emergence of Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) and Middle East Respiratory Syndrome coronavirus (MERS-CoV), two strains of animal coronaviruses that crossed the species barrier to infect and cause severe respiratory infections in humans within the last 12 years, have taught us that coronaviruses represent a global threat that does not recognize international borders. We can expect to see other novel coronaviruses emerge in the future. An ideal animal model should reflect the clinical signs, viral replication and pathology seen in humans. In this review, we present factors to consider in establishing an animal model for the study of novel coronaviruses and compare the different animal models that have been employed to study SARS-CoV and MERS-CoV. PMID:26184451

  17. Synergistic combination technique for SAR image classification

    NASA Astrophysics Data System (ADS)

    Burman, Bhaskar

    1998-07-01

    Classification of earth terrain from satellite radar imagery represents an important and continually developing application of microwave remote sensing. The basic objective of this paper is to derive more information, through combining, than is present in any individual element of input data. Multispectral data has been used to provide complementary information so as to utilize a single SAR data for the purpose of land-cover classification. More recently neural networks have been applied to a number of image classification problems and have shown considerable success in exceeding the performance of conventional algorithms. In this work, a comparison study has been carried out between a conventional Maximum Likelihood (ML) classifier and a neural network (back-error-propagation) classifier in terms of classification accuracy. The results reveal that the combination of SAR and MSS data of the same scene produced better classification accuracy than either alone and the neural network classification has an edge over the conventional classification scheme.

  18. SARS: Safeguards Accounting and Reporting Software

    NASA Astrophysics Data System (ADS)

    Mohammedi, B.; Saadi, S.; Ait-Mohamed, S.

    In order to satisfy the requirements of the SSAC (State System for Accounting and Control of nuclear materials), for recording and reporting objectives; this computer program comes to bridge the gape between nuclear facilities operators and national inspection verifying records and delivering reports. The SARS maintains and generates at-facility safeguards accounting records and generates International Atomic Energy Agency (IAEA) safeguards reports based on accounting data input by the user at any nuclear facility. A database structure is built and BORLAND DELPHI programming language has been used. The software is designed to be user-friendly, to make extensive and flexible management of menus and graphs. SARS functions include basic physical inventory tacking, transaction histories and reporting. Access controls are made by different passwords.

  19. SAR observations in the Gulf of Mexico

    NASA Technical Reports Server (NTRS)

    Sheres, David

    1992-01-01

    The Gulf of Mexico (GOM) exhibits a wealth of energetic ocean features; they include the Loop Current with velocities of about 2 m/s and strong shear fronts, mesoscale eddies, double vortices, internal waves, and the outflow of the 'Mighty Mississippi' river. These energetic features can have a strong impact on the economies of the states surrounding the Gulf. Large fisheries, oil and gas production as well as pollution transport are relevant issues. These circulation features in the Gulf are invisible to conventional IR and visible satellite imagery during the Summer months due to cloud cover and uniform surface temperatures. Synthetic Aperture Radar (SAR) imagery of the Gulf does penetrate the cloud cover and shows a rich assembly of features there year-round. Below are preliminary results from GOM SAR imagery taken by SEASAT in 1978 and by the AIRSAR program in 1991.

  20. Landslide Mapping Using SqueeSAR Data

    NASA Astrophysics Data System (ADS)

    Ferretti, A.; Bellotti, F.; Alberti, S.; Allievi, J.; Del Conte, S.; Tamburini, A.; Broccolato, M.; Ratto, S.; Alberto, W.

    2011-12-01

    SqueeSAR represents the most recent advancement of PSInSAR algorithm. By exploiting signal radar returns both from Permanent and Distributed Scatterers (PS and DS), it is able to detect millimetre displacements over long periods and large areas and to obtain a significant increase in the spatial density of ground measurement points. SqueeSAR analysis is complementary to conventional geological and geomorphological studies in landslide mapping over wide areas, traditionally based on aerial-photo interpretation and field surveys. However, whenever surface displacement rates are low (mm to cm per year), assessing landslide activity is difficult or even impossible without a long-term monitoring tool, as in the case of Deep-seated Gravitational Slope Deformations (DGSD), typically characterized by large areal extent and subtle surface displacement. The availability of surface displacement time series per each measurement point allows one to have both a synoptic overview, at regional scale, as well as an in depth characterization of the instability phenomena analyzed, a meaningful support to the design of traditional monitoring networks and the efficiency testing of remedial works. When data archives are available, SqueeSAR can also provide valuable information before the installation of any terrestrial measurement system. The Italian authorities increasing interest in the application of SqueeSAR as a standard monitoring tool to help hydrogeological risk assessment, resulted in a national project, Piano Straordinario di Telerilevamento (PST), founded by the Ministry of the Environment. The aim of the project was to create the first interferometric database on a national scale for mapping unstable areas. More than 12,000 ERS and ENVISAT radar scenes acquired over Italy were processed spanning the period 1992-2010, proving that, in less than ten years, radar interferometry has become a standard monitoring tool. Recently, many regional governments in Italy have applied

  1. International collaboration in SAR ground data systems

    NASA Technical Reports Server (NTRS)

    Curlander, John C.

    1993-01-01

    A set of considerations that are pertinent to future international cooperation in the area of synthetic aperture radar (SAR) ground data systems are presented. The considerations are as follows: (1) success of future spaceborne SAR missions will require multi-agency and/or multi-national collaboration; (2) ground processing is typically performed by each agency for their user base; (3) international standards are required to achieve a uniform data product independent of the processing center; (4) to reduce the aggregate cost of the ground data systems, collaboration is required in design and development; (5) effective utilization of the data by an international user community; (6) commercialization of data products; and (7) security of data systems.

  2. SAR impulse response with residual chirps.

    SciTech Connect

    Doerry, Armin Walter

    2009-06-01

    A Linear Frequency-Modulated (LFM) chirp is a function with unit amplitude and quadratic phase characteristic. In a focused Synthetic Aperture Radar (SAR) image, a residual chirp is undesired for targets of interest, as it coarsens the manifested resolution. However, for undesired spurious signals, a residual chirp is often advantageous because it spreads the energy and thereby diminishes its peak value. In either case, a good understanding of the effects of a residual LFM chirp on a SAR Impulse Response (IPR) is required to facilitate system analysis and design. This report presents an analysis of the effects of a residual chirp on the IPR. As reference, there is a rich body of publications on various aspects of LFM chirps. A quick search reveals a plethora of articles, going back to the early 1950s. We mention here purely as trivia one of the earlier analysis papers on this waveform by Klauder, et al.

  3. Rapid Disaster Analysis based on SAR Techniques

    NASA Astrophysics Data System (ADS)

    Yang, C. H.; Soergel, U.

    2015-03-01

    Due to all-day and all-weather capability spaceborne SAR is a valuable means for rapid mapping during and after disaster. In this paper, three change detection techniques based on SAR data are discussed: (1) initial coarse change detection, (2) flooded area detection, and (3) linear-feature change detection. The 2011 Tohoku Earthquake and Tsunami is used as case study, where earthquake and tsunami events provide a complex case for this study. In (1), pre- and post-event TerraSAR-X images are coregistered accurately to produce a false-color image. Such image provides a quick and rough overview of potential changes, which is useful for initial decision making and identifies areas worthwhile to be analysed further in more depth. In (2), the post-event TerraSAR-X image is used to extract the flooded area by morphological approaches. In (3), we are interested in detecting changes of linear shape as indicator for modified man-made objects. Morphological approaches, e.g. thresholding, simply extract pixel-based changes in the difference image. However, in this manner many irrelevant changes are highlighted, too (e.g., farming activity, speckle). In this study, Curvelet filtering is applied in the difference image not only to suppress false alarms but also to enhance the change signals of linear-feature form (e.g. buildings) in settlements. Afterwards, thresholding is conducted to extract linear-shaped changed areas. These three techniques mentioned above are designed to be simple and applicable in timely disaster analysis. They are all validated by comparing with the change map produced by Center for Satellite Based Crisis Information, DLR.

  4. Synthesis and SAR of vinca alkaloid analogues.

    PubMed

    Voss, Matthew E; Ralph, Jeffery M; Xie, Dejian; Manning, David D; Chen, Xinchao; Frank, Anthony J; Leyhane, Andrew J; Liu, Lei; Stevens, Jason M; Budde, Cheryl; Surman, Matthew D; Friedrich, Thomas; Peace, Denise; Scott, Ian L; Wolf, Mark; Johnson, Randall

    2009-02-15

    Versatile intermediates 12'-iodovinblastine, 12'-iodovincristine and 11'-iodovinorelbine were utilized as substrates for transition metal based chemistry which led to the preparation of novel analogues of the vinca alkaloids. The synthesis of key iodo intermediates, their transformation into final products, and the SAR based upon HeLa and MCF-7 cell toxicity assays is presented. Selected analogues 27 and 36 show promising anticancer activity in the P388 murine leukemia model. PMID:19147348

  5. Processing of polarametric SAR images. Final report

    SciTech Connect

    Warrick, A.L.; Delaney, P.A.

    1995-09-01

    The objective of this work was to develop a systematic method of combining multifrequency polarized SAR images. It is shown that the traditional methods of correlation, hard targets, and template matching fail to produce acceptable results. Hence, a new algorithm was developed and tested. The new approach combines the three traditional methods and an interpolation method. An example is shown that demonstrates the new algorithms performance. The results are summarized suggestions for future research are presented.

  6. Interferometric SAR coherence classification utility assessment

    SciTech Connect

    Yocky, D.A.

    1998-03-01

    The classification utility of a dual-antenna interferometric synthetic aperture radar (IFSAR) is explored by comparison of maximum likelihood classification results for synthetic aperture radar (SAR) intensity images and IPSAR intensity and coherence images. The addition of IFSAR coherence improves the overall classification accuracy for classes of trees, water, and fields. A threshold intensity-coherence classifier is also compared to the intensity-only classification results.

  7. A 3-D SAR approach to IFSAR processing

    SciTech Connect

    DOERRY,ARMIN W.; BICKEL,DOUGLAS L.

    2000-03-01

    Interferometric SAR (IFSAR) can be shown to be a special case of 3-D SAR image formation. In fact, traditional IFSAR processing results in the equivalent of merely a super-resolved, under-sampled, 3-D SAR image. However, when approached as a 3-D SAR problem, a number of IFSAR properties and anomalies are easily explained. For example, IFSAR decorrelation with height is merely ordinary migration in 3-D SAR. Consequently, treating IFSAR as a 3-D SAR problem allows insight and development of proper motion compensation techniques and image formation operations to facilitate optimal height estimation. Furthermore, multiple antenna phase centers and baselines are easily incorporated into this formulation, providing essentially a sparse array in the elevation dimension. This paper shows the Polar Format image formation algorithm extended to 3 dimensions, and then proceeds to apply it to the IFSAR collection geometry. This suggests a more optimal reordering of the traditional IFSAR processing steps.

  8. Extraction of linear features on SAR imagery

    NASA Astrophysics Data System (ADS)

    Liu, Junyi; Li, Deren; Mei, Xin

    2006-10-01

    Linear features are usually extracted from SAR imagery by a few edge detectors derived from the contrast ratio edge detector with a constant probability of false alarm. On the other hand, the Hough Transform is an elegant way of extracting global features like curve segments from binary edge images. Randomized Hough Transform can reduce the computation time and memory usage of the HT drastically. While Randomized Hough Transform will bring about a great deal of cells invalid during the randomized sample. In this paper, we propose a new approach to extract linear features on SAR imagery, which is an almost automatic algorithm based on edge detection and Randomized Hough Transform. The presented improved method makes full use of the directional information of each edge candidate points so as to solve invalid cumulate problems. Applied result is in good agreement with the theoretical study, and the main linear features on SAR imagery have been extracted automatically. The method saves storage space and computational time, which shows its effectiveness and applicability.

  9. Epidemiologic clues to SARS origin in China.

    PubMed

    Xu, Rui-Heng; He, Jian-Feng; Evans, Meiron R; Peng, Guo-Wen; Field, Hume E; Yu, De-Wen; Lee, Chin-Kei; Luo, Hui-Min; Lin, Wei-Sheng; Lin, Peng; Li, Ling-Hui; Liang, Wen-Jia; Lin, Jin-Yan; Schnur, Alan

    2004-06-01

    An epidemic of severe acute respiratory syndrome (SARS) began in Foshan municipality, Guangdong Province, China, in November 2002. We studied SARS case reports through April 30, 2003, including data from case investigations and a case series analysis of index cases. A total of 1,454 clinically confirmed cases (and 55 deaths) occurred; the epidemic peak was in the first week of February 2003. Healthcare workers accounted for 24% of cases. Clinical signs and symptoms differed between children (<18 years) and older persons (> or =65 years). Several observations support the hypothesis of a wild animal origin for SARS. Cases apparently occurred independently in at least five different municipalities; early case-patients were more likely than later patients to report living near a produce market (odds ratio undefined; lower 95% confidence interval 2.39) but not near a farm; and 9 (39%) of 23 early patients, including 6 who lived or worked in Foshan, were food handlers with probable animal contact. PMID:15207054

  10. The InSAR Scientific Computing Environment

    NASA Technical Reports Server (NTRS)

    Rosen, Paul A.; Gurrola, Eric; Sacco, Gian Franco; Zebker, Howard

    2012-01-01

    We have developed a flexible and extensible Interferometric SAR (InSAR) Scientific Computing Environment (ISCE) for geodetic image processing. ISCE was designed from the ground up as a geophysics community tool for generating stacks of interferograms that lend themselves to various forms of time-series analysis, with attention paid to accuracy, extensibility, and modularity. The framework is python-based, with code elements rigorously componentized by separating input/output operations from the processing engines. This allows greater flexibility and extensibility in the data models, and creates algorithmic code that is less susceptible to unnecessary modification when new data types and sensors are available. In addition, the components support provenance and checkpointing to facilitate reprocessing and algorithm exploration. The algorithms, based on legacy processing codes, have been adapted to assume a common reference track approach for all images acquired from nearby orbits, simplifying and systematizing the geometry for time-series analysis. The framework is designed to easily allow user contributions, and is distributed for free use by researchers. ISCE can process data from the ALOS, ERS, EnviSAT, Cosmo-SkyMed, RadarSAT-1, RadarSAT-2, and TerraSAR-X platforms, starting from Level-0 or Level 1 as provided from the data source, and going as far as Level 3 geocoded deformation products. With its flexible design, it can be extended with raw/meta data parsers to enable it to work with radar data from other platforms

  11. SAR Image Segmentation Using Morphological Attribute Profiles

    NASA Astrophysics Data System (ADS)

    Boldt, M.; Thiele, A.; Schulz, K.; Hinz, S.

    2014-08-01

    In the last years, the spatial resolution of remote sensing sensors and imagery has continuously improved. Focusing on spaceborne Synthetic Aperture Radar (SAR) sensors, the satellites of the current generation (TerraSAR-X, COSMO-SykMed) are able to acquire images with sub-meter resolution. Indeed, high resolution imagery is visually much better interpretable, but most of the established pixel-based analysis methods have become more or less impracticable since, in high resolution images, self-sufficient objects (vehicle, building) are represented by a large number of pixels. Methods dealing with Object-Based Image Analysis (OBIA) provide help. Objects (segments) are groupings of pixels resulting from image segmentation algorithms based on homogeneity criteria. The image set is represented by image segments, which allows the development of rule-based analysis schemes. For example, segments can be described or categorized by their local neighborhood in a context-based manner. In this paper, a novel method for the segmentation of high resolution SAR images is presented. It is based on the calculation of morphological differential attribute profiles (DAP) which are analyzed pixel-wise in a region growing procedure. The method distinguishes between heterogeneous and homogeneous image content and delivers a precise segmentation result.

  12. Using APES for interferometric SAR imaging

    NASA Astrophysics Data System (ADS)

    Li, Jian; Palsetia, Marzban

    1996-06-01

    In this paper, we present an adaptive FIR filtering approach, which is referred to as the APES (amplitude and phase estimation of a sinusoid) algorithm, for interferometric SAR imaging. We apply the APES algorithm on the data obtained from two vertically displaced apertures of a SAR system to obtain the complex amplitude and the phase difference estimates, which are proportional to the radar cross section and the height of the scatterer, respectively, at the frequencies of interest. We also demonstrate how the APES algorithm can be applied to data matrices with large dimensions without incurring high computational overheads. We compare the APES algorithm with other FIR filtering approaches including the Capon and FFT methods. We show via both numerical and experimental examples that the adaptive FIR filtering approaches such as Capon and APES can yield more accurate spectral estimates with much lower sidelobes and narrower spectral peaks than the FFT method. We show that although the APES algorithm yields somewhat wider spectral peaks than the Capon method, the former gives more accurate overall spectral estimates and SAR images than the latter and the FFT method.

  13. Public Health Interventions and SARS Spread, 2003

    PubMed Central

    2004-01-01

    The 2003 outbreak of severe acute respiratory syndrome (SARS) was contained largely through traditional public health interventions, such as finding and isolating case-patients, quarantining close contacts, and enhanced infection control. The independent effectiveness of measures to "increase social distance" and wearing masks in public places requires further evaluation. Limited data exist on the effectiveness of providing health information to travelers. Entry screening of travelers through health declarations or thermal scanning at international borders had little documented effect on detecting SARS cases; exit screening appeared slightly more effective. The value of border screening in deterring travel by ill persons and in building public confidence remains unquantified. Interventions to control global epidemics should be based on expert advice from the World Health Organization and national authorities. In the case of SARS, interventions at a country's borders should not detract from efforts to identify and isolate infected persons within the country, monitor or quarantine their contacts, and strengthen infection control in healthcare settings. PMID:15550198

  14. Rapid extraction of water bodies from SAR imagery assisted by InSAR DEMs

    NASA Astrophysics Data System (ADS)

    Yang, Xiao-Ming; Zmuda, Andy

    1998-08-01

    In China, detailed flood maps are produced in near real time using an airborne SAR and data transmission system. Water bodies are extracted and the information is integrated with other thematic data to facilitate the rapid response to economic and humanitarian relief. One problem has been that terrain shadow on SAR images is classified as water and this proves difficult to eliminate without detailed elevation data. However interferometric processing of ERS Tandem Mission data has been used to produce a digital elevation model for a test area in China. This has been used to mask areas of terrain shadow on SAR images therefore improving the automatic classification of water bodies. The result is promising compared with the previously used method that relied on manual elimination of shadow areas.

  15. Forming rotated SAR images by real-time motion compensation.

    SciTech Connect

    Doerry, Armin Walter

    2012-12-01

    Proper waveform parameter selection allows collecting Synthetic Aperture Radar (SAR) phase history data on a rotated grid in the Fourier Space of the scene being imaged. Subsequent image formation preserves the rotated geometry to allow SAR images to be formed at arbitrary rotation angles without the use of computationally expensive interpolation or resampling operations. This should be useful where control of image orientation is desired such as generating squinted stripmaps and VideoSAR applications, among others.

  16. A fast, programmable hardware architecture for spaceborne SAR processing

    NASA Technical Reports Server (NTRS)

    Bennett, J. R.; Cumming, I. G.; Lim, J.; Wedding, R. M.

    1983-01-01

    The launch of spaceborne SARs during the 1980's is discussed. The satellite SARs require high quality and high throughput ground processors. Compression ratios in range and azimuth of greater than 500 and 150 respectively lead to frequency domain processing and data computation rates in excess of 2000 million real operations per second for C-band SARs under consideration. Various hardware architectures are examined and two promising candidates and proceeds to recommend a fast, programmable hardware architecture for spaceborne SAR processing are selected. Modularity and programmability are introduced as desirable attributes for the purpose of HTSP hardware selection.

  17. Applications of SAR Interferometry in Earth and Environmental Science Research.

    PubMed

    Zhou, Xiaobing; Chang, Ni-Bin; Li, Shusun

    2009-01-01

    This paper provides a review of the progress in regard to the InSAR remote sensing technique and its applications in earth and environmental sciences, especially in the past decade. Basic principles, factors, limits, InSAR sensors, available software packages for the generation of InSAR interferograms were summarized to support future applications. Emphasis was placed on the applications of InSAR in seismology, volcanology, land subsidence/uplift, landslide, glaciology, hydrology, and forestry sciences. It ends with a discussion of future research directions. PMID:22573992

  18. Applications of SAR Interferometry in Earth and Environmental Science Research

    PubMed Central

    Zhou, Xiaobing; Chang, Ni-Bin; Li, Shusun

    2009-01-01

    This paper provides a review of the progress in regard to the InSAR remote sensing technique and its applications in earth and environmental sciences, especially in the past decade. Basic principles, factors, limits, InSAR sensors, available software packages for the generation of InSAR interferograms were summarized to support future applications. Emphasis was placed on the applications of InSAR in seismology, volcanology, land subsidence/uplift, landslide, glaciology, hydrology, and forestry sciences. It ends with a discussion of future research directions. PMID:22573992

  19. Epipolar geometry comparison of SAR and optical camera

    NASA Astrophysics Data System (ADS)

    Li, Dong; Zhang, Yunhua

    2016-03-01

    In computer vision, optical camera is often used as the eyes of computer. If we replace camera with synthetic aperture radar (SAR), we will then enter a microwave vision of the world. This paper gives a comparison of SAR imaging and camera imaging from the viewpoint of epipolar geometry. The imaging model and epipolar geometry of the two sensors are analyzed in detail. Their difference is illustrated, and their unification is particularly demonstrated. We hope these may benefit researchers in field of computer vision or SAR image processing to construct a computer SAR vision, which is dedicated to compensate and improve human vision by electromagnetically perceiving and understanding the images.

  20. InSAR Scientific Computing Environment

    NASA Astrophysics Data System (ADS)

    Gurrola, E. M.; Rosen, P. A.; Sacco, G.; Zebker, H. A.; Simons, M.; Sandwell, D. T.

    2010-12-01

    The InSAR Scientific Computing Environment (ISCE) is a software development effort in its second year within the NASA Advanced Information Systems and Technology program. The ISCE will provide a new computing environment for geodetic image processing for InSAR sensors that will enable scientists to reduce measurements directly from radar satellites and aircraft to new geophysical products without first requiring them to develop detailed expertise in radar processing methods. The environment can serve as the core of a centralized processing center to bring Level-0 raw radar data up to Level-3 data products, but is adaptable to alternative processing approaches for science users interested in new and different ways to exploit mission data. The NRC Decadal Survey-recommended DESDynI mission will deliver data of unprecedented quantity and quality, making possible global-scale studies in climate research, natural hazards, and Earth's ecosystem. The InSAR Scientific Computing Environment is planned to become a key element in processing DESDynI data into higher level data products and it is expected to enable a new class of analyses that take greater advantage of the long time and large spatial scales of these new data, than current approaches. At the core of ISCE is both legacy processing software from the JPL/Caltech ROI_PAC repeat-pass interferometry package as well as a new InSAR processing package containing more efficient and more accurate processing algorithms being developed at Stanford for this project that is based on experience gained in developing processors for missions such as SRTM and UAVSAR. Around the core InSAR processing programs we are building object-oriented wrappers to enable their incorporation into a more modern, flexible, extensible software package that is informed by modern programming methods, including rigorous componentization of processing codes, abstraction and generalization of data models, and a robust, intuitive user interface with

  1. Polymorphism of SARS-CoV genomes.

    PubMed

    Shang, Lei; Qi, Yan; Bao, Qi-Yu; Tian, Wei; Xu, Jian-Cheng; Feng, Ming-Guang; Yang, Huan-Ming

    2006-04-01

    In this work, severe acute respiratory syndrome associated coronavirus (SARS-CoV) genome BJ202 (AY864806) was completely sequenced. The genome was directly accessed from the stool sample of a patient in Beijing. Comparative genomics methods were used to analyze the sequence variations of 116 SARS-CoV genomes (including BJ202) available in the NCBI GenBank. With the genome sequence of GZ02 as the reference, there were 41 polymorphic sites identified in BJ202 and a total of 278 polymorphic sites present in at least two of the 116 genomes. The distribution of the polymorphic sites was biased over the whole genome. Nearly half of the variations (50.4%, 140/278) clustered in the one third of the whole genome at the 3' end (19.0 kb-29.7 kb). Regions encoding Orf10-11, Orf3/4, E, M and S protein had the highest mutation rates. A total of 15 PCR products (about 6.0 kb of the genome) including 11 fragments containing 12 known polymorphic sites and 4 fragments without identified polymorphic sites were cloned and sequenced. Results showed that 3 unique polymorphic sites of BJ202 (positions 13 804, 15 031 and 20 792) along with 3 other polymorphic sites (26 428, 26 477 and 27 243) all contained 2 kinds of nucleotides. It is interesting to find that position 18379 which has not been identified to be polymorphic in any of the other 115 published SARS-CoV genomes is actually a polymorphic site. The nucleotide composition of this site is A (8) to G (6). Among 116 SARS-CoV genomes, 18 types of deletions and 2 insertions were identified. Most of them were related to a 300 bp region (27,700-28,000) which encodes parts of the putative ORF9 and ORF10-11. A phylogenetic tree illustrating the divergence of whole BJ202 genome from 115 other completely sequenced SARS-CoVs was also constructed. BJ202 was phylogeneticly closer to BJ01 and LLJ-2004. PMID:16625834

  2. Relationships between autofocus methods for SAR and self-survey techniques for SONAR. [Synthetic Aperture Radar (SAR)

    SciTech Connect

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

    1991-01-01

    Autofocus methods in SAR and self-survey techniques in SONAR have a common mathematical basis in that they both involve estimation and correction of phase errors introduced by sensor position uncertainties. Time delay estimation and correlation methods have been shown to be effective in solving the self-survey problem for towed SONAR arrays. Since it can be shown that platform motion errors introduce similar time-delay estimation problems in SAR imaging, the question arises as to whether such techniques could be effectively employed for autofocus of SAR imagery. With a simple mathematical model for motion errors in SAR, we will show why such correlation/time-delay techniques are not nearly as effective as established SAR autofocus algorithms such as phase gradient autofocus or sub-aperture based methods. This analysis forms an important bridge between signal processing methodologies for SAR and SONAR. 5 refs., 4 figs.

  3. TerraSAR InSAR Investigation of Active Crustal Deformation

    NASA Astrophysics Data System (ADS)

    Lei, L.; Burgmann, R.

    2009-12-01

    We aim to utilize advanced analysis of TerraSAR-X data to investigate the dynamics and interactions of solid Earth deformation processes, such as earthquakes and fault creep, and Earth surface processes, such as land subsidence and groundwater movements, in a densely populated, urban region, the San Francisco Bay Area. Ongoing deformation imaging reveals a number of natural hazards including elastic strain accumulation about seismologic faults, active landsliding, land subsidence and rebound, and settling of unconsolidated sediments that are highly susceptible to liquefaction. Up to now, we have ordered and received 20 more TerraSAR-X Spotlight Single Look Complex (SLC) images and a few Stripmap SLC images delivered by DLR and got a few preliminary results. The TerraSAR-X images were acquired over the San Francisco Bay Area particularly around an area of active landsliding, coastal subsidence and shallow Hayward fault creep near the city of Berkeley. Berkeley is situated between latitude 37.45 and 38.00, longitude 237.30 and 238.00. The data acquisition interval is from November, 2008 to now. Four types of Spotlight images and one type of Stripmap images in time sequence were ordered and acquired: spot_012, spot_038, spot_049, spot_075 and strip_003, having different look angles and pass directions. Access to the SAR data is via ftp about 10 days after acquisition date. The data is supplied in TerraSAR-X standard SLC COSAR (COmplex SAR) format with orbital information in an Extensible Markup Language (XML) header. The file contains integer real-complex components with double sampling and calibration constants for values. I am using ROI_PAC to do the interferograms. But ROI_PAC was designed to process the raw data rather SLC images. So there are some problems in azimuth processing with TerraSAR SLC data especially the Spotlight data. We now have some preliminary results of Stripmap interferograms and Spotlight interferograms but still work on those problems and

  4. Multi-Temporal SAR Interferometry for Landslide Monitoring

    NASA Astrophysics Data System (ADS)

    Dwivedi, R.; Narayan, A. B.; Tiwari, A.; Dikshit, O.; Singh, A. K.

    2016-06-01

    In the past few years, SAR Interferometry specially InSAR and D-InSAR were extensively used for deformation monitoring related applications. Due to temporal and spatial decorrelation in dense vegetated areas, effectiveness of InSAR and D-InSAR observations were always under scrutiny. Multi-temporal InSAR methods are developed in recent times to retrieve the deformation signal from pixels with different scattering characteristics. Presently, two classes of multi-temporal InSAR algorithms are available- Persistent Scatterer (PS) and Small Baseline (SB) methods. This paper discusses the Stanford Method for Persistent Scatterer (StaMPS) based PS-InSAR and the Small Baselines Subset (SBAS) techniques to estimate the surface deformation in Tehri dam reservoir region in Uttarkhand, India. Both PS-InSAR and SBAS approaches used sixteen ENVISAT ASAR C-Band images for generating single master and multiple master interferograms stack respectively and their StaMPS processing resulted in time series 1D-Line of Sight (LOS) mean velocity maps which are indicative of deformation in terms of movement towards and away from the satellites. From 1D LOS velocity maps, localization of landslide is evident along the reservoir rim area which was also investigated in the previous studies. Both PS-InSAR and SBAS effectively extract measurement pixels in the study region, and the general results provided by both approaches show a similar deformation pattern along the Tehri reservoir region. Further, we conclude that StaMPS based PS-InSAR method performs better in terms of extracting more number of measurement pixels and in the estimation of mean Line of Sight (LOS) velocity as compared to SBAS method. It is also proposed to take up a few major landslides area in Uttarakhand for slope stability assessment.

  5. Impact of the Regulators SigB, Rot, SarA and sarS on the Toxic Shock Tst Promoter and TSST-1 Expression in Staphylococcus aureus.

    PubMed

    Andrey, Diego O; Jousselin, Ambre; Villanueva, Maite; Renzoni, Adriana; Monod, Antoinette; Barras, Christine; Rodriguez, Natalia; Kelley, William L

    2015-01-01

    Staphylococcus aureus is an important pathogen manifesting virulence through diverse disease forms, ranging from acute skin infections to life-threatening bacteremia or systemic toxic shock syndromes. In the latter case, the prototypical superantigen is TSST-1 (Toxic Shock Syndrome Toxin 1), encoded by tst(H), and carried on a mobile genetic element that is not present in all S. aureus strains. Transcriptional regulation of tst is only partially understood. In this study, we dissected the role of sarA, sarS (sarH1), RNAIII, rot, and the alternative stress sigma factor sigB (σB). By examining tst promoter regulation predominantly in the context of its native sequence within the SaPI1 pathogenicity island of strain RN4282, we discovered that σB emerged as a particularly important tst regulator. We did not detect a consensus σB site within the tst promoter, and thus the effect of σB is likely indirect. We found that σB strongly repressed the expression of the toxin via at least two distinct regulatory pathways dependent upon sarA and agr. Furthermore rot, a member of SarA family, was shown to repress tst expression when overexpressed, although its deletion had no consistent measurable effect. We could not find any detectable effect of sarS, either by deletion or overexpression, suggesting that this regulator plays a minimal role in TSST-1 expression except when combined with disruption of sarA. Collectively, our results extend our understanding of complex multifactorial regulation of tst, revealing several layers of negative regulation. In addition to environmental stimuli thought to impact TSST-1 production, these findings support a model whereby sporadic mutation in a few key negative regulators can profoundly affect and enhance TSST-1 expression. PMID:26275216

  6. Impact of the Regulators SigB, Rot, SarA and sarS on the Toxic Shock Tst Promoter and TSST-1 Expression in Staphylococcus aureus

    PubMed Central

    Villanueva, Maite; Renzoni, Adriana; Monod, Antoinette; Barras, Christine; Rodriguez, Natalia; Kelley, William L.

    2015-01-01

    Staphylococcus aureus is an important pathogen manifesting virulence through diverse disease forms, ranging from acute skin infections to life-threatening bacteremia or systemic toxic shock syndromes. In the latter case, the prototypical superantigen is TSST-1 (Toxic Shock Syndrome Toxin 1), encoded by tst(H), and carried on a mobile genetic element that is not present in all S. aureus strains. Transcriptional regulation of tst is only partially understood. In this study, we dissected the role of sarA, sarS (sarH1), RNAIII, rot, and the alternative stress sigma factor sigB (σB). By examining tst promoter regulation predominantly in the context of its native sequence within the SaPI1 pathogenicity island of strain RN4282, we discovered that σB emerged as a particularly important tst regulator. We did not detect a consensus σB site within the tst promoter, and thus the effect of σB is likely indirect. We found that σB strongly repressed the expression of the toxin via at least two distinct regulatory pathways dependent upon sarA and agr. Furthermore rot, a member of SarA family, was shown to repress tst expression when overexpressed, although its deletion had no consistent measurable effect. We could not find any detectable effect of sarS, either by deletion or overexpression, suggesting that this regulator plays a minimal role in TSST-1 expression except when combined with disruption of sarA. Collectively, our results extend our understanding of complex multifactorial regulation of tst, revealing several layers of negative regulation. In addition to environmental stimuli thought to impact TSST-1 production, these findings support a model whereby sporadic mutation in a few key negative regulators can profoundly affect and enhance TSST-1 expression. PMID:26275216

  7. SAR digital spotlight implementation in MATLAB

    NASA Astrophysics Data System (ADS)

    Dungan, Kerry E.; Gorham, LeRoy A.; Moore, Linda J.

    2013-05-01

    Legacy synthetic aperture radar (SAR) exploitation algorithms were image-based algorithms, designed to exploit complex and/or detected SAR imagery. In order to improve the efficiency of the algorithms, image chips, or region of interest (ROI) chips, containing candidate targets were extracted. These image chips were then used directly by exploitation algorithms for the purposes of target discrimination or identification. Recent exploitation research has suggested that performance can be improved by processing the underlying phase history data instead of standard SAR imagery. Digital Spotlighting takes the phase history data of a large image and extracts the phase history data corresponding to a smaller spatial subset of the image. In a typical scenario, this spotlighted phase history data will contain much fewer samples than the original data but will still result in an alias-free image of the ROI. The Digital Spotlight algorithm can be considered the first stage in a "two-stage backprojection" image formation process. As the first stage in two-stage backprojection, Digital Spotlighting filters the original phase history data into a number of "pseudo"-phase histories that segment the scene into patches, each of which contain a reduced number of samples compared to the original data. The second stage of the imaging process consists of standard backprojection. The data rate reduction offered by Digital Spotlighting improves the computational efficiency of the overall imaging process by significantly reducing the total number of backprojection operations. This paper describes the Digital Spotlight algorithm in detail and provides an implementation in MATLAB.

  8. Utilizing feedback in adaptive SAR ATR systems

    NASA Astrophysics Data System (ADS)

    Horsfield, Owen; Blacknell, David

    2009-05-01

    Existing SAR ATR systems are usually trained off-line with samples of target imagery or CAD models, prior to conducting a mission. If the training data is not representative of mission conditions, then poor performance may result. In addition, it is difficult to acquire suitable training data for the many target types of interest. The Adaptive SAR ATR Problem Set (AdaptSAPS) program provides a MATLAB framework and image database for developing systems that adapt to mission conditions, meaning less reliance on accurate training data. A key function of an adaptive system is the ability to utilise truth feedback to improve performance, and it is this feature which AdaptSAPS is intended to exploit. This paper presents a new method for SAR ATR that does not use training data, based on supervised learning. This is achieved by using feature-based classification, and several new shadow features have been developed for this purpose. These features allow discrimination of vehicles from clutter, and classification of vehicles into two classes: targets, comprising military combat types, and non-targets, comprising bulldozers and trucks. The performance of the system is assessed using three baseline missions provided with AdaptSAPS, as well as three additional missions. All performance metrics indicate a distinct learning trend over the course of a mission, with most third and fourth quartile performance levels exceeding 85% correct classification. It has been demonstrated that these performance levels can be maintained even when truth feedback rates are reduced by up to 55% over the course of a mission.

  9. Development of VHF CARABAS II SAR

    NASA Astrophysics Data System (ADS)

    Hellsten, Hans; Ulander, Lars M.; Gustavsson, Anders; Larsson, Bjoern

    1996-06-01

    There is an increasing interest in imaging radar systems operating at low frequencies. Examples of military and civilian applications are detection of stealth-designed man- made objects, targets hidden under foliage, biomass estimation, and penetration into glaciers or ground. The developed CARABAS technology is a contribution to this field of low frequency SAR imagery. The used wavelengths offer a potential of penetration below the upper scattering layer in combination with high spatial resolution. The first prototype of the system (CARABAS I) has been tested in environments ranging from rain forests to deserts, collecting a considerably amount of data often in parallel with other SAR sensors. The work on data analysis proceeds and results obtained so far seem promising, especially for application in forested regions. The experiences gained are used in the development of a new upgraded system (CARABAS II), which is near completion and initial airborne radar tests for system verifications followed by some major field campaign are scheduled to take place during 1996. This paper will summarize the CARABAS I system characteristics and system performance evaluation. The major imperfections discovered in the radar functioning will be identified, and we explain some of the modification made in the system design for CARABAS II. A new algorithm for future real-time CARABAS data processing has been derived, with a structure well-suited for a multi-processor environment. Motion compensation and radio frequency interference mitigation are both included in this scheme. Some comments on low frequency SAR operation at UHF-based versus VHF-band will be given.

  10. A theoretical basis and methodology for the quantitative evaluation of thematic map series from SAR/InSAR data

    NASA Astrophysics Data System (ADS)

    Stevenson, Paula Jean

    2001-07-01

    Synthetic aperture radar (SAR) and interferometric SAR (InSAR) data are increasingly being used for specific operational purposes such as detailed elevation maps, detection of military targets, and coastline mapping of perpetually cloud-covered areas. One topic that has been studied extensively since the 1970's is the generation of thematic maps from this data. However, most of the relevant literature relies on highly labor-intensive approaches to yield "accurate" results for a particular scene, by fine-tuning parameters to minimize the "error" in the scene (as compared to sampled ground truth for the same scene). Consequently, it remains to be seen whether or how these data can be used to produce thematic map series efficiently and reliably in the face of varying landscapes, sensors, processors, classifiers, and output requirements. To the best of our knowledge, no one has yet examined the linked, complex, and multi-faceted issues involved in using SAR/InSAR data for this purpose; indeed, even a basis for conducting such a study has not been determined. This study adapts recent ISO (International Organization of Standardization) standards on measurand, repeatability, and reproducibility and applies them to the study of these issues. The standards are applied to analyze the range of measurement uncertainties associated with the end-to-end processes that are involved in generating thematic maps. These processes are: (1) the physical interaction of the SAR/InSAR signal with various terrain and landscape characteristics; (2) antenna characteristics and signal processing steps in generating an image; (3) image classification models and algorithms; and (4) standard map output requirements. The primary outcome is the development of a methodology through applying the ISO principles to thematic map classification of SAR/InSAR data. The methodology is expected to aid in determining the expected quality of a SAR/InSAR-based thematic map series and its fitness for intended

  11. Synthetic aperture design for increased SAR image rate

    DOEpatents

    Bielek, Timothy P.; Thompson, Douglas G.; Walker, Bruce C.

    2009-03-03

    High resolution SAR images of a target scene at near video rates can be produced by using overlapped, but nevertheless, full-size synthetic apertures. The SAR images, which respectively correspond to the apertures, can be analyzed in sequence to permit detection of movement in the target scene.

  12. An Adaptive Ship Detection Scheme for Spaceborne SAR Imagery.

    PubMed

    Leng, Xiangguang; Ji, Kefeng; Zhou, Shilin; Xing, Xiangwei; Zou, Huanxin

    2016-01-01

    With the rapid development of spaceborne synthetic aperture radar (SAR) and the increasing need of ship detection, research on adaptive ship detection in spaceborne SAR imagery is of great importance. Focusing on practical problems of ship detection, this paper presents a highly adaptive ship detection scheme for spaceborne SAR imagery. It is able to process a wide range of sensors, imaging modes and resolutions. Two main stages are identified in this paper, namely: ship candidate detection and ship discrimination. Firstly, this paper proposes an adaptive land masking method using ship size and pixel size. Secondly, taking into account the imaging mode, incidence angle, and polarization channel of SAR imagery, it implements adaptive ship candidate detection in spaceborne SAR imagery by applying different strategies to different resolution SAR images. Finally, aiming at different types of typical false alarms, this paper proposes a comprehensive ship discrimination method in spaceborne SAR imagery based on confidence level and complexity analysis. Experimental results based on RADARSAT-1, RADARSAT-2, TerraSAR-X, RS-1, and RS-3 images demonstrate that the adaptive scheme proposed in this paper is able to detect ship targets in a fast, efficient and robust way. PMID:27563902

  13. Real-time SAR change-detection using neural networks

    NASA Astrophysics Data System (ADS)

    Oliver, Christopher J.; White, Richard G.

    1990-11-01

    This paper describes the techniques evolved at RSRE for the production of undistorted, focused synthetic aperture radar (SAR) images, target detection using a neural network method and the automatic detection of changes between pairs of SAR images. All these processes are achievable in a single pipelined process operating on an input data rate in excess of 10 Mbytes/second.

  14. Fully polarimetric data from the ARL RailSAR

    NASA Astrophysics Data System (ADS)

    Ranney, Kenneth; Kirose, Getachew; Phelan, Brian; Sherbondy, Kelly

    2016-05-01

    The U.S. Army Research Laboratory (ARL) has recently upgraded the indoor, rail-mounted synthetic aperture radar (SAR) system, RailSAR, to enable collection of large amounts of low-frequency, ultrawideband (UWB) data. Our intent is to provide a research tool that is capable of emulating airborne SAR configuration and associated data collection geometries against surrogate explosive hazard threat deployments. By having such a capability, ARL's facility will afford a more rapid response to the ever changing improvised characteristics associated with explosive hazards today and in the future. Therefore, upgrades to this RailSAR tool to improve functionality and performance are needed to meet the potential rapid response assessments to be carried out. The new, lighter RailSAR cart puts less strain on the radar positioning hardware and allows the system to move smoothly along a specified portion of the rail. In previous papers, we have presented co-polarized SAR data collected using the ARL RailSAR. Recently, however, researchers at ARL have leveraged this asset to collect polarimetric data against multiple targets. This paper presents the SAR imagery resulting from these experiments and documents characteristics of certain target signatures that should be of interest to developers of automatic target detection (ATD) algorithms.

  15. Risk factors for SARS infection within hospitals in Hanoi, Vietnam.

    PubMed

    Nishiyama, Ayako; Wakasugi, Naomi; Kirikae, Teruo; Quy, Tran; Ha, Le Dang; Ban, Vo Van; Long, Hoang Thuy; Keicho, Naoto; Sasazuki, Takehiko; Kuratsuji, Tadatoshi

    2008-09-01

    We investigated a nosocomial infection of severe acute respiratory syndrome (SARS) in Vietnam in 2003 and attempted to identify risk factors for SARS infection. Of the 146 subjects who came into contact with SARS patients at Hospital A, 43 (29.5%) developed SARS, and an additional 16 (11%) were asymptomatic but SARS-coronavirus (CoV) seropositive. The asymptomatic infection rate accounted for 15.5% of the total number of infected patients at Hospital A, which was higher than that of 6.5% observed at Hospital B, to where all patients from Hospital A were eventually transported (P<0.05). At Hospital A, the risk for developing SARS was 12.6 times higher in individuals not using a mask than in those using a mask. The SARS epidemic in Vietnam resulted in numerous secondary infections due to its unknown etiology and delayed recognition at the beginning of the epidemic. The consistent and proper use of a mask was shown to be crucial for constant protection against infection with SARS. PMID:18806349

  16. The Yellowstone Fires as Observed by SIR-C SAR

    NASA Technical Reports Server (NTRS)

    Rignot, Eric; Despain, Don; Holecz, Francesco

    1996-01-01

    Covers SIR-C (Spaceborne Imaging Radar C) SAR (Synthetic Aperture Radar) imaging of the 1988 Yellowstone National Forest fires. Discusses some of the images and data collected, and some conclusions drawn from them about both the fires, and SIR-C SAR imaging capabilities.

  17. Web-GIS-based SARS epidemic situation visualization

    NASA Astrophysics Data System (ADS)

    Lu, Xiaolin

    2004-03-01

    In order to research, perform statistical analysis and broadcast the information of SARS epidemic situation according to the relevant spatial position, this paper proposed a unified global visualization information platform for SARS epidemic situation based on Web-GIS and scientific virtualization technology. To setup the unified global visual information platform, the architecture of Web-GIS based interoperable information system is adopted to enable public report SARS virus information to health cure center visually by using the web visualization technology. A GIS java applet is used to visualize the relationship between spatial graphical data and virus distribution, and other web based graphics figures such as curves, bars, maps and multi-dimensional figures are used to visualize the relationship between SARS virus tendency with time, patient number or locations. The platform is designed to display the SARS information in real time, simulate visually for real epidemic situation and offer an analyzing tools for health department and the policy-making government department to support the decision-making for preventing against the SARS epidemic virus. It could be used to analyze the virus condition through visualized graphics interface, isolate the areas of virus source, and control the virus condition within shortest time. It could be applied to the visualization field of SARS preventing systems for SARS information broadcasting, data management, statistical analysis, and decision supporting.

  18. (Q)SAR: A Tool for the Toxicologist.

    PubMed

    Steinbach, Thomas; Gad-McDonald, Samantha; Kruhlak, Naomi; Powley, Mark; Greene, Nigel

    2015-01-01

    A continuing education (CE) course at the 2014 American College of Toxicology annual meeting covered the topic of (Quantitative) Structure-Activity Relationships [(Q)SAR]. The (Q)SAR methodologies use predictive computer modeling based on predefined rules to describe the relationship between chemical structure and a chemical's associated biological activity or statistical tools to find correlations between biologic activity and the molecular structure or properties of a compound. The (Q)SAR has applications in risk assessment, drug discovery, and regulatory decision making. Pressure within industry to reduce the cost of drug development and societal pressure for government regulatory agencies to produce more accurate and timely risk assessment of drugs and chemicals have necessitated the use of (Q)SAR. Producing a high-quality (Q)SAR model depends on many factors including the choice of statistical methods and descriptors, but first and foremost the quality of the data input into the model. Understanding how a (Q)SAR model is developed and applied is critical to the successful use of such a tool. The CE session covered the basic principles of (Q)SAR, practical applications of these computational models in toxicology, how regulatory agencies use and interpret (Q)SAR models, and potential pitfalls of using them. PMID:25979517

  19. Wave retrieval from SAR imagery in the East China Sea

    NASA Astrophysics Data System (ADS)

    Lou, Xiulin; Chang, Junfang; Liu, Xiaoyan

    2015-12-01

    Synthetic aperture radar (SAR) plays an important role in measuring directional ocean wave spectra with continuous and global coverage. In this article, satellite SAR images were used to estimate the wave parameters in the East China Sea. The Max-Planck Institut (MPI) method was applied to retrieve directional wave spectra from the SAR imagers with the Simulating WAves Nearshore (SWAN) model data as the first guess wave spectra. In order to validate the SAR retrieved wave spectra, a set of buoy measurements during the SAR imaging times was collected and used. The SAR retrieved significant wave heights (SWHs) were analyzed against the buoy measurements to assess the wave retrieval of this study. The root-mean-square error between the SAR SWHs and the buoy measurements is 0.25 m, which corresponds to a relative error of 12%. The case study here shows that the SWAN model data is a potential first guess wave spectra source to the MPI method to retrieve ocean wave spectra from SAR imagery.

  20. A short note on calculating the adjusted SAR index

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A simple algebraic technique is presented for computing the adjusted SAR Index proposed by Suarez (1981). The statistical formula presented in this note facilitates the computation of the adjusted SAR without the use of either a look-up table, custom computer software or the need to compute exact a...

  1. P3 SAR exploration of biphenyl carbamate based Legumain inhibitors.

    PubMed

    Higgins, Catherine; Bouazzaoui, Samira; Gaddale, Kishore; D'Costa, Zenobia; Templeman, Amy; O'Rourke, Martin; Young, Andrew; Scott, Christopher; Harrison, Tim; Mullan, Paul; Williams, Rich

    2014-06-01

    This Letter describes the further development and SAR exploration of a novel series of Legumain inhibitors. Based upon a previously identified Legumain inhibitor from our group, we explored the SAR of the carbamate phenyl ring system to probe the P3 pocket of the enzyme. This led to the identification of a sub-nanomolar inhibitor of Legumain. PMID:24775305

  2. SARS in Singapore--key lessons from an epidemic.

    PubMed

    Tan, Chorh-Chuan

    2006-05-01

    The rapid containment of the Singapore severe acute respiratory syndrome (SARS) outbreak in 2003 involved the introduction of several stringent control measures. These measures had a profound impact on the healthcare system and community, and were associated with significant disruptions to normal life, business and social intercourse. An assessment of the relative effectiveness of the various control measures is critical in preparing for future outbreaks of a similar nature. The very "wide-net" surveillance, isolation and quarantine policy adopted was effective in ensuring progressively earlier isolation of probable SARS cases. However, it resulted in nearly 8000 contacts being put on home quarantine and 4300 on telephone surveillance, with 58 individuals eventually being diagnosed with probable SARS. A key challenge is to develop very rapid and highly sensitive tests for SARS infection, which would substantially reduce the numbers of individuals that need to be quarantined without decreasing the effectiveness of the measure. Daily temperature monitoring of all healthcare workers (HCWs) in hospitals was useful for early identification of HCWs with SARS. However, daily temperature screening of children in schools failed to pick up any SARS cases. Similarly, temperature screening at the airport and other points of entry did not yield any SARS cases. Nevertheless, the latter 2 measures probably helped to reassure the public that schools and the community were safe during the SARS outbreak. Strong political leadership and effective command, control and coordination of responses were critical factors for the containment of the outbreak. PMID:16830002

  3. Salt Kinematics and InSAR

    NASA Technical Reports Server (NTRS)

    Aftabi, Pedarm; Talbot, hristopher; Fielding, Eric

    2005-01-01

    As part of a long-term attempt to learn how the climatic and tectonic signal interact to shape a steady state mountain monitored displacement of a markers in SE termination and also near the summit of a small viscous salt fountain extruding onto the Central plateau of Iran. The marker displacements relate to the first InSAR interferograms of salt extrusion (980913 to 990620) calculated Earth tides, winds, air pressures and temperatures. In the first documented staking exercise, hammered wooden stakes vertically through the surgical marl (c. 1 Ocm deep) onto the top of crystalline salt. These stakes installed in an irregular array elongate E-W along the c.50 m high cliff marking the effective SE terminus of the glacier at Qum Kuh(Centra1 Iran) ,just to the E of a NE trending river cliff about 40 m high. We merely measured the distances between pairs of stakes with known azimuth about 2 m apart to calculate sub horizontal strain in a small part of Qum Kuh. Stakes moved and micro strains for up to 46 pairs of stakes (p strain= ((lengthl-length2)/1engthl) x 10-1) was calculated for each seven stake epochs and plotted against their azimuth on simplified array maps. The data fit well the sine curves cxpected of the maximum and minimum strain ellipses. The first documented stakes located on the SE where the InSAR image show -1 1 to 0 mm pink to purple, 0 to lOmm purple to blue, and show high activity of salt in low activity area of the InSAR image (980913 to 990620).Short term micro strains of stake tie lines record anisotropic expansions due to heating and contraction due to cooling. All epochs changed between 7 to 1 17 days (990928 to000 1 16), showed 200 to 400 micro strain lengthening and shortening. The contraction and extension existed in each epoch, but the final strain was extension in E-W in Epoch land 6, contraction in E-W direction during epochs 2-3-4-5 and 7. The second pair of stakes hammered about 20 cm deep into the deep soils(more than 1 m) , near summit

  4. Compression of Complex-Valued SAR Imagery

    SciTech Connect

    Eichel P.; Ives, R.W.

    1999-03-03

    Synthetic Aperture Radars are coherent imaging systems that produce complex-valued images of the ground. Because modern systems can generate large amounts of data, there is substantial interest in applying image compression techniques to these products. In this paper, we examine the properties of complex-valued SAR images relevant to the task of data compression. We advocate the use of transform-based compression methods but employ radically different quantization strategies than those commonly used for incoherent optical images. The theory, methodology, and examples are presented.

  5. Detection of land degradation with polarimetric SAR

    NASA Technical Reports Server (NTRS)

    Ray, Terrill W.; Farr, Tom G.; Van Zyl, Jakob J.

    1992-01-01

    Multispectral radar polarimeter data were collected over the Manix Basin Area of the Mojave desert using an airborne SAR. An analysis of the data reveals unusual polarization responses which are attributed to the formation of wind ripples on the surfaces of fields that have been abandoned for more than 5 years. This hypothesis has been confirmed through field observations, and a second-order perturbation model is shown to effectively model the polarization responses. The results demonstrate the usefulness of remote sensing techniques for the study of land degradation at synoptic scales.

  6. The Accuratre Signal Model and Imaging Processing in Geosynchronous SAR

    NASA Astrophysics Data System (ADS)

    Hu, Cheng

    With the development of synthetic aperture radar (SAR) application, the disadvantage of low earth orbit (LEO) SAR becomes more and more apparent. The increase of orbit altitude can shorten the revisit time and enlarge the coverage area in single look, and then satisfy the application requirement. The concept of geosynchronous earth orbit (GEO) SAR system is firstly presented and deeply discussed by K.Tomiyasi and other researchers. A GEO SAR, with its fine temporal resolution, would overcome the limitations of current imaging systems, allowing dense interpretation of transient phenomena as GPS time-series analysis with a spatial density several orders of magnitude finer. Until now, the related literatures about GEO SAR are mainly focused in the system parameter design and application requirement. As for the signal characteristic, resolution calculation and imaging algorithms, it is nearly blank in the related literatures of GEO SAR. In the LEO SAR, the signal model analysis adopts the `Stop-and-Go' assumption in general, and this assumption can satisfy the imaging requirement in present advanced SAR system, such as TerraSAR, Radarsat2 and so on. However because of long propagation distance and non-negligible earth rotation, the `Stop-and-Go' assumption does not exist and will cause large propagation distance error, and then affect the image formation. Furthermore the long propagation distance will result in the long synthetic aperture time such as hundreds of seconds, therefore the linear trajectory model in LEO SAR imaging will fail in GEO imaging, and the new imaging model needs to be proposed for the GEO SAR imaging processing. In this paper, considering the relative motion between satellite and earth during signal propagation time, the accurate analysis method for propagation slant range is firstly presented. Furthermore, the difference between accurate analysis method and `Stop-and-Go' assumption is analytically obtained. Meanwhile based on the derived

  7. Single Baseline Tomography SAR for Forest Above Ground Biomass Estimation

    NASA Astrophysics Data System (ADS)

    Li, Wenmei; Chen, Erxue; Li, Zengyuan; Wang, Xinshuang; Feng, Qi

    2013-01-01

    Single baseline tomography SAR is used for forest height estimation as its little restriction on the number of baselines and configurations of tracks in recent years. There existed two kinds of single baseline tomography SAR techniques, the polarimetric coherence tomography (PCT) and the sum of Kronecker product (SKP), algebraic synthesis (AS) and Capon spectral estimator approach (SKP-AS-Capon). Few researches on forest above ground biomass (AGB) estimation are there using single baseline tomography SAR. In this paper, PCT and SKP-AS-Capon approaches are proposed for forest AGB estimation. L-band data set acquired by E-SAR airborne system in 2003 for the forest test site in Traunstein, is used for this experiment. The result shows that single baseline polarimetric tomography SAR can obtain forest AGB in forest stand scale, and SKP-AS-Capon method has better detailed vertical structure information, while the Freeman 3-component combined PCT approach gets a homogenous vertical structure in forest stand.

  8. Assessing ScanSAR Interferometry for Deformation Studies

    NASA Astrophysics Data System (ADS)

    Buckley, S. M.; Gudipati, K.

    2007-12-01

    There is a trend in civil satellite SAR mission design to implement an imaging strategy that incorporates both stripmap mode and ScanSAR imaging. This represents a compromise between high resolution data collection and a desire for greater spatial coverage and more frequent revisit times. However, mixed mode imaging can greatly reduce the number of stripmap images available for measuring subtle ground deformation. Although ScanSAR-ScanSAR and ScanSAR-stripmap repeat-pass interferometry have been demonstrated, these approaches are infrequently used for single interferogram formation and nonexistent for InSAR time series analysis. For future mission design, e.g., a dedicated US InSAR mission, the effect of various ScanSAR system parameter choices on InSAR time series analysis also remains unexplored. Our objective is to determine the utility of ScanSAR differential interferometry. We will demonstrate the use of ScanSAR interferograms for several previous deformation studies: localized and broad-scale urban land subsidence, tunneling, volcanic surface movements and several examples associated with the seismic cycle. We also investigate the effect of various ScanSAR burst synchronization levels on our ability to detect and make quality measurements of deformation. To avoid the issues associated with Envisat ScanSAR burst alignment and to exploit a decade of InSAR measurements, we simulate ScanSAR data by bursting (throwing away range lines of) ERS-1/2 data. All the burst mode datasets are processed using a Modified SPECAN algorithm. To investigate the effects of burst misalignment, a number of cases with varying degrees of burst overlap are considered. In particular, we look at phase decorrelation as a function of percentage of burst overlap. Coherence clearly reduces as the percentage of overlap decreases and we find a useful threshold of 40-70% burst overlap depending on the study site. In order to get a more generalized understanding for different surface conditions

  9. Ship detection in SAR images using efficient land masking methods

    NASA Astrophysics Data System (ADS)

    Mashaly, Ahmed S.; AbdElkawy, Ezz F.; Mahmoud, Tarek A.

    2014-06-01

    Synthetic Aperture Radar (SAR) has an important contribution in monitoring ships in the littoral regions. This stems from the substantial information that SAR images have which can facilitate the ships detection operation. Coastline images produced by SAR suffer from many deficiencies which arise from the presence of speckles and strong signals returned from land and rough sea. The first step in many ship detection systems is to mark and reject the land in SAR images (land masking). This is performed to reduce the number of false alarms that might be introduced if the land is processed by ship detector. In this paper, two powerful methods for land masking are introduced. One is based on mathematical morphology while the other is based on Lee-Jurkevich coastline detection and mean estimator algorithm. From experimental results, the proposed methods give promising results for both strongly marking the land area in SAR images and efficiently preserving the details of coastlines as well.

  10. Internal wave parameters retrieval from space-borne SAR image

    NASA Astrophysics Data System (ADS)

    Fan, Kaiguo; Fu, Bin; Gu, Yanzhen; Yu, Xingxiu; Liu, Tingting; Shi, Aiqin; Xu, Ke; Gan, Xilin

    2015-12-01

    Based on oceanic internal wave SAR imaging mechanism and the microwave scattering imaging model for oceanic surface features, we developed a new method to extract internal wave parameters from SAR imagery. Firstly, the initial wind fields are derived from NCEP reanalysis data, the sea water density and oceanic internal wave pycnocline depth are estimated from the Levites data, the surface currents induced by the internal wave are calculated according to the KDV equation. The NRCS profile is then simulated by solving the action balance equation and using the sea surface radar backscatter model. Both the winds and internal wave pycnocline depth are adjusted by using the dichotomy method step by step to make the simulated data approach the SAR image. Then, the wind speed, pycnocline depth, the phase speed, the group velocity and the amplitude of internal wave can be retrieved from SAR imagery when a best fit between simulated signals and the SAR image appears. The method is tested on one scene SAR image near Dongsha Island, in the South China Sea, results show that the simulated oceanic internal wave NRCS profile is in good agreement with that on the SAR image with the correlation coefficient as high as 90%, and the amplitude of oceanic internal wave retrieved from the SAR imagery is comparable with the SODA data. Besides, the phase speeds retrieved from other 16 scene SAR images in the South China Sea are in good agreement with the empirical formula which describes the relations between internal wave phase speed and water depths, both the root mean square and relative error are less than 0.11 m•s-1 and 7%, respectively, indicating that SAR images are useful for internal wave parameters retrieval and the method developed in this paper is convergent and applicable.

  11. Comparison and Analysis of Geometric Correction Models of Spaceborne SAR

    PubMed Central

    Jiang, Weihao; Yu, Anxi; Dong, Zhen; Wang, Qingsong

    2016-01-01

    Following the development of synthetic aperture radar (SAR), SAR images have become increasingly common. Many researchers have conducted large studies on geolocation models, but little work has been conducted on the available models for the geometric correction of SAR images of different terrain. To address the terrain issue, four different models were compared and are described in this paper: a rigorous range-doppler (RD) model, a rational polynomial coefficients (RPC) model, a revised polynomial (PM) model and an elevation derivation (EDM) model. The results of comparisons of the geolocation capabilities of the models show that a proper model for a SAR image of a specific terrain can be determined. A solution table was obtained to recommend a suitable model for users. Three TerraSAR-X images, two ALOS-PALSAR images and one Envisat-ASAR image were used for the experiment, including flat terrain and mountain terrain SAR images as well as two large area images. Geolocation accuracies of the models for different terrain SAR images were computed and analyzed. The comparisons of the models show that the RD model was accurate but was the least efficient; therefore, it is not the ideal model for real-time implementations. The RPC model is sufficiently accurate and efficient for the geometric correction of SAR images of flat terrain, whose precision is below 0.001 pixels. The EDM model is suitable for the geolocation of SAR images of mountainous terrain, and its precision can reach 0.007 pixels. Although the PM model does not produce results as precise as the other models, its efficiency is excellent and its potential should not be underestimated. With respect to the geometric correction of SAR images over large areas, the EDM model has higher accuracy under one pixel, whereas the RPC model consumes one third of the time of the EDM model. PMID:27347973

  12. Real-time optical processor prototype for remote SAR applications

    NASA Astrophysics Data System (ADS)

    Marchese, Linda; Doucet, Michel; Harnisch, Bernd; Suess, Martin; Bourqui, Pascal; Legros, Mathieu; Desnoyers, Nichola; Guillot, Ludovic; Mercier, Luc; Savard, Maxime; Martel, Anne; Châteauneuf, François; Bergeron, Alain

    2009-09-01

    A Compact Real-Time Optical SAR Processor has been successfully developed and tested. SAR, or Synthetic Aperture Radar, is a powerful tool providing enhanced day and night imaging capabilities. SAR systems typically generate large amounts of information generally in the form of complex data that are difficult to compress. Specifically, for planetary missions and unmanned aerial vehicle (UAV) systems with limited communication data rates this is a clear disadvantage. SAR images are typically processed electronically applying dedicated Fourier transformations. This, however, can also be performed optically in real-time. Indeed, the first SAR images have been optically processed. The optical processor architecture provides inherent parallel computing capabilities that can be used advantageously for the SAR data processing. Onboard SAR image generation would provide local access to processed information paving the way for real-time decision-making. This could eventually benefit navigation strategy and instrument orientation decisions. Moreover, for interplanetary missions, onboard analysis of images could provide important feature identification clues and could help select the appropriate images to be transmitted to Earth, consequently helping bandwidth management. This could ultimately reduce the data throughput requirements and related transmission bandwidth. This paper reviews the design of a compact optical SAR processor prototype that would reduce power, weight, and size requirements and reviews the analysis of SAR image generation using the table-top optical processor. Various SAR processor parameters such as processing capabilities, image quality (point target analysis), weight and size are reviewed. Results of image generation from simulated point targets as well as real satellite-acquired raw data are presented.

  13. Comparison and Analysis of Geometric Correction Models of Spaceborne SAR.

    PubMed

    Jiang, Weihao; Yu, Anxi; Dong, Zhen; Wang, Qingsong

    2016-01-01

    Following the development of synthetic aperture radar (SAR), SAR images have become increasingly common. Many researchers have conducted large studies on geolocation models, but little work has been conducted on the available models for the geometric correction of SAR images of different terrain. To address the terrain issue, four different models were compared and are described in this paper: a rigorous range-doppler (RD) model, a rational polynomial coefficients (RPC) model, a revised polynomial (PM) model and an elevation derivation (EDM) model. The results of comparisons of the geolocation capabilities of the models show that a proper model for a SAR image of a specific terrain can be determined. A solution table was obtained to recommend a suitable model for users. Three TerraSAR-X images, two ALOS-PALSAR images and one Envisat-ASAR image were used for the experiment, including flat terrain and mountain terrain SAR images as well as two large area images. Geolocation accuracies of the models for different terrain SAR images were computed and analyzed. The comparisons of the models show that the RD model was accurate but was the least efficient; therefore, it is not the ideal model for real-time implementations. The RPC model is sufficiently accurate and efficient for the geometric correction of SAR images of flat terrain, whose precision is below 0.001 pixels. The EDM model is suitable for the geolocation of SAR images of mountainous terrain, and its precision can reach 0.007 pixels. Although the PM model does not produce results as precise as the other models, its efficiency is excellent and its potential should not be underestimated. With respect to the geometric correction of SAR images over large areas, the EDM model has higher accuracy under one pixel, whereas the RPC model consumes one third of the time of the EDM model. PMID:27347973

  14. An introduction to the interim digital SAR processor and the characteristics of the associated Seasat SAR imagery

    NASA Technical Reports Server (NTRS)

    Wu, C.; Barkan, B.; Huneycutt, B.; Leang, C.; Pang, S.

    1981-01-01

    Basic engineering data regarding the Interim Digital SAR Processor (IDP) and the digitally correlated Seasat synthetic aperature radar (SAR) imagery are presented. The correlation function and IDP hardware/software configuration are described, and a preliminary performance assessment presented. The geometric and radiometric characteristics, with special emphasis on those peculiar to the IDP produced imagery, are described.

  15. Relations of SARS-Related Stressors and Coping to Chinese College Students' Psychological Adjustment during the 2003 Beijing SARS Epidemic

    ERIC Educational Resources Information Center

    Main, Alexandra; Zhou, Qing; Ma, Yue; Luecken, Linda J.; Liu, Xin

    2011-01-01

    This study examined the main and interactive relations of stressors and coping related to severe acute respiratory syndrome (SARS) with Chinese college students' psychological adjustment (psychological symptoms, perceived general health, and life satisfaction) during the 2003 Beijing SARS epidemic. All the constructs were assessed by self-report…

  16. Ultrawideband VHF SAR design and measurements

    NASA Astrophysics Data System (ADS)

    Hellsten, Hans; Froelind, Per-Olov; Gustafsson, Anders; Jonsson, T.; Larsson, Bjoern; Stenstroem, Gunnar; Binder, Bradley T.; Mirkin, Mitchell I.; Ayasli, Serpil

    1994-07-01

    CARABAS, an acronym for `coherent all radio band sensing,' is an airborne, horizontal-polarization SAR operating across the frequency band 20 to 90 MHz, conceived, designed and built by FOA in Sweden. The original motivation for designing such a low frequency system was that a large relative or fractional bandwidth could be achieved at low frequencies. For reasons to be explained, a large fractional bandwidth was considered to be of potential benefit for radar detection in severe clutter environments. A feasibility study of a short wave ultra-wideband radar started at FOA in 1985. Actual construction of the CARABAS system commenced 1987, aircraft integration took place during 1991 and the first radar tests were conducted in early 1992. From the fall of 1992 onwards, field campaigns and evaluation studies have been conducted as a joint effort between FOA and MIT Lincoln Laboratory in the US. This article will focus on experiences concerning foliage penetration with the system. First we touch upon the CARABAS system characteristics, outline the arguments behind a large fractional bandwidth VHF-band SAR approach to foliage penetration, and finally present some early experimental results. We refer to other papers for a fuller explanation of the system, for more details of image calibration, and for results concerning underground imaging.

  17. Coherent aspect-dependent SAR image formation

    NASA Astrophysics Data System (ADS)

    Chaney, Ronald D.; Willsky, Alan S.; Novak, Leslie M.

    1994-06-01

    An adaptive image formation algorithm is proposed to exploit the aspect-angle dependence of man-made scatterers in foliage penetrating (FOPEN) synthetic aperture radar (SAR). Man-made scatterers often exhibit a strong dependence on the aspect angle between the orientation of the scatterer and the line of sight of the radar. More specifically, the return from a man-made target is greater when the target is oriented broadside with respect to the radar. Conventional SAR image formation processing assumes that backscatter is independent of the aspect angle; by relaxing this assumption, it is possible to reformulate the image formation process to improve the separability of man-made scatterers vs. natural clutter. We propose an image formation process that adapts the length and position of the aperture used during the cross-range compression stage. The algorithm identifies the locations that are likely to correspond to aspect- dependent scatterers. In the vicinity of such scatterers, the algorithm chooses the aperture to match the expected return from a man-made scatterer. Elsewhere, the algorithm uses the full aperture. The resulting imagery enhances man-made targets relative to the background clutter and facilitates improved detection performance.

  18. Classification SAR targets with support vector machine

    NASA Astrophysics Data System (ADS)

    Cao, Lanying

    2007-02-01

    With the development of Synthetic Aperture Radar (SAR) technology, automatic target recognition (ATR) is becoming increasingly important. In this paper, we proposed a 3-class target classification system in SAR images. The system is based on invariant wavelet moments and support vector machine (SVM) algorithm. It is a two-stage approach. The first stage is to extract and select a small set of wavelet invariant moment features to indicate target images. The wavelet invariant moments take both advantages of the wavelet inherent property of multi-resolution analysis and moment invariants quality of invariant to translation, scaling changes and rotation. The second stage is classification of targets with SVM algorithm. SVM is based on the principle of structural risk minimization (SRM), which has been shown better than the principle of empirical risk minimization (ERM) which is used by many conventional networks. To test the performance and efficiency of the proposed method, we performed experiments on invariant wavelet moments, different kernel functions, 2-class identification, and 3-class identification. Test results show that wavelet invariant moments indicate the target effectively; linear kernel function achieves better results than other kernel functions, and SVM classification approach performs better than conventional nearest distance approach.

  19. SAR Image despeckling via sparse representation

    NASA Astrophysics Data System (ADS)

    Wang, Zhongmei; Yang, Xiaomei; Zheng, Liang

    2014-11-01

    SAR image despeckling is an active research area in image processing due to its importance in improving the quality of image for object detection and classification.In this paper, a new approach is proposed for multiplicative noise in SAR image removal based on nonlocal sparse representation by dictionary learning and collaborative filtering. First, a image is divided into many patches, and then a cluster is formed by clustering log-similar image patches using Fuzzy C-means (FCM). For each cluster, an over-complete dictionary is computed using the K-SVD method that iteratively updates the dictionary and the sparse coefficients. The patches belonging to the same cluster are then reconstructed by a sparse combination of the corresponding dictionary atoms. The reconstructed patches are finally collaboratively aggregated to build the denoised image. The experimental results show that the proposed method achieves much better results than many state-of-the-art algorithms in terms of both objective evaluation index (PSNR and ENL) and subjective visual perception.

  20. Rapid inactivation of SARS-like coronaviruses.

    SciTech Connect

    Kapil, Sanjay; Oberst, R. D.; Bieker, Jill Marie; Tucker, Mark David; Souza, Caroline Ann; Williams, Cecelia Victoria

    2004-03-01

    Chemical disinfection and inactivation of viruses is largely understudied, but is very important especially in the case of highly infectious viruses. The purpose of this LDRD was to determine the efficacy of the Sandia National Laboratories developed decontamination formulations against Bovine Coronavirus (BCV) as a surrogate for the coronavirus that causes Severe Acute Respiratory Syndrome (SARS) in humans. The outbreak of SARS in late 2002 resulted from a highly infectious virus that was able to survive and remain infectious for extended periods. For this study, preliminary testing with Escherichia coli MS-2 (MS-2) and Escherichia coli T4 (T4) bacteriophages was conducted to develop virucidal methodology for verifying the inactivation after treatment with the test formulations following AOAC germicidal methodologies. After the determination of various experimental parameters (i.e. exposure, concentration) of the formulations, final testing was conducted on BCV. All experiments were conducted with various organic challenges (horse serum, bovine feces, compost) for results that more accurately represent field use condition. The MS-2 and T4 were slightly more resistant than BCV and required a 2 minute exposure while BCV was completely inactivated after a 1 minute exposure. These results were also consistent for the testing conducted in the presence of the various organic challenges indicating that the test formulations are highly effective for real world application.

  1. The Ecosystems SAR (EcoSAR) an Airborne P-band Polarimetric InSAR for the Measurement of Vegetation Structure, Biomass and Permafrost

    NASA Technical Reports Server (NTRS)

    Rincon, Rafael F.; Fatoyinbo, Temilola; Ranson, K. Jon; Osmanoglu, Batuhan; Sun, Guoqing; Deshpande, Manohar D.; Perrine, Martin L.; Du Toit, Cornelis F.; Bonds, Quenton; Beck, Jaclyn; Lu, Daniel

    2014-01-01

    EcoSAR is a new synthetic aperture radar (SAR) instrument being developed at the NASA/ Goddard Space Flight Center (GSFC) for the polarimetric and interferometric measurements of ecosystem structure and biomass. The instrument uses a phased-array beamforming architecture and supports full polarimetric measurements and single pass interferometry. This Instrument development is part of NASA's Earth Science Technology Office Instrument Incubator Program (ESTO IIP).

  2. 76 FR 20822 - Proposed Information Collection (Servicer's Staff Appraisal Reviewer (SAR) Application) Activity...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-13

    ... AFFAIRS Proposed Information Collection (Servicer's Staff Appraisal Reviewer (SAR) Application) Activity... (SAR) Application, VA Form 26-0829. OMB Control Number: 2900-0715. Type of Review: Extension of a... approval as Staff Appraisal Reviewer (SAR). Servicers SAR's will have the authority to review real...

  3. Interferometric SAR Persistent Scatterer Analysis of Mayon volcano, Albay, Philippines

    NASA Astrophysics Data System (ADS)

    Bato, M. P.; Lagmay, A. A.; Paguican, E. R.

    2011-12-01

    Persistent Scatterer Interferometry (PSInSAR) is a new method of interferometric processing that overcomes the limitations of conventional Synthetic Aperture Radar differential interferometry (DInSAR) and is capable of detecting millimeter scale ground displacements. PSInSAR eliminate anomalies due to atmospheric delays and temporal and geometric decorrelation eminent in tropical regions by exploiting the temporal and spatial characteristics of radar interferometric signatures derived from time-coherent point-wise targets. In this study, PSInSAR conducted in Mayon Volcano, Albay Province, Bicol, Philippines, reveal tectonic deformation passing underneath the volcano. Using 47 combined ERS and ENVISAT ascending and descending imageries, differential movement between the northern horst and graben on which Mayon volcano lies, is as much as 2.5 cm/year in terms of the line-of-sight (LOS) change in the radar signal. The northern horst moves in the northwest direction whereas the graben moves mostly downward. PSInSAR results when coupled with morphological interpretation suggest left-lateral oblique-slip movement of the northern bounding fault of the Oas graben. The PSInSAR results are validated with dGPS measurements. This work presents the functionality of PSInSAR in a humid tropical environment and highlights the probable landslide hazards associated with an oversteepened volcano that may have been further deformed by tectonic activity.

  4. Flight demonstration of image fix-taking with SAR

    SciTech Connect

    Gibbs, R.; Bottkol, M.; Owen, T.

    1993-06-11

    Airborne Synthetic Aperture Radar (SAR) uses coherent radar processing techniques to image ground reflectors. After processing, range and Doppler can be associated with any feature of interest in the final image. The location of any imaged feature can be estimated using a Kalman filter to combine these data with GPS and INS navigation data. This paper reports on the results of a flight demonstration of such a system, using an airborne SAR developed at Sandia. Collected data consisted of multiple SAR images containing surveyed reflectors. GPS/INS output taken aboard the aircraft, and GPS output recorded at surveyed ground stations. These data were post-processed at Sandia and at Draper Laboratory to obtain a navigation solution based on differential GPS and to demonstrate SAR fix-taking performance. This study successfully demonstrates accuracy of about 1 meter for fixing the position of a point imaged with SAR from an airborne platform. Because differential GPS was used, the navigation error was of about the same magnitude as the SAR range measurement error. Consequently, the measurements served primarily to fix the SAR image rather than to update the navigator.

  5. Polarimetric SAR Tomopgraphy With TerraSAR-X By Means Of Distributed Compressed Sensing

    NASA Astrophysics Data System (ADS)

    Aguilera, E.; Nannini, M.; Antonello, A.; Marotti, L.; Prats, P.; Reigber, A.

    2012-01-01

    In SAR tomography, the vertical reflectivity function for every azimuth-range pixel is usually recovered by processing data collected using a defined repeat-pass acquisition geometry. A common and appealing approach is to generate a synthetic aperture in the elevation direction through imaging from parallel tracks. However, the quality of conventional reconstruction methods is generally dictated by the Nyquist rate, which can be considerably high. In an attempt to reduce this rate, we propose a new tomographic focusing approach that exploits correlations between neighboring azimuth-range pixels and polarimetric channels. As a matter of fact, this can be done under the framework of Distributed Com- pressed Sensing (DCS), which stems from Compressed Sensing (CS) theory, thus also exploiting sparsity in the tomographic signal. Results demonstrating the potential of the DCS methodology will be validated, for the first time, using dual-polarized data acquired at X-band by the TerraSAR-X spaceborne system.

  6. The TerraSAR-L Interferometric Mission Objectives

    NASA Astrophysics Data System (ADS)

    Zink, M.

    2004-06-01

    TerraSAR-L is the new imaging radar mission of the European Space Agency. The platform, based on the novel Snapdragon concept, is built around the active phase array antenna of the L-band Synthetic Aperture Radar (SAR). Specification of the L-SAR has been guided by careful analysis of the product requirements resulting in a robust baseline design with considerable margins. Besides having a commercial role for the provision of geo-information products, TerraSAR-L will contribute to the Global Monitoring for Environment and Security (GMES) initiative and serve the scientific user community. Interferometry (INSAR) is a key element behind a number of mission objectives. A L-band SAR in a 14-day repeat orbit is an ideal sensor for solid earth applications (earth quake and volcano monitoring, landslides and subsidence) relying on differential interferometry. L-band penetration of vegetation cover facilitates these applications also over vegetated surfaces. Because of the high coherence, L-band is also the preferred frequency for monitoring ice sheet and glacier dynamics. Highly accurate orbit control (orbital tube <100m) and special wideband INSAR modes are required to support these applications globally and systematically. Precise burst synchronisation enables repeat-pass ScanSAR interferometry and global coverage within the short repeat cycle. A feasibility study into cartwheel constellations flying in close formation with TerraSAR-L revealed the potential for generating Digital Elevation Models (DEMs) of unprecedented quality (2m relative height accuracy @ 12m posting). The TerraSAR-L operations strategy is based on a long-term systematic and repetitive acquisition scenario to ensure consistent data archives and to maximise the exploitation of this very powerful SAR system.

  7. A Time Domain Along-Track SAR Interferometry Method

    NASA Astrophysics Data System (ADS)

    Cao, N.; Lee, H.; Jung, H. C.

    2015-12-01

    Differential interferometric synthetic aperture radar (DInSAR) has already been proven to be a useful technique for measuring ground displacement at millimeter level. One major drawback of traditional DInSAR technique is that only 1-D deformation in slant range direction can be detected. In order to obtain along-track displacement using a single InSAR pair, two major attempts have been made. The first one is based on cross-correlation between two SAR amplitude images. The second attempt is based on split-beam processing to generate two SAR images from forward- and backward-looking beams. Comparing with the former method, this multiple-aperture SAR interferometry (MAI) can achieve much better measurement accuracy. The major drawback of the MAI method is degraded signal to noise ratio (SNR) and along-track resolution since total along-track integration time decreases in the split-beam procedure. In order to improve the SNR and along-track resolution as well as to extract the terrain displacement in the along-track direction, a time domain along-track SAR interferometry method is proposed in this study. Using traditional time domain backprojection method, the phase component corresponding to slant range direction offset can be estimated and removed from the range compressed SAR signal. Then a phase estimation procedure is implemented to obtain the phase component in the along-track direction. Using ALOS PALSAR data over Kilauea Volcano area in Hawai'i, our experimental results demonstrate the improved performance of the proposed method in extracting 2-D terrain deformation map from one pair of SAR images.

  8. Indoor experimental facility for airborne synthetic aperture radar (SAR) configurations - rail-SAR

    NASA Astrophysics Data System (ADS)

    Kirose, Getachew; Phelan, Brian R.; Sherbondy, Kelly D.; Ranney, Kenneth I.; Koenig, Francois; Narayanan, Ram M.

    2014-05-01

    The Army Research Laboratory (ARL) is developing an indoor experimental facility to evaluate and assess airborne synthetic-aperture-radar-(SAR)-based detection capabilities. The rail-SAR is located in a multi-use facility that also provides a base for research and development in the area of autonomous robotic navigation. Radar explosive hazard detection is one key sensordevelopment area to be investigated at this indoor facility. In particular, the mostly wooden, multi-story building houses a two (2) story housing structure and an open area built over a large sandbox. The housing structure includes reconfigurable indoor walls which enable the realization of multiple See-Through-The-Wall (STTW) scenarios. The open sandbox, on the other hand, allows for surface and buried explosive hazard scenarios. The indoor facility is not rated for true explosive hazard materials so all targets will need to be inert and contain surrogate explosive fills. In this paper we discuss the current system status and describe data collection exercises conducted using canonical targets and frequencies that may be of interest to designers of ultra-wideband (UWB) airborne, ground penetrating SAR systems. A bi-static antenna configuration will be used to investigate the effects of varying airborne SAR parameters such as depression angle, bandwidth, and integration angle, for various target types and deployment scenarios. Canonical targets data were used to evaluate overall facility capabilities and limitations. These data is analyzed and summarized for future evaluations. Finally, processing techniques for dealing with RF multi-path and RFI due to operating inside the indoor facility are described in detail. Discussion of this facility and its capabilities and limitations will provide the explosive hazard community with a great airborne platform asset for sensor to target assessment.

  9. FlexSAR, a high quality, flexible, cost effective, prototype SAR system

    NASA Astrophysics Data System (ADS)

    Jensen, Mark; Knight, Chad; Haslem, Brent

    2016-05-01

    The FlexSAR radar system was designed to be a high quality, low-cost, flexible research prototype instrument. Radar researchers and practitioners often desire the ability to prototype new or advanced configurations, yet the ability to enhance or upgrade existing radar systems can be cost prohibitive. FlexSAR answers the need for a flexible radar system that can be extended easily, with minimal cost and time expenditures. The design approach focuses on reducing the resources required for developing and validating new advanced radar modalities. Such an approach fosters innovation and provides risk reduction since actual radar data can be collected in the appropriate mode, processed, and analyzed early in the development process. This allows for an accurate, detailed understanding of the corresponding trade space. This paper is a follow-on to last years paper and discusses the advancements that have been made to the FlexSAR system. The overall system architecture is discussed and presented along with several examples illustrating the system utility.

  10. Radar observation of Venus' terrestrial analogues using TecSAR X-band SAR

    NASA Astrophysics Data System (ADS)

    Blumberg, D. G.

    2012-04-01

    Venus is shrouded in a dense CO2 atmosphere that prevents us from viewing the surface in visible light or with optronic sensors. Long wavelengths are required to 'see' through the dense atmosphere. In the early 1990s, the S-band synthetic aperture radar of the Magellan spacecraft acquired images of a variety of surface features on Venus, including morphologies attributed to wind processes. These include sand dunes, wind-sculpted hills (yardangs), and almost 6000 wind streaks. These aeolian landscapes were formed and shaped by near surface atmospheric circulation and local winds. These can serve as local markers, each providing an integrated wind direction. Since the Magellan mission, there were no missions to Venus until the Venus Express Mission of 2005 to examine the upper atmosphere. The future will probably include high-resolution SAR images of Venus. This poster will demonstrate high resolution SAR images in X-band from the TecSAR sensor launched by Israel in 2008. Observations of wind streaks, dunes and impact craters in desert areas will show the wealth of information that is extracted from high-res X-band data. Detailed images of Aurounga impact crater in Chad, Kelso dunes, California and Pisgah lava flow show immense detail of the morphologies associated with these features. These are compared with Magellan images of sites on Venus and SRL data in C and L-bands. The X-band provides extremely high resolution and resembles optical data much more than the longer wavelengths.

  11. FlexSAR, a high-quality, flexible, cost-effective, prototype SAR system

    NASA Astrophysics Data System (ADS)

    Jensen, Mark; Knight, Chad; Haslem, Brent

    2015-05-01

    The FlexSAR radar system was designed to be a high quality, low-cost, flexible prototype instrument. Many radar researchers and practitioners desire the ability to efficiently prototype novel configurations. However, the cost and time required to modify existing radar systems is a challenging hurdle that can be prohibitive. The FlexSAR system couples an RF design that leverages connectorized components with digital commercial-off-the-shelf (COTS) cards. This design allows for a scalable system that supports software defined radio (SDR) capabilities. This paper focuses on the RF and digital system design, discussing the advantages and disadvantages. The FlexSAR system design objective was to support diverse configurations with minimal non-recurring engineering (NRE) costs. Multiple diverse applications are examined, demonstrating the flexible system nature. The configurations discussed utilize different system parameters (e.g., number of phase-centers, transmit configurations, etc.). The resultant products are examined, illustrating that high-quality data products are still attained.

  12. Detection of Creep displacement along the North Anatolian Fault by ScanSAR-ScanSAR Interferometry

    NASA Astrophysics Data System (ADS)

    Deguchi, Tomonori

    North Anatolian Fault (NAF) has several records of a huge earthquake occurrence in the last one century, which is well-known as a risky active fault. Some signs indicating a creep displacement could be observed on the Ismetpasa segment. The fault with creep deformation is aseismic and never generates the large scale earthquakes. But the scale and rate of fault creep are important factors to watch the fault behavior and to understand the cycle of earthquake. The author had investigated the distribution of spatial and temporal change on the ground motion due to fault creep in the surrounding of the Ismetpasa by InSAR time series analysis using PALSAR datasets from 2007 until 2011. As a result, the land deformation that the northern and southern parts of the fault have slipped to east and west at a rate of 7.5 and 6.5 mm/year in line of sight respectively were obviously detected. These results had good agreement with GPS data. In addition, it became clear that the fault creep along the NAF extended 61 km in east to west direction. In this study, the author applied ScanSAR-ScanSAR Interferometry using PALSAR data to the Ismetpasa segment of NAF.

  13. Operational Quality Control of SAR Data under the IDEAS Contract

    NASA Astrophysics Data System (ADS)

    Griffiths, Emma; Haria, Kajal; Meadowws, Peter; Miranda, Nuno

    2010-12-01

    Operational Quality Control (QC) of ERS-1/2 Synthetic Aperture Radar (SAR), Envisat's Advanced Synthetic Aperture Radar (ASAR) and the Phased-Array L-band SAR (PALSAR) on board JAXA's Advanced Land Observing Satellite (ALOS) is currently carried out under the Image Data quality Evaluation and Analysis Service (IDEAS). This paper introduces the concept of IDEAS as it applies to SAR QC including the daily and long-term analysis and shows the interaces to related services, including ESA's user-facing Earth Observation (EO) Help Desk

  14. Derivation of terrain slope from SAR interferometric phase gradient

    NASA Technical Reports Server (NTRS)

    Wegmueller, Urs; Werner, Charles L.; Rosen, Paul A.

    1994-01-01

    The relationship between the gradient of the interferometric phase and the terrain slope, which, it is thought, would allow a derivation of the terrain slopes without phase unwrapping, is presented. A linear relationship between the interferometric phase gradient and the terrain slopes was found. A quantitative error analysis showed that only very small errors are introduced by these approximations for orbital Synthetic Aperture Radar (SAR) geometries. An example of a slope map for repeat pass interferometry from ERS-1 SAR data is given. A number of direct and indirect applications of the terrain slope are indicated: erosion and avalanche hazard studies, radiometric calibration of SAR data, and normalization of the interferometric correlation coefficient.

  15. SAR Reduction of PIFA with EBG Structures for Mobile Applications

    NASA Astrophysics Data System (ADS)

    Kwak, Sangil; Sim, Dong-Uk; Kwon, Jong Hwa; Yun, Je Hoon

    This paper proposes two types of electromagnetic bandgap (EBG) structures aimed for SAR reduction on a mobile phone antenna. The EBG structures, one which uses vias while the other does not can reduce the surface wave and prevent the undesired radiation from the antenna. Thus, these structures can reduce the electromagnetic fields toward the human head direction and reduction the SAR value. Tests demonstrate the reduction of SAR values and therefore, the human body can be protected from hazard electromagnetic fields by using the proposed EBG structures, regardless of whether vias are used or not.

  16. Mapping and monitoring renewable resources with space SAR

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.; Brisco, B.; Dobson, M. C.; Moezzi, S.

    1983-01-01

    The SEASAT-A SAR and SIR-A imagery was examined to evaluate the quality and type of information that can be extracted and used to monitor renewable resources on Earth. Two tasks were carried out: (1) a land cover classification study which utilized two sets of imagery acquired by the SEASAT-A SAR, one set by SIR-A, and one LANDSAT set (4 bands); and (2) a change detection to examine differences between pairs of SEASAT-A SAR images and relates them to hydrologic and/or agronomic variations in the scene.

  17. The potential of SAR directional spectra in operational wave forecasting

    NASA Technical Reports Server (NTRS)

    Beal, R. C.; Gerling, T. W.; Irvine, D. E.

    1983-01-01

    Digitally processed Seasat SAR ocean wave imagery, when digitally transformed, smoothed, and corrected for known instrument biases, can accurately track multiple (at least three) wave systems in the open ocean, across major currents, and into shallow water. Furthermore, the relative backscatterer of the digitally processed SAR image, when sampled within a single pass and along a constant range, responds to the local wind through a simple power law relationship. The results indicate that SAR spectra, if obtained from a low altitude satellite, could be an important supplement to global winds and non-directional wave heights obtained through other methods.

  18. SAR image effects on coherence and coherence estimation.

    SciTech Connect

    Bickel, Douglas Lloyd

    2014-01-01

    Radar coherence is an important concept for imaging radar systems such as synthetic aperture radar (SAR). This document quantifies some of the effects in SAR which modify the coherence. Although these effects can disrupt the coherence within a single SAR image, this report will focus on the coherence between separate images, such as for coherent change detection (CCD) processing. There have been other presentations on aspects of this material in the past. The intent of this report is to bring various issues that affect the coherence together in a single report to support radar engineers in making decisions about these matters.

  19. Use of SAR in Regional Methane Exchange Studies

    NASA Technical Reports Server (NTRS)

    Morrissey, L. A.; Livingston, G. P.; Durden, S. L.

    1994-01-01

    Significant sources of uncertainty in global trace gas budgets are due to lack of knowledge concerning the areal and temporal extent of source and sink areas. Synthetic aperture radar (SAR) is particularly suited to studies of northern ecosystems because of its all-weather operating capability which enables the acquisition of seasonal data. As key controls on methane exchange, the ability to differentiate major vegetation communities, inundation, and leaf area index (LAI) with satellite and airborne SAR data would increase the accuracy and precision of regional and seasonal estimates of methane exchange. The utility of SAR data for monitoring key controls on methane emissions from Arctic and boreal ecosystems is examined.

  20. Process for combining multiple passes of interferometric SAR data

    DOEpatents

    Bickel, Douglas L.; Yocky, David A.; Hensley, Jr., William H.

    2000-11-21

    Interferometric synthetic aperture radar (IFSAR) is a promising technology for a wide variety of military and civilian elevation modeling requirements. IFSAR extends traditional two dimensional SAR processing to three dimensions by utilizing the phase difference between two SAR images taken from different elevation positions to determine an angle of arrival for each pixel in the scene. This angle, together with the two-dimensional location information in the traditional SAR image, can be transformed into geographic coordinates if the position and motion parameters of the antennas are known accurately.

  1. Segmentation Of Multifrequency Complex-Amplitude SAR Data

    NASA Technical Reports Server (NTRS)

    Rignot, Eric J.; Chellappa, Ramalingam

    1994-01-01

    Several mathematical models and associated algorithms implement method of segmenting multifrequency, highly speckled, high-resolution, complex-amplitude (amplitude and phase) synthetic-aperture-radar (SAR) digitized image into regions, within each of which radar backscattering characteristics are similar or homogeneous from place to place. Typically, each region represents different type of terrain or other surface; e.g., forest, agricultural land, sea ice, or water. Method of segmentation of SAR scene into regions is product of generalization, to multifrequency case, of single-frequency method described in "Algorithms for Segmentation of Complex-Amplitude SAR Data" (NPO-18524).

  2. Alaska Synthetic Aperture Radar (SAR) Facility science data processing architecture

    NASA Technical Reports Server (NTRS)

    Hilland, Jeffrey E.; Bicknell, Thomas; Miller, Carol L.

    1991-01-01

    The paper describes the architecture of the Alaska SAR Facility (ASF) at Fairbanks, being developed to generate science data products for supporting research in sea ice motion, ice classification, sea-ice-ocean interaction, glacier behavior, ocean waves, and hydrological and geological study areas. Special attention is given to the individual substructures of the ASF: the Receiving Ground Station (RGS), the SAR Processor System, and the Interactive Image Analysis System. The SAR data will be linked to the RGS by the ESA ERS-1 and ERS-2, the Japanese ERS-1, and the Canadian Radarsat.

  3. Program Merges SAR Data on Terrain and Vegetation Heights

    NASA Technical Reports Server (NTRS)

    Siqueira, Paul; Hensley, Scott; Rodriguez, Ernesto; Simard, Marc

    2007-01-01

    X/P Merge is a computer program that estimates ground-surface elevations and vegetation heights from multiple sets of data acquired by the GeoSAR instrument [a terrain-mapping synthetic-aperture radar (SAR) system that operates in the X and bands]. X/P Merge software combines data from X- and P-band digital elevation models, SAR backscatter magnitudes, and interferometric correlation magnitudes into a simplified set of output topographical maps of ground-surface elevation and tree height.

  4. Deformation Monitoring of Urban Infrastructure by Tomographic SAR Using Multi-View TerraSAR-X Data Stacks

    NASA Astrophysics Data System (ADS)

    Montazeri, Sina; Zhu, Xiaoxiang; Eineder, Michael; Hanssen, Ramon F.; Bamler, Richard

    2015-05-01

    Synthetic Aperture Radar Tomography (TomoSAR) coupled with data from modern SAR sensors, such as the German TerraSAR-X (TS-X) produces the most detailed three-dimensional (3D) maps by distinguishing among multiple scatterers within a resolution cell. Furthermore, multi-temporal TomoSAR allows for recording the underlying deformation phenomenon of each individual scatterer. One of the limitations of using InSAR techniques, including TomoSAR, is that they only measure deformation along the radar Line-of-Sight (LOS). In order to enhance the understanding of deformation, a decomposition of the observed LOS displacement into the 3D deformation vector in the local coordinate system is desired. In this paper we propose a method, based on L1 norm minimization within local spatial cubes, to reconstruct 3D deformation vectors from TomoSAR point clouds available from, at least, three different viewing geometries. The methodology is applied on two pair of cross-heading TS-X spotlight image stacks over the city of Berlin. The linear deformation rate and amplitude of seasonal deformation are decomposed and the results from two individual test sites with remarkable deformation patterns are discussed in details.

  5. A tool for bistatic SAR geometry determinations

    NASA Astrophysics Data System (ADS)

    Hawkins, R. K.; Gibson, J. R.; Saper, R.; Hilaire, M.

    2003-12-01

    The geometry of wide-angle bistatic Synthetic Aperture Radar (SAR) is somewhat more complex than that of conventional Synthetic Aperture Radar because the transmitter and receiver are displaced considerably. Constant bistatic range surfaces form ellipsoids, with the transmitter and receiver located at the two foci. These ellipsoids of constant bistatic range intersect the earth's surface in a series of ellipse-like contours. Constant Doppler lines intersect the range ellipses and allow, under special circumstances, a simple orthogonal basis for processing and analysis. This paper introduces a simple tool, developed in MatLab® and C++, that uses RADARSAT-1 as a satellite illuminator and a tower-based receiver. Actual orbit parameters and data from RADARSAT-1 are used in the simulation of the bistatic geometry and scattering.

  6. SAR Agriculture Rice Production Estimation (SARPE)

    NASA Astrophysics Data System (ADS)

    Raimadoya, M.

    2013-12-01

    The study of SAR Agriculture Rice Production Estimation (SARPE) was held in Indonesia on 2012, as part of Asia-Rice Crop Estimation & Monitoring (Asia-RiCE), which is a component for the GEO Global Agricultural Monitoring (GEOGLAM) initiative. The study was expected to give a breakthrough result, by using radar technology and paradigm shift of the standard production estimation system from list frame to area frame approach. This initial product estimation system is expected to be refined (fine tuning) in 2013, by participating as part of Technical Demonstration Site (Phase -1A) of Asia-RICE. The implementation period of this initial study was from the date of March 12 to December 10, 2012. The implementation of the study was done by following the approach of the BIMAS-21 framework, which has been developed since 2008. The results of this study can be briefly divided into two major components, namely: Rice-field Baseline Mapping (PESBAK - Peta Sawah Baku) and Crop Growth Monitoring. Rice-fields were derived from the mapping results of the Ministry of Agriculture (Kemtan), and validated through Student Extension Campaign of the Faculty of Agriculture, Bogor Agricultural University (IPB). While for the crop growth, it was derived from the results of image analysis process. The analysis was done, either on radar/Radarsat-2 (medium resolution) or optical/ MODIS (low resolution), based on the Planting Calendar (KATAM) of Kemtan. In this case, the planting season II/2012-2013 of rice production centers in West Java Province (Karawang, Subang and Indramayu counties). The selection of crop season and county were entirely dependent on the quality of the available PESBAK and procurement process of radar imagery. The PESBAK is still in the form of block instead of fields, so it can not be directly utilized in this study. Efforts to improve the PESBAK can not be optimal because the provided satellite image (ECW format) is not the original one. While the procurement process of

  7. What have we learnt from SARS?

    PubMed Central

    Weiss, Robin A; McLean, Angela R

    2004-01-01

    With outbreaks of infectious disease emerging from animal sources, we have learnt to expect the unexpected. We were, and are, expecting a new influenza A pandemic, but no one predicted the emergence of an unknown coronavirus (CoV) as a deadly human pathogen. Thanks to the preparedness of the international network of influenza researchers and laboratories, the cause of severe acute respiratory syndrome (SARS) was rapidly identified, but there is no complacency over the global or local management of the epidemic in terms of public health logistics. The human population was lucky that only a small proportion of infected persons proved to be highly infectious to others, and that they did not become so before they felt ill. These were the features that helped to make the outbreak containable. The next outbreak of another kind of transmissible disease may well be quite different. PMID:15306402

  8. Technology for the ERS-1 SAR antenna

    NASA Astrophysics Data System (ADS)

    Wagner, R.

    1984-09-01

    The metallization of CFRP waveguides, the Deployable Truss Structure (DTS) and verification in terrestrial environment of the 10 x 1 m SAR antenna of ERS-1 (ESA satellite) are discussed. Waveguide metallization was achieved indirectly with metallization of the mandrel prior to CFRP lay-up, and directly, by electroplating of manufactured CFRP components. Both techniques proved unsatisfactory, but a surface treatment applied to the metal layer in the indirect technique improves adhesion strength by an order of magnitude, and enables the waveguides to meet requirements. The DTS satisfies launch, deployment, and inflight specifications for a 5 panel/2 wing structure. Ground tests include analytical simulation of deployment with and without gravity effects, and a gravity compensation technique for tests.

  9. Hybrid reduced graph for SAR studies.

    PubMed

    Carrasco-Velar, R; Prieto-Entenza, J O; Antelo-Collado, A; Padrón-García, J A; Cerruela-García, G; Maceo-Pixa, Á L; Alcolea-Núñez, R; Silva-Rojas, L G

    2013-01-01

    The purpose of this work is the definition and evaluation of both atomic and local new hybrid indices. Inspired by the Refractotopological State Index for Atoms, the new atomic indices are theoretically supported by graph theory principles. The local indices, named Descriptor Centres (DCs), are obtained from the sum of the atomic values of the atoms in the selected group. Different classifiers were used for structure-activity relationship (SAR) studies, including multilayer perceptron (MLP), support vector machines (SVM) and meta-classifiers. Prediction with SVM and MLP was around 60%, but the best result was obtained with the meta-classifiers, bagging, decorate and others, with more than 92% accurate prediction. These new hybrid descriptors derived from the Refractotopological State Index for Atoms show a low mutual correlation coefficient. The same behaviour is found in the analogously defined Descriptors Centres. The best results are obtained with the inclusion of the distance between DCs with the use of meta-classifiers. PMID:23439282

  10. SAR polar format implementation with MATLAB.

    SciTech Connect

    Martin, Grant D.; Doerry, Armin Walter

    2005-11-01

    Traditional polar format image formation for Synthetic Aperture Radar (SAR) requires a large amount of processing power and memory in order to accomplish in real-time. These requirements can thus eliminate the possible usage of interpreted language environments such as MATLAB. However, with trapezoidal aperture phase history collection and changes to the traditional polar format algorithm, certain optimizations make MATLAB a possible tool for image formation. Thus, this document's purpose is two-fold. The first outlines a change to the existing Polar Format MATLAB implementation utilizing the Chirp Z-Transform that improves performance and memory usage achieving near realtime results for smaller apertures. The second is the addition of two new possible image formation options that perform a more traditional interpolation style image formation. These options allow the continued exploration of possible interpolation methods for image formation and some preliminary results comparing image quality are given.

  11. CARABAS - an airborne VHF SAR system

    SciTech Connect

    Larsson, B.; Frolined, P.O.; Gustavsson, A.

    1996-11-01

    There is an increasing interest in imaging radar systems operating at low frequencies, Examples of civilian and military applications are detection of stealth-designed man-made objects, targets hidden under foliage, biomass estimation, and penetration into glaciers or ground. CARABAS (Coherent All Radio Band Sensing) is a new airborne SAR system developed by FOA. It is designed for operation in the lowest part of the VHF band (20-90 NHz), using horizontal polarisation. This frequency region gives the system a good ability to penetrate vegetation and to some extent ground. CARABAS is the first known SAR sensor with a capability of diffraction limited imaging, i.e. a resolution in magnitude of the adopted wavelengths. A Sabreliner business jet aircraft is used as the airborne platform. Critical parts in the development have been the antenna system, the receiver and the processing algorithms. Based upon the experiences gained with CARABAS I a major system upgrade is now taking place. The new CARABAS II system is scheduled to fly in May 1996. This system is designed to give operational performance while CARABAS I was used to verify the feasibility. The first major field campaigns are planned for the second half of 1996. CARABAS II is jointly developed by FOA and Ericsson Microwave Systems AB in Sweden. This paper will give an overview of the system design and data collected with the current radar system, including some results for forested regions. The achieved system performance will be discussed, with a presentation of the major modifications made in the new CARABAS 11 system. 12 refs., 7 figs., 2 tabs.

  12. Bats and emerging zoonoses: henipaviruses and SARS.

    PubMed

    Field, H E

    2009-08-01

    Nearly 75% of all emerging infectious diseases (EIDs) that impact or threaten human health are zoonotic. The majority have spilled from wildlife reservoirs, either directly to humans or via domestic animals. The emergence of many can be attributed to predisposing factors such as global travel, trade, agricultural expansion, deforestation/habitat fragmentation, and urbanization; such factors increase the interface and/or the rate of contact between human, domestic animal, and wildlife populations, thereby creating increased opportunities for spillover events to occur. Infectious disease emergence can be regarded as primarily an ecological process. The epidemiological investigation of EIDs associated with wildlife requires a trans-disciplinary approach that includes an understanding of the ecology of the wildlife species, and an understanding of human behaviours that increase risk of exposure. Investigations of the emergence of Nipah virus in Malaysia in 1999 and severe acute respiratory syndrome (SARS) in China in 2003 provide useful case studies. The emergence of Nipah virus was associated with the increased size and density of commercial pig farms and their encroachment into forested areas. The movement of pigs for sale and slaughter in turn led to the rapid spread of infection to southern peninsular Malaysia, where the high-density, largely urban pig populations facilitated transmission to humans. Identifying the factors associated with the emergence of SARS in southern China requires an understanding of the ecology of infection both in the natural reservoir and in secondary market reservoir species. A necessary extension of understanding the ecology of the reservoir is an understanding of the trade, and of the social and cultural context of wildlife consumption. Emerging infectious diseases originating from wildlife populations will continue to threaten public health. Mitigating and managing the risk requires an appreciation of the connectedness between human

  13. Two microstrip arrays for interferometric SAR applications

    NASA Technical Reports Server (NTRS)

    Huang, J.

    1993-01-01

    Two types of C-band aircraft interferometric Synthetic Aperture Radar (SAR) are being developed at JPL to measure the ocean wave characteristics. Each type requires two identical antennas with each having a long rectangular aperture to radiate fan-shaped beam(s). One type of these radars requires each of its antennas to radiate a broadside beam that will measure the target's cross-track velocity. The other type, having each of its antennas to radiate two off-broadside pointed beams, will allow the measurement of both the cross-track and the along-track velocities of the target. Because flush mounting of the antenna on the aircraft fuselage is desirable, microstrip patch array is selected for these interferometric SAR antennas. To meet the radar system requirement, each array needs a total of 76 microstrip patches which are arranged in a 38 x 2 rectangular aperture with a physical size of 1.6m x 16.5cm. To minimize the insertion loss and physical real estate of this relatively long array, a combined series/parallel feed technique is used. Techniques to suppress cross-pol radiation and to effectively utilize the RF power are also implemented. Cross-pol level of lower than -30 dB from the co-pol peak and low insertion loss of 0.36 dB have been achieved for both types of arrays. For the type of radar that requires two off-braodside pointed beams, a simple phasing technique is used to achieve this dual-beam capability with adequate antenna gain (20 dBi) and sidelobe level (-14 dB). Both radar arrays have been flight tested on aircraft with excellent antenna performance demonstrated.

  14. Analysing multitemporal SAR images for forest mapping

    NASA Astrophysics Data System (ADS)

    Maghsoudi, Yasser; Collins, Michael J.; Leckie, Donald G.

    2010-10-01

    The objective of this paper is twofold: first, to presents a generic approach for the analysis of Radarsat-1 multitemporal data and, second, to presents a multi classifier schema for the classification of multitemporal images. The general approach consists of preprocessing step and classification. In the preprocessing stage, the images are calibrated and registered and then temporally filtered. The resulted multitemporally filtered images are subsequently used as the input images in the classification step. The first step in a classifier design is to pick up the most informative features from a series of multitemporal SAR images. Most of the feature selection algorithms seek only one set of features that distinguish among all the classes simultaneously and hence a limited amount of classification accuracy. In this paper, a class-based feature selection (CBFS) was proposed. In this schema, instead of using feature selection for the whole classes, the features are selected for each class separately. The selection is based on the calculation of JM distance of each class from the rest of classes. Afterwards, a maximum likelihood classifier is trained on each of the selected feature subsets. Finally, the outputs of the classifiers are combined through a combination mechanism. Experiments are performed on a set of 34 Radarsat-1 images acquired from August 1996 to February 2007. A set of 9 classes in a forest area are used in this study. Classification results confirm the effectiveness of the proposed approach compared with the case of single feature selection. Moreover, the proposed process is generic and hence is applicable in different mapping purposes for which a multitemporal set of SAR images are available.

  15. 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.

  16. Decreasing range resolution of a SAR image to permit correction of motion measurement errors beyond the SAR range resolution

    SciTech Connect

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

    2010-07-20

    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.

  17. The Grand Banks ERS-1 SAR wave spectra validation experiment

    NASA Technical Reports Server (NTRS)

    Vachon, P. W.; Dobson, F. W.; Smith, S. D.; Anderson, R. J.; Buckley, J. R.; Allingham, M.; Vandemark, D.; Walsh, E. J.; Khandekar, M.; Lalbeharry, R.

    1993-01-01

    As part of the ERS-1 validation program, the ERS-1 Synthetic Aperture Radar (SAR) wave spectra validation experiment was carried out over the Grand Banks of Newfoundland (Canada) in Nov. 1991. The principal objective of the experiment was to obtain complete sets of wind and wave data from a variety of calibrated instruments to validate SAR measurements of ocean wave spectra. The field program activities are described and the rather complex wind and wave conditions which were observed are summarized. Spectral comparisons with ERS-1 SAR image spectra are provided. The ERS-1 SAR is shown to have measured swell and range traveling wind seas, but did not measure azimuth traveling wind seas at any time during the experiment. Results of velocity bunching forward mapping and new measurements of the relationship between wind stress and sea state are also shown.

  18. a Rail Central Displacement Method about Gb-Sar

    NASA Astrophysics Data System (ADS)

    Peng, J.; Cai, J.; Yang, H.

    2016-06-01

    This paper presents a new method to correct rail errors of Ground Based Synthetic Aperture Radar (GB-SAR) in the discontinue mode. Generally, "light positioning" is performed to mark the GB-SAR position in the dis-continuous observation mode. Usually we assume there is no difference between the marked position and the real installation position. But in fact, it is hard to keep the GB-SAR positions of two campaigns the same, so repositioning errors can't be neglected. In order to solve this problem, we propose an algorithm to correct the rail error after analyzing the GB-SAR rail error geometry. Results of the simulation experiment and the real experiment of a landslide in Lvliang, Shanxi, China, show the proposed method achieves an mm-level precision, enabling the D-GBSAR mode to be used in engineering projects.

  19. SAR imaging technique for reduction of sidelobes and noise

    NASA Astrophysics Data System (ADS)

    Nguyen, Lam

    2009-05-01

    Multiplicative noise poses a big challenge for SAR imaging system, in which energy from the sidelobes of large RCS man-made and natural clutter objects spread throughout the resulting SAR imagery. Detection of small RCS targets is very difficult since their signatures might be obscured or even embedded in this multiplicative noise floor that is proportional to the RCS of surrounding clutter objects. ARL has developed a Recursive Sidelobe Minimization (RSM) technique that is combined with the standard backprojection image formation algorithm to suppress the multiplicative noise floor in the resulting SAR imagery. In this paper, we present the Recursive Sidelobe Minimization (RSM) technique. Although the technique is originally developed and tested using data from the Army Research Lab (ARL) UWB Synchronous Impulse Reconstruction (SIRE) forward-looking radar, it is also applicable for other SAR data sets with different configurations.

  20. Copernicus Sentinel-1 Satellite And C-SAR Instrument

    NASA Astrophysics Data System (ADS)

    Panetti, Aniceto; Rostan, Friedhelm; L'Abbate, Michelangelo; Bruno, Claudio; Bauleo, Antonio; Catalano, Toni; Cotogni, Marco; Galvagni, Luigi; Pietropaolo, Andrea; Taini, Giacomo; Venditti, Paolo; Huchler, Markus; Torres, Ramon; Lokaas, Svein; Bibby, David

    2013-12-01

    The Copernicus Sentinel-1 Earth Radar Observatory, a mission funded by the European Union and developed by ESA, is a constellation of two C-band radar satellites. The satellites have been conceived to be a continuous and reliable source of C-band SAR imagery for operational applications such as mapping of global landmasses, coastal zones and monitoring of shipping routes. The Sentinel-1 satellites are built by an industrial consortium led by Thales Alenia Space Italia as Prime Contractor and with Astrium GmbH as SAR Instrument Contractor. The paper describes the general satellite architecture, the spacecraft subsystems, AIT flow and the satellite key performances. It provides also an overview on the C-SAR Instrument, its development status and pre- launch SAR performance prediction.

  1. Range stacking: an interpolation-free SAR reconstruction algorithm

    NASA Astrophysics Data System (ADS)

    Soumekh, Mehrdad

    1998-09-01

    A method for digital image formation in Synthetic Aperture Radar (SAR) systems is presented. The proposed approach is based on the wavefront reconstruction theory for SAR imaging systems. However, this is achieved without image formation in the spatial frequency domain of the target function which requires interpolation. The proposed method forms the target function at individual range points within the radar range swath; this is referred to as range stacking. The range stacking reconstruction method is applicable in stripmap and spotlight (broadside and squint) SAR systems. Results using a wide-beamwidth FOliage PENetrating (FOPEN) SAR database are provided, and the effect of beamwidth filtering on the signature of moving targets in the imaging scene is shown.

  2. Target surface finding using 3D SAR data

    NASA Astrophysics Data System (ADS)

    Ruiter, Jason R.; Burns, Joseph W.; Subotic, Nikola S.

    2005-05-01

    Methods of generating more literal, easily interpretable imagery from 3-D SAR data are being studied to provide all weather, near-visual target identification and/or scene interpretation. One method of approaching this problem is to automatically generate shape-based geometric renderings from the SAR data. In this paper we describe the application of the Marching Tetrahedrons surface finding algorithm to 3-D SAR data. The Marching Tetrahedrons algorithm finds a surface through the 3-D data cube, which provides a recognizable representation of the target surface. This algorithm was applied to the public-release X-patch simulations of a backhoe, which provided densely sampled 3-D SAR data sets. The performance of the algorithm to noise and spatial resolution were explored. Surface renderings were readily recognizable over a range of spatial resolution, and maintained their fidelity even under relatively low Signal-to-Noise Ratio (SNR) conditions.

  3. [Simulation of polarization SAR imaging of ocean surface].

    PubMed

    Guo, Ding; Gu, Xing-Fa; Yu, Tao; Fernado, N; Li, Juan; Chen, Xing-Feng

    2011-10-01

    The polarization synthetic aperture radar (SAR) imaging simulation is of great significance to ocean surface scattering. According to the theory of wind-wave spectrum, rough ocean surface was modeled in the present paper using the two-scale-model. This treatment takes both the large scale and small scale surface into account. By using the velocity bunching (VB) theory, Bragg scattering model and the small perturbation model (SPM), the polarization SAR system can simulate the ocean surface with various parameters and ocean states. The effects of the parameters of ocean waves and the parameters of SAR system were analyzed. Finally, some useful conclusions were drawn, which are helpful for extracting the information of ocean surface. The method is an effective way in the ocean SAR design and the ocean surface research. PMID:22250525

  4. Modeling of SAR signatures of shallow water ocean topography

    NASA Technical Reports Server (NTRS)

    Shuchman, R. A.; Kozma, A.; Kasischke, E. S.; Lyzenga, D. R.

    1984-01-01

    A hydrodynamic/electromagnetic model was developed to explain and quantify the relationship between the SEASAT synthetic aperture radar (SAR) observed signatures and the bottom topography of the ocean in the English Channel region of the North Sea. The model uses environmental data and radar system parameters as inputs and predicts SAR-observed backscatter changes over topographic changes in the ocean floor. The model results compare favorably with the actual SEASAT SAR observed backscatter values. The developed model is valid for only relatively shallow water areas (i.e., less than 50 meters in depth) and suggests that for bottom features to be visible on SAR imagery, a moderate to high velocity current and a moderate wind must be present.

  5. Diverse deformation patterns of Aleutian volcanoes from InSAR

    USGS Publications Warehouse

    Lu, Zhiming; Dzurisin, D.; Wicks, C., Jr.; Power, J.

    2008-01-01

    Interferometric synthetic aperture radar (InSAR) is capable of measuring ground-surface deformation with centimeter-to-subcentimeter precision at a spatial resolution of tens of meters over an area of hundreds to thousands of square kilometers. With its global coverage and all-weather imaging capability, InSAR has become an increasingly important measurement technique for constraining magma dynamics of volcanoes over remote regions such as the Aleutian Islands. The spatial pattern of surface deformation data derived from InSAR images enables the construction of detailed mechanical models to enhance the study of magmatic processes. This paper summarizes the diverse deformation patterns of the Aleutian volcanoes observed with InSAR and demonstrates that deformation patterns and associated magma supply mechanisms in the Aleutians are diverse and vary between volcanoes. These findings provide a basis for improved models and better understanding of magmatic plumbing systems.

  6. THE PRACTICE OF STRUCTURE ACTIVITY RELATIONSHIPS (SAR) IN TOXICOLOGY

    EPA Science Inventory

    Both qualitative and quantitative modeling methods relating chemical structure to biological activity, called structure-activity relationship analyses or SAR, are applied to the prediction and characterization of chemical toxicity. This minireview will discuss some generic issue...

  7. An analysis of Seasat SAR for detecting geologic linears

    NASA Technical Reports Server (NTRS)

    Yan, S.-Y.; Philipson, W. R.; Teng, W. L.

    1982-01-01

    The value of Seasat synthetic aperture radar (SAR) imagery for detecting geologic linears was assessed in a study of an 89,000 sq km section of New York's Adirondack Mountains. A photographic print of optically processed, 1:500,000 scale SAR imagery (one look direction) was analyzed visually, and the detected linears were compared to those recorded on a 1:250,000 scale geologic map. Eighty percent of the 4,170 km of mapped, geologic linears were detected with the SAR imagery. Moreover, nearly 6,900 km of unmapped linears were also detected. Of these, an estimated 90 percent could be observed on high altitude aerial photographs. The relationship between SAR image detection of linears and the different types of indicators (e.g., straight valleys or shorelines) is reported.

  8. A comparative study of SAR data compression schemes

    NASA Technical Reports Server (NTRS)

    Lambert-Nebout, C.; Besson, O.; Massonnet, D.; Rogron, B.

    1994-01-01

    The amount of data collected from spaceborne remote sensing has substantially increased in the last years. During same time period, the ability to store or transmit data has not increased as quickly. At this time, there is a growing interest in developing compression schemes that could provide both higher compression ratios and lower encoding/decoding errors. In the case of the spaceborne Synthetic Aperture Radar (SAR) earth observation system developed by the French Space Agency (CNES), the volume of data to be processed will exceed both the on-board storage capacities and the telecommunication link. The objective of this paper is twofold: to present various compression schemes adapted to SAR data; and to define a set of evaluation criteria and compare the algorithms on SAR data. In this paper, we review two classical methods of SAR data compression and propose novel approaches based on Fourier Transforms and spectrum coding.

  9. 3. DETAIL, LIGHTNING ARRESTER ON SAR TRANSMISSION LINE. EEC print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. DETAIL, LIGHTNING ARRESTER ON SAR TRANSMISSION LINE. EEC print no. S-C-01-00478, no date. Photographer unknown. - Santa Ana River Hydroelectric System, Transmission Lines, Redlands, San Bernardino County, CA

  10. Ionospheric composition in SAR-arcs. [Stable Auroral Red Arcs

    NASA Technical Reports Server (NTRS)

    Raitt, W. J.; Schunk, R. W.; Banks, P. M.

    1976-01-01

    Theoretical ion and electron density profiles in the SAR-arc region are calculated using a model of the ionosphere based on the coupled continuity, momentum, and energy equations for O(+), NO(+), and O2(+). It is found that an increase in the reaction O(+) + N2 yields NO(+) + N, which results from enhanced N2 vibrational excitation due to the high electron temperatures found in SAR arcs, can cause a reduction in F-region electron densities by up to a factor of two. The increase in the O(+) + N2 reaction rate is shown to result in a marked change in the ion composition in SAR arcs, with NO(+) being an important ion up to altitudes of about 350 km at night. Since observed electron-density depressions in SAR arcs generally vary between factors of two and seven, it is concluded that the increase in the O(+) + N2 reaction rate cannot account for these depressions by itself.

  11. Characteristics of merchant vessels in spaceborne SAR imagery

    NASA Astrophysics Data System (ADS)

    Chen, Peng; Huang, Weigen; Yang, Jingsong; Fu, Bin; Lou, XiuLin; Zhang, Huagon

    2006-12-01

    Ship features in high-resolution spaceborne Synthetic Aperture Radar (SAR) imagery has crucial significance for ship classification from satellite. In this paper, we discuss the features of merchant Ships including oil tanker, container ship and bulk carrier in SAR imagery, which is comprised of geometrical feature, scattering feature, tonnage information with Radar Cross Section (RCS) and wake. The study show that the ship lengths measured from SAR imagery has a good correlation with the real lengths, but the correlation of ship beam is worse. Ship scattering feature has positive correlation with the ship structure, which maybe is a feature to distinguish container ship from other vessels. A new equation about ship length and its displacement in tons is presented in this paper. The relation suggested by Skolnik M.I between ship tonnage and RCS is tested but not validated. We also validate the means of extracting ship speed by ship turbulence wake in SAR imagery.

  12. A beamforming algorithm for bistatic SAR image formation.

    SciTech Connect

    Yocky, David Alan; Wahl, Daniel Eugene; Jakowatz, Charles V., Jr.

    2010-03-01

    Beamforming is a methodology for collection-mode-independent SAR image formation. It is essentially equivalent to backprojection. The authors have in previous papers developed this idea and discussed the advantages and disadvantages of the approach to monostatic SAR image formation vis--vis the more standard and time-tested polar formatting algorithm (PFA). In this paper we show that beamforming for bistatic SAR imaging leads again to a very simple image formation algorithm that requires a minimal number of lines of code and that allows the image to be directly formed onto a three-dimensional surface model, thus automatically creating an orthorectified image. The same disadvantage of beamforming applied to monostatic SAR imaging applies to the bistatic case, however, in that the execution time for the beamforming algorithm is quite long compared to that of PFA. Fast versions of beamforming do exist to help alleviate this issue. Results of image reconstructions from phase history data are presented.

  13. Nonuniform FFTs (NUFFT) algorithms applied to SAR imaging

    NASA Astrophysics Data System (ADS)

    Subiza, Begona; Gimeno-Nieves, Encarna; Lopez-Sanchez, Juan M.; Fortuny-Guasch, Joaquim

    2004-01-01

    Some recently developed algorithms known as Non-Uniform FFT's (NUFFT), which enable the computation of efficient FFT's with unequally spaced data in the time or frequency domain, have been applied to SAR imaging in this study. The main objective has been to analyze the potential improvement of the computational efficiency and/or image accuracy of seismic migration SAR processing techniques, like the ω-k algorithm. Our approach consists in substituting both the Stolt interpolation and the final range inverse FFT by a single NUFFT. Numerical simulations illustrate the performance of the new method and the influence of the selection of NUFFT parameters in the precision and computation time of the SAR imaging algorithm. The new method is especially suited for near-field wide-band configurations, such as inverse SAR (ISAR) and ground-based systems, where a very precise imaging algorithm is required.

  14. Alaska SAR processor implementation of E-ERS-1

    NASA Technical Reports Server (NTRS)

    Cuddy, David; Chen, Ming-Je; Bicknell, Tom

    1992-01-01

    The synthetic aperture radar (SAR) data processing algorithm used by the Alaska SAR Facility (ASF) for the European Space Agency's first Remote-Sensing Satellite (E-ERS-1) SAR data are examined. Preprocessing highlights two features: signal measurement, which includes signal-to-noise ratio, replica measurement, and noise measurement; and Doppler measurement, which includes clutter lock and autofocus. The custom pipeline architecture performs the main processing with controls at the input interface, range correlator, corner-turn memory, azimuth correlator, and multi-look memory. The control software employs a flexible control scheme. The Committee on Earth Observation Satellites (CEOS) format encapsulates the ASF products. System performance for SAR image processing of E-ERS-1 data is reviewed.

  15. 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.

  16. The Staphylococcus aureus Protein-Coding Gene gdpS Modulates sarS Expression via mRNA-mRNA Interaction

    PubMed Central

    Chen, Chuan; Zhang, Xu; Shang, Fei; Sun, Haipeng

    2015-01-01

    Staphylococcus aureus is an important Gram-positive pathogen responsible for numerous diseases ranging from localized skin infections to life-threatening systemic infections. The virulence of S. aureus is essentially determined by a wide spectrum of factors, including cell wall-associated proteins and secreted toxins that are precisely controlled in response to environmental changes. GGDEF domain protein from Staphylococcus (GdpS) is the only conserved staphylococcal GGDEF domain protein that is involved not in c-di-GMP synthesis but in the virulence regulation of S. aureus NCTC8325. Our previous study showed that the inactivation of gdpS generates an extensive change of virulence factors together with, in particular, a major Spa (protein A) surface protein. As reported, sarS is a direct positive regulator of spa. The decreased transcript levels of sarS in the gdpS mutant compared with the parental NCTC8325 strain suggest that gdpS affects spa through interaction with sarS. In this study, site mutation and complementary experiments showed that the translation product of gdpS was not involved in the regulation of transcript levels of sarS. We found that gdpS functioned through direct RNA-RNA base pairing with the 5′ untranslated region (5′UTR) of sarS mRNA and that a putative 18-nucleotide region played a significant role in the regulatory process. Furthermore, the mRNA half-life analysis of sarS in the gdpS mutant showed that gdpS positively regulates the mRNA levels of sarS by contributing to the stabilization of sarS mRNA, suggesting that gdpS mRNA may regulate spa expression in an RNA-dependent pathway. PMID:26056387

  17. A SAR ATR algorithm based on coherent change detection

    SciTech Connect

    Harmony, D.W.

    2000-12-01

    This report discusses an automatic target recognition (ATR) algorithm for synthetic aperture radar (SAR) imagery that is based on coherent change detection techniques. The algorithm relies on templates created from training data to identify targets. Objects are identified or rejected as targets by comparing their SAR signatures with templates using the same complex correlation scheme developed for coherent change detection. Preliminary results are presented in addition to future recommendations.

  18. Using airborne and satellite SAR for wake mapping offshore

    NASA Astrophysics Data System (ADS)

    Christiansen, Merete B.; Hasager, Charlotte B.

    2006-09-01

    Offshore wind energy is progressing rapidly around Europe. One of the latest initiatives is the installation of multiple wind farms in clusters to share cables and maintenance costs and to fully exploit premium wind resource sites. For siting of multiple nearby wind farms, the wind turbine wake effect must be considered. Synthetic aperture radar (SAR) is an imaging remote sensing technique which offers a unique opportunity to describe spatial variations of wind speed offshore. For the first time an airborne SAR instrument was used for data acquisition over a large offshore wind farm. The aim was to identify the turbine wake effect from SAR-derived wind speed maps as a downstream region of reduced wind speed. The aircraft SAR campaign was conducted on 12 October 2003 over the wind farm at Horns Rev in the North Sea. Nearly simultaneous measurements were acquired over the area by the SAR on board the ERS-2 satellite. In addition, meteorological data were collected. Both aircraft and satellite SAR-derived wind speed maps showed significant velocity deficits downstream of the wind farm. Wind speed maps retrieved from aircraft SAR suggested deficits of up to 20% downstream of the last turbine, whereas satellite SAR-derived maps showed deficits of the order of 10%. The difference originated partly from the two different reference methods used for normalization of measured wind speeds. The detected region of reduced wind speed had the same width as the wind turbine array, indicating a low degree of horizontal wake dispersion. The downstream wake extent was approximately 10 km, which corresponds well with results from previous studies and with wake model predictions. Copyright

  19. SAR terrain classifier and mapper of biophysical attributes

    NASA Technical Reports Server (NTRS)

    Ulaby, Fawwaz T.; Dobson, M. Craig; Pierce, Leland; Sarabandi, Kamal

    1993-01-01

    In preparation for the launch of SIR-C/X-SAR and design studies for future orbital SAR, a program has made considerable progress in the development of an SAR terrain classifier and algorithms for quantification of biophysical attributes. The goal of this program is to produce a generalized software package for terrain classification and estimation of biophysical attributes and to make this package available to the larger scientific community. The basic elements of the SAR (Synthetic Aperture Radar) terrain classifier are outlined. An SAR image is calibrated with respect to known system and processor gains and external targets (if available). A Level 1 classifier operates on the data to differentiate: urban features, surfaces and tall and short vegetation. Level 2 classifiers further subdivide these classes on the basis of structure. Finally, biophysical and geophysical inversions are applied to each class to estimate attributes of interest. The process used to develop the classifiers and inversions is shown. Radar scattering models developed from theory and from empirical data obtained by truck-mounted polarimeters and the JPL AirSAR are validated. The validated models are used in sensitivity studies to understand the roles of various scattering sources (i.e., surface trunk, branches, etc.) in determining net backscatter. Model simulations of sigma (sup o) as functions of the wave parameters (lambda, polarization and angle of incidence) and the geophysical and biophysical attributes are used to develop robust classifiers. The classifiers are validated using available AirSAR data sets. Specific estimators are developed for each class on the basis of the scattering models and empirical data sets. The candidate algorithms are tested with the AirSAR data sets. The attributes of interest include: total above ground biomass, woody biomass, soil moisture and soil roughness.

  20. SARAS - A synthetic aperture radar (SAR) raw signal simulator

    NASA Astrophysics Data System (ADS)

    Franceschetti, Giorgio; Migliaccio, Maurizio; Riccio, Daniele; Schirinzi, Gilda

    1992-01-01

    An SAR simulator of an extended three-dimensional scene is presented. It is based on a fact model for the scene, asymptotic evaluation of SAR unit response, and two-dimensional fast Fourier transform (FFT) code for data processing. Prescribed statistics of the model account for a realistic speckle of the image. The simulator is implemented in SARAS, whose performance is described and illustrated by a number of examples.

  1. Archived 1976-1985 JPL Aircraft SAR Data

    NASA Technical Reports Server (NTRS)

    Thompson, Thomas W.; Blom, Ronald G.

    2016-01-01

    This report describes archived data from the Jet Propulsion Laboratory (JPL) aircraft radar expeditions in the mid-1970s through the mid-1980s collected by Ron Blom, JPL Radar Geologist. The dataset was collected during Ron's career at JPL from the 1970s through 2015. Synthetic Aperture Radar (SAR) data in the 1970s and 1980s were recorded optically on long strips of film. SAR imagery was produced via an optical, holographic technique that resulted in long strips of film imagery.

  2. One carbon metabolism in SAR11 pelagic marine bacteria.

    PubMed

    Sun, Jing; Steindler, Laura; Thrash, J Cameron; Halsey, Kimberly H; Smith, Daniel P; Carter, Amy E; Landry, Zachary C; Giovannoni, Stephen J

    2011-01-01

    The SAR11 Alphaproteobacteria are the most abundant heterotrophs in the oceans and are believed to play a major role in mineralizing marine dissolved organic carbon. Their genomes are among the smallest known for free-living heterotrophic cells, raising questions about how they successfully utilize complex organic matter with a limited metabolic repertoire. Here we show that conserved genes in SAR11 subgroup Ia (Candidatus Pelagibacter ubique) genomes encode pathways for the oxidation of a variety of one-carbon compounds and methyl functional groups from methylated compounds. These pathways were predicted to produce energy by tetrahydrofolate (THF)-mediated oxidation, but not to support the net assimilation of biomass from C1 compounds. Measurements of cellular ATP content and the oxidation of (14)C-labeled compounds to (14)CO(2) indicated that methanol, formaldehyde, methylamine, and methyl groups from glycine betaine (GBT), trimethylamine (TMA), trimethylamine N-oxide (TMAO), and dimethylsulfoniopropionate (DMSP) were oxidized by axenic cultures of the SAR11 strain Ca. P. ubique HTCC1062. Analyses of metagenomic data showed that genes for C1 metabolism occur at a high frequency in natural SAR11 populations. In short term incubations, natural communities of Sargasso Sea microbial plankton expressed a potential for the oxidation of (14)C-labeled formate, formaldehyde, methanol and TMAO that was similar to cultured SAR11 cells and, like cultured SAR11 cells, incorporated a much larger percentage of pyruvate and glucose (27-35%) than of C1 compounds (2-6%) into biomass. Collectively, these genomic, cellular and environmental data show a surprising capacity for demethylation and C1 oxidation in SAR11 cultures and in natural microbial communities dominated by SAR11, and support the conclusion that C1 oxidation might be a significant conduit by which dissolved organic carbon is recycled to CO(2) in the upper ocean. PMID:21886845

  3. Statistical Approach To Extraction Of Texture In SAR

    NASA Technical Reports Server (NTRS)

    Rignot, Eric J.; Kwok, Ronald

    1992-01-01

    Improved statistical method of extraction of textural features in synthetic-aperture-radar (SAR) images takes account of effects of scheme used to sample raw SAR data, system noise, resolution of radar equipment, and speckle. Treatment of speckle incorporated into overall statistical treatment of speckle, system noise, and natural variations in texture. One computes speckle auto-correlation function from system transfer function that expresses effect of radar aperature and incorporates range and azimuth resolutions.

  4. Initial viral load and the outcomes of SARS

    PubMed Central

    Chu, Chung-Ming; Poon, Leo L.M.; Cheng, Vincent C.C.; Chan, Kin-Sang; Hung, Ivan F.N.; Wong, Maureen M.L.; Chan, Kwok-Hung; Leung, Wah-Shing; Tang, Bone S.F.; Chan, Veronica L.; Ng, Woon-Leung; Sim, Tiong-Chee; Ng, Ping-Wing; Law, Kin-Ip; Tse, Doris M.W.; Peiris, Joseph S.M.; Yuen, Kwok-Yung

    2004-01-01

    Background Severe acute respiratory syndrome (SARS) is caused by a novel coronavirus. It may progress to respiratory failure, and a significant proportion of patients die. Preliminary data suggest that a high viral load of the SARS coronavirus is associated with adverse outcomes in the intensive care unit, but the relation of viral load to survival is unclear. Methods We prospectively studied an inception cohort of 133 patients with virologically confirmed SARS who were admitted to 2 general acute care hospitals in Hong Kong from Mar. 24 to May 4, 2003. The patients were followed until death or for a minimum of 90 days. We used Cox proportional hazard modelling to analyze potential predictors of survival recorded at the time of presentation, including viral load from nasopharyngeal specimens (measured by quantitative reverse transcriptase polymerase chain reaction [PCR] of the SARS-associated coronavirus). Results Thirty-two patients (24.1%) met the criteria for acute respiratory distress syndrome, and 24 patients (18.0%) died. The following baseline factors were independently associated with worse survival: older age (61–80 years) (adjusted hazard ratio [HR] 5.24, 95% confidence interval [CI] 2.03–13.53), presence of an active comorbid condition (adjusted HR 3.36, 95% CI 1.44–7.82) and higher initial viral load of SARS coronavirus, according to quantitative PCR of nasopharyngeal specimens (adjusted HR 1.21 per log10 increase in number of RNA copies per millilitre, 95% CI 1.06–1.39). Interpretation We found preliminary evidence that higher initial viral load is independently associated with worse prognosis in SARS. Mortality data for patients with SARS should be interpreted in light of age, comorbidity and viral load. These considerations will be important in future studies of SARS. PMID:15557587

  5. Taiga forest stands and SAR: Monitoring for subarctic global change

    SciTech Connect

    Way, J.; Kwok, R.; Viereck, L.; Slaughter, C.; Dobson, C.

    1992-03-01

    In preparation for the first European Earth Remote Sensing (ERS-1) mission, a series of multitemporal, multifrequency, multipolarization aircraft synthetic aperture radar (SAR) data sets were acquired over the Bonanza Creek Experimental Forest near Fairbanks, Alaska in March 1988. Significant change in radar backscatter was observed over the two-week experimental period due to changing environmental conditions. These preliminary results are presented to illustrate the opportunity afforded by the ERS-1 SAR to monitor temporal change in forest ecosystems.

  6. SAR image formation with azimuth interpolation after azimuth transform

    SciTech Connect

    Doerry; Armin W. , Martin; Grant D. , Holzrichter; Michael W.

    2008-07-08

    Two-dimensional SAR data can be processed into a rectangular grid format by subjecting the SAR data to a Fourier transform operation, and thereafter to a corresponding interpolation operation. Because the interpolation operation follows the Fourier transform operation, the interpolation operation can be simplified, and the effect of interpolation errors can be diminished. This provides for the possibility of both reducing the re-grid processing time, and improving the image quality.

  7. Nano(Q)SAR: Challenges, pitfalls and perspectives.

    PubMed

    Tantra, Ratna; Oksel, Ceyda; Puzyn, Tomasz; Wang, Jian; Robinson, Kenneth N; Wang, Xue Z; Ma, Cai Y; Wilkins, Terry

    2015-01-01

    Regulation for nanomaterials is urgently needed, and the drive to adopt an intelligent testing strategy is evident. Such a strategy will not only provide economic benefits but will also reduce moral and ethical concerns arising from animal testing. For regulatory purposes, such an approach is promoted by REACH, particularly the use of quantitative structure-activity relationships [(Q)SAR] as a tool for the categorisation of compounds according to their physicochemical and toxicological properties. In addition to compounds, (Q)SAR has also been applied to nanomaterials in the form of nano(Q)SAR. Although (Q)SAR in chemicals is well established, nano(Q)SAR is still in early stages of development and its successful uptake is far from reality. This article aims to identify some of the pitfalls and challenges associated with nano-(Q)SARs in relation to the categorisation of nanomaterials. Our findings show clear gaps in the research framework that must be addressed if we are to have reliable predictions from such models. Three major barriers were identified: the need to improve quality of experimental data in which the models are developed from, the need to have practical guidelines for the development of the nano(Q)SAR models and the need to standardise and harmonise activities for the purpose of regulation. Of these three, the first, i.e. the need to improve data quality requires immediate attention, as it underpins activities associated with the latter two. It should be noted that the usefulness of data in the context of nano-(Q)SAR modelling is not only about the quantity of data but also about the quality, consistency and accessibility of those data. PMID:25211549

  8. SAR11 bacteria linked to ocean anoxia and nitrogen loss.

    PubMed

    Tsementzi, Despina; Wu, Jieying; Deutsch, Samuel; Nath, Sangeeta; Rodriguez-R, Luis M; Burns, Andrew S; Ranjan, Piyush; Sarode, Neha; Malmstrom, Rex R; Padilla, Cory C; Stone, Benjamin K; Bristow, Laura A; Larsen, Morten; Glass, Jennifer B; Thamdrup, Bo; Woyke, Tanja; Konstantinidis, Konstantinos T; Stewart, Frank J

    2016-08-11

    Bacteria of the SAR11 clade constitute up to one half of all microbial cells in the oxygen-rich surface ocean. SAR11 bacteria are also abundant in oxygen minimum zones (OMZs), where oxygen falls below detection and anaerobic microbes have vital roles in converting bioavailable nitrogen to N2 gas. Anaerobic metabolism has not yet been observed in SAR11, and it remains unknown how these bacteria contribute to OMZ biogeochemical cycling. Here, genomic analysis of single cells from the world's largest OMZ revealed previously uncharacterized SAR11 lineages with adaptations for life without oxygen, including genes for respiratory nitrate reductases (Nar). SAR11 nar genes were experimentally verified to encode proteins catalysing the nitrite-producing first step of denitrification and constituted ~40% of OMZ nar transcripts, with transcription peaking in the anoxic zone of maximum nitrate reduction activity. These results link SAR11 to pathways of ocean nitrogen loss, redefining the ecological niche of Earth's most abundant organismal group. PMID:27487207

  9. Forest stand structure from airborne polarimetric InSAR

    NASA Astrophysics Data System (ADS)

    Balzter, H.; Saich, P.; Luckman, A. J.; Skinner, L.; Grant, J.

    2002-01-01

    Interferometric SAR at short wavelengths can be used to retrieve stand height of forests. We evaluate the precision of tree height estimation from airborne single-pass interferometric E-SAR data at X-band VV polarisation and repeat-pass L-band polarimetric data. General yield class curves were used to estimate tree height from planting year, tree species and yield class data provided by the Forest Enterprise. The data were compared to tree height estimates from X-VV single-pass InSAR and repeat-pass polarimetric InSAR at L-band acquired by DLR's E-SAR during the SHAC campaign 2000. The effect of gap structure and incidence angle on retrieval precision of tree height from interferometric SAR is analysed. Appropriate correction methods to improve tree height retrieval are proposed. The coherent microwave model CASM is used with a Lindenmayer system tree model to simulate the observed underestimation of stand height in the presence of gaps.

  10. (abstract) The EOS SAR Mission: A New Approach

    NASA Technical Reports Server (NTRS)

    Way, JoBea

    1993-01-01

    The goal of the Earth Orbiting System Synthetic Aperture Radar (EOS SAR) program is to help develop the modeling and observational capabilities to predict and monitor terrestrial and oceanic processes that are either causing global change or resulting from global change. Specifically, the EOS SAR will provide important geophysical products to the EOS data set to improve our understanding of the state and functioning of the Earth system. The strategy for the EOS SAR program is to define the instrument requirements based on required input to geophysical algorithms, provide the processing capability and algorithms to generate such products on the required spatial (global) and temporal (3-5 days) scales, and to provide the spaceborne instrumentation with international partnerships. Initially this partnership has been with Germany; currently we are exploring broader international partnerships. A MultiSAR approach to the EOS SAR which includes a number of SARs provided by Japan, ESA, Germany, Canada, and the US in synergistic orbits could be used to attain a truly global monitoring capability using multifrequency polarimetric signatures. These concepts and several options for mission scenarios will be presented.

  11. ISRO's dual frequency airborne SAR pre-cursor to NISAR

    NASA Astrophysics Data System (ADS)

    Ramanujam, V. Manavala; Suneela, T. J. V. D.; Bhan, Rakesh

    2016-05-01

    The Indian Space Research Organisation (ISRO) and the National Aeronautics and Space Administration (NASA) have jointly embarked on NASA-ISRO Synthetic Aperture Radar (NISAR) operating in L-band and S-band, which will map Earth's surface every 12 days. As a pre-cursor to the NISAR mission, ISRO is planning an airborne SAR (L&S band) which will deliver NISAR analogue data products to the science community. ISRO will develop all the hardware with the aim of adhering to system design aspects of NISAR to the maximum extent possible. It is a fully polarimetric stripmap SAR and can be operated in single, dual, compact, quasi-quad and full polarimetry modes. It has wide incidence angle coverage from 24°-77° with swath coverage from 5.5km to 15 km. Apart from simultaneous imaging operations, this system can also operate in standalone L/S SAR modes. This system is planned to operate from an aircraft platform with nominal altitude of 8000meters. Antenna for this SAR will be rigidly mounted to the aircraft, whereas, motion compensation will be implemented in the software processor to generate data products. Data products for this airborne SAR will be generated in slant & ground range azimuth dimension and geocoded in HDF5/Geotiff formats. This airborne SAR will help to prepare the Indian scientific community for optimum utilization of NISAR data. In-order to collect useful science data, airborne campaigns are planned from end of 2016 onwards.

  12. Rapid Urban Mapping Using SAR/Optical Imagery Synergy

    PubMed Central

    Corbane, Christina; Faure, Jean-François; Baghdadi, Nicolas; Villeneuve, Nicolas; Petit, Michel

    2008-01-01

    This paper highlights the potential of combining Synthetic Aperture Radar (SAR) and optical data for operational rapid urban mapping. An algorithm consisting of a completely unsupervised procedure for processing pairs of co-registered SAR/optical images is proposed. In a first stage, a texture analysis is conducted independently on the two images using eight different chain-based Gaussian models. In a second stage, the resulting texture images are partitioned by an unsupervised fuzzy K-means approach. Finally, a fuzzy decision rule is used to aggregate the results provided by the classification of texture images obtained from the pair of SAR and optical images. The method was tested and validated on images of Bucharest (Romania) and Cayenne (French Guiana). These two study areas are of different terrain relief, urban settlement structure and land cover complexity. The data set included Radarsat-1/ENVISAT and SPOT-4/5 images. The developed SAR/optical information fusion scheme improved the capabilities of urban areas extraction when compared with the separate use of SAR and optical sensors. It also proved to be suitable for monitoring urbanization development. The encouraging results thus confirm the potential of combining information from SAR and optical sensors for timely urban area analysis, as required in cases of disaster management and planning in urban sprawl areas.

  13. From Maxwell's Equations to Polarimetric SAR Images: A Simulation Approach

    PubMed Central

    Sant'Anna, Sidnei J. S.; da S. Lacava, J. C.; Fernandes, David

    2008-01-01

    A new electromagnetic approach for the simulation of polarimetric SAR images is proposed. It starts from Maxwell's equations, employs the spectral domain full-wave technique, the moment method, and the stationary phase method to compute the far electromagnetic fields scattered by multilayer structures. A multilayer structure is located at each selected position of a regular rectangular grid of coordinates, which defines the scene area under imaging. The grid is determined taking into account the elementary scatter size and SAR operational parameters, such as spatial resolution, pixel spacing, look angle and platform altitude. A two-dimensional separable “sinc” function to represent the SAR spread point function is also considered. Multifrequency sets of single-look polarimetric SAR images are generated, in L-, C- and X-bands and the images are evaluated using several measurements commonly employed in SAR data analysis. The evaluation shows that the proposed simulation process is working properly, since the obtained results are in accordance with those presented in the literature. Therefore, this new approach becomes suitable for carrying out theoretical and practical studies using polarimetric SAR images.

  14. TEC retrieval from spaceborne SAR data and its applications

    NASA Astrophysics Data System (ADS)

    Wang, Cheng; Zhang, Min; Xu, Zheng-Wen; Zhao, Hai-Sheng

    2014-10-01

    It is well known that the spaceborne synthetic aperture radar (SAR) at VHF-UHF band can be seriously affected by the ionosphere. Thus, the geophysical information of the ionosphere will be embedded in the low-frequency SAR echoes after they transverse the ionosphere. Correspondingly, the total electron content (TEC), a typical ionospheric information parameter, can be retrieved from the spaceborne SAR data. However, the existing dual-band techniques for TEC retrieval usually do not include consideration of multiple scattering effects caused by turbulent ionosphere, which plays an important role in the total path delay of signal under the strong fluctuation regimes. The result of TEC retrieval is therefore inaccurate and not applicable. Aiming at this issue, first, this paper analyzes the effects of regular background and the irregularity of electron density on SAR at L-band, and the theoretical formulation is given. Then, a triband path delay technique of TEC retrieval based on the SAR data is proposed. By using three path delays corresponding to three specific frequencies within the signal bandwidth, this technique can remove the errors of multiple scattering due to the irregularity, and a high accuracy resolution of TEC value therefore can be obtained. Meanwhile, the sensitivity of this technique is analyzed. Finally, compared with traditional dual-band technique, the numerical simulations show that the correction of SAR imaging based on triband technique is improved significantly. In addition, the resolution of reconstruction imaging using computerized ionospheric tomography performs significantly better based on the triband technique.

  15. SAR-based vibrometry using the fractional Fourier transform

    NASA Astrophysics Data System (ADS)

    Campbell, Justin B.; Wang, Qi; Ade-Bello, Jelili; Caudana, Humberto; Trujillo, Nicole B.; Bhatta, Ishwor; Dunkel, Ralf; Atwood, Thomas; Doerry, Armin; Gerstle, Walter H.; Santhanam, Balu; Hayat, Majeed M.

    2015-05-01

    A fundamental assumption when applying Synthetic Aperture Radar (SAR) to a ground scene is that all targets are motionless. If a target is not stationary, but instead vibrating in the scene, it will introduce a non-stationary phase modulation, termed the micro-Doppler effect, into the returned SAR signals. Previously, the authors proposed a pseudosubspace method, a modification to the Discrete Fractional Fourier Transform (DFRFT), which demonstrated success for estimating the instantaneous accelerations of vibrating objects. However, this method may not yield reliable results when clutter in the SAR image is strong. Simulations and experimental results have shown that the DFRFT method can yield reliable results when the signal-to-clutter ratio (SCR) > 8 dB. Here, we provide the capability to determine a target's frequency and amplitude in a low SCR environment by presenting two methods that can perform vibration estimations when SCR < 3 dB. The first method is a variation and continuation of the subspace approach proposed previously in conjunction with the DFRFT. In the second method, we employ the dual-beam SAR collection architecture combined with the extended Kalman filter (EKF) to extract information from the returned SAR signals about the vibrating target. We also show the potential for extending this SAR-based capability to remotely detect and classify objects housed inside buildings or other cover based on knowing the location of vibrations as well as the vibration histories of the vibrating structures that house the vibrating objects.

  16. Surface displacement studies using differential SAR interferometry: an overview

    NASA Astrophysics Data System (ADS)

    Gupta, Sonal; Sajith V., K.; Arora, Manoj K.; Sharma, Mukut L.

    2006-12-01

    The differential SAR interferometry (DInSAR) has been increasing used to monitor ground surface displacements, which may be caused by various natural disasters such as earthquakes, landslides, mining activities, avalanches etc. Conventionally, these displacements were being estimated through field measurements, which are time consuming, hazardous and with data collected over few point locations. Since all the development and rehabilitation works after a natural disaster strikes is carried out on regional basis, any information at spatial level is advantageous in planning, management and monitoring activities. In recent years, the application of Differential SAR interferometry is gaining momentum to estimate the surface displacements at millimeter level accuracy. The displacement maps produced via this technique provide information at spatial level in the region thereby assisting in judicious developmental and planning works in an efficient and cost-effective manner. The aim of this paper is provide an overview of the use of Differential SAR Interferometry (DinSAR) technology for the study of surface displacements. As a case study, land subsidence occurred due to coal mining in Jharia coal fields, Jharkhand, have been estimated through this technique. All the procedural steps in implementing the approach based on DinSAR have been explained in a simplified manner.

  17. SAR backscatter from coniferous forest gaps

    NASA Technical Reports Server (NTRS)

    Day, John L.; Davis, Frank W.

    1992-01-01

    A study is in progress comparing Airborne Synthetic Aperture Radar (AIRSAR) backscatter from coniferous forest plots containing gaps to backscatter from adjacent gap-free plots. Issues discussed are how do gaps in the range of 400 to 1600 sq m (approximately 4-14 pixels at intermediate incidence angles) affect forest backscatter statistics and what incidence angles, wavelengths, and polarizations are most sensitive to forest gaps. In order to visualize the slant-range imaging of forest and gaps, a simple conceptual model is used. This strictly qualitative model has led us to hypothesize that forest radar returns at short wavelengths (eg., C-band) and large incidence angles (e.g., 50 deg) should be most affected by the presence of gaps, whereas returns at long wavelengths and small angles should be least affected. Preliminary analysis of 1989 AIRSAR data from forest near Mt. Shasta supports the hypothesis. Current forest backscatter models such as MIMICS and Santa Barbara Discontinuous Canopy Backscatter Model have in several cases correctly predicted backscatter from forest stands based on inputs of measured or estimated forest parameters. These models do not, however, predict within-stand SAR scene texture, or 'intrinsic scene variability' as Ulaby et al. has referred to it. For instance, the Santa Barbara model, which may be the most spatially coupled of the existing models, is not truly spatial. Tree locations within a simulated pixel are distributed according to a Poisson process, as they are in many natural forests, but tree size is unrelated to location, which is not the case in nature. Furthermore, since pixels of a simulated stand are generated independently in the Santa Barbara model, spatial processes larger than one pixel are not modeled. Using a different approach, Oliver modeled scene texture based on an hypothetical forest geometry. His simulated scenes do not agree well with SAR data, perhaps due to the simple geometric model used. Insofar as texture

  18. InSAR Scientific Computing Environment

    NASA Technical Reports Server (NTRS)

    Rosen, Paul A.; Sacco, Gian Franco; Gurrola, Eric M.; Zabker, Howard A.

    2011-01-01

    This computing environment is the next generation of geodetic image processing technology for repeat-pass Interferometric Synthetic Aperture (InSAR) sensors, identified by the community as a needed capability to provide flexibility and extensibility in reducing measurements from radar satellites and aircraft to new geophysical products. This software allows users of interferometric radar data the flexibility to process from Level 0 to Level 4 products using a variety of algorithms and for a range of available sensors. There are many radar satellites in orbit today delivering to the science community data of unprecedented quantity and quality, making possible large-scale studies in climate research, natural hazards, and the Earth's ecosystem. The proposed DESDynI mission, now under consideration by NASA for launch later in this decade, would provide time series and multiimage measurements that permit 4D models of Earth surface processes so that, for example, climate-induced changes over time would become apparent and quantifiable. This advanced data processing technology, applied to a global data set such as from the proposed DESDynI mission, enables a new class of analyses at time and spatial scales unavailable using current approaches. This software implements an accurate, extensible, and modular processing system designed to realize the full potential of InSAR data from future missions such as the proposed DESDynI, existing radar satellite data, as well as data from the NASA UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar), and other airborne platforms. The processing approach has been re-thought in order to enable multi-scene analysis by adding new algorithms and data interfaces, to permit user-reconfigurable operation and extensibility, and to capitalize on codes already developed by NASA and the science community. The framework incorporates modern programming methods based on recent research, including object-oriented scripts controlling legacy and

  19. VOLInSAR-PF, the InSAR Volcano Observatory Service at Piton de la Fournaise Volcano (La Reunion Island).

    NASA Astrophysics Data System (ADS)

    Froger, Jean-Luc; Cayol, Valérie; Augier, Aurélien; Souriot, Thierry

    2010-05-01

    Since 2003, we carry out a systematic InSAR survey of the Piton de la Fournaise volcano, Reunion Island, in the framework of an AO-ENVISAT project. Since 2005 this activity gets the status of Observatory Service of the Observatoire de Physique du Globe de Clermont-Ferrand (OPGC). From 375 ASAR images acquired between 2003 and 2010, we have produced more than 2100 interferograms that allowed us to map the deformations related to 21 eruptions and thus to better understand the internal processes acting during each eruption. In the same time, we have developed an automatic procedure to provide full resolution interferograms, trough a dedicated WEB site, to the Volcano Observatory of Piton de la Fournaise (OVPF), and our other partners, within a few hours after receiving the ASAR images. In this way, our work is a first step toward an operational system of InSAR monitoring of volcanic activity. Since the beginning of 2010, the VOLInSAR-PF database is also open to the entire community, trough an anonymous login that gives access to slightly reduced resolution interferograms. We will present the VOLInSAR-PF database, the main results it provides concerning the way Piton de la Fournaise is deforming, and the main perspectives for monitoring provided by the new InSAR data (PALSAR-ALOS, TerraSAR-X, RADARSAT-2, COSMO-Skymed) we are beginning to integrate in the database.

  20. Generalized energy-aperture product limit for multi-beam and spotlight SARs

    SciTech Connect

    Karr, T.J.

    1995-12-21

    The SAR energy-aperture product limit is extended to multi-beam SARS, Spotlight and moving spotlight SARS. This fundamental limit bounds the tradeoff between energy and antenna size. The kinematic relations between design variables such as platform speed, pulse repetition frequency, beam width and area rate are analyzed in a unified framework applicable to a wide variety of SARs including strip maps, spotlights, vermer arrays and multi-beam SARS, both scanning and swept-beam. Then the energy-aperture product limit is derived from the signal-to noise requirement and the kinematic constraints. The derivation clarifies impact of multiple beams and spotlighting on SAR performance.

  1. Mitigating illumination gradients in a SAR image based on the image data and antenna beam pattern

    SciTech Connect

    Doerry, Armin W.

    2013-04-30

    Illumination gradients in a synthetic aperture radar (SAR) image of a target can be mitigated by determining a correction for pixel values associated with the SAR image. This correction is determined based on information indicative of a beam pattern used by a SAR antenna apparatus to illuminate the target, and also based on the pixel values associated with the SAR image. The correction is applied to the pixel values associated with the SAR image to produce corrected pixel values that define a corrected SAR image.

  2. Geodetic imaging of tectonic deformation with InSAR

    NASA Astrophysics Data System (ADS)

    Fattahi, Heresh

    Precise measurements of ground deformation across the plate boundaries are crucial observations to evaluate the location of strain localization and to understand the pattern of strain accumulation at depth. Such information can be used to evaluate the possible location and magnitude of future earthquakes. Interferometric Synthetic Aperture Radar (InSAR) potentially can deliver small-scale (few mm/yr) ground displacement over long distances (hundreds of kilometers) across the plate boundaries and over continents. However, Given the ground displacement as our signal of interest, the InSAR observations of ground deformation are usually affected by several sources of systematic and random noises. In this dissertation I identify several sources of systematic and random noise, develop new methods to model and mitigate the systematic noise and to evaluate the uncertainty of the ground displacement measured with InSAR. I use the developed approach to characterize the tectonic deformation and evaluate the rate of strain accumulation along the Chaman fault system, the western boundary of the India with Eurasia tectonic plates. I evaluate the bias due to the topographic residuals in the InSAR range-change time-series and develope a new method to estimate the topographic residuals and mitigate the effect from the InSAR range-change time-series (Chapter 2). I develop a new method to evaluate the uncertainty of the InSAR velocity field due to the uncertainty of the satellite orbits (Chapter 3) and a new algorithm to automatically detect and correct the phase unwrapping errors in a dense network of interferograms (Chapter 4). I develop a new approach to evaluate the impact of systematic and stochastic components of the tropospheric delay on the InSAR displacement time-series and its uncertainty (Chapter 5). Using the new InSAR time-series approach developed in the previous chapters, I study the tectonic deformation across the western boundary of the India plate with Eurasia and

  3. Applying target shadow models for SAR ATR

    NASA Astrophysics Data System (ADS)

    Papson, Scott; Narayanan, Ram M.

    2007-04-01

    Recent work has suggested that target shadows in synthetic aperture radar (SAR) images can be used effectively to aid in target classification. The method outlined in this paper has four steps - segmentation, representation, modeling, and selection. Segmentation is the process by which a smooth, background-free representation of the target's shadow is extracted from an image chip. A chain code technique is then used to represent the shadow boundary. Hidden Markov modeling is applied to sets of chain codes for multiple targets to create a suitable bank of target representations. Finally, an ensemble framework is proposed for classification. The proposed model selection process searches for an optimal ensemble of models based on various target model configurations. A five target subset of the MSTAR database is used for testing. Since the shadow is a back-projection of the target profile, some aspect angles will contain more discriminatory information then others. Therefore, performance is investigated as a function of aspect angle. Additionally, the case of multiple target looks is considered. The capability of the shadow-only classifier to enhance more traditional classification techniques is examined.

  4. Robust SAR ATR by hedging against uncertainty

    NASA Astrophysics Data System (ADS)

    Hoffman, John R.; Mahler, Ronald P. S.; Ravichandran, Ravi B.; Huff, Melvyn; Musick, Stanton

    2002-07-01

    For the past two years in this conference, we have described techniques for robust identification of motionless ground targets using single-frame Synthetic Aperture Radar (SAR) data. By robust identification, we mean the problem of determining target ID despite the existence of confounding statistically uncharacterizable signature variations. Such variations can be caused by effects such as mud, dents, attachment of nonstandard equipment, nonstandard attachment of standard equipment, turret articulations, etc. When faced with such variations, optimal approaches can often behave badly-e.g., by mis-identifying a target type with high confidence. A basic element of our approach has been to hedge against unknowable uncertainties in the sensor likelihood function by specifying a random error bar (random interval) for each value of the likelihood function corresponding to any given value of the input data. Int his paper, we will summarize our recent results. This will include a description of the fuzzy maximum a posteriori (MAP) estimator. The fuzzy MAP estiamte is essentially the set of conventional MAP estimates that are plausible, given the assumed uncertainty in the problem. Despite its name, the fuzzy MAP is derived rigorously from first probabilistic principles based on random interval theory.

  5. Bandwidth requirements for fine resolution squinted SAR

    SciTech Connect

    DOERRY,ARMIN W.

    2000-03-01

    The conventional rule-of-thumb for Synthetic Aperture Radar is that an RF bandwidth of c/(2{rho}{sub r}) is required to image a scene at the desired slant-range resolution {rho}{sub r}, and perhaps a little more to account for window functions and sidelobe control. This formulation is based on the notion that the total bandwidth required is the same bandwidth that is required for a single pulse. What is neglected is that efficient processing of an entire synthetic aperture of pulses will often require different frequency content for each of the different pulses that makeup a synthetic aperture. Consequently, the total RF bandwidth required of a Synthetic Aperture Radar may then be substantially wider than the bandwidth of any single pulse. The actual RF bandwidth required depends strongly on flight geometry, owing to the desire for a radar to maintain a constant projection of the Fourier space collection surface onto the {omega}{sub y} axis. Long apertures required for fine azimuth resolution, and severe squint angles with steep depression angles may require total RF bandwidths well beyond the minimum bandwidth required of any single transmitted pulse, perhaps even by a factor of two or more. Accounting for this is crucial to designing efficient versatile high-performance imaging radars. This paper addresses how a data set conducive to efficient processing might increase the total RF bandwidth, and presents examples of how a fixed RF bandwidth might then limit SAR geometries.

  6. [SARS, avian influenza, and human metapneumovirus infection].

    PubMed

    Casas, Inmaculada; Pozo, Francisco

    2005-01-01

    Beginning in the 1950s respiratory viruses have been gradually discovered by isolation in cell cultures The last were the coronaviruses in the 1960s. No new respiratory viruses were discovered until 2001 when human metapneumovirus was found in respiratory specimens from children with bronchiolitis. A year later, in November 2002, severe acute respiratory syndrome (SARS) suddenly appeared as atypical pneumonia. A novel virus belonging to the Coronaviridae family was found to be a cause of this infection. In 2004, a second coronavirus was discovered (CoV-NL63) and in 2005 a third new coronavirus was described (CoV-HKU1). In addition, several subtypes of the influenza A virus, previously known to infect only poultry and wild birds, were recently found to have been directly transmitted to humans. Respiratory infection has been a considerable problem for humans for centuries. Now, in the 21st century, with new associated viruses continuously emerging, it remains an important field for work. PMID:16159544

  7. Anisotropic model-based SAR processing

    NASA Astrophysics Data System (ADS)

    Knight, Chad; Gunther, Jake; Moon, Todd

    2013-05-01

    Synthetic aperture radar (SAR) collections that integrate over a wide range of aspect angles hold the potentional for improved resolution and fosters improved scene interpretability and target detection. However, in practice it is difficult to realize the potential due to the anisotropic scattering of objects in the scene. The radar cross section (RCS) of most objects changes as a function of aspect angle. The isotropic assumption is tacitly made for most common image formation algorithms (IFA). For wide aspect scenarios one way to account for anistropy would be to employ a piecewise linear model. This paper focuses on such a model but it incorporates aspect and spatial magnitude filters in the image formation process. This is advantageous when prior knowledge is available regarding the desired targets' RCS signature spatially and in aspect. The appropriate filters can be incorporated into the image formation processing so that specific targets are emphasized while other targets are suppressed. This is demonstrated on the Air Force Research Laboratory (AFRL) GOTCHA1 data set to demonstrate the utility of the proposed approach.

  8. Measuring Thermokarst Subsidence Using InSAR: Potential and Pitfalls

    NASA Astrophysics Data System (ADS)

    Liu, L.; Schaefer, K. M.; Chen, A. C.; Gusmeroli, A.; Zebker, H. A.; Zhang, T.

    2014-12-01

    Thawing of ice-rich permafrost results in irregular, depressed landforms known as thermokarst terrain. The significant subsidence leading to thermokarst features can expand lakes, drain lakes, accelerate thaw, disturb the soil column, and promote erosion. Consequently, it affects many permafrost-region processes including vegetation succession, hydrology, and carbon storage and cycling. Many remote sensing studies identify thermokarst landforms and catalog their ever-changing areas. Yet the intrinsic dynamic thermokarst process, namely surface subsidence, remains a challenge to map and is seldom examined using remote sensing methods. Interferometric Synthetic Aperture Radar (InSAR) is a remote sensing technique that uses a time-series of satellite SAR images to measure cm-level land surface deformation. We demonstrate the capabilities and limitations of space-borne InSAR data to map thermokarst subsidence at a site located near Prudhoe Bay, on the North Slope of Alaska. A pipeline access road was constructed at this site in the 1970s, and is likely to have triggered the thawing of the region's permafrost, causing subsequent expansion of thermokarst-landform terrain. Our InSAR analysis using ALOS PALSAR images reveals that the thermokarst landforms in this region have undergone up to 10 cm of surface subsidence each summer from 2007 to 2010. This pilot study demonstrates the application of InSAR to map localized mass movement in permafrost terrain. We also illustrate how the effectiveness and accuracy of InSAR measurements are limited by several factors such as loss of interferometric coherence due to fast changes of ground surface conditions, spatial and temporal resolutions of InSAR data, and difficulty separating long-term and seasonal deformation signals.

  9. SARS plague: duty of care or medical heroism?

    PubMed

    Tai, Dessmon Y H

    2006-05-01

    Severe acute respiratory syndrome (SARS) is a new infectious disease that emerged in mid- November 2002 in Guangdong, southern China. The global pandemic began in late February 2003 in Hong Kong. By the time SARS was declared contained on 5 July 2003 by the World Health Organization (WHO), it had afflicted 8096 patients in 29 countries. No other disease had had such a phenomenal impact on healthcare workers (HCWs), who formed about 21% of SARS patients. In Vietnam, Canada and Singapore, HCWs accounted for 57%, 43% and 41% of SAR patients, respectively. At the beginning of the outbreak, there was practically no information on this disease, which did not even have a name until 16 March 2003, except that it was infectious and could result in potentially fatal respiratory failure. Indeed, HCWs had lost their lives to SARS. Understandably, some HCWs refused to look after SARS patients or even resigned. Initially, much negative publicity was given to such HCWs. It was a very trying time for HCWs as many were also ostracised by the society which they served. They were perceived to be a potential source of infection in the community because of their contact with SARS patients, whom they risked their lives looking after. Subsequently, as we learnt more about the disease and educated the public about the plight of the frontline HCWs, the public gave the frontline HCWs tremendous support and even honoured them as heroes. Being in the medical profession, caring for patients is one of our expected responsibilities. On the other hand, as public citizens, HCWs have the right to resign when they feel that their responsibility to their families should take priority over that to their patients. As a result of this scourge, each HCW learnt to decide if caring for patients is their chosen profession and vocation. Many chose to live up the Hippocratic oath. PMID:16830007

  10. UAVSAR and TerraSAR-X Based InSAR Detection of Localized Subsidence in the New Orleans Area

    NASA Astrophysics Data System (ADS)

    Blom, R. G.; An, K.; Jones, C. E.; Latini, D.

    2014-12-01

    Vulnerability of the US Gulf coast to inundation has received increased attention since hurricanes Katrina and Rita. Compounding effects of sea level rise, wetland loss, and regional and local subsidence makes flood protection a difficult challenge, and particularly for the New Orleans area. Key to flood protection is precise knowledge of elevations and elevation changes. Analysis of historical and continuing geodetic measurements show surprising complexity, including locations subsiding more rapidly than considered during planning of hurricane protection and coastal restoration projects. Combining traditional, precise geodetic data with interferometric synthetic aperture radar (InSAR) observations can provide geographically dense constraints on surface deformation. The Gulf Coast environment is challenging for InSAR techniques, especially with systems not designed for interferometry. We use two InSAR capable systems, the L- band (24 cm wavelength) airborne JPL/NASA UAVSAR, and the DLR/EADS Astrium spaceborne TerraSAR X-band (3 cm wavelength), and compare results. First, we are applying pair-wise InSAR to the longer wavelength UAVSAR data to detect localized elevation changes potentially impacting flood protection infrastructure from 2009 - 2014. We focus on areas on and near flood protection infrastructure to identify changes indicative of subsidence, structural deformation, and/or seepage. The Spaceborne TerraSAR X-band SAR system has relatively frequent observations, and dense persistent scatterers in urban areas, enabling measurement of very small displacements. We compare L-band UAVSAR results with permanent scatterer (PS-InSAR) and Short Baseline Subsets (SBAS) interferometric analyses of a stack composed by 28 TerraSAR X-band images acquired over the same period. Thus we can evaluate results from the different radar frequencies and analyses techniques. Preliminary results indicate subsidence features potentially of a variety of causes, including ground water

  11. Memory T cell responses targeting the SARS coronavirus persist up to 11 years post-infection.

    PubMed

    Ng, Oi-Wing; Chia, Adeline; Tan, Anthony T; Jadi, Ramesh S; Leong, Hoe Nam; Bertoletti, Antonio; Tan, Yee-Joo

    2016-04-12

    Severe acute respiratory syndrome (SARS) is a highly contagious infectious disease which first emerged in late 2002, caused by a then novel human coronavirus, SARS coronavirus (SARS-CoV). The virus is believed to have originated from bats and transmitted to human through intermediate animals such as civet cats. The re-emergence of SARS-CoV remains a valid concern due to the continual persistence of zoonotic SARS-CoVs and SARS-like CoVs (SL-CoVs) in bat reservoirs. In this study, the screening for the presence of SARS-specific T cells in a cohort of three SARS-recovered individuals at 9 and 11 years post-infection was carried out, and all memory T cell responses detected target the SARS-CoV structural proteins. Two CD8(+) T cell responses targeting the SARS-CoV membrane (M) and nucleocapsid (N) proteins were characterized by determining their HLA restriction and minimal T cell epitope regions. Furthermore, these responses were found to persist up to 11 years post-infection. An absence of cross-reactivity of these CD8(+) T cell responses against the newly-emerged Middle East respiratory syndrome coronavirus (MERS-CoV) was also demonstrated. The knowledge of the persistence of SARS-specific celullar immunity targeting the viral structural proteins in SARS-recovered individuals is important in the design and development of SARS vaccines, which are currently unavailable. PMID:26954467

  12. Multitemporal observations of sugarcane by TerraSAR-X images.

    PubMed

    Baghdadi, Nicolas; Cresson, Rémi; Todoroff, Pierre; Moinet, Soizic

    2010-01-01

    The objective of this study is to investigate the potential of TerraSAR-X (X-band) in monitoring sugarcane growth on Reunion Island (located in the Indian Ocean). Multi-temporal TerraSAR data acquired at various incidence angles (17°, 31°, 37°, 47°, 58°) and polarizations (HH, HV, VV) were analyzed in order to study the behaviour of SAR (synthetic aperture radar) signal as a function of sugarcane height and NDVI (Normalized Difference Vegetation Index). The potential of TerraSAR for mapping the sugarcane harvest was also studied. Radar signal increased quickly with crop height until a threshold height, which depended on polarization and incidence angle. Beyond this threshold, the signal increased only slightly, remained constant, or even decreased. The threshold height is slightly higher with cross polarization and higher incidence angles (47° in comparison with 17° and 31°). Results also showed that the co-polarizations channels (HH and VV) were well correlated. High correlation between SAR signal and NDVI calculated from SPOT-4/5 images was observed. TerraSAR data showed that after strong rains the soil contribution to the backscattering of sugarcane fields can be important for canes with heights of terminal visible dewlap (htvd) less than 50 cm (total cane heights around 155 cm). This increase in radar signal after strong rains could involve an ambiguity between young and mature canes. Indeed, the radar signal on TerraSAR images acquired in wet soil conditions could be of the same order for fields recently harvested and mature sugarcane fields, making difficult the detection of cuts. Finally, TerraSAR data at high spatial resolution were shown to be useful for monitoring sugarcane harvest when the fields are of small size or when the cut is spread out in time. The comparison between incidence angles of 17°, 37° and 58° shows that 37° is more suitable to monitor the sugarcane harvest. The cut is easily detectable on TerraSAR images for data acquired

  13. Multitemporal Observations of Sugarcane by TerraSAR-X Images

    PubMed Central

    Baghdadi, Nicolas; Cresson, Rémi; Todoroff, Pierre; Moinet, Soizic

    2010-01-01

    The objective of this study is to investigate the potential of TerraSAR-X (X-band) in monitoring sugarcane growth on Reunion Island (located in the Indian Ocean). Multi-temporal TerraSAR data acquired at various incidence angles (17°, 31°, 37°, 47°, 58°) and polarizations (HH, HV, VV) were analyzed in order to study the behaviour of SAR (synthetic aperture radar) signal as a function of sugarcane height and NDVI (Normalized Difference Vegetation Index). The potential of TerraSAR for mapping the sugarcane harvest was also studied. Radar signal increased quickly with crop height until a threshold height, which depended on polarization and incidence angle. Beyond this threshold, the signal increased only slightly, remained constant, or even decreased. The threshold height is slightly higher with cross polarization and higher incidence angles (47° in comparison with 17° and 31°). Results also showed that the co-polarizations channels (HH and VV) were well correlated. High correlation between SAR signal and NDVI calculated from SPOT-4/5 images was observed. TerraSAR data showed that after strong rains the soil contribution to the backscattering of sugarcane fields can be important for canes with heights of terminal visible dewlap (htvd) less than 50 cm (total cane heights around 155 cm). This increase in radar signal after strong rains could involve an ambiguity between young and mature canes. Indeed, the radar signal on TerraSAR images acquired in wet soil conditions could be of the same order for fields recently harvested and mature sugarcane fields, making difficult the detection of cuts. Finally, TerraSAR data at high spatial resolution were shown to be useful for monitoring sugarcane harvest when the fields are of small size or when the cut is spread out in time. The comparison between incidence angles of 17°, 37° and 58° shows that 37° is more suitable to monitor the sugarcane harvest. The cut is easily detectable on TerraSAR images for data acquired

  14. High-Level Performance Modeling of SAR Systems

    NASA Technical Reports Server (NTRS)

    Chen, Curtis

    2006-01-01

    SAUSAGE (Still Another Utility for SAR Analysis that s General and Extensible) is a computer program for modeling (see figure) the performance of synthetic- aperture radar (SAR) or interferometric synthetic-aperture radar (InSAR or IFSAR) systems. The user is assumed to be familiar with the basic principles of SAR imaging and interferometry. Given design parameters (e.g., altitude, power, and bandwidth) that characterize a radar system, the software predicts various performance metrics (e.g., signal-to-noise ratio and resolution). SAUSAGE is intended to be a general software tool for quick, high-level evaluation of radar designs; it is not meant to capture all the subtleties, nuances, and particulars of specific systems. SAUSAGE was written to facilitate the exploration of engineering tradeoffs within the multidimensional space of design parameters. Typically, this space is examined through an iterative process of adjusting the values of the design parameters and examining the effects of the adjustments on the overall performance of the system at each iteration. The software is designed to be modular and extensible to enable consideration of a variety of operating modes and antenna beam patterns, including, for example, strip-map and spotlight SAR acquisitions, polarimetry, burst modes, and squinted geometries.

  15. Detecting and monitoring UCG subsidence with InSAR

    SciTech Connect

    Mellors, R J; Foxall, W; Yang, X

    2012-03-23

    The use of interferometric synthetic aperture radar (InSAR) to measure surface subsidence caused by Underground Coal Gasification (UCG) is tested. InSAR is a remote sensing technique that uses Synthetic Aperture Radar images to make spatial images of surface deformation and may be deployed from satellite or an airplane. With current commercial satellite data, the technique works best in areas with little vegetation or farming activity. UCG subsidence is generally caused by roof collapse, which adversely affects UCG operations due to gas loss and is therefore important to monitor. Previous studies have demonstrated the usefulness of InSAR in measuring surface subsidence related to coal mining and surface deformation caused by a coal mining roof collapse in Crandall Canyon, Utah is imaged as a proof-of-concept. InSAR data is collected and processed over three known UCG operations including two pilot plants (Majuba, South Africa and Wulanchabu, China) and an operational plant (Angren, Uzbekistan). A clear f eature showing approximately 7 cm of subsidence is observed in the UCG field in Angren. Subsidence is not observed in the other two areas, which produce from deeper coal seams and processed a smaller volume. The results show that in some cases, InSAR is a useful tool to image UCG related subsidence. Data from newer satellites and improved algorithms will improve effectiveness.

  16. A new method for SAR measurement in MRI

    NASA Astrophysics Data System (ADS)

    Romano, Rocco; Acernese, Fausto; Indovina, Pietro Luigi; Barone, Fabrizio

    2008-03-01

    During an MR procedure, the patient absorbs a portion of the transmitted RF energy, which may result in tissue heating and other adverse effects, such as alterations in visual, auditory and neural functions. The Specific Absorption Rate (SAR), in W/kg, is the RF power absorbed per unit mass of tissue and is one of the most important parameters related with thermal effects and acts as a guideline for MRI safety. Strict limits to the SAR levels are imposed by patient safety international regulations (CEI - EN 60601 - 2 - 33) and SAR measurements are required in order to verify its respect. The recommended methods for mean SAR measurement are quite problematic and often require a maintenance man intervention and long stop machine. For example, in the CEI recommended pulse energy method, the presence of a maintenance man is required in order to correctly connect the required instrumentation; furthermore, the procedure is complex and requires remarkable processing and calculus. Simpler are the calorimetric methods, also if in this case long acquisition times are required in order to have significant temperature variations and accurate heat capacity knowledge (CEI - EN 60601 - 2 - 33). The phase transition method is a new method to measure SAR in MRI which has the advantages to be very simple and to overcome all the typical calorimetric method problems. It does not require in gantry temperature measurements, any specific heat or heat capacity knowledge, but only mass and time measurement.

  17. Modified Polar-Format Software for Processing SAR Data

    NASA Technical Reports Server (NTRS)

    Chen, Curtis

    2003-01-01

    HMPF is a computer program that implements a modified polar-format algorithm for processing data from spaceborne synthetic-aperture radar (SAR) systems. Unlike prior polar-format processing algorithms, this algorithm is based on the assumption that the radar signal wavefronts are spherical rather than planar. The algorithm provides for resampling of SAR pulse data from slant range to radial distance from the center of a reference sphere that is nominally the local Earth surface. Then, invoking the projection-slice theorem, the resampled pulse data are Fourier-transformed over radial distance, arranged in the wavenumber domain according to the acquisition geometry, resampled to a Cartesian grid, and inverse-Fourier-transformed. The result of this process is the focused SAR image. HMPF, and perhaps other programs that implement variants of the algorithm, may give better accuracy than do prior algorithms for processing strip-map SAR data from high altitudes and may give better phase preservation relative to prior polar-format algorithms for processing spotlight-mode SAR data.

  18. Advanced fractal approach for unsupervised classification of SAR images

    NASA Astrophysics Data System (ADS)

    Pant, Triloki; Singh, Dharmendra; Srivastava, Tanuja

    2010-06-01

    Unsupervised classification of Synthetic Aperture Radar (SAR) images is the alternative approach when no or minimum apriori information about the image is available. Therefore, an attempt has been made to develop an unsupervised classification scheme for SAR images based on textural information in present paper. For extraction of textural features two properties are used viz. fractal dimension D and Moran's I. Using these indices an algorithm is proposed for contextual classification of SAR images. The novelty of the algorithm is that it implements the textural information available in SAR image with the help of two texture measures viz. D and I. For estimation of D, the Two Dimensional Variation Method (2DVM) has been revised and implemented whose performance is compared with another method, i.e., Triangular Prism Surface Area Method (TPSAM). It is also necessary to check the classification accuracy for various window sizes and optimize the window size for best classification. This exercise has been carried out to know the effect of window size on classification accuracy. The algorithm is applied on four SAR images of Hardwar region, India and classification accuracy has been computed. A comparison of the proposed algorithm using both fractal dimension estimation methods with the K-Means algorithm is discussed. The maximum overall classification accuracy with K-Means comes to be 53.26% whereas overall classification accuracy with proposed algorithm is 66.16% for TPSAM and 61.26% for 2DVM.

  19. Developing an interactive teleradiology system for SARS diagnosis

    NASA Astrophysics Data System (ADS)

    Sun, Jianyong; Zhang, Jianguo; Zhuang, Jun; Chen, Xiaomeng; Yong, Yuanyuan; Tan, Yongqiang; Chen, Liu; Lian, Ping; Meng, Lili; Huang, H. K.

    2004-04-01

    Severe acute respiratory syndrome (SARS) is a respiratory illness that had been reported in Asia, North America, and Europe in last spring. Most of the China cases of SARS have occurred by infection in hospitals or among travelers. To protect the physicians, experts and nurses from the SARS during the diagnosis and treatment procedures, the infection control mechanisms were built in SARS hospitals. We built a Web-based interactive teleradiology system to assist the radiologists and physicians both in side and out side control area to make image diagnosis. The system consists of three major components: DICOM gateway (GW), Web-based image repository server (Server), and Web-based DICOM viewer (Viewer). This system was installed and integrated with CR, CT and the hospital information system (HIS) in Shanghai Xinhua hospital to provide image-based ePR functions for SARS consultation between the radiologists, physicians and experts inside and out side control area. The both users inside and out side the control area can use the system to process and manipulate the DICOM images interactively, and the system provide the remote control mechanism to synchronize their operations on images and display.

  20. A Localization Method for Multistatic SAR Based on Convex Optimization

    PubMed Central

    2015-01-01

    In traditional localization methods for Synthetic Aperture Radar (SAR), the bistatic range sum (BRS) estimation and Doppler centroid estimation (DCE) are needed for the calculation of target localization. However, the DCE error greatly influences the localization accuracy. In this paper, a localization method for multistatic SAR based on convex optimization without DCE is investigated and the influence of BRS estimation error on localization accuracy is analysed. Firstly, by using the information of each transmitter and receiver (T/R) pair and the target in SAR image, the model functions of T/R pairs are constructed. Each model function’s maximum is on the circumference of the ellipse which is the iso-range for its model function’s T/R pair. Secondly, the target function whose maximum is located at the position of the target is obtained by adding all model functions. Thirdly, the target function is optimized based on gradient descent method to obtain the position of the target. During the iteration process, principal component analysis is implemented to guarantee the accuracy of the method and improve the computational efficiency. The proposed method only utilizes BRSs of a target in several focused images from multistatic SAR. Therefore, compared with traditional localization methods for SAR, the proposed method greatly improves the localization accuracy. The effectivity of the localization approach is validated by simulation experiment. PMID:26566031

  1. Gb-Sar Interferometry for Structure Monitoring during Infrastructure Projects

    NASA Astrophysics Data System (ADS)

    Serrano Juan, A.; Vázquez-Suñé, E.; Monserrat, O.; Crosetto, M.; Hoffman, C.; Ledesma, A.; Criollo, R.; Pujades, E.; Velasco, V.; García, A.

    2015-12-01

    Monitoring is a necessary task for infrastructure projects. Ground-based synthetic aperture radar (GB-SAR) has been used in a large variety of displacement measurements. However, it has not yet been applied as a monitoring tool during construction projects. This paper aims to demonstrate that GB-SAR can be very helpful for understanding the mechanisms that control structure deformations and for identifying unexpected events and sensitive areas during construction projects. This could be done in a cost-effective way, which complements the traditional displacement measurements. An experiment was performed in the future railway station of La Sagrera, Barcelona (Spain) to demonstrate the utility of GB-SAR on structure monitoring during construction projects. In this experiment, GB-SAR precisely quantified wall displacements induced by dewatering. Manual data and numerical models have been used to confirm the measurements with a correlation analysis and by comparing measurements and deformation patterns, which have produced similar results. These results validate the use of the GB-SAR technique as a monitoring tool during construction projects.

  2. MAX-91: Polarimetric SAR results on Montespertoli site

    NASA Technical Reports Server (NTRS)

    Baronti, S.; Luciani, S.; Moretti, S.; Paloscia, S.; Schiavon, G.; Sigismondi, S.

    1993-01-01

    The polarimetric Synthetic Aperture Radar (SAR) is a powerful sensor for high resolution ocean and land mapping and particularly for monitoring hydrological parameters in large watersheds. There is currently much research in progress to assess the SAR operational capability as well as to estimate the accuracy achievable in the measurements of geophysical parameters with the presently available airborne and spaceborne sensors. An important goal of this research is to improve our understanding of the basic mechanisms that control the interaction of electro-magnetic waves with soil and vegetation. This can be done both by developing electromagnetic models and by analyzing statistical relations between backscattering and ground truth data. A systematic investigation, which aims at a better understanding of the information obtainable from the multi-frequency polarimetric SAR to be used in agro-hydrology, is in progress by our groups within the framework of SIR-C/X-SAR Project and has achieved a most significant milestone with the NASA/JPL Aircraft Campaign named MAC-91. Indeed this experiment allowed us to collect a large and meaningful data set including multi-temporal multi-frequency polarimetric SAR measurements and ground truth. This paper presents some significant results obtained over an agricultural flat area within the Montespertoli site, where intensive ground measurements were carried out. The results are critically discussed with special regard to the information associated with polarimetric data.

  3. A Localization Method for Multistatic SAR Based on Convex Optimization.

    PubMed

    Zhong, Xuqi; Wu, Junjie; Yang, Jianyu; Sun, Zhichao; Huang, Yuling; Li, Zhongyu

    2015-01-01

    In traditional localization methods for Synthetic Aperture Radar (SAR), the bistatic range sum (BRS) estimation and Doppler centroid estimation (DCE) are needed for the calculation of target localization. However, the DCE error greatly influences the localization accuracy. In this paper, a localization method for multistatic SAR based on convex optimization without DCE is investigated and the influence of BRS estimation error on localization accuracy is analysed. Firstly, by using the information of each transmitter and receiver (T/R) pair and the target in SAR image, the model functions of T/R pairs are constructed. Each model function's maximum is on the circumference of the ellipse which is the iso-range for its model function's T/R pair. Secondly, the target function whose maximum is located at the position of the target is obtained by adding all model functions. Thirdly, the target function is optimized based on gradient descent method to obtain the position of the target. During the iteration process, principal component analysis is implemented to guarantee the accuracy of the method and improve the computational efficiency. The proposed method only utilizes BRSs of a target in several focused images from multistatic SAR. Therefore, compared with traditional localization methods for SAR, the proposed method greatly improves the localization accuracy. The effectivity of the localization approach is validated by simulation experiment. PMID:26566031

  4. An automatic coastline detector for use with SAR images

    SciTech Connect

    Erteza, Ireena A.

    1998-09-01

    SAR imagery for coastline detection has many potential advantages over conventional optical stereoscopic techniques. For example, SAR does not have restrictions on being collected during daylight or when there is no cloud cover. In addition, the techniques for coastline detection witth SAR images can be automated. In this paper, we present the algorithmic development of an automatic coastline detector for use with SAR imagery. Three main algorithms comprise the automatic coastline detection algorithm, The first algorithm considers the image pre-processing steps that must occur on the original image in order to accentuate the land/water boundary. The second algorithm automatically follows along the accentuated land/water boundary and produces a single-pixel-wide coastline. The third algorithm identifies islands and marks them. This report describes in detail the development of these three algorithms. Examples of imagery are used throughout the paper to illustrate the various steps in algorithms. Actual code is included in appendices. The algorithms presented are preliminary versions that can be applied to automatic coastline detection in SAR imagery. There are many variations and additions to the algorithms that can be made to improve robustness and automation, as required by a particular application.

  5. Integration of SAR and DEM data: Geometrical considerations

    NASA Technical Reports Server (NTRS)

    Kropatsch, Walter G.

    1991-01-01

    General principles for integrating data from different sources are derived from the experience of registration of SAR images with digital elevation models (DEM) data. The integration consists of establishing geometrical relations between the data sets that allow us to accumulate information from both data sets for any given object point (e.g., elevation, slope, backscatter of ground cover, etc.). Since the geometries of the two data are completely different they cannot be compared on a pixel by pixel basis. The presented approach detects instances of higher level features in both data sets independently and performs the matching at the high level. Besides the efficiency of this general strategy it further allows the integration of additional knowledge sources: world knowledge and sensor characteristics are also useful sources of information. The SAR features layover and shadow can be detected easily in SAR images. An analytical method to find such regions also in a DEM needs in addition the parameters of the flight path of the SAR sensor and the range projection model. The generation of the SAR layover and shadow maps is summarized and new extensions to this method are proposed.

  6. Atmospheric Effects on InSAR Measurements and Their Mitigation

    PubMed Central

    Ding, Xiao-li; Li, Zhi-wei; Zhu, Jian-jun; Feng, Guang-cai; Long, Jiang-ping

    2008-01-01

    Interferometric Synthetic Aperture Radar (InSAR) is a powerful technology for observing the Earth surface, especially for mapping the Earth's topography and deformations. InSAR measurements are however often significantly affected by the atmosphere as the radar signals propagate through the atmosphere whose state varies both in space and in time. Great efforts have been made in recent years to better understand the properties of the atmospheric effects and to develop methods for mitigating the effects. This paper provides a systematic review of the work carried out in this area. The basic principles of atmospheric effects on repeat-pass InSAR are first introduced. The studies on the properties of the atmospheric effects, including the magnitudes of the effects determined in the various parts of the world, the spectra of the atmospheric effects, the isotropic properties and the statistical distributions of the effects, are then discussed. The various methods developed for mitigating the atmospheric effects are then reviewed, including the methods that are based on PSInSAR processing, the methods that are based on interferogram modeling, and those that are based on external data such as GPS observations, ground meteorological data, and satellite data including those from the MODIS and MERIS. Two examples that use MODIS and MERIS data respectively to calibrate atmospheric effects on InSAR are also given.

  7. Determining Titan surface topography from Cassini SAR data

    USGS Publications Warehouse

    Stiles, Bryan W.; Hensley, Scott; Gim, Yonggyu; Bates, David M.; Kirk, Randolph L.; Hayes, Alex; Radebaugh, Jani; Lorenz, Ralph D.; Mitchell, Karl L.; Callahan, Philip S.; Zebker, Howard; Johnson, William T.K.; Wall, Stephen D.; Lunine, Jonathan I.; Wood, Charles A.; Janssen, Michael; Pelletier, Frederic; West, Richard D.; Veeramacheneni, Chandini

    2009-01-01

    A technique, referred to as SARTopo, has been developed for obtaining surface height estimates with 10 km horizontal resolution and 75 m vertical resolution of the surface of Titan along each Cassini Synthetic Aperture Radar (SAR) swath. We describe the technique and present maps of the co-located data sets. A global map and regional maps of Xanadu and the northern hemisphere hydrocarbon lakes district are included in the results. A strength of the technique is that it provides topographic information co-located with SAR imagery. Having a topographic context vastly improves the interpretability of the SAR imagery and is essential for understanding Titan. SARTopo is capable of estimating surface heights for most of the SAR-imaged surface of Titan. Currently nearly 30% of the surface is within 100 km of a SARTopo height profile. Other competing techniques provide orders of magnitude less coverage. We validate the SARTopo technique through comparison with known geomorphological features such as mountain ranges and craters, and by comparison with co-located nadir altimetry, including a 3000 km strip that had been observed by SAR a month earlier. In this area, the SARTopo and nadir altimetry data sets are co-located tightly (within 5-10 km for one 500 km section), have similar resolution, and as expected agree closely in surface height. Furthermore the region contains prominent high spatial resolution topography, so it provides an excellent test of the resolution and precision of both techniques.

  8. Numerical Analysis of Orbital Perturbation Effects on Inclined Geosynchronous SAR.

    PubMed

    Dong, Xichao; Hu, Cheng; Long, Teng; Li, Yuanhao

    2016-01-01

    The geosynchronous synthetic aperture radar (GEO SAR) is susceptible to orbit perturbations, leading to orbit drifts and variations. The influences behave very differently from those in low Earth orbit (LEO) SAR. In this paper, the impacts of perturbations on GEO SAR orbital elements are modelled based on the perturbed dynamic equations, and then, the focusing is analyzed theoretically and numerically by using the Systems Tool Kit (STK) software. The accurate GEO SAR slant range histories can be calculated according to the perturbed orbit positions in STK. The perturbed slant range errors are mainly the first and second derivatives, leading to image drifts and defocusing. Simulations of the point target imaging are performed to validate the aforementioned analysis. In the GEO SAR with an inclination of 53° and an argument of perigee of 90°, the Doppler parameters and the integration time are different and dependent on the geometry configurations. Thus, the influences are varying at different orbit positions: at the equator, the first-order phase errors should be mainly considered; at the perigee and apogee, the second-order phase errors should be mainly considered; at other positions, first-order and second-order exist simultaneously. PMID:27598168

  9. Camouflage effectiveness of static nets in SAR images

    NASA Astrophysics Data System (ADS)

    Jersblad, Johan; Larsson, Christer

    2015-10-01

    We present a methodology to determine the camouflage effectiveness of static nets in a SAR image. There is currently no common recognized methodology within the signature management community in this research topic. One step towards establishing a common methodology is to use a standardized target to be camouflaged. We use the STANdard Decoy for CAmouflage Materials (STANDCAM) target developed by the German Army, WTD 52, Oberjettenberg. An ISAR measurement of the STANDCAM with a camouflage configuration is acquired as the first step of the method. The ISAR data is then blended with SAR data acquired in field trials. In the final SAR image a contrast metric between the target and background is extracted. The contrast measure is then the measure of the camouflage effectiveness. As an example of result we present ISAR measurements and determine the camouflage effectiveness in a SAR image using SAR blending for static nets with different electrical conductivity and design. This methodology presents a measure to determine the effectiveness of a static net on the STANDCAM target.

  10. Targeted Radiosensitization by the Chk1 Inhibitor SAR-020106

    SciTech Connect

    Borst, Gerben R.; McLaughlin, Martin; Kyula, Joan N.; Neijenhuis, Sari; Khan, Aadil; Good, James; Zaidi, Shane; Powell, Ned G.; Meier, Pascal; Collins, Ian; Garrett, Michelle D.; Verheij, Marcel; Harrington, Kevin J.

    2013-03-15

    Purpose: To explore the activity of a potent Chk1 inhibitor (SAR-020106) in combination with radiation. Methods and Materials: Colony and mechanistic in vitro assays and a xenograft in vivo model. Results: SAR-020106 suppressed-radiation-induced G{sub 2}/M arrest and reduced clonogenic survival only in p53-deficient tumor cells. SAR-020106 promoted mitotic entry following irradiation in all cell lines, but p53-deficient cells were likely to undergo apoptosis or become aneuploid, while p53 wild-type cells underwent a postmitotic G{sub 1} arrest followed by subsequent normal cell cycle re-entry. Following combined treatment with SAR-020106 and radiation, homologous-recombination-mediated DNA damage repair was inhibited in all cell lines. A significant increase in the number of pan-γH2AX-staining apoptotic cells was observed only in p53-deficient cell lines. Efficacy was confirmed in vivo in a clinically relevant human head-and-neck cell carcinoma xenograft model. Conclusion: The Chk1 inhibitor SAR-020106 is a potent radiosensitizer in tumor cell lines defective in p53 signaling.

  11. 1. RUINED PORTION OF SANTA ANA CANAL INTAKE ALONGSIDE SAR3 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. RUINED PORTION OF SANTA ANA CANAL INTAKE ALONGSIDE SAR-3 SYSTEM TUNNEL, JUST TO SOUTH OF SAR-2. VIEW TO SOUTHEAST. - Santa Ana River Hydroelectric System, Abandoned Tunnel, Redlands, San Bernardino County, CA

  12. 1. SAR1, SOUTHEAST AND SOUTHWEST ELEVATIONS, WITH SWITCH RACK AT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. SAR-1, SOUTHEAST AND SOUTHWEST ELEVATIONS, WITH SWITCH RACK AT LEFT, AND SANTA ANA WELL #1 AND STONE RETAINING WALLS AT RIGHT. VIEW TO NORTH. - Santa Ana River Hydroelectric System, SAR-1 Powerhouse, Redlands, San Bernardino County, CA

  13. SAR image registration in absolute coordinates using GPS carrier phase position and velocity information

    SciTech Connect

    Burgett, S.; Meindl, M.

    1994-09-01

    It is useful in a variety of military and commercial application to accurately register the position of synthetic aperture radar (SAR) imagery in absolute coordinates. The two basic SAR measurements, range and doppler, can be used to solve for the position of the SAR image. Imprecise knowledge of the SAR collection platform`s position and velocity vectors introduce errors in the range and doppler measurements and can cause the apparent location of the SAR image on the ground to be in error by tens of meters. Recent advances in carrier phase GPS techniques can provide an accurate description of the collection vehicle`s trajectory during the image formation process. In this paper, highly accurate carrier phase GPS trajectory information is used in conjunction with SAR imagery to demonstrate a technique for accurate registration of SAR images in WGS-84 coordinates. Flight test data will be presented that demonstrates SAR image registration errors of less than 4 meters.

  14. 12. OVERVIEW FROM FORMER RESIDENTIAL AREA NORTH OF SAR2, SHOWING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. OVERVIEW FROM FORMER RESIDENTIAL AREA NORTH OF SAR-2, SHOWING TRAIL UP TO FOREBAY, RETAINING WALL, PEPPER TREES, AND SAR-2 IN DISTANCE. VIEW TO SOUTH-SOUTHEAST. - Santa Ana River Hydroelectric System, Redlands, San Bernardino County, CA

  15. 29. SAR2, VIEW TO NORTH WITH EXCITERS AT LEFT. SCE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. SAR-2, VIEW TO NORTH WITH EXCITERS AT LEFT. SCE negative no. 1043, photographed June 6, 1912. Photograph by G. Haven Bishop. - Santa Ana River Hydroelectric System, SAR-2 Powerhouse, Redlands, San Bernardino County, CA

  16. 52. SAR1, OPERATOR WORKING GOVERNOR. EEC print no. GC0100390, no ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    52. SAR-1, OPERATOR WORKING GOVERNOR. EEC print no. G-C-01-00390, no date. Photograph by Benjamin F. Pearson. - Santa Ana River Hydroelectric System, SAR-1 Powerhouse, Redlands, San Bernardino County, CA

  17. 36. SAR1 UNDER CONSTRUCTION, WITH WORKERS ATOP CRANE. EEC print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    36. SAR-1 UNDER CONSTRUCTION, WITH WORKERS ATOP CRANE. EEC print no. N-C-01-00031, no date. Photograph by Benjamin F. Pearson. - Santa Ana River Hydroelectric System, SAR-1 Powerhouse, Redlands, San Bernardino County, CA

  18. 35. SAR1 UNDER CONSTRUCTION, SHOWING TAILRACE AREA AND SCAFFOLDING. EEC ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    35. SAR-1 UNDER CONSTRUCTION, SHOWING TAILRACE AREA AND SCAFFOLDING. EEC print no. N-C-01-00028, no date. Photograph by Benjamin F. Pearson. - Santa Ana River Hydroelectric System, SAR-1 Powerhouse, Redlands, San Bernardino County, CA

  19. 7. SOUTHEAST PENSTOCK ENTERING RECEIVER ON NORTHEAST SIDE OF SAR1, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. SOUTHEAST PENSTOCK ENTERING RECEIVER ON NORTHEAST SIDE OF SAR-1, ALSO SHOWING TURBINE SHUT OFF VALVES AND ISOLATION VALVE. VIEW TO WEST. - Santa Ana River Hydroelectric System, SAR-1 Powerhouse, Redlands, San Bernardino County, CA

  20. 33. SAR1, LOOKING DOWN CANYON OVER TAILRACE CONSTRUCTION. EEC print ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    33. SAR-1, LOOKING DOWN CANYON OVER TAILRACE CONSTRUCTION. EEC print no. G-C-01-00269, no date. Photograph by Benjamin F. Pearson. - Santa Ana River Hydroelectric System, SAR-1 Powerhouse, Redlands, San Bernardino County, CA

  1. 37. SAR2, SHOWING OIL CIRCUIT BREAKERS (ABOVE) AND GENERATOR FIELD ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    37. SAR-2, SHOWING OIL CIRCUIT BREAKERS (ABOVE) AND GENERATOR FIELD COIL CONTROL RHEOSTATS (BELOW). SCE negative no. 10331, November 1, 1923. Photograph by G. Haven Bishop. - Santa Ana River Hydroelectric System, SAR-2 Powerhouse, Redlands, San Bernardino County, CA

  2. 32. SAR1, VIEW FROM STABLE LOFT. SCE negative no. 10319, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    32. SAR-1, VIEW FROM STABLE LOFT. SCE negative no. 10319, November 1, 1923. Photograph by G. Haven Bishop. - Santa Ana River Hydroelectric System, SAR-1 Powerhouse, Redlands, San Bernardino County, CA

  3. 26. SAR2, GENERAL VIEW FROM WEST SHOWING DAMAGE FROM 1938 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. SAR-2, GENERAL VIEW FROM WEST SHOWING DAMAGE FROM 1938 FLOOD. SCE negative no. 20949, March 30, 1938. Photograph by G. Haven Bishop. - Santa Ana River Hydroelectric System, SAR-2 Powerhouse, Redlands, San Bernardino County, CA

  4. 34. SAR2, WATERDRIVEN EXCITERS. SCE negative no. 10329, November 1, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    34. SAR-2, WATER-DRIVEN EXCITERS. SCE negative no. 10329, November 1, 1923. Photograph by G. Haven Bishop. - Santa Ana River Hydroelectric System, SAR-2 Powerhouse, Redlands, San Bernardino County, CA

  5. 31. SAR2, INTERIOR SHOWING SWITCHBOARD, OPERATOR'S DESK, AND TRANSFORMER BANK. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    31. SAR-2, INTERIOR SHOWING SWITCHBOARD, OPERATOR'S DESK, AND TRANSFORMER BANK. SCE negative no. 10327, November 1, 1923. Photograph by G. Haven Bishop. - Santa Ana River Hydroelectric System, SAR-2 Powerhouse, Redlands, San Bernardino County, CA

  6. 1. DOMESTIC WATER SUPPLY TREATMENT HOUSE, ON PENSTOCK ABOVE SAR1. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. DOMESTIC WATER SUPPLY TREATMENT HOUSE, ON PENSTOCK ABOVE SAR-1. VIEW TO NORTWEST. - Santa Ana River Hydroelectric System, SAR-1 Domestic Water Supply Treatment House, Redlands, San Bernardino County, CA

  7. The SARS-Unique Domain (SUD) of SARS Coronavirus Contains Two Macrodomains That Bind G-Quadruplexes

    PubMed Central

    Tan, Jinzhi; Vonrhein, Clemens; Smart, Oliver S.; Bricogne, Gerard; Bollati, Michela; Kusov, Yuri; Hansen, Guido; Mesters, Jeroen R.; Schmidt, Christian L.; Hilgenfeld, Rolf

    2009-01-01

    Since the outbreak of severe acute respiratory syndrome (SARS) in 2003, the three-dimensional structures of several of the replicase/transcriptase components of SARS coronavirus (SARS-CoV), the non-structural proteins (Nsps), have been determined. However, within the large Nsp3 (1922 amino-acid residues), the structure and function of the so-called SARS-unique domain (SUD) have remained elusive. SUD occurs only in SARS-CoV and the highly related viruses found in certain bats, but is absent from all other coronaviruses. Therefore, it has been speculated that it may be involved in the extreme pathogenicity of SARS-CoV, compared to other coronaviruses, most of which cause only mild infections in humans. In order to help elucidate the function of the SUD, we have determined crystal structures of fragment 389–652 (“SUDcore”) of Nsp3, which comprises 264 of the 338 residues of the domain. Both the monoclinic and triclinic crystal forms (2.2 and 2.8 Å resolution, respectively) revealed that SUDcore forms a homodimer. Each monomer consists of two subdomains, SUD-N and SUD-M, with a macrodomain fold similar to the SARS-CoV X-domain. However, in contrast to the latter, SUD fails to bind ADP-ribose, as determined by zone-interference gel electrophoresis. Instead, the entire SUDcore as well as its individual subdomains interact with oligonucleotides known to form G-quadruplexes. This includes oligodeoxy- as well as oligoribonucleotides. Mutations of selected lysine residues on the surface of the SUD-N subdomain lead to reduction of G-quadruplex binding, whereas mutations in the SUD-M subdomain abolish it. As there is no evidence for Nsp3 entering the nucleus of the host cell, the SARS-CoV genomic RNA or host-cell mRNA containing long G-stretches may be targets of SUD. The SARS-CoV genome is devoid of G-stretches longer than 5–6 nucleotides, but more extended G-stretches are found in the 3′-nontranslated regions of mRNAs coding for certain host-cell proteins involved

  8. SweepSAR: Beam-forming on Receive Using a Reflector-Phased Array Feed Combination for Spaceborne SAR

    NASA Technical Reports Server (NTRS)

    Freeman, A.; Krieger, G.; Rosen, P.; Younis, M.; Johnson, W. T. K.; Huber, S.; Jordan, R.; Moreira, A.

    2012-01-01

    In this paper, an alternative approach is described that is suited for longer wavelength SARs in particular, employing a large, deployable reflector antenna and a much simpler phased array feed. To illuminate a wide swath, a substantial fraction of the phased array feed is excited on transmit to sub-illuminate the reflector. Shorter transmit pulses are required than for conventional SAR. On receive, a much smaller portion of the phased array feed is used to collect the return echo, so that a greater portion of the reflector antenna area is used. The locus of the portion of the phased array used on receive is adjusted using an analog beam steering network, to 'sweep' the receive beam(s) across the illuminated swath, tracking the return echo. This is similar in some respects to the whiskbroom approach to optical sensors, hence the name: SweepSAR.SweepSAR has advantages over conventional SAR in that it requires less transmit power, and if the receive beam is narrow enough, it is relatively immune to range ambiguities. Compared to direct radiating arrays with digital beam- forming, it is much simpler to implement, uses currently available technologies, is better suited for longer wavelength systems, and does not require extremely high data rates or onboard processing.

  9. Polar format algorithm for SAR imaging with Matlab

    NASA Astrophysics Data System (ADS)

    Deming, Ross; Best, Matthew; Farrell, Sean

    2014-06-01

    Due to its computational efficiency, the polar format algorithm (PFA) is considered by many to be the workhorse for airborne synthetic aperture radar (SAR) imaging. PFA is implemented in spatial Fourier space, also known as "K-space", which is a convenient domain for understanding SAR performance metrics, sampling requirements, etc. In this paper the mathematics behind PFA are explained and computed examples are presented, both using simulated data, and experimental airborne radar data from the Air Force Research Laboratory (AFRL) Gotcha Challenge collect. In addition, a simple graphical method is described that can be used to model and predict wavefront curvature artifacts in PFA imagery, which are due to the limited validity of the underlying far-field approximation. The appendix includes Matlab code for computing SAR images using PFA.

  10. Parallel algorithms for high-speed SAR processing

    NASA Astrophysics Data System (ADS)

    Mallorqui, Jordi J.; Bara, Marc; Broquetas, Antoni; Wis, Mariano; Martinez, Antonio; Nogueira, Leonardo; Moreno, Victoriano

    1998-11-01

    The mass production of SAR products and its usage on monitoring emergency situations (oil spill detection, floods, etc.) requires high-speed SAR processors. Two different parallel strategies for near real time SAR processing based on a multiblock version of the Chirp Scaling Algorithm (CSA) have been studied. The first one is useful for small companies that would like to reduce computation times with no extra investment. It uses a cluster of heterogeneous UNIX workstations as a parallel computer. The second one is oriented to institutions, which have to process large amounts of data in short times and can afford the cost of large parallel computers. The parallel programming has reduced in both cases the computational times when compared with the sequential versions.

  11. Ensemble polarimetric SAR image classification based on contextual sparse representation

    NASA Astrophysics Data System (ADS)

    Zhang, Lamei; Wang, Xiao; Zou, Bin; Qiao, Zhijun

    2016-05-01

    Polarimetric SAR image interpretation has become one of the most interesting topics, in which the construction of the reasonable and effective technique of image classification is of key importance. Sparse representation represents the data using the most succinct sparse atoms of the over-complete dictionary and the advantages of sparse representation also have been confirmed in the field of PolSAR classification. However, it is not perfect, like the ordinary classifier, at different aspects. So ensemble learning is introduced to improve the issue, which makes a plurality of different learners training and obtained the integrated results by combining the individual learner to get more accurate and ideal learning results. Therefore, this paper presents a polarimetric SAR image classification method based on the ensemble learning of sparse representation to achieve the optimal classification.

  12. Polarimetric SAR Models for Oil Fields Monitoring in China Seas

    NASA Astrophysics Data System (ADS)

    Buono, A.; Nunziata, F.; Li, X.; Wei, Y.; Ding, X.

    2014-11-01

    In this study, physical-based models for polarimetric Synthetic Aperture Radar (SAR) oil fields monitoring are proposed. They all share a physical rationale relying on the different scattering mechanisms that characterize a free sea surface, an oil slick-covered sea surface, and a metallic target. In fact, sea surface scattering is well modeled by a Bragg-like behaviour, while a strong departure from Bragg scattering is in place when dealing with oil slicks and targets. Furthermore, the proposed polarimetric models aim at addressing simultaneously target and oil slick detection, providing useful extra information with respect to single-pol SAR data in order to approach oil discrimination and classification. Experiments undertaken over East and South China Sea from actual C-band RadarSAT-2 full-pol SAR data witness the soundness of the proposed rationale.

  13. Metamaterial-Embedded Low SAR PIFA for Cellular Phone.

    PubMed

    Faruque, M R I; Hossain, M I; Misran, N; Singh, M; Islam, M T

    2015-01-01

    A metamaterial-embedded planar inverted-F antenna (PIFA) is proposed in this study for cellular phone applications. A dual-band PIFA is designed to operate both GSM 900 MHz and DCS 1800 MHz. The ground plane of a conventional PIFA is modified using a planar one-dimensional metamaterial array. The investigation is performed using the Finite Integration Technique (FIT) of CST Microwave Studio. The performance of the developed antenna was measured in an anechoic chamber. The specific absorption rate (SAR) values are calculated considering two different holding positions: cheek and tilt. The SAR values are measured using COMOSAR measurement system. Good agreement is observed between the simulated and measured data. The results indicate that the proposed metamaterial-embedded antenna produces significantly lower SAR in the human head compared to the conventional PIFA. Moreover, the modified antenna substrate leads to slight improvement of the antenna performances. PMID:26599584

  14. SAR coherent change detection (CCD) for search and rescue

    NASA Astrophysics Data System (ADS)

    Mansfield, Arthur W.; Poehler, Paul L.; Rais, Houra

    1997-06-01

    Recent advances in the areas of phase history processing, interferometry, and radargrammetric adjustment have made possible extremely accurate information extraction from synthetic aperture radar (SAR) image pairs by means of interferometric techniques. The potential gain in accuracy is significant since measurements can theoretically be determined to within a fraction of a wavelength (subcentimeter accuracy) as opposed to a fraction of pixel distance (meter accuracy). One promising application of interferometric SAR (IFSAR) is the use of coherent change detection (CCD) over large areas to locate downed aircraft. This application poses an additional challenge since IFSAR must be processed at longer wavelengths to achieve foliage penetration. In this paper a combination of advanced techniques is described for using airborne SAR imagery to carry out this mission. Performance parameters are derived, and some examples are given from actual data.

  15. Simulation of bit-quantization influence on SAR-images

    NASA Astrophysics Data System (ADS)

    Wolframm, A. P.; Pike, T. K.

    The first European Remote Sensing satellite ERS-1 has two imaging modes, the conventional Synthetic Aperture Radar (SAR) mode and the wave mode. Two quantization schemes, 2-bit and 4-bit, have been proposed for the analogue-to-digital conversion of the video signal of the ERS-1 wave mode. This paper analyzes the influence of these two quantization schemes on ocean-wave spectra. The SAR-images were obtained through simulation using a static oceanwave radar model and a comprehensive software SAR-system simulation model (SARSIM) on the DFVLR computing system. The results indicate that spectra produced by the 4-bit quantization are not significantly degraded from the optimum, but that the 2-bit quantization requires some gain adjustment for optimal spectral reproduction. The conclusions are supported by images and spectral plots covering the various options simulated.

  16. SAR data processing for the Magellan prime mission

    NASA Technical Reports Server (NTRS)

    Leung, K.; Jin, M.; Wong, C.; Gilbert, J.

    1992-01-01

    The Magellan prime mission involves mapping the planet of Venus once around its rotational axis. The Magellan synthetic aperture radar (SAR) data processing facility processes all SAR data collected by the Magellan spacecraft into image data on an orbit-by-orbit basis. About 1700 million bits of radar data were collected. A complete description of the Magellan SAR Data Processing Facility is provided with emphasis on key design features of the data processors that satisfied the project data processing requirements. A summary of the attained data processing performance is included, as well as a brief discussion of some of the constraints and considerations regarding the applicability of the processors to meeting the data processing goals anticipated for the follow-on mission phases (i.e., cycles II, III, and beyond).

  17. 3-D Target Location from Stereoscopic SAR Images

    SciTech Connect

    DOERRY,ARMIN W.

    1999-10-01

    SAR range-Doppler images are inherently 2-dimensional. Targets with a height offset lay over onto offset range and azimuth locations. Just which image locations are laid upon depends on the imaging geometry, including depression angle, squint angle, and target bearing. This is the well known layover phenomenon. Images formed with different aperture geometries will exhibit different layover characteristics. These differences can be exploited to ascertain target height information, in a stereoscopic manner. Depending on the imaging geometries, height accuracy can be on the order of horizontal position accuracies, thereby rivaling the best IFSAR capabilities in fine resolution SAR images. All that is required for this to work are two distinct passes with suitably different geometries from any plain old SAR.

  18. Nonlinear apodization for sidelobe control in SAR imagery

    NASA Astrophysics Data System (ADS)

    Stankwitz, H. C.; Dallaire, R. J.; Fienup, J. R.

    1995-01-01

    Synthetic aperture radar (SAR) imagery often requires sidelobe control, or apodization, via weighting of the frequency domain aperture. This is of particular importance when imaging scenes containing objects such as ships or buildings having very large radar cross sections. Sidelobe improvement using spectral weighting is invariably at the expense of mainlobe resolution. Presented here is a class of nonlinear operators which significantly reduce sidelobe levels without degrading mainlobe resolution. Implementation is via sequential nonlinear operations applied to complex-valued (undetected) SAR imagery. SAR imaging is used to motivate the concepts developed in this work. However, these nonlinear apodization techniques have potentially broad and far-ranging applications in antenna design, sonar, digital filtering, etc., i.e., whenever data can be represented as the Fourier transform of a finite-aperture signal.

  19. Radiometric correction of SAR images of varying terrain heights

    NASA Technical Reports Server (NTRS)

    Freeman, A.; Moghaddam, M.; Zink, M.; Zebker, H.

    1992-01-01

    The advantages and disadvantages of three different approaches to solving the problem of the radiometric correction of synthetic aperture radar (SAR) images of varying terrain heights are presented. The first approach involves registration of a digital elevation model (DEM) of the terrain to the image, determination of the local elevation and incidence angles, and appropriate radiometric correction. The second approach uses a DEM generated from interferometric SAR data to derive the elevation and incidence angle maps. In the third approach, a monopulse technique is employed to determine the elevation angle only. The relative errors in radiometric correction between these approaches are assessed. Calibration errors are estimated using corner reflectors deployed within some of the scenes imaged by the Jet Propulsion Laboratory airborne SAR (JPL AIRSAR).

  20. Metamaterial-Embedded Low SAR PIFA for Cellular Phone

    PubMed Central

    Faruque, M. R. I.; Hossain, M. I.; Misran, N.; Singh, M.; Islam, M. T.

    2015-01-01

    A metamaterial-embedded planar inverted-F antenna (PIFA) is proposed in this study for cellular phone applications. A dual-band PIFA is designed to operate both GSM 900 MHz and DCS 1800 MHz. The ground plane of a conventional PIFA is modified using a planar one-dimensional metamaterial array. The investigation is performed using the Finite Integration Technique (FIT) of CST Microwave Studio. The performance of the developed antenna was measured in an anechoic chamber. The specific absorption rate (SAR) values are calculated considering two different holding positions: cheek and tilt. The SAR values are measured using COMOSAR measurement system. Good agreement is observed between the simulated and measured data. The results indicate that the proposed metamaterial-embedded antenna produces significantly lower SAR in the human head compared to the conventional PIFA. Moreover, the modified antenna substrate leads to slight improvement of the antenna performances. PMID:26599584

  1. SAR target classification based on multiscale sparse representation

    NASA Astrophysics Data System (ADS)

    Ruan, Huaiyu; Zhang, Rong; Li, Jingge; Zhan, Yibing

    2016-03-01

    We propose a novel multiscale sparse representation approach for SAR target classification. It firstly extracts the dense SIFT descriptors on multiple scales, then trains a global multiscale dictionary by sparse coding algorithm. After obtaining the sparse representation, the method applies spatial pyramid matching (SPM) and max pooling to summarize the features for each image. The proposed method can provide more information and descriptive ability than single-scale ones. Moreover, it costs less extra computation than existing multiscale methods which compute a dictionary for each scale. The MSTAR database and ship database collected from TerraSAR-X images are used in classification setup. Results show that the best overall classification rate of the proposed approach can achieve 98.83% on the MSTAR database and 92.67% on the TerraSAR-X ship database.

  2. SAR imaging for a forward-looking GPR system

    NASA Astrophysics Data System (ADS)

    Liu, Guoqing; Wang, Yanwei; Li, Jian; Bradley, Marshall R.

    2003-09-01

    We investigate both two-dimensional (2-D) and three-dimensional (3-D) synthetic aperture radar (SAR) imaging techniques for a forward-looking ground penetrating radar (FLGPR) system. In particular, we consider SAR imaging using the delay-and-sum (DAS), phase-shift migration, and spectral estimation (joint APES (Amplitude and Phase EStimation) and RCB (Robust Capon Beamforming)) approaches with the PSI (Planning Systems Inc.) FLGPR Phase II system. For the DAS and phase-shift migration approaches, we use shading in both frequency and cross-track aperture dimensions to reduce sidelobe leakages and clutter. We perform both coherent and non-coherent multi-look processing as well as smoothing to improve the SAR imaging quality and landmine detection capability of the system. The effectiveness of the approaches are demonstrated with an experimental data set collected by the PSI FLGPR Phase II system.

  3. Analysis of motion disambiguation using multi-channel circular SAR

    NASA Astrophysics Data System (ADS)

    Fasih, Ahmed R.; Rossler, Carl W.; Ash, Joshua N.; Moses, Randolph L.

    2010-04-01

    Combining moving target indication (MTI) radar with synthetic aperture radar (SAR) is of great interest to radar specialists, in terms of improving multiple-target tracking in large, urban scenes. A major obstacle to such a merger are ambiguities induced by mution. Using statistical bounds we quantify the improvement of moving target localization with multi-channel SAR over single-channel SAR and the more traditional MTI technique of displaced phase center array (DPCA) processing. We show that the potential for substantial improvements in localization performance is borne out by practical estimators based on sparse reconstruction algorithms, whose performance approach statistical bounds, even under clutter. We also outline a parallelization scheme for the nonquadratic regularized sparse reconstruction technique to utilize clusters for processing large datasets.

  4. Unsupervised Change Detection in SAR Images Using Gaussian Mixture Models

    NASA Astrophysics Data System (ADS)

    Kiana, E.; Homayouni, S.; Sharifi, M. A.; Farid-Rohani, M.

    2015-12-01

    In this paper, we propose a method for unsupervised change detection in Remote Sensing Synthetic Aperture Radar (SAR) images. This method is based on the mixture modelling of the histogram of difference image. In this process, the difference image is classified into three classes; negative change class, positive change class and no change class. However the SAR images suffer from speckle noise, the proposed method is able to map the changes without speckle filtering. To evaluate the performance of this method, two dates of SAR data acquired by Uninhabited Aerial Vehicle Synthetic from an agriculture area are used. Change detection results show better efficiency when compared to the state-of-the-art methods.

  5. SAR Imagery Segmentation by Statistical Region Growing and Hierarchical Merging

    SciTech Connect

    Ushizima, Daniela Mayumi; Carvalho, E.A.; Medeiros, F.N.S.; Martins, C.I.O.; Marques, R.C.P.; Oliveira, I.N.S.

    2010-05-22

    This paper presents an approach to accomplish synthetic aperture radar (SAR) image segmentation, which are corrupted by speckle noise. Some ordinary segmentation techniques may require speckle filtering previously. Our approach performs radar image segmentation using the original noisy pixels as input data, eliminating preprocessing steps, an advantage over most of the current methods. The algorithm comprises a statistical region growing procedure combined with hierarchical region merging to extract regions of interest from SAR images. The region growing step over-segments the input image to enable region aggregation by employing a combination of the Kolmogorov-Smirnov (KS) test with a hierarchical stepwise optimization (HSWO) algorithm for the process coordination. We have tested and assessed the proposed technique on artificially speckled image and real SAR data containing different types of targets.

  6. Modelling Iteration Convergence Condition for Single SAR Image Geocoding

    NASA Astrophysics Data System (ADS)

    Dong, Yuting; Liao, Minghsheng; Zhang, Lu; Shi, Xuguo

    2014-11-01

    Single SAR image geocoding is to determine the ground coordinate for each pixel in the SAR image assisted with an external DEM. Due to the uncertainty of the elevation of each pixel in SAR image, an iterative procedure is needed, which suffers from the problem of divergence in some difficult areas such as shaded and serious layover areas. This paper aims at theoretically analysing the convergence conditions that has not been intensively studied till now. To make the discussion easier, the Range-Doppler (RD) model is simplified and then the general surface is simplified into a planar surface. Mathematical deduction is carried out to derive the convergence conditions and the impact factors for the convergence speed are analysed. The theoretical findings are validated by experiments for both simulated and real surfaces.

  7. Theory and measure of certain image norms in SAR

    NASA Technical Reports Server (NTRS)

    Raney, R. K.

    1984-01-01

    The principal properties of synthetic aperture radar SAR imagery of point and distributed objects are summarized. Against this background, the response of a SAR (Synthetic Aperture Radar) to the moving surface of the sea is considered. Certain conclusions are drawn as to the mechanism of interaction between microwaves and the sea surface. Focus and speckle spectral tests may be used on selected SAR imagery for areas of the ocean. The fine structure of the sea imagery is sensitive to processor focus and adjustment. The ocean reflectivity mechanism must include point like scatterers of sufficient radar cross section to dominate the return from certain individual resolution elements. Both specular and diffuse scattering mechanisms are observed together, to varying degree. The effect is sea state dependent. Several experiments are proposed based on imaging theory that could assist in the investigation of reflectivity mechanisms.

  8. Nonlocal means SAR image despeckling using Principle Neighborhood Dictionaries

    NASA Astrophysics Data System (ADS)

    Zhong, Hua; Yang, Chen; Jiao, L. C.

    2011-11-01

    The Principle Neighborhood Dictionary (PND) filter projects the image patches onto a lower dimensional subspace using Principle Component analysis (PCA), based on which the similarity measure of image patch can be computed with a higher accuracy for the nonlocal means (NLM) algorithm. In this paper, a new PND filter for synthetic aperture radar (SAR) image despeckling is presented, in which a new distance that adapts to the multiplicative speckle noise is derived. Compared with the commonly used Euclidean distance in NLM, the new distance measure improves the accuracy of the similarity measure of speckled patches in SAR images. The proposed method is validated on simulated and real SAR images through comparisons with other classical despeckling methods.

  9. Sparsity-driven autofocus for multipass SAR tomography

    NASA Astrophysics Data System (ADS)

    Muirhead, F.; Mulgrew, B.; Woodhouse, I. H.; Greig, D.

    2015-10-01

    Synthetic aperture radar (SAR) systems produce high resolution, two dimensional imaging of areas of environmental interest. SAR interferometry and tomography enables these techniques to extend to three dimensional imaging by exploiting multiple SAR images with diversity in space and time. These techniques require accurate phase information over multiple images as the data is extremely sensitive to deviations from the reference track, therefore to enable interferometry and tomography an accurate autofocus solution is required. This paper investigates phase errors resulting from navigational uncertainties in multipass spotlight SAR imaging and uses techniques from the field of compressive sensing to achieve an autofocus solution. The proposed algorithm builds on previous autofocus work by expanding it to the multipass case and jointly recovers phase errors for all images simultaneously, making it extremely useful for interferometry and tomography techniques. The algorithm described uses pixels that are stable in all SAR images to gain an autofocus solution as these are the pixels that are the focus for analysis using tomography. This is unlike conventional autofocus, which just works on an image-by-image basis. The tools of compressive sensing can be used to concurrently select pixels for bright image elements that are stable and coherent over all images, as these pixels are sparse in the image domain, and calculate the phase errors present in each pass. Using the multipass data after autofocus, height distributions for scatterers in single pixels are determined for simulated forest scenes at X-band. The performance of the autofocus algorithm is examined through numerical simulations and is also applied to real data collected from Selex ES's airborne, X-band, experimental SAR system. The experimental results demonstrate that the algorithm effectively achieves an autofocus solution. By finding the vertical distribution of two scatterers in a single pixel over

  10. Modeling SAR images with a generalization of the Rayleigh distribution.

    PubMed

    Kuruoğlu, Ercan E; Zerubia, Josiane

    2004-04-01

    Synthetic aperture radar (SAR) imagery has found important applications due to its clear advantages over optical satellite imagery one of them being able to operate in various weather conditions. However, due to the physics of the radar imaging process, SAR images contain unwanted artifacts in the form of a granular look which is called speckle. The assumptions of the classical SAR image generation model lead to a Rayleigh distribution model for the histogram of the SAR image. However, some experimental data such as images of urban areas show impulsive characteristics that correspond to underlying heavy-tailed distributions, which are clearly non-Rayleigh. Some alternative distributions have been suggested such as the Weibull, log-normal, and the k-distribution which had success in varying degrees depending on the application. Recently, an alternative model namely the alpha-stable distribution has been suggested for modeling radar clutter. In this paper, we show that the amplitude distribution of the complex wave, the real and the imaginery components of which are assumed to be distributed by the alpha-stable distribution, is a generalization of the Rayleigh distribution. We demonstrate that the amplitude distribution is a mixture of Rayleighs as is the k-distribution in accordance with earlier work on modeling SAR images which showed that almost all successful SAR image models could be expressed as mixtures of Rayleighs. We also present parameter estimation techniques based on negative order moments for the new model. Finally, we test the performance of the model on urban images and compare with other models such as Rayleigh, Weibull, and the k-distribution. PMID:15376587

  11. Multi-frequency, polarimetric SAR analysis for archaeological prospection

    NASA Astrophysics Data System (ADS)

    Stewart, Christopher; Lasaponara, Rosa; Schiavon, Giovanni

    2014-05-01

    The aim of this study is to assess the sensitivity to buried archaeological structures of C- and L-band Synthetic Aperture Radar (SAR) in various polarisations. In particular, single and dual polarised data from the Phased Array type L-band SAR (PALSAR) sensor on-board the Advanced Land Observing Satellite (ALOS) is used, together with quadruple polarised (quad pol) data from the SAR sensor on Radarsat-2. The study region includes an isolated area of open fields in the eastern outskirts of Rome where buried structures are documented to exist. Processing of the SAR data involved multitemporal averaging, analysis of target decompositions, study of the polarimetric signatures over areas of suspected buried structures and changes of the polarimetric bases in an attempt to enhance their visibility. Various ancillary datasets were obtained for the analysis, including geological and lithological charts, meteorological data, Digital Elevation Models (DEMs), optical imagery and an archaeological chart. For the Radarsat-2 data analysis, results show that the technique of identifying the polarimetric bases that yield greatest backscatter over anomaly features, and subsequently changing the polarimetric bases of the time series, succeeded in highlighting features of interest in the study area. It appeared possible that some of the features could correspond with structures documented on the reference archaeological chart, but there was not a clear match between the chart and the results of the Radarsat-2 analysis. A similar conclusion was reached for the PALSAR data analysis. For the PALSAR data, the volcanic nature of the soil may have hindered the visibility of traces of buried features. Given the limitations of the accuracy of the archaeological chart and the spatial resolution of both the SAR datasets, further validation would be required to draw any precise conclusions on the sensitivity of the SAR data to buried structures. Such a validation could include geophysical

  12. The phase transition method for SAR measurement in MRI

    NASA Astrophysics Data System (ADS)

    Romano, Rocco; Acernese, Fausto; Vilasi, Silvia; Barone, Fabrizio

    2010-03-01

    During an MR procedure, the patient absorbs a portion of the transmitted RF energy, which may result in tissue heating and other adverse effects, such as alterations in visual, auditory and neural functions. The Specific Absorption Rate (SAR), in W/kg, is the RF power absorbed per unit mass of tissue and is one of the most important parameters related with thermal effects and acts as a guideline for MRI safety. Strict limits to the SAR levels are imposed by patient safety international regulations (CEI - EN 60601 - 2 - 33) and SAR measurements are required in order to verify its respect. The recommended methods for mean SAR measurement are quite problematic and often require a maintenance man intervention and long stop machine. For example, in the CEI recommended pulse energy method, the presence of a maintenance man is required in order to correctly connect the required instrumentation; furthermore, the procedure is complex and requires remarkable processing and calculus. Simpler are the calorimetric methods, also if in this case long acquisition times are required in order to have significant temperature variations and accurate heat capacity knowledge (CEI - EN 60601 - 2 - 33). The phase transition method is a new method to measure SAR in MRI which has the advantages to be very simple and to overcome all the typical calorimetric method problems. It does not require in gantry temperature measurements, any specific heat or heat capacity knowledge, but only mass and time measurement. On the other hand, it is necessary to establish if all deposited power SAR can be considered acquired and measured. In this paper, that will be shown.

  13. The phase transition method for SAR measurement in MRI

    NASA Astrophysics Data System (ADS)

    Romano, R.; Canonico, R.; Acernese, F.; Giordano, G.; Barone, F.

    2014-03-01

    During an MR procedure, the patient absorbs a portion of the transmitted RF energy, which may result in tissue heating and other adverse effects, such as alterations in visual, auditory and neural functions. The Specific Absorption Rate (SAR), in W/kg, is the RF power absorbed per unit mass of tissue and is one of the most important parameters related with thermal effects and acts as a guideline for MRI safety. Strict limits to the SAR levels are imposed by patient safety international regulations (CEI - EN 60601 - 2 - 33) and SAR measurements are required in order to verify its respect. The recommended methods for mean SAR measurement are quite problematic and often require a maintenance man intervention and long stop machine. For example, in the CEI recommended pulse energy method, the presence of a maintenance man is required in order to correctly connect the required instrumentation; furthermore, the procedure is complex and requires remarkable processing and calculus. Simpler are the calorimetric methods, also if in this case long acquisition times are required in order to have significant temperature variations and accurate heat capacity knowledge (CEI - EN 60601 - 2 - 33). The phase transition method is a new method to measure SAR in MRI which has the advantages to be very simple and to overcome all the typical calorimetric method problems. It does not require in gantry temperature measurements, any specific heat or heat capacity knowledge, but only mass and time measurement. Nevertheless, in order to consider this method it is necessary to verify that all deposited SAR power can be considered acquired and measured. In this paper considerations about this aspect are conducted.

  14. A no-calorimetric method for measuring SAR in MRI

    NASA Astrophysics Data System (ADS)

    Romano, Rocco; Acernese, Fausto; Barone, Fabrizio

    2011-04-01

    During an MR procedure, the patient absorbs a portion of the transmitted RF energy, which may result in tissue heating and other adverse effects, such as alterations in visual, auditory and neural functions. The Specific Absorption Rate (SAR), in W/kg, is the RF power absorbed per unit mass of tissue and is one of the most important parameters related with thermal effects and acts as a guideline for MRI safety. Strict limits to the SAR levels are imposed by patient safety international regulations (CEI - EN 60601 - 2 - 33) and SAR measurements are required in order to verify its respect. The recommended methods for mean SAR measurement are quite problematic and often require a maintenance man intervention and long stop machine. For example, in the CEI recommended pulse energy method, the presence of a maintenance man is required in order to correctly connect the required instrumentation; furthermore, the procedure is complex and requires remarkable processing and calculus. Simpler are the calorimetric methods, also if in this case long acquisition times are required in order to have significant temperature variations and accurate heat capacity knowledge (CEI - EN 60601 - 2 - 33). The phase transition method is a new no-calorimetric method to measure SAR in MRI which has the advantages to be very simple and to overcome all the typical calorimetric method problems. It does not require in gantry temperature measurements, any specific heat or heat capacity knowledge, but only mass and time measurement. On the other hand, it is necessary to establish if all deposited power SAR can be considered acquired and measured. In this paper, that will be shown.

  15. Optical and SAR data integration for automatic change pattern detection

    NASA Astrophysics Data System (ADS)

    Mishra, B.; Susaki, J.

    2014-09-01

    Automatic change pattern mapping in urban and sub-urban area is important but challenging due to the diversity of urban land use pattern. With multi-sensor imagery, it is possible to generate multidimensional unique information of Earth surface features that allow developing a relationship between a response of each feature to synthetic aperture radar (SAR) and optical sensors to track the change automatically. Thus, a SAR and optical data integration framework for change detection and a relationship for automatic change pattern detection were developed. It was carried out in three steps: (i) Computation of indicators from SAR and optical images, namely: normalized difference ratio (NDR) from multi-temporal SAR images and the normalized difference vegetation index difference (NDVI) from multi-temporal optical images, (ii) computing the change magnitude image from NDR and ΔNDVI and delineating the change area and (iii) the development of an empirical relationship, for automatic change pattern detection. The experiment was carried out in an outskirts part of Ho Chi Minh City, one of the fastest growing cities in the world. The empirical relationship between the response of surface feature to optical and SAR imagery has successfully delineated six changed classes in a very complex urban sprawl area that was otherwise impossible with multi-spectral imagery. The improvement of the change detection results by making use of the unique information on both sensors, optical and SAR, is also noticeable with a visual inspection and the kappa index was increased by 0.13 (0.75 to 0.88) in comparison to only optical images.

  16. Surface deformation of Taipei basin detected by Differential SAR Interferometry

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Chang, C.; Yen, J.; Lin, M.

    2006-12-01

    Taiwan island is located between the southeastern periphery of the Eurasian plate and the Philippine Sea plate. The two converging plates produced very active tectonics, and can be seen by the high seismicity and deformation rate. Taipei, the highest populated area, center of politics, and economics in Taiwan, is in Taipei basin at the northern part of the island. There are several faults in and surrounding the basin, and the city is threatened with a high geological hazard potential that we should keep monitoring the crustal deformation to prevent and mitigate the disaster effect. The aims of our study is to apply the DInSAR technique to determine the surface deformation of Taipei basin area, and discussing the relation between the manifestation of deformation and the tectonically active region, Shanjiao fault. In the past few years, Differential SAR Interferometry (DInSAR) has been proved to be a powerful technique for monitoring the neotectonic activities and natural hazards. High spatial sampling rate of DInSAR technique allows studies of surface deformations with centimeter accuracy. In this area, we used ERS-1/2 SAR images acquired from 1993 to 2005 to generate 10 differential interferograms and processed the data using DIAPASON developed by CNES and SRTM global DEM.From our results, the deformation rate in Taipei is generally high in the western end of the basin along the Shanjiao fault and decrease eastward, while the subsidence center often appeared in the center of the Taipei basin. The neotectonic activity of the Shanjiao fault appeared to be insignificant by itself but it seemed to separate the subsiding basin from the surrounding areas. Further comparison between our DInSAR results and isopach of the Taipei basin revealed that the subsidence centers appeared in the interferograms did not coincide with the location where the sediments are thickest. Our results from differential interferometry will be compared to other geodetic measurements such as the

  17. A Support Group for Home-Quarantined College Students Exposed to SARS: Learning from Practice

    ERIC Educational Resources Information Center

    Pan, Peter J. D.; Chang, Shih-Hua; Yu, Yen-Yen

    2005-01-01

    This article is an initial description of a meaningful and valuable clinical experience in interacting with SARS home-quarantined college students in a support group in Taiwan. Information about SARS and home quarantine, the tasks of the Counseling Centers and group work after the SARS outbreak, the support group for home-quarantined members, the…

  18. Fear of Severe Acute Respiratory Syndrome (SARS) among Health Care Workers

    ERIC Educational Resources Information Center

    Ho, Samuel M. Y.; Kwong-Lo, Rosalie S. Y.; Mak, Christine W. Y.; Wong, Joe S.

    2005-01-01

    In this study, the authors examined fear related to severe acute respiratory syndrome (SARS) among 2 samples of hospital staff in Hong Kong. Sample 1 included health care workers (n = 82) and was assessed during the peak of the SARS epidemic. Sample 2 included hospital staff who recovered from SARS (n = 97). The results show that participants in…

  19. 76 FR 8847 - Proposed Information Collection (Lenders Staff Appraisal Reviewer (SAR) Application) Activity...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-15

    ... AFFAIRS Proposed Information Collection (Lenders Staff Appraisal Reviewer (SAR) Application) Activity...: Lenders Staff Appraisal Reviewer (SAR) Application, VA Form 26-0785. OMB Control Number: 2900-0658. Type... lenders to nominate employees for approval as approved Staff Appraisal Reviewer (SAR). Once approved,...

  20. Picture processing of SAR L-band imagery

    NASA Technical Reports Server (NTRS)

    Bryan, M. L.; Stromberg, W. D.; Farr, T.

    1977-01-01

    Data digitization and thresholding are applied to two scenes - sea ice and fresh-water lakes - to define the possible uses of automatic picture processing of uncalibrated SAR L-band imagery. It is shown that certain types of features, those which have constant returns which are also very high or very low in intensity can be effectively studied using simple automatic picture processing techniques applied to uncalibrated radar data. In areas which are generally inaccessible or in which monitoring of the changes of some types of earth surfaces are required, the uncalibrated SAR data can provide valuable inputs for modeling and mapping purposes.

  1. Marine Targets Classification in PolInSAR Data

    NASA Astrophysics Data System (ADS)

    Chen, Peng; Yang, Jingsong; Ren, Lin

    2014-11-01

    In this paper, marine stationary targets and moving targets are studied by Pol-In-SAR data of Radarsat-2. A new method of stationary targets detection is proposed. The method get the correlation coefficient image of the In-SAR data, and using the histogram of correlation coefficient image. Then, A Constant False Alarm Rate (CFAR) algorithm and The Probabilistic Neural Network model are imported to detect stationary targets. To find the moving targets, Azimuth Ambiguity is show as an important feature. We use the length of azimuth ambiguity to get the target's moving direction and speed. Make further efforts, Targets classification is studied by rebuild the surface elevation of marine targets.

  2. Performance evaluation of the JPL interim digital SAR processor

    NASA Technical Reports Server (NTRS)

    Wu, C.; Barkan, B.; Curlander, J.; Jin, M.; Pang, S.

    1983-01-01

    The performance of the Interim Digital SAR Processor (IDP) was evaluated. The IDP processor was originally developed for experimental processing of digital SEASAT SAR data. One phase of the system upgrade which features parallel processing in three peripheral array processors, automated estimation for Doppler parameters, and unsupervised image pixel location determination and registration was executed. The method to compensate for the target range curvature effect was improved. A four point interpolation scheme is implemented to replace the nearest neighbor scheme used in the original IDP. The processor still maintains its fast throughput speed. The current performance and capability of the processing modes now available on the IDP system are updated.

  3. Lithologic mapping in a sedimentary environment using multipolarization SAR images

    NASA Technical Reports Server (NTRS)

    Evans, D. L.; Schenck, L. R.

    1985-01-01

    Multipolarization Synthetic Aperture Radar (SAR) data from the NASA/JPL aircraft SAR were used in conjunction with LANDSAT Thematic Mapper (TM), Thermal Infrared Multispectral Scanner (TIMS), and Airborne Imaging Spectrometer (AIS) data as part of a three-year research program to evaluate the utility of remote sensing measurements for analysis of sedimentary basins. The purpose of this research effort is to construct stratigraphic columns, map variations in the lithology, geometry, and structure of sedimentary rocks in the Wind River/Bighorn Basin area, Wyoming, and to integrate remote sensing data with conventional rain models of basin formation and evolution.

  4. Ultrawideband SAR signature investigations based on electromagnetic models and measurements

    NASA Astrophysics Data System (ADS)

    Lee, Check F.; Binder, Bradley T.

    1995-06-01

    The performance of an electric field integral equation (EFIE) model is discussed in the context of target detection and classification. This EFIE model, which is a modified version of the Finite Element Radiation model developed at MIT Lincoln Laboratory, was used to simulate VHF SAR signatures of ground targets. These SAR signatures were studied and compared with signatures generated from data colelcted by the CARABAS sensor during a 1993 Foliage Penetration Radar experiment. It was found that the EFIE model can provide adequate RCS values and distributions for gound target detection studies. It was also found that the simulated images have reasonable spatial appearance and may be useful for ground target classification studies.

  5. Software For Tie-Point Registration Of SAR Data

    NASA Technical Reports Server (NTRS)

    Rignot, Eric; Dubois, Pascale; Okonek, Sharon; Van Zyl, Jacob; Burnette, Fred; Borgeaud, Maurice

    1995-01-01

    SAR-REG software package registers synthetic-aperture-radar (SAR) image data to common reference frame based on manual tie-pointing. Image data can be in binary, integer, floating-point, or AIRSAR compressed format. For example, with map of soil characteristics, vegetation map, digital elevation map, or SPOT multispectral image, as long as user can generate binary image to be used by tie-pointing routine and data are available in one of the previously mentioned formats. Written in FORTRAN 77.

  6. Robust SAR ATR via set-valued classifiers: new results

    NASA Astrophysics Data System (ADS)

    Hoffman, John R.; Mahler, Ronald P. S.; Ravichandran, Ravi B.; Mehra, Raman K.; Musick, Stanton H.

    2003-08-01

    "Robust identification" in SAR ATR refers to the problem of determining target identity despite the confounding effects of "extended operating conditions" (EOCs). EOC"s are statistically uncharacterizable SAR intensity-signature variations caused by mud, dents, turret articulations, etc. This paper describes a robust ATR approach based on the idea of (1) hedging against EOCs by attaching "random error bars" (random intervals) to each value of the image likelihood function; (2) constructing a "generalized likelihood function" from them; and (3) using a set-valued, MLE-like approach to robustly estimate target type. We compare three such classifiers, showing that they outperform conventional approaches under EOC conditions.

  7. SAR change detection based on intensity and texture changes

    NASA Astrophysics Data System (ADS)

    Gong, Maoguo; Li, Yu; Jiao, Licheng; Jia, Meng; Su, Linzhi

    2014-07-01

    In this paper, a novel change detection approach is proposed for multitemporal synthetic aperture radar (SAR) images. The approach is based on two difference images, which are constructed through intensity and texture information, respectively. In the extraction of the texture differences, robust principal component analysis technique is used to separate irrelevant and noisy elements from Gabor responses. Then graph cuts are improved by a novel energy function based on multivariate generalized Gaussian model for more accurately fitting. The effectiveness of the proposed method is proved by the experiment results obtained on several real SAR images data sets.

  8. Sandia Airspace Recording System (SARS) software reference manual

    SciTech Connect

    Tenney, J.L.

    1996-04-01

    SARS is a data acquisition system designed to gather and process radar data from aircraft flights. A database of flight trajectories has been developed for Albuquerque, NM, and Amarillo, TX. The data is used for safety analysis and risk assessment reports. To support this database effort, Sandia developed a collection of hardware and software tools to collect and post process the aircraft radar data. This document describes the data reduction tools which comprise the SARS, and maintenance procedures for the hardware and software system.

  9. Use of SAR data to study active volcanoes in Alaska

    USGS Publications Warehouse

    Dean, K.G.; Engle, K.; Lu, Zhiming; Eichelberger, J.; Near, T.; Doukas, M.

    1996-01-01

    Synthetic Aperture Radar (SAR) data of the Westdahl, Veniaminof, and Novarupta volcanoes in the Aleutian Arc of Alaska were analysed to investigate recent surface volcanic processes. These studies support ongoing monitoring and research by the Alaska Volcano Observatory (AVO) in the North Pacific Ocean Region. Landforms and possible crustal deformation before, during, or after eruptions were detected and analysed using data from the European Remote Sensing Satellites (ERS), the Japanese Earth Resources Satellite (JERS) and the US Seasat platforms. Field observations collected by scientists from the AVO were used to verify the results from the analysis of SAR data.

  10. Design of a monopulse SAR system to determine elevation angles

    NASA Technical Reports Server (NTRS)

    Oettl, H.; Zink, M.; Zeller, K. H.; Freeman, A.

    1992-01-01

    Terrain height variations in mountainous areas cause problems in radiometric corrections of synthetic aperture radar (SAR) images. To determine the elevation angle and the height at the different parts of an image, an application of the monopulse principle is proposed. From the ratios of images radiometrically modulated by the difference and sum antenna pattern in range it is possible to calculate the appropriate elevation angle at any point in the image. Design considerations for a corresponding airborne SAR-system are presented, and some estimates of error influences (e.g., ambiguities), expected performance and precision in topographic mapping are given.

  11. Use of SAR data to study active volcanoes in Alaska

    USGS Publications Warehouse

    Dean, K.G.; Engle, K.; Lu, Zhiming; Eichelberger, J.; Neal, T.; Doukas, M.

    1996-01-01

    Synthetic Aperture Radar (SAR) data of Westdahl, Veniaminof, and Novarupta volcanoes in the Aleutian Arc of Alaska were analyzed to investigate recent surface volcanic processes. These studies support ongoing monitoring and research by the Alaska Volcano Observatory (AVO) in the North Pacific Ocean Region. Landforms and possible crustal deformation before, during, or after eruptions were detected and analyzed using data from the European Remote Sensing Satellites (ERS), Japanese Earth Resources Satellite (JERS) and the U. S. Seasat platforms. Field observations collected by scientists from the AVO were used to verify the results from the analysis of SAR data.

  12. Formulae for TAR and SAR calculation for Co-60 beam.

    PubMed

    Tripathi, U B

    1980-04-01

    Tissue-air ratio (TAR) and scatter-air ratio (SAR) are very important concepts in radiation dosimetry. In absence of any analytical relation for computation of these quantities a number of empirical equations have been fitted to experimentally measured data. This paper describes the derivation of analytical formulae from first principles. The resultant equations are very simple and can even be evaluated with the help of a slide rule. The computed values of TAR and SAR agree within 1% with the experimental data of Gupta and Cunningham (1966). PMID:7368231

  13. SAR observations of the Gulf Stream during SWADE

    NASA Technical Reports Server (NTRS)

    Vachon, Paris W.; Liu, Antony K.; Mollo-Christensen, Erik

    1992-01-01

    The Surface Wave Dynamics Experiment (SWADE) has gathered SAR observations of the Gulf Stream that show a change in ocean surface brightness; this may be due to the effects of a change in air-sea temperature difference across the observed edge, where the boundary is defined by warm, quickly flowing Gulf Stream water and cooler, relatively stationary shelf water. The two images discussed indicate the possibility of deepening understanding of Gulf Stream front dynamics by using the abundant spatial data of SAR imagery, in conjunction with more conventional (point-like) data on hydrography and currents.

  14. ScanSAR interferometric processing using existing standard InSAR software for measuring large scale land deformation

    NASA Astrophysics Data System (ADS)

    Liang, Cunren; Zeng, Qiming; Jia, Jianying; Jiao, Jian; Cui, Xi'ai

    2013-02-01

    Scanning synthetic aperture radar (ScanSAR) mode is an efficient way to map large scale geophysical phenomena at low cost. The work presented in this paper is dedicated to ScanSAR interferometric processing and its implementation by making full use of existing standard interferometric synthetic aperture radar (InSAR) software. We first discuss the properties of the ScanSAR signal and its phase-preserved focusing using the full aperture algorithm in terms of interferometry. Then a complete interferometric processing flow is proposed. The standard ScanSAR product is decoded subswath by subswath with burst gaps padded with zero-pulses, followed by a Doppler centroid frequency estimation for each subswath and a polynomial fit of all of the subswaths for the whole scene. The burst synchronization of the interferometric pair is then calculated, and only the synchronized pulses are kept for further interferometric processing. After the complex conjugate multiplication of the interferometric pair, the residual non-integer pulse repetition interval (PRI) part between adjacent bursts caused by zero padding is compensated by resampling using a sinc kernel. The subswath interferograms are then mosaicked, in which a method is proposed to remove the subswath discontinuities in the overlap area. Then the following interferometric processing goes back to the traditional stripmap processing flow. A processor written with C and Fortran languages and controlled by Perl scripts is developed to implement these algorithms and processing flow based on the JPL/Caltech Repeat Orbit Interferometry PACkage (ROI_PAC). Finally, we use the processor to process ScanSAR data from the Envisat and ALOS satellites and obtain large scale deformation maps in the radar line-of-sight (LOS) direction.

  15. Differential geodetic stereo SAR with TerraSAR-X by exploiting small multi-directional radar reflectors

    NASA Astrophysics Data System (ADS)

    Gisinger, Christoph; Willberg, Martin; Balss, Ulrich; Klügel, Thomas; Mähler, Swetlana; Pail, Roland; Eineder, Michael

    2016-07-01

    In this paper, we report on the direct positioning of small multi-directional radar reflectors, so-called octahedrons, with the synthetic aperture radar (SAR) satellite TerraSAR-X. Its highest resolution imaging mode termed staring spotlight enables the use of such octahedron reflectors with a dimension of only half a meter, but still providing backscatter equivalent to 1-2 cm observation error. Four octahedrons were deployed at Wettzell geodetic observatory, and observed by TerraSAR-X with 12 acquisitions in three different geometries. By applying our least squares stereo SAR algorithm already tested with common trihedral corner reflectors (CRs), and introducing a novel differential extension using one octahedron as reference point, the coordinates of the remaining octahedrons were directly retrieved in the International Terrestrial Reference Frame (ITRF). Contrary to our standard processing, the differential approach does not require external corrections for the atmospheric path delays and the geodynamic displacements, rendering it particularly useful for joint geodetic networks employing SAR and GNSS. In this paper, we present and discuss both methods based on results when applying them to the aforementioned Wettzell data set of the octahedrons. The comparison with the independently determined reference coordinates confirms the positioning accuracy with 2-5 cm for the standard approach, and 2-3 cm for the differential processing. Moreover, we present statistical uncertainty estimates of the observations and the positioning solutions, which are additionally provided by our parameter estimation algorithms. The results also include our 1.5 m CR available at Wettzell, and the outcomes clearly demonstrate the advantage of the multi-directional octahedrons over conventional CRs for global positioning applications with SAR.

  16. Coastal SAR Altimetry: An Experiment in the Northern Caspian Sea

    NASA Astrophysics Data System (ADS)

    Dinardo, Salvatore; Lucas, Bruno; Benveniste, Jerome

    2013-04-01

    As it has been already shown by previous works (Dinardo et al., 2011, 5th Coastal Altimetry Workshop proceedings), the CryoSat-2 SAR Echoes behave very well in accordance with the waveform physical models even in the very proximity of the coastline in case of favourable conditions (ground-tracks orthogonal to the coastline) whereas they can be still heavily land-contaminated in case the ground-track runs parallel to the coast line. This anisotropic effect is due to the shrinkage of the spatial resolution in SAR mode that occurs just in along-track direction, leaving unchanged the across-track resolution. As a consequence of this footprint shrinkage, the advent of SAR Mode promises to revolutionize the coastal zone satellite altimetry. Anyway, nowadays, all the current more mature SAR Re-tracking methodologies (SAMOSA and CNES/CLS CPP) are designed to offer the best performances over open ocean surfaces (diffusive surface scattering mechanism). Notwithstanding, they may perform also very well in coastal zones unless: 1) the echoes suffer a really "heavy" contamination from the surrounding land 2) the echoes originate from very shallow and still coastal waters (specular surface scattering mechanism). This second case is not very frequent in coastal zones but it may be observed now more often because in SAR mode we have finally the possibility, in favourable conditions, to really reach the shoreline where a still water scenario can be encountered. Following the initial work presented at 6th Coastal Altimetry Workshop (2012), we will attempt to adapt the original open ocean SAMOSA SAR Echo Model to a coastal still water scenario. Indeed, the SAMOSA SAR Echo Model is a "water" model and can be used to reproduce a SAR Echo originated either from rough water surface (open ocean) either from standing water surface (bays, wetlands, lakes and rivers). The model adaptation to coastal still water scenario will be operated estimating the water surface rms slope (RMSSS) from the

  17. hPEPT1 affinity and translocation of selected Gln-Sar and Glu-Sar dipeptide derivatives.

    PubMed

    Eriksson, André Huss; Elm, Peter L; Begtrup, Mikael; Nielsen, Robert; Steffansen, Bente; Brodin, Birger

    2005-01-01

    The intestinal di- and tripeptide transporter hPEPT1 is considered responsible for the absorption of di- and tripeptides arising from digestion, along with several drugs and prodrugs. In order to gather information on the binding site of the protein, several structure-affinity relationships have been suggested. However, these are not necessarily predictive of compounds that are actually translocated by hPEPT1. More information on affinity to and translocation via hPEPT1 of side-chain-modified dipeptides may be gained by conducting a study of selected dipeptide derivatives with variety in size, hydrophobicity, and bond type. The aim of the present study was to synthesize new esters and amides based on L-Glu-Sar and investigate the effects that bond type and size of modification of the N-terminal side chain of sarcosine-containing dipeptides have on the affinity to and translocation via hPEPT1. The esters L-Glu(O-i-Bu)-Sar and L-Glu(OCH(2)Ada)-Sar and the amides L-Gln(N,N-dimethyl)-Sar and L-Gln(N-piperidinyl)-Sar were synthesized, and affinity to and translocation via hPEPT1 were investigated in mature Caco-2 cell monolayers, grown on permeable supports. Affinity was estimated in a competition assay using (14)C-labeled Gly-Sar. Translocation was measured as fluorescence ratios induced by the substrates using the fluorescent probe BCECF and an epifluorescence microscope setup. All compounds showed high affinity to hPEPT1, but only the amides L-Gln(N,N-dimethyl)-Sar and L-Gln(N-piperidinyl)-Sar were translocated by hPEPT1. hPEPT1 is very susceptible to modifications of the N-terminal amino acid side chain of dipeptidomimetic substrates, in terms of achieving compounds with high affinity for the transporter. However, as affinity is not predictive of translocation, derivatization in this position must be performed with great caution since some of the compounds investigated turn out not to be translocated by the transporter. PMID:15934785

  18. Developing an Error Model for Ionospheric Phase Distortions in L-Band SAR and InSAR Data

    NASA Astrophysics Data System (ADS)

    Meyer, F. J.; Agram, P. S.

    2014-12-01

    Many of the recent and upcoming spaceborne SAR systems are operating in the L-band frequency range. The choice of L-band has a number of advantages especially for InSAR applications. These include deeper penetration into vegetation, higher coherence, and higher sensitivity to soil moisture. While L-band SARs are undoubtedly beneficial for a number of earth science disciplines, their signals are susceptive to path delay effects in the ionosphere. Many recent publications indicate that the ionosphere can have detrimental effects on InSAR coherence and phase. It has also been shown that the magnitude of these effects strongly depends on the time of day and geographic location of the image acquisition as well as on the coincident solar activity. Hence, in order to provide realistic error estimates for geodetic measurements derived from L-band InSAR, an error model needs to be developed that is capable of describing ionospheric noise. With this paper, we present a global ionospheric error model that is currently being developed in support of NASA's future L-band SAR mission NISAR. The system is based on a combination of empirical data analysis and modeling input from the ionospheric model WBMOD, and is capable of predicting ionosphere-induced phase noise as a function of space and time. The error model parameterizes ionospheric noise using a power spectrum model and provides the parameters of this model in a global 1x1 degree raster. From the power law model, ionospheric errors in deformation estimates can be calculated. In Polar Regions, our error model relies on a statistical analysis of ionospheric-phase noise in a large number of SAR data from previous L-band SAR missions such as ALOS PALSAR and JERS-1. The focus on empirical analyses is due to limitations of WBMOD in high latitude areas. Outside of the Polar Regions, the ionospheric model WBMOD is used to derive ionospheric structure parameters for as a function of solar activity. The structure parameters are

  19. Sar and Maad TL Dating of Caroselli from three sites in Calabria, South Italy.

    NASA Astrophysics Data System (ADS)

    Gattuso, Caterina; Renzelli, Diana; Barone, Pasquale; Pingitore, Valentino; Oliva, Antonino

    In this work three types of "Caroselli" from different sites in Calabria have been studied. The "Carosello" is a structural hollow element made of clay, placed in arches, in domes or even in the walls of buildings such as churches and houses, with the function of relieving vaults and main structures. Diagnostic tests have been conducted on the "Caroselli" in order to determine the presence of luminescent material, the final goal being the age assessment of such artifacts using thermoluminescence (TL) techniques. Of course the historical frame of the buildings, to which "Caroselli" belong, is known from their style and architectural considerations. The scope of our dating is to supply additional information to clarify whether "Caroselli" were used from the very beginning of building construction or employed in subsequent restorations. The dating process has been conducted using two protocols, the Multiple Aliquot Additive Dose (MAAD) and the Single Aliquot Regenerative-dose (SAR), both by applying TL. The correction obtained by the SAR TL method is preferred because it allows a more accurate estimate of the equivalent dose and avoids problems arising from sample sensitivity. The results show that the three "Caroselli" can be respectively dated back to 1844±11, 1825±40, 1803±30 A.D.. Such results suggest that for two sites ("Madonna del Buonconsiglio" church and "Torre dello Zuino" colonial house), the "Caroselli", as structural elements, were used since the beginning of the building construction, while for the remaining site ("Pettoruto" church) probably the "Caroselli" were added in a successive restoration of the building, since the historical context of this building belongs to the fourteenth century.

  20. Automated extraction of pressure ridges from SAR images of sea ice - Comparison with surface truth

    NASA Technical Reports Server (NTRS)

    Vesecky, J. F.; Smith, M. P.; Samadani, R.; Daida, J. M.; Comiso, J. C.

    1991-01-01

    The authors estimate the characteristics of ridges and leads in sea ice from SAR (synthetic aperture radar) images. Such estimates are based on the hypothesis that bright filamentary features in SAR sea ice images correspond with pressure ridges. A data set collected in the Greenland Sea in 1987 allows this hypothesis to be evaluated for X-band SAR images. A preliminary analysis of data collected from SAR images and ice elevation (from a laser altimeter) is presented. It is found that SAR image brightness and ice elevation are clearly related. However, the correlation, using the data and techniques applied, is not strong.

  1. Rapid SAR target modeling through genetic inheritance mechanism

    NASA Astrophysics Data System (ADS)

    Bala, Jerzy; Pachowicz, Peter W.; Vafaie, Halleh

    1997-07-01

    The paper presents a methodology and GETP experimental system for rapid SAR target signature generation from limited initial sensory data. The methodology exploits and integrates the following four processes: (1) analysis of initial SAR image signatures and their transformation into higher-level blob representation, (2) blob modeling, (3) genetic inheritance modeling to generate new instances of a target model in blob representation, and (4) synthesis of new SAR signatures from genetically evolved blob data. The GETP system takes several SAR signatures of the target and transforms each signature into more general scattered blob graphs, where each blob represents local energy cluster. A single graph node is describe by blob relative position, confidence, and iconic data. Graph data is forwarded to the genetic modeling process while blob image is stored in a catalog. Genetic inheritance is applied to the initial population of graph data. New graph models of the target are generated and evaluated. Selected graph variations are forwarded to the synthesis process. The synthesis process restores target signature from a given graph and a catalog of blobs. The background is synthesized to complement the signature. Initial experimental results are illustrated with 64 X 32 image sections of a tank.

  2. Detecting and monitoring aquacultural patterns through multitemporal SAR imagery analysis

    NASA Astrophysics Data System (ADS)

    Profeti, Giuliana; Travaglia, Carlo; Carla, Roberto

    2003-03-01

    The inventory and monitoring of aquaculture areas are essential tools for decision-making at a governmental level in developing countries. With the use of satellite imagery, these tasks can be performed in an accurate, rapid and objective way. This approach is also economically viable, as the worth of aquaculture far outweighs its cost. This paper describes a methodology for identifying and monitoring shrimp farms by means of multi-temporal satellite SAR data. SAR offer all-weather capabilities, an important characteristic since shrimp farms exist in tropical and sub-tropical areas. Moreover, the backscatter effect created by the dykes surrounding the ponds produces a typical pattern which allows the interpreter to distinguish them from other types of water-covered surfaces. However, the presence of speckle noise limits the interpretability of SAR imagery. To increase it, a multi-temporal set of four scenes covering the study area was processed by using a method that enhances time-invariant spatial features and reduces speckle without compromising the geometrical resolution of the images. The enhanced SAR imagery has proved to be valuable in identifying shrimp farm patterns with a field-tested accuracy of more than 90 percent. The methodology reported in this study has been tested with the ground truth obtained under operative conditions in Sri Lanka, thanks to the support of the FAO TCP/SRL/6712 project.

  3. Onboard FPGA-based SAR processing for future spaceborne systems

    NASA Technical Reports Server (NTRS)

    Le, Charles; Chan, Samuel; Cheng, Frank; Fang, Winston; Fischman, Mark; Hensley, Scott; Johnson, Robert; Jourdan, Michael; Marina, Miguel; Parham, Bruce; Rogez, Francois; Rosen, Paul; Shah, Biren; Taft, Stephanie

    2004-01-01

    We present a real-time high-performance and fault-tolerant FPGA-based hardware architecture for the processing of synthetic aperture radar (SAR) images in future spaceborne system. In particular, we will discuss the integrated design approach, from top-level algorithm specifications and system requirements, design methodology, functional verification and performance validation, down to hardware design and implementation.

  4. A BRIEF DISCUSSION REGARDING PRION DISEASES AND SARS

    EPA Science Inventory

    Recent diagnoses of Mad Cow disease in Canadian and American cattle has increased concern for this disease and other TSEs in North America. This presentation provides a quick review of the important features of Mad Cow disease as well as SARS as they might relate to land applicat...

  5. Compact time- and space-integrating SAR processor: performance analysis

    NASA Astrophysics Data System (ADS)

    Haney, Michael W.; Levy, James J.; Michael, Robert R., Jr.; Christensen, Marc P.

    1995-06-01

    Progress made during the previous 12 months toward the fabrication and test of a flight demonstration prototype of the acousto-optic time- and space-integrating real-time SAR image formation processor is reported. Compact, rugged, and low-power analog optical signal processing techniques are used for the most computationally taxing portions of the SAR imaging problem to overcome the size and power consumption limitations of electronic approaches. Flexibility and performance are maintained by the use of digital electronics for the critical low-complexity filter generation and output image processing functions. The results reported for this year include tests of a laboratory version of the RAPID SAR concept on phase history data generated from real SAR high-resolution imagery; a description of the new compact 2D acousto-optic scanner that has a 2D space bandwidth product approaching 106 sports, specified and procured for NEOS Technologies during the last year; and a design and layout of the optical module portion of the flight-worthy prototype.

  6. SAR imaging via iterative adaptive approach and sparse Bayesian learning

    NASA Astrophysics Data System (ADS)

    Xue, Ming; Santiago, Enrique; Sedehi, Matteo; Tan, Xing; Li, Jian

    2009-05-01

    We consider sidelobe reduction and resolution enhancement in synthetic aperture radar (SAR) imaging via an iterative adaptive approach (IAA) and a sparse Bayesian learning (SBL) method. The nonparametric weighted least squares based IAA algorithm is a robust and user parameter-free adaptive approach originally proposed for array processing. We show that it can be used to form enhanced SAR images as well. SBL has been used as a sparse signal recovery algorithm for compressed sensing. It has been shown in the literature that SBL is easy to use and can recover sparse signals more accurately than the l 1 based optimization approaches, which require delicate choice of the user parameter. We consider using a modified expectation maximization (EM) based SBL algorithm, referred to as SBL-1, which is based on a three-stage hierarchical Bayesian model. SBL-1 is not only more accurate than benchmark SBL algorithms, but also converges faster. SBL-1 is used to further enhance the resolution of the SAR images formed by IAA. Both IAA and SBL-1 are shown to be effective, requiring only a limited number of iterations, and have no need for polar-to-Cartesian interpolation of the SAR collected data. This paper characterizes the achievable performance of these two approaches by processing the complex backscatter data from both a sparse case study and a backhoe vehicle in free space with different aperture sizes.

  7. Results of 1993 Repeat-Pass SAR Interferometry Experiments

    NASA Technical Reports Server (NTRS)

    Klein, J. D.; Hensley, S.; Madsen, S. N.; Webb, F. H.

    1994-01-01

    In this talk we present results of a repeat-pass SAR interferometry experiment performed in June 1993 near Portage, Maine. Differential GPS data accurate to +/-10cm were acquired to aid in motion compensation and geolocation of targets in the imagery. The experiment and data analysis will be discussed, and results will be shown during the presentation.

  8. Statistical and separability properties of the polarimetry SAR matrix elements

    NASA Astrophysics Data System (ADS)

    Bahrami, Ala; Sahebi, Mahmoud R.; Valadan Zouj, Mohammad J.; Ahmadi, Salman; Dehghani, Maryam; Nandipati, Anand

    2009-09-01

    The development of the polarimetric synthetic aperture radar (PolSAR) applications has been accelerated by coming of new generation of SAR polarimetric satellites (TerraSAR-X, COSMO-SkyMed, RADARSAT-2, ALOS, etc.). The aim of this article is to extract the information content of the polarimetric SAR data. Cross products of four channels "HH, HV, VH, and VV" could be at least nine features in vector space and by applying the different class separability criterion, the impacts of each feature, for extracting different patterns, could be tested. We have chosen the large distance between classes and small distance within-class variances as our criterion to rank the features. Due to high mutual correlation between some of the features, it is preferable to combine the features which result in the lower number of features. Also the computational complexity will be decreased when we have lower number of features. Due to these advantages, our goal would be to decrease the number of features in vector space. To achieve that, a subset of ranked features consists of two to nine ranked features will be classified and the classification accuracy of different subsets will be evaluated. It is possible that some of the new features that have been added to the old subsets change the classification accuracy. Finally different feature subsets which were selected based on the various class-separability approaches will be compared. The subset that gives the highest overall accuracy would be the best representative of the nine originally features.

  9. L band SAR ocean wave observations during Marsen

    NASA Astrophysics Data System (ADS)

    Jain, A.; Shemdin, O. H.

    1983-11-01

    The L Band Synthetic Aperture Radar (SAR) operated by the Jet Propulsion Laboratory (JPL) was flown over the Nordsee tower during the Marine Remote Sensing Experiment (MARSEN). The five-sided flight pattern allowed viewing of the same ocean surface patch from five different directions. The results form a unique and useful base which is needed for evaluating existing wave imaging theories and developing more realistic models. The results derived from analysis of radar and in situ measurements suggest that (1) the focus dependence for optimum imaging is that for a surface moving with a speed that is approximately equal to the wave phase velocity, (2) azimuthally traveling waves can be as visible as range traveling waves when the necessary focus adjustments are made in the SAR processor, (3) visibility of azimuthally traveling waves does not improve with decreasing integration time, (4) spectra and images of azimuthally traveling waves do not show observable distortions compared to those for range traveling waves, and (5) comparisons of SAR image spectra for September 28, 1979, with in situ wave height spectra suggest that for a multi-peaked wave system the SAR image spectrum and surface wave height spectrum are not connected by a simple relationship.

  10. Simultaneous SAR and GMTI using ATI/DPCA

    NASA Astrophysics Data System (ADS)

    Deming, Ross; Best, Matthew; Farrell, Sean

    2014-06-01

    In previous work, we presented GMTI detection and geo-location results from the AFRL Gotcha challenge data set, which was collected using a 3-channel, X-band, circular SAR system. These results were compared against GPS truth for a scripted vehicle target. The algorithm used for this analysis is known as ATI/DPCA, which is a hybrid of along-track interferometry (ATI) and the displaced phase center antenna (DPCA) technique. In the present paper the use of ATI/DPCA is extended in order to detect and geo-locate all observable moving targets in the Gotcha challenge data, including both the scripted movers and targets of opportunity. In addition, a computationally efficient SAR imaging technique is presented, appropriate for short integration times, which is used for computing an image of the scene of interest using the same pulses of data used for the GMTI processing. The GMTI detections are then overlaid on the SAR image to produce a simultaneous SAR/GMTI map.

  11. A Guide to 1998-99 SARs and ISIRs.

    ERIC Educational Resources Information Center

    Office of Postsecondary Education, Washington DC. Student Financial Assistance Programs.

    This guide for administrators of student financial aid programs at postsecondary education institutions is intended to assist in interpreting the codes that appear in the Student Aid Report (SAR), which is sent directly to the student, and in the Institutional Student Information Record (ISIR), which is an electronic report sent directly to…

  12. A Guide to 1999-2000 SARs and ISIRs.

    ERIC Educational Resources Information Center

    Office of Postsecondary Education, Washington DC. Student Financial Assistance Programs.

    This guide is intended to help financial aid administrators (FAAs) interpret student financial aid information that appears in the Student Aid Report (SAR), a paper output document sent to the student, or in an Institutional Student Information Record (ISIR), which is an electronic record sent to the institution. The guide explains the codes and…

  13. Suicidality Among High School Students in Hong Kong, SAR

    ERIC Educational Resources Information Center

    Yip, Paul S. F.; Liu, K. Y.; Lam, T. H.; Stewart, Sunita M.; Chen, Eric; Fan, Susan

    2004-01-01

    Suicide is the leading cause of death in Hong Kong SAR for the youth aged 15?24. This study examined the prevalence of suicidality among secondary school students in Hong Kong using a representative, territory-wide sample of 2,586 students. Suicidal behaviors can be conceptualized as a spectrum of self-destructive behaviors. Cumulative logit model…

  14. From Special to Inclusive Education in Macau (SAR)

    ERIC Educational Resources Information Center

    Forlin, Chris

    2011-01-01

    The education for learners with special education needs (SEN) in Macau (SAR), China, has gradually transitioned over the past 30 years from a completely segregated approach to a more inclusive one. Following a review of the development of special education and the transition towards inclusion in Macau, consideration is given to the enactment of…

  15. Remote sensing measurements of thermokarst subsidence using InSAR

    NASA Astrophysics Data System (ADS)

    Liu, L.; Schaefer, K. M.; Chen, A. C.; Gusmeroli, A.; Zebker, H. A.; Zhang, T.

    2015-09-01

    Thawing of ice-rich permafrost followed by surface subsidence results in irregular, depressed landforms known as thermokarst. Many remote sensing studies have identified thermokarst landforms and mapped their changes. However, the intrinsic dynamic thermokarst process of surface subsidence remains a challenge to quantify and is seldom examined using remote sensing methods. In this study we used spaceborne interferometric synthetic aperture radar (InSAR) data to map surface subsidence trends at a thermokarst landform located near Deadhorse on the North Slope of Alaska. A pipeline access road constructed in the 1970s triggered the thawing of the permafrost, causing subsequent expansion of the thermokarst landform. Using Phased Array type L band Synthetic Aperture Radar images acquired by the Advanced Land Observing Satellite-1, our InSAR analysis reveals localized thermokarst subsidence of 2-8 cm/yr between 2006 and 2010, equivalent to an ice volume loss of about 1.2 × 107 m3/yr. Comparisons between InSAR subsidence trends and lidar microtopography suggest a characteristic time of 8 years of thermokarst development. We also quantitatively explain the difficulty, uncertainties, and possible biases in separating thermokarst-induced, irreversible subsidence from cyclic seasonal deformation. Our study illustrates that InSAR is an effective tool for mapping and studying active thermokarst processes and quantifying ice loss.

  16. An automated system for mosaicking spaceborne SAR imagery

    NASA Technical Reports Server (NTRS)

    Kwok, Ronald; Curlander, John C.; Pang, Shirley S.

    1990-01-01

    An automated system has been developed for mosaicking spaceborne synthetic aperture radar (SAR) imagery. The system is capable of producing multiframe mosaics for large-scale mapping by combining images in both the along-track direction and adjacent cross-track swaths from ascending and descending passes. The system requires no operator interaction and is capable of achieving high registration accuracy. The output product is a geocoded mosaic on a standard map grid such as UTM or polar stereographic. The procedure described in detail in this paper consists essentially of remapping the individual image frames into these standard grids, frame-to-frame image registration and radiometric smoothing of the seams. These procedures are directly applicable to both the Magellan Venus Mapper and a scanning SAR design such as Radarsat, Eos SAR in addition to merging image frames from traditional SAR systems such as SEASAT and SIR-B. With minor modifications, it may also be applied to spaceborne optical sensor data to generate large-scale mosaics efficiently and with a high degree of accuracy. The system has been tested with SEASAT, SIR-B and Landsat TM data. Examples presented in this paper include a 38-frame mosaic of the Yukon River basin in central Alaska, a 33-frame mosaic of southern California and a three-frame terrain-corrected geocoded mosaic of the Wind River basin in Wyoming.

  17. The Performance Analysis Based on SAR Sample Covariance Matrix

    PubMed Central

    Erten, Esra

    2012-01-01

    Multi-channel systems appear in several fields of application in science. In the Synthetic Aperture Radar (SAR) context, multi-channel systems may refer to different domains, as multi-polarization, multi-interferometric or multi-temporal data, or even a combination of them. Due to the inherent speckle phenomenon present in SAR images, the statistical description of the data is almost mandatory for its utilization. The complex images acquired over natural media present in general zero-mean circular Gaussian characteristics. In this case, second order statistics as the multi-channel covariance matrix fully describe the data. For practical situations however, the covariance matrix has to be estimated using a limited number of samples, and this sample covariance matrix follow the complex Wishart distribution. In this context, the eigendecomposition of the multi-channel covariance matrix has been shown in different areas of high relevance regarding the physical properties of the imaged scene. Specifically, the maximum eigenvalue of the covariance matrix has been frequently used in different applications as target or change detection, estimation of the dominant scattering mechanism in polarimetric data, moving target indication, etc. In this paper, the statistical behavior of the maximum eigenvalue derived from the eigendecomposition of the sample multi-channel covariance matrix in terms of multi-channel SAR images is simplified for SAR community. Validation is performed against simulated data and examples of estimation and detection problems using the analytical expressions are as well given. PMID:22736976

  18. Deriving sea-state parameters using RISAT-1 SAR data

    NASA Astrophysics Data System (ADS)

    Ganguly, Debojyoti; Mishra, Manoj K.; Chauhan, Prakash

    2015-01-01

    A technique has been demonstrated for deriving various sea-wave parameters such as peak wavelength, peak direction, and significant wave height from two-dimensional synthetic aperture radar (SAR) data acquired by Indian active microwave remote-sensing satellite RISAT-1 (Radar Imaging Satellite 1). The significant wave height is obtained using the method of azimuth cutoff wavelength, which is the minimum wavelength that can be imaged in the azimuth direction and results due to the roll-off of the SAR image spectra at higher wave numbers. In the present paper, RISAT-1 SAR fine-resolution scan mode intensity image data are used for deriving various wave parameters at a high spatial resolution of 300 m. The changes in wavelength, wave height, and wave direction of sea waves are studied for a coastal wave system using high-resolution sea-wave spectral information. The SAR-derived coastal wave parameters are then compared with JASON-2 altimeter Geophysical Data Record (GDR) products and The European Center for Medium-Range Weather Forecasts (ECMWF)-modeled values, and are found to be in reasonable agreement.

  19. A fully automated TerraSAR-X based flood service

    NASA Astrophysics Data System (ADS)

    Martinis, Sandro; Kersten, Jens; Twele, André

    2015-06-01

    In this paper, a fully automated processing chain for near real-time flood detection using high resolution TerraSAR-X Synthetic Aperture Radar (SAR) data is presented. The processing chain including SAR data pre-processing, computation and adaption of global auxiliary data, unsupervised initialization of the classification as well as post-classification refinement by using a fuzzy logic-based approach is automatically triggered after satellite data delivery. The dissemination of flood maps resulting from this service is performed through an online service which can be activated on-demand for emergency response purposes (i.e., when a flood situation evolves). The classification methodology is based on previous work of the authors but was substantially refined and extended for robustness and transferability to guarantee high classification accuracy under different environmental conditions and sensor configurations. With respect to accuracy and computational effort, experiments performed on a data set of 175 different TerraSAR-X scenes acquired during flooding all over the world with different sensor configurations confirm the robustness and effectiveness of the proposed flood mapping service. These promising results have been further confirmed by means of an in-depth validation performed for three study sites in Germany, Thailand, and Albania/Montenegro.

  20. A Guide to 2000-2001 SARs and ISIRs.

    ERIC Educational Resources Information Center

    Office of Student Financial Assistance (ED), Washington, DC.

    This guide is intended to assist financial aid officers interpret the coding on the Student Aid Report (SAR), which is sent directly to students, and on the Institutional Student Information Record (ISIR), which is sent directly to institutions, in order to help students make the necessary corrections to their financial aid application data. The…

  1. SAR/QSAR methods in public health practice

    SciTech Connect

    Demchuk, Eugene Ruiz, Patricia; Chou, Selene; Fowler, Bruce A.

    2011-07-15

    Methods of (Quantitative) Structure-Activity Relationship ((Q)SAR) modeling play an important and active role in ATSDR programs in support of the Agency mission to protect human populations from exposure to environmental contaminants. They are used for cross-chemical extrapolation to complement the traditional toxicological approach when chemical-specific information is unavailable. SAR and QSAR methods are used to investigate adverse health effects and exposure levels, bioavailability, and pharmacokinetic properties of hazardous chemical compounds. They are applied as a part of an integrated systematic approach in the development of Health Guidance Values (HGVs), such as ATSDR Minimal Risk Levels, which are used to protect populations exposed to toxic chemicals at hazardous waste sites. (Q)SAR analyses are incorporated into ATSDR documents (such as the toxicological profiles and chemical-specific health consultations) to support environmental health assessments, prioritization of environmental chemical hazards, and to improve study design, when filling the priority data needs (PDNs) as mandated by Congress, in instances when experimental information is insufficient. These cases are illustrated by several examples, which explain how ATSDR applies (Q)SAR methods in public health practice.

  2. GMTI for Squint Looking XTI-SAR with Rotatable Forward-Looking Array

    PubMed Central

    Jing, Kai; Xu, Jia; Huang, Zuzhen; Yao, Di; Long, Teng

    2016-01-01

    To realize ground moving target indication (GMTI) for a forward-looking array, we propose a novel synthetic aperture radar (SAR) system, called rotatable cross-track interferometry SAR (Ro-XTI-SAR), for squint-looking application in this paper. By changing the angle of the cross-track baseline, the interferometry phase component of squint-looking Ro-XTI-SAR caused by the terrain height can be approximately adjusted to zero, and then the interferometry phase of Ro-XTI-SAR is only sensitive to targets’ motion and can be equivalent to the along track interferometry SAR (ATI-SAR). Furthermore, the conventional displaced phase center array (DPCA) method and constant false alarm (CFAR) processing can be used to accomplish the successive clutter suppression, moving targets detection and relocation. Furthermore, the clutter suppressing performance is discussed with respect to different system parameters. Finally, some results of numerical experiments are provided to demonstrate the effectiveness of the proposed system. PMID:27314350

  3. GMTI for Squint Looking XTI-SAR with Rotatable Forward-Looking Array.

    PubMed

    Jing, Kai; Xu, Jia; Huang, Zuzhen; Yao, Di; Long, Teng

    2016-01-01

    To realize ground moving target indication (GMTI) for a forward-looking array, we propose a novel synthetic aperture radar (SAR) system, called rotatable cross-track interferometry SAR (Ro-XTI-SAR), for squint-looking application in this paper. By changing the angle of the cross-track baseline, the interferometry phase component of squint-looking Ro-XTI-SAR caused by the terrain height can be approximately adjusted to zero, and then the interferometry phase of Ro-XTI-SAR is only sensitive to targets' motion and can be equivalent to the along track interferometry SAR (ATI-SAR). Furthermore, the conventional displaced phase center array (DPCA) method and constant false alarm (CFAR) processing can be used to accomplish the successive clutter suppression, moving targets detection and relocation. Furthermore, the clutter suppressing performance is discussed with respect to different system parameters. Finally, some results of numerical experiments are provided to demonstrate the effectiveness of the proposed system. PMID:27314350

  4. Mechanisms for SAR imaging of ocean surface phenomena: Theory and experiment

    NASA Technical Reports Server (NTRS)

    Vesecky, J. F.

    1983-01-01

    Understanding the SAR response to surface wave is a central issue in the analysis of SAR ocean images. The imaging mechanism for gravity waves and the practical question of just which characteristics of the ocean wave field can be measured remotely using SAR were examined. Assessments of wave imaging theory are based primarily on comparisons of the directional wave height variance spectrum psi (K) measured by in situ buoys with estimates from SAR images. Other criteria are also recommended, e.g., the effects of focus adjustments. It is assumed that fluctuations in SAR image intensity are proportional to fluctuations in ocean surface height. If this were true, the Fourier power spectrum of a SAR image and corresponding surface measurements of psi would coincide. Differences between SAR estimates based on this hypothesis and buoy measurements of psi are then used to begin the assessment of rival wave imaging theories.

  5. Recent Advances in Radar Polarimetry and Polarimetric SAR Interferometry

    NASA Technical Reports Server (NTRS)

    Boerner, Wolfgang-Martin

    2005-01-01

    The development of Radar Polarimetry and Radar Interferometry is advancing rapidly, and these novel radar technologies are revamping Synthetic Aperture Radar Imaging decisively. In this exposition the successive advancements are sketched; beginning with the fundamental formulations and high-lighting the salient points of these diverse remote sensing techniques. Whereas with radar polarimetry the textural fine-structure, target-orientation and shape, symmetries and material constituents can be recovered with considerable improvements above that of standard amplitude-only Polarization Radar ; with radar interferometry the spatial (in depth) structure can be explored. In Polarimetric-Interferometric Synthetic Aperture Radar (POL-IN-SAR) Imaging it is possible to recover such co-registered textural plus spatial properties simultaneously. This includes the extraction of Digital Elevation Maps (DEM) from either fully Polarimetric (scattering matrix) or Interferometric (dual antenna) SAR image data takes with the additional benefit of obtaining co-registered three-dimensional POL-IN-DEM information. Extra-Wide-Band POL-IN-SAR Imaging - when applied to Repeat-Pass Image Overlay Interferometry - provides differential background validation and measurement, stress assessment, and environmental stress-change monitoring capabilities with hitherto unattained accuracy, which are essential tools for improved global biomass estimation. More recently, by applying multiple parallel repeat-pass EWB-POL-D(RP)-IN-SAR imaging along stacked (altitudinal) or displaced (horizontal) flight-lines will result in Tomographic (Multi- Interferometric) Polarimetric SAR Stereo-Imaging , including foliage and ground penetrating capabilities. It is shown that the accelerated advancement of these modern EWB-POL-D(RP)-IN-SAR imaging techniques is of direct relevance and of paramount priority to wide-area dynamic homeland security surveillance and local-to-global environmental ground-truth measurement

  6. Space Radar Image of West Texas - SAR scan

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This radar image of the Midland/Odessa region of West Texas, demonstrates an experimental technique, called ScanSAR, that allows scientists to rapidly image large areas of the Earth's surface. The large image covers an area 245 kilometers by 225 kilometers (152 miles by 139 miles). It was obtained by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) flying aboard the space shuttle Endeavour on October 5, 1994. The smaller inset image is a standard SIR-C image showing a portion of the same area, 100 kilometers by 57 kilometers (62 miles by 35 miles) and was taken during the first flight of SIR-C on April 14, 1994. The bright spots on the right side of the image are the cities of Odessa (left) and Midland (right), Texas. The Pecos River runs from the top center to the bottom center of the image. Along the left side of the image are, from top to bottom, parts of the Guadalupe, Davis and Santiago Mountains. North is toward the upper right. Unlike conventional radar imaging, in which a radar continuously illuminates a single ground swath as the space shuttle passes over the terrain, a Scansar radar illuminates several adjacent ground swaths almost simultaneously, by 'scanning' the radar beam across a large area in a rapid sequence. The adjacent swaths, typically about 50 km (31 miles) wide, are then merged during ground processing to produce a single large scene. Illumination for this L-band scene is from the top of the image. The beams were scanned from the top of the scene to the bottom, as the shuttle flew from left to right. This scene was acquired in about 30 seconds. A normal SIR-C image is acquired in about 13 seconds. The ScanSAR mode will likely be used on future radar sensors to construct regional and possibly global radar images and topographic maps. The ScanSAR processor is being designed for 1996 implementation at NASA's Alaska SAR Facility, located at the University of Alaska Fairbanks, and will produce digital images from the

  7. Agricultural Land Cover from Multitemporal C-Band SAR Data

    NASA Astrophysics Data System (ADS)

    Skriver, H.

    2013-12-01

    Henning Skriver DTU Space, Technical University of Denmark Ørsteds Plads, Building 348, DK-2800 Lyngby e-mail: hs@space.dtu.dk Problem description This paper focuses on land cover type from SAR data using high revisit acquisitions, including single and dual polarisation and fully polarimetric data, at C-band. The data set were acquired during an ESA-supported campaign, AgriSAR09, with the Radarsat-2 system. Ground surveys to obtain detailed land cover maps were performed during the campaign. Classification methods using single- and dual-polarisation data, and fully polarimetric data are used with multitemporal data with short revisit time. Results for airborne campaigns have previously been reported in Skriver et al. (2011) and Skriver (2012). In this paper, the short revisit satellite SAR data will be used to assess the trade-off between polarimetric SAR data and data as single or dual polarisation SAR data. This is particularly important in relation to the future GMES Sentinel-1 SAR satellites, where two satellites with a relatively wide swath will ensure a short revisit time globally. Questions dealt with are: which accuracy can we expect from a mission like the Sentinel-1, what is the improvement of using polarimetric SAR compared to single or dual polarisation SAR, and what is the optimum number of acquisitions needed. Methodology The data have sufficient number of looks for the Gaussian assumption to be valid for the backscatter coefficients for the individual polarizations. The classification method used for these data is therefore the standard Bayesian classification method for multivariate Gaussian statistics. For the full-polarimetric cases two classification methods have been applied, the standard ML Wishart classifier, and a method based on a reversible transform of the covariance matrix into backscatter intensities. The following pre-processing steps were performed on both data sets: The scattering matrix data in the form of SLC products were

  8. Internal Wave Study in the South China Sea Using SAR

    NASA Technical Reports Server (NTRS)

    Liu, Antony K.; Hsu, Ming-Kuang; Zukor, Dorothy (Technical Monitor)

    2000-01-01

    Recently, the internal wave distribution maps in the China Seas have been compiled from hundreds of ERS-1/2, RADARSAT, and Space Shuttle SAR (Synthetic Aperture Radar) images from 1993 to 1999. Based on internal wave distribution map, most of internal waves in the northeast part of South China Sea were propagating westward. The wave crest can be as long as 200 km with amplitude of 100 m due to strong current from the Kuroshio branching out into the South China Sea. Based on the observations from drilling rigs near DongSha Island by Amoco Production Co., the solitons may be generated in a 4 km wide channel between Batan and Sabtang islands in Luzon Strait. The proposed generation mechanism is similar to the lee wave formation from a shallow topography. Both depression and elevation internal waves have been observed in the same RADARSAT ScanSAR image on May 4, 1998 near DongSha Island. Furthermore, depression and elevation internal waves have also been observed by SAR at the same location on the shelf in April and June, 1993 (in different seasons) respectively. Numerical models have been used to interpret their generation mechanism and evolution processes. Based on the SAR images, near DongSha Island, the westward propagating huge internal solitons are often encountered and diffracted/broken by the coral reefs on the shelf. After passing the island, the diffracted waves will re-merge or interact with each other. It has been observed that after the nonlinear wave-wave interaction, the phase of wave packet is shifted and wavelength is also changed. Examples of mesoscale features observed in SAR images, such as fronts, raincells, bathymetry, ship wakes, and oil spills will be presented. Recent mooring measurements in April 1999 near Dongsha Island, future field test ASIAEX (Asian Seas International Acoustics Experiment) planned for April 2001, and some pretest survey data will be discussed in this paper.

  9. Utilizing SAR and Multispectral Integrated Data for Emergency Response

    NASA Astrophysics Data System (ADS)

    Havivi, S.; Schvartzman, I.; Maman, S.; Marinoni, A.; Gamba, P.; Rotman, S. R.; Blumberg, D. G.

    2016-06-01

    Satellite images are used widely in the risk cycle to understand the exposure, refine hazard maps and quickly provide an assessment after a natural or man-made disaster. Though there are different types of satellite images (e.g. optical, radar) these have not been combined for risk assessments. The characteristics of different remote sensing data type may be extremely valuable for monitoring and evaluating the impacts of disaster events, to extract additional information thus making it available for emergency situations. To base this approach, two different change detection methods, for two different sensor's data were used: Coherence Change Detection (CCD) for SAR data and Covariance Equalization (CE) for multispectral imagery. The CCD provides an identification of the stability of an area, and shows where changes have occurred. CCD shows subtle changes with an accuracy of several millimetres to centimetres. The CE method overcomes the atmospheric effects differences between two multispectral images, taken at different times. Therefore, areas that had undergone a major change can be detected. To achieve our goals, we focused on the urban areas affected by the tsunami event in Sendai, Japan that occurred on March 11, 2011 which affected the surrounding area, coastline and inland. High resolution TerraSAR-X (TSX) and Landsat 7 images, covering the research area, were acquired for the period before and after the event. All pre-processed and processed according to each sensor. Both results, of the optical and SAR algorithms, were combined by resampling the spatial resolution of the Multispectral data to the SAR resolution. This was applied by spatial linear interpolation. A score representing the damage level in both products was assigned. The results of both algorithms, high level of damage is shown in the areas closer to the sea and shoreline. Our approach, combining SAR and multispectral images, leads to more reliable information and provides a complete scene for

  10. InSAR-Detected Tidal Flow in Louisiana's Coastal Wetlands

    NASA Astrophysics Data System (ADS)

    Oliver-Cabrera, T.; Wdowinski, S.

    2014-12-01

    The Louisiana coast is among the most productive coastal area in the US and home to the largest coastal wetland area in the nation. However, Louisiana coastal wetlands have been threatened by natural (sea-level rise) and human (infrastructure development) stresses; they constitute the major part of the wetland loss of the country. Monitoring Louisiana's coastal wetlands represent a large challenge for local and federal authorities due to the large amount of area and hostile environment. Insofar, optical remote sensing observations have been used to classify the wetlands, monitor land cover changes, and assess the wetland loss over time. However, optical data is insensitive to surface flow and, hence, unable to detect the width of the tidal zone and changes in this area over time. SAR interferometry can provide useful information and ease the monitoring task. Wetland InSAR is the only application of the InSAR technology that provides information of aquatic surface. It provides useful information on surface water level changes in both inland and coastal wetlands. In this study, we use InSAR and tide gauge observations to detect and compare surface water level changes in response to ocean tide propagation through the Louisiana coastal wetlands. Our data consist of ALOS PALSAR, Radarsat-1 and tide gauge information over the coast of Louisiana. In order to detect water level changes, we used mainly high coherence interferferograms with short temporal baselines (46-92 days for ALOS data and 24-48 days for Radarsat-1). Interferometric processing of the data provides details maps of water level changes in the coastal zone. Preliminary results indicate tidal changes of up 30 cm and that tidal flow is limited to 8-10 km from the open water. Our results also show that the tidal flow is disrupted by various man-made structures as, canals and roads. The high spatial resolution wetland InSAR observations can provide useful constraints for detailed coastal wetland flow models.

  11. Global Tropospheric Noise Maps for InSAR Observations

    NASA Astrophysics Data System (ADS)

    Yun, S. H.; Hensley, S.; Agram, P. S.; Chaubell, M.; Fielding, E. J.; Pan, L.

    2014-12-01

    Radio wave's differential phase delay variation through the troposphere is the largest error sources in Interferometric Synthetic Aperture Radar (InSAR) measurements, and water vapor variability in the troposphere is known to be the dominant factor. We use the precipitable water vapor (PWV) products from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) sensors mounted on Terra and Aqua satellites to produce tropospheric noise maps of InSAR. We estimate the slope and y-intercept of power spectral density curve of MODIS PWV and calculate the structure function to estimate the expected tropospheric noise level as a function of distance. The results serve two purposes: 1) to provide guidance on the expected covariance matrix for geophysical modeling, 2) to provide quantitative basis for the science Level-1 requirements of the planned NASA-ISRO L-band SAR mission (NISAR mission). We populate lookup tables of such power spectrum parameters derived from each 1-by-1 degree tile of global coverage. The MODIS data were retrieved from OSCAR (Online Services for Correcting Atmosphere in Radar) server. Users will be able to use the lookup tables and calculate expected tropospheric noise level of any date of MODIS data at any distance scale. Such calculation results can be used for constructing covariance matrix for geophysical modeling, or building statistics to support InSAR missions' requirements. For example, about 74% of the world had InSAR tropospheric noise level (along a radar line-of-sight for an incidence angle of 40 degrees) of 2 cm or less at 50 km distance scale during the time period of 2010/01/01 - 2010/01/09.

  12. A TDMA MIMO SAR radar for automated position-keeping

    NASA Astrophysics Data System (ADS)

    Wang, Zhonghai; Lin, Xingping; Cumber, Steven; Fish, Ensign John; Pham, Khanh; Blasch, Erik; Chen, Genshe; Shen, Dan; Jia, Bin; Wang, Gang

    2015-05-01

    This paper presents a time division multiple access (TDMA) multiple-input and multiple-output (MIMO) synthetic aperture radar (SAR) with a sliding range window for automated position-keeping, which can be applied in vessel tracking/escorting, offshore deepwater drillship equipment servicing, etc. A MIMO SAR sensor predefines a special part of the target (i.e., the drillship, ship, or submarine) as the measurement target and does not need special assistant devices/targets installed on the target vessel/platform, so its application is convenient. In the measurement process, the sensor scans the target with multiple ranging gates, forms images of multiple sections of the target, detects the predefined part/target in these images, and then obtains the range and angle of the predefined target for relative localization. Our MIMO SAR has 13 transmitting antennas and 8 receiving antennas. All transmitting antennas share a transmitter and all receiving antennas share a receiver using switches to reduce cost. The MIMO SAR radar has 44 effective SAR phase centers, and the azimuth angle resolution is θ0.5/44 (finest, θ 0.5 is the antenna element's 3dB beamwidth). The transmitter transmits a chirped linear frequency modulated continuous wave (LFMCW) signal, and the receiver only processes the signal limited in the beat frequency region defined by the distance from the measurement target to the sensor and the interested measurement target extension, which is determined by the receiver bandwidth. With the sliding range window, the sensor covers a large range, and in the covered range window, it provides high accuracy measurements.

  13. From SARS coronavirus to novel animal and human coronaviruses

    PubMed Central

    To, Kelvin K. W.; Hung, Ivan F. N.; Chan, Jasper F. W.

    2013-01-01

    In 2003, severe acute respiratory syndrome coronavirus (SARS-CoV) caused one of the most devastating epidemics known to the developed world. There were two important lessons from this epidemic. Firstly, coronaviruses, in addition to influenza viruses, can cause severe and rapidly spreading human infections. Secondly, bats can serve as the origin and natural animal reservoir of deadly human viruses. Since then, researchers around the world, especially those in Asia where SARS-CoV was first identified, have turned their focus to find novel coronaviruses infecting humans, bats, and other animals. Two human coronaviruses, HCoV-HKU1 and HCoV-NL63, were identified shortly after the SARS-CoV epidemic as common causes of human respiratory tract infections. In 2012, a novel human coronavirus, now called Middle East respiratory syndrome coronavirus (MERS-CoV), has emerged in the Middle East to cause fatal human infections in three continents. MERS-CoV human infection is similar to SARS-CoV in having a high fatality rate and the ability to spread from person to person which resulted in secondary cases among close contacts including healthcare workers without travel history to the Middle East. Both viruses also have close relationships with bat coronaviruses. New cases of MERS-CoV infection in humans continue to occur with the origins of the virus still unknown in many cases. A multifaceted approach is necessary to control this evolving MERS-CoV outbreak. Source identification requires detailed epidemiological studies of the infected patients and enhanced surveillance of MERS-CoV or similar coronaviruses in humans and animals. Early diagnosis of infected patients and appropriate infection control measures will limit the spread in hospitals, while social distancing strategies may be necessary to control the outbreak in communities if it remained uncontrolled as in the SARS epidemic. PMID:23977429

  14. Software for Generating Strip Maps from SAR Data

    NASA Technical Reports Server (NTRS)

    Hensley, Scott; Michel, Thierry; Madsen, Soren; Chapin, Elaine; Rodriguez, Ernesto

    2004-01-01

    Jurassicprok is a computer program that generates strip-map digital elevation models and other data products from raw data acquired by an airborne synthetic-aperture radar (SAR) system. This software can process data from a variety of airborne SAR systems but is designed especially for the GeoSAR system, which is a dual-frequency (P- and X-band), single-pass interferometric SAR system for measuring elevation both at the bare ground surface and top of the vegetation canopy. Jurassicprok is a modified version of software developed previously for airborne-interferometric- SAR applications. The modifications were made to accommodate P-band interferometric processing, remove approximations that are not generally valid, and reduce processor-induced mapping errors to the centimeter level. Major additions and other improvements over the prior software include the following: a) A new, highly efficient multi-stage-modified wave-domain processing algorithm for accurately motion compensating ultra-wideband data; b) Adaptive regridding algorithms based on estimated noise and actual measured topography to reduce noise while maintaining spatial resolution; c) Exact expressions for height determination from interferogram data; d) Fully calibrated volumetric correlation data based on rigorous removal of geometric and signal-to-noise decorrelation terms; e) Strip range-Doppler image output in user-specified Doppler coordinates; f) An improved phase-unwrapping and absolute-phase-determination algorithm; g) A more flexible user interface with many additional processing options; h) Increased interferogram filtering options; and i) Ability to use disk space instead of random- access memory for some processing steps.

  15. SAR image construction from periodically gapped phase-history data

    NASA Astrophysics Data System (ADS)

    Larsson, Erik G.; Li, Jianwei J.

    2002-08-01

    It is known that high-resolution synthetic aperture radar (SAR) imaging can be cast as a spectral analysis problem, and consequently a number of sophisticated spectral estimation methods have been applied to SAR imaging. These method include the classical Capon method and the closely related Amplitude and Phase Estimation (APES) algorithm. In this paper, we show how Capon and APES can be extended to deal with spectral analysis of periodically gapped (PG) data, i.e. data where samples are missing in a periodic fashion. This problem is highly relevant for SAR imaging with angular diversity since in that case the measured phase-history data matrix contains missing columns. Our extension of Capon and APES is based on a transform that maps a one-dimensional (1D) periodically gapped time-series into a uniformly sampled two-dimensional (2D) data set. We show that the stationarity properties of the 1D signal are left unchanged by the transformation, and as a result the conventional 2D Capon and APES methods can be applied to the transformed data. An associated inverse transform is used to extract the 1D spectral estimate from the 2D one. The new method is computationally and conceptually non-intricate and it does not involve any interpolation of the missing data. Despite its striking simplicity, numerical results indicate that the new method can be a promising tool for SAR imaging with angular diversity as well as for time-series analysis. In SAR applications, the new method may be particularly suitable for accurate imaging of a small region of interest.

  16. Evaluation of the operational SAR based Baltic sea ice concentration products

    NASA Astrophysics Data System (ADS)

    Karvonen, Juha

    Sea ice concentration is an important ice parameter both for weather and climate modeling and sea ice navigation. We have developed an fully automated algorithm for sea ice concentration retrieval using dual-polarized ScanSAR wide mode RADARSAT-2 data. RADARSAT-2 is a C-band SAR instrument enabling dual-polarized acquisition in ScanSAR mode. The swath width for the RADARSAT-2 ScanSAR mode is about 500 km, making it very suitable for operational sea ice monitoring. The polarization combination used in our concentration estimation is HH/HV. The SAR data is first preprocessed, the preprocessing consists of geo-rectification to Mercator projection, incidence angle correction fro both the polarization channels. and SAR mosaicking. After preprocessing a segmentation is performed for the SAR mosaics, and some single-channel and dual-channel features are computed for each SAR segment. Finally the SAR concentration is estimated based on these segment-wise features. The algorithm is similar as introduced in Karvonen 2014. The ice concentration is computed daily using a daily RADARSAT-2 SAR mosaic as its input, and it thus gives the concentration estimated at each Baltic Sea location based on the most recent SAR data at the location. The algorithm has been run in an operational test mode since January 2014. We present evaluation of the SAR-based concentration estimates for the Baltic ice season 2014 by comparing the SAR results with gridded the Finnish Ice Service ice charts and ice concentration estimates from a radiometer algorithm (AMSR-2 Bootstrap algorithm results). References: J. Karvonen, Baltic Sea Ice Concentration Estimation Based on C-Band Dual-Polarized SAR Data, IEEE Transactions on Geoscience and Remote Sensing, in press, DOI: 10.1109/TGRS.2013.2290331, 2014.

  17. InSAR Terrain Mapping Using ICESat Laser Altimetry

    NASA Astrophysics Data System (ADS)

    Atwood, D.; Guritz, R.; Muskett, R.; Lingle, C.; Sauber, J.

    2006-12-01

    High quality geodetic ground control is time-consuming and costly to acquire in remote regions, where logistical operations are difficult to support. Hence, there is a strong interest in establishing new sources of ground control points that can be used in conjunction with Interferometric SAR (InSAR) for producing accurate digital elevation models (DEMs). In January 2003, NASA launched the Geoscience Laser Altimeter System (GLAS) into high polar orbit onboard the Ice, Cloud, and land Elevation Satellite (ICESat). A major objective of this spaceborne laser altimeter system, with orbital coverage extending from 86° N to 86° S, is to provide elevation measurements of the Earth's topography with unprecedented accuracy. The intent of our project is to assess the accuracy of ICESat elevation data and evaluate its utility as ground control for topographic mapping. Our study area lies near Barrow, Alaska; 15,650 sq. km of coastal plain adjacent to the Arctic Ocean, characterized by vast expanses of tundra, lakes, and arctic wetlands of such low relief as to be nearly devoid of terrain features. Accuracy of the ICESat elevation measurements is assessed through comparison with differential GPS (DGPS) data, acquired along ICESat ground tracks crossing our study area. Using DGPS as the reference, ICESat yields a mean offset of -0.04 ± 0.15 m for fast static measurements on frozen tundra lakes and 0.22 ± 0.96 m for two kinematic DGPS profiles along the ICESat ground track. These results suggests that ICESat-derived elevations on the Arctic coastal plain are more than sufficiently accurate for use as ground control in DEM generation. The only clear limitation of the ICESat data is the non-uniform distribution of the ICESat tracks within the 33 day near-repeat sub-cycle. Although the coverage is poor at equatorial latitudes, track separation in the Arctic is on the order of tens of kilometers because of orbital convergence at the Poles. To test whether these data can be used

  18. Modified Multilook Cross Correlation technique for Doppler centroid estimation in SAR image signal processing

    NASA Astrophysics Data System (ADS)

    Bee Cheng, Sew

    Synthetic Aperture Radar (SAR) is one of the widely used remote sensing sensors which produces high resolution image by using advance signal processing technique. SAR managed to operate in all sorts of weather and cover wide range of area. To produce a high-quality image, accurate parameters such as Doppler centroid are required for precise SAR signal processing. In the azimuth matched filtering of SAR signal processing, Doppler centroid is an important azimuth parameter that helps to focus the image pixels. Doppler centroid has always been overlooked during SAR signal processing. It is due to the fact that estimation of Doppler centroid involved complicated calculation and increased computational load. Therefore, researcher used to apply only the approximate Doppler value which is not precise and cause defocus effort in the generated SAR image. In this study, several conventional Doppler centroid estimation algorithms are reviewed and developed using Matlab software program to extract the Doppler parameter from received SAR data, namely Spectrum Fit Algorithm, Wavelength Diversity Algorithm (WDA), Multilook Cross Correlation Algorithm (MLCC), and Multilook Beat Frequency Algorithm (MLBF). Two sets of SAR data are employed to evaluate the performance of each estimator, i.e. simulated point target data and RADARSAT-1 Vancouver scene raw data. These experiments gave a sense of accuracy for the estimated results together with computational time consumption. Point target is simulated to generate ideal case SAR data with pre-defined SAR system parameters.

  19. An RF dosimeter for independent SAR measurement in MRI scanners

    PubMed Central

    Qian, Di; El-Sharkawy, AbdEl-Monem M.; Bottomley, Paul A.; Edelstein, William A.

    2013-01-01

    Purpose: The monitoring and management of radio frequency (RF) exposure is critical for ensuring magnetic resonance imaging (MRI) safety. Commercial MRI scanners can overestimate specific absorption rates (SAR) and improperly restrict clinical MRI scans or the application of new MRI sequences, while underestimation of SAR can lead to tissue heating and thermal injury. Accurate scanner-independent RF dosimetry is essential for measuring actual exposure when SAR is critical for ensuring regulatory compliance and MRI safety, for establishing RF exposure while evaluating interventional leads and devices, and for routine MRI quality assessment by medical physicists. However, at present there are no scanner-independent SAR dosimeters. Methods: An SAR dosimeter with an RF transducer comprises two orthogonal, rectangular copper loops and a spherical MRI phantom. The transducer is placed in the magnet bore and calibrated to approximate the resistive loading of the scanner's whole-body birdcage RF coil for human subjects in Philips, GE and Siemens 3 tesla (3T) MRI scanners. The transducer loop reactances are adjusted to minimize interference with the transmit RF field (B1) at the MRI frequency. Power from the RF transducer is sampled with a high dynamic range power monitor and recorded on a computer. The deposited power is calibrated and tested on eight different MRI scanners. Whole-body absorbed power vs weight and body mass index (BMI) is measured directly on 26 subjects. Results: A single linear calibration curve sufficed for RF dosimetry at 127.8 MHz on three different Philips and three GE 3T MRI scanners. An RF dosimeter operating at 123.2 MHz on two Siemens 3T scanners required a separate transducer and a slightly different calibration curve. Measurement accuracy was ∼3%. With the torso landmarked at the xiphoid, human adult whole‑body absorbed power varied approximately linearly with patient weight and BMI. This indicates that whole-body torso SAR is on average

  20. InSAR Scientific Computing Environment on the Cloud

    NASA Astrophysics Data System (ADS)

    Rosen, P. A.; Shams, K. S.; Gurrola, E. M.; George, B. A.; Knight, D. S.

    2012-12-01

    In response to the needs of the international scientific and operational Earth observation communities, spaceborne Synthetic Aperture Radar (SAR) systems are being tasked to produce enormous volumes of raw data daily, with availability to scientists to increase substantially as more satellites come online and data becomes more accessible through more open data policies. The availability of these unprecedentedly dense and rich datasets has led to the development of sophisticated algorithms that can take advantage of them. In particular, interferometric time series analysis of SAR data provides insights into the changing earth and requires substantial computational power to process data across large regions and over large time periods. This poses challenges for existing infrastructure, software, and techniques required to process, store, and deliver the results to the global community of scientists. The current state-of-the-art solutions employ traditional data storage and processing applications that require download of data to the local repositories before processing. This approach is becoming untenable in light of the enormous volume of data that must be processed in an iterative and collaborative manner. We have analyzed and tested new cloud computing and virtualization approaches to address these challenges within the context of InSAR in the earth science community. Cloud computing is democratizing computational and storage capabilities for science users across the world. The NASA Jet Propulsion Laboratory has been an early adopter of this technology, successfully integrating cloud computing in a variety of production applications ranging from mission operations to downlink data processing. We have ported a new InSAR processing suite called ISCE (InSAR Scientific Computing Environment) to a scalable distributed system running in the Amazon GovCloud to demonstrate the efficacy of cloud computing for this application. We have integrated ISCE with Polyphony to

  1. Neural techniques for SAR intensity and coherence data classificataion

    NASA Astrophysics Data System (ADS)

    Blonda, Palma N.; Satalino, Giuseppe; Wasowski, Janusz; Parise, Mario; Baraldi, Alberto; Refice, Alberto

    1999-12-01

    In recent years it has been proved that combined analysis of SAR intensity and interferometric correlation images is a valuable tool in classification tasks where traditional techniques such as crisp thresholding schemes and classical maximum likelihood classifiers have been employed. In this work, developed in the framework of the ESA AO3-320 project titled Application of ERS data to landslide activity monitoring in southern Apennines, Italy, our goal is to investigate: (1) usefulness of SAR interferometric correlation information in mapping areas with diffuse erosional activity, including landslides; and (2) effectiveness of soft computing techniques in the combined analysis of SAR intensity and interferometric correlation images. Two neural classifiers are selected from the literature. The first classifier is a one- stage error-driven Multilayer Perceptron (MLP) and the second classifier is a Two-Stage Hybrid (TSH) learning system, consisting of a sequence of an unsupervised data-driven first stage with a supervised error-driven second stage. The TSH unsupervised first stage is implemented as either: (1) the on- line learning, dynamic-sizing, dynamic-linking Fully Self Organizing Simplified Adaptive Resonance Theory (FOSART) clustering model; (2) the batch-learning, static-sizing, no- linking Fuzzy Learning Vector Quantization (FLVQ) algorithm; or (3) the on-line learning, static-sizing, static-linking Self-Organizing Map (SOM). The input data set consists of three SAR ERS-1/ERS-2 tandem pair images depicting an area featuring slope instability phenomena in the Campanian Apennines of Southern Italy. From each tandem pair, four pixel-based features are extracted: the backscattering mean intensity, the interferometric coherence, the backscattering intensity texture and the backscattering intensity change. Our classification task is focused on the discrimination of land cover types useful for hazard evaluation, i.e., evaluation of areas affected by erosion

  2. SAR Altimetry in Coastal Zone: Performances, Limits, Perspectives

    NASA Astrophysics Data System (ADS)

    Dinardo, S.; Benveniste, J.

    2011-12-01

    Up to now, any effort to retrieve the coastal zone phenomena from the space has been hindered by the intrinsic incapacity of conventional radar altimeters to sample all but largest scales involved in the coastal processes due to its insufficient along- track resolution. However, nowadays, a new technology in Space-borne Altimetry has become reality: the Synthetic Aperture Radar (SAR) Altimeter. The acquisition of altimetric data in SAR mode ensures a higher resolving measurement power that shall enable scientists for the first time to aspire to measure even short-scale weak coastal phenomena, thanks to the 20- fold smaller along track radar resolution and 10 dB higher Signal to Noise ratio. The secondary, but significant in coastal zone, effect of the radar footprint shrinking is the expected reduced impact of land contamination on the radar waveforms in the proximity of the shore. As a consequence of this effect, the advent of SAR focusing promises to bring the satellite altimetry remote sensing closer to the shore up to around 500 meters. Anyway, this lower bound of 500 meter on coastal proximity is not always reachable, as the footprint shrinking occurs only in along track direction while the across track resolution shall remain basically unaltered. Hence, the orientation of the satellite ground-track with respect the coastline plays a role crucial for an effective filtering out of the off-nadir land-originated signals. In the present work, utilizing the current CryoSat-2 Altimeter Dataset (SAR L1b) acquired over coastal sea water, and by retracking the SAR L1b waveforms, a performances study of SAR altimetry in coastal zone will be addressed and the benefits and limits of this new technology highlighted. As particular study area, the Tyrrhenian Sea has been selected: statistics and metrics for sea surface height and significant wave height, as calculated from a cycle of passes, will be assessed, shown and interpreted. Finally, employing the Cryo

  3. An RF dosimeter for independent SAR measurement in MRI scanners

    SciTech Connect

    Qian, Di; Bottomley, Paul A.; El-Sharkawy, AbdEl-Monem M.; Edelstein, William A.

    2013-12-15

    Purpose: The monitoring and management of radio frequency (RF) exposure is critical for ensuring magnetic resonance imaging (MRI) safety. Commercial MRI scanners can overestimate specific absorption rates (SAR) and improperly restrict clinical MRI scans or the application of new MRI sequences, while underestimation of SAR can lead to tissue heating and thermal injury. Accurate scanner-independent RF dosimetry is essential for measuring actual exposure when SAR is critical for ensuring regulatory compliance and MRI safety, for establishing RF exposure while evaluating interventional leads and devices, and for routine MRI quality assessment by medical physicists. However, at present there are no scanner-independent SAR dosimeters. Methods: An SAR dosimeter with an RF transducer comprises two orthogonal, rectangular copper loops and a spherical MRI phantom. The transducer is placed in the magnet bore and calibrated to approximate the resistive loading of the scanner's whole-body birdcage RF coil for human subjects in Philips, GE and Siemens 3 tesla (3T) MRI scanners. The transducer loop reactances are adjusted to minimize interference with the transmit RF field (B{sub 1}) at the MRI frequency. Power from the RF transducer is sampled with a high dynamic range power monitor and recorded on a computer. The deposited power is calibrated and tested on eight different MRI scanners. Whole-body absorbed power vs weight and body mass index (BMI) is measured directly on 26 subjects. Results: A single linear calibration curve sufficed for RF dosimetry at 127.8 MHz on three different Philips and three GE 3T MRI scanners. An RF dosimeter operating at 123.2 MHz on two Siemens 3T scanners required a separate transducer and a slightly different calibration curve. Measurement accuracy was ∼3%. With the torso landmarked at the xiphoid, human adult whole‑body absorbed power varied approximately linearly with patient weight and BMI. This indicates that whole-body torso SAR is on

  4. Evaluation of the operational SAR based Baltic Sea ice concentration products

    NASA Astrophysics Data System (ADS)

    Karvonen, Juha

    2015-07-01

    Sea ice concentration is an important ice parameter both for weather and climate modeling and sea ice navigation. We have developed an fully automated algorithm for sea ice concentration retrieval using dual-polarized ScanSAR wide mode RADARSAT-2 data. RADARSAT-2 is a C-band SAR (Synthetic Aperture Radar) instrument enabling dual-polarized acquisition in ScanSAR mode. The swath width for the RADARSAT-2 ScanSAR mode is about 500 km, making it very suitable for operational sea ice monitoring. The polarization combination used in our concentration estimation is HH/HV. The SAR data is first preprocessed; the preprocessing consists of geo-rectification to Mercator projection, incidence angle correction for both the polarization channels, and SAR mosaicking. After preprocessing a segmentation is performed for the SAR mosaics, and some features are computed for each SAR segment. Finally the SAR concentration is estimated based on these segment-wise features. The algorithm is basically similar as introduced in Karvonen 2014. The ice concentration is computed daily using a daily RADARSAT-2 SAR mosaic as its input, and it thus gives the concentration estimated at each grid cell (pixel) based on the most recent SAR data at the location. The algorithm has been run in an operational test mode since January 2014. We present evaluation of the SAR-based concentration estimates for the Baltic ice season 2014 by comparing the SAR results with gridded Finnish Meteorological Institute (FMI) ice charts and ice concentration estimates from a radiometer algorithm.

  5. Centimeter range measurement using amplitude data of TerraSAR-X imagery

    NASA Astrophysics Data System (ADS)

    Capaldo, P.; Fratarcangeli, F.; Nascetti, A.; Mazzoni, A.; Porfiri, M.; Crespi, M.

    2014-09-01

    The SAR (Synthetic Aperture Radar) imagery are largely used for the environmental, structures and infrastructures monitoring. In particular, Differential SAR Interferometry (DInSAR) is a well known technique that allows producing spatially dense displacement maps with centimetre to millimetre accuracy. The SAR signal is characterized by phase and amplitude value and the DInSAR remote sensing technique allows to analyse deformation phenomena affecting both extended natural areas and localized man-made structures, by exploiting the phase difference of SAR image pairs. New SAR satellite sensors such as COSMO-SkyMed, TerraSAR-X and PAZ offer the capability to achieve positioning in a global reference frame accuracies in the meter range and even better, thanks to the higher image resolution (up to 0.20 m pixel resolution in the Staring SpotLight mode for TerraSAR-X and PAZ) and to the use of on board dual frequency GPS receivers, which allows to determine the satellite orbit with an accuracy at few centimetres level. The goal of this work is to exploit the slant-range measurements reaching centimetre accuracies using only the amplitude information of SAR images acquired by TerraSAR-X satellite sensor. The leading idea is to evaluate the positioning accuracy of well identifiable and stable natural and man-made Persistent Scatterers (PS's) along the SAR line of sight. The preliminary results, obtained on the Berlin area (Germany), shown that it is possible achieve a slant-range positioning accuracy with a bias well below 10 cm and a standard deviation of about 3 cm; the results are encouraging for applications of high resolution SAR imagery amplitude data in land and infrastructures monitoring.

  6. Comparison of High Resolution Topographic Data Sources (SAR, IfSAR, and LiDAR) for Storm Surge Hazard Maps

    NASA Astrophysics Data System (ADS)

    Suarez, J. K. B.; Santiago, J. T.; Muldong, T. M. M.; Lagmay, A. M. A.; Caro, C. V.; Ramos, M.

    2014-12-01

    As an archipelagic country, the Philippines has experienced multiple storm surge threats. Moreover, the country's location, adjacent to the Pacific Ocean, results in an average of eight to nine typhoons that make landfall in a year. Storm surge hazard maps require high resolution topographic data to illustrate water inflow in the event of storm surges in vulnerable coastal areas and for accurate boundaries and coastline. Furthermore, potential hazard areas tend to be generalized in lower resolution data. The objective of this research is to compare three sources where accurate and quality storm surge hazard maps will draw bases from. For this purpose, the researcher used and compared SAR, IfSAR and LiDAR. The study involved comparing maps from different topographic data sources in Tacloban, in the province of Leyte. This area was one of the most heavily stricken areas during typhoon Haiyan where more than 6,000 people died and P34.37 billion worth of property was destroyed. In the comparison of the three sources, the following had be taken into consideration: cost of acquiring data, processing time, purpose, and the results. The research learned the following: Synthetic Aperture Radar or SAR produces data with a 30 meter resolution, while Interferometric Synthetic Aperture Radar (IfSAR) offers a resolution of 5 meters. Light Detection and Ranging (LiDAR) has the highest resolution of the three with 1 meter. In addition, higher costs are paid for more detailed topographic data. Also, processing time takes longer for finer details due to the memory of the computer units used for modelling. The sources were also evaluated on the necessity of the scale at which the maps are needed for specific purposes such as practicality and direct disaster response. Results from the maps have been validated through interviews with the locals on the experience of actual storm surges. Through this study, the researcher concluded that although LiDAR can offer a more detailed and

  7. Application of SAR interferometry in Grove Mountains, east Antarctica

    NASA Astrophysics Data System (ADS)

    E, Dongchen; Zhou, Chunxia; Liao, Mingsheng

    2004-02-01

    Synthetic aperture radar interferometry has been proposed as a potential technique for digital elevation model (DEM) generation, topographic mapping, and surface motion detection especially in the inaccessible areas. Grove Mountains Area locates to the southwest of Princess Elizabeth Land, inland areas of east Antarctica. The topographical map of the core area (11 x 10 KM2) was printed after the field surveying with GPS and total station was finished under the atrocious weather conditions during the 16th CHINARE (Chinese National Antarctic Research Expedition) 1999/2000. This paper will present an experimental investigation of the ERS-1/2 SAR tandem data in 1996 on DEM generation of the Grove Mountains Core Area, analyze the data processing, and compare the DEM with the actual topographic form. It is confirmed that InSAR is a very useful technique to be utilized in Antarctica, and can be used to produce more products instead of dagnerous field surveying.

  8. Custom large scale integrated circuits for spaceborne SAR processors

    NASA Technical Reports Server (NTRS)

    Tyree, V. C.

    1978-01-01

    The application of modern LSI technology to the development of a time-domain azimuth correlator for SAR processing is discussed. General design requirements for azimuth correlators for missions such as SEASAT-A, Venus orbital imaging radar (VOIR), and shuttle imaging radar (SIR) are summarized. Several azimuth correlator architectures that are suitable for implementation using custom LSI devices are described. Technical factors pertaining to selection of appropriate LSI technologies are discussed, and the maturity of alternative technologies for spacecraft applications are reported in the context of expected space mission launch dates. The preliminary design of a custom LSI time-domain azimuth correlator device (ACD) being developed for use in future SAR processors is detailed.

  9. Preliminary analysis of ERS-1 SAR for forest ecosystem studies

    NASA Technical Reports Server (NTRS)

    Dobson, M. G.; Pierce, Leland; Sarabandi, Kamal; Ulaby, Fawwaz T.; Sharik, Terry

    1992-01-01

    An image obtained by the C-band VV-polarized ERS-1 SAR is examined with respect to potential land applications. A scene obtained near noon on August 15, 1991, along the U.S.-Canadian border near Sault Ste. Marie is calibrated relative to an array of trihedral corner reflectors and active radar calibrators distributed across the swath. Extensive contemporaneous ground observations of forest stands are used to predict the radar backscattering coefficient sigma at the time of the SAR overpass using a first-order vector radiative transfer model. These predictions generally agree with the calibrated ERS-1 data to within 1 dB. It is demonstrated that the dynamic range of sigma is sufficient to perform limited discrimination of various forest and grassland communities even for a single-date observation. Furthermore, retrieval of near-surface soil moisture is feasible for grass-covered soils when plant biomass is less than 1 tonne/ha.

  10. The Danish SAR system - Design and initial tests

    NASA Technical Reports Server (NTRS)

    Madsen, Soren N.; Christensen, Erik L.; Skou, Niels; Dall, Jorgen

    1991-01-01

    In January 1986, the design of a high-resolution airborne C-band SAR started at the Electromagnetics Institute of the Technical University of Denmark. The initial system test flights took place in November and December 1989. The authors describe the design of the system, its implementation, and its performance. They show how digital technology has been utilized to realize a very flexible radar with variable resolution, swath-width, and imaging geometry. The motion-compensation algorithms implemented to obtain the high resolution and the special features built into the system to ensure proper internal calibration are outlined. The data processing system, developed for image generation and quality assurance, is sketched, with special emphasis on the flexibility of the system. Sample images and a preliminary performance evaluation are presented, demonstrating that the design goals have been met. The ongoing system upgrades and the planned scientific utilization of the C-band SAR are described.

  11. CASMSAR: the first Chinese airborne SAR mapping system

    NASA Astrophysics Data System (ADS)

    Zhang, Jixian; Wang, Zhang; Huang, Guoman; Zhao, Zheng; Lu, Lijun

    2010-09-01

    In this paper, we present an overall description of the newest Chinese airborne SAR mapping system CASMSAR, which is developed by a group led by Chinese Academy of Surveying and Mapping (CASM). Since CASMSAR is equipped with two independent high-resolution SAR sensors (X-band and P-band), it allows the integration of interferometric and fully polarimetric functions. Another novel feature of CASMSAR is the software control of system monitoring and flight navigation display, which makes the whole system very intelligent and operational. The data processing software systems of CASMSAR consists of five subsystems. CASMSAR works in several modes. The most important two of them are used for mapping in scale of 1:10,000 and 1:50,000. Initial data were acquired during several testing flight campaigns in last year, and experimental results have proved that the system works well and the performance is better than expectation.

  12. SARS and MERS: recent insights into emerging coronaviruses.

    PubMed

    de Wit, Emmie; van Doremalen, Neeltje; Falzarano, Darryl; Munster, Vincent J

    2016-08-01

    The emergence of Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012 marked the second introduction of a highly pathogenic coronavirus into the human population in the twenty-first century. The continuing introductions of MERS-CoV from dromedary camels, the subsequent travel-related viral spread, the unprecedented nosocomial outbreaks and the high case-fatality rates highlight the need for prophylactic and therapeutic measures. Scientific advancements since the 2002-2003 severe acute respiratory syndrome coronavirus (SARS-CoV) pandemic allowed for rapid progress in our understanding of the epidemiology and pathogenesis of MERS-CoV and the development of therapeutics. In this Review, we detail our present understanding of the transmission and pathogenesis of SARS-CoV and MERS-CoV, and discuss the current state of development of measures to combat emerging coronaviruses. PMID:27344959

  13. Seasat SAR identification of dry climate urban land cover

    NASA Technical Reports Server (NTRS)

    Henderson, F. M.; Wharton, S. W.

    1980-01-01

    Digitally processed Seasat synthetic aperture radar (SAR) imagery of the Denver, Colorado area was examined to assess its potential for mapping urban land cover and the compatibility of SAR derived classes with those described in the U.S. Geological Survey classification system. The entire scene was interpreted to generate a small-scale land cover map. In addition, six subscene enlargements representative of urban land cover categories extant in the area were used as test sites for detailed analysis of land cover types. Two distinct approaches were employed and compared in examining the imagery - a visual interpretation of black-and-white positive transparencies and an automated-machine/visual interpretation. The latter used the Image 100 interactive image analysis system to generate land cover classes by density level slicing of the image frequency histogram.

  14. Multiscale Segmentation of Polarimetric SAR Image Based on Srm Superpixels

    NASA Astrophysics Data System (ADS)

    Lang, F.; Yang, J.; Wu, L.; Li, D.

    2016-06-01

    Multi-scale segmentation of remote sensing image is more systematic and more convenient for the object-oriented image analysis compared to single-scale segmentation. However, the existing pixel-based polarimetric SAR (PolSAR) image multi-scale segmentation algorithms are usually inefficient and impractical. In this paper, we proposed a superpixel-based binary partition tree (BPT) segmentation algorithm by combining the generalized statistical region merging (GSRM) algorithm and the BPT algorithm. First, superpixels are obtained by setting a maximum region number threshold to GSRM. Then, the region merging process of the BPT algorithm is implemented based on superpixels but not pixels. The proposed algorithm inherits the advantages of both GSRM and BPT. The operation efficiency is obviously improved compared to the pixel-based BPT segmentation. Experiments using the Lband ESAR image over the Oberpfaffenhofen test site proved the effectiveness of the proposed method.

  15. Ground moving target indication via multi-channel airborne SAR

    NASA Astrophysics Data System (ADS)

    Vu, Duc; Guo, Bin; Xu, Luzhou; Li, Jian

    2011-06-01

    We consider moving target detection and velocity estimation for multi-channel synthetic aperture radar (SAR) based ground moving target indication (GMTI). Via forming velocity versus cross-range images, we show that small moving targets can be detected even in the presence of strong stationary ground clutter. Furthermore, the velocities of the moving targets can be estimated, and the misplaced moving targets can be placed back to their original locations based on the estimated velocities. An iterative adaptive approach (IAA), which is robust and user parameter free, is used to form velocity versus cross-range images for each range bin of interest. Moreover, we discuss calibration techniques to combat near-field coupling problems encountered in practical systems. Furthermore, we present a sparse signal recovery approach for stationary clutter cancellation. We conclude by demonstrating the effectiveness of our approaches by using the Air Force Research Laboratory (AFRL) publicly-released Gotcha airborne SAR based GMTI data set.

  16. A new GMTI detector based on spaceborne single channel SAR

    NASA Astrophysics Data System (ADS)

    Gao, Fei; Sun, Jinping; Bai, Xia; Yu, Zhenming

    2007-11-01

    This paper examines moving targets detection using single channel Synthetic aperture radar (SAR) in spaceborne platform. Building on previous work moving targets can be retrieved from multi-look images via magnitude subtraction or phase interferometry. A more effective method is proposed which mainly consists of signal subspace processing- based data equilibrium and change detection in multi-look covariance matrix. Also different baseline is checked and weak targets may be found. Test results show that precise calibration of multi-look images are essential and short baseline is preferred when the interesting targets are weak. Therefore, the proposed method leads to improved detection performance and provides ways of GMTI in single channel SAR.

  17. (abstract) Examining Sea Ice SAR Signatures in the Arctic

    NASA Technical Reports Server (NTRS)

    Holt, Benjamin

    1993-01-01

    This research examines the seasonal changes of the sea ice cover in the Arctic Basin as it responds to atmospheric and oceanic conditions. Monitoring this process provides a means of determining the onset and extent of the annual seasonal stages, which is thought to be an indicator for detecting climate change in the polar regions. Much of the response of sea ice to seasonal conditions results in changes in the phase of water (both in the ice and snow cover), surface roughness, and internal properties such as air bubbles. Imagery from SAR has proven to be an important tool for revealing these changes since radar backscatter is affected by both surface roughness and dielectric properties of water and salt. The major ice types and ice features may have unique SAR backscatter signatures because of the inherent variations in surface roughness, salinity, and internal properties in each category.

  18. Operational wave forecasting with spaceborne SAR: Prospects and pitfalls

    NASA Technical Reports Server (NTRS)

    Beal, R. C.

    1986-01-01

    Measurements collected in the Shuttle Imaging Radar (SIR-B) Extreme Waves Experiment confirm the ability of Synthetic Aperture Radar (SAR) to yield useful estimates of wave directional energy spectra over global scales, at least for shuttle altitudes. However, azimuth fall-off effects tend to become severe for wavelengths shorter than about 100 m in most sea states. Moreover, the azimuth fall-off problem becomes increasingly severe as the platform altitude increases beyond 300 km. The most viable solution to the global wave measurements problem may be a low altitude spacecraft containing a combination of both the SAR and the Radar Ocean Wave Spectrometry (ROWS). Such a combination could have a synergy which yield global spectral estimates superior to those of either instrument singly employed.

  19. Compressive SAR imaging with joint sparsity and local similarity exploitation.

    PubMed

    Shen, Fangfang; Zhao, Guanghui; Shi, Guangming; Dong, Weisheng; Wang, Chenglong; Niu, Yi

    2015-01-01

    Compressive sensing-based synthetic aperture radar (SAR) imaging has shown its superior capability in high-resolution image formation. However, most of those works focus on the scenes that can be sparsely represented in fixed spaces. When dealing with complicated scenes, these fixed spaces lack adaptivity in characterizing varied image contents. To solve this problem, a new compressive sensing-based radar imaging approach with adaptive sparse representation is proposed. Specifically, an autoregressive model is introduced to adaptively exploit the structural sparsity of an image. In addition, similarity among pixels is integrated into the autoregressive model to further promote the capability and thus an adaptive sparse representation facilitated by a weighted autoregressive model is derived. Since the weighted autoregressive model is inherently determined by the unknown image, we propose a joint optimization scheme by iterative SAR imaging and updating of the weighted autoregressive model to solve this problem. Eventually, experimental results demonstrated the validity and generality of the proposed approach. PMID:25686307

  20. Low SAR planar antenna for multi standard cellular phones

    NASA Astrophysics Data System (ADS)

    Ben Ahmed, M.; Bouhorma, M.; Elouaai, F.; Mamouni, A.

    2011-03-01

    In this paper the design of a multiband compact antenna for the integration into the new multi function mobile phones is presented. The antenna is matched to operate at GSM 920 MHz, WI-Fi 2.4 GHz and HiperLan 5.1 GHz standards with low SAR levels. Return loss coefficient and radiation pattern of this antenna are computed in free space as well as in the presence of head. The specific absorption rate (SAR) of the planar antenna is calculated and compared with that of the monopole antenna. To examine the performance of this antenna, a prototype was designed, fabricated and measured; the simulation analysis was performed using the HFSS software, good agreement with the simulation providing validation of the design procedure.

  1. Clinical Manifestations, Laboratory Findings, and Treatment Outcomes of SARS Patients

    PubMed Central

    Wang, Jann-Tay; Sheng, Wang-Huei; Fang, Chi-Tai; Chen, Yee-Chun; Wang, Jiun-Ling; Yu, Chong-Jen; Yang, Pan-Chyr

    2004-01-01

    Clinical and laboratory data on severe acute respiratory syndrome (SARS), particularly on the temporal progression of abnormal laboratory findings, are limited. We conducted a prospective study on the clinical, radiologic, and hematologic findings of SARS patients with pneumonia, who were admitted to National Taiwan University Hospital from March 8 to June 15, 2003. Fever was the most frequent initial symptom, followed by cough, myalgia, dyspnea, and diarrhea. Twenty-four patients had various underlying diseases. Most patients had elevated C-reactive protein (CRP) levels and lymphopenia. Other common abnormal laboratory findings included leukopenia, thrombocytopenia, and elevated levels of aminotransferase, lactate dehydrogenase, and creatine kinase. These clinical and laboratory findings were exacerbated in most patients during the second week of disease. The overall case-fatality rate was 19.7%. By multivariate analysis, underlying disease and initial CRP level were predictive of death. PMID:15200814

  2. Radiometric Compensation and Calibration for Radarsat ScanSAR

    NASA Technical Reports Server (NTRS)

    Jin, Michael Y.

    1993-01-01

    Due to lack of a standard for modeling the radar echo signal in terms of signal unit and coordinates as well as lack of a standard in designing the gain factors in each stage of a processor, absolute radiometric calibration of a SAR system is usually performed by treating the sensor and processor as one inseparable unit. This often makes the calibration procedure complicated and requiring the involvement of both radar system engineers and processor engineers in the whole process. This paper introduces a standard for modeling the radar echo signal and a standard in designing the gain factor of a ScanSAR processor. In this paper, the radar equation is derived based on the amount of energy instead of the power received from a backscatterer. These efforts lead to simple and easy-to-understand equations for radiometric compensation and calibration.

  3. SAR investigations of glaciers in northwestern North America

    NASA Technical Reports Server (NTRS)

    Lingle, Craig S.; Harrison, William D.

    1995-01-01

    The objective of this project was to investigate the utility of satellite synthetic aperture radar (SAR) imagery for measurement of geophysical parameters on Alaskan glaciers relevant to their mass balance and dynamics, including: (1) the positions of firn lines (late-summer snow lines); (2) surface velocities on fast-flowing (surging) glaciers, and also on slower steady-flow glaciers; and (3) the positions and changes in the positions of glacier termini. Preliminary studies of topography and glacier surface velocity with SAR interferometry have also been carried out. This project was motivated by the relationships of multi-year to decadal changes in glacier geometry to changing climate, and the probable significant contribution of Alaskan glaciers to rising sea level.

  4. Unsupervised segmentation of polarimetric SAR data using the covariance matrix

    NASA Technical Reports Server (NTRS)

    Rignot, Eric J. M.; Chellappa, Rama; Dubois, Pascale C.

    1992-01-01

    A method for unsupervised segmentation of polarimetric synthetic aperture radar (SAR) data into classes of homogeneous microwave polarimetric backscatter characteristics is presented. Classes of polarimetric backscatter are selected on the basis of a multidimensional fuzzy clustering of the logarithm of the parameters composing the polarimetric covariance matrix. The clustering procedure uses both polarimetric amplitude and phase information, is adapted to the presence of image speckle, and does not require an arbitrary weighting of the different polarimetric channels; it also provides a partitioning of each data sample used for clustering into multiple clusters. Given the classes of polarimetric backscatter, the entire image is classified using a maximum a posteriori polarimetric classifier. Four-look polarimetric SAR complex data of lava flows and of sea ice acquired by the NASA/JPL airborne polarimetric radar (AIRSAR) are segmented using this technique. The results are discussed and compared with those obtained using supervised techniques.

  5. Estimating tropical-forest density profiles from multibaseline interferometric SAR

    NASA Technical Reports Server (NTRS)

    Treuhaft, Robert; Chapman, Bruce; dos Santos, Joao Roberto; Dutra, Luciano; Goncalves, Fabio; da Costa Freitas, Corina; Mura, Jose Claudio; de Alencastro Graca, Paulo Mauricio

    2006-01-01

    Vertical profiles of forest density are potentially robust indicators of forest biomass, fire susceptibility and ecosystem function. Tropical forests, which are among the most dense and complicated targets for remote sensing, contain about 45% of the world's biomass. Remote sensing of tropical forest structure is therefore an important component to global biomass and carbon monitoring. This paper shows preliminary results of a multibasline interfereomtric SAR (InSAR) experiment over primary, secondary, and selectively logged forests at La Selva Biological Station in Costa Rica. The profile shown results from inverse Fourier transforming 8 of the 18 baselines acquired. A profile is shown compared to lidar and field measurements. Results are highly preliminary and for qualitative assessment only. Parameter estimation will eventually replace Fourier inversion as the means to producing profiles.

  6. Effect of SAR on human head modeling inside cylindrical enclosures.

    PubMed

    Mary, T Anita Jones; Ravichandran, C S

    2013-09-01

    This study intends to discuss enclosed a realistic approach to determine and analyze the effects of radio frequency on human exposure inside a cylindrical enclosure. A scenario in which a mobile phone with inverted-F antenna (IFA) operating in the Global System for Mobile Communication (GSM) band (900 MHz) is used inside a cylindrical enclosure. Metallic enclosures are known to have resonance and reflection effects, thereby increasing electric field strength and hence resulting in a change of the human exposure to electromagnetic absorptions. So, this study examines and compares the levels of absorption in terms of specific absorption rate (SAR) values under various conditions. In this study, a human phantom with dielectric properties is designed and its interaction is studied with IFA inside fully enclosed cylindrical enclosures. The results show that SAR values are increased inside cylindrical enclosures compared with those in free space. The method of computation uses method of moments. Simulations are done in FEKO software. PMID:23323517

  7. SARS: mobilizing and maintaining a public health emergency response.

    PubMed

    Posid, Joseph M; Bruce, Sherrie M; Guarnizo, Julie T; Taylor, Melissa L; Garza, Brenda W

    2005-01-01

    During the spring and summer of 2003, the Centers for Disease Control and Prevention (CDC) mobilized the resources of the entire agency in a concerted effort to meet the challenges posed by the outbreak of Severe Acute Respiratory Syndrome (SARS). Over the 133 days that comprised the emergency response phase of the SARS outbreak, CDC utilized the skills of more than 850 people. These staff were deployed from every Center, Institute, and Office within CDC and the Agency for Toxic Substances and Disease Registry. They provided technical assistance to countries reporting large numbers of cases and requesting assistance, met passengers and crew from these locations upon arrival in the United States, and assured that the syndrome was reported and thoroughly investigated within the United States. This paper describes the operational requirements that were established and the resources that were used to conduct this investigation. PMID:15829833

  8. The discrimination of sea ice types using SAR backscatter statistics

    NASA Technical Reports Server (NTRS)

    Shuchman, Robert A.; Wackerman, Christopher C.; Maffett, Andrew L.; Onstott, Robert G.; Sutherland, Laura L.

    1989-01-01

    X-band (HH) synthetic aperture radar (SAR) data of sea ice collected during the Marginal Ice Zone Experiment in March and April of 1987 was statistically analyzed with respect to discriminating open water, first-year ice, multiyear ice, and Odden. Odden are large expanses of nilas ice that rapidly form in the Greenland Sea and transform into pancake ice. A first-order statistical analysis indicated that mean versus variance can segment out open water and first-year ice, and skewness versus modified skewness can segment the Odden and multilayer categories. In additions to first-order statistics, a model has been generated for the distribution function of the SAR ice data. Segmentation of ice types was also attempted using textural measurements. In this case, the general co-occurency matrix was evaluated. The textural method did not generate better results than the first-order statistical approach.

  9. Initial assessment of an airborne Ku-band polarimetric SAR.

    SciTech Connect

    Raynal, Ann Marie; Doerry, Armin Walter

    2013-02-01

    Polarimetric synthetic aperture radar (SAR) has been used for a variety of dual-use research applications since the 1940's. By measuring the direction of the electric field vector from radar echoes, polarimetry may enhance an analyst's understanding of scattering effects for both earth monitoring and tactical surveillance missions. Polarimetry may provide insight into surface types, materials, or orientations for natural and man-made targets. Polarimetric measurements may also be used to enhance the contrast between scattering surfaces such as man-made objects and their surroundings. This report represents an initial assessment of the utility of, and applications for, polarimetric SAR at Ku-band for airborne or unmanned aerial systems.

  10. Assessment of slope stability using PS-InSAR technique

    NASA Astrophysics Data System (ADS)

    Dwivedi, R.; Varshney, P.; Tiwari, A.; Singh, A. K.; Dikshit, O.

    2014-11-01

    In this research work, PS-InSAR approach is envisaged to monitor slope stability of landslides prone areas in Nainital and Tehri region of Uttarakhand, India. For the proposed work, Stanford Method for Persistent Scatterers (StaMPS) based PS-InSAR is used for processing ENVISAT ASAR C-Band data stacks of study area which resulted in a time series 1D-Line of Sight (LOS) map of surface displacement. StaMPS efficiently extracted the PS pixels on the unstable slopes in both areas and the time series 1D-LOS displacement map of PS pixels indicates that those areas in Nainital and Tehri region have measurement pixels with maximum displacement away from the satellite of the order of 22 mm/year and 17.6 mm/year respectively

  11. Unsupervised segmentation of polarimetric SAR data using the covariance matrix

    NASA Technical Reports Server (NTRS)

    Rignot, Eric; Chellappa, Rama; Dubois, Pascale; Kwok, Ronald; Van Zyl, Jacob

    1991-01-01

    An unsupervised selection of polarimetric features useful for the segmentation and analysis of polarimetric synthetic aperture radar (SAR) data is presented. The technique is based on multidimensional clustering of the parameters composing the polarimetric covariance matrix of the data. Clustering is performed on the logarithm of these quantities. Once the polarimetric cluster centers have been determined, segmentation of the polarimetric data into regions is performed using a maximum likelihood polarimetric classifier. Segmentation maps are further improved using a Markov random field to describe the statistics of the regions and computing the maximum of the product of the local conditional densities. Examples with real polarimetric SAR imagery are given to illustrate the potential of this method.

  12. Intelligent low rate compression of speckled SAR imagery

    SciTech Connect

    Ives, R.W.; Eichel, P.; Magotra, N.

    1997-05-01

    This paper describes a compression technique under development at Sandia National Laboratories for the compression of complex synthetic aperture radar (SAR) imagery at very low overall bit rates. The methods involved combine several elements of existing and new lossy and lossless compression schemes in order to achieve an overall compression ratio of large SAR scenes of at least 50:1, while maintaining reasonable image quality. It is assumed that the end user will be primarily interested in specific regions of interest within the image (called chips), but that the context in which these chips appear within the entire scene is also of importance to an image analyst. The term intelligent is used to signify an external cuer which locates the chips of interest.

  13. Rapid subsidence over oil fields measured by SAR

    NASA Technical Reports Server (NTRS)

    Fielding, E. J.; Blom, R. G.; Goldstein, R. M.

    1998-01-01

    The Lost Hills and Belridge oil felds are in the San Joaquin Valley, California. The major oil reservoir is high porosity and low permeability diatomite. Extraction of large volumes from shallow depths causes reduction in pore pressure and subsequent compaction, forming a surface subsidence bowl. We measure this subsidence from space using interferometric analysis of SAR (Synthetic Aperture Radar) data collected by the European Space Agency Remote Sensing Satellites (ERS-1 and ERS-2). Maximum subsidence rates are as high as 40 mm in 35 days or > 400 mm/yr, measured from interferograms with time separations ranging from one day to 26 months. The 8- and 26-month interferograms contain areas where the subsidence gradient exceeds the measurement possible with ERS SAR, but shows increased detail in areas of less rapid subsidence. Synoptic mapping of subsidence distribution from satellite data powerfully complements ground-based techniques, permits measurements where access is difficult, and aids identification of underlying causes.

  14. InSAR observations of the 2007 Pisco, Peru earthquake.

    NASA Astrophysics Data System (ADS)

    Biggs, J.; Dixon, T.; Amelung, F.

    2008-05-01

    InSAR is a powerful tool for studying large earthquakes since it gives a spatially dense surface displacement field. We use data from three different satellites: Envisat, ERS-2 and ALOS, each with different characteristics. Envisat and ERS-2 are C-band satellites (wavelength, l=5.6 cm) operated by the European Space Agency and ALOS is a Japanese satellite with an L-band SAR (l=23.6 cm). Differences in the timing of availability of radar images from each satellite mean they cover different periods of the earthquake cycle and measure the surface displacement field in along different line-of-sight vectors. We combine these observations to produce a model of the slip distribution on the subduction interface and find a single asperity centred under the Paracas Penninsula. This corresponds to the second of two asperities identified by the inversion of seimic waveforms.

  15. GNSS-based bistatic SAR: a signal processing view

    NASA Astrophysics Data System (ADS)

    Antoniou, Michail; Cherniakov, Mikhail

    2013-12-01

    This article presents signal processing algorithms used as a new remote sensing tool, that is passive bistatic SAR with navigation satellites (e.g. GPS, GLONASS or Galileo) as transmitters of opportunity. Signal synchronisation and image formation algorithms are described for two system variants: one where the receiver is moving and one where it is fixed on the ground. The applicability and functionality of the algorithms described is demonstrated through experimental imagery that ultimately confirms the feasibility of the overall technology.

  16. Synthesis, SAR and antibacterial studies on novel chalcone oxazolidinone hybrids.

    PubMed

    Selvakumar, N; Kumar, G Sunil; Azhagan, A Malar; Rajulu, G Govinda; Sharma, Shikha; Kumar, M Sitaram; Das, Jagattaran; Iqbal, Javed; Trehan, Sanjay

    2007-04-01

    With an intention to synergise the antibacterial activity of chalcones and oxazolidinones, several hybrid compounds possessing both chalcone and oxazolidinone moieties were synthesized and tested for antibacterial activity. The hybrid molecules containing heterocycles instead of aromatic ring were found to be active. A SAR study with various heterocycles resulted in a lead molecule 20, which was converted to one of the potent antibacterial compounds 27. PMID:17150281

  17. SAR image change detection using watershed and spectral clustering

    NASA Astrophysics Data System (ADS)

    Niu, Ruican; Jiao, L. C.; Wang, Guiting; Feng, Jie

    2011-12-01

    A new method of change detection in SAR images based on spectral clustering is presented in this paper. Spectral clustering is employed to extract change information from a pair images acquired on the same geographical area at different time. Watershed transform is applied to initially segment the big image into non-overlapped local regions, leading to reduce the complexity. Experiments results and system analysis confirm the effectiveness of the proposed algorithm.

  18. Enhancement on spotlight COSMO-SkyMed SAR products

    NASA Astrophysics Data System (ADS)

    Lorusso, R.; Milillo, G.

    2015-10-01

    COSMO-SkyMed (CSK) satellites are providing images with a resolution in the meter regime using the sliding spotlight mode (SL). This is an imaging mode which can obtain better azimuth resolution at the expense of azimuth imaged area than stripmap mode .Spotlight SAR data processing is already an established topic; efficient and accurate solutions in frequency domain have been proposed over the last years. However, the assumptions of these algorithms start to be invalid when applied to high-resolution spotlight SAR data acquired in spaceborne low Earth orbit (LEO) configurations. The assumption of a hyperbolic range history is no longer accurate for sub-metric spatial resolutions due to the satellite curved orbit. Since velocity of a space-borne platform is quite uniform, a simple focusing scheme had been designed in order to handle no straight line trajectory, using both approximated and accurate ω-k focusing kernel. Moreover, when getting close to decimeter resolution (at X-band) other several effects appear; in particular the motion of the satellite during the transmission and reception of the chirp signal deteriorate the impulse response function (IRF), if not properly considered (so called stop-and-go approximation). This paper shows that also CSK SL SAR data, with a resolution close to 1 meter, are not immune to disturbance effects when the stop-and-go approximation is assumed. The ω-k algorithm with satellite curved orbit handling is used to focus CSK spotlight data, and the stop-and-go approximation correction is included in the data processing chain. Experimental results with CSK spotlight data are provided to show quality enhancement on SAR standard focused products.

  19. Coastal and Wetlands Applications for an InSAR Mission

    NASA Astrophysics Data System (ADS)

    Dixon, T.; Amelung, F.; Gourmelen, N.; Kim, S.; Osmanoglu, B.; Wdowinski, S.

    2006-12-01

    Interferometric Synthetic Aperture Radar (InSAR) has found wide application in the study of Earth surface change, including earthquake and volcano deformation, motion of glaciers and ice sheets, and ground subsidence due to fluid extraction. In the last few years, InSAR may have significant application in studies of wetlands, coastal regions, and related environmental problems. These are becoming increasingly important as global warming contributes to sea level rise, with consequent modification or loss of coastal habitat, and increased storm frequency/intensity, with consequent increased hazard to coastal communities. Most of these applications would benefit from increased data availability and spatial resolution. A common problem for many InSAR studies in these areas is the influence of spatially and temporally variable tropospheric water vapor. Multiple interferograms can be used to average down tropospheric noise, or selectively edit image pairs where tropospheric noise is high. Alternately, the Permanent Scatterer (PSInSAR) technique can produce an average surface change rate over several months or years for coastal land applications where the assumption of steady state deformation is reasonable (e.g., some land subsidence applications). This technique also effectively identifies tropospheric noise. Common to both approaches is the need for large numbers of images, closely spaced in time. Wetland water levels also change on short time scales (days to weeks) implying the need for frequent coverage. Hence, such applications benefit from mission scenarios emphasizing repeat times shorter than 7 days. Assuming global coverage is desirable, the requirement for rapid re-survey suggests that multi-satellite constellations should be considered.

  20. Application of postured human model for SAR measurements

    NASA Astrophysics Data System (ADS)

    Vuchkovikj, M.; Munteanu, I.; Weiland, T.

    2013-07-01

    In the last two decades, the increasing number of electronic devices used in day-to-day life led to a growing interest in the study of the electromagnetic field interaction with biological tissues. The design of medical devices and wireless communication devices such as mobile phones benefits a lot from the bio-electromagnetic simulations in which digital human models are used. The digital human models currently available have an upright position which limits the research activities in realistic scenarios, where postured human bodies must be considered. For this reason, a software application called "BodyFlex for CST STUDIO SUITE" was developed. In its current version, this application can deform the voxel-based human model named HUGO (Dipp GmbH, 2010) to allow the generation of common postures that people use in normal life, ensuring the continuity of tissues and conserving the mass to an acceptable level. This paper describes the enhancement of the "BodyFlex" application, which is related to the movements of the forearm and the wrist of a digital human model. One of the electromagnetic applications in which the forearm and the wrist movement of a voxel based human model has a significant meaning is the measurement of the specific absorption rate (SAR) when a model is exposed to a radio frequency electromagnetic field produced by a mobile phone. Current SAR measurements of the exposure from mobile phones are performed with the SAM (Specific Anthropomorphic Mannequin) phantom which is filled with a dispersive but homogeneous material. We are interested what happens with the SAR values if a realistic inhomogeneous human model is used. To this aim, two human models, a homogeneous and an inhomogeneous one, in two simulation scenarios are used, in order to examine and observe the differences in the results for the SAR values.

  1. Reflectors for SAR performance testing-second edition

    SciTech Connect

    Doerry, Armin Walter

    2014-02-01

    Synthetic Aperture Radar (SAR) performance testing and estimation is facilitated by observing the system response to known target scene elements. Trihedral corner reflectors and other canonical targets play an important role because their Radar Cross Section (RCS) can be calculated analytically. However, reflector orientation and the proximity of the ground and mounting structures can significantly impact the accuracy and precision with which measurements can be made. These issues are examined in this report.

  2. Interferometric SAR imaging by transmitting stepped frequency chaotic noise signals

    NASA Astrophysics Data System (ADS)

    Zhang, Yunhua; Gu, Xiang; Zhai, Wenshuai; Dong, Xiao; Shi, Xiaojin; Kang, Xueyan

    2015-10-01

    Noise radar has been applied in many fields since it was proposed more than 50 years ago. However, it has not been applied to interferometric SAR imaging yet as far as we know. This paper introduces our recent work on interferometric noise radar. An interferometric SAR system was developed which can transmit both chirp signal and chaotic noise signal (CNS) at multiple carrier frequencies. An airborne experiment with this system by transmitting both signals was carried out, and the data were processed to show the capability of interferometric SAR imaging with CNS. The results shows that although the interferometric phase quality of CNS is degraded due to the signal to noise ratio (SNR) is lower compared with that of chirp signal, we still can get satisfied DEM after multi-looking processing. Another work of this paper is to apply compressed sensing (CS) theory to the interferometric SAR imaging with CNS. The CS theory states that if a signal is sparse, then it can be accurately reconstructed with much less sampled data than that regularly required according to Nyquist Sampling Theory. To form a structured random matrix, if the transmitted signal is of fixed waveform, then random subsampling is needed. However, if the transmitted signal is of random waveform, then only uniform subsampling is needed. This is another advantage of noise signal. Both the interferometric phase images and the DEMs by regular method and by CS method are processed with results compared. It is shown that the degradation of interferometric phases due to subsampling is larger than that of amplitude image.

  3. A low-power SAR ADC for IRFPA ROIC

    NASA Astrophysics Data System (ADS)

    Gao, Lei; Ding, Ruijun; Zhou, Jie; Wang, Pan; Chen, Guoqiang

    2012-12-01

    This paper presents a low power ADC for the 512*512 infrared focal plane arrays (IRFPA) readout integrated circuit(ROIC). The major structure, the working mode and the simulation result of the readout integrated circuit are shown in this paper. The power supply voltage of 0.35μm standard CMOS process is 3.3V in this design, and then the output range of the Direct Injection (DI) input circuit is reached 2V. Successive-approximation-register (SAR) ADC architecture is used in this readout integrated circuit. And each ADC is shared by one column of the IRFPA. This SAR ADC is made up of a 13-bit digital-analog converter (DAC), a high resolution comparator, and a digital control circuit. The most important part is the voltage-scaling and charge-scaling charge redistribution DAC. In this DAC, charge scaling with a capacitor ladder to determine the least significant bits is combined with voltage scaling with a resister ladder to determine the most significant bits. The comparator uses three-stage operational amplifier structure to get a 77dB differential gain. The Common-Mode input rang of the comparator is 1V to 3V, and minimum resolvable voltage difference is 0.3mV. This SAR ADC has some advantages, especially in low power and high speed. The simulation result shows that the resolution of the ADC is 12 bit and the conversion time of the ADC is 6.5μs, while the power of each ADC is as low as 300μW. Finally, this SAR ADC can satisfy the request of 512*512 IRFPAs ROIC with a 100Hz frame rate.

  4. Modeling and public health emergency responses: lessons from SARS.

    PubMed

    Glasser, John W; Hupert, Nathaniel; McCauley, Mary M; Hatchett, Richard

    2011-03-01

    Modelers published thoughtful articles after the 2003 SARS crisis, but had limited if any real-time impact on the global response and may even have inadvertently contributed to a lingering misunderstanding of the means by which the epidemic was controlled. The impact of any intervention depends on its efficiency as well as efficacy, and efficient isolation of infected individuals before they become symptomatic is difficult to imagine. Nonetheless, in exploring the possible impact of quarantine, the product of efficiency and efficacy was varied over the entire unit interval. Another mistake was repeatedly fitting otherwise appropriate gamma distributions to times to event regardless of whether they were stationary or not, particularly onset-isolation intervals whose progressive reduction evidently contributed to SARS control. By virtue of their unknown biology, newly-emerging diseases are more challenging than familiar human scourges. Influenza, for example, recurs annually and has been modeled more thoroughly than any other infectious disease. Moreover, models were integrated into preparedness exercises, during which working relationships were established that bore fruit during the 2009 A/H1N1 pandemic. To provide the most accurate and timely advice possible, especially about the possible impact of measures designed to control diseases caused by novel human pathogens, we must appreciate the value and difficulty of policy-oriented modeling. Effective communication of insights gleaned from modeling SARS will help to ensure that policymakers involve modelers in future outbreaks of newly-emerging infectious diseases. Accordingly, we illustrate the increasingly timely care-seeking by which, together with increasingly accurate diagnoses and effective isolation, SARS was controlled via heuristic arguments and descriptive analyses of familiar observations. PMID:21420657

  5. MAPSAR: a small L-band SAR mission for land observation

    NASA Astrophysics Data System (ADS)

    Schröder, Reinhard; Puls, Jürgen; Hajnsek, Irena; Jochim, Fritz; Neff, Thomas; Kono, Janio; Renato Paradella, Waldir; Marcos Quintino da Silva, Mario; de Morisson Valeriano, Dalton; Pereira Farias Costa, Maycira

    2005-01-01

    This paper introduces Multi-Application Purpose SAR (MAPSAR). A new Synthetic Aperture Radar (SAR) mission for earth observation. MAPSAR is the result of a joint pre-phase A study conducted by INPE and DLR targeting a mission for assessment, management and monitoring of natural resources. The applicability of the sensor system was investigated for cartography, forestry, geology, geomorphology, hydrology, agriculture, disaster management, oceanography, urban studies and security. An L-band SAR, based on INPE's multi-mission platform (MMP), has been chosen as payload of the satellite. The key component of the SAR instrument is the SAR antenna, which is designed as an elliptical parabolic reflector antenna. L-band (high spatial resolution, quad-pol) has been selected for the SAR sensor as optimum frequency accounting for the majority of Brazilian and German user requirements. At the moment, the pre-phase A has been concluded and the phase A is planned to start in early 2003.

  6. A Method of Forest Type Classification Using PolInSAR Data

    NASA Astrophysics Data System (ADS)

    Wang, Xinshuang; Chen, Erxue; Li, Zengyuan; Yao, Wangqiang; Li, Wenmei; Li, Xiao

    2013-01-01

    Forest type mapping is of great significance for regional forest carbon estimation as forest types distribution information is always the critical prior input information to forest carbon stock mapping model using remote sensing. Polarimetric interferometric synthetic aperture radar (Pol-InSAR) data acquired by DLR airborne SAR system (ESAR) in the Traunstein test site in Germany was used to study forest type classification method in this paper. A new unsupervised PolInSAR classification method based on coherent optimization R matrix was proposed to distinguish coniferous forest, deciduous forest and other land cover types. It not only considers the full polarimetric information of single Polarimetric SAR (PolSAR) data set but also the coherent information of a pair of PolSAR data. The results show that the classification algorithm proposed in this paper is the best method with higher accuracy comparing with the classical method based on T6 matrix.

  7. 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.

  8. 3-D SAR image formation from sparse aperture data using 3-D target grids

    NASA Astrophysics Data System (ADS)

    Bhalla, Rajan; Li, Junfei; Ling, Hao

    2005-05-01

    The performance of ATR systems can potentially be improved by using three-dimensional (3-D) SAR images instead of the traditional two-dimensional SAR images or one-dimensional range profiles. 3-D SAR image formation of targets from radar backscattered data collected on wide angle, sparse apertures has been identified by AFRL as fundamental to building an object detection and recognition capability. A set of data has been released as a challenge problem. This paper describes a technique based on the concept of 3-D target grids aimed at the formation of 3-D SAR images of targets from sparse aperture data. The 3-D target grids capture the 3-D spatial and angular scattering properties of the target and serve as matched filters for SAR formation. The results of 3-D SAR formation using the backhoe public release data are presented.

  9. Split-Band Interferometric SAR Processing Using TanDEM-X Data

    NASA Astrophysics Data System (ADS)

    De Rauw, Dominique; Kervyn, Francois; d'Oreye, Nicolas; Smets, Benoit; Albino, Fabien; Barbier, Christian

    2015-05-01

    Most recent SAR sensors use wide band signals to achieve metric range resolution. One can also take advantage of wide band to split it into sub-bands and generate several lower-resolution images, centered on slightly different frequencies, from a single acquisition. This process, named Multi Chromatic Analysis (MCA) corresponds to performing a spectral analysis of SAR images. Split-Band SAR interferometry (SBInSAR) is based on spectral analysis performed on each image of an InSAR pair, yielding a stack of sub-band interferograms. Scatterers keeping a coherent behaviour in each sub-band interferogram show a phase that varies linearly with the carrier frequency, the slope being proportional to the absolute optical path difference. This potentially solves the problems of phase unwrapping on a pixel-per-pixel basis. In this paper, we present an SBInSAR processor and its application using TanDEM-X data over the Nyiragongo volcano.

  10. Observations of Typhoon Eye Using SAR and IR Sensors

    NASA Astrophysics Data System (ADS)

    Liu, Anthony K.; He, Shuangyan; Pan, Yufang; Yang, Jingsong

    2014-11-01

    In this review, recent studies on the observations of typhoon eyes by images acquired by multiple sensors, including synthetic aperture radar (SAR), and infrared (IR) radiometer, are first summarized. Large horizontal distances between typhoon eyes on the ocean surface by SAR and those on the cloud top by IR sensors have been demonstrated; these have previously been ignored but should not be ignored in typhoon forecasts and numerical simulations. Then, based on nine published typhoon cases, the horizontal shifts and vertical tilt angles from the cloud-top typhoon eye locations by IR sensors on board the Feng-Yun 2 (FY-2) and Multi Functional Transport Satellite (MTSAT) to those at sea surface by SAR are further estimated. This shift difference between different sensors raises an issue on project distortion and navigation system errors for FY-2 and MTSAT satellites, which are of concern to both space agencies and data users. Finally, issues for current ongoing study and future research related to typhoon eyes are discussed, including rainband tracking between sensors for local wind speeds.

  11. Retrieval of thin ice thickness from multifrequency polarimetric SAR data

    SciTech Connect

    Kwok, R.; Nghiem, S.V.; Yueh, S.H.; Huynh, D.D.

    1995-03-01

    The authors discuss the observed C- and L-band polarimetric signatures of thin lead ice in one Synthetic Aperture Radar (SAR) image based on the expected ice properties and results from a scattering model. In this article, the authors focus on thin ice with thicknesses in the range of 0-10 cm. The layered scattering model used here allows for the inclusion of surface and volume scattering contributions from a slush layer, an ice layer, and roughness at the interfaces. The sensitivity of the signatures to the model parameters is explored. A highly saline surface skim formed on the top surface during ice growth significantly affects the electromagnetic properties of the medium and helps to explain the magnitude of the copolarized returns at high incidence angles. Based on these model predictions, the authors demonstrate an approach to retrieve the ice thickness from polarimetric SAR observations. The approach includes the training of a neural network with model predictions and using this neural network to estimate the ice thickness distribution using polarimetric observations from SAR data. The results from this ice thickness retrieval process are discussed

  12. Wavelet Analysis of SAR Images for Coastal Monitoring

    NASA Technical Reports Server (NTRS)

    Liu, Antony K.; Wu, Sunny Y.; Tseng, William Y.; Pichel, William G.

    1998-01-01

    The mapping of mesoscale ocean features in the coastal zone is a major potential application for satellite data. The evolution of mesoscale features such as oil slicks, fronts, eddies, and ice edge can be tracked by the wavelet analysis using satellite data from repeating paths. The wavelet transform has been applied to satellite images, such as those from Synthetic Aperture Radar (SAR), Advanced Very High-Resolution Radiometer (AVHRR), and ocean color sensor for feature extraction. In this paper, algorithms and techniques for automated detection and tracking of mesoscale features from satellite SAR imagery employing wavelet analysis have been developed. Case studies on two major coastal oil spills have been investigated using wavelet analysis for tracking along the coast of Uruguay (February 1997), and near Point Barrow, Alaska (November 1997). Comparison of SAR images with SeaWiFS (Sea-viewing Wide Field-of-view Sensor) data for coccolithophore bloom in the East Bering Sea during the fall of 1997 shows a good match on bloom boundary. This paper demonstrates that this technique is a useful and promising tool for monitoring of coastal waters.

  13. Coevolving feature extraction agents for target recognition in SAR images

    NASA Astrophysics Data System (ADS)

    Bhanu, Bir; Krawiec, Krzysztof

    2003-09-01

    This paper describes a novel evolutionary method for automatic induction of target recognition procedures from examples. The learning process starts with training data containing SAR images with labeled targets and consists in coevolving the population of feature extraction agents that cooperate to build an appropriate representation of the input image. Features extracted by a team of cooperating agents are used to induce a machine learning classifier that is responsible for making the final decision of recognizing a target in a SAR image. Each agent (individual) contains feature extraction procedure encoded according to the principles of linear genetic programming (LGP). Like 'plain' genetic programming, in LGP an agent's genome encodes a program that is executed and tested on the set of training images during the fitness calculation. The program is a sequence of calls to the library of parameterized operations, including, but not limited to, global and local image processing operations, elementary feature extraction, and logic and arithmetic operations. Particular calls operate on working variables that enable the program to store intermediate results, and therefore design complex features. This paper contains detailed description of the learning and recognition methodology outlined here. In experimental part, we report and analyze the results obtained when testing the proposed approach for SAR target recognition using MSTAR database.

  14. SAR wind retrieval: from Singlecore to Multicore and GPU computing

    NASA Astrophysics Data System (ADS)

    Myasoedov, Alexander; Monzikova, Anna

    The large spatial coverage and high resolution of spaceborne synthetic aperture radars (SAR) offers a unique opportunity to derive mesoscale wind fields over the ocean surface, providing high resolution wind fields near the shore. On the other hand, due to the large size of SAR images their processing might be a headache when dealing with operational tasks or doing long-period statistical analysis. Algorithms for satellite image processing often offer many possibilities for parallelism (e.g., pixel-by-pixel processing) which makes them good candidates for execution on high-performance parallel computing hardware such as Multicore CPUs and modern graphic processing units (GPUs). In this study we implement different SAR wind speed retrieval algorithms (e.g. CMOD4, CMOD5) for Singlecore and Multicore systems, including GPUs. For this purpose both serial and parallelized versions of CMOD algorithms were written in Matlab, Python, CPython and PyOpenCL. We apply these algorithms to an Envisat ASAR image, compare the results received with different versions of the algorithms executed on both Intel CPU and a Tesla GPU. As a result of our experiments we not only show the up to 400 times speedup of GPU comparing to CPU but also try to give some advises on how much time we have spent and efforts were made for writing the same algorithm using different programming languages. We hope that our experience will help other scientist to achieve all the goodness from the GPU/Multicore computing.

  15. Adaptive SAR ATR problem set (AdaptSAPS)

    NASA Astrophysics Data System (ADS)

    Wise, Angela R.; Fitzgerald, Donna; Ross, Timothy D.

    2004-09-01

    A strong and growing interest in systems that adapt to changing circumstances was evident in panel discussions at the "Algorithms for SAR Imagery" Conference of the AeroSense Symposium in April 2003, with DARPA, Air Force, industry and academia participation. As a result, Conference Co-Chair Mr. Ed Zelnio suggested producing a dynamic model to create problem sets suitable for adaptive system research and development. Such a problem set provides a framework for the overall problem, including organization of operating conditions, performance measures and specific test cases. It is hoped that this AdaptSAPS framework will help provide the community with a more concrete base for discussing adaptation in SAR imagery exploitation. AdaptSAPS Version 1.0 was produced by the AFRL COMPASE and SDMS organizations and posted on 5 August 2003. AdaptSAPS consists of over a dozen MatLab programs that allow the user to create "missions" with SAR data of varying complexities and then present that test data one image at a time, first as unexploited imagery and then later with the exploitation results that an ATR could use for adaptation in an operational environment. AdaptSAPS keeps track of performance results and reports performance measures. This paper describes AdaptSAPS - its application process and possible improvements as a problem set.

  16. The Compound and Homologous Eruptions from the SAR 11429

    NASA Astrophysics Data System (ADS)

    Dhakal, Suman Kumar; Zhang, Jie

    2016-05-01

    Super Active Regions (SARs) are ARs which shows extremely high rate of solar eruptions. NOAA AR 11429 was a SAR which produced 47 C-Class, 15 M-Class and 3 X-Class flares and 8 CMEs during its passage from the front disk of the Sun. This SAR had anti-Hale and delta-spot magnetic configuration and many sub-regions of magnetic flux emergence. With the aid of multi-wavelength observations of the Solar Dynamics Observatory (SDO), the Solar Terrestrial Relations Observatory (STEREO) and nonlinear force-free model for the magnetic field in the solar corona, we found the existence of many magnetic flux structures (flux bundles) in the corona of the AR. The energy released by these co-existing flux bundles within short time, resulted in compound erutpions from the AR on March 9 and 10, 2012. In the period of 38 hours, after the CME eruption on March 9, the continuous shearing and cancellation and new magnetic flux emergence resulted in another CME on March 10. Both of the events showed the compound nature and the similarity of the foot-points and EUV dimming made these eruptions homologous.

  17. Multifrequency OFDM SAR in Presence of Deception Jamming

    NASA Astrophysics Data System (ADS)

    Schuerger, Jonathan; Garmatyuk, Dmitriy

    2010-12-01

    Orthogonal frequency division multiplexing (OFDM) is considered in this paper from the perspective of usage in imaging radar scenarios with deception jamming. OFDM radar signals are inherently multifrequency waveforms, composed of a number of subbands which are orthogonal to each other. While being employed extensively in communications, OFDM has not found comparatively wide use in radar, and, particularly, in synthetic aperture radar (SAR) applications. In this paper, we aim to show the advantages of OFDM-coded radar signals with random subband composition when used in deception jamming scenarios. Two approaches to create a radar signal by the jammer are considered: instantaneous frequency (IF) estimator and digital-RF-memory- (DRFM-) based reproducer. In both cases, the jammer aims to create a copy of a valid target image via resending the radar signal at prescribed time intervals. Jammer signals are derived and used in SAR simulations with three types of signal models: OFDM, linear frequency modulated (LFM), and frequency-hopped (FH). Presented results include simulated peak side lobe (PSL) and peak cross-correlation values for random OFDM signals, as well as simulated SAR imagery with IF and DRFM jammers'-induced false targets.

  18. Topographic slope from the SAR interferometric phase gradient

    NASA Technical Reports Server (NTRS)

    Werner, Charles L.; Rosen, Paul A.

    1993-01-01

    A new algorithm for the direct calculation of topographic slope maps from synthetic aperture radar (SAR) interferograms is presented. The algorithm derives slope maps without first requiring the creation of a digital elevational model (DEM) from the interferogram, thus obviating the need for high SNR in the interferogram and altitude calibration points for the scene. SAR data useful for interferometry has been collected by the Active Microwave Imager on board the ERS-1 satellite, when it was in a short period repeat orbit. Two passes of the radar sensor form a cross-track interferometric baseline. For a point target at some position (x,y,h), the interferometric phase difference phi is proportional to the difference in path lengths for the two sensor positions to the scatterer. Given the phase difference as measured in the complex interferogram and an accurate baseline geometry, the position of the scatterer, most significantly the height h, can be determined through triangulation. The interferometric phase measurement however is known only modulo 2-pi, and hence it is necessary to determine the correct multiple of 2-pi to add to the phase at each point to obtain an estimate of the actual phase with respect to an absolute datum. This phase unwrapping process is required for creating DEM's, and is difficult or impossible for regions of low SNR or SAR image layover. The new algorithm described here derives slope maps without requiring phase unwrapping.

  19. Efficient sliding spotlight SAR raw signal simulation of extended scenes

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Huang, Pingping; Deng, Yunkai

    2011-12-01

    Sliding spotlight mode is a novel synthetic aperture radar (SAR) imaging scheme with an achieved azimuth resolution better than stripmap mode and ground coverage larger than spotlight configuration. However, its raw signal simulation of extended scenes may not be efficiently implemented in the two-dimensional (2D) Fourier transformed domain. This article presents a novel sliding spotlight raw signal simulation approach from the wide-beam SAR imaging modes. This approach can generate sliding spotlight raw signal not only from raw data evaluated by the simulators, but also from real data in the stripmap/spotlight mode. In order to obtain the desired raw data from conventional stripmap/spotlight mode, the azimuth time-varying filtering, which is implemented by de-rotation and low-pass filtering, is adopted. As raw signal of extended scenes in the stripmap/spotlight mode can efficiently be evaluated in the 2D Fourier domain, the proposed approach provides an efficient sliding spotlight SAR simulator of extended scenes. Simulation results validate this efficient simulator.

  20. InSAR and Numeric Modeling for Land Subsidence

    NASA Astrophysics Data System (ADS)

    Wulamu, A.; Grzovic, M.

    2015-12-01

    Monitoring land subsidence due to coal mining is a function of several controlling factors, including: depth of the mine, stratigraphy, presence or absence of faults, thickness of mineral seam, mining method used, and hydrogeological conditions. Numerical modeling, e.g., finite element modeling (FEM), provides a comprehensive tool to simulate three-dimensional deformation at specific locations. The basis of the FEM is the representation of a body or a structure by an assemblage of subdivisions called finite elements, which requires the availability of site specific environmental and physical characteristics. The lack of availability of the necessary data leads to large uncertainties in subsidence estimates. With the use of InSAR, many of the needed controlling parameters for improving mine subsidence rate estimates can be identified. Coupling InSAR with FEM can further improve subsidence rate estimates through additional analysis yielding information on the relative importance of various controlling parameters contributing to the mine subsidence, the key mechanisms of failure associated with these parameters, and the surface expressions of these processes. In this contribution, we show that utilizing InSAR and FEM leads to an overall enhanced understanding of mine behavior, including the physical mechanisms that lead to mine subsidence through understanding the rheological behavior of the material over the mine in response to wide range of physical and environmental conditions.