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1

Sorting Radar Emitter Signal Based on Wpt6 and Cr1  

Microsoft Academic Search

Sorting rate of common method is not high and it is sensitive to the signal noise ratio (SNR), in order to solve these problems, a novel sorting algorithm for radar emitter is proposed. The Wpt6 and Cr1 is extracted firstly and used as the sorting basis when the unknown radar emitter signal is received, then the radar emitter sorting is

Yang Zhi-xiang; Zhu Yuan-qing; Li Xiao-ning; Su Wei

2009-01-01

2

Intra-pulse Modulation Recognition of Advanced Radar Emitter Signals Using Intelligent Recognition Method  

Microsoft Academic Search

A new method is proposed to solve the difficult problem of advanced radar emitter signal (RES) recognition. Different from\\u000a traditional five-parameter method, the method is composed of feature extraction, feature selection using rough set theory\\u000a and combinatorial classifier. Support vector clustering, support vector classification and Mahalanobis distance are integrated\\u000a to design an efficient combinatorial classifier. 155 radar emitter signals with

Gexiang Zhang

2006-01-01

3

Hybrid Radar Emitter Recognition Based on Rough k-Means Classifier and Relevance Vector Machine  

PubMed Central

Due to the increasing complexity of electromagnetic signals, there exists a significant challenge for recognizing radar emitter signals. In this paper, a hybrid recognition approach is presented that classifies radar emitter signals by exploiting the different separability of samples. The proposed approach comprises two steps, namely the primary signal recognition and the advanced signal recognition. In the former step, a novel rough k-means classifier, which comprises three regions, i.e., certain area, rough area and uncertain area, is proposed to cluster the samples of radar emitter signals. In the latter step, the samples within the rough boundary are used to train the relevance vector machine (RVM). Then RVM is used to recognize the samples in the uncertain area; therefore, the classification accuracy is improved. Simulation results show that, for recognizing radar emitter signals, the proposed hybrid recognition approach is more accurate, and presents lower computational complexity than traditional approaches. PMID:23344380

Yang, Zhutian; Wu, Zhilu; Yin, Zhendong; Quan, Taifan; Sun, Hongjian

2013-01-01

4

Electronic intelligence: The interception of radar signals  

NASA Astrophysics Data System (ADS)

Electronic intelligence (Elint) has its basis in the information extracted through analyses of signals transmitted by enemy radar systems and other noncommunications transmitters. This entails the process of signal interception, characterization, and recorded preservation to which attention is presently given. The accumulation of radar signal data in peacetime has grown with the development of modern weapons, many of which incorporate radar target detection and tracking. The present discussions range over the role of radar interception in electronic warfare, the effect of Low Probability of Intercept radar systems, Elint antennas and direction finders, emitter location, the characteristics of crystal, superheterodyne and instantaneous frequency measurement receivers, and such other Elint receivers as the channelized, acoustooptic, and microscan types.

Wiley, R. G.

5

Knowledge-based signal processing for radar ESM systems  

NASA Astrophysics Data System (ADS)

Radar electronic support measures (ESM) systems perform the functions of threat detection and area surveillance to determine the identity and bearing of surrounding radar emitters. Automatic ESM systems incorporate a passive receiver to measure the parameters of detected radar pulses and an automatic processor to rapidly sort pulses and identify the emitters. Current processors use algorithmic processing methods which are inflexible and do not fully utilize available sources of a priori information. The paper discusses the role of knowledge-based processing methods and how they may be applied to the key ESM signal-processing functions of deinterleaving, merge and emitter identification. ESM processors are required to sort input pulse data streams exceeding one million pulses per second and minimize the reporting latency of new emitters. The paper further discusses the requirements to achieve real-time operation of knowledge-based ESM processing techniques.

Roe, J.; Cussons, S.; Feltham, A.

1990-10-01

6

Interception of LPI radar signals  

NASA Astrophysics Data System (ADS)

Most current radars are designed to transmit short duration pulses with relatively high peak power. These radars can be detected easily by the use of relatively modest EW intercept receivers. Three radar functions (search, anti-ship missile (ASM) seeker, and navigation) are examined to evaluate the effectiveness of potential low probability of intercept (LPI) techniques, such as waveform coding, antenna profile control, and power management that a radar may employ against current Electronic Warfare (EW) receivers. The general conclusion is that it is possible to design a LPI radar which is effective against current intercept EW receivers. LPI operation is most easily achieved at close ranges and against a target with a large radar cross section. The general system sensitivity requirement for the detection of current and projected LPI radars is found to be on the order of -100 dBmi which cannot be met by current EW receivers. Finally, three potential LPI receiver architectures, using channelized, superhet, and acousto-optic receivers with narrow RF and video bandwidths are discussed. They have shown some potential in terms of providing the sensitivity and capability in an environment where both conventional and LPI signals are present.

Lee, Jim P.

1991-11-01

7

SHARAD radar signal processing technique  

Microsoft Academic Search

SHARAD (SHAllow RADar) is the sub-surface sounding radar provided by the Italian Space Agency (ASI) as a facility instrument to NASA's 2005 Mars Reconnaissance Orbiter (MRO). SHARAD has been launched on August '05 and has started its nominal observation phase since November '06. Primary objective of its investigation is to map, in selected regions, dielectric interfaces to depths of up

G. Alberti; S. Dinardo; S. Mattei; C. Papa; M. R. Santovito

2007-01-01

8

Optical signal processing in Radar systems  

Microsoft Academic Search

Opto-electronic components and their performances are well suited to be integrated in radar systems. In this paper, two optical architectures illustrate functions that are specific to optical processing of microwave signals, i.e., time-delay-based processing and arbitrary waveform generation of large frequency bandwidth signals.

Sylvie Tonda-Goldstein; Daniel Dolfi; Aymeric Monsterleet; Stéphane Formont; Jean Chazelas; Jean-Pierre Huignard

2006-01-01

9

Packet radar spectrum recovery for physiological signals.  

PubMed

Packet Doppler radar is investigated for extracting physiological signals. System on Chip is employed as a signal source in packet mode, and it transmits signals intermittently at 2.405 GHz to save power. Reflected signals are demodulated directly by spectral analysis of received pulses in the baseband. Spectral subtraction, using data from an empty room, is applied to extract the periodic movement. It was experimentally demonstrated that frequency of the periodic motion can be accurately extracted using this technique. Proposed approach reduces the computation complexity of the signal processing part effectively. PMID:24110048

Yavari, Ehsan; Padasdao, Bryson; Lubecke, Victor; Boric-Lubecke, Olga

2013-01-01

10

Stepped-frequency radar signal processing  

NASA Astrophysics Data System (ADS)

Stepped-frequency radar is a prominent example of the class of continuous-wave radar systems. Since raw data are recorded in frequency-domain direct investigations referring to the frequency content can be done on the raw data. However, a transformation of these data is required in order to obtain a time-domain representation of the targets illuminated by the radar. In this paper we present different ways of arranging the raw data which then are processed by means of the inverse fast Fourier transform. On the basis of the time-domain result we discuss strengths and weaknesses of each of these data structures. Furthermore, we investigate the influence of phase noise on the time-domain signal by means of an appropriate model implemented in our simulation tool. We also demonstrate the effects of commonly known techniques of digital signal processing, such as windowing and zero-padding of frequency-domain data. Finally we present less commonly known methods, such as the processing gain of the (inverse) fast Fourier transform by means of which the signal to noise ratio of the time-domain signal can be increased.

Seyfried, Daniel; Schoebel, Joerg

2015-01-01

11

28. Perimeter acquisition radar building room #302, signal process and ...  

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

28. Perimeter acquisition radar building room #302, signal process and analog receiver room - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

12

Radar transponder apparatus and signal processing technique  

SciTech Connect

An active, phase-coded, time-grating transponder and a synthetic-aperture radar (SAR) and signal processor means, in combination, allow the recognition and location of the transponder (tag) in the SAR image and allow communication of information messages from the transponder to the SAR. The SAR is an illuminating radar having special processing modifications in an image-formation processor to receive an echo from a remote transponder, after the transponder receives and retransmits the SAR illuminations, and to enhance tile transponder`s echo relative to surrounding ground clutter by recognizing special transponder modulations from phase-shifted from the transponder retransmissions. The remote radio-frequency tag also transmits information to the SAR through a single antenna that also serves to receive the SAR illuminations. Unique tag-modulation and SAR signal processing techniques, in combination, allow the detection and precise geographical location of the tag, through the reduction of interfering signals from ground clutter, and allow communication of environmental and status information from said tag to be communicated to said SAR.

Axline, R.M. Jr.; Sloan, G.R.; Spalding, R.E.

1994-12-31

13

Radar transponder apparatus and signal processing technique  

DOEpatents

An active, phase-coded, time-grating transponder and a synthetic-aperture radar (SAR) and signal processor means, in combination, allow the recognition and location of the transponder (tag) in the SAR image and allow communication of information messages from the transponder to the SAR. The SAR is an illuminating radar having special processing modifications in an image-formation processor to receive an echo from a remote transponder, after the transponder receives and retransmits the SAR illuminations, and to enhance the transponder`s echo relative to surrounding ground clutter by recognizing special transponder modulations from phase-shifted from the transponder retransmissions. The remote radio-frequency tag also transmits information to the SAR through a single antenna that also serves to receive the SAR illuminations. Unique tag-modulation and SAR signal processing techniques, in combination, allow the detection and precise geographical location of the tag through the reduction of interfering signals from ground clutter, and allow communication of environmental and status information from said tag to be communicated to said SAR. 4 figs.

Axline, R.M. Jr.; Sloan, G.R.; Spalding, R.E.

1996-01-23

14

Radar transponder apparatus and signal processing technique  

DOEpatents

An active, phase-coded, time-grating transponder and a synthetic-aperture radar (SAR) and signal processor means, in combination, allow the recognition and location of the transponder (tag) in the SAR image and allow communication of information messages from the transponder to the SAR. The SAR is an illuminating radar having special processing modifications in an image-formation processor to receive an echo from a remote transponder, after the transponder receives and retransmits the SAR illuminations, and to enhance the transponder's echo relative to surrounding ground clutter by recognizing special transponder modulations from phase-shifted from the transponder retransmissions. The remote radio-frequency tag also transmits information to the SAR through a single antenna that also serves to receive the SAR illuminations. Unique tag-modulation and SAR signal processing techniques, in combination, allow the detection and precise geographical location of the tag through the reduction of interfering signals from ground clutter, and allow communication of environmental and status information from said tag to be communicated to said SAR.

Axline, Jr., Robert M. (Albuquerque, NM); Sloan, George R. (Albuquerque, NM); Spalding, Richard E. (Albuquerque, NM)

1996-01-01

15

Signal processing techniques for stepped frequency ultra-wideband radar  

NASA Astrophysics Data System (ADS)

The U.S. Army Research Laboratory (ARL) has developed the impulse-based, ground vehicle-based, forward-looking ultra-wideband (UWB), synthetic aperture radar (SAR) to detect concealed targets. Although the impulse-based architecture offers its own advantages, one of the important challenges is that when using this architecture it is very difficult to transmit a radar signal with an arbitrary bandwidth and shape. This feature is crucial for the radar to be compliant with the local frequency authority. In addition, being able to transmit signals with an arbitrary spectral shape is an important step in creating the next generation of smart (cognitive) radars. Therefore, we have designed a next-generation prototype radar to take advantage of the stepped frequency architecture. The design and building of the radar hardware is underway. In this paper, we study the radar transmit and acquisition scheme; the trade-offs between SAR image performance and various key radar parameters; and data reconstruction techniques for radar signals with an arbitrary spectrum. This study demonstrates performance, provides some guidelines for the radar design, and serves as a foundation for the signal and image processing stage.

Nguyen, Lam

2014-05-01

16

Signal to Noise Analysis of iRadar sensors  

SciTech Connect

This document follows my process of testing; comparing; and contrasting several iRadars signal to noise ratios for both HH and VV polarization. A brief introduction is given explaining the basics of iRadar technology and what data I was collecting. The process section explains the steps I took to collect my data along with any procedures I followed. The analysis section compares and contrasts five different radars and the two different polarizations. The analysis also details the radars viewing limitations and area. Finally, the report delves into the effects of two radars interfering with each other. A conclusion goes over the success and findings of the project.

Fritzke, A; Top, P

2009-09-10

17

Signal processing for airborne bistatic radar   

E-print Network

The major problem encountered by an airborne bistatic radar is the suppression of bistatic clutter. Unlike clutter echoes for a sidelooking airborne monostatic radar, bistatic clutter echoes are range dependent. Using ...

Ong, Kian P

18

Signal processor retrofit for air search radar  

NASA Astrophysics Data System (ADS)

An approach for improving the performance of existing air search radars by retrofitting the signal processor while leaving the RF hardware and digital data processor (DDP) essentially unchanged is proposed. By using improved algorithms and computational accuracy, the 1.7-db reduction in processing losses described by Miller et al. (1990) can be achieved and an additional 3-db improvement in signal-to-clutter noise ratio is provided by doubling the bandwidth. By using a smooth sensitivity time control (STC) function to replace the 6-and 12-db steps, the worst-case 0.6-db loss suffered by the present system is reduced to zero. A 12-db gain in dynamic range can be obtained by replacing the current 12-b A/D converters with 14-b devices. Other improvements mentioned involved the use of multiple moving target indicator (MTI) filters to provide a means of sorting the target detections according to a coarse estimate of the target velocity, and the use of a clutter map and modern thresholding algorithms.

Miller, Chauncey S.

19

From Bursts to Back-Projection: Signal Processing Techniques for Earth and Planetary Observing Radars  

NASA Technical Reports Server (NTRS)

Discusses: (1) JPL Radar Overview and Historical Perspective (2) Signal Processing Needs in Earth and Planetary Radars (3) Examples of Current Systems and techniques (4) Future Perspectives in signal processing for radar missions

Rosen, Paul A.

2012-01-01

20

An overview of synthetic aperture radar signal processing techniques  

Microsoft Academic Search

The principles of synthetic aperture radar and its significance in a military and remote sensing context are reviewed. The signal processing operations required to convert the signal data into an image are described. These operations must accomplish two things: correction of the range migration, both walk and curvature; and compression or focusing of the cross-range portion of the signal. These

M. R. vant

1991-01-01

21

Time-frequency analysis of synthetic aperture radar signals  

SciTech Connect

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

Johnston, B.

1996-08-01

22

Emitter recognition using fuzzy inference system  

Microsoft Academic Search

Emitter recognition is the problem of classifying the radar type, from intercepted radar signals. This capability is crucial for classifying approaching enemy ships and aircrafts. The sensed parameters may vary from their actual or reported values because of man-made variations in the form of agility or staggering. Another cause of variation could be dispersion because of atmospheric effects and equipment

S. A. Hassan; A. I. Bhatti; A. Latif

2005-01-01

23

Integration of radio-frequency transmission and radar in general software for multimodal battlefield signal modeling  

NASA Astrophysics Data System (ADS)

The Environmental Awareness for Sensor and Emitter Employment (EASEE) software, being developed by the U. S. Army Engineer Research and Development Center (ERDC), provides a general platform for predicting sensor performance and optimizing sensor selection and placement in complex terrain and weather conditions. It incorporates an extensive library of target signatures, signal propagation models, and sensor systems. A flexible object-oriented design supports efficient integration and simulation of diverse signal modalities. This paper describes the integration of modeling capabilities for radio-frequency (RF) transmission and radar systems from the U. S. Navy Electromagnetic Propagation Integrated Resource Environment (EMPIRE), which contains nearly twenty different realistic RF propagation models. The integration utilizes an XML-based interface between EASEE and EMPIRE to set inputs for and run propagation models. To accommodate radars, fundamental improvements to the EASEE software architecture were made to support active-sensing scenarios with forward and backward propagation of the RF signals between the radar and target. Models for reflecting targets were defined to apply a target-specific, directionally dependent reflection coefficient (i.e., scattering cross section) to the incident wavefields.

Yamamoto, Kenneth K.; Reznicek, Nathan J.; Wilson, D. Keith

2013-05-01

24

Automatic signal processing of front monitor radar for tunneling machines  

SciTech Connect

It is planned to install a front monitoring impulse radar on the surface of the rotating drill of tunneling machines in order to detect obstacles such as casing pipes of vertical borings. The conventional aperture synthesis technique can no more be applied to such cases because the radar image of a pipe dies not constituent a hyperbola as is the case for linear scanning radars. The authors have developed a special purpose signal processing algorithm with the aid of the discrete model fitting method, which can be used for any pattern of scanning. The details of the algorithm are presented together with the results of numerical simulations and test site experiments.

Sato, Toru [Kyoto Univ. (Japan). Dept. of Electronics and Communication] [Kyoto Univ. (Japan). Dept. of Electronics and Communication; Takeda, Kenya [NTT Co. Ltd., Chiba (Japan)] [NTT Co. Ltd., Chiba (Japan); Nagamatsu, Takashi [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan)] [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan); Wakayama, Toshio [Mitsubishi Electric Corp., Kamakura, Kanagawa (Japan)] [Mitsubishi Electric Corp., Kamakura, Kanagawa (Japan); Kimura, Iwane [Osaka Inst. of Tech., Hirakata, Osaka (Japan)] [Osaka Inst. of Tech., Hirakata, Osaka (Japan); Shinbo, Tetsuya [Komatsu Co. Ltd., Kanagawa (Japan)] [Komatsu Co. Ltd., Kanagawa (Japan)

1997-03-01

25

Naval Research Laboratory flex processor for radar signal processing  

NASA Astrophysics Data System (ADS)

This paper describes a programmable radar signal processor architecture developed at the Naval Research Laboratory (NRL). The design incorporates T.I. TMS320C30 programmable digital signal processor devices, Xilinx programmable gate arrays, TRW FFT devices, and a parallel array of Inmos Transputer microprocessors. The architecture is extremely flexible and is applicable to a wide variety of applications.

Alter, James J.; Evins, James B.; Letellier, J. P.

1991-12-01

26

Estimating soil electric properties from monostatic ground-penetrating radar signal inversion in the frequency domain  

NASA Astrophysics Data System (ADS)

A new integrated approach for identifying the shallow subsurface electric properties from ground-penetrating radar (GPR) signal is proposed. It is based on an ultrawide band (UWB) stepped frequency continuous wave (SFCW) radar combined with a dielectric filled transverse electric and magnetic (TEM) horn antenna to be used off the ground in monostatic mode; that is, a single antenna is used as emitter and receiver. This radar configuration is appropriate for subsurface mapping and allows for an efficient and more realistic modeling of the radar-antenna-subsurface system. Forward modeling is based on linear system response functions and on the exact solution of the three-dimensional Maxwell equations for wave propagation in a horizontally multilayered medium representing the subsurface. Subsurface electric properties, i.e., dielectric permittivity and electric conductivity, are estimated by model inversion using the global multilevel coordinate search optimization algorithm combined sequentially with the local Nelder-Mead simplex algorithm (GMCS-NMS). Inversion of synthetic data and analysis of the corresponding response surfaces proved the uniqueness of the inverse solution. Laboratory experiments on a tank filled with a homogeneous sand subject to different water content levels further demonstrated the stability and accuracy of the solution toward measurement and modeling errors, particularly those associated with the dielectric permittivity. Inversion for the electric conductivity led to less satisfactory results. This was mainly attributed to the characterization of the frequency response of the antenna and to the high frequency dependence of the electric conductivity.

Lambot, S.; Slob, E. C.; van den Bosch, I.; Stockbroeckx, B.; Scheers, B.; Vanclooster, M.

2004-04-01

27

Optimum signal format for pulse compression radar  

Microsoft Academic Search

The design of a pulse compression radar is discussed in terms of a receiver with normalized output defined by an ambiguity function. An optimum narrowing of the ambiguity function along the time axis yields enhanced range accuracy and resolution. Optimal autocorrelation functions having the shortest duration for the allowable sidelobe level are found using Dolph-Chebyshev polynomials, leading to optimum sidelobe

M. C. Chandra Mouly; R. C. Pande

1981-01-01

28

Windshear detection radar signal processing studies  

NASA Technical Reports Server (NTRS)

This final report briefly summarizes research work at Clemson in the Radar Systems Laboratory under the NASA Langley Research Grant NAG-1-928 in support of the Antenna and Microwave Branch, Guidance and Control Division, program to develop airborne sensor technology for the detection of low altitude windshear. A bibliography of all publications generated by Clemson personnel is included. An appendix provides abstracts of all publications.

Baxa, Ernest G., Jr.

1993-01-01

29

Location plan for Signal Corps Radar (S.C.R.) 296 Station 5, ...  

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

Location plan for Signal Corps Radar (S.C.R.) 296 Station 5, October 8, 1943 - Fort Barry, Signal Corps Radar 296, Station 5, Transmitter Building Foundation, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

30

Radar antenna pointing for optimized signal to noise ratio.  

SciTech Connect

The Signal-to-Noise Ratio (SNR) of a radar echo signal will vary across a range swath, due to spherical wavefront spreading, atmospheric attenuation, and antenna beam illumination. The antenna beam illumination will depend on antenna pointing. Calculations of geometry are complicated by the curved earth, and atmospheric refraction. This report investigates optimizing antenna pointing to maximize the minimum SNR across the range swath.

Doerry, Armin Walter; Marquette, Brandeis [General Atomics Aeronautical Systems, Inc., San Diego, CA

2013-01-01

31

Detail view of southeast corner of Signal Corps Radar (S.C.R.) ...  

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

Detail view of southeast corner of Signal Corps Radar (S.C.R.) 296 Station 5 Transmitter Building foundation, showing Signal Corps Radar (S.C.R.) 296 Station 5 Tower concrete pier in background, camera facing north - Fort Barry, Signal Corps Radar 296, Station 5, Transmitter Building Foundation, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

32

Comparison between surface impulse ground penetrating radar signals and ultrasonic time-of-flight diffraction signals  

Microsoft Academic Search

Surface impulse ground-penetrating radar (GPR) and ultrasonic time-of-flight diffraction (TOFD) are recent innovations in the respective geophysical remote sensing and non-destructive testing industries. Both techniques have proved highly versatile and valuable applications. This paper provides a brief description of the time-of-flight diffraction (TOFD) signals and the surface impulse ground penetrating radar (GPR) signals. The similarities between the two techniques are

O. Zahran; S. Shihab; W. Al-Nuaimy

2002-01-01

33

Subband-domain signal processing for radar array systems  

NASA Astrophysics Data System (ADS)

Subband-domain algorithms provide an attractive technique for wideband radar array processing. The subband-domain approach decomposes a received wideband signal into a set of narrowband signals. While the number of processing threads in the system increases, the narrowband signals within each subband can be sampled at a correspondingly slower rate. Therefore, the data rate at the input is similar to that at the output of the subband processor. There are several advantages to the subbanding method. It can simplify typical radar algorithms such as adaptive beamforming and equalization by the virtue of reducing subband signal bandwidth, thereby potentially reducing the computational complexity over an equivalent tapped-delay line approach. It also allows for a greater parallelization of the processing task, hence enabling the use of slower and less power consuming hardware. In order to evaluate the validity of the subbanding approach, it is compared with conventional processing methods. This paper focuses on adaptive beamforming and pulse compression performance for a wideband radar system. The performance of an adaptive beamformer is given for a polyphase filter based subband approach and is measured against narrowband processing. SINR loss curves and beampatterns for a subband system are presented. Design criteria for subband polyphase filter processing that minimizes signal distortion are provided and the distortion is characterized. Finally subband- domain pulse compression is demonstrated and compared with the conventional approach.

Rabinkin, Daniel V.; Pulsone, Nicholas B.

1999-11-01

34

Digital Radar-Signal Processors Implemented in FPGAs  

NASA Technical Reports Server (NTRS)

High-performance digital electronic circuits for onboard processing of return signals in an airborne precipitation- measuring radar system have been implemented in commercially available field-programmable gate arrays (FPGAs). Previously, it was standard practice to downlink the radar-return data to a ground station for postprocessing a costly practice that prevents the nearly-real-time use of the data for automated targeting. In principle, the onboard processing could be performed by a system of about 20 personal- computer-type microprocessors; relative to such a system, the present FPGA-based processor is much smaller and consumes much less power. Alternatively, the onboard processing could be performed by an application-specific integrated circuit (ASIC), but in comparison with an ASIC implementation, the present FPGA implementation offers the advantages of (1) greater flexibility for research applications like the present one and (2) lower cost in the small production volumes typical of research applications. The generation and processing of signals in the airborne precipitation measuring radar system in question involves the following especially notable steps: The system utilizes a total of four channels two carrier frequencies and two polarizations at each frequency. The system uses pulse compression: that is, the transmitted pulse is spread out in time and the received echo of the pulse is processed with a matched filter to despread it. The return signal is band-limited and digitally demodulated to a complex baseband signal that, for each pulse, comprises a large number of samples. Each complex pair of samples (denoted a range gate in radar terminology) is associated with a numerical index that corresponds to a specific time offset from the beginning of the radar pulse, so that each such pair represents the energy reflected from a specific range. This energy and the average echo power are computed. The phase of each range bin is compared to the previous echo by complex conjugate multiplication to obtain the mean Doppler shift (and hence the mean and variance of the velocity of precipitation) of the echo at that range.

Berkun, Andrew; Andraka, Ray

2004-01-01

35

Signal based motion compensation for synthetic aperture radar  

SciTech Connect

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

John Kirk

1999-06-07

36

Target Detection in Doppler Radar with PSK Signals  

E-print Network

for automatic detection of moving targets by Doppler radar with continuous transmission of PSP (Phase Shift number of FFT). The Doppler radar is radar with continuous transmission of PSP (Phase Shift Keying is correctly defined. Keywords ­ Radar detection, CFAR processors, Dopller radar I. INTRODUCTION Automatic

Borissova, Daniela

37

Determining weather radar antenna pointing using signals detected from the sun at low antenna elevations  

E-print Network

Determining weather radar antenna pointing using signals detected from the sun at low antenna radiation of the sun for checking of the antenna alignment and of the sensitivity of the receiver chain is a well established method in weather radar maintenance, and radar manufacturers offer sun calibration

Stoffelen, Ad

38

Dependence of radar signal strength on frequency and aspect angle of nonspecular meteor trails  

E-print Network

Dependence of radar signal strength on frequency and aspect angle of nonspecular meteor trails S and 140 km altitude. High-power, large-aperture (HPLA) radars detect nonspecular trails when VHF or UHF is an HPLA radar operating simultaneously at 160 MHz and 422 MHz on the Kwajalein Atoll. First, we

Oppenheim, Meers

39

Optimal sampling and quantization of synthetic aperture radar signals  

NASA Technical Reports Server (NTRS)

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

Wu, C.

1978-01-01

40

Advanced Signal Analysis for Forensic Applications of Ground Penetrating Radar  

SciTech Connect

Ground penetrating radar (GPR) systems have traditionally been used to image subsurface objects. The main focus of this paper is to evaluate an advanced signal analysis technique. Instead of compiling spatial data for the analysis, this technique conducts object recognition procedures based on spectral statistics. The identification feature of an object type is formed from the training vectors by a singular-value decomposition procedure. To illustrate its capability, this procedure is applied to experimental data and compared to the performance of the neural-network approach.

Steven Koppenjan; Matthew Streeton; Hua Lee; Michael Lee; Sashi Ono

2004-06-01

41

Synthetic aperture radar signal processing on the MPP  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

42

Determining human target facing orientation using bistatic radar micro-Doppler signals  

NASA Astrophysics Data System (ADS)

Micro-Doppler radar signals can be used to separate moving human targets from stationary clutter and also to identify and classify human movements. Traditional micro-Doppler radar systems which use a single sensor, monostatic system, suffer from the drawback that only the radial component of the micro-Doppler signal will be observed by the radar operator. This reduces the sensitivity of human activity recognition if the movements are not directly towards or away with respect to the line-of-sight to the radar antenna. In this paper, we propose the use of two bistatic micro-Doppler sensors to overcome this limitation. By using multiple sensors, the orientation of oscillating targets with respect to the radar line-of-sight can be inferred, thereby providing additional information to the radar operator. This approach can be used to infer the facing direction of the human with respect to the radar beam.

Fairchild, Dustin P.; Narayanan, Ram M.

2014-06-01

43

Passive Covert Radars using CP-OFDM signals. A new efficient method to extract targets echoes  

E-print Network

Passive Covert Radars using CP-OFDM signals. A new efficient method to extract targets echoes, France Email: briolle@cpt.univ-mrs.fr Abstract--Passive Coherent Location (PCL) systems use the signal. I. INTRODUCTION A Passive Coherent Location (PCL) system or Passive Covert Radar is an emerging

Paris-Sud XI, Université de

44

View of Signal Corps Radar (S.C.R.) 296 Station 5 Transmitter ...  

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

View of Signal Corps Radar (S.C.R.) 296 Station 5 Transmitter Building foundation, showing Fire Control Stations (Buildings 621 and 622) and concrete stairway (top left) camera facing southwest - Fort Barry, Signal Corps Radar 296, Station 5, Transmitter Building Foundation, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

45

Detail view of northwest side of Signal Corps Radar (S.C.R.) ...  

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

Detail view of northwest side of Signal Corps Radar (S.C.R.) 296 Station 5 Transmitter Building foundation, showing portion of concrete gutter drainage system and asphalt floor tiles, camera facing north - Fort Barry, Signal Corps Radar 296, Station 5, Transmitter Building Foundation, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

46

Graphical derivations of radar, sonar, and communication signals  

NASA Technical Reports Server (NTRS)

The designer of a communication system often has knowledge concerning the changes in distance between transmitter and receiver as a function of time. This information can be exploited to reduce multipath interference via proper signal design. A radar or sonar may also have good a priori information about possible target trajectories. Such knowledge can again be used to reduce the receiver's response to clutter (MTI), to enhance signal-to-noise ratio, or to simplify receiver design. There are also situations in which prior knowledge about trajectories is lacking. The system should then utilize a single-filter pair which is insensitive to the effects induced by relative motion between transmitter, receiver, and reflectors. For waveforms with large time-bandwidth products, such as long pulse trains, it is possible to graphically derive signal formats for both situations (trajectory known and unknown). Although the exact form of the signal is sometimes not specified by the graphical procedure, the problem in such cases is reduced to one which has already been solved, i.e., the generation of an impulse equivalent code.

Altes, R. A.; Titlebaum, E. L.

1975-01-01

47

Non-contact physiological signal detection using continuous wave Doppler radar.  

PubMed

The aim of this work is to show non-contact physiological signal monitoring system based on continuous-wave (CW) Doppler radar, which is becoming highly attractive in the field of health care monitoring of elderly people. Two radar signal processing methods were introduced in this paper: one to extract respiration and heart rates of a single person and the other to separate mixed respiration signals. To verify the validity of the methods, physiological signal is obtained from stationary human subjects using a CW Doppler radar unit. The sensor operating at 24 GHz is located 0.5 meter away from the subject. The simulation results show that the respiration and heart rates are clearly extracted, and the mixed respiration signals are successfully separated. Finally, reference respiration and heart rate signals are measured by an ECG monitor and compared with the results tracked by the CW Doppler radar monitoring system. PMID:24211989

Qiao, Dengyu; He, Tan; Hu, Boping; Li, Ye

2014-01-01

48

Signal-to-Noise Ratio in Doppler Radar System for Heart and Respiratory Rate Measurements  

Microsoft Academic Search

A CMOS Doppler radar sensor has been developed and used to measure motion due to heart and respiration. The quadrature direct-conversion radar transceiver has been fully integrated in 0.25-mum CMOS, the baseband analog signal conditioning has been developed on a printed circuit board, and digital signal processing has been performed in Matlab. The theoretical signal-to-noise ratio (SNR) is derived based

Amy D. Droitcour; Olga Boric-Lubecke; Gregory T. A. Kovacs

2009-01-01

49

Moving target detection via digital time domain correlation of random noise radar signals  

Microsoft Academic Search

Ultra-wideband random noise radar theoretically has a thumbtack ambiguity function, which cannot be realized due to hardware, processing, and environmental limitations. Velocity estimation using traditional Doppler processing is not practicable for ultra-wideband random noise radar because of the large fractional bandwidth. Through analysis, this paper explores moving target detection using digital correlation processing of random noise signals in the time

James R. Lievsay; Geoffrey A. Akers

2011-01-01

50

Comparison of Target Detection Schemes in Doppler Radar with PSK Signals  

E-print Network

in the frequency domain for automatic detection of moving targets by Doppler radar with continuous transmission. INTRODUCTION Automatic detection and classification of ground moving targets in conditions of natural transmission of a PSK signal generated as a long pseudorandom pulse sequence (figure 1). Fig. 1 Radar system

Borissova, Daniela

51

Estimating soil electric properties from monostatic ground-penetrating radar signal inversion in the frequency domain  

Microsoft Academic Search

A new integrated approach for identifying the shallow subsurface electric properties from ground-penetrating radar (GPR) signal is proposed. It is based on an ultrawide band (UWB) stepped frequency continuous wave (SFCW) radar combined with a dielectric filled transverse electric and magnetic (TEM) horn antenna to be used off the ground in monostatic mode; that is, a single antenna is used

S. Lambot; E. C. Slob; I. van den Bosch; B. Stockbroeckx; B. Scheers; M. Vanclooster

2004-01-01

52

Effects of noise, sampling rate and signal sparsity for compressed sensing Synthetic Aperture Radar pulse compression  

Microsoft Academic Search

The traditional radar system needs large bandwidth, and the increasing number of channels brings huge amount of data. These data can easily overflow the memory of the sensor or the bandwidth of the signal which transferred to the ground station. In order to solve this problem, a new method of acquiring Synthetic Aperture Radar (SAR) raw data and compressing pulse

Peng Xiao; Chunsheng Li; Yu Ze

2011-01-01

53

The use of digital RF memories in radar signal processing  

NASA Astrophysics Data System (ADS)

This paper describes the use that may be made of Digital RF Memories in developing and evaluating new radar systems. It outlines the basic DRFM technology showing how a DRFM works and the sort of performance that may be expected. The application of this technology to radar is then discussed showing the advantages that may be obtained through the use of coherent digital IF processing. Finally some experimental DRFM based radar configurations are described illustrating the results that have been achieved and the implications that these might have on future radar systems.

Clark, D. G. D.; Ingram, P. M.

54

Optimal Signal Processing of Frequency-Stepped CW Radar Data  

NASA Technical Reports Server (NTRS)

An optimal signal processing algorithm is derived for estimating the time delay and amplitude of each scatterer reflection using a frequency-stepped CW system. The channel is assumed to be composed of abrupt changes in the reflection coefficient profile. The optimization technique is intended to maximize the target range resolution achievable from any set of frequency-stepped CW radar measurements made in such an environment. The algorithm is composed of an iterative two-step procedure. First, the amplitudes of the echoes are optimized by solving an overdetermined least squares set of equations. Then, a nonlinear objective function is scanned in an organized fashion to find its global minimum. The result is a set of echo strengths and time delay estimates. Although this paper addresses the specific problem of resolving the time delay between the two echoes, the derivation is general in the number of echoes. Performance of the optimization approach is illustrated using measured data obtained from an HP-851O network analyzer. It is demonstrated that the optimization approach offers a significant resolution enhancement over the standard processing approach that employs an IFFT. Degradation in the performance of the algorithm due to suboptimal model order selection and the effects of additive white Gaussion noise are addressed.

Ybarra, Gary A.; Wu, Shawkang M.; Bilbro, Griff L.; Ardalan, Sasan H.; Hearn, Chase P.; Neece, Robert T.

1995-01-01

55

Optimal Signal Processing of Frequency-Stepped CW Radar Data  

NASA Technical Reports Server (NTRS)

An optimal signal processing algorithm is derived for estimating the time delay and amplitude of each scatterer reflection using a frequency-stepped CW system. The channel is assumed to be composed of abrupt changes in the reflection coefficient profile. The optimization technique is intended to maximize the target range resolution achievable from any set of frequency-stepped CW radar measurements made in such an environment. The algorithm is composed of an iterative two-step procedure. First, the amplitudes of the echoes are optimized by solving an overdetermined least squares set of equations. Then, a nonlinear objective function is scanned in an organized fashion to find its global minimum. The result is a set of echo strengths and time delay estimates. Although this paper addresses the specific problem of resolving the time delay between the first two echoes, the derivation is general in the number of echoes. Performance of the optimization approach is illustrated using measured data obtained from an HP-X510 network analyzer. It is demonstrated that the optimization approach offers a significant resolution enhancement over the standard processing approach that employs an IFFT. Degradation in the performance of the algorithm due to suboptimal model order selection and the effects of additive white Gaussion noise are addressed.

Ybarra, Gary A.; Wu, Shawkang M.; Bilbro, Griff L.; Ardalan, Sasan H.; Hearn, Chase P.; Neece, Robert T.

1995-01-01

56

Super-resolution techniques for velocity estimation using UWB random noise radar signals  

NASA Astrophysics Data System (ADS)

The Doppler spread pertaining to the ultrawideband (UWB) radar signals from moving target is directly proportional to the bandwidth of the transmitted signal and the target velocity. Using typical FFT-based methods, the estimation of true velocities pertaining to two targets moving with relatively close velocities within a radar range bin is problematic. In this paper, we extend the Multiple Signal Classification (MUSIC) algorithm to resolve targets moving velocities closer to each other within a given range bin for UWB random noise radar waveforms. Simulated and experimental results are compared for various target velocities using both narrowband (200MHz) and wideband (1GHz) noise radar signals, clearly establishing the unbiased and unambiguous velocity estimations using the MUSIC algorithm.

Dawood, Muhammad; Quraishi, Nafish; Alejos, Ana V.

2011-06-01

57

Distributed position-adaptive UAV radar concepts for building geometries with multiple signal-leakage points  

Microsoft Academic Search

Distributed airborne sensor geometries are considered that are comprised of multiple radar\\/comm transmit and receive nodes. Under this distributed robotic sensor concept, each of these radar transmit\\/receive nodes position-adaptively converge to the vicinity of a signal leakage point. A number of signal leakage point geometries are investigated that conform to geometries for typical building-type structures. The results include a set

Atindra K. Mitra

2006-01-01

58

Signal processing for airborne doppler radar detection of hazardous wind shear as applied to NASA 1991 radar flight experiment data  

NASA Technical Reports Server (NTRS)

Radar data collected during the 1991 NASA flight tests have been selectively analyzed to support research directed at developing both improved as well as new algorithms for detecting hazardous low-altitude windshear. Analysis of aircraft attitude data from several flights indicated that platform stability bandwidths were small compared to the data rate bandwidths which should support an assumption that radar returns can be treated as short time stationary. Various approaches at detection of weather returns in the presence of ground clutter are being investigated. Non-coventional clutter rejection through spectrum mode tracking and classification algorithms is a subject of continuing research. Based upon autoregressive modeling of the radar return time sequence, this approach may offer an alternative to overcome errors in conventional pulse-pair estimates. Adaptive filtering is being evaluated as a means of rejecting clutter with emphasis on low signal-to-clutter ratio situations, particularly in the presence of discrete clutter interference. An analysis of out-of-range clutter returns is included to illustrate effects of ground clutter interference due to range aliasing for aircraft on final approach. Data are presented to indicate how aircraft groundspeed might be corrected from the radar data as well as point to an observed problem of groundspeed estimate bias variation with radar antenna scan angle. A description of how recorded clutter return data are mixed with simulated weather returns is included. This enables the researcher to run controlled experiments to test signal processing algorithms. In the summary research efforts involving improved modelling of radar ground clutter returns and a Bayesian approach at hazard factor estimation are mentioned.

Baxa, Ernest G., Jr.

1992-01-01

59

Radar signal pre-processing to suppress surface bounce and multipath  

DOEpatents

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

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

2013-12-31

60

Theoretical and experimental study of EKB radar ground-scatter signals at nearby frequencies  

NASA Astrophysics Data System (ADS)

SuperDARN radars have wide possibilities for diagnostics of different motions in the ionosphere. The radars allow studying small-, medium- and large-scale irregularities. The radars have good time resolution (about 1 minute for full scan) and wide territory coverage (azimuthal coverage - 50 degrees, maximal range — 3000 km). EKB radar is the first russian radar of SuperDARN kind, installed by ISTP SB RAS near Ekaterinburg. The radar started its operation in December 2012. Mostly SuperDARN radars are used to investigate irregular structure of the ionosphere. In the work we present original approach that allows diagnose regular ionosphere. The approach is based on sounding at three close frequencies and on analysis of ground-scattered signal properties. As theoretical analysis shows the use of three-frequency sounding technique allows one to estimate following characteristics of the model quasiparabolic F-layer in a middle point of path: its critical frequency, the height of its maximum and layer thickness. For this purpose we use known dependence of a minimal group path of signal on radar frequency. The key problem for the described technique is optimizing the frequency step between sounding signals. From the one side, the frequency step should be large enough. This is necessary for the difference in group delays be larger than radar range resolution (15-60km). From the other side, significant variation of frequency leads to a significant movement of path midpoint. This leads to signifficant errors in estimating ionospheric paramters due to theirs horizontal gradients. To solve this problem we perform a simulation of ground-scattered signal at EKB radar in different geophysical conditions. We use IRI-2007 as a model of the ionosphere. We simulate experiment at different levels of solar activity, in different seasons and daytime. By using geometrooptical ray tracing method we calculate a signal minimal group paths for a set of frequencies. According to these data we determine the minimal frequency step that provides difference between group pathes bigger than radar range resolution. Our study shows that for EKB radar the optimal frequency step is about 300kHz. The simulation results was used for scheduling EKB radar for several monthes at one of the channels. The results of processing this data are also presented in the work. Work was done under financial support of II.12.2.3. FSI program.

Kutelev, Konstantin; Berngardt, Oleg; Grkovich, Konstantin; Mikhailov, Nikita

61

Earth curvature and atmospheric refraction effects on radar signal propagation.  

SciTech Connect

The earth isn't flat, and radar beams don't travel straight. This becomes more noticeable as range increases, particularly at shallow depression/grazing angles. This report explores models for characterizing this behavior.

Doerry, Armin Walter

2013-01-01

62

Threat radar system simulations  

NASA Astrophysics Data System (ADS)

The capabilities, requirements, and goals of radar emitter simulators are discussed. Simulators are used to evaluate competing receiver designs, to quantify the performance envelope of a radar system, and to model the characteristics of a transmitted signal waveform. A database of candidate threat systems is developed and, in concert with intelligence data on a given weapons system, permits upgrading simulators to new projected threat capabilities. Four currently available simulation techniques are summarized, noting the usefulness of developing modular software for fast controlled-cost upgrades of simulation capabilities.

Miller, L.

63

IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 55, NO. 8, AUGUST 2007 4151 On Probing Signal Design For MIMO Radar  

E-print Network

of the targets of interest, or more generally to approximate a given transmit beampattern, and also to minimize the cross-correlation of the signals reflected back to the radar by the targets of interest. In this paper the cross-correlation of the signals bounced from various targets of interest--an operation that, once again

Xie, Yao

64

The influence of relief on formation of reflected signals of subsurface sounding radar  

NASA Astrophysics Data System (ADS)

Radar sounding of the surface and near-surface layer of the Moon by the RLK-L low-frequency radar complex from the orbiter module is planned for the Moon-Globe Russian mission. To forecast results of radar experiments, a simulation procedure of the reflection of the RLK-L radar signal by the Moon's surface is designed. The 3D surface model, based on measurement results of the Lunar Orbiter Laser Altimeter (LOLA) of the Lunar Reconnaissance Orbiter mission was used in the calculations. The simulation results showed that the spectrum shape of the reflected signal depends on the relief type in the experimental area. Therefore, when the depth distribution of the permittivity of the geological media is determined, the topographic information should be taken into account.

Smirnov, V. M.; Yushkova, O. V.; Karachevtseva, I. P.; Nadezhdina, I. E.

2014-05-01

65

Passive Covert Radars using CP-OFDM SFN. Reference signal recovery from blind beamforming  

E-print Network

Passive Covert Radars using CP-OFDM SFN. Reference signal recovery from blind beamforming Ghislain: briolle@cpt.univ-mrs.fr Abstract--A passive Coherent Location (PCL) system uses the signal transmitted. Results of real measurements are presented. I. INTRODUCTION A passive Coherent Location (PCL) system

Paris-Sud XI, Université de

66

Digital Signal Generator and Receiver design For S-band Radar  

Microsoft Academic Search

The new generation of radar has to be equipped with a high performance exciters and receivers to cope with the threat in an Electronic Warfare scenario. The threat in a complex environment with interfering signals requires a reliable signal generation with proper frequency agility and efficient gain controls in receiver units. This is quite cumbersome to achieve in analog domain.

L. Prakasam; T. Roy; D. Meena

2007-01-01

67

FPGAs make a radar signal processor on a chip a reality  

Microsoft Academic Search

Radar signal processors heavily tax the capabilities of conventional microprocessor based signal processing systems. Higher performance systems using custom silicon cost too much for the typically small production volumes, and are not flexible enough for research applications. Field programmable gate arrays offer the performance of custom silicon while maintaining the economies and flexibility of the microprocessor based solutions. Recent devices

Ray Andraka; A. Berkun

1999-01-01

68

Generating nonlinear FM chirp radar signals by multiple integrations  

SciTech Connect

A phase component of a nonlinear frequency modulated (NLFM) chirp radar pulse can be produced by performing digital integration operations over a time interval defined by the pulse width. Each digital integration operation includes applying to a respectively corresponding input parameter value a respectively corresponding number of instances of digital integration.

Doerry, Armin W. (Albuquerque, NM)

2011-02-01

69

Clutter signal polarization in bistatic radar: Effect of antenna sidelobe clutter  

NASA Astrophysics Data System (ADS)

Sidelobe contributions to a radar signal's polarization may distort the polarization of clutter originating in the mainbeam. To assure that radar clutter polarization measurements are accurate and that polarization nulling algorithms under consideration would work properly, it is necessary to analyze the contributions of antenna sidelobe clutter to signal polarization. This report considers two bistatic radar configurations over homogeneous terrain. The terrain is represented by the two-scale-of-roughness bistatic scattering model. Two antenna models are used, one a square aperture and the other a simple approximation to a circular aperture with adjustable sidelobe levels. The results for the square aperture show a small change in the signal polarization from the mainbeam-only value when the sidelobes are added in. For the adjustable sidelobe level antenna the sidelobe corruption is small until the uniform sidelobe level reaches -20 dB.

Fallon, Daniel S.; Poirier, J. L.

1994-05-01

70

The dynamic range of radar signal generation in the MSS-2 simulation facility  

NASA Astrophysics Data System (ADS)

The dynamic range of radar signal generation in the MSS-2 affects the types of targets and environments which the MSS-2 facility can simulate. Only the power handling capability of the facility limits the maximum size of large targets; however, assessing the ability of the MSS-2 to produce very small targets is quite difficult and depends on the characteristics of the device under test. This report addresses the issues which limit minimum target size and calculations the dynamic range of the radar signal generation equipment in the MSS-2 given a typical seeker.

Bishop, Chris

1995-03-01

71

Distributed position-adaptive UAV radar concepts for building geometries with multiple signal-leakage points  

NASA Astrophysics Data System (ADS)

Distributed airborne sensor geometries are considered that are comprised of multiple radar/comm transmit and receive nodes. Under this distributed robotic sensor concept, each of these radar transmit/receive nodes position-adaptively converge to the vicinity of a signal leakage point. A number of signal leakage point geometries are investigated that conform to geometries for typical building-type structures. The results include a set of electromagnetic computations that simulate the signal interaction and signal propagation between multiple leakage points. These signals are simulated via the modeling of materials that enclose "building-type" structures with a series of connected dielectric materials. For example, windows, walls, and doors are each modeled separately by a combination of suitable material properties. Signals from objects that are embedded within these "building-type" structures are also simulated via the development and application of appropriate geometrical and materials models. Analysis of the resulting simulated "leakage signals", that penetrate the surfaces of these "building-type" structures and are scattered from embedded objects within the indoor environment back to the simulated sensor-nodes in the outdoor environment, are presented. Interpretations of these results are included from a signal analysis perspective. These results also include approximate preliminary systems-type calculations with regard to this distributed position-adaptive UAV radar system concept. Potential applications are outdoor-to-indoor detection of objects-of-interest that are within a building via implementation of a intelligent multi-static sensor network.

Mitra, Atindra K.

2006-05-01

72

Iterated wavelet transformation and signal discrimination for HRR radar target recognition  

Microsoft Academic Search

This paper explores the use of wavelets to improve the selection of discriminant features in the target recognition problem using High Range Resolution (HRR) radar signals in an air to air scenario. We show that there is statistically no difference among four different wavelet families in extracting discriminatory features. Since similar results can be obtained from any of the four

Dale E. Nelson; Janusz A. Starzyk; D. David Ensley

2003-01-01

73

Martian underground water detection: Thermal model and simulations of radar signal propagation  

Microsoft Academic Search

The thermophysical conditions of ice\\/water existence in the upper Martian crust have been considered in the frame of a multilayer structurally inhomogeneous geological model. The water even at the equatorial site has been shown to exist only at depths below 1 km for any values of the upper layer emissivity and internal flux intensity. The radar signal propagation in the

Oleg B. Shchuko; Daniil V. Kartashov; Giovanni Picardi; Roberto Orosei

2003-01-01

74

Performance of a digital signal processor with impulse noise suppression (meteor radar detection system appl.)  

Microsoft Academic Search

Scanning systems which produce records of electromagnetic input signals are usually subject to random impulse interference which may seriously degrade the records. An impulse noise suppressor employing digital techniques has been developed which has general applicability to such systems and which has been employed with success in a meteor radar installation and a thermal infrared scanning system. The results of

C. S. L. Keay; J. E. Butler; J. A. Kennewell

1976-01-01

75

Optimization of the interperiod processing of signals with clutter rejection in an incoherent radar system  

NASA Astrophysics Data System (ADS)

An energy criterion was used to optimize an algorithm for clutter rejection in an incoherent radar system. Explicit formulas are obtained for the weight vector and the efficiency of the algorithm, and attention is given to the conditions under which these formulas can be applied to signal processing in the postdetector channel.

Kiselev, A. Z.

1981-12-01

76

Squeezing the Local Oscillator Does Not Improve Signal-to-Noise Ratio in Heterodyne Laser Radar  

E-print Network

The signal-to-noise ratio for heterodyne laser radar with a coherent target-return beam and a squeezed local-oscillator beam is lower than that obtained using a coherent local oscillator, regardless of the method employed to combine the beams at the detector.

Mark A. Rubin; Sumanth Kaushik

2007-04-05

77

Wideband signal design for over-the-horizon radar in cochannel interference  

NASA Astrophysics Data System (ADS)

Ship detection in heavy sea clutter is a big challenge for over-the-horizon (OTH) radar. Wideband signal is helpful for improving range resolution and the signal-to-clutter ratio. In this paper, to support OTH radar employing wideband in cochannel interference, we propose environmental sensing-based waveform (ESBW) strategy, by considering transmit waveform design as an active approach and cognitive loop for the time-varying environment. In ESBW strategy, OTH radar monitors the environment in real time, estimates interference characteristics, designs transmit waveform adaptively, and employs traditional signal processing structure to detect targets in the presence of interference. ESBW optimization problem employs the criteria of maximizing the output signal-to-interference-plus-noise ratio (SINR) of matched filter and similarity constraint for reasonable range resolution and sidelobe levels. The analytic solution to this constrained problem is developed, so that ESBW design algorithm's efficiency is guaranteed, with adjustable SINR and autocorrelation function. A simulated scenario with strong interference and colored noise has been introduced. Simulation results demonstrate that OTH radar with ESBW strategy detects the target successfully in the background of cochannel interference.

Luo, Zhongtao; Lu, Kun; Chen, Xuyuan; He, Zishu

2014-12-01

78

Complex, aperiodic random signal modulation on pulse-LFM chirp radar waveform  

NASA Astrophysics Data System (ADS)

In an effort to enhance the security of radar, the plausibility of using a complex, aperiodic random signal to modulate a pulse linear frequency modulation (LFM) or "chirp" radar waveform across both its fast-time and slow-time samples is investigated. A non-conventional threat is considered when illustrating the effectiveness of the proposed waveform as an electronic counter-countermeasure (ECCM). Results are derived using stretch processing and are assessed using the receiver cross-correlation function with a consideration for the unmodulated case as a basis for comparison. A tailored radar ambiguity function is also included in the analysis, and is used to demonstrate how the proposed waveform possesses an ideal characteristic suitable for combating today's electronic warfare (EW) threats while preserving its inherent functionality to detect targets.

Govoni, Mark A.; Li, Hongbin

2010-04-01

79

An update on UHF radar meteor observations and associated signal processing techniques at Arecibo Observatory  

NASA Astrophysics Data System (ADS)

Over the past 8 years UHF radar meteor observations made at Arecibo Observatory (Puerto Rico) have evolved significantly while several long-standing meteor science issues have been solved and new ones raised. We start with a review of the current signal processing approach that includes significant new techniques with respect to identification of a meteor event and the eventual extraction of physical parameters. We then consider some basic radio science issues surrounding these observations. Current Doppler observations-now available with Doppler resolutions of <10m/s for meteor speeds ranging to nearly 100km/s-have underscored issues related to the speed-distribution of at least micrometeoroids. Radar scattering mechanisms and the possibility of bias in the reported observations are considered. Additionally, we emphasize that the technique described here is almost entirely distinct from the classical trail-echo meteor radars.

Mathews, J. D.; Doherty, J.; Wen, C.-H.; Briczinski, S. J.; Janches, D.; Meisel, D. D.

2003-07-01

80

Fall detection and classifications based on time-scale radar signal characteristics  

NASA Astrophysics Data System (ADS)

Unattended catastrophic falls result in risk to the lives of elderly. There are growing efforts and rising interest in detecting falls of the aging population, especially those living alone. Radar serves as an effective non-intrusive sensor for detecting human activities. For radar to be effective, it is important to achieve low false alarms, i.e., the system can reliably differentiate between a fall and other human activities. In this paper, we discuss the time-scale based signal analysis of the radar returns from a human target. Reliable features are extracted from the scalogram and are used for fall classifications. The classification results and the advantages of using a wavelet transform are discussed.

Gadde, Ajay; Amin, Moeness G.; Zhang, Yimin D.; Ahmad, Fauzia

2014-05-01

81

On optimal minimax jamming and detection of radar signals  

NASA Astrophysics Data System (ADS)

A game between an intelligent jammer J and decision maker DM is considered. DM seeks to detect a coherent, slowly fading narrowband signal using a Neyman-Pearson criterion. His observations are corrupted by additive narrowband noise, the source of which is J's jamming with a power constraint and otherwise almost arbitrary statistics. DM knows J's action but the converse is not true. When the number of samples increases asymptotically, a minimax solution for the game exists where the jamming is Gaussian, independent of the desired signal amplitude level and probability distribution. The same result also holds for detection of a nonrandom baseband signal.

Weiss, M.; Schwartz, S. C.

1985-05-01

82

Time-Frequency Distribution Analyses of Ku-Band Radar Doppler Echo Signals  

NASA Astrophysics Data System (ADS)

Real radar echo signals of a pedestrian, vehicle and group of helicopters are analyzed in order to maximize signal energy around central Doppler frequency in time-frequency plane. An optimization, preserving this concentration, is suggested based on three well-known concentration measures. Various window functions and time-frequency distributions were optimization inputs. Conducted experiments on an analytic and three real signals have shown that energy concentration significantly depends on used time-frequency distribution and window function, for all three used criteria.

Bujakovi?, Dimitrije; Andri?, Milenko; Bondžuli?, Boban; Mitrovi?, Sr?an; Simi?, Slobodan

2015-03-01

83

Cramer-Rao Bound for Gaussian Random Processes and Applications to Radar Processing of Atmospheric Signals  

NASA Technical Reports Server (NTRS)

Calculations of the exact Cramer-Rao Bound (CRB) for unbiased estimates of the mean frequency, signal power, and spectral width of Doppler radar/lidar signals (a Gaussian random process) are presented. Approximate CRB's are derived using the Discrete Fourier Transform (DFT). These approximate results are equal to the exact CRB when the DFT coefficients are mutually uncorrelated. Previous high SNR limits for CRB's are shown to be inaccurate because the discrete summations cannot be approximated with integration. The performance of an approximate maximum likelihood estimator for mean frequency approaches the exact CRB for moderate signal to noise ratio and moderate spectral width.

Frehlich, Rod

1993-01-01

84

Shuttle Imaging Radar - Physical controls on signal penetration and subsurface scattering in the Eastern Sahara  

NASA Technical Reports Server (NTRS)

Interpretation of Shuttle Imaging Radar-A (SIR-A) images by McCauley et al. (1982) dramatically changed previous concepts of the role that fluvial processes have played over the past 10,000 to 30 million years in shaping this now extremely flat, featureless, and hyperarid landscape. In the present paper, the near-surface stratigraphy, the electrical properties of materials, and the types of radar interfaces found to be responsible for different classes of SIR-A tonal response are summarized. The dominant factors related to efficient microwave signal penetration into the sediment blanket include (1) favorable distribution of particle sizes, (2) extremely low moisture content and (3) reduced geometric scattering at the SIR-A frequency (1.3 GHz). The depth of signal penetration that results in a recorded backscatter, here called 'radar imaging depth', was documented in the field to be a maximum of 1.5 m, or 0.25 of the calculated 'skin depth', for the sediment blanket. Radar imaging depth is estimated to be between 2 and 3 m for active sand dune materials. Diverse permittivity interfaces and volume scatterers within the shallow subsurface are responsible for most of the observed backscatter not directly attributable to grazing outcrops. Calcium carbonate nodules and rhizoliths concentrated in sandy alluvium of Pleistocene age south of Safsaf oasis in south Egypt provide effective contrast in premittivity and thus act as volume scatterers that enhance SIR-A portrayal of younger inset stream channels.

Schaber, G. G.; Mccauley, J. F.; Breed, C. S.; Olhoeft, G. R.

1986-01-01

85

Synthetic aperture radar signal data compression using block adaptive quantization  

NASA Technical Reports Server (NTRS)

This paper describes the design and testing of an on-board SAR signal data compression algorithm for ESA's ENVISAT satellite. The Block Adaptive Quantization (BAQ) algorithm was selected, and optimized for the various operational modes of the ASAR instrument. A flexible BAQ scheme was developed which allows a selection of compression ratio/image quality trade-offs. Test results show the high quality of the SAR images processed from the reconstructed signal data, and the feasibility of on-board implementation using a single ASIC.

Kuduvalli, Gopinath; Dutkiewicz, Melanie; Cumming, Ian

1994-01-01

86

A signal processing view of strip-mapping synthetic aperture radar  

NASA Technical Reports Server (NTRS)

The authors derive the fundamental strip-mapping SAR (synthetic aperture radar) imaging equations from first principles. They show that the resolution mechanism relies on the geometry of the imaging situation rather than on the Doppler effect. Both the airborne and spaceborne cases are considered. Range processing is discussed by presenting an analysis of pulse compression and formulating a mathematical model of the radar return signal. This formulation is used to obtain the airborne SAR model. The authors study the resolution mechanism and derive the signal processing relations needed to produce a high-resolution image. They introduce spotlight-mode SAR and briefly indicate how polar-format spotlight processing can be used in strip-mapping SAR. They discuss a number of current and future research directions in SAR imaging.

Munson, David C., Jr.; Visentin, Robert L.

1989-01-01

87

Knowledge-aided signal processing: a new paradigm for radar and other advanced sensors  

Microsoft Academic Search

Recently, significant progress has been made in the development of physics-based, knowledge-aided (KA) signal processing strategies supported by improvements in real-time embedded computing architectures. These developments provide designers of advanced sensor systems an unprecedented degree of flexibility when implementing next generation adaptive sensor systems. In the case of radar, this has been manifested in the first ever, real-time, KA space-time

WILLIAM L. MELVIN; JOSEPH R. GUERCI

2006-01-01

88

Shuttle Imaging Radar: Physical Controls on Signal Penetration and Subsurface Scattenng in the Eastern Sahara  

Microsoft Academic Search

SIR-A signal penetration and subsurface backscatter within the upper meter or so of the sediment blanket in the Eastern Sahara of southern Egypt and northern Sudan are enhanced both by radar sensor parameters and by the physical and chemical characteristics of eolian and alluvial materials. Interpretation of SIR-A images by McCauley et al. [1], [2] dramatically changed previous concepts of

GERALD G. SCHABER; JOHN F. McCAULEY; CAROL S. BREED; GARY R. OLHOEFT

1986-01-01

89

Comparative of signal processing techniques for micro-Doppler signature extraction with automotive radar systems  

NASA Astrophysics Data System (ADS)

In recent years, the automotive industry has experienced an evolution toward more powerful driver assistance systems that provide enhanced vehicle safety. These systems typically operate in the optical and microwave regions of the electromagnetic spectrum and have demonstrated high efficiency in collision and risk avoidance. Microwave radar systems are particularly relevant due to their operational robustness under adverse weather or illumination conditions. Our objective is to study different signal processing techniques suitable for extraction of accurate micro-Doppler signatures of slow moving objects in dense urban environments. Selection of the appropriate signal processing technique is crucial for the extraction of accurate micro-Doppler signatures that will lead to better results in a radar classifier system. For this purpose, we perform simulations of typical radar detection responses in common driving situations and conduct the analysis with several signal processing algorithms, including short time Fourier Transform, continuous wavelet or Kernel based analysis methods. We take into account factors such as the relative movement between the host vehicle and the target, and the non-stationary nature of the target's movement. A comparison of results reveals that short time Fourier Transform would be the best approach for detection and tracking purposes, while the continuous wavelet would be the best suited for classification purposes.

Rodriguez-Hervas, Berta; Maile, Michael; Flores, Benjamin C.

2014-05-01

90

Signal Generation for FMCW Ultra-Wideband Radar  

E-print Network

Ohm N=N0 F0=Freq_0 VCO_Freq=k0*_v 1 fre q VCO . v co n - N. VCO tu ne d N V_1Tone SRC4 Freq=Fref V=(1*exp(-j*pi/2)) V Figure 3.4-ADS Design for PLL The simulation is carried out to generate a 10 GHz RF signal that is phase locked... components equally spaced about the peak indicates that it is coming from amplitude modulation. 43 6.7 6.71 6.72 6.73 6.74 6.75 x 107 5 10 15 20 25 30 35 40 45 Beat Frequency at 67.22 MHz; Delay 3.425 us; Hanning window applied Am pl itu de [d B...

Patel, Aqsa Ejaz

2009-01-01

91

Dependence of radar signal strength on frequency and aspect angle of nonspecular meteor trails  

NASA Astrophysics Data System (ADS)

When a meteoroid penetrates Earth's atmosphere, it forms a high-density ionized plasma column immersed in the ionosphere between approximately 70 and 140 km altitude. High-power, large-aperture (HPLA) radars detect nonspecular trails when VHF or UHF radio waves reflect off structures in a turbulent meteor trail. These trails persist from a few milliseconds to many minutes and the return from these trails is referred to as nonspecular trails or range-spread trail echoes. In this paper, we present analysis of nonspecular trails detected with ALTAIR, which is an HPLA radar operating simultaneously at 160 MHz and 422 MHz on the Kwajalein Atoll. First, we investigate the aspect sensitivity of nonspecular trails and show that as the angle between the radar beam and the background magnetic field increases, the signal strength falls off 3 to 4 dB per degree at 160 MHz. For ALTAIR, this means that the aspect angle must be within approximately 12 degrees in order to detect nonspecular trails using the chosen waveforms. Second, we compare and contrast the meteoroids that form nonspecular trails and find that the meteoroid energy causes much of the variability in the nonspecular trail's signal-to-noise ratio (SNR) for a given aspect angle. In addition, we show two range-resolved fragmentation events that also affect the SNR. Finally, we determine the dependence of SNR on wavelength using two wavelengths and show that the maximum nonspecular trail SNR scales as approximately ?6, with a variation that depends upon altitude.

Close, S.; Hamlin, T.; Oppenheim, M.; Cox, L.; Colestock, P.

2008-06-01

92

Resolution function of nonsinusoidal radar signals. I - Range-velocity resolution with rectangular pulses  

Microsoft Academic Search

A generalization of a previously published ambiguity function that applies to radar known as large-relative-bandwidth radar, carrier-free radar, impulse radar, or nonsinusoidal radar is discussed. This radar has recently attracted attention because of its ability to penetrate absorbing materials used in the stealth technology. Another good application is the detection of moving targets with a small radar cross section by

Nasser J. Mohamed

1990-01-01

93

Resolution function of nonsinusoidal radar signals. I. Range-velocity resolution with rectangular pulses  

Microsoft Academic Search

A generalization of a previously published ambiguity function that applies to radar known as large-relative-bandwidth radar, carrier-free radar, impulse radar, or nonsinusoidal radar is discussed. This radar has attracted attention because of its ability to penetrate absorbing materials used in the stealth technology. Another good application is the detection of moving targets with a small radar cross section by a

N. J. Mohamed

1990-01-01

94

The application of digital signal processing techniques to a teleoperator radar system  

NASA Technical Reports Server (NTRS)

A digital signal processing system was studied for the determination of the spectral frequency distribution of echo signals from a teleoperator radar system. The system consisted of a sample and hold circuit, an analog to digital converter, a digital filter, and a Fast Fourier Transform. The system is interfaced to a 16 bit microprocessor. The microprocessor is programmed to control the complete digital signal processing. The digital filtering and Fast Fourier Transform functions are implemented by a S2815 digital filter/utility peripheral chip and a S2814A Fast Fourier Transform chip. The S2815 initially simulates a low-pass Butterworth filter with later expansion to complete filter circuit (bandpass and highpass) synthesizing.

Pujol, A.

1982-01-01

95

FFT methods in signal processing of the coal interface detector radar  

NASA Technical Reports Server (NTRS)

The FM radar for the coal interface detector, operating in the frequency band 2 to 4 GHz, is intended for the display of thicknesses between 2 cm and 20 cm. Because of such a short range, the thickness information is contained in the very few lowest spectral components of the output signal. To overcome this inconvenience, the Fourier series of the output signal was augmented to approximate a Fourier integral. This modification in the signal processing resulted in a higher spectral density, which in turn enabled an easier identification of the interface position in the laboratory. The orientation and spacing of the receiving and transmitting antennas is found to have an important influence on the system performance.

Kajfez, D.

1980-01-01

96

Propagating tsunami wave and subsequent resonant response signals detected by HF radar in the Kii Channel, Japan  

Microsoft Academic Search

Signals from the tsunami waves induced by the March 11, 2011 moment magnitude (Mw) 9.0 Tohoku-Oki earthquake and from subsequent resonances were detected as radial velocity variability by a high-frequency ocean surface radar (HF radar) installed on the eastern coast of the Kii Channel, at a range of about 1000 km from the epicenter along the eastern to southern coasts of

Hirofumi Hinata; Satoshi Fujii; Keita Furukawa; Tomoya Kataoka; Masafumi Miyata; Takashi Kobayashi; Masahiro Mizutani; Takahiro Kokai; Nobuyoshi Kanatsu

2011-01-01

97

Signal-to-Noise Ratio in Squeezed-Light Laser Radar  

E-print Network

The formalism for computing the signal-to-noise ratio (SNR) for laser radar is reviewed and applied to the tasks of target detection, direction-finding, and phase change estimation with squeezed light. The SNR for heterodyne detection of coherent light using a squeezed local oscillator is lower than that obtained using a coherent local oscillator. This is true for target detection, for phase estimation, and for direction-finding with a split detector. Squeezing the local oscillator also lowers SNR in balanced homodyne and heterodyne detection of coherent light. Loss places an upper bound on the improvement that squeezing can bring to direct-detection SNR.

Mark A. Rubin; Sumanth Kaushik

2009-07-30

98

Generation of high-range resolution radar signals using the Lorenz chaotic flow  

NASA Astrophysics Data System (ADS)

We propose a novel approach to generate chaotic Frequency Modulated (FM) signals with potential applications in highresolution radar imaging. The technique relies on the output of an n-dimensional (n>2) non-linear system that exhibits chaotic behavior. For simplicity, we have chosen the Lorenz system which has a set of three state variables x, y and z, and three control parameters ?, ?, and ?. FM signals are generated using any one of the state variables as the instantaneous frequency by varying the values of ? and ?. The obtained FM signal is ergodic and stationary and the time samples exhibit an invariant probability density function. The corresponding pseudo-phase orbits reveal themselves as a strange attractor that may take on the shape of a Mobius strip depending on the time evolution of the signal. A timefrequency analysis of the signal shows that the spectrum is centered on a time-dependent carrier frequency. Thus, the FM signal has a high time-bandwidth product similar to that of a chirp. However, the carrier frequency continuously shifts in a linear or quadratic pattern over a finite frequency range. A desirable feature of the signal is that the width of its autocorrelation's mainlobe approaches the reciprocal of the bandwidth. Furthermore, simulations show that the average of the time autocorrelation falls quickly and is void of sidelobes.

Pappu, Chandra S.; Flores, Benjamin C.

2010-04-01

99

On-Board Fiber-Optic Network Architectures for Radar and Avionics Signal Distribution  

NASA Technical Reports Server (NTRS)

Continued progress in both civil and military avionics applications is overstressing the capabilities of existing radio-frequency (RF) communication networks based on coaxial cables on board modem aircrafts. Future avionics systems will require high-bandwidth on- board communication links that are lightweight, immune to electromagnetic interference, and highly reliable. Fiber optic communication technology can meet all these challenges in a cost-effective manner. Recently, digital fiber-optic communication systems, where a fiber-optic network acts like a local area network (LAN) for digital data communications, have become a topic of extensive research and development. Although a fiber-optic system can be designed to transport radio-frequency (RF) signals, the digital fiber-optic systems under development today are not capable of transporting microwave and millimeter-wave RF signals used in radar and avionics systems on board an aircraft. Recent advances in fiber optic technology, especially wavelength division multiplexing (WDM), has opened a number of possibilities for designing on-board fiber optic networks, including all-optical networks for radar and avionics RF signal distribution. In this paper, we investigate a number of different novel approaches for fiber-optic transmission of on-board VHF and UHF RF signals using commercial off-the-shelf (COTS) components. The relative merits and demerits of each architecture are discussed, and the suitability of each architecture for particular applications is pointed out. All-optical approaches show better performance than other traditional approaches in terms of signal-to-noise ratio, power consumption, and weight requirements.

Alam, Mohammad F.; Atiquzzaman, Mohammed; Duncan, Bradley B.; Nguyen, Hung; Kunath, Richard

2000-01-01

100

Radar beam effects for a flight simulator using signal processor based hardware  

NASA Astrophysics Data System (ADS)

The design of a signal processor based system to simulate the beam-forming effects of airborne radars is presented. The problem is first formulated as a digital filtering operation with the filter response derived from the power distribution function of the radiating antenna. To lighten the computational load required for real-time simulation, an efficient finite impulse response (FIR) filter implementation proposed by Chu and Burrus (1984) is used. The algorithm, a unique implementation of FIR filters, is based on a polynomial approximation of the filter's response and results in significant reduction in the number of operations. In spite of this optimization, very high arithmetic throughput is still needed for real-time simulation. To design a system with the required capability, a high performance signal processor, the TMS320C30, was selected. The system also includes a data channel controller, an arbitration logic, fast memory elements, and a parallel interface to the host computer. The architecture is made modular, allowing many similar units to be teamed up and provide virtually unlimited computing power. The system is programmable and can simulate a variety of radar systems of different characteristics.

Nemer, E. J.; Bridegeman, R. C.; Malowany, A. S.

101

Radarclinometry - Bootstrapping the radar reflectance function from the image pixel-signal frequency distribution and an altimetry profile  

NASA Technical Reports Server (NTRS)

A method for determining the dependence of radar backscatter on incidence angle that is applicable to the region corresponding to a particular radar image is derived. The method is based on enforcing mathematical consistency between the frequency distribution of the images' pixel signals and a one-dimensional frequency distribution of slope component, which is obtained from a radar or laser altimetry profile in or near the imaged area. To test the resulting algorithm, an arbitrarily selected reflectance function is used to generate an artificial radar image from a digitized topographic map of the Lake Champlain West quadrangle in the Adirondack Mountains, U.S. It is found that, for 99 percent of the data, the maximum error is 1 degree.

Wildey, Robert L.

1988-01-01

102

Radarclinometry - Bootstrapping the radar reflectance function from the image pixel-signal frequency distribution and an altimetry profile  

NASA Astrophysics Data System (ADS)

A method for determining the dependence of radar backscatter on incidence angle that is applicable to the region corresponding to a particular radar image is derived. The method is based on enforcing mathematical consistency between the frequency distribution of the images' pixel signals and a one-dimensional frequency distribution of slope component, which is obtained from a radar or laser altimetry profile in or near the imaged area. To test the resulting algorithm, an arbitrarily selected reflectance function is used to generate an artificial radar image from a digitized topographic map of the Lake Champlain West quadrangle in the Adirondack Mountains, U.S. It is found that, for 99 percent of the data, the maximum error is 1 degree.

Wildey, Robert L.

1988-06-01

103

Polarimetric Radar Observations of Arctic Clouds: Signal Processing and First Results from the may 2013 Iop  

NASA Astrophysics Data System (ADS)

The ARM Climate Research Facility site at the North Slope of Alaska in Barrow provides polarimetric radar observations of Arctic clouds at X, Ka and W bands. During the May 2013 Scanning radar Intensive Observation Period, raw I and Q data were acquired with the X-SAPR and the Ka-W SACR for the purpose of validating existing, and testing new signal processing procedures specifically tailored for Arctic observations. The raw I and Q datasets were collected on May 3rd 2013 for the case of low-level boundary layer mixed-phase arctic clouds and on May 6th 2013 for the case of a synoptic low moving in from the west. http://www.arm.gov/campaigns/nsa2013nsasr The present paper describes the impact of signal processing procedures on the data, and establishes dual-polarization radar as a valuable tool for the microphysical characterization of ice clouds. In particular, the X-SAPR operates at STSR mode, making available differential reflectivity ZDR, copolar correlation coefficient ?hv, specific differential phase KDP and Degree of Polarization at Simultaneous Transmit DOPS. Low-level boundary layer mixed-phase Arctic clouds are characterized by layers of supercooled liquid water aloft, which present a stark polarimetric contrast with respect to the associated ice precipitation fallout. The ice particles falling from boundary layer Arctic clouds on May 2nd, 3rd and 4th 2013 (winds were very weak or absent) showed the remarkable property of being composed exclusively by large dendrites - fern-like, stellars, twelve-branched - indicating deposition as the main accretion mechanism. http://www.flickr.com/photos/michele_galletti/sets/72157633422079814/ Boundary Layer mixed-phase Arctic clouds provide an exceptional natural laboratory for the exploration of polarimetric signatures in presence of dendritic ice particles. The first-ever X-band analysis of differential reflectivity ZDR of mixed-phase Arctic clouds is presented in [1]. For the May 6th case, ice particle populations associated with frontal systems underwent more significant vertical mixing, and therefore more significant break-up and aggregation, with the overall result that ice particles possessed less geometrical symmetry, and consequently less prominent polarimetric contrast was detected by the radars. [1] Oue, Galletti, Verlinde "Observations of X-band differential reflectivity in Arctic mixed-phase clouds", submitted.

Galletti, M.; Oue, M.; Verlinde, J.

2013-12-01

104

Numerical and Physical Modeling of the Effects of Temperature Change on Ground Penetrating Radar Signals  

NASA Astrophysics Data System (ADS)

Ground-penetrating radar (GPR) is widely used for subsurface characterization in environmental contaminant remediation studies. GPR can be used to detect the extent of the contaminant plume and monitor the remediation process as contaminants are removed. Thermal remediation methods, such as steam injection, are used to mobilize non-aqueous phase liquids (NAPLs) for vapor extraction; these methods cause a temperature change in earth materials, which subsequently causes variations in GPR signal response. When using GPR to monitor a remediation process, it is critical to account for all possible factors that affect GPR signatures for better definition and delineation of contaminant flow and transport. Numerical and physical models were used to quantify the effects of temperature changes and fluid phase changes in a porous medium. The numerical modeling shows that when a porous media is heated, the GPR signal will show both a decrease in traveltime and an increase in amplitude from a reflector. A simplified numerical model of the GPR signal response to a steam injection, characteristic of some thermal remediation methods, was made by comparing GPR signal responses to a water-filled layer and an air-filled (steam) layer within the saturated porous medium. The polarity of the reflected GPR signal is opposite for the water- and air-filled layers. The results from physical experiments conducted in a laboratory-scale sand tank confirm the results obtained from the numerical models.

Kochiss, C. S.; Liu, L.

2004-05-01

105

Advanced signal processing method for ground penetrating radar feature detection and enhancement  

NASA Astrophysics Data System (ADS)

This paper focuses on new signal processing algorithms customized for an air coupled Ultra-Wideband (UWB) Ground Penetrating Radar (GPR) system targeting highway pavements and bridge deck inspections. The GPR hardware consists of a high-voltage pulse generator, a high speed 8 GSps real time data acquisition unit, and a customized field-programmable gate array (FPGA) control element. In comparison to most existing GPR system with low survey speeds, this system can survey at normal highway speed (60 mph) with a high horizontal resolution of up to 10 scans per centimeter. Due to the complexity and uncertainty of subsurface media, the GPR signal processing is important but challenging. In this GPR system, an adaptive GPR signal processing algorithm using Curvelet Transform, 2D high pass filtering and exponential scaling is proposed to alleviate noise and clutter while the subsurface features are preserved and enhanced. First, Curvelet Transform is used to remove the environmental and systematic noises while maintain the range resolution of the B-Scan image. Then, mathematical models for cylinder-shaped object and clutter are built. A two-dimension (2D) filter based on these models removes clutter and enhances the hyperbola feature in a B-Scan image. Finally, an exponential scaling method is applied to compensate the signal attenuation in subsurface materials and to improve the desired signal feature. For performance test and validation, rebar detection experiments and subsurface feature inspection in laboratory and field configurations are performed.

Zhang, Yu; Venkatachalam, Anbu Selvam; Huston, Dryver; Xia, Tian

2014-03-01

106

Understanding the Signal Structure in DVB-T Signals for Passive Radar Detection  

E-print Network

Definition: The MPEG-2 stream first passes through a series of stages including bit-randomization, outer- coding, and inner-coding before being mapped into the signal constellation. This process results

Nehorai, Arye

107

Physics-based deformations of ground penetrating radar signals to improve the detection of buried explosives  

NASA Astrophysics Data System (ADS)

A number of recent algorithms have shown improved performance in detecting buried explosive threats by statistically modeling target responses observed in ground penetrating radar (GPR) signals. These methods extract features from known examples of target responses to train a statistical classifier. The statistical classifiers are then used to identify targets emplaced in previously unseen conditions. Due to the variation in target GPR responses caused by factors such as differing soil conditions, classifiers require training on a large, varied dataset to encompass the signal variation expected in operational conditions. These training collections generally involve burying each target type in a number of soil conditions, at a number of burial depths. The cost associated with both burying the targets, and collecting the data is extremely high. Thus, the conditions and depths sampled cover only a subset of possible scenarios. The goal of this research is to improve the ability of a classifier to generalize to new conditions by deforming target responses in accordance with the physical properties of GPR signals. These signal deformations can simulate a target response under different conditions than those represented in the data collection. This research shows that improved detection performance in previously unseen conditions can be achieved by utilizing deformations, even when the training dataset is limited.

Sakaguchi, Rayn T.; Morton, Kennth D.; Collins, Leslie M.; Torrione, Peter A.

2014-05-01

108

30 ENGINEERING & SCIENCE WI NTE R 2012 Whether processing radar signals in Norway or assessing rock properties in Nigeria, Calte  

E-print Network

of genetic engineering in Ireland; he helped establish the Smurfit Institute of Genetics in 1998, where he30 ENGINEERING & SCIENCE WI NTE R 2012 Whether processing radar signals in Norway or assessing rock, England, Sarah Ferguson, BS '08, Engineering & Applied Science (CNS) Sarah Ferguson is a trader at Ronin

109

Evaluation of environmental radioxenon isotopical signals from a singular large source emitter  

NASA Astrophysics Data System (ADS)

In the framework of the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) the atmospheric background of environmental radioxenon is been studied near areas that could be affected by man-made sources. It was recently shown that radiopharmaceutical facilities (RPF) make a major contribution to the general background of 133Xe and other xenon isotopes both in the northern and southern hemisphere. The daily IMS noble gas measurements around the globe are influenced from such anthropogenic sources that could mask radioxenon signals from a nuclear explosion. To distinguish a nuclear explosion signal from releases from civil nuclear facilities, not only the activity concentration but also the ratio of different radioxenon isotopes (131mXe, 133mXe, 133Xe and 135Xe) plays a crucial role, since the ratios can be used to discriminate source types. Theoretical release and ratio studies were recently published, but no measurements close to radiopharmaceutical facilities have ever been performed. The world's fourth largest radiopharmaceutical facility, NTP Radioisotopes Ltd, is located in Pelindaba, South Africa. Other than a small nuclear power plant, located 1300 km southwest, near Cape Town and a small research reactor in the DR of Congo, located 2700 km northwest, this is the only facility that is known to emit any radioxenon on the African continent south of the Equator. This source is likely very dominant with respect to xenon emission. This makes it a point source, which is a unique situation, as all other worldwide large radiopharmaceutical facilities are situated in regions surrounded by many other nuclear facilities. Between 10 November and 22 December 2008, radioxenon was measured continuously with a radioactive xenon measurement system, at the North-West University, Mafikeng, South Africa, which is situated 250 km northwest of Pelindaba. Fifty-six 12-hour samples were measured with a beta-gamma coincidence detector, of which 55 contained 133Xe with values between 0.11 and 27.1 mBq/m3. Eleven samples contained 135Xe and three samples 133mXe. It is furthermore worth mentioning that none of the samples contained 131mXe. In parallel, stack samples were taken at the NTP facility on an almost daily basis and measured with a high purity germanium gamma detector nearby at a local laboratory of NECSA. These stack measurements correspond to a daily release of around 1-10 TBq. This is consistent with typical release rates published for this type of facility and well below exposure guidelines thus not dangerous to the public. On the other hand it is expected to be high enough to increase the radioxenon background in wide regions around such facilities and has a potential impact on the monitoring capability of the highly sensitive CTBT xenon monitoring systems. This paper will report on the activities measured at the facility stack and in Mafikeng, which allows for analysis and comparison with activity predictions based on atmospheric transport modelling. Finally the activity ratios measured shall be discussed in view of their implication for the xenon monitoring capability of the CTBT verification regime. Disclaimer The views expressed in this publication are those of the authors and do not necessarily reflect the views of the CTBTO Preparatory Commission or any of the institutions mentioned herein. . Acknowledgement This project is performed in the framework of European Council Joint Action no. 2007/468/CFSP on support for activities of the Preparatory Commission of the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO) monitoring and verification capabilities in the framework of the implementation of the European Union Strategy against Proliferation of Weapons of Mass Destruction.

Saey, P. R. J.; Bowyer, T. W.; Aldener, M.; Becker, A.; Cooper, M. W.; Elmgren, K.; Faanhof, A.; Hayes, J. C.; Hosticka, B.; Lidey, L. S.

2009-04-01

110

Validation of a new signal processing scheme for the MST radar at Aberystwyth  

NASA Astrophysics Data System (ADS)

This paper describes a new signal processing scheme for the 46.5 MHz Doppler Beam Swinging wind-profiling radar at Aberystwyth, in the UK. Although the techniques used are similar to those already described in literature i.e. the identification of multiple signal components within each spectrum and the use of radial- and time-continuity algorithms for quality-control purposes it is shown that they must be adapted for the specific meteorological environment above Aberystwyth. In particular they need to take into account the three primary causes of unwanted signals: ground clutter, interference, and Rayleigh scatter from hydrometeors under stratiform precipitation conditions. Attention is also paid to the fact that short-period gravity-wave activity can lead to an invalidation of the fundamental assumption of the wind field remaining stationary over the temporal and spatial scales encompassed by a cycle of observation. Methods of identifying and accounting for such conditions are described. The random measurement error associated with horizontal wind components is estimated to be 3.0 4.0 m s-1 for single cycle data. This reduces to 2.0 3.0 m s-1 for data averaged over 30 min. The random measurement error associated with vertical wind components is estimated to be 0.2 0.3 m s-1. This cannot be reduced by time-averaging as significant natural variability is expected over intervals of just a few minutes under conditions of short-period gravity-wave activity.

Hooper, D. A.; Nash, J.; Oakley, T.; Turp, M.

2008-10-01

111

Array geometries, signal type, and sampling conditions for the application of compressed sensing in MIMO radar  

E-print Network

in MIMO radar Juan Lopeza and Zhijun Qiaoa aDepartment of Mathematics, The University of Texas - Pan American, Edinburg, Texas, 78539, USA ABSTRACT MIMO radar utilizes the transmission and reflection illustrate erroneous reconstructions when the conditions are not satisfied. Keywords: MIMO radar, compressed

Qiao, Zhijun "George" - Department of Mathematics, University of Texas

112

On the extraction of directional sea-wave spectra from synthetic- aperture radar-signal arrays without matched filtering.  

USGS Publications Warehouse

An economical method of digitally extracting sea-wave spectra from synthetic-aperture radar-signal records, which can be performed routinely in real or near-real time with the reception of telemetry from Seasat satellites, would be of value to a variety of scientific disciplines. This paper explores techniques for such data extraction and concludes that the mere fact that the desired result is devoid of phase information does not, of itself, lead to a simplification in data processing because of the nature of the modulation performed on the radar pulse by the backscattering surface. -from Author

Wildey, R.L.

1980-01-01

113

Emitter Geolocation with Multiple UAVs  

Microsoft Academic Search

Geolocation of radar and communication emitters based on time difference of arrivals (TDOAs) can be carried out using a network of three or four unmanned aerial vehicles (UAVs) each of which is equipped with an electronic warfare support (ES) sensor, a global positioning system (GPS) receiver, a precision clock and a limited bandwidth communication system. When the leading edge of

Nickens Okello

2006-01-01

114

Data processing of ground-penetrating radar signals for the detection of discontinuities using polarization diversity  

NASA Astrophysics Data System (ADS)

In civil engineering, ground penetrating radar (GPR) is used to survey pavement thickness at traffic speed, detect and localize buried objects (pipes, cables, voids, cavities), zones of cracks and discontinuities in concrete or soils. In this work, a ground-coupled radar made of a pair of transmitting and receiving bowtie-slot antennas is moved linearly on the soil surface to detect the reflected waves induced by discontinuities in the subsurface. The GPR system operates in the frequency domain using a step-frequency continuous wave (SFCW) using a Vector Network Analyzer (VNA) in an ultra-wide band [0.3 ; 4] GHz. The detection of targets is usually focused on time imaging. Thus, the targets (limited in size) are usually shown by diffraction hyperbolas on a Bscan image that is an unfocused depiction of the scatterers. The contrast in permittivity and the ratio between the size of the object and the wavelength are important parameters in the detection process. Thus, we have made a first study on the use of polarization diversity to obtain additional information relative to the contrast between the soil and the target and the dielectric characteristics of a target. The two main polarizations configurations of the radar have been considered in the presence of objects having a pipe geometry: the TM (Transverse Magnetic) and TE (Transverse Electric. To interpret the diffraction hyperbolas on a Bscan image, we have used pre-processing techniques are necessary to reduce the clutter signal which can overlap and obscure the target responses, particularly shallow objects. The clutter, which can be composed of the direct coupling between the antennas and the reflected wave from the soil surface, the scattering on the heterogeneities due to the granular nature of the subsurface material, and some additive noise, varies with soil dielectric characteristics and/or surface roughness and leads to uncertainty in the measurements (additive noise). Because of the statistical nature of the clutter, we have considered and quantified the performance of the Principal Component Analysis (PCA) and the Independent Component Analysis (ICA) in remove or minimizing the clutter using the receiver operating characteristics (ROC) graph. The study has been focused in the preferred polarization on simulated and experimental scenarios of soil structures with a few parameters such as the presence of a different target depths which are capable to perturb the first arrival times made of clutter components, and different dielectric characteristics (conductive or dielectric) of a given target (pipe).

Tebchrany, Elias; Sagnard, Florence; Baltazart, Vincent; Tarel, Jean-Phillippe

2014-05-01

115

Propagating tsunami wave and subsequent resonant response signals detected by HF radar in the Kii Channel, Japan  

NASA Astrophysics Data System (ADS)

Signals from the tsunami waves induced by the March 11, 2011 moment magnitude ( M w) 9.0 Tohoku-Oki earthquake and from subsequent resonances were detected as radial velocity variability by a high-frequency ocean surface radar (HF radar) installed on the eastern coast of the Kii Channel, at a range of about 1000 km from the epicenter along the eastern to southern coasts of Honshu Island. A time-distance diagram of band-passed (9-200 min) radial velocity along the beam reveals that the tsunami waves propagated from the continental shelf slope to the inner channel as progressive waves for the first three waves, and then natural oscillations were excited by the waves; and that the direction of the tsunami wave propagation and the axis of the natural oscillations differed from that of the radar beam. In addition, spectral analyses of the radial velocities and sea surface heights obtained in the channel and on the continental shelf slope suggest complex natural oscillation modes excited by the tsunami waves. The major advantage of the HF radars as tsunami detection is early warning as the tsunami is still far offshore. There is no doubt on this importance beside still technical and operational studies are needed. Our results adds a new role of the HF radars to measure the detailed surface current fields with high spatiotemporal resolution toward understanding detailed processes of resonant response to tsunami waves in coastal regions.

Hinata, Hirofumi; Fujii, Satoshi; Furukawa, Keita; Kataoka, Tomoya; Miyata, Masafumi; Kobayashi, Takashi; Mizutani, Masahiro; Kokai, Takahiro; Kanatsu, Nobuyoshi

2011-11-01

116

The design and development of signal-processing algorithms for an airborne x-band Doppler weather radar  

NASA Technical Reports Server (NTRS)

Improved measurements of precipitation will aid our understanding of the role of latent heating on global circulations. Spaceborne meteorological sensors such as the planned precipitation radar and microwave radiometers on the Tropical Rainfall Measurement Mission (TRMM) provide for the first time a comprehensive means of making these global measurements. Pre-TRMM activities include development of precipitation algorithms using existing satellite data, computer simulations, and measurements from limited aircraft campaigns. Since the TRMM radar will be the first spaceborne precipitation radar, there is limited experience with such measurements, and only recently have airborne radars become available that can attempt to address the issue of the limitations of a spaceborne radar. There are many questions regarding how much attenuation occurs in various cloud types and the effect of cloud vertical motions on the estimation of precipitation rates. The EDOP program being developed by NASA GSFC will provide data useful for testing both rain-retrieval algorithms and the importance of vertical motions on the rain measurements. The purpose of this report is to describe the design and development of real-time embedded parallel algorithms used by EDOP to extract reflectivity and Doppler products (velocity, spectrum width, and signal-to-noise ratio) as the first step in the aforementioned goals.

Nicholson, Shaun R.

1994-01-01

117

Analysis and improved design considerations for airborne pulse Doppler radar signal processing in the detection of hazardous windshear  

NASA Technical Reports Server (NTRS)

High resolution windspeed profile measurements are needed to provide reliable detection of hazardous low altitude windshear with an airborne pulse Doppler radar. The system phase noise in a Doppler weather radar may degrade the spectrum moment estimation quality and the clutter cancellation capability which are important in windshear detection. Also the bias due to weather return Doppler spectrum skewness may cause large errors in pulse pair spectral parameter estimates. These effects are analyzed for the improvement of an airborne Doppler weather radar signal processing design. A method is presented for the direct measurement of windspeed gradient using low pulse repetition frequency (PRF) radar. This spatial gradient is essential in obtaining the windshear hazard index. As an alternative, the modified Prony method is suggested as a spectrum mode estimator for both the clutter and weather signal. Estimation of Doppler spectrum modes may provide the desired windshear hazard information without the need of any preliminary processing requirement such as clutter filtering. The results obtained by processing a NASA simulation model output support consideration of mode identification as one component of a windshear detection algorithm.

Lee, Jonggil

1990-01-01

118

Estimation of High-Frequency Earth-Space Radio Wave Signals via Ground-Based Polarimetric Radar Observations  

NASA Technical Reports Server (NTRS)

Expanding human presence in space, and enabling the commercialization of this frontier, is part of the strategic goals for NASA's Human Exploration and Development of Space (HEDS) enterprise. Future near-Earth and planetary missions will support the use of high-frequency Earth-space communication systems. Additionally, increased commercial demand on low-frequency Earth-space links in the S- and C-band spectra have led to increased interest in the use of higher frequencies in regions like Ku and Ka-band. Attenuation of high-frequency signals, due to a precipitating medium, can be quite severe and can cause considerable disruptions in a communications link that traverses such a medium. Previously, ground radar measurements were made along the Earth-space path and compared to satellite beacon data that was transmitted to a ground station. In this paper, quantitative estimation of the attenuation along the propagation path is made via inter-comparisons of radar data taken from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) and ground-based polarimetric radar observations. Theoretical relationships between the expected specific attenuation (k) of spaceborne measurements with ground-based measurements of reflectivity (Zh) and differential propagation phase shift (Kdp) are developed for various hydrometeors that could be present along the propagation path, which are used to estimate the two-way path-integrated attenuation (PIA) on the PR return echo. Resolution volume matching and alignment of the radar systems is performed, and a direct comparison of PR return echo with ground radar attenuation estimates is made directly on a beam-by-beam basis. The technique is validated using data collected from the TExas and Florida UNderflights (TEFLUN-B) experiment and the TRMM large Biosphere-Atmosphere experiment in Amazonia (LBA) campaign. Attenuation estimation derived from this method can be used for strategiC planning of communication systems for future HEDS missions.

Bolen, Steve; Chandrasekar, V.

2002-01-01

119

Lunar ground penetrating radar: Minimizing potential data artifacts caused by signal interaction with a rover body  

NASA Astrophysics Data System (ADS)

Ground-penetrating radar (GPR) is the leading geophysical candidate technology for future lunar missions aimed at mapping shallow stratigraphy (<5 m). The instrument's exploration depth and resolution capabilities in lunar materials, as well as its small size and lightweight components, make it a very attractive option from both a scientific and engineering perspective. However, the interaction between a GPR signal and the rover body is poorly understood and must be investigated prior to a space mission. In doing so, engineering and survey design strategies should be developed to enhance GPR performance in the context of the scientific question being asked. This paper explores the effects of a rover (simulated with a vertical metal plate) on GPR results for a range of heights above the surface and antenna configurations at two sites: (i) a standard GPR testing site with targets of known position, size, and material properties, and; (ii) a frozen lake for surface reflectivity experiments. Our results demonstrate that the GPR antenna configuration is a key variable dictating instrument design, with the XX polarization considered optimal for minimizing data artifact generation. These findings could thus be used to help guide design requirements for an eventual flight instrument.

Angelopoulos, Michael; Redman, David; Pollard, Wayne H.; Haltigin, Timothy W.; Dietrich, Peter

2014-11-01

120

Spectral analysis of ground penetrating radar signals in concrete, metallic and plastic targets  

NASA Astrophysics Data System (ADS)

The accuracy of detecting buried targets using ground penetrating radar (GPR) depends mainly on features that are extracted from the data. The objective of this study is to test three spectral features and evaluate the quality to provide a good discrimination among three types of materials (concrete, metallic and plastic) using the 200 MHz GPR system. The spectral features which were selected to check the interaction of the electromagnetic wave with the type of material are: the power spectral density (PSD), short-time Fourier transform (STFT) and the Wigner-Ville distribution (WVD). The analyses were performed with simulated data varying the sizes of the targets and the electrical properties (relative dielectric permittivity and electrical conductivity) of the soil. To check if the simulated data are in accordance with the real data, the same approach was applied on the data obtained in the IAG/USP test site. A noticeable difference was found in the amplitude of the studies' features in the frequency domain and these results show the strength of the signal processing to try to differentiate buried materials using GPR, and so can be used in urban planning and geotechnical studies.

Santos, Vinicius Rafael N. dos; Al-Nuaimy, Waleed; Porsani, Jorge Luís; Hirata, Nina S. Tomita; Alzubi, Hamzah S.

2014-01-01

121

Robust multiplatform RF emitter localization  

NASA Astrophysics Data System (ADS)

In recent years, position based services has increase. Thus, recent developments in communications and RF technology have enabled system concept formulations and designs for low-cost radar systems using state-of-the-art software radio modules. This research is done to investigate a novel multi-platform RF emitter localization technique denoted as Position-Adaptive RF Direction Finding (PADF). The formulation is based on the investigation of iterative path-loss (i.e., Path Loss Exponent, or PLE) metrics estimates that are measured across multiple platforms in order to autonomously adapt (i.e. self-adjust) of the location of each distributed/cooperative platform. Experiments conducted at the Air-Force Research laboratory (AFRL) indicate that this position-adaptive approach exhibits potential for accurate emitter localization in challenging embedded multipath environments such as in urban environments. The focus of this paper is on the robustness of the distributed approach to RF-based location tracking. In order to localize the transmitter, we use the Received Signal Strength Indicator (RSSI) data to approximate distance from the transmitter to the revolving receivers. We provide an algorithm for on-line estimation of the Path Loss Exponent (PLE) that is used in modeling the distance based on Received Signal Strength (RSS) measurements. The emitter position estimation is calculated based on surrounding sensors RSS values using Least-Square Estimation (LSE). The PADF has been tested on a number of different configurations in the laboratory via the design and implementation of four IRIS wireless sensor nodes as receivers and one hidden sensor as a transmitter during the localization phase. The robustness of detecting the transmitters position is initiated by getting the RSSI data through experiments and then data manipulation in MATLAB will determine the robustness of each node and ultimately that of each configuration. The parameters that are used in the functions are the median values of RSSI and rms values. From the result it is determined which configurations possess high robustness. High values obtained from the robustness function indicate high robustness, while low values indicate lower robustness.

Al Issa, Huthaifa; Ordóñez, Raúl

2012-06-01

122

Parametric Velocity Synthetic Aperture Radar:Signal Modeling and Optimal Methods  

Microsoft Academic Search

Velocity synthetic aperture radar (VSAR) is equipped with a linear array to receive the echoes from a radar illuminating area via multiple channels, each of which can reconstruct a reflectivity image for the same stationary scene. Based on analysis of pixel vector sampled among multi-images, VSAR may effectively suppress the strong ground clutter and improve moving target detection and location.

Jia Xu; Gang Li; Ying-Ning Peng; Xiang-Gen Xia; Yong-Liang Wang

2008-01-01

123

Extended Emitter Target Tracking Using GM-PHD Filter  

PubMed Central

If equipped with several radar emitters, a target will produce more than one measurement per time step and is denoted as an extended target. However, due to the requirement of all possible measurement set partitions, the exact probability hypothesis density filter for extended target tracking is computationally intractable. To reduce the computational burden, a fast partitioning algorithm based on hierarchy clustering is proposed in this paper. It combines the two most similar cells to obtain new partitions step by step. The pseudo-likelihoods in the Gaussian-mixture probability hypothesis density filter can then be computed iteratively. Furthermore, considering the additional measurement information from the emitter target, the signal feature is also used in partitioning the measurement set to improve the tracking performance. The simulation results show that the proposed method can perform better with lower computational complexity in scenarios with different clutter densities. PMID:25490206

Zhu, Youqing; Zhou, Shilin; Gao, Gui; Zou, Huanxin; Lei, Lin

2014-01-01

124

1796 IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 62, NO. 7, APRIL 1, 2014 Sub-Nyquist Radar via Doppler Focusing  

E-print Network

of a monostatic pulse-Doppler radar transceiver trying to detect targets sparsely populated in the radar, monostatic, narrow-band system. Targets are non-fluctuating point targets, sparsely populated in the radar

Eldar, Yonina

125

Automotive radar  

NASA Astrophysics Data System (ADS)

Radar networks for automtovie short-range applications (up to 30m) based on powerful but inexpensive 24GHz high range resolution pulse or FMCW radar systems have been developed at the Technical University of Hamburg-Harburg. The described system has been integrated in to an experimental vehicle and tested in real street environment. This paper considers the general network design, the individual pulse or FMCW radar sensors, the network signal processing scheme, the tracking procedure and possible automotive applications, respectively. Object position estimation is accomplished by the very precise range measurement of each individual sensor and additional trilateration procedures. The paper concludes with some results obtained in realistic traffic conditions with multiple target situations using 24 GHz radar network.

Rohling, Hermann

2004-07-01

126

Synthetic aperture radar interferometry  

Microsoft Academic Search

Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristic of the surface. By exploiting the phase of the coherent radar signal, interferometry has transformed radar remote sensing from a largely interpretive science to a quantitative tool, with applications in cartography, geodesy, land cover

PAUL A. ROSEN; SCOTT HENSLEY; IAN R. JOUGHIN; FUK K. LI; SØREN N. MADSEN; ERNESTO RODRÍGUEZ; RICHARD M. GOLDSTEIN

2000-01-01

127

Velocity and acceleration estimation of Doppler weather radar\\/lidar signals in colored noise  

Microsoft Academic Search

The authors are interested in estimating the Doppler shift occurred in weather radar returns, which yields precipitation velocity information. Conventional techniques including the pulse pair processor rely heavily on the assumption that the additive noise is white and hence their performance degrades when the noise color is unknown. Because the data length for a given range gate is usually small,

Weige Chen; Guotong Zhou; G. B. Giannakis

1995-01-01

128

Measured spectrum and polarization of wideband radar signal from forest stand  

Microsoft Academic Search

We report on an experiment regarding the spectra of super-wide band radar (SWBR) backscatter amplitude generated by forest canopy. The larch forest stand of 100 × 100 m2, used as an object of study, was located 50 km to the north from the city of Krasnoyarsk, Russia, with the average tree height, diameter, and density of trees being of 14.2

V. P. Yakubov; E. D. Telpukhovskiy; N. A. Moiseenko; V. L. Mironov

2004-01-01

129

Approaches and techniques for elimination of ionospheric phase distortions in orbital ground penetrating radar signals  

Microsoft Academic Search

Investigation of the interior of Mars is of great interest now. An efficient mean of such exploration is a spacecraft ground-penetrating radar. At present, several projects of this kind are under development or operation (MARSIS, ShaRad and Nozomi). Most planets and their moons have ionospheres with certain densities. Martian ionosphere is known to have a critical frequency up to 4

Ya. A. Ilyushin; V. E. Kunitsyn

2004-01-01

130

Synthetic aperture radar interferometry using one bit coded raw and reference signals  

Microsoft Academic Search

This paper is concerned about the generation of interferometric phase patterns using synthetic aperture radar (SAR) images obtained by processing the raw data and reference function both quantized at one bit (Signum Coded). Such processing technique involves one-bit coded (i.e., binary) sequences, and can be efficiently implemented in real time using very simple and low cost hardware. It is shown

Gianfranco Fornaro; Vito Pascazio; Gilda Schirinzi

1997-01-01

131

Spectral signal to clutter and thermal noise properties of ocean wave imaging synthetic aperture radars  

Microsoft Academic Search

The high wavenumber detection cut-off is determined above which the spectrum of ocean waves imaged by a synthetic aperture radar (SAR) is lost in the background noise spectrum consisting of the clutter noise associated with the Rayleigh statistics of the backscattering surface and the thermal noise originating in the SAR system itself. For given power, the maximum detection cut-off wavenumber

Werner Alpers; Klaus Hasselmann

1982-01-01

132

A combined analogue and digital pulse compression system using large time bandwidth product signals for use in synthetic aperture radar  

NASA Astrophysics Data System (ADS)

Pulse compression, widely used in modern radar systems, has the advantage in that it allows the use of long duration low-power pulses which facilitate low-power transmission. A synthetic aperture radar (SAR) pulse compression system able to compress very large time bandwidth product signals while still retaining high dynamic range capability and flexibility would be very advantageous. The possibility of implementing the compression in two stages is investigated, in which the first stage compression processing is done by an analog device followed by digital techniques in the second stage. Various signal coding methods were evaluated to determine those most suitable to the two-stage process, and various means of implementing the second stage were compared. A two-stage pulse compression system was then designed and built to generate arbitrarily coded expanded pulses with bandwidths in excess of 200 MHz. Its performance was evaluated in the presence of tone, noise, and jamming. It was shown that the two-stage pulse compression system exhibited greater resistance to quantizer saturation than a comparable digital system. The processing effort required to implement the compression using a digital adaptive matched filter was found to be slightly less than double that of a basic pulse compression system.

Godbole, Pushkar E.

1989-07-01

133

Browse > Conferences> Radar Conference, 2008. RADAR ... INDEX TERMS  

E-print Network

Browse > Conferences> Radar Conference, 2008. RADAR ... INDEX TERMS REFERENCES CITING DOCUMENTS Force, MorphoAnalysis in Signal Process. Lab., Salon-de-Provence This paper appears in: Radar Conference, 2008. RADAR '08. IEEE Issue Date: 26-30 May 2008 On page(s): 1 - 5 Location: Rome ISSN: 1097-5659 Print

Préaux, Jean-Philippe

134

Ground-penetrating radar methods  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ground-penetrating radar geophysical methods are finding greater and greater use in agriculture. With the ground-penetrating radar (GPR) method, an electromagnetic radio energy (radar) pulse is directed into the subsurface, followed by measurement of the elapsed time taken by the radar signal as it ...

135

Powerful ultrawideband rf emitters: status and challenges  

Microsoft Academic Search

Ultra-wideband emitters are of interest for a variety of potential applications that range from radar transmitters to communications applications. This technology is of current interest to the USAF Phillips Laboratory where theoretical and experimental efforts have been underway for a number of years. Research into the production of ultra-wideband sources at the Phillips Laboratory has been accomplished along several different

Forrest J. Agee; David W. Scholfield; William Prather; Jeffrey W. Burger

1995-01-01

136

Signal analysis by means of time-frequency (Wigner-type) distributions -- Applications to sonar and radar echoes  

SciTech Connect

Time series data have been traditionally analyzed in either the time or the frequency domains. For signals with a time-varying frequency content, the combined time-frequency (TF) representations, based on the Cohen class of (generalized) Wigner distributions (WD`s) offer a powerful analysis tool. Using them, it is possible to: (1) trace the time-evolution of the resonance features usually present in a standard sonar cross section (SCS), or in a radar cross section (RCS) and (2) extract target information that may be difficult to even notice in an ordinary SCS or RCS. After a brief review of the fundamental properties of the WD, the authors discuss ways to reduce or suppress the cross term interference that appears in the WD of multicomponent systems. These points are illustrated with a variety of three-dimensional (3-D) plots of Wigner and pseudo-Wigner distributions (PWD), in which the strength of the distribution is depicted as the height of a Wigner surface with height scales measured by various color shades or pseudocolors. The authors also review studies they have made of the echoes returned by conducting or dielectric targets in the atmosphere, when they are illuminated by broadband radar pings. A TF domain analysis of these impulse radar returns demonstrates their superior informative content. These plots allow the identification of targets in an easier and clearer fashion than by the conventional RCS of narrowband systems. The authors show computed and measured plots of WD and PWD of various types of aircraft to illustrate the classification advantages of the approach at any aspect angle. They also show analogous results for metallic objects buried underground, in dielectric media, at various depths.

Gaunaurd, G. [Naval Surface Warfare Center, Silver Spring, MD (United States). Carderock Div.] [Naval Surface Warfare Center, Silver Spring, MD (United States). Carderock Div.; Strifors, H.C. [National Defense Research Establishment, Stockholm (Sweden)] [National Defense Research Establishment, Stockholm (Sweden)

1996-09-01

137

Research on a kind of high precision and fast signal processing algorithm for FM/CW laser radar  

NASA Astrophysics Data System (ADS)

Range accuracy and efficiency are two important indicators for Frequency modulated continuous wave (FM/CW) laser radar, improving the accuracy and efficiency of extracting beat frequency are key factors for them. Multiple Modulation Zoom Spectrum Analysis (ZFFT) and the Chirp-Z Transform (CZT) are two widely used methods for improving frequency estimation. The paper through analyze advantages and disadvantages of these methods, proposes a high accuracy and fast signal processing method which is ZFFT-CZT, it combines advantages that ZFFT can reduce data size, and CZT can zoom in frequency of any interested band. The processing of ZFFT-CZT is following: firstly ZFFT is conducted by conducting Fourier transform on short time signal to calculate amount of frequency shift, and transforming high-frequency signal into low-frequency signal of long time sampling, then CZT is conducted by choosing any interested band to continue subdividing the spectral peaks, which can reduce picket fence effect. By simulate experiment based on ZFFT-CZT method, two closed targets at distance of 50m and 50.001m are measured, and the measurement errors are 40?m and 34?m respectively. It proved that ZFFT-CZT has a small amount of calculation, which can meet the requirement of high precision frequency extraction.

Xu, Xinke; Liu, Guodong; Chen, Fengdong; Liu, Bingguo; Zhuang, Zhitao; Lu, Cheng; Gan, Yu

2014-12-01

138

Single Platform Emitter Location AOA(DF) FOA Interferometery TOA  

E-print Network

Single Platform Emitter Location AOA(DF) FOA Interferometery TOA SBI LBI Emitter Location is Two) Frequency-of-Arrival (FOA) or Doppler d) Angle-of-Arrival (AOA) 2) Use Signal Parameters Measured at Several

Fowler, Mark

139

Sub-nanosecond ranging possibilities of optical radar at various signal levels and transmitted pulse widths  

NASA Technical Reports Server (NTRS)

The behavior of the photomultiplier is considered, as well as the method of derivation of the photomultiplier output pulse and its relation to the reflected light pulse width and amplitude, and the calibration of range precision and accuracy. Pulsed laser radars with light pulse widths of 30, 3, and 0.1 nanosec a considered, with the 0.1 nanosec system capable of highest precision in several modes of operation, including a high repetition rate, single photoelectron reception mode. An alternate calibration scheme using a fast, triggerable light pulser is described in detail.

Poultney, S. K.

1971-01-01

140

Emittance Exchange Results  

SciTech Connect

The promise of next-generation light sources depends on the availability of ultra-low emittance electron sources. One method of producing low transverse emittance beams is to generate a low longitudinal emittance beam and exchange it with a large transverse emittance. Experiments are underway at Fermilab's A0 Photoinjector and ANL's Argonne Wakefield Accelerator using the exchange scheme of Kim and Sessler. The experiment at the A0 Photoinjector exchanges a large longitudinal emittance with a small transverse emittance. AWA expects to exchange a large transverse emittance with a small longitudinal emittance. In this paper we discuss recent results at A0 and AWA and future plans for these experiments.

Fliller III,R.; Koeth, T.

2009-05-04

141

Emittance exchange results  

SciTech Connect

The promise of next-generation light sources depends on the availability of ultra-low emittance electron sources. One method of producing low transverse emittance beams is to generate a low longitudinal emittance beam and exchange it with a large transverse emittance. Experiments are underway at Fermilab's A0 Photoinjector and ANL's Argonne Wakefield Accelerator using the exchange scheme of Kim and Sessler. The experiment at the A0 Photoinjector exchanges a large longitudinal emittance with a small transverse emittance. AWA expects to exchange a large transverse emittance with a small longitudinal emittance. In this paper we discuss recent results at A0 and AWA and future plans for these experiments.

Fliller, R.P., III; /Brookhaven; Koeth, T.; /Rutgers U., Piscataway

2009-09-01

142

Effects of Signal Processing and Antenna Frequency on the Geostatistical Structure of Ground-Penetrating Radar Data  

E-print Network

-Penetrating Radar Data Greg A. Oldenborger1 , Michael D. Knoll and Warren Barrash Center for Geophysical suggested that the geostatistical structure of ground-penetrating radar data may be representative of the spatial structure of hydraulic properties. However, radar images of the subsurface can change drastically

Barrash, Warren

143

Doppler frequency in interplanetary radar and general relativity  

NASA Technical Reports Server (NTRS)

The change of frequency of an interplanetary radar signal sent from the earth to another planet or to a space probe is worked out according to general relativity. The Schwarzschild spacetime is employed and its null geodesics control the motion of the signals. Exact Doppler frequency formulas are derived for one-way and two-way radar in terms of an arbitrary Schwarzschild radial coordinate. A reduction to the special relativity case is used to interpret the formulas in terms of the relative radial velocity of emitter and target. The general relativity corrections are worked out approximately for each of three possible Schwarzschild radial coordinates, and a numerical example is given. The amount of the correction is different according as one or the other of the Schwarzschild coordinates is identified with the radius vector deduced from classical celestial mechanics. The identification problem is discussed.

Mcvittie, G. C.

1972-01-01

144

Asymmetrical field emitter  

DOEpatents

Providing a field emitter with an asymmetrical emitter structure having a very sharp tip in close proximity to its gate. One preferred embodiment of the present invention includes an asymmetrical emitter and a gate. The emitter having a tip and a side is coupled to a substrate. The gate is connected to a step in the substrate. The step has a top surface and a side wall that is substantially parallel to the side of the emitter. The tip of the emitter is in close proximity to the gate. The emitter is at an emitter potential, and the gate is at a gate potential such that with the two potentials at appropriate values, electrons are emitted from the emitter. In one embodiment, the gate is separated from the emitter by an oxide layer, and the emitter is etched anisotropically to form its tip and its asymmetrical structure.

Fleming, James G. (Albuquerque, NM); Smith, Bradley K. (Albuquerque, NM)

1995-01-01

145

Threshold detection of radar signals off the sea surface in non-Gaussian clutter and deterministic interference: II - statistical analysis of ROI surface data  

SciTech Connect

The purpose of this report is to motivate and outline a program of data analysis, for data obtained from radar returns from ocean surfaces perturbed by internal waves and wind-wave interactions. The ultimate aims of this analysis are to provide the appropriate statistics of the signals returned from these ocean surfaces for: (1) use in implementing and evaluating optimum and near-optimum signal processing procedures for detecting and evaluating (i.e., measuring) these internal wave effects and, (2) to provide quantitative physical insight into both the surface scatter and subsurface mechanisms which determine the received radar signals. Here the focus is initially on the needed statistics of the radar returns. These are primarily: (i) the (instantaneous) amplitude and envelope probability densities, (pdf`s) and distributions (PDFS) of the returns and, (ii) analogous statistics for the intensities (associated with the pixel data). Also required are: (iii) space-time covariance data of the returns, for further improvement of detection capabilities. Preliminary evidence and earlier experiments suggest that these data [(i), (ii)] are nongaussian and strongly so at times. This in turn, if not properly taken into account, can greatly degrade signal detection in the usual weak-signal regimes [1],[2].

Middleton, D.

1996-05-02

146

Improving on police radar  

Microsoft Academic Search

The use of lasers, cameras, and advanced signal processing to help isolate individual offenders on crowded highways is discussed. The limitations of the predominant radar in use today, namely down-the-road Doppler-radar in which the axis of the antenna is directed along the line of travel of the target vehicle, are described. The potential of video records, across-the-road radar, and both

P. D. Fisher

1992-01-01

147

Support vector data description for detecting the air-ground interface in ground penetrating radar signals  

Microsoft Academic Search

In using GPR images for landmine detection it is often useful to identify the air-ground interface in the GRP signal for alignment purposes. A common simple technique for doing this is to assume that the highest return in an A-scan is from the reflection due to the ground and to use that as the location of the interface. However there

Joshua Wood; Joseph Wilson

2011-01-01

148

Synthetic Aperture Radar Simulation On Radar Terrain Clutter  

Microsoft Academic Search

The subject of this paper is related to a new method of Synthetic Aperture Radar (i.e., SAR) simulation on radar terrain clutter. Usually, images are simulated at pixel level after Doppler compression. In this case this study deals with the simulation of the raw signal at the output of the antenna i.e. for each pulse emitted by the radar during

ARMAND Pierre; VIDAL-MADJAR Daniel

1992-01-01

149

Emittance Theory for Thin Film Selective Emitter  

NASA Technical Reports Server (NTRS)

Thin films of high temperature garnet materials such as yttrium aluminum garnet (YAG) doped with rare earths are currently being investigated as selective emitters. This paper presents a radiative transfer analysis of the thin film emitter. From this analysis the emitter efficiency and power density are calculated. Results based on measured extinction coefficients for erbium-YAG and holmium-YAG are presented. These results indicated that emitter efficiencies of 50 percent and power densities of several watts/sq cm are attainable at moderate temperatures (less than 1750 K).

Chubb, Donald L.; Lowe, Roland A.; Good, Brian S.

1994-01-01

150

Comparison of algorithms for finding the air-ground interface in ground penetrating radar signals  

Microsoft Academic Search

In using GPR images for landmine detection it is often useful to identify the air-ground interface in the GPR signal for alignment purposes. A number of algorithms have been proposed to solve the air-ground interface detection problem, including some which use only A-scan data, and others which track the ground in B-scans or C-scans. Here we develop a framework for

Joshua Wood; Jeremy Bolton; George Casella; Leslie Collins; Paul Gader; Taylor Glenn; Jeffery Ho; Wen Lee; Richard Mueller; Brandon Smock; Peter Torrione; Ken Watford; Joseph Wilson

2011-01-01

151

Frequency-based target localization methods for widely separated MIMO radar  

NASA Astrophysics Data System (ADS)

Frequency-based localization methods are widely used to find emitter locations. Several techniques are described in the literature for emitter localization based on Doppler frequency shifts. These techniques can be used efficiently for emitter localization by using narrowband signals. Although these methods are simple and efficient, the application to the radar systems for target localization is very limited. In this paper, a new low-complexity target localization method, Target Localization via Doppler Frequencies (TLDF), for Doppler-only Multi-Input, Multi-Output (MIMO) radar with widely separated stations is described. By using widely separated MIMO radars with unmodulated continuous wave signals, the received frequencies and the Doppler shifts can be estimated efficiently. The position and the velocity of the target can be found from these estimated frequencies by a search in the position space. As the Doppler frequency is estimated efficiently, not only the target velocity but also the direction of the target is estimated accurately with the TLDF method. The Cramer-Rao Bounds (CRB) are calculated for the target velocity and the target position estimations in two-dimensional space. In simulations, the proposed method is compared with the iso-Doppler curves-based traditional method and with the CRB for different geometries. The performance of the proposed method is not affected from the target amplitude fluctuations because of its frequency-based nature. Finally, the comparison between the frequency-only MIMO radar and the pulsed monostatic radar is investigated, and the simplicity and the efficiency of the proposed method are demonstrated.

Kalkan, Y.��lmaz; Baykal, Buyurman

2014-01-01

152

Non-detection of impulsive radio signals from lightning in Martian dust storms using the radar receiver on the Mars Express spacecraft  

Microsoft Academic Search

Here we report the results of a nearly five-year search for impulsive radio signals from lightning discharges in Martian dust storms using the radar receiver on the Mars Express spacecraft. The search covered altitudes from 275 km to 1400 km and frequencies from 4.0 to 5.5 MHz with a time resolution of 91.4 ?s and a detection threshold of 2.8

D. A. Gurnett; D. D. Morgan; L. J. Granroth; B. A. Cantor; W. M. Farrell; J. R. Espley

2010-01-01

153

CHIRP Doppler radar  

NASA Astrophysics Data System (ADS)

The present investigation is concerned with the concept of a combination of the clinical procedure of reconstruction tomography with the radar processing for linear FM pulse compression. An approach based on such a combination is to be employed to map radar backscatter energy. Radar systems employing pulse compression of linear frequency modulated (CHIRP) pulses are considered along with the inversion formula employed by reconstruction tomography. The conventional system enabling radar backscatter mapping is based on pulse-Doppler radar which basically incorporates range-gated spectrum analysis. CHIRP Doppler radar represents a potential alternative. Advantages are related to an absence of requirements to maintain coherence from pulse to pulse, and the suppression of interference due to second-time-around signals. Raabe (1976) has discussed an application involving the imaging of the wakes of reentering space vehicles.

Bernfeld, M.

1984-04-01

154

Emittance Theory for Cylindrical Fiber Selective Emitter  

NASA Technical Reports Server (NTRS)

A fibrous rare earth selective emitter is approximated as an infinitely long, cylinder. The spectral emittance, e(sub x), is obtained L- by solving the radiative transfer equations with appropriate boundary conditions and uniform temperature. For optical depth, K(sub R), where alpha(sub lambda), is the extinction coefficient and R is the cylinder radius, greater than 1 the spectral emittance depths, K(sub R) alpha(sub lambda)R, is nearly at its maximum value. There is an optimum cylinder radius, R(sub opt) for maximum emitter efficiency, n(sub E). Values for R(sub opt) are strongly dependent on the number of emission bands of the material. The optimum radius decreases slowly with increasing emitter temperature, while the maximum efficiency and useful radiated power increase rapidly with increasing, temperature.

Chubb, Donald L.

1998-01-01

155

Floating emitter solar cell  

NASA Technical Reports Server (NTRS)

A front surface contact floating emitter solar cell transistor is provided in a semiconductor body (n-type), in which floating emitter sections (p-type) are diffused or implanted in the front surface. Between the emitter sections, a further section is diffused or implanted in the front surface, but isolated from the floating emitter sections, for use either as a base contact to the n-type semiconductor body, in which case the section is doped n+, or as a collector for the adjacent emitter sections.

Chih, Sah (inventor); Cheng, Li-Jen (inventor)

1987-01-01

156

Linear frequency modulation photoacoustic radar: optimal bandwidth and signal-to-noise ratio for frequency-domain imaging of turbid media.  

PubMed

The development of the pulse compression photoacoustic (PA) radar using linear frequency modulation (LFM) demonstrated experimentally that spectral matching of the signal to the ultrasonic transducer bandwidth does not necessarily produce the best PA signal-to-noise ratio, and it was shown that the optical and acoustic properties of the absorber will modify the optimal bandwidth. The effects of these factors are investigated in frequency-domain (FD) PA imaging by employing one-dimensional and axisymmetric models of the PA effect, and a Krimholtz-Leedom-Matthaei model for the employed transducers. LFM chirps with various bandwidths were utilized and transducer sensitivity was measured to ensure the accuracy of the model. The theory was compared with experimental results and it was shown that the PA effect can act as a low-pass filter in the signal generation. Furthermore, with the PA radar, the low-frequency behavior of two-dimensional wave generation can appear as a false peak in the cross correlation signal trace. These effects are important in optimizing controllable features of the FD-PA method to improve image quality. PMID:21895073

Lashkari, Bahman; Mandelis, Andreas

2011-09-01

157

Radar Detection using Sparsely Distributed Apertures in Urban Environment  

E-print Network

Radar Detection using Sparsely Distributed Apertures in Urban Environment Il-Young Sona, Trond in detection performance compared to conventional matched filtering. Keywords: Radar detection, Distributed antenna, Radar data processing, Statistical signal pro- cessing 1. INTRODUCTION Conventional matched

Yazici, Birsen

158

Electromagnetic interference impact of the proposed emitters for the High Frequency Active Auroral Research Program (HAARP)  

Microsoft Academic Search

The proposed HAARP emitters at the Gakona (Alaska) preferred site and at the Clear AFS (Alaska) alternative site are the Ionospheric Research Instrument (IRI), the Incoherent Scatter Radar (ISR), and the Vertical Incidence Sounder (VIS). The electromagnetic interference (EMI) impact of those emitters on receiving systems in the vicinity of the sites is estimated in this study. The results are

G. A. Robertshaw; A. L. Snyder; M. M. Weiner

1993-01-01

159

A pulse Doppler radar using reconfigurable computing  

Microsoft Academic Search

In a variety of signal processing applications, nowadays, the use of radar for advanced control has become a necessity, e.g., navigational systems, aircraft, automobiles and other sensing devices. A normal microprocessor based radar signal processor eats a lot of processing power and time so we have proposed the implementation of a dynamically reconfigurable pulsed Doppler radar in a mixed system

S. Sumeen; M. Mobien; M. I. Siddiqi

2003-01-01

160

Radar Technology Applied to Air Traffic Control  

Microsoft Academic Search

Use of primary radars for air traffic control (ATC) is discussed. The location and the parameters of various ATC radars are described. The clutter environment (land clutter, birds, automobiles, and weather) has had a major impact on the configuration of these radars. Signal-processing techniques and antenna techniques utilized to cope with the clutter are described. Future signal-processing techniques for the

WILLIAM W. SHRADER

1973-01-01

161

Radar Imaging of Non-Uniformly Rotating Targets via a Novel Approach for Multi-Component AM-FM Signal Parameter Estimation.  

PubMed

A novel radar imaging approach for non-uniformly rotating targets is proposed in this study. It is assumed that the maneuverability of the non-cooperative target is severe, and the received signal in a range cell can be modeled as multi-component amplitude-modulated and frequency-modulated (AM-FM) signals after motion compensation. Then, the modified version of Chirplet decomposition (MCD) based on the integrated high order ambiguity function (IHAF) is presented for the parameter estimation of AM-FM signals, and the corresponding high quality instantaneous ISAR images can be obtained from the estimated parameters. Compared with the MCD algorithm based on the generalized cubic phase function (GCPF) in the authors' previous paper, the novel algorithm presented in this paper is more accurate and efficient, and the results with simulated and real data demonstrate the superiority of the proposed method. PMID:25806870

Wang, Yong

2015-01-01

162

Detection of active emitters using triangulation and trilateration techniques: Theory and practice  

NASA Astrophysics Data System (ADS)

Recent conflicts have highlighted the benefits of 'soft-kill' electronic warfare (stand off, escort, and self screening jamming), during intrusion into areas protected by Air Defence (AD) radar networks. These conflicts have highlighted the need to protect and supplement the Recognized Air Picture (RAP) with the ability to locate and track the intruding jammers. A Passive Jammer Location (PJL) system, and some of the theory behind it, currently under development at the Marconi Research Center are described. The two basic geometrical techniques for locating unknown emitters, usually termed triangulation and trilateration, are identified. The main problems associated with triangulation techniques, those of target ghosts and ghost resolution in denser scenarios, are discussed and trilateration processing using correlation offered as a solution. The main feature of an operational PJL system is noted as being the need to positively resolve jammer positions, to sub-beam accuracy, in dense jamming scenarios. This includes the 'pop-up' target appearing over the radar horizon and the agile sophisticated jammer. In addition a number of other features are identified which would be desirable in any future NATO PJL system. Over a number of years the UK MoD and GEC-Marconi have undertaken a number of studies relating to PJL architectures and data processing techniques. In 1991 these studies led to the Air Defence Emitter Location Equipment (ADELE) Technology Demonstrator. The objectives of the ADELE program are to demonstrate that the requirements of a PJL system can be met at a price affordable by AD system procurers. Additionally to confirm that the new PJL data processing techniques, developed during these previous studies, perform as predicted during live trials. The main hardware and software modules making up the ADELE demonstrator are discussed including: the multi beam antenna, the resistive matrix beam former, the PJL multi-channel signal sampling hardware, radar interfaces and synchronization, signal and data processing, display and recording, and simulation resources.

Dean, A. M.

1992-11-01

163

Technology: Photonics illuminates the future of radar  

NASA Astrophysics Data System (ADS)

The first implementation of a fully photonics-based coherent radar system shows how photonic methods for radio-frequency signal generation and measurement may facilitate the development of software-defined radar systems. See Letter p.341

McKinney, Jason D.

2014-03-01

164

Obstacle penetrating dynamic radar imaging system  

DOEpatents

An obstacle penetrating dynamic radar imaging system for the detection, tracking, and imaging of an individual, animal, or object comprising a multiplicity of low power ultra wideband radar units that produce a set of return radar signals from the individual, animal, or object, and a processing system for said set of return radar signals for detection, tracking, and imaging of the individual, animal, or object. The system provides a radar video system for detecting and tracking an individual, animal, or object by producing a set of return radar signals from the individual, animal, or object with a multiplicity of low power ultra wideband radar units, and processing said set of return radar signals for detecting and tracking of the individual, animal, or object.

Romero, Carlos E. (Livermore, CA); Zumstein, James E. (Livermore, CA); Chang, John T. (Danville, CA); Leach, Jr.. Richard R. (Castro Valley, CA)

2006-12-12

165

Photonically engineered incandescent emitter  

DOEpatents

A photonically engineered incandescence is disclosed. The emitter materials and photonic crystal structure can be chosen to modify or suppress thermal radiation above a cutoff wavelength, causing the emitter to selectively emit in the visible and near-infrared portions of the spectrum. An efficient incandescent lamp is enabled thereby. A method for fabricating a three-dimensional photonic crystal of a structural material, suitable for the incandescent emitter, is also disclosed.

Gee, James M.; Lin, Shawn-Yu; Fleming, James G.; Moreno, James B.

2003-08-26

166

Photonically Engineered Incandescent Emitter  

DOEpatents

A photonically engineered incandescence is disclosed. The emitter materials and photonic crystal structure can be chosen to modify or suppress thermal radiation above a cutoff wavelength, causing the emitter to selectively emit in the visible and near-infrared portions of the spectrum. An efficient incandescent lamp is enabled thereby. A method for fabricating a three-dimensional photonic crystal of a structural material, suitable for the incandescent emitter, is also disclosed.

Gee, James M. (Albuquerque, NM); Lin, Shawn-Yu (Albuquerque, NM); Fleming, James G. (Albuquerque, NM); Moreno, James B. (Albuquerque, NM)

2005-03-22

167

Phase Calibration Of Radar Polarimetric Data  

NASA Technical Reports Server (NTRS)

Technique for phase calibration of data acquired by airborne imaging radar polarimeter based on extraction of calibration parameters from data themselves. Enables use of data-compression technique to reduce volume of data in synthetic-aperture-radar correlator. Typical radar polarimeter includes transmitting and receiving channels for horizontally and vertically polarized signals. Phase delay in each channel usually known only approximately if at all. Consequently, necessary to phase-calibrate radar return signals.

Zebker, Howard A.; Lou, Yunling

1990-01-01

168

Methods of emittance measurement  

Microsoft Academic Search

We discuss experimental techniques for measurement of the density of beam particles in both the transverse and longitudinal phase space. The second moments of a two-dimensional density in conjugate coordinates are combined to form the emittance, which remains invariant under idealized beam transport. Four different methods of emittance measurement are presented, as will be implemented at the Brookhaven Accelerator Test

K. T. McDonald; D. P. Russell

169

Methods of emittance measurement  

Microsoft Academic Search

We discuss experimental techniques for measurement of the density of beam particles in both the transverse and longitudinal phase space. The second moments of a two-dimensional density in conjugate coordinates are combined to form the emittance, which remains invariant under idealized beam transport. Four different methods of emittance measurement are presented, as will be implemented at the Brookhaven Accelerator Test

K. T. McDonald; D. P. Russell

1989-01-01

170

Diamond fiber field emitters  

DOEpatents

A field emission electron emitter comprising an electrode formed of at least one diamond, diamond-like carbon or glassy carbon composite fiber, said composite fiber having a non-diamond core and a diamond, diamond-like carbon or glassy carbon coating on said non-diamond core, and electronic devices employing such a field emission electron emitter.

Blanchet-Fincher, Graciela B. (Wilmington, DE); Coates, Don M. (Santa Fe, NM); Devlin, David J. (Los Alamos, NM); Eaton, David F. (Wilmington, DE); Silzars, Aris K. (Landenburg, PA); Valone, Steven M. (Santa Fe, NM)

1996-01-01

171

Pulsed hybrid field emitter  

DOEpatents

A hybrid emitter exploits the electric field created by a rapidly depoled ferroelectric material. Combining the emission properties of a planar thin film diamond emitter with a ferroelectric alleviates the present technological problems associated with both types of emitters and provides a robust, extremely long life, high current density cathode of the type required by emerging microwave power generation, accelerator technology and display applications. This new hybrid emitter is easy to fabricate and not susceptible to the same failures which plague microstructure field emitter technology. Local electrode geometries and electric field are determined independently from those for optimum transport and brightness preservation. Due to the large amount of surface charge created on the ferroelectric, the emitted electrons have significant energy, thus eliminating the requirement for specialized phosphors in emissive flat-panel displays. 11 figs.

Sampayan, S.E.

1998-03-03

172

Emitter Localization and Visualization (ELVIS): A Backward Ray Tracing Algorithm for Locating Emitters  

E-print Network

the emergency personnel, such as police, fire-fighters etc., for both tactical and rescue purposes. Except signal strength. There are multiple methods based on this approach: RADAR [3] uses empirically

173

Radar Entomology  

NSDL National Science Digital Library

Radar tracking used to profile insect migration, mating and flight patterns. Many links to various pages include current workers in radar entomology, historical uses of the technology, and many images.

0000-00-00

174

Radar principles  

NASA Technical Reports Server (NTRS)

Discussed here is a kind of radar called atmospheric radar, which has as its target clear air echoes from the earth's atmosphere produced by fluctuations of the atmospheric index of refraction. Topics reviewed include the vertical structure of the atmosphere, the radio refractive index and its fluctuations, the radar equation (a relation between transmitted and received power), radar equations for distributed targets and spectral echoes, near field correction, pulsed waveforms, the Doppler principle, and velocity field measurements.

Sato, Toru

1989-01-01

175

Application of field emitter arrays to microwave power amplifiers  

Microsoft Academic Search

This paper describes the operation of a field emitter array (FEA) as the electron source of a traveling-wave tube (TWT) amplifier. Issues of beam control and focus at high current density and low magnetic field are addressed as well as issues relating to the inherent high emittance of the FEA beam and cathode protection from ion bombardment. Large signal, nonlinear

David R. Whaley; Bartley M. Gannon; Carl R. Smith; Carter M. Armstrong; Capp A. Spindt

2000-01-01

176

A controlled experiment to investigate the correlation between early-time signal attributes of ground-coupled radar and soil dielectric properties  

NASA Astrophysics Data System (ADS)

Ground-coupled radar has been used in the literature to estimate shallow subsoil permittivity using ground-wave velocity measurements. It has also been shown that the electromagnetic (EM) properties of the soil significantly affect antenna performance, modifying in particular the amplitude, shape, and duration of the 'early-time' Ground Penetrating Radar (GPR) signals. To quantitatively evaluate these effects we built a test site consisting of a 4 × 7 × 1.2 m volume filled primarily with sand; this volume is hydraulically isolated from the surroundings and contains buried pipes in which water can be introduced or removed to control the level of the water table. On a regular grid of 28 points we measured the soil dielectric properties at depth intervals of 0-10 and 0-20 cm using Time Domain Reflectometry (TDR) probes, and collected GPR data using both 250 and 500 MHz bistatic antennas. The measurements were performed with the water table at different depths to systematically change the shallow-soil dielectric properties. Relative permittivity and conductivity values were calculated from the TDR data, and the average envelopes of the first half cycle of the early-time GPR signals were computed. Data analysis shows a high degree of linear correlation (r ? 0.8) between the early-time signal attributes for both antenna frequencies and the EM properties obtained using both TDR probe lengths. The highest correlation (r = 0.9) was found between the 500 MHz data and the permittivity measured along the 0-20 cm depth interval; this relationship is explained in terms of ground wave penetration. The results of our investigation confirm previous field observations and are in full agreement with theoretical predictions and related numerical simulations, highlighting the potential for alternative convenient approaches to predict EM properties of the shallow subsoil.

Pettinelli, Elena; Di Matteo, Andrea; Beaubien, Stanley Eugene; Mattei, Elisabetta; Lauro, Sebastian Emanuel; Galli, Alessandro; Vannaroni, Giuliano

2014-02-01

177

Radar applications overview  

NASA Astrophysics Data System (ADS)

During the fifty years since its initial development as a means of providing early warning of airborne attacks against allied countries during World War II, radar systems have developed to the point of being highly mobile and versatile systems capable of supporting a wide variety of remote sensing applications. Instead of being tied to stationary land-based sites, radar systems have found their way into highly mobile land vehicles as well as into aircraft, missiles, and ships of all sizes. Of all these applications, however, the most exciting revolution has occurred in the airborne platform arena where advanced technology radars can be found in all shapes and sizes...ranging from the large AWACS and Joint STARS long range surveillance and targeting systems to small millimeter wave multi-spectral sensors on smart weapons that can detect and identify their targets through the use of highly sophisticated digital signal processing hardware and software. This paper presents an overview of these radar applications with the emphasis on modern airborne sensors that span the RF spectrum. It will identify and describe the factors that influence the parameters of low frequency and ultra wide band radars designed to penetrate ground and dense foliage environments and locate within them buried mines, enemy armor, and other concealed or camouflaged weapons of war. It will similarly examine the factors that lead to the development of airborne radar systems that support long range extended endurance airborne surveillance platforms designed to detect and precision-located both small high speed airborne threats as well as highly mobile time critical moving and stationary surface vehicles. The mission needs and associated radar design impacts will be contrasted with those of radar systems designed for high maneuverability rapid acquisition tactical strike warfare platforms, and shorter range cued air-to-surface weapons with integral smart radar sensors.

Greenspan, Marshall

1996-06-01

178

Microwave Doppler radar in unobtrusive health monitoring  

NASA Astrophysics Data System (ADS)

This article frames the use of microwave Doppler radar in the context of ubiquitous, non-obstructive health monitoring. The use of a 24GHz CW (continuous wave) Doppler radar based on a commercial off-the-shelf transceiver for remote sensing of heart rate and respiration rate based on the acquisition and processing of the signals delivered by the radar is briefly presented.

Silva Girão, P.; Postolache, O.; Postolache, G.; Ramos, P. M.; Dias Pereira, J. M.

2015-02-01

179

Laser Assisted Emittance Exchange  

SciTech Connect

We describe here the laser assisted emittance exchange (LAEE) technique. A laser operating in the transverse mode (TEM10 or TEM01) is used to interact with the electron beam in a dispersive region and to initiate the transverse-to-longitudinal emittance exchange. It is shown that with the LAEE one can generate an electron beam with ultralow transverse emittance, which allows one to significantly bring down the size of an X-ray free electron laser (FEL) and greatly extend the availability of these light sources. The technique can also be used to enhance the performances of X-ray FELs in storage rings. The timing and energy jitter problems for the standard emittance exchange and LAEE techniques are also discussed.

Xiang, Dao; /SLAC

2012-06-11

180

DIAMOND SECONDARY EMITTER  

SciTech Connect

We present the design and experimental progress on the diamond secondary emitter as an electron source for high average power injectors. The design criteria for average currents up to 1 A and charge up to 20 nC are established. Secondary Electron Yield (SEY) exceeding 200 in transmission mode and 50 in emission mode have been measured. Preliminary results on the design and fabrication of the self contained capsule with primary electron source and secondary electron emitter will also be presented.

BEN-ZVI, I.; RAO, T.; BURRILL, A.; CHANG, X.; GRIMES, J.; RANK, J.; SEGALOV, Z.; SMEDLEY, J.

2005-10-09

181

Shuttle orbiter radar cross-sectional analysis  

NASA Technical Reports Server (NTRS)

Theoretical and model simulation studies on signal to noise levels and shuttle radar cross section are described. Pre-mission system calibrations, system configuration, and postmission system calibration of the tracking radars are described. Conversion of target range, azimuth, and elevation into radar centered east north vertical position coordinates are evaluated. The location of the impinging rf energy with respect to the target vehicles body axis triad is calculated. Cross section correlation between the two radars is presented.

Cooper, D. W.; James, R.

1979-01-01

182

Iterative Adaptive Approaches to MIMO Radar Imaging  

Microsoft Academic Search

Multiple-input multiple-output (MIMO) radar can achieve superior performance through waveform diversity over conventional phased-array radar systems. When a MIMO radar transmits orthogonal waveforms, the reflected signals from scatterers are linearly independent of each other. Therefore, adaptive receive filters, such as Capon and amplitude and phase estimation (APES) filters, can be directly employed in MIMO radar applications. High levels of noise

William Roberts; Petre Stoica; Jian Li; Tarik Yardibi; Firooz A. Sadjadi

2010-01-01

183

Electromagnetic interference impact of the proposed emitters for the High Frequency Active Auroral Research Program (HAARP). Interim report  

Microsoft Academic Search

The proposed HAARP emitters at the Gakona (Alaska) preferred site and at the Clear AFS (Alaska) alternative site are the Ionospheric Research Instrument (IRI), the Incoherent Scatter Radar (ISR), and the Vertical Incidence Sounder(VIS). The electromagnetic interference (EMI) impact of those emitters on receiving systems in the vicinity of the sites is estimated in this study. The results are intended

G. A. Robertshaw; A. L. Snyder; M. M. Weiner

1993-01-01

184

Emittance Degradation Measurements  

NASA Astrophysics Data System (ADS)

The emittance blow-up due to Coherent Synchrotron Radiation (CSR) and Centrifugal Space Charge Force (CSCF) is presently a critical point in the design of future linear colliders and linac driven X-ray FELs (LCLS, Tesla...). Theory predicts that, given the very high peak current required, the small normalised emittance can be degraded while passing through a bunch compressor and through a long undulator. At the Sunshine (Stanford University Short Intense Electron Source) facility, we propose to check experimentally the validity of theoretical formulae related to CSR and CSCF using a 4m long undulator. With a normalised emittance of 20 mm.mrad and a peak current of 250 A, we expect to measure a 60 mm.mrad increase in normalised emittance each from the CSR and also from the CSCF, leading to a 140 mm.mrad final normalised emittance. The experimental set-up has been completed. Measurements are being performed and will be described in the paper.

Limborg, C.; Hernandez, M.; Settakorn, C.; Wiedemann, H.

1997-05-01

185

Electrochemical formation of field emitters  

DOEpatents

Electrochemical formation of field emitters, particularly useful in the fabrication of flat panel displays. The fabrication involves field emitting points in a gated field emitter structure. Metal field emitters are formed by electroplating and the shape of the formed emitter is controlled by the potential imposed on the gate as well as on a separate counter electrode. This allows sharp emitters to be formed in a more inexpensive and manufacturable process than vacuum deposition processes used at present. The fabrication process involves etching of the gate metal and the dielectric layer down to the resistor layer, and then electroplating the etched area and forming an electroplated emitter point in the etched area.

Bernhardt, Anthony F. (Berkeley, CA)

1999-01-01

186

Spaceborne radar  

NASA Technical Reports Server (NTRS)

The spaceborne radar panel considered how radar could be used to measure precipitation from satellites. The emphasis was on how radar could be used with radiometry (at microwave, visible (VIS), and infrared (IR) wavelengths) to reduce the uncertainties of measuring precipitation with radiometry alone. In addition, the fundamental electromagnetic interactions involved in the measurements were discussed to determine the key work areas for research and development to produce effective instruments. Various approaches to implementing radar systems on satellites were considered for both shared and dedicated instruments. Finally, a research and development strategy was proposed for establishing the parametric relations and retrieval algorithms required for extracting precipitation information from the radar and associated radiometric data.

Moore, R. K.; Eckerman, J.; Meneghini, R.; Atlas, D.; Boerner, W. M.; Cherry, S.; Clark, J. F.; Doviak, R. J.; Goldhirsh, J.; Lhermitte, R. M.

1981-01-01

187

Adaptive power-managed FMCW emitter detection performance against low-RCS ships  

Microsoft Academic Search

The design of a modern 9.3 GHz homodyne triangular-FMCW emitter for detection of low radar cross section (RCS) ships is described. Both searchand track-mode processing are described including a description of transmit and receive waveforms. Tradeoffs in emitter design are examined as a function of the modulation bandwidth. To predict target detection capability, clutter and target models are developed as

P. E. Pace

2001-01-01

188

Vacuum Rabi spectra of a single quantum emitter  

E-print Network

We report the observation of the vacuum Rabi splitting of a single quantum emitter by measuring its direct spontaneous emission into free space. We used a semiconductor quantum dot inside a photonic crystal nanocavity, in conjunction with an appropriate cavity design and filtering with a polarizer and an aperture, enabling the extraction of the inherently-weak emitter's signal. The emitter's vacuum Rabi spectra exhibit clear differences to those measured by detecting the cavity photon leakage. Moreover, we observed an asymmetric vacuum Rabi spectrum induced by interference between the emitter and cavity detection channels. Our observations lay the groundwork for accessing various cavity quantum electrodynamics phenomena that manifest themselves only in the emitter's direct spontaneous emission.

Ota, Yasutomo; Kumagai, Naoto; Iwamoto, Satoshi; Arakawa, Yasuhiko

2015-01-01

189

Vacuum Rabi spectra of a single quantum emitter  

E-print Network

We report the observation of the vacuum Rabi splitting of a single quantum emitter by measuring its direct spontaneous emission into free space. We used a semiconductor quantum dot inside a photonic crystal nanocavity, in conjunction with an appropriate cavity design and filtering with a polarizer and an aperture, enabling the extraction of the inherently-weak emitter's signal. The emitter's vacuum Rabi spectra exhibit clear differences to those measured by detecting the cavity photon leakage. Moreover, we observed an asymmetric vacuum Rabi spectrum induced by interference between the emitter and cavity detection channels. Our observations lay the groundwork for accessing various cavity quantum electrodynamics phenomena that manifest themselves only in the emitter's direct spontaneous emission.

Yasutomo Ota; Ryuichi Ohta; Naoto Kumagai; Satoshi Iwamoto; Yasuhiko Arakawa

2015-03-06

190

FACET Emittance Growth  

SciTech Connect

FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration. The FACET beamline consists of a chicane and final focus system to compress the 23 GeV, 3.2 nC electron bunches to {approx}20 {micro}m long and {approx}10 {micro}m wide. Simulations of the FACET beamline indicate the short-duration and large, 1.5% rms energy spread beams may suffer a factor of four emittance growth from a combination of chromaticity, incoherent synchrotron radiation (ISR), and coherent synchrotron radiation (CSR). Emittance growth is directly correlated to head erosion in plasma wakefield acceleration and is a limiting factor in single stage performance. Studies of the geometric, CSR, and ISR components are presented. Numerical calculation of the rms emittance can be overwhelmed by long tails in the simulated phase space distributions; more useful definitions of emittance are given. A complete simulation of the beamline is presented as well, which agrees with design specifications.

Frederico, J; Hogan, M.J.; Nosochkov, Y.; Litos, M.D.; Raubenheimer, T.; /SLAC

2011-04-05

191

A Special-Purpose Digital Radar Simulation and Performance Prediction Model  

Microsoft Academic Search

A special-purpose radar model has been developed to provide interim capability in the evaluation of Army radar performance. This irterim model is designed to be used pending development of the radar scoring facility and will be replaced by the empirical prediction model developed from the radar scoring facility. The radar model has three basic sections: (1) cross section and signal

Merle E. Parmer

1968-01-01

192

Middle Atmosphere Program. Handbook for MAP. Volume 30: International School on Atmospheric Radar  

NASA Technical Reports Server (NTRS)

Broad, tutorial coverage is given to the technical and scientific aspects of mesosphere stratosphere troposphere (MST) meteorological radar systems. Control issues, signal processing, atmospheric waves, the historical aspects of radar atmospheric dynamics, incoherent scatter radars, radar echoes, radar targets, and gravity waves are among the topics covered.

Fukao, Shoichiro (editor)

1989-01-01

193

A mathematical observation on synthetic aperture radar  

NASA Astrophysics Data System (ADS)

A general synthetic aperture radar (SAR) signal model is derived based on the Maxwells equation, and three numerical simulations are analyzed and discussed. With this signal model, compressive sensing is applied to get a better image.

Cao, Yufeng; Li, Shuxia; Lopez, Juan; Martinez, Alex; Qiao, Zhijun

2013-05-01

194

GPU Performance Comparison for Accelerated Radar Data Processing  

Microsoft Academic Search

Radar is a data-intensive measurement technique often requiring significant processing to make full use of the received signal. However, computing capacity is limited at remote or mobile radar installations thereby limiting radar data products used for real-time decisions. We used graphics processing units (GPUs) to accelerate processing of high resolution phase-coded radar data from the Modular UHF Ionosphere Radar (MUIR)

C. T. Fallen; B. V. C. Bellamy; G. B. Newby; B. J. Watkins

2011-01-01

195

Effect of Temperature Gradient on Thick Film Selective Emitter Emittance  

NASA Technical Reports Server (NTRS)

A temperature gradient across a thick (greater than or equal to .1 mm) film selective emitter will produce a significant reduction in the spectral emittance from the no temperature gradient case. Thick film selective emitters of rare earth doped host materials such as yttrium-aluminum-garnet (YAG) are examples where temperature gradient effects are important. In this paper a model is developed for the spectral emittance assuming a linear temperature gradient across the film. Results of the model indicate that temperature gradients will result in reductions the order of 20% or more in the spectral emittance.

Chubb, Donald L.; Good, Brian S.; Clark, Eric B.; Chen, Zheng

1997-01-01

196

The VHF experimental radar LARA. A long-wavelength radar for helicopter detection  

NASA Astrophysics Data System (ADS)

The application of a 63 MHz VHF-radar for the detection of helicopters was investigated. Radars at low frequency allow use of diffraction effects for target detection thereby extending the range beyond the horizon. Simulation calculations show that in the VHF-range a target echo can still be measured, in contrast with the S-band where an echo is no longer present. The backscatter cross section of helicopters was deduced. The emitter and receiver system of the experimental radar are described. The radar operates at 62.4 MHz and at 213 MHz (in pulse operation). It can unequivocally detect targets up to a distance of 6 km with a resolution of 60 m. The VHF radars are especially advantageous for the detection and identification of hovering helicopters.

Kuschel, H.

1987-04-01

197

Imaging synthetic aperture radar  

DOEpatents

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

Burns, Bryan L. (Tijeras, NM); Cordaro, J. Thomas (Albuquerque, NM)

1997-01-01

198

Metamaterials enable chiral-selective enhancement of two-photon luminescence from quantum emitters.  

PubMed

The amplification of chirally modified, non-linear signals from quantum emitters is demonstrated by manipulating the geometric chirality of resonant plasmonic nanostructures. The chiral center of the metamaterial is opened and emitters occupy this light-confining and chirally sensitive region. Non-linear emission signals are enhanced by 40× that of the emitters not embedded in the metamaterial and display a 3× contrast for the opposite circular polarization. PMID:25533019

Rodrigues, Sean P; Cui, Yonghao; Lan, Shoufeng; Kang, Lei; Cai, Wenshan

2015-02-01

199

Tracking system for photon-counting laser radar  

E-print Network

The purpose of this thesis is to build the tracking system for a photon-counting laser radar specifically a laser radar that has the ability to perform direct and coherent detection measurement at low signal levels with ...

Chang, Joshua TsuKang

2007-01-01

200

Coherent Multilateral Radar Processing for Precise Target Geolocation  

E-print Network

This paper analyzes the target geolocation performance of coherent processing of target signals observed by several radar receivers in a multilateral configuration. Each radar sensor is designed with a sufficient bandwidth ...

Jao, Jen King

201

Rare Earth Garnet Selective Emitter  

NASA Technical Reports Server (NTRS)

Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approx. = 0.75, sup 4)|(sub 15/2) - (sup 4)|(sub 13/2),for Er-YAG and epsilon(sub lambda) approx. = 0.65, (sup 5)|(sub 7) - (sup 5)|(sub 8) for Ho-YAG) at 1500 K. In addition, low out-of-band spectral emittance, epsilon(sub lambda) less than 0.2, suggest these materials would be excellent candidates for high efficiency selective emitters in thermophotovoltaic (TPV) systems operating at moderate temperatures (1200-1500 K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. Selective emitters in the near IR are of special interest for thermophotovoltaic (TPV) energy conversion. The most promising solid selective emitters for use in a TPV system are rare earth oxides. Early spectral emittance work on rare earth oxides showed strong emission bands in the infrared (0.9 - 3 microns). However, the emittance outside the emission band was also significant and the efficiency of these emitters was low. Recent improvements in efficiency have been made with emitters fabricated from fine (5 - 10 microns) rare earth oxide fibers similar to the Welsbach mantle used in gas lanterns. However, the rare earth garnet emitters are more rugged than the mantle type emitters. A thin film selective emitter on a low emissivity substrate such as gold, platinum etc., is rugged and easily adapted to a wide variety of thermal sources. The garnet structure and its many subgroups have been successfully used as hosts for rare earth ions, introduced as substitutional impurities, in the development of solid state laser crystals. Doping, dependent on the particular ion and crystal structure, may be as high as 100 at. % (complete substitution of yttrium ion with the rare earth ion). These materials have high melting points, 1940 C for YAG (Yttrium Aluminum Garnet), and low emissivity in the near infrared making them excellent candidates for a thin film selective emitter. As previously stated, the spectral emittance of a rare earth emitter is characterized by one or more well defined emission bands. Outside the emission band the emittance(absorptance) is much lower. Therefore, it is expected that emission outside the band for a thin film selective emitter will be dominated by the emitter substrate. For an efficient emitter (power in the emission band/total emitted power) the substrate must have low emittance, epsilon(sub S). This paper presents normal spectral emittance, epsilon(sub lambda), measurements of holmium(Ho) and erbium (Er) doped YAG thin film selective emitters at (1500 K), and compares those results with the theoretical spectral emittance.

Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

1994-01-01

202

All-digital radar architecture  

NASA Astrophysics Data System (ADS)

All digital radar architecture requires exclude mechanical scan system. The phase antenna array is necessarily large because the array elements must be co-located with very precise dimensions and will need high accuracy phase processing system for aggregate and distribute T/R modules data to/from antenna elements. Even phase array cannot provide wide field of view. New nature inspired all digital radar architecture proposed. The fly's eye consists of multiple angularly spaced sensors giving the fly simultaneously thee wide-area visual coverage it needs to detect and avoid the threats around him. Fly eye radar antenna array consist multiple directional antennas loose distributed along perimeter of ground vehicle or aircraft and coupled with receiving/transmitting front end modules connected by digital interface to central processor. Non-steering antenna array allows creating all-digital radar with extreme flexible architecture. Fly eye radar architecture provides wide possibility of digital modulation and different waveform generation. Simultaneous correlation and integration of thousands signals per second from each point of surveillance area allows not only detecting of low level signals ((low profile targets), but help to recognize and classify signals (targets) by using diversity signals, polarization modulation and intelligent processing. Proposed all digital radar architecture with distributed directional antenna array can provide a 3D space vector to the jammer by verification direction of arrival for signals sources and as result jam/spoof protection not only for radar systems, but for communication systems and any navigation constellation system, for both encrypted or unencrypted signals, for not limited number or close positioned jammers.

Molchanov, Pavlo A.

2014-10-01

203

An Acoustic / Radar System for Automated Detection, Localization, and Classification of  

E-print Network

1 An Acoustic / Radar System for Automated Detection, Localization, and Classification of Birds signal processing and classification DeTect, Inc. ­Bird Detection Radar, signal processing, radar data SPVA D/C/L CRH D/C/L Radar D/C/L ESM D/C/L IR D/C/L Shipboard Organic Sensors UAV Sensors Video D

Maher, Robert C.

204

Radar transponder operation with compensation for distortion due to amplitude modulation  

SciTech Connect

In radar transponder operation, a variably delayed gating signal is used to gate a received radar pulse and thereby produce a corresponding gated radar pulse for transmission back to the source of the received radar pulse. This compensates for signal distortion due to amplitude modulation on the retransmitted pulse.

Ormesher, Richard C. (Albuquerque, NM); Tise, Bertice L. (Albuquerque, NM); Axline, Jr., Robert M. (Albuquerque, NM)

2011-01-04

205

Powerful ultrawideband rf emitters: status and challenges  

NASA Astrophysics Data System (ADS)

Ultra-wideband emitters are of interest for a variety of potential applications that range from radar transmitters to communications applications. This technology is of current interest to the USAF Phillips Laboratory where theoretical and experimental efforts have been underway for a number of years. Research into the production of ultra-wideband sources at the Phillips Laboratory has been accomplished along several different technology lines. The approaches include three main thrusts: 1) very powerful hydrogen spark gap pulsers, 2) compact hydrogen gas switches in conjunction with high gain ultra-wideband antennas and, 3) solid state switched array antennas. This paper reviews the progress-to-date along these lines and identifies some pacing research obastacles that limit further improvements.

Agee, Forrest J.; Scholfield, David W.; Prather, William D.; Burger, Jeffrey W.

1995-09-01

206

A Study of Electrospray Ionization Emitters with Differing Geometries with Respect to Flow Rate and Electrospray Voltage  

NASA Astrophysics Data System (ADS)

The performance of several electrospray ionization emitters with different orifice inside diameters (i.d.s), geometries, and materials are compared. The sample solution is delivered by pressure driven flow, and the electrospray ionization voltage and flow rate are varied systematically for each emitter investigated, while the signal intensity of a standard is measured. The emitters investigated include a series of emitters with a tapered outside diameters (o.d.) and unaltered i.d.s, a series of emitters with tapered o.d.s and i.d.s, an emitter with a monolithic frit and a tapered o.d., and an emitter fabricated from polypropylene. The results show that for the externally etched emitters, signal was nearly independent of i.d. and better ion utilization was achieved at lower flow rates. Furthermore, emitters with a 50 ?m i.d. and an etched o.d. produced about 1.5 times more signal than etched emitters with smaller i.d.s and about 3.5 times more signal than emitters with tapered inner and outer dimensions. Additionally, the work presented here has important implications for applications in which maximizing signal intensity and reducing frictional resistance to flow are necessary. Overall, the work provides an initial assessment of the critical parameters that contribute to maximizing the signal for electrospray ionization sources interfaced with pressure driven flows.

Reschke, Brent R.; Timperman, Aaron T.

2011-12-01

207

Rare earth garnet selective emitter  

NASA Technical Reports Server (NTRS)

Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approximately equal to 0.74, ((4)l(sub 15/2)) - ( (4)l(sub13/2)), for Er-YAG and epsilon(sub lambda) approximately equal to 0.65, ((5)l(sub 7))-((5)l(sub 8)) for Ho-YAG) at excellent candidates for high efficiency selective emitters in the thermophotovoltaics (TPV) systems operating at moderate temperatures (1200-1500K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. This paper presents normal spectral emittance, epsilon(sub lambda), measurements of holmium (Ho), and erbium (Er) doped YAG thin film selective emitters at 1500 K, and compares those results with the theoretical spectral emittance.

Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

1994-01-01

208

Influences of weather phenomena on automotive laser radar systems  

NASA Astrophysics Data System (ADS)

Laser radar (lidar) sensors provide outstanding angular resolution along with highly accurate range measurements and thus they were proposed as a part of a high performance perception system for advanced driver assistant functions. Based on optical signal transmission and reception, laser radar systems are influenced by weather phenomena. This work provides an overview on the different physical principles responsible for laser radar signal disturbance and theoretical investigations for estimation of their influence. Finally, the transmission models are applied for signal generation in a newly developed laser radar target simulator providing - to our knowledge - worldwide first HIL test capability for automotive laser radar systems.

Rasshofer, R. H.; Spies, M.; Spies, H.

2011-07-01

209

Monolithic multinozzle emitters for nanoelectrospray mass spectrometry  

DOEpatents

Novel and significantly simplified procedures for fabrication of fully integrated nanoelectrospray emitters have been described. For nanofabricated monolithic multinozzle emitters (NM.sup.2 emitters), a bottom up approach using silicon nanowires on a silicon sliver is used. For microfabricated monolithic multinozzle emitters (M.sup.3 emitters), a top down approach using MEMS techniques on silicon wafers is used. The emitters have performance comparable to that of commercially-available silica capillary emitters for nanoelectrospray mass spectrometry.

Wang, Daojing (Daly City, CA); Yang, Peidong (Kensington, CA); Kim, Woong (Seoul, KR); Fan, Rong (Pasadena, CA)

2011-09-20

210

Radar range measurements in the atmosphere.  

SciTech Connect

The earth's atmosphere affects the velocity of propagation of microwave signals. This imparts a range error to radar range measurements that assume the typical simplistic model for propagation velocity. This range error is a function of atmospheric constituents, such as water vapor, as well as the geometry of the radar data collection, notably altitude and range. Models are presented for calculating atmospheric effects on radar range measurements, and compared against more elaborate atmospheric models.

Doerry, Armin Walter

2013-02-01

211

MIMO Radar Waveform Constraints for GMTI  

Microsoft Academic Search

Ground moving-target indication (GMTI) provides both an opportunity and challenge for coherent multiple-input multiple-output (MIMO) radar. MIMO techniques can improve a radar's angle estimation and the minimum detectable velocity (MDV) for a target. However, the challenge of clutter mitigation places significant constraints on MIMO radar waveforms. In this paper, the loss of target return because of clutter mitigation (signal-to-noise ratio

K. W. Forsythe; D. W. Bliss

2010-01-01

212

Survey of Chinese radars  

Microsoft Academic Search

Open information on about 200 Chinese radars including earlier radars is now available. By number of model types China is an important radar country. This Chinese radar survey paper shows that Chinese radars cover a wide spectrum of civilian and military applications. Chinese civilian radars include air-borne weather avoidance\\/navigation, air traffic control (ASR, ARSR, GCA, SSR), harbor surveillance, industrial applications,

S. L. Johnston

1995-01-01

213

Electrochemical formation of field emitters  

DOEpatents

Electrochemical formation of field emitters, particularly useful in the fabrication of flat panel displays is disclosed. The fabrication involves field emitting points in a gated field emitter structure. Metal field emitters are formed by electroplating and the shape of the formed emitter is controlled by the potential imposed on the gate as well as on a separate counter electrode. This allows sharp emitters to be formed in a more inexpensive and manufacturable process than vacuum deposition processes used at present. The fabrication process involves etching of the gate metal and the dielectric layer down to the resistor layer, and then electroplating the etched area and forming an electroplated emitter point in the etched area. 12 figs.

Bernhardt, A.F.

1999-03-16

214

Amorphous-diamond electron emitter  

DOEpatents

An electron emitter comprising a textured silicon wafer overcoated with a thin (200 .ANG.) layer of nitrogen-doped, amorphous-diamond (a:D-N), which lowers the field below 20 volts/micrometer have been demonstrated using this emitter compared to uncoated or diamond coated emitters wherein the emission is at fields of nearly 60 volts/micrometer. The silicon/nitrogen-doped, amorphous-diamond (Si/a:D-N) emitter may be produced by overcoating a textured silicon wafer with amorphous-diamond (a:D) in a nitrogen atmosphere using a filtered cathodic-arc system. The enhanced performance of the Si/a:D-N emitter lowers the voltages required to the point where field-emission displays are practical. Thus, this emitter can be used, for example, in flat-panel emission displays (FEDs), and cold-cathode vacuum electronics.

Falabella, Steven (Livermore, CA)

2001-01-01

215

High resolution radar imaging  

NASA Astrophysics Data System (ADS)

The goal of this project is to formulate and investigate new approaches for forming images of radar targets from spotlight-mode, delay-doppler measurements. These measurements could be acquired with a high-resolution radar-imaging system operating with an optical-or radio-frequency carrier. Two approaches are under study. The first is motivated by an image-reconstruction algorithm used in radionuclide imaging called the confidence-weighted algorithm; here, we will refer to this approach as the chirp-rate modulation approach. The second approach is based on more fundamental principles which starts with a mathematical model that accurately describes the physics of an imaging radar-system and then uses statistical-estimation theory with this model to derive processing algorithms; we will refer to this as the estimation-theory approach. Progress during this reporting period has been made on: (1) extending the estimation-theory approach to include a constraint on input signal-to-noise ratio; (2) extending the estimation-theory approach to include a sieve constraint for stabilizing image estimates, (3) extending the estimation-theory approach to include a specular or glint component in the radar-echo data; (4) analyzing the performance of the estimation-theory approach through computer simulations; and (5) modifying the chirp-rate modulation approach through the introduction of the Wigner-Ville distribution. A patent was awarded associated with the chirp-rate modulation approach.

Snyder, Donald L.

1988-11-01

216

Large phased-array radars  

SciTech Connect

Large phased-array radars can play a very important part in arms control. They can be used to determine the number of RVs being deployed, the type of targeting of the RVs (the same or different targets), the shape of the deployed objects, and possibly the weight and yields of the deployed RVs. They can provide this information at night as well as during the day and during rain and cloud covered conditions. The radar can be on the ground, on a ship, in an airplane, or space-borne. Airborne and space-borne radars can provide high resolution map images of the ground for reconnaissance, of anti-ballistic missile (ABM) ground radar installations, missile launch sites, and tactical targets such as trucks and tanks. The large ground based radars can have microwave carrier frequencies or be at HF (high frequency). For a ground-based HF radar the signal is reflected off the ionosphere so as to provide over-the-horizon (OTH) viewing of targets. OTH radars can potentially be used to monitor stealth targets and missile traffic.

Brookner, D.E.

1988-12-15

217

Modern radar: Theory, operation and maintenance \\/2nd edition  

Microsoft Academic Search

A compendium on radar systems and theory is presented. The development of the magnetron and the klystron is reviewed along with the methods used to solve the original radar problems. The early display devices are surveyed with a view to their ongoing evolution. The pulse, Doppler, CW, and pulse-Doppler radar systems are detailed. Target reflectivity, pulse calculations, Doppler clutter, signal

E. L. Safford Jr.

1981-01-01

218

33 CFR 118.120 - Radar reflectors and racons.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Radar reflectors and racons. 118.120 Section...LIGHTING AND OTHER SIGNALS § 118.120 Radar reflectors and racons. The District...require or authorize the installation of radar reflectors and racons on bridge...

2011-07-01

219

CHARACTERIZATION OF A COOPERATIVE TARGET FOR GROUND-PENETRATING RADAR  

E-print Network

CHARACTERIZATION OF A COOPERATIVE TARGET FOR GROUND- PENETRATING RADAR Christopher T. Allen, Kun Shi, and Richard G. Plumb Radar Systems and Remote Sensing Laboratory, The University of Kansas, 2291 been developed to en- hance the ground-penetrating radar (GPR) signal-to- clutter ratio for buried man

Kansas, University of

220

33 CFR 118.120 - Radar reflectors and racons.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Radar reflectors and racons. 118.120 Section...LIGHTING AND OTHER SIGNALS § 118.120 Radar reflectors and racons. The District...require or authorize the installation of radar reflectors and racons on bridge...

2013-07-01

221

33 CFR 118.120 - Radar reflectors and racons.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 2014-07-01 false Radar reflectors and racons. 118.120 Section...LIGHTING AND OTHER SIGNALS § 118.120 Radar reflectors and racons. The District...require or authorize the installation of radar reflectors and racons on bridge...

2014-07-01

222

33 CFR 118.120 - Radar reflectors and racons.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Radar reflectors and racons. 118.120 Section...LIGHTING AND OTHER SIGNALS § 118.120 Radar reflectors and racons. The District...require or authorize the installation of radar reflectors and racons on bridge...

2010-07-01

223

33 CFR 118.120 - Radar reflectors and racons.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Radar reflectors and racons. 118.120 Section...LIGHTING AND OTHER SIGNALS § 118.120 Radar reflectors and racons. The District...require or authorize the installation of radar reflectors and racons on bridge...

2012-07-01

224

Twin VHF radar for european space situation awareness system  

Microsoft Academic Search

The efficient space surveillance system in the current state of radar technology must be addressed in a cost-effective way. Consequently, a new twin VHF band radar concept with increased technical capabilities could partially take over these challenges. This article would like to draw the reader's attention to the potential benefits of VHF radar signal fusion, which can be extended for

Istvan Balajti

2012-01-01

225

Coherent multilateral radar processing for precise target geolocation  

Microsoft Academic Search

This paper analyzes the target geolocation performance of coherent processing of target signals observed by several radar receivers in a multilateral configuration. Each radar sensor is designed with a sufficient bandwidth to support good target range resolution but without the benefit of a narrow radar antenna beam for useful cross range measurement of the target position. The analysis results demonstrate

Jen King Jao

2006-01-01

226

A system model and inversion for synthetic aperture radar imaging  

Microsoft Academic Search

A system model and its corresponding inversion for synthetic aperture radar (SAR) imaging are presented. The system model incorporates the spherical nature of a radar's radiation pattern at far field. The inverse method based on this model performs a spatial Fourier transform (Doppler processing) on the recorded signals with respect to the available coordinates of a translational radar (SAR) or

Mehrdad Soumekh

1992-01-01

227

Classification of radar clutter in an air traffic control environment  

Microsoft Academic Search

The results of an experimental study aimed at the classification of radar clutter encountered on ground-based coherent scanning radar systems used for air traffic control are presented. The clutter signals of interest are primarily those due to birds and to clouds and weather systems. A historical perspective on the radar clutter classification problem is given, and related issues are discussed.

SIMON HAYKIN; WOLFGANG STEHWIEN; CONG DENG; PETER WEBER; RICHARD MANN

1991-01-01

228

Eliminating Doppler Effects in Synthetic-Aperture Radar Optical Processors  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

229

A satellite-based radar wind sensor  

NASA Technical Reports Server (NTRS)

The objective is to investigate the application of Doppler radar systems for global wind measurement. A model of the satellite-based radar wind sounder (RAWS) is discussed, and many critical problems in the designing process, such as the antenna scan pattern, tracking the Doppler shift caused by satellite motion, and backscattering of radar signals from different types of clouds, are discussed along with their computer simulations. In addition, algorithms for measuring mean frequency of radar echoes, such as the Fast Fourier Transform (FFT) estimator, the covariance estimator, and the estimators based on autoregressive models, are discussed. Monte Carlo computer simulations were used to compare the performance of these algorithms. Anti-alias methods are discussed for the FFT and the autoregressive methods. Several algorithms for reducing radar ambiguity were studied, such as random phase coding methods and staggered pulse repitition frequncy (PRF) methods. Computer simulations showed that these methods are not applicable to the RAWS because of the broad spectral widths of the radar echoes from clouds. A waveform modulation method using the concept of spread spectrum and correlation detection was developed to solve the radar ambiguity. Radar ambiguity functions were used to analyze the effective signal-to-noise ratios for the waveform modulation method. The results showed that, with suitable bandwidth product and modulation of the waveform, this method can achieve the desired maximum range and maximum frequency of the radar system.

Xin, Weizhuang

1991-01-01

230

First radar echoes from cumulus clouds  

NASA Technical Reports Server (NTRS)

In attempting to use centimeter-wavelength radars to investigate the early stage of precipitation formation in clouds, 'mantle echoes' are rediscovered and shown to come mostly from scattering by small-scale variations in refractive index, a Bragg kind of scattering mechanism. This limits the usefulness of single-wavelength radar for studies of hydrometeor growth, according to data on summer cumulus clouds in North Dakota, Hawaii, and Florida, to values of reflectivity factor above about 10 dBZe with 10-cm radar, 0 dBZe with 5-cm radar, and -10 dBZe with 3-cm radar. These are limits at or above which the backscattered radar signal from the kinds of clouds observed can be assumed to be almost entirely from hydrometeors or (rarely) other particulate material such as insects. Dual-wavelength radar data can provide the desired information about hydrometeors at very low reflectivity levels if assumptions can be made about the inhomogeneities responsible for the Bragg scattering. The Bragg scattering signal itself probably will be a useful way to probe inhomogeneities one-half the radar wavelength in scale for studying cloud entrainment and mixing processes. However, this use is possible only before scattering from hydrometeors dominates the radar return.

Knight, Charles A.; Miller, L. J.

1993-01-01

231

Electromagnetic interference impact of the proposed emitters for the High Frequency Active Auroral Research Program (HAARP). Interim report  

SciTech Connect

The proposed HAARP emitters at the Gakona (Alaska) preferred site and at the Clear AFS (Alaska) alternative site are the Ionospheric Research Instrument (IRI), the Incoherent Scatter Radar (ISR), and the Vertical Incidence Sounder(VIS). The electromagnetic interference (EMI) impact of those emitters on receiving systems in the vicinity of the sites is estimated in this study. The results are intended for use as an input to the Air Force Environmental Impact Statement as part of the Environmental Impact Analysis Process.

Robertshaw, G.A.; Snyder, A.L.; Weiner, M.M.

1993-05-14

232

Principles of inverse synthetic aperture radar \\/ISAR\\/ imaging  

Microsoft Academic Search

Inverse synthetic aperture radar (ISAR) imaging principles, general motion compensation, cross-range scaling considerations and preliminary images are presented. Two-dimensional images of radar targets are extracted from a stationary radar, and ISAR target images are developed by sensing the target translational and rotational motion relative to the radar platform, and cohesively processing the signals. High-range resolution is achieved by wideband pulse

M. J. Prickett; C. C. Chen

1980-01-01

233

Fly eye radar or micro-radar sensor technology  

NASA Astrophysics Data System (ADS)

To compensate for its eye's inability to point its eye at a target, the fly's eye consists of multiple angularly spaced sensors giving the fly the wide-area visual coverage it needs to detect and avoid the threats around him. Based on a similar concept a revolutionary new micro-radar sensor technology is proposed for detecting and tracking ground and/or airborne low profile low altitude targets in harsh urban environments. Distributed along a border or around a protected object (military facility and buildings, camp, stadium) small size, low power unattended radar sensors can be used for target detection and tracking, threat warning, pre-shot sniper protection and provides effective support for homeland security. In addition it can provide 3D recognition and targets classification due to its use of five orders more pulses than any scanning radar to each space point, by using few points of view, diversity signals and intelligent processing. The application of an array of directional antennas eliminates the need for a mechanical scanning antenna or phase processor. It radically decreases radar size and increases bearing accuracy several folds. The proposed micro-radar sensors can be easy connected to one or several operators by point-to-point invisible protected communication. The directional antennas have higher gain, can be multi-frequency and connected to a multi-functional network. Fly eye micro-radars are inexpensive, can be expendable and will reduce cost of defense.

Molchanov, Pavlo; Asmolova, Olga

2014-05-01

234

Radars in space  

NASA Technical Reports Server (NTRS)

The capabilities of active microwave devices operating from space (typically, radar, scatterometers, interferometers, and altimeters) are discussed. General radar parameters and basic radar principles are explained. Applications of these parameters and principles are also explained. Trends in space radar technology, and where space radars and active microwave sensors in orbit are going are discussed.

Delnore, Victor E.

1990-01-01

235

Securing radars using secure wireless sensor networking  

NASA Astrophysics Data System (ADS)

Radar sensors can be viewed as a limited wireless sensor network consisting of radar transmitter nodes, target nodes, and radar receiver nodes. The radar transmitter node sends a communication signal to the target node which then reflects it in a known pattern to the radar receiver nodes. This type of wireless sensor network is susceptible to the same types of attacks as a traditional wireless sensor network, but there is less opportunity for defense. The target nodes in the network are unable to validate the return signal, and they are often uncooperative. This leads to ample opportunities for spoofing and man-in-the-middle attacks. This paper explores some of the fundamental techniques that can be used against a limited wireless network system as well as explores the techniques that can be used to counter them.

Tahmoush, David

2014-06-01

236

CIE 1991 International Conference on Radar (CICR-91), Beijing, China, Oct. 22-24, 1991, Proceedings  

NASA Astrophysics Data System (ADS)

The present volume on radar discusses a modern perspective on radar signal processing, a historical survey on airborne early warning, array pattern and target parameter estimation for distributed array radar, and a review of surface surveillance radars. Attention is given to new concepts of spaceborne surveillance radar, UHF Doppler wind-profiling radar and performance analyses, a low-angle tracking method for tactical monopulse radars, and a laser radar for the detection of cables and other hazardous obstacles. Topics addressed include real-time multifunction radar simulation, new estimators of probability tails for radar application, an advanced low-altitude search radar, and beam spacing optimization for a surveillance phased array radar. Also discussed are broadband aspects of a triple-patch antenna as an array element, an effective way to analyze broadband radomes, selective devices on magnetostatic surface waves, and the orthogonality algorithm in adaptive arrays.

Li, Nengjing; Zhou, Siyong

237

Understanding the relationships between radar response patterns and the bio- and geophysical parameters of urban areas  

Microsoft Academic Search

This paper reviews the current understanding of the relationships between radar response patterns and the bio- and geophysical parameters of urban areas. Specifically, it examines the effects of radar system, ground target, and environmental factors on the intensity and pattern of radar returns from urban features. System parameters considered include radar signal wavelength, polarization, incident angle, and look direction. Ground

Zong-Guo Xia; Floyd M. Henderson

1997-01-01

238

Natural oil seep detection in the Santa Barbara Channel, California, with Shuttle Imaging Radar  

Microsoft Academic Search

Natural submarine oil seeps in the Santa Barbara Channel, California, were detected by the first Shuttle Imaging Radar (SIR-A). Oil slicks on the ocean are seen in radar imagery as areas of decreased radar signal return that result from a damping of surface roughness. Orbital radar imagery shows promise as an effective and efficient means of mapping submarine oil seeps

John E. Estes; Robert E. Crippen; Jeffrey L. Star

1985-01-01

239

Progress In Electromagnetics Research, PIER 58, 301317, 2006 DETECTION AND LOCALIZATION OF RF RADAR  

E-print Network

RADAR PULSES IN NOISE ENVIRONMENTS USING WAVELET PACKET TRANSFORM AND HIGHER ORDER STATISTICS O. A. M problems in radar systems. Radar performance can be improved by increasing the receiver output signal. In this paper an algorithm is described for extracting and localizing an RF radar pulse from a noisy background

Elsherbeni, Atef Z.

240

Exploring the limits of single emitter detection in fluorescence and extinction  

E-print Network

We present an experimental comparison and a theoretical analysis of the signal-to-noise ratios in fluorescence and extinction spectroscopy of a single emitter. We show that extinction measurements can be advantageous if the emitter is weakly excited. Furthermore, we discuss the potential of this method for the detection and spectroscopy of weakly emitting systems such as rare earth ions.

Gert Wrigge; Jaesuk Hwang; Ilja Gerhardt; Gert Zumofen; Vahid Sandoghdar

2008-08-25

241

Porous Ion Emitters: A New Type of Thermal Ion Emitter  

SciTech Connect

A new type of porous refractory material has been developed as a thermal ionization emitter that is an improvement over both direct filament and resin bead loading. The porous ion emitter is sintered onto the center of a conventional thermal ionization filament and an aqueous solution containing the sample wicked into this emitter. Application of the porous ion emitter to uranium is demonstrated to provide a utilization efficiency ranging between 1% to 2% across a sample size range of 0.2 – 10 pg, better than that achieved from resin beads and much better than that achieved with direct loading onto a filament. The technique improves sensitivity and reduces the chance of losing a high value sample by eliminating microscopic manipulation of a single resin bead containing an entire sample.

Matthew G. Watrous; James E. Delmore; Mark L. Stone

2010-10-01

242

Emittance and Phase Space Exchange  

SciTech Connect

Alternative chicane-type beam lines are proposed for exact emittance exchange between horizontal phase space (x; x{prime}) and longitudinal phase space (z; {delta}). Methods to achieve exact phase space exchanges, i.e. mapping x to z, x{prime} to {delta}, z to x and {delta} to x{prime} are suggested. Methods to mitigate the thick-lens effect of the transverse cavity on emittance exchange are discussed. Some applications of the phase space exchanger and the feasibility of an emittance exchange experiment with the proposed chicane-type beam line at SLAC are discussed.

Xiang, Dao; Chao, Alex; /SLAC

2011-08-19

243

Weather Radar Fundamentals  

NSDL National Science Digital Library

This 2-hour module presents the fundamental principles of Doppler weather radar operation and how to interpret common weather phenomena using radar imagery. This is accomplished via conceptual animations and many interactive radar examples in which the user can practice interpreting both radar reflectivity and radar velocity imagery. Although intended as an accelerated introduction to understanding and using basic Doppler weather radar products, the module can also serve as an excellent refresher for more experienced users.

2014-09-14

244

Field-emitter arrays for vacuum microelectronics  

Microsoft Academic Search

An ongoing program on microfabricated field-emitter arrays has produced a gated field-emitter tip structure with submicrometer dimensions and techniques for fabricating emitter arrays with tip packaging densities of up to 1.5×107 tips\\/cm2. Arrays have been fabricated over areas varying from a few micrometers up to 13 cm in diameter. Very small overall emitter size, materials selection, and rigorous emitter-tip processing

C. A. Spindt; C. E. Holland; A. Rosengreen; I. Brodie

1991-01-01

245

Radar sensing of petroleum seepage gases  

NASA Astrophysics Data System (ADS)

Simple X-band radars have been used by a number of commercial exploration companies since 1972 in the search for gas and oil deposits. Uncertainty and controversy over the physical mechanism involved in the radar sensing of gas and oil led to the April/May 1992 radar investigation conducted by NRL. A low power X-band radar was used by NRL to acquire experimental data in Texas. The attributes of return signals observed over producing and prospective oil fields were found to have a unique set of characteristics which included the following: return signals were from weak, distributed targets: simultaneous amplitude and range variations were observed (10 dB or more in amplitude and +/- 60 ft in range) within time intervals of 1/3rd second and at ranges of from 500 to 2,000 ft, and at elevation angles of less than + 1 deg. The range and amplitude varying radar returns were suppressed by rain and/or a wet earth. Also during a single period of 24 hour observation, the varying signals disappeared during a period of high humidity (local night-time) and then re-appeared the next day when the relative humidity dropped below 50%. Radar returns from seepage gases heights greater than 25 feet as well as gas associated radar returns over cattle feed lots (methane and ammonia) were not confirmed.

Hemenway, Donald F.; Hansen, James P.; George, Eugene G.

1993-01-01

246

Data Acquisition System for Doppler Radar Vital-Sign Monitor  

Microsoft Academic Search

Automatic gain control (AGC) units increase the dynamic range of a system to compensate for the limited dynamic range of analog to digital converters. This problem is compounded in wireless systems in which large changes in signal strength are effects of a changing environment. These issues are evident in the direct-conversion Doppler radar vital- sign monitor. Utilizing microwave radar signals

Alexander M. Vergara; Victor M. Lubecke

2007-01-01

247

Considerations on data compression of synthetic aperture radar images  

Microsoft Academic Search

This paper describes some analytical results relative to the effectiveness of applying data compression techniques for efficient transmission of synthetic aperture radar (SAR) signals and images. A Rayleigh target model is assumed in the analysis. It is also assumed that all surface reflectivity information is of interest and needs to be transmitted. Spectral characteristics of radar echo signals and processed

C. Wu

1976-01-01

248

Future Trends in Automotive Radar \\/ Imaging Radar  

Microsoft Academic Search

There is a growing interest of car manufacturers in sensors monitoring the car's surrounding area in order to improve safety systems from mere crash survival to crash prediction or prevention by early detection of hazardous situations. Therefore radar sensors have been intensively investigated for many years. A large variety of radar based vehicular sensors have been developed. Narrow-beam radars are

J. Wenger

1998-01-01

249

RANGE RECURSIVE SPACE TIME ADAPTIVE PROCESSING (STAP) FOR MIMO AIRBORNE RADAR  

E-print Network

RANGE RECURSIVE SPACE TIME ADAPTIVE PROCESSING (STAP) FOR MIMO AIRBORNE RADAR Sylvie Marcos) of multi input multi output (MIMO) airborne radar signals involved in clutter rejection for the detection. INTRODUCTION Space time adaptive processing (STAP) of airborne radar signals received on an array of antennas

250

Joint UK/US Radar Program progress reports for period December 1--31, 1994  

SciTech Connect

Topics discussed in this report are current accomplishments in many functions to include: airborne RAR/SAR, radar data processor, ground based SAR signal processing workstation, static airborne radar, multi-aperture space-time array radar, radar field experiments, data analysis and detection theory, management, radar data analysis, modeling and analysis, current meter array, UCSB wave tank, stratified flow facility, Russian Institute of Applied Physics, and budget status.

Twogood, R.E.; Brase, J.M.; Mantrom, D.D.; Rino, C.; Chambers, D.H.; Robey, H.F.; Belyea, J.

1995-01-23

251

Modern radar: Theory, operation and maintenance /2nd edition/  

NASA Astrophysics Data System (ADS)

A compendium on radar systems and theory is presented. The development of the magnetron and the klystron is reviewed along with the methods used to solve the original radar problems. The early display devices are surveyed with a view to their ongoing evolution. The pulse, Doppler, CW, and pulse-Doppler radar systems are detailed. Target reflectivity, pulse calculations, Doppler clutter, signal processing, and bandwidth are discussed. The uses and basic components are examined of the radar systems utilized in military, intruder detection, avionics, aerospace, police, satellite, and guided missile applications. A coverage of radar frequency components, tracking systems, aircraft signatures, and receivers is provided.

Safford, E. L., Jr.

1981-02-01

252

Tangential velocity measurement using interferometric MTI radar  

DOEpatents

Radar systems use time delay measurements between a transmitted signal and its echo to calculate range to a target. Ranges that change with time cause a Doppler offset in phase and frequency of the echo. Consequently, the closing velocity between target and radar can be measured by measuring the Doppler offset of the echo. The closing velocity is also known as radial velocity, or line-of-sight velocity. Doppler frequency is measured in a pulse-Doppler radar as a linear phase shift over a set of radar pulses during some Coherent Processing Interval (CPI). An Interferometric Moving Target Indicator (MTI) radar can be used to measure the tangential velocity component of a moving target. Multiple baselines, along with the conventional radial velocity measurement, allow estimating the true 3-D velocity of a target.

Doerry, Armin W.; Mileshosky, Brian P.; Bickel, Douglas L.

2006-01-03

253

Radar Location Equipment Development Program: Phase I  

SciTech Connect

The work described in this report represents the first phase of a planned three-phase project designed to develop a radar system for monitoring waste canisters stored in a thick layer of bedded salt at the Waste Isolation Pilot Plant near Carlsbad, New Mexico. The canisters will be contained in holes drilled into the floor of the underground waste storage facility. It is hoped that these measurements can be made to accuracies of +-5 cm and +-2/sup 0/, respectively. The initial phase of this project was primarily a feasibility study. Its principal objective was to evaluate the potential effectiveness of the radar method in the planned canister monitoring application. Its scope included an investigation of the characteristics of radar signals backscattered from waste canisters, a test of preliminary data analysis methods, an assessment of the effects of salt and bentonite (a proposed backfill material) on the propagation of the radar signals, and a review of current ground-penetrating radar technology. A laboratory experiment was performed in which radar signals were backscattered from simulated waste canisters. The radar data were recorded by a digital data acquisition system and were subsequently analyzed by three different computer-based methods to extract estimates of canister location and tilt. Each of these methods yielded results that were accurate within a few centimeters in canister location and within 1/sup 0/ in canister tilt. Measurements were also made to determine the signal propagation velocities in salt and bentonite (actually a bentonite/sand mixture) and to estimate the signal attenuation rate in the bentonite. Finally, a product survey and a literature search were made to identify available ground-penetrating radar systems and alternative antenna designs that may be particularly suitable for this unique application. 10 refs., 21 figs., 4 tabs.

Sandness, G.A.; Davis, K.C.

1985-06-01

254

Architecture for a 1-GHz Digital RADAR  

NASA Technical Reports Server (NTRS)

An architecture for a Direct RF-digitization Type Digital Mode RADAR was developed at GSFC in 2008. Two variations of a basic architecture were developed for use on RADAR imaging missions using aircraft and spacecraft. Both systems can operate with a pulse repetition rate up to 10 MHz with 8 received RF samples per pulse repetition interval, or at up to 19 kHz with 4K received RF samples per pulse repetition interval. The first design describes a computer architecture for a Continuous Mode RADAR transceiver with a real-time signal processing and display architecture. The architecture can operate at a high pulse repetition rate without interruption for an infinite amount of time. The second design describes a smaller and less costly burst mode RADAR that can transceive high pulse repetition rate RF signals without interruption for up to 37 seconds. The burst-mode RADAR was designed to operate on an off-line signal processing paradigm. The temporal distribution of RF samples acquired and reported to the RADAR processor remains uniform and free of distortion in both proposed architectures. The majority of the RADAR's electronics is implemented in digital CMOS (complementary metal oxide semiconductor), and analog circuits are restricted to signal amplification operations and analog to digital conversion. An implementation of the proposed systems will create a 1-GHz, Direct RF-digitization Type, L-Band Digital RADAR--the highest band achievable for Nyquist Rate, Direct RF-digitization Systems that do not implement an electronic IF downsample stage (after the receiver signal amplification stage), using commercially available off-the-shelf integrated circuits.

Mallik, Udayan

2011-01-01

255

CESM: A new category of radar ECCM  

NASA Astrophysics Data System (ADS)

Radar ECCM techniques are well known. Heretofore the listed ECCM effects have generally been to counteract the effects of ECM. This approach is one of attempting to cure an illness, rather than preventing it. Modern ECM systems usually include an ESM receiver to detect the radar signal, identify it by its emission characteristics, assess its importance, select the proper ECM, and signal to initiate ECM. If the ESM receiver detection of the radar signal can be delayed/denied, or the identification be confused, either the wrong ECM may be applied, or delayed. The radar may thus not be confronted with timely, proper ECM. Radar operation may therefore be possible. This paper introduces and defines counter electronic support measures (CESM), a new category of radar ECCM. There are two principles of CESM - those which delay/deny ESM receiver detection, and those which confuse/impede signal identification. Illustrative examples of CESM techniques/operating techniques are given. It is shown that many CESM techniques may have multiple roles by impeding detection, impeding identification, and also diluting effects of ECM.

Johnston, Stephen L.

1995-02-01

256

Analog FIR Filter Used for Range-Optimal Pulsed Radar Applications  

E-print Network

Matched filter is one of the most critical block in radar applications. With different measured range and relative velocity of a target we will need different bandwidth of the matched filter to maximize the radar signal to noise ratio (SNR...

Su, Eric Chen

2014-08-13

257

Space Radar Image of Long Island Optical/Radar  

NASA Technical Reports Server (NTRS)

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

1994-01-01

258

Dual-polarization radar rainfall estimation  

NASA Astrophysics Data System (ADS)

Dual-polarization radar is a critical tool for weather research applications, including rainfall estimation, and is at the verge of being a key instrument for operational meteorologists. This new radar system is being integrated into radar networks around the world, including the planned upgrade of the U.S. National Weather Service Weather Surveillance Radar, 1988 Doppler radars. Dual polarization offers several advantages compared to single-polarization radar systems, including additional information about the size, shape, and orientation of hydrometeors. This information can be used to more accurately retrieve characteristics of the drop size distribution, identify types of hydrometeors, correct for signal loss (attenuation) in heavy precipitation, and more easily identify spurious echo scatterers. In addition to traditional backscatter measurements, differential propagation phase characteristics allow for rainfall estimation that is immune to absolute calibration of the radar system, attenuation effects, as well as partial beam blocking. By combining different radar measurements, rainfall retrieval algorithms have developed that minimize the error characteristics of the different rainfall estimators, while at the same time taking advantage of the data quality enhancements. Although dual-polarization techniques have been applied to S band and C band radar systems for several decades, polarization diversity at higher frequencies including X band are now widely available to the radar community. This chapter provides an overview of dual-polarization rainfall estimation applications that are typically utilized at X, C, and S bands. The concept of distinguishing basic and applied science issues and their impact on rainfall estimation is introduced. Various dual-polarization radar rainfall techniques are discussed, emphasizing the strengths and weaknesses of various estimators at different frequencies.

Cifelli, Robert; Chandrasekar, V.

259

Standard emitters (clocks) and calibrated standard emitters (clocks) in spaces with affine connections and metrics  

E-print Network

It is shown that the general belief that the frequency and the absolute value of the velocity of periodic signals sent by a standard emitter do not change on the world line of the emitter needs to be revised and new conditions for the existence of a calibrted standard emitter should be taken into account. The notions of a standard clock and of a calibrated standard clock are introduced in a space with affine connections and metrics. The variation of the velocity and of the frequency of a standard clock could be compared with the constant velocity and the constant frequency of a calibrated standard clock along the world line of the observer. This calibrated standard clock is transported by meand of a generalized Fermi-Walker transport along the same world line of the observer. Some remarks about the synchronization of standard clocks in spaces with affine connections and metrics are given. PACS numbers: 95.30.Sf; 04.90.+h; 04.20.Cv; 04.90.+e

Sawa Manoff

2005-05-12

260

Detecting and Mitigating Wind Turbine Clutter for Airspace Radar Systems  

PubMed Central

It is well recognized that a wind turbine has a large radar cross-section (RCS) and, due to the movement of the blades, the wind turbine will generate a Doppler frequency shift. This scattering behavior may cause severe interferences on existing radar systems including static ground-based radars and spaceborne or airborne radars. To resolve this problem, efficient techniques or algorithms should be developed to mitigate the effects of wind farms on radars. Herein, one transponder-based mitigation technique is presented. The transponder is not a new concept, which has been proposed for calibrating high-resolution imaging radars. It modulates the radar signal in a manner that the retransmitted signals can be separated from the scene echoes. As wind farms often occupy only a small area, mitigation processing in the whole radar operation will be redundant and cost inefficient. Hence, this paper uses a transponder to determine whether the radar is impacted by the wind farms. If so, the effects of wind farms are then mitigated with subsequent Kalman filtering or plot target extraction algorithms. Taking airborne synthetic aperture radar (SAR) and pulse Doppler radar as the examples, this paper provides the corresponding system configuration and processing algorithms. The effectiveness of the mitigation technique is validated by numerical simulation results. PMID:24385880

2013-01-01

261

Detecting and mitigating wind turbine clutter for airspace radar systems.  

PubMed

It is well recognized that a wind turbine has a large radar cross-section (RCS) and, due to the movement of the blades, the wind turbine will generate a Doppler frequency shift. This scattering behavior may cause severe interferences on existing radar systems including static ground-based radars and spaceborne or airborne radars. To resolve this problem, efficient techniques or algorithms should be developed to mitigate the effects of wind farms on radars. Herein, one transponder-based mitigation technique is presented. The transponder is not a new concept, which has been proposed for calibrating high-resolution imaging radars. It modulates the radar signal in a manner that the retransmitted signals can be separated from the scene echoes. As wind farms often occupy only a small area, mitigation processing in the whole radar operation will be redundant and cost inefficient. Hence, this paper uses a transponder to determine whether the radar is impacted by the wind farms. If so, the effects of wind farms are then mitigated with subsequent Kalman filtering or plot target extraction algorithms. Taking airborne synthetic aperture radar (SAR) and pulse Doppler radar as the examples, this paper provides the corresponding system configuration and processing algorithms. The effectiveness of the mitigation technique is validated by numerical simulation results. PMID:24385880

Wang, Wen-Qin

2013-01-01

262

Radar simulation program upgrade and algorithm development  

NASA Technical Reports Server (NTRS)

The NASA Radar Simulation Program is a comprehensive calculation of the expected output of an airborne coherent pulse Doppler radar system viewing a low level microburst along or near the approach path. Inputs to the program include the radar system parameters and data files that contain the characteristics of the microbursts to be simulated, the ground clutter map, and the discrete target data base which provides a simulation of the moving ground clutter. For each range bin, the simulation calculates the received signal amplitude level by integrating the product of the antenna gain pattern and the scattering source amplitude and phase of a spherical shell volume segment defined by the pulse width, radar range, and ground plane intersection. A series of in-phase and quadrature pulses are generated and stored for further processing if desired. In addition, various signal processing techniques are used to derive the simulated velocity and hazard measurements, and store them for use in plotting and display programs.

Britt, Charles L.

1991-01-01

263

Recent advances in radar polarimetry - Assessment of the historical development  

NASA Astrophysics Data System (ADS)

This introductory paper provides a succinct overview of the historical developments in radar polarimetry highlighting important contributions and including concise definitions and descriptions of the scattering matrix operations, and the polarimetric target (desired signal/image) versus clutter (undesired signal/image) optimization problems. A historical events table together with a list of pertinent references is provided together with a critical review on the validity of various polarization dependent approaches to radar target phenomenology. Specific results are not reported here, but will be the subject of other lectures on selected topics on fundamentals of radar polarimetry and its applications to high resolution polarimetric radar imaging.

Boerner, W.-M.

264

A high resolution multimode synthetic aperture radar  

NASA Astrophysics Data System (ADS)

Modifications to a high performance synthetic aperture mode for the AN/APS-506 radar are described. The modifications include improvements in the system coherency, the addition of demodulation and digitization circuitry, the installment of a strapdown inertial sensing system on the antenna, and the development of the real time motion compensation and airborne SAR processing subsystems. In the modified version of the radar pulse compression waveform generation is based on a digital waveform scheme that makes it possible to enhance the spectral purity of the radar signals and to obtain a great deal of flexibility in generating waveforms of various bandwidths.

Haslam, G. E.; vant, M. R.; Difilippo, D.

265

Determination of the Sources of Radar Scattering  

NASA Technical Reports Server (NTRS)

Fine-resolution radar backscattering measurements were proposed to determine the backscattering sources in various vegetation canopies and surface targets. The results were then used to improve the existing theoretical models of terrain scattering, and also to enhance understanding of the radar signal observed by an imaging radar over a vegetated area. Various experiments were performed on targets such as corn, milo, soybeans, grass, asphalt pavements, soil and concrete walkways. Due to the lack of available references on measurements of this type, the obtained results will be used primarily as a foundation or future experiments. The constituent backscattering characteristics of the vegetation canopies was also examined.

Moore, R. K.; Zoughi, R.

1984-01-01

266

Combustion powered thermophotovoltaic emitter system  

SciTech Connect

The US Naval Academy (USNA) has recently completed an engineering design project for a high temperature thermophotovoltaic (TPV) photon emitter. The final apparatus was to be portable, completely self contained, and was to incorporate cycle efficiency optimization such as exhaust stream recuperation. Through computer modeling and prototype experimentation, a methane fueled emitter system was designed from structural ceramic materials to fulfill the high temperature requirements necessary for high system efficiency. This paper outlines the engineering design process, discusses obstacles and solutions encountered, and presents the final design.

McHenry, R.S. [Naval Academy, Annapolis, MD (United States). Naval Architecture, Ocean and Marine Engineering

1995-07-01

267

Wideband radar phenomenology of forest stands  

Microsoft Academic Search

In this paper, experimental ultra wideband radar backscatter response of a forest stand for remote sensing using applications are presented. The radar signal is a a zero-mean pulse with a duration of 1.5 ns, and rise time of 0.1 ns occupying a bandwidth 3 GHz from 0.5 GHz-3.5 GHz. The transmitter pulse amplitude exceeds 240 V in a 50 ohm

E. D. Telpukhovskiy; V. P. Yakubov; V. L. Mironov; K. Sarabandi; G. M. Tsepelev

2003-01-01

268

SMAP RADAR Processing and Calibration  

NASA Astrophysics Data System (ADS)

The Soil Moisture Active Passive (SMAP) mission uses L-band radar and radiometer measurements to estimate soil moisture with 4% volumetric accuracy at a resolution of 10 km, and freeze-thaw state at a resolution of 1-3 km. Model sensitivities translate the soil moisture accuracy to a radar backscatter accuracy of 1 dB at 3 km resolution and a brightness temperature accuracy of 1.3 K at 40 km resolution. This presentation will describe the level 1 radar processing and calibration challenges and the choices made so far for the algorithms and software implementation. To obtain the desired high spatial resolution the level 1 radar ground processor employs synthetic aperture radar (SAR) imaging techniques. Part of the challenge of the SMAP data processing comes from doing SAR imaging on a conically scanned system with rapidly varying squint angles. The radar echo energy will be divided into range/Doppler bins using time domain processing algorithms that can easily follow the varying squint angle. For SMAP, projected range resolution is about 250 meters, while azimuth resolution varies from 400 meters to 1.2 km. Radiometric calibration of the SMAP radar means measuring, characterizing, and where necessary correcting the gain and noise contributions from every part of the system from the antenna radiation pattern all the way to the ground processing algorithms. The SMAP antenna pattern will be computed using an accurate antenna model, and then validated post-launch using homogeneous external targets such as the Amazon rain forest to look for uncorrected gain variation. Noise subtraction is applied after image processing using measurements from a noise only channel. Variations of the internal electronics are tracked by a loopback measurement which will capture most of the time and temperature variations of the transmit power and receiver gain. Long-term variations of system performance due to component aging will be tracked and corrected using stable external reference targets. Candidate targets include the Amazon rain forest and a model-corrected global ocean measurement. Radio frequency interference (RFI) signals are expected in the L-band frequency window used by the SMAP radar because many other users also operate in this band. Based on results of prior studies at JPL, SMAP L1 radar processing will use a "Slow-time thresholding" or STT algorithm to handle RFI contamination. The STT technique looks at the slow-time series associated with a given range sample, sets an appropriate threshold, and identifies any samples that rise above this threshold as RFI events. The RFI events are removed and the data are azimuth compressed without those samples. Faraday rotation affects L-band signals by rotating the polarization vector during propagation through the ionosphere. This mixes HH, VV, HV, and VH results with each other introducing another source of error. The SMAP radar is not fully polarimetric so the radar data do not provide a correction by themselves. Instead a correction must be derived from other sources. L1 radar processing will use estimates of Faraday rotation derived from externally supplied GPS-based measurements of the ionosphere total electron content (TEC). This work is supported by the SMAP project at the Jet Propulsion Laboratory, California Institute of Technology.

West, R. D.; Jaruwatanadilok, S.; Kwoun, O.; Chaubell, M. J.

2013-12-01

269

Monitoring by holographic radar systems  

NASA Astrophysics Data System (ADS)

Nowadays, radar technology represents a significant opportunity to collect useful information for the monitoring and conservation of critical infrastructures. Radar systems exploit the non-invasive interaction between the matter and the electromagnetic waves at microwave frequencies. Such an interaction allows obtaining images of the region under test from which one can infer the presence of potential anomalies such as deformations, cracks, water infiltrations, etc. This information turns out to be of primary importance in practical scenarios where the probed structure is in a poor state of preservation and renovation works must be planned. In this framework, the aim of this contribution is to describe the potentialities of the holographic radar Rascan 4/4000, a holographic radar developed by Remote Sensing Laboratory of Bauman Moscow State Technical University, as a non-destructive diagnostic tool capable to provide, in real-time, high resolution subsurface images of the sounded structure [1]. This radar provides holograms of hidden anomalies from the amplitude of the interference signal arising between the backscattered signal and a reference signal. The performance of the holographic radar is appraised by means of several experiments. Preliminary tests concerning the imaging below the floor and inside wood structures are carried out in controlled conditions at the Electromagnetic Diagnostic Laboratory of IREA-CNR. After, with reference to bridge monitoring for security aim, the results of a measurement campaign performed on the Musmeci bridge are presented [2]. Acknowledgments This research has been performed in the framework of the "Active and Passive Microwaves for Security and Subsurface imaging (AMISS)" EU 7th Framework Marie Curie Actions IRSES project (PIRSES-GA-2010-269157). REFERENCES [1] S. Ivashov, V. Razevig, I. Vasilyev, A. Zhuravlev, T. Bechtel, L. Capineri, The holographic principle in subsurface radar technology, International Symposium to Commemorate the 60th Anniversary of the Invention of Holography, Springfield, Massachusetts USA, October 27-29, pp. 183-197, 2008. [2] I. Catapano, L. Crocco, A. F. Morabito, F. Soldovieri, "Tomographic imaging of holographic GPR data for non-invasive structural assessment: the Musmeci bridge investigation", Nondestructive testing and evaluation, vol. 27, pp. 229-237, 2012.

Catapano, Ilaria; Crocco, Lorenzo; Affinito, Antonio; Gennarelli, Gianluca; Soldovieri, Francesco

2013-04-01

270

On the impulse response of monopulse radars  

NASA Astrophysics Data System (ADS)

The purpose of this study was to develop an analytical model to determine the response of an amplitude-amplitude monopulse radar to an impulsive input signal. This study was sponsored by the Air Force Electronic Warfare Center at Kelly AFB and represents a first step for determining if impulsive jamming has any merit against monopulse radar systems. From a literature review, it was determined that the receiver components most affected by an impulsive signal were filters in the receiver channel. Inverse Laplace transform techniques were used to determine the impulse response of a three-pole and a five-pole filter. A model of a logarithmic amplifier was also used. A FORTRAN computer program was written to simulate imbalances between the receiving channels of the radar. The results of the analyses showed that an impulsive signal would not cause a substantial tracking error until four to six seconds after the pulse arrive at the input of the filter, which is well out of the range gate. This signal may produce angle errors in the angle circuits of the radar without being detected by the range circuitry or the operator. It is recommended that experimental results using an impulsive electronic countermeasures signal against a monopulse radar be obtained.

Tackett, Dennis L.

1988-12-01

271

Development of optical field emitter arrays  

E-print Network

Optical field emitters are electron emission sources actuated by incident light. Optically actuated field emitters may produce ultrafast pulses of electrons when excited by ultrafast optical pulses, thus making them of ...

Yang, Yujia, S.M. Massachusetts Institute of Technology

2013-01-01

272

Optimized aperiodic highly directional narrowband infrared emitters  

E-print Network

of the molecular resonances of carbon monoxide (CO); hence, the design is suitable for the emitting portion as solar photovoltaics [5,6], these emitters may have many uses due to their emittance spectra altering

Veronis, Georgios

273

Preliminary Results of RMS Emittance Measurements Performed on the Subpicosecond Accelerator Using Beam Position Monitors  

NASA Astrophysics Data System (ADS)

The Subpicosecond Accelerator (SPA) at Los Alamos National Laboratory is a 1300MHz, 8MeV photoinjector. Concerned mainly with the exploration of bunched electron beams, the SPA facility is also used for a variety of other research. One ongoing task is the exploitation of the second moment properties of beam position monitor (BPM) signals to measure the rms emittance.(R.H. Miller, et al., ``Nonintercepting Emittance Monitor,'' Proc. 12th Int. Conf. on High Energy Accelerators, (Fermilab, 1983), p. 602 (1983).) The unique properties of photoinjector beams make Gaussian assumptions about their distribution inaccurate and traditional methods of measuring the rms emittance fail.(Bruce E. Carlsten, et. al., ``Measuring Emittance of Non-thermalized Electron Beams from Photoinjectors,'' 14th International Free Electron Conference, Kobe, Japan, August 23-28, 1992, Los Alamos National Laboratory document LAUR 92 2561.) Utilizing BPMs, however, requires no beam distribution assumptions. Presented here are our first emittance measurements with this method on SPA.

Russell, Steven J.

1997-05-01

274

Ultra Low Emittance Light Sources  

SciTech Connect

This paper outlines the special issues for reaching sub-nm emittance in a storage ring. Effects of damping wigglers, intra-beam scattering and lifetime issues, dynamic aperture optimization, control of optics, and their interrelations are covered in some detail. The unique choices for the NSLS-II are given as one example.

Bengtsson,J.

2008-06-23

275

Radar electronic warfare  

NASA Astrophysics Data System (ADS)

An overview of radar and electronic warfare is given. Definitions, common terms, and principles of radar and electronic warfare, and simple analyses of interactions between radar systems and electronic countermeasures (ECM) are presented. Electronic counter-countermeasure and electronic support measures are discussed. Background material in mathematics, electromagnetics, and probability necessary for an understanding of radar and electronic warfare is given and radar tracking models are examined. The effects of various ECM emissions on radar systems are analyzed, including discussion of active ECM and angle scanning systems, angle measurement in monopulse, and automatic gain control.

Golden, August, Jr.

276

Motion Analysis Of Radar Targets  

Microsoft Academic Search

In our problem of identifying iceberg fragments in marine radar, we have previously applied Gabor’s expansion of a signal onto a set of Gaussian windowed sinusoids (Gabor functions). A somewhat sinusoidal signature in time-frequency space characterized the near circular movement of any floating object under the influence of ocean waves. Methods based on an adaptive version of this time-frequency processing

Steve Mann; Simon Haykin

1991-01-01

277

Space based radar technology challenges  

Microsoft Academic Search

Space based radars are gaining significant acceptance for world-wide, all-weather, on-demand surveillance and earth resources monitoring. The main impediment has been affordability, followed closely by the limitations by satellite communications for providing near real time target detection data to the users. Recent advances in active electronic scanned arrays and on-board signal processing are enabling SBR development for both surface and

Mark E. Davis

2005-01-01

278

Radar image of Rio Sao Francisco, Brazil  

NASA Technical Reports Server (NTRS)

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

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

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

2000-01-01

279

Transponder-Aided Joint Calibration and Synchronization Compensation for Distributed Radar Systems  

PubMed Central

High-precision radiometric calibration and synchronization compensation must be provided for distributed radar system due to separate transmitters and receivers. This paper proposes a transponder-aided joint radiometric calibration, motion compensation and synchronization for distributed radar remote sensing. As the transponder signal can be separated from the normal radar returns, it is used to calibrate the distributed radar for radiometry. Meanwhile, the distributed radar motion compensation and synchronization compensation algorithms are presented by utilizing the transponder signals. This method requires no hardware modifications to both the normal radar transmitter and receiver and no change to the operating pulse repetition frequency (PRF). The distributed radar radiometric calibration and synchronization compensation require only one transponder, but the motion compensation requires six transponders because there are six independent variables in the distributed radar geometry. Furthermore, a maximum likelihood method is used to estimate the transponder signal parameters. The proposed methods are verified by simulation results. PMID:25794158

Wang, Wen-Qin

2015-01-01

280

Transponder-aided joint calibration and synchronization compensation for distributed radar systems.  

PubMed

High-precision radiometric calibration and synchronization compensation must be provided for distributed radar system due to separate transmitters and receivers. This paper proposes a transponder-aided joint radiometric calibration, motion compensation and synchronization for distributed radar remote sensing. As the transponder signal can be separated from the normal radar returns, it is used to calibrate the distributed radar for radiometry. Meanwhile, the distributed radar motion compensation and synchronization compensation algorithms are presented by utilizing the transponder signals. This method requires no hardware modifications to both the normal radar transmitter and receiver and no change to the operating pulse repetition frequency (PRF). The distributed radar radiometric calibration and synchronization compensation require only one transponder, but the motion compensation requires six transponders because there are six independent variables in the distributed radar geometry. Furthermore, a maximum likelihood method is used to estimate the transponder signal parameters. The proposed methods are verified by simulation results. PMID:25794158

Wang, Wen-Qin

2015-01-01

281

On phased-array radar tracking and parameter control  

Microsoft Academic Search

Based on a simple model of a ground-based phased-array radar used for a multiple-target surveillance task, beam scheduling, positioning, and radar parameters like signal-to-noise ratio, track sharpness, and detection threshold have been optimized with respect to the radar\\/computer load induced by tracking. From this the minimum energy necessary for track maintenance during surveillance can be derived

G. van Keuk; Samuel S. Blackman

1993-01-01

282

Noise and clutter rejection in radars and imaging sensors; Proceedings of the International Symposium, Tokyo, Japan, October 22-24, 1984  

NASA Astrophysics Data System (ADS)

Advanced techniques and systems for image processing and information extraction are considered along with subsurface radars, the polarization and statistical properties of clutter, characteristics of clutter properties, medical and acoustic imaging, remote sensing, radar signal processing, image processing, tracking techniques, antennas, and the imaging radar. Radar systems are discussed, taking into account radar image processing for surface aircraft recognition, clutter suppression in air traffic control radars, the Time Reference Scanning Beam (TRSB) Microwave Landing System (MLS) modelling and analysis in multipath environment, echo enhancement for a marine radar by new display techniques, compact FSK signals for radar clutter rejection, an energy efficient synthesis of an ambiguity surface, and experimental results on discrimination of radar signals by polarization. Attention is given to fast-scan processing in maritime surveillance radar, a distributed digital processing architecture for adaptive suppression of radar clutter and interference, and the noise properties of generators.

Musha, T.; Suzuki, T.; Ogura, H.

283

Hail detection using S-band dual polarization radar  

NASA Astrophysics Data System (ADS)

The Korea Meteorological Administration(KMA) plans to replace current radars with the S-band dual polarization radars until 2016. So we need to develop an application technology of the S-band dual polarization radar of KMA. The dual polarization radar is capable of measuring the reflectivity ZH, differential reflectivity ZDR, specific differential phase KDP and cross-correlation coefficient ?HV. Using multi-parameter radar information helps to significantly improve the quality of the radar data, distinguish rain echos from the radar signals caused by other scatters (snow, ground clutter, chaff etc.). Additionally, Hydrometeor classification (rain, snow, hail, etc.) is one of the primary benefits of dual-polarization radar. However, current research on the S-band dual polarization hydrometeor classification is not in significant progress in Korea. So the purposes of this research are to perform application tests of hydrometeor classification algorithm and make operational system of S-band dual polarization radar of KMA. For this research, we used BSL S-band dual polarization radar data and NIMR-X hydrometeor classification algorithm of the National Institute of Meteorological Research(NIMR). This radar has been operated by the Ministry of Land, Transport, and Maritime affairs(MLTM) and NIMR-X hydrometeor classification algorithm was developed through joint research with the National Center for Atmospheric Research(NCAR).

Heo, S.; Kang, M.; Nam, K.; Jung, H.

2013-12-01

284

Remorque RADAR Description technique  

E-print Network

ANNEXE: Remorque RADAR Description technique Le but de la remorque est de transporter un RADAR et pour héberger l'électronique radar et son opérateur. Caractéristiques générales de la remorque : · PTC'un côté, une baie de l'autre. Un hublot sur le toit et une baie donnant sur la partie RADAR. Un plafonnier

Heurteaux, Yanick

285

Lunar radar backscatter studies  

NASA Technical Reports Server (NTRS)

The lunar surface material in the Plato area is characterized using Earth based visual, infrared, and radar signatures. Radar scattering in the lunar regolith with an existing optical scattering computer program is modeled. Mapping with 1 to 2 km resolution of the Moon using a 70 cm Arecibo radar is presented.

Thompson, T. W.

1979-01-01

286

Investigations on the sensitivity of a stepped-frequency radar utilizing a vector network analyzer for Ground Penetrating Radar  

NASA Astrophysics Data System (ADS)

Employing a continuous-wave radar system, with the stepped-frequency radar being one type of this class, all reflections from the environment are present continuously and simultaneously at the receiver. Utilizing such a radar system for Ground Penetrating Radar purposes, antenna cross-talk and ground bounce reflection form an overall dominant signal contribution while reflections from objects buried in the ground are of quite weak amplitude due to attenuation in the ground. This requires a large dynamic range of the receiver which in turn requires high sensitivity of the radar system. In this paper we analyze the sensitivity of our vector network analyzer utilized as stepped-frequency radar system for GPR pipe detection. We furthermore investigate the performance of increasing the sensitivity of the radar by means of appropriate averaging and low-noise pre-amplification of the received signal. It turns out that the improvement in sensitivity actually achievable may differ significantly from theoretical expectations. In addition, we give a descriptive explanation why our appropriate experiments demonstrate that the sensitivity of the receiver is independent of the distance between the target object and the source of dominant signal contribution. Finally, our investigations presented in this paper lead to a preferred setting of operation for our vector network analyzer in order to achieve best detection capability for weak reflection amplitudes, hence making the radar system applicable for Ground Penetrating Radar purposes.

Seyfried, Daniel; Schubert, Karsten; Schoebel, Joerg

2014-12-01

287

Nonlocality from N>2 independent single-photon emitters  

SciTech Connect

We demonstrate that intensity correlations of second order in the fluorescence light of N>2 single-photon emitters may violate locality while the visibility of the signal remains below 1/{radical}(2){approx_equal}71%. For this, we derive a homogeneous Bell-Wigner-type inequality, which can be applied to a broad class of experimental setups. We trace the violation of this inequality back to path entanglement created by the process of detection.

Thiel, C.; Wiegner, R.; Zanthier, J. von [Institut fuer Optik, Information und Photonik, Universitaet Erlangen-Nuernberg, D-91058 Erlangen (Germany); Agarwal, G. S. [Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078-3072 (United States)

2010-09-15

288

A land based radar polarimeter processing system  

E-print Network

for the RDADS iSBC-80/24 Processor. 10 Processor Port Assignments for IFC Interface . 11 IFC Channel Assignments 12 IFC Control Channel (2) Signals. 24 25 26 27 30 30 32 34 35 40 43 43 FIGURE LIST OF FIGURES Page 1 Elevation Angle for Radar... the use of transfer switches that have a single level sensitive control input. The radar head numbers specified in Table 2 were used during 25 TABLE 2 Cal/Op Control Port Signal Assignments Port EB Bit Assignment Head I Cal/Op Control 0 Head I Cal...

Kronke, Chester William

1984-01-01

289

Performance analysis of various UWB radar approaches for medical diagnostics  

Microsoft Academic Search

In this paper, the challenge of the UWB radar for medical applications is presented in terms of high signal attenuation and multiple reflections in human tissues. Different UWB radar approaches are reviewed in this research. The IR- UWB approaches, the PN approach and the frequency measurement with the Vector Network Analyzer are introduced and discussed. Furthermore, the demonstrators of all

Xuyang Li; Steffen Scherr; Leen Sit; Elena Pancera; Thomas Zwick

2011-01-01

290

MIMO radar systems Permanent members: F. Nadal, P. Jardin.  

E-print Network

. These systems can increase the radar resolution, the number of targets that can be identified the possibility of sending the transmitted power towards the directions of multiple targets (Figure 1). To date, most of the work on MIMO radar has been performed assuming the signals are narrowband. We started our

Baudoin, Geneviève

291

A digital leakage cancellation scheme for monostatic FMCW radar  

Microsoft Academic Search

A novel heterodyne scheme based on real-time digital signal processing is proposed for leakage cancellation in monostatic frequency modulated continuous wave (FMCW) radars. Compared to conventional analog implementation, the advantages of the proposed scheme include that the DC offset existing in analog mixers affecting the cancellation performance are eliminated. A radar test bed at 26 GHz has been built. The

Kaihui Lin; Razmig Hagop Messerian; Yuanxun Wang

2004-01-01

292

Space-time adaptive processing for airborne radar  

Microsoft Academic Search

Future airborne radars will be required to detect targets in an interference background comprised of clutter and jamming. Space-time adaptive processing (STAP) refers to multidimensional adaptive filtering algorithms that simultaneously combine the signals from the elements of an array antenna and the multiple pulses of a coherent radar waveform, to suppress interference and provide target detection. STAP can improve detection

James Ward

1994-01-01

293

Independent evaluation of the ability of spaceborne radar and lidar  

E-print Network

Chapter 1 Independent evaluation of the ability of spaceborne radar and lidar to retrieve the microphysical and radiative properties of ice clouds Summary. The combination of radar and lidar in space offers, that of correcting the lidar signal for extinction. In this chapter "blind tests" of these two algorithms are carried

Hogan, Robin

294

K-Distribution and Polarimetric Terrain Radar Clutter  

Microsoft Academic Search

A multivariate K- distribution is proposed to model the statistics of fully polarimetric radar data from earth terrain with polarizations HH, HV, VH, and VV. In this approach, correlated polarizations of radar signals, as characterized by a covariance matrix, are treated as the sum of N n- dimensional random vectors; N obeys the negative binomial distribution with a parameter ?

S. H. Yueh; J. A. Kong; J. K. Jao; R. T. Shin; L. M. Novak

1989-01-01

295

Computer generation of correlated non-Gaussian radar clutter  

Microsoft Academic Search

We develop computer simulation procedures which enable us to generate any correlated non-Gaussian radar clutter that can be modeled as a spherically invariant random process (SIRP). In most cases, when the clutter is a correlated non-Gaussian random process, performance of the optimal radar signal processor cannot be evaluated analytically. Therefore, in order to evaluate such processors, there is a need

Muralidhar Rangaswamy; Donald Weiner; Aydin Ozturk

1995-01-01

296

Beam emittance measurements at Fermilab  

SciTech Connect

We give short overview of various beam emittance measurement methods, currently applied at different machine locations for the Run II collider physics program at Fermilab. All these methods are based on beam profile measurements, and we give some examples of the related instrumentation techniques. At the end we introduce a multi-megawatt proton source project, currently under investigation at Fermilab, with respect to the beam instrumentation challenges.

Wendt, Manfred; Eddy, Nathan; Hu, Martin; Scarpine, Victor; Syphers, Mike; Tassotto, Gianni; Thurman-Keup, Randy; Yang, Ming-Jen; Zagel, James; /Fermilab

2008-01-01

297

Metamaterial selective emitters for photodiodes  

NASA Astrophysics Data System (ADS)

This work demonstrates metamaterial (MM) selective thermal emitters for potential use with energy harvesting photodiodes, such as thermophotovoltaic cells. Preliminary structures have been designed, simulated, and fabricated using CST Microwave Studio and microfabrication techniques including electron beam evaporation, atomic layer deposition, and electron beam lithography, respectively. Samples were tested to determine the effect of top layer metal thickness on the absorption of these devices. Preliminary simulation and testing was also performed to design a device for operation at 500°C.

DeMeo, Dante F.; Pfeister, Nicole A.; Shemelya, Corey M.; Vandervelde, Thomas

2014-03-01

298

Alpha particle emitters in medicine  

SciTech Connect

Radiation-induced cancer of bone, liver and lung has been a prominent harmful side-effect of medical applications of alpha emitters. In recent years, however, the potential use of antibodies labeled with alpha emitting radionuclides against cancer has seemed promising because alpha particles are highly effective in cell killing. High dose rates at high LET, effectiveness under hypoxic conditions, and minimal expectancy of repair are additional advantages of alpha emitters over antibodies labeled with beta emitting radionuclides for cancer therapy. Cyclotron-produced astatine-211 ({sup 211}At) and natural bismuth-212 ({sup 212}Bi) have been proposed and are under extensive study in the United States and Europe. Radium-223 ({sup 223}Ra) also has favorable properties as a potential alpha emitting label, including a short-lived daughter chain with four alpha emissions. The radiation dosimetry of internal alpha emitters is complex due to nonuniformly distributed sources, short particle tracks, and high relative specific ionization. The variations in dose at the cellular level may be extreme. Alpha-particle radiation dosimetry, therefore, must involve analysis of statistical energy deposition probabilities for cellular level targets. It must also account fully for nonuniform distributions of sources in tissues, source-target geometries, and particle-track physics. 18 refs., 4 figs.

Fisher, D.R.

1989-09-01

299

Stepped frequency ground penetrating radar  

DOEpatents

A stepped frequency ground penetrating radar system is described comprising an RF signal generating section capable of producing stepped frequency signals in spaced and equal increments of time and frequency over a preselected bandwidth which serves as a common RF signal source for both a transmit portion and a receive portion of the system. In the transmit portion of the system the signal is processed into in-phase and quadrature signals which are then amplified and then transmitted toward a target. The reflected signals from the target are then received by a receive antenna and mixed with a reference signal from the common RF signal source in a mixer whose output is then fed through a low pass filter. The DC output, after amplification and demodulation, is digitized and converted into a frequency domain signal by a Fast Fourier Transform. A plot of the frequency domain signals from all of the stepped frequencies broadcast toward and received from the target yields information concerning the range (distance) and cross section (size) of the target.

Vadnais, Kenneth G. (Ojai, CA); Bashforth, Michael B. (Buellton, CA); Lewallen, Tricia S. (Ventura, CA); Nammath, Sharyn R. (Santa Barbara, CA)

1994-01-01

300

Automatic identification of bird targets with radar via patterns produced by  

E-print Network

Automatic identification of bird targets with radar via patterns produced by wing flapping Serge, `Vogelwarte Helgoland', 26386 Wilhelmshaven, Germany Bird identification with radar is important for bird meteorology. In a study on bird migration, radar signals from birds, insects and ground clutter were recorded

Loon, E. Emiel van

301

SCANNING CLOUD RADAR OBSERVATIONS AT AZORES: PRELIMINARY 3D CLOUD PRODUCTS  

E-print Network

SCANNING CLOUD RADAR OBSERVATIONS AT AZORES: PRELIMINARY 3D CLOUD PRODUCTS P. Kollias, I. Jo, A, NY www.bnl.gov ABSTRACT The deployment of the Scanning W-Band ARM Cloud Radar (SWACR) during the AMF campaign at Azores signals the first deployment of an ARM Facility-owned scanning cloud radar and offers

302

Bistatic radar imaging of the marine environment. Part II: simulation and results analysis  

E-print Network

1 Bistatic radar imaging of the marine environment. Part II: simulation and results analysis present a bistatic, polarimetric and real aper- ture Marine Radar Simulator (MaRS) producing pseudo-raw radar signal. The simulation takes the main elements of the environment into account (sea temperature

Boyer, Edmond

303

Departement TSI Restitution du relief `a partir d'images radar  

E-print Network

D´epartement TSI Restitution du relief `a partir d'images radar par radarclinom´etrie Sophie . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.1.1 Inter^et des capteurs radar par rapport aux capteurs optiques 19 2.1.2 Signal delivre par l . . . . . . . . . . . . . . . . . . . . . . 26 2.3 Images radar utilisees . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.3.1 Les

Paris-Sud XI, Université de

304

Current radar-responsive tag development activities at Sandia National Laboratories  

Microsoft Academic Search

Over the past ten years, Sandia has developed RF radar responsive tag systems and supporting technologies for various government agencies and industry partners. RF tags can function as RF transmitters or radar transponders that enable tagging, tracking, and location determination functions. Expertise in tag architecture, microwave and radar design, signal analysis and processing techniques, digital design, modeling and simulation, and

Richard C. Ormesher; Kenneth W. Plummer; Lars M. Wells

2004-01-01

305

Radar Meteorology Tutorial  

NSDL National Science Digital Library

Brian McNoldy at Multi-community Environmental Storm Observatory (MESO) educates the public about the use of radar in meteorology in this pdf document. After reading about the history of radar, visitors can find out how radar can detect storms by transmitting a high-power beam of radiation. Students can learn how scatter, absorption, frequencies, scan angles, and moments impact the radar display. With the help of many example images, the author also discusses how to interpret the images collected. At the end of the online document, visitors can learn about the characteristics and capabilities of NEXRAD WSR-88D, the radar used throughout the United States.

McNoldy, Brian

306

Transverse Emittance Reduction with Tapered Foil  

SciTech Connect

The idea of reducing transverse emittance with tapered energy-loss foil is proposed by J.M. Peterson in 1980s and recently by B. Carlsten. In this paper, we present the physical model of tapered energy-loss foil and analyze the emittance reduction using the concept of eigen emittance. The study shows that, to reduce transverse emittance, one should collimate at least 4% of particles which has either much low energy or large transverse divergence. The multiple coulomb scattering is not trivial, leading to a limited emittance reduction ratio. Small transverse emittances are of essential importance for the accelerator facilities generating free electron lasers, especially in hard X-ray region. The idea of reducing transverse emittance with tapered energy-loss foil is recently proposed by B. Carlsten [1], and can be traced back to J.M. Peterson's work in 1980s [2]. Peterson illustrated that a transverse energy gradient can be produced with a tapered energy-loss foil which in turn leads to transverse emittance reduction, and also analyzed the emittance growth from the associated multiple coulomb scattering. However, what Peterson proposed was rather a conceptual than a practical design. In this paper, we build a more complete physical model of the tapered foil based on Ref. [2], including the analysis of the transverse emittance reduction using the concept of eigen emittance and confirming the results by various numerical simulations. The eigen emittance equals to the projected emittance when there is no cross correlation in beam's second order moments matrix [3]. To calculate the eigen emittances, it requires only to know the beam distribution at the foil exit. Thus, the analysis of emittance reduction and the optics design of the subsequent beam line section can be separated. In addition, we can combine the effects of multiple coulomb scattering and transverse energy gradient together in the beam matrix and analyze their net effect. We find that,when applied to an electron linac or electron beam line, the energy spread increase and angular growth due to multiple scattering are not trivial; as a result, the transverse emittance can only be reduced with a limited ratio, e.g. down to about 65% the original value. The contents of this paper are arranged as follows. In Sec. II, we build the physical model of the tapered foil, derive the transverse eigen emittance and discuss the emittance reduction criteria. In Sec. III, we implement numerical simulations to verify the physical model; and in Sec. IV, we present numerical experiments and subsequent beam line to remove the transverse energy gradient to demonstrate the applicability of such method. Conclusions are given in the last section.

Jiao, Yi; Chao, Alex; Cai, Yunhai; /SLAC

2011-12-09

307

Two terminal micropower radar sensor  

DOEpatents

A simple, low power ultra-wideband radar motion sensor/switch configuration connects a power source and load to ground. The switch is connected to and controlled by the signal output of a radar motion sensor. The power input of the motion sensor is connected to the load through a diode which conducts power to the motion sensor when the switch is open. A storage capacitor or rechargeable battery is connected to the power input of the motion sensor. The storage capacitor or battery is charged when the switch is open and powers the motion sensor when the switch is closed. The motion sensor and switch are connected between the same two terminals between the source/load and ground. 3 figs.

McEwan, T.E.

1995-11-07

308

Two terminal micropower radar sensor  

DOEpatents

A simple, low power ultra-wideband radar motion sensor/switch configuration connects a power source and load to ground. The switch is connected to and controlled by the signal output of a radar motion sensor. The power input of the motion sensor is connected to the load through a diode which conducts power to the motion sensor when the switch is open. A storage capacitor or rechargeable battery is connected to the power input of the motion sensor. The storage capacitor or battery is charged when the switch is open and powers the motion sensor when the switch is closed. The motion sensor and switch are connected between the same two terminals between the source/load and ground.

McEwan, Thomas E. (Livermore, CA)

1995-01-01

309

A lightweight ground penetrating radar  

SciTech Connect

The detection of buried objects, particularly unexploded ordnance (UXO), has gained significant interest in the US in the late 1990s. The desire to remediate the thousands of sites worldwide has become an increasing humanitarian concern. The application of radar to this problem has received renewed attention. Bechtel Nevada, Special Technologies Laboratory (STL) has developed several frequency modulated, continuous wave (FM-CW) ground penetrating radar (GPR) units for the US Department of Energy since 1984. To meet these new technical requirements for high resolution data and UXO detection, STL is moving forward with advances to GPR technology, signal processing, and imaging with the development of an innovative system. The goal is to design and fabricate a lightweight, battery operated unit that does not require surface contact and can be operated by a novice user.

Koppenjan, S.K.; Allen, C.M.; Gardner, D.; Wong, H.R.

1998-12-31

310

Wideband radar micro-doppler applications  

NASA Astrophysics Data System (ADS)

Wideband radar provides a significant improvement over traditional narrowband radars for micro-Doppler analysis because the high bandwidth can be used to separate many of the signals in range, allowing a simpler decomposition of the micro-Doppler signals. Recent wideband radar work has focused on micro-Doppler, but there is a point where the narrowband approach used to analyze the micro-Doppler signals breaks down. The effect is shown to be independent of frequency, but the error relative to the bandwidth is shown to be inversely proportional to the frequency and proportional to the velocity of the subject. This error can create a smearing effect in the observed Doppler if it is not corrected, leading to reduced signal-to-noise and the appearance of more diffuse targets in Doppler space. In range-space, wideband data can also break the subject into several range bins, affecting the observed signal to noise ratio. The possible applications of wideband micro-Doppler radar are also shown, including the separation of arm movement from human motion which implies that the arms are not encumbered.

Tahmoush, Dave

2013-05-01

311

2. VIEW SOUTHWEST, prime search radar tower, height finder radar ...  

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

2. VIEW SOUTHWEST, prime search radar tower, height finder radar towards, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

312

Modern Radar Techniques for Geophysical Applications: Two Examples  

NASA Technical Reports Server (NTRS)

The last decade of the evolution of radar was heavily influenced by the rapid increase in the information processing capabilities. Advances in solid state radio HF devices, digital technology, computing architectures and software offered the designers to develop very efficient radars. In designing modern radars the emphasis goes towards the simplification of the system hardware, reduction of overall power, which is compensated by coding and real time signal processing techniques. Radars are commonly employed in geophysical radio soundings like probing the ionosphere; stratosphere-mesosphere measurement, weather forecast, GPR and radio-glaciology etc. In the laboratorio di Geofisica Ambientale of the Istituto Nazionale di Geofisica e Vulcanologia (INGV), Rome, Italy, we developed two pulse compression radars. The first is a HF radar called AIS-INGV; Advanced Ionospheric Sounder designed both for the purpose of research and for routine service of the HF radio wave propagation forecast. The second is a VHF radar called GLACIORADAR, which will be substituting the high power envelope radar used by the Italian Glaciological group. This will be employed in studying the sub glacial structures of Antarctica, giving information about layering, the bed rock and sub glacial lakes if present. These are low power radars, which heavily rely on advanced hardware and powerful real time signal processing. Additional information is included in the original extended abstract.

Arokiasamy, B. J.; Bianchi, C.; Sciacca, U.; Tutone, G.; Zirizzotti, A.; Zuccheretti, E.

2005-01-01

313

Radar systems for a polar mission, volume 1  

NASA Technical Reports Server (NTRS)

The application of synthetic aperture radar (SAR) in monitoring and managing earth resources is examined. Synthetic aperture radars form a class of side-looking airborne radar, often referred to as coherent SLAR, which permits fine-resolution radar imagery to be generated at long operating ranges by the use of signal processing techniques. By orienting the antenna beam orthogonal to the motion of the spacecraft carrying the radar, a one-dimensional imagery ray system is converted into a two-dimensional or terrain imaging system. The radar's ability to distinguish - or resolve - closely spaced transverse objects is determined by the length of the pulse. The transmitter components receivers, and the mixer are described in details.

Moore, R. K.; Claassen, J. P.; Erickson, R. L.; Fong, R. K. T.; Komen, M. J.; Mccauley, J.; Mcmillan, S. B.; Parashar, S. K.

1977-01-01

314

Natural oil seep detection in the Santa Barbara Channel, California, with Shuttle Imaging Radar  

NASA Astrophysics Data System (ADS)

Natural submarine oil seeps in the Santa Barbara Channel, California, were detected by the first Shuttle Imaging Radar (SIR-A). Oil slicks on the ocean are seen in radar imagery as areas of decreased radar signal return that result from a damping of surface roughness. Orbital radar imagery shows promise as an effective and efficient means of mapping submarine oil seeps as sources of naturally occurring oil slicks.

Estes, John E.; Crippen, Robert E.; Star, Jeffrey L.

1985-04-01

315

Ka-band ocean wave\\/radar modulation transfer function: a comparative study  

Microsoft Academic Search

For radar systems looking at moderate angles of incidence most scattering theories assume that the prime scatterers are ripples. Various mechanisms relate the modulation of radar returned power to the long ocean waves. The most important contributors to the radar-signal modulation for real-aperture radars are the tilt and aero-hydrodynamic modulation. The tilt modulation is a purely geometric effect and can

S. Haimov; B. Gotwols; William Plant; Richard K. Moore

1994-01-01

316

Alpine radar conversion for LAWR  

NASA Astrophysics Data System (ADS)

The Local Area Weather Radar (LAWR) is a ship-born weather radar system operating in X-band developed by the DHI Group to detect precipitation in urban areas. To date more than thirty units are installed in different settings around the world. A LAWR was also deployed in the Alps, at 3883 m a.s.l. on the Kl. Matterhorn (Valais, Switzerland). This was the highest LAWR of the world and it led to the development of an Alpine LAWR system that, besides featuring important technological improvements needed to withstand the severe Alpine conditions, required the development of a new Alpine Radar COnversion Model (ARCOM), which is the main focus of this contribution. The LAWR system is equipped with the original FURUNO fan-beam slotted antenna and the original logarithmic receiver, which limits the radar observations to the video signal (L) withour providing the reflectivity (Z). The beam is 0.95 deg wide and 20 deg high. It can detect precipitation to a max range of 60 km. In order to account for the limited availability of raw signal and information and the specific mountain set-up, the conversion model had to be developed differently from the state-of-the-art radar conversion technique used for this class of radars. In particular, the ARCOM is based on a model used to simulate a spatial dependent factor, hereafter called ACF, which is in turn function of parameters that take in account climatological conditions, also used in other conversion methods, but additionally accounting for local radar beam features and for orographic forcings such as the effective sampling power (sP), which is modelled by means of antenna pattern, geometric ground clutter and their interaction. The result is a conversion factor formulated to account for a range correction that is based on the increase of the sampling volume, partial beam blocking and local climatological conditions. The importance of the latter in this study is double with respect to the standard conversion technique for this class of radars, because it accounts for the large variability of hydrometeors reflectivity and vertical hydrometeors positioning (echo-top), which is strongly influenced by the high location of the radar. The ARCOM procedure is in addition embedded in a multistep quality control framework, which also includes the calibration on raingauge observations, and can be summarized as follow: 1) correction of both LAWR and raingauge observations for known errors (e.g. magnetron decay and heated-related water loss) 2) evaluation of the local Pearson's correlation coefficient (PCC) as estimator of the linear correlation between raingauge and LAWR observations (logarithmic receiver); 3) computation of the local ACF in the form of the local linear regression coefficient between raingauge and LAWR observations; 4) calibration of the ARCOM, i.e. definition of the parametrization able to reproduce the spatial variability of ACF as function of the local sP, being the PCCs used as weight in the calibration procedure. The resulting calibrated ARCOM finally allows, in any ungauged mountain spot, to convert LAWR observations into precipitation rate. The temporal and the spatial transferability of the ARCOM are evaluated via split-sample and a take-one-out cross validation. The results revealed good spatial transferability and a seasonal bias within 7%, thus opening new opportunities for local range distributed measurements of precipitation in mountain regions.

Savina, M.; Burlando, P.

2012-04-01

317

Analog automatic control loops in radar and EW (Electronic Warfare)  

NASA Astrophysics Data System (ADS)

This report discusses the design and analysis of the basic building blocks of many radar and Electronic Warfare (EW) systems, active and semiactive missiles, and antiradiation missiles (ARMs), namely automatic gain control, signal thresholding, and range tracking.

Hughes, Richard Smith

1988-11-01

318

FREQUENCY DEPENDENT ATTENUATION ANALYSIS OF GROUND-PENETRATING RADAR DATA  

E-print Network

FREQUENCY DEPENDENT ATTENUATION ANALYSIS OF GROUND- PENETRATING RADAR DATA John H. Bradford, CGISS, Boise State University, Boise, ID Abstract I investigate the frequency dependence of attenuation materials attenuation is approximately linear with frequency over the bandwidth of the GPR signal

Barrash, Warren

319

Prospects of the WSR-88D Radar for Cloud Studies  

E-print Network

Sounding of nonprecipitating clouds with the 10-cm wavelength Weather Surveillance Radar-1988 Doppler (WSR-88D) is discussed. Readily available enhancements to signal processing and volume coverage patterns of the WSR-88D allow observations of a...

Melnikov, Valery M.; Zrni?, Dusan S.; Doviak, Richard J.; Chilson, Phillip B.; Mechem, David B.; Kogan, Yefim L.

2011-04-01

320

Radar Imaging Systems Joseph Charpentier  

E-print Network

Radar Imaging Systems Joseph Charpentier Department of Computing Sciences Villanova University types of radar imaging systems; synthetic aperture radar (SAR), through-the-wall radar, and digital holographic near field radar. Each system surveyed experiments that improved the quality of the resulting

321

Emittance Growth in the NLCTA First Chicane  

SciTech Connect

In this paper, the emittance growth in the NLCTA (Next Linear Collider Test Accelerator) first chicane region is evaluated by simulation studies. It is demonstrated that the higher order fields of the chicane dipole magnet and the dipole corrector magnet (which is attached on the quadrupoles) are the main contributions for the emittance growth, especially for the case with a large initial emittance ({gamma}{epsilon}{sub 0} = 5 {micro}m for instance). These simulation results agree with the experimental observations.

Sun, Yipeng; Adolphsen, Chris; /SLAC

2011-08-19

322

30. Perimeter acquisition radar building room #318, showing radar control. ...  

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

30. Perimeter acquisition radar building room #318, showing radar control. Console and line printers - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

323

3. VIEW NORTHWEST, height finder radar towers, and radar tower ...  

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

3. VIEW NORTHWEST, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

324

Analysis of waveforms for bistatic radar systems  

NASA Astrophysics Data System (ADS)

The transmitter and receiver of Bistatic Radar Systems are located at different positions. It is therefore possible to transmit and receive simultaneously. This opens up the possibility of using continuous wave (CW) signals. This report shows how traditional pulse compression codes can be analyzed and enhanced, when adjusted to CW, with special attention paid to elude detection.

Oreborn, U.

1994-06-01

325

Generating nonlinear FM chirp waveforms for radar.  

SciTech Connect

Nonlinear FM waveforms offer a radar matched filter output with inherently low range sidelobes. This yields a 1-2 dB advantage in Signal-to-Noise Ratio over the output of a Linear FM waveform with equivalent sidelobe filtering. This report presents design and implementation techniques for Nonlinear FM waveforms.

Doerry, Armin Walter

2006-09-01

326

Angular accuracy of a phased array radar  

Microsoft Academic Search

One type of phased-array radar of current interest employs an array of separate receiving elements, each followed by an individual amplifier. These individual signals are combined coherently to form one or more receiving beams for searching, tracking, or performing both functions simultaneously. This paper presents an approach to the theory of angle measurement with a phased array of this type.

L. Brennan

1961-01-01

327

An overview of impulse radar phenomenon  

Microsoft Academic Search

An overview is presented of some of the interesting issues concerning impulse waveforms on materials. An attempt is made to analyze such phenomena as molecular relaxation, signal precursor effects, self-induced transparency, and the natural resonance theory. Proposed applications for impulse radar are discussed

David L. Black; ASDIENA CR; Wright-Patterson AFB

1992-01-01

328

Radar observations of F region equatorial irregularities  

Microsoft Academic Search

Experimental results obtained with the Jicamarca radar and a new digital processing system during spread F conditions are presented. The data consist of two-dimensional maps showing backscatter power and samples of frequency spectra of the backscatter signals as a function of altitude and time. Almost simultaneous spread F backscatter power and incoherent scatter observations of electron density and vertical drifts

Ronald F. Woodman; César La Hoz

1976-01-01

329

Planetary radar studies  

NASA Technical Reports Server (NTRS)

A catalog of lunar and radar anomalies was generated to provide a base for comparison with Venusian radar signatures. The relationships between lunar radar anomalies and regolith processes were investigated, and a consortium was formed to compare lunar and Venusian radar images of craters. Time was scheduled at the Arecibo Observatory to use the 430 MHz radar to obtain high resolution radar maps of six areas of the lunar suface. Data from 1978 observations of Mare Serenitas and Plato are being analyzed on a PDP 11/70 computer to construct the computer program library necessary for the eventual reduction of the May 1981 and subsequent data acquisitions. Papers accepted for publication are presented.

Thompson, T. W.; Cutts, J. A.

1981-01-01

330

Laser radar in robotics  

SciTech Connect

In this paper the authors describe the basic operating principles of laser radar sensors and the typical algorithms used to process laser radar imagery for robotic applications. The authors review 12 laser radar sensors to illustrate the variety of systems that have been applied to robotic applications wherein information extracted from the laser radar data is used to automatically control a mechanism or process. Next, they describe selected robotic applications in seven areas: autonomous vehicle navigation, walking machine foot placement, automated service vehicles, manufacturing and inspection, automotive, military, and agriculture. They conclude with a discussion of the status of laser radar technology and suggest trends seen in the application of laser radar sensors to robotics. Many new applications are expected as the maturity level progresses and system costs are reduced.

Carmer, D.C.; Peterson, L.M. [Environmental Research Inst. of Michigan, Ann Arbor, MI (United States)

1996-02-01

331

MIMO radar, SIMO radar, and IFIR radar: a P. P. Vaidyanathan and Piya Pal  

E-print Network

MIMO radar, SIMO radar, and IFIR radar: a comparison P. P. Vaidyanathan and Piya Pal Dept and SIMO radar systems for the case where the transmitter and receiver are collocated. The simplicity of the application allows one to see clearly where the advantages of MIMO radar come from, and what the tradeoffs are

Vaidyanathan, P. P.

332

Caribbean Radar Cases  

NSDL National Science Digital Library

This module presents radar case studies taken from events in the Caribbean that highlight radar signatures of severe weather. These cases include examples of deep convection, squall lines, bow echoes, tornadoes, and heavy rain resulting in flooding. Each case study includes a discussion of the conceptual models of each type of event as a review before showing the radar signatures and allowing the learner to analyze each one.

2014-09-14

333

The Invisible Radar Triangle  

NSDL National Science Digital Library

Students learn about radar imaging and its various military and civilian applications that include recognition and detection of human-made targets, and the monitoring of space, deforestation and oil spills. They learn how the concepts of similarity and scaling are used in radar imaging to create three-dimensional models of various targets. Students apply the critical attributes of similar figures to create scale models of a radar imaging scenario using infrared range sensors (to emulate radar functions) and toy airplanes (to emulate targets). They use technology tools to measure angles and distances, and relate the concept of similar figures to real-world applications.

2014-09-18

334

Extracting radar micro-Doppler signatures of helicopter rotating rotor blades using K-band radars  

NASA Astrophysics Data System (ADS)

Helicopter identification has been an attractive topic. In this paper, we applied radar micro-Doppler signatures to identify helicopter. For identifying the type of a helicopter, besides its shape and size, the number of blades, the length of the blade, and the rotation rate of the rotor are important features, which can be estimated from radar micro-Doppler signatures of the helicopter's rotating rotor blades. In our study, K-band CW/FMCW radars are used for collecting returned signals from helicopters. By analyzing radar micro-Doppler signatures, we can estimate the number of blades, the length of the blade, the angular rotation rate of the rotating blade, and other necessary parameters for identifying the type of a helicopter.

Chen, Rachel; Liu, Baokun

2014-06-01

335

Generalized radar/radiometry imaging problems  

E-print Network

Paper Generalized radar/radiometry imaging problems Ivan Prudyus, Sviatoslav Voloshynovskiy, Andriy- ing simulation based on radar, synthetic aperture radar (SAR) and radiometry systems are presented systems, synthetic aperture radar, spatio-temporal imaging. 1. Introduction Resolution of radar

Genève, Université de

336

Thermophotovoltaic Generators Using Selective Metallic Emitters  

NASA Technical Reports Server (NTRS)

In the literature to date on thermophotovoltaic (TPV) generators, two types of infrared emitter's have been emphasized : gray body emitters and rare earth oxide selective emitters. The gray body emitter is defined as an emitter with a spectral emissivity independent of wavelength whereas the rare earth oxide selective emitter is idealized as a delta function emitter with a high emissivity at a select wavelength and a near zero emissivity at all other wavelengths. Silicon carbide is an example of a gray body emitter and ER-YAG is an example of a selective emitter. The Welsbach mantle in a common lantern is another example of an oxide selective emitter. Herein, we describe an alternative type of selective emitter, a selective metallic emitter. These metallic emitters are characterized by a spectral emissivity curve wherein the emissivity monotonically increases with shorter infrared wavelengths as is shown. The metal of curve "A", tungsten, typifies this class of selective metallic emitter's. In a thermophotovoltaic generator, a photovoltaic cell typically converts infrared radiation to electricity out to some cut-off wavelength. For example, Gallium Antimonide (GaSb) TPV cells respond out to 1.7 microns. The problem with gray body emitters is that they emit at all wavelengths. Therefore, a large fraction of the energy emitted will be outside of the response band of the TPV cell. The argument for the selective emitter is that, ideally, all the emitted energy can be in the cells response band. Unfortunately, rare earth oxide emitters are not ideal. In order to suppress the emissivity toward zero away from the select wavelength, the use of thin fiber's is necessary. This leads to a fragile emitter typical of a lantern mantle. Even given a thin ER-YAG emitter, the measured emissivity at the select wavelength of 1.5 microns has been reported to be 0.6 while the off wavelength background emissivity falls to only 0.2 at 5 microns. This gives a selectivity ratio of only 3. Another problem with a delta function selective emitter is its low power density at practical temperatures because of its narrow emission bandwidth. The concept of selectivity can be generalized by noting that we simply wish to maximize the ratio of in-cell-band power to out-of-cell-band power. Using this generalized selectivity concept and assuming a GaSb cell covered by a simple dielectric filter, we note that the emissivity selectivity ratio for tungsten is 0.3 (at 1.5 microns) / 0.07 (at 5 microns) = 4.3. In the folloy4ng sections, we note that the selective metallic emitters can be valuable in both radioisotope TPV generators in space and in hydrocarbon fired TPV generators here on earth.

Fraas, Lewis M.; Samaras, John E.; Avery, James E.; Ewell, Richard

1995-01-01

337

Can Compressed Sensing Be Applied To Dual-Polarimetric Weather Radars?  

NASA Astrophysics Data System (ADS)

The recovery of sparsely-sampled signals has long attracted considerable research interest in various fields such as reflection seismology, microscopy, and astronomy. Recently, such recovery techniques have been formalized as a sampling method called compressed sensing (CS) which uses few linear and non-adaptive measurements to reconstruct a signal that is sparse in a known domain. Many radar and remote sensing applications require efficient and rapid data acquisition. CS techniques have, therefore, enormous potential in dramatically changing the way the radar samples and processes data. A number of recent studies have investigated CS for radar applications with emphasis on point target radars, and synthetic aperture radar (SAR) imaging. CS radar holds the promise of compressing-while-sampling, and may yield simpler receiver hardware which uses low-rate ADCs and eliminates pulse compression/matched filter. The need of fewer measurements also implies that a CS radar may need smaller dwell times without significant loss of information. Finally, CS radar data could be used for improving the quality of low-resolution radar observations. In this study, we explore the feasibility of using CS for dual-polarimetric weather radars. In order to recover a signal in CS framework, two conditions must be satisfied: sparsity and incoherence. The sparsity of weather radar measurements can be modeled in several domains such as time, frequency, joint time-frequency domain, or polarimetric measurement domains. The condition of incoherence relates to the measurement process which, in a radar scenario, would imply designing an incoherent transmit waveform or an equivalent scanning strategy with an existing waveform. In this study, we formulate a sparse signal model for precipitation targets as observed by a polarimetric weather radar. The applicability of CS for such a signal model is then examined through simulations of incoherent measurements along with real weather data obtained from Iowa X-band Polarimetric (XPOL) radar units.

Mishra, K.; Kruger, A.; Krajewski, W. F.

2013-12-01

338

Determining Directional Emittance With An Infrared Imager  

NASA Technical Reports Server (NTRS)

Directional emittances of flat specimen of smooth-surfaced, electrically nonconductive material at various temperatures computed from measurements taken by infrared radiometric imager operating in conjunction with simple ancillary equipment. Directional emittances useful in extracting detailed variations of surface temperatures from infrared images of curved, complexly shaped other specimens of same material. Advantages: simplification of measurement procedure and reduction of cost.

Daryabeigi, Kamran; Alderfer, David W.; Wright, Robert E., Jr.; Puram, Chith K.

1994-01-01

339

Selective Emitter Pumped Rare Earth Laser  

NASA Technical Reports Server (NTRS)

A selective emitter pumped rare earth laser provides an additional type of laser for use in many laser applications. Rare earth doped lasers exist which are pumped with flashtubes or laser diodes. The invention uses a rare earth emitter to transform thermal energy input to a spectral band matching the absorption band of a rare earth in the laser in order to produce lasing.

Chubb, Donald L. (Inventor); Patton, Martin O. (Inventor)

2001-01-01

340

Considerations on data compression of synthetic aperture radar images  

NASA Technical Reports Server (NTRS)

This paper describes some analytical results relative to the effectiveness of applying data compression techniques for efficient transmission of synthetic aperture radar (SAR) signals and images. A Rayleigh target model is assumed in the analysis. It is also assumed that all surface reflectivity information is of interest and needs to be transmitted. Spectral characteristics of radar echo signals and processed images are analyzed. Analytical results generally indicate that due to the lack of high spatial correlation in the Rayleigh distributed radar surface reflectivity, application of data compression to SAR signals and images under the square difference fidelity criterion may be less effective than its application to images obtained using incoherent illumination. On the other hand, if certain random variations in radar images are considered as undesirable, substantial compression ratio may be achieved by removing such variations.

Wu, C.

1976-01-01

341

High-resolution three-dimensional imaging radar  

NASA Technical Reports Server (NTRS)

A three-dimensional imaging radar operating at high frequency e.g., 670 GHz, is disclosed. The active target illumination inherent in radar solves the problem of low signal power and narrow-band detection by using submillimeter heterodyne mixer receivers. A submillimeter imaging radar may use low phase-noise synthesizers and a fast chirper to generate a frequency-modulated continuous-wave (FMCW) waveform. Three-dimensional images are generated through range information derived for each pixel scanned over a target. A peak finding algorithm may be used in processing for each pixel to differentiate material layers of the target. Improved focusing is achieved through a compensation signal sampled from a point source calibration target and applied to received signals from active targets prior to FFT-based range compression to extract and display high-resolution target images. Such an imaging radar has particular application in detecting concealed weapons or contraband.

Cooper, Ken B. (Inventor); Chattopadhyay, Goutam (Inventor); Siegel, Peter H. (Inventor); Dengler, Robert J. (Inventor); Schlecht, Erich T. (Inventor); Mehdi, Imran (Inventor); Skalare, Anders J. (Inventor)

2010-01-01

342

Goldstone Solar System Radar Waveform Generator  

NASA Technical Reports Server (NTRS)

Due to distances and relative motions among the transmitter, target object, and receiver, the time-base between any transmitted and received signal will undergo distortion. Pre-distortion of the transmitted signal to compensate for this time-base distortion allows reception of an undistorted signal. In most radar applications, an arbitrary waveform generator (AWG) would be used to store the pre-calculated waveform and then play back this waveform during transmission. The Goldstone Solar System Radar (GSSR), however, has transmission durations that exceed the available memory storage of such a device. A waveform generator capable of real-time pre-distortion of a radar waveform to a given time-base distortion function is needed. To pre-distort the transmitted signal, both the baseband radar waveform and the RF carrier must be modified. In the GSSR, this occurs at the up-conversion mixing stage to an intermediate frequency (IF). A programmable oscillator (PO) is used to generate the IF along with a time-varying phase component that matches the time-base distortion of the RF carrier. This serves as the IF input to the waveform generator where it is mixed with a baseband radar waveform whose time-base has been distorted to match the given time-base distortion function producing the modulated IF output. An error control feedback loop is used to precisely control the time-base distortion of the baseband waveform, allowing its real-time generation. The waveform generator produces IF modulated radar waveforms whose time-base has been pre-distorted to match a given arbitrary function. The following waveforms are supported: continuous wave (CW), frequency hopped (FH), binary phase code (BPC), and linear frequency modulation (LFM). The waveform generator takes as input an IF with a time varying phase component that matches the time-base distortion of the carrier. The waveform generator supports interconnection with deep-space network (DSN) timing and frequency standards, and is controlled through a 1 Gb/s Ethernet UDP/IP interface. This real-time generation of a timebase distorted radar waveform for continuous transmission in a planetary radar is a unique capability.

Quirk, Kevin J.; Patawaran, Ferze D.; Nguyen, Danh H.; Nguyen, Huy

2012-01-01

343

Directional emittance surface measurement system and process  

NASA Technical Reports Server (NTRS)

Apparatus and process for measuring the variation of directional emittance of surfaces at various temperatures using a radiometric infrared imaging system. A surface test sample is coated onto a copper target plate provided with selective heating within the desired incremental temperature range to be tested and positioned onto a precision rotator to present selected inclination angles of the sample relative to the fixed positioned and optically aligned infrared imager. A thermal insulator holder maintains the target plate on the precision rotator. A screen display of the temperature obtained by the infrared imager, and inclination readings are provided with computer calculations of directional emittance being performed automatically according to equations provided to convert selected incremental target temperatures and inclination angles to relative target directional emittance values. The directional emittance of flat black lacquer and an epoxy resin measurements obtained are in agreement with the predictions of the electromagnetic theory and with directional emittance data inferred from directional reflectance measurements made on a spectrophotometer.

Puram, Chith K. (Inventor); Daryabeigi, Kamran (Inventor); Wright, Robert (Inventor); Alderfer, David W. (Inventor)

1994-01-01

344

Emittance measurements of the CLIO electron beam  

NASA Astrophysics Data System (ADS)

We have designed a setup to measure the transverse emittance at the CLIO accelerator exit, based on the "3 gradients" method. The beam transverse size is measured simply by scanning it with a steering coil across a fixed jaw and recording the transmitted current, at various quadrupole strengths. A code then performs a complete calculation of the emittance using the transfer matrix of the quadrupole instead of the usual classical lens approximation. We have studied the influence of various parameters on the emittance: Magnetic field on the e-gun and the peak current. We have also improved a little the emittance by replacing a mismatched pipe between the buncher and accelerating section to avoid wake-field effects; The resulting improvements of the emittance have led to an increase in the FEL emitted power.

Chaput, R.; Devanz, G.; Joly, P.; Kergosien, B.; Lesrel, J.

1997-02-01

345

Microlensless interdigitated photoconductive terahertz emitters.  

PubMed

We report here fabrication of interdigitated photoconductive antenna (iPCA) terahertz (THz) emitters based on plasmonic electrode design. Novel design of this iPCA enables it to work without microlens array focusing, which is otherwise required for photo excitation of selective photoconductive regions to avoid the destructive interference of emitted THz radiation from oppositely biased regions. Benefit of iPCA over single active region PCA is, photo excitation can be done at larger area hence avoiding the saturation effect at higher optical excitation density. The emitted THz radiation power from plasmonic-iPCAs is ~2 times more than the single active region plasmonic PCA at 200 mW optical excitation, which will further increase at higher optical powers. This design is expected to reduce fabrication cost of photoconductive THz sources and detectors. PMID:25835910

Singh, Abhishek; Prabhu, S S

2015-01-26

346

Positron emitter labeled enzyme inhibitors  

SciTech Connect

This invention involves a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide inactivators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography.

Fowler, J.S.; MacGregor, R.R.; Wolf, A.P.; Langstrom, B.

1990-04-03

347

Positron emitter labeled enzyme inhibitors  

DOEpatents

This invention involves a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide inactivators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography.

Fowler, Joanna S. (Bellport, NY); MacGregor, Robert R. (Sag Harbor, NY); Wolf, Alfred P. (Setauket, NY); Langstrom, Bengt (Upsala, SE)

1990-01-01

348

Positron emitter labeled enzyme inhibitors  

DOEpatents

This invention involved a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide in activators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography. 2 figs.

Fowler, J.S.; MacGregor, R.R.; Wolf, A.P.

1987-05-22

349

Java Radar Analysis Tool  

NASA Technical Reports Server (NTRS)

Java Radar Analysis Tool (JRAT) is a computer program for analyzing two-dimensional (2D) scatter plots derived from radar returns showing pieces of the disintegrating Space Shuttle Columbia. JRAT can also be applied to similar plots representing radar returns showing aviation accidents, and to scatter plots in general. The 2D scatter plots include overhead map views and side altitude views. The superposition of points in these views makes searching difficult. JRAT enables three-dimensional (3D) viewing: by use of a mouse and keyboard, the user can rotate to any desired viewing angle. The 3D view can include overlaid trajectories and search footprints to enhance situational awareness in searching for pieces. JRAT also enables playback: time-tagged radar-return data can be displayed in time order and an animated 3D model can be moved through the scene to show the locations of the Columbia (or other vehicle) at the times of the corresponding radar events. The combination of overlays and playback enables the user to correlate a radar return with a position of the vehicle to determine whether the return is valid. JRAT can optionally filter single radar returns, enabling the user to selectively hide or highlight a desired radar return.

Zaczek, Mariusz P.

2005-01-01

350

Phased-array radars  

Microsoft Academic Search

The operating principles, technology, and applications of phased-array radars are reviewed and illustrated with diagrams and photographs. Consideration is given to the antenna elements, circuitry for time delays, phase shifters, pulse coding and compression, and hybrid radars combining phased arrays with lenses to alter the beam characteristics. The capabilities and typical hardware of phased arrays are shown using the US

Eli Brookner

1985-01-01

351

Radar image interpretability analysis  

Microsoft Academic Search

The utility of radar images with respect to trained image interpreter ability to identify, classify and detect specific terrain features (linear, natural area, complex area features, and individual man-made features) was qualitatively determined. Further, radar images were evaluated with respect to their utility for determining vehicle movement potential and the level of activity within the test areas. Because there are

V. S. Frost; J. A. Stiles; J. C. Holtzman

1981-01-01

352

Noncooperative rendezvous radar system  

NASA Technical Reports Server (NTRS)

A fire control radar system was developed, assembled, and modified. The baseline system and modified angle tracking system are described along with the performance characteristics of the baseline and modified systems. Proposed changes to provide additional techniques for radar evaluation are presented along with flight test data.

1974-01-01

353

Low Emittance Electron Beam Studies  

SciTech Connect

We have studied the properties of a low emittance electron beam produced by laser pulses incident onto an rf gun photocathode. The experiments were carried out at the A0 photoinjector at Fermilab. Such beam studies are necessary for fixing the design of new Linear Colliders as well as for the development of Free Electron Lasers. An overview of the A0 photoinjector is given in Chapter 1. In Chapter 2 we describe the A0 photoinjector laser system. A stable laser system is imperative for reliable photoinjector operation. After the recent upgrade, we have been able to reach a new level of stability in the pulse-to-pulse fluctuations of the pulse amplitude, and of the temporal and transverse profiles. In Chapter 3 we present a study of transverse emittance versus the shape of the photo-cathode drive-laser pulse. For that purpose a special temporal profile laser shaping device called a pulse-stacker was developed. In Chapter 4 we discuss longitudinal beam dynamics studies using a two macro-particle bunch; this technique is helpful in analyzing pulse compression in the magnetic chicane, as well as velocity bunching effects in the rf-gun and the 9-cell accelerating cavity. In Chapter 5 we introduce a proposal for laser acceleration of electrons. We have developed a laser functioning on the TEM*{sub 01} mode, a mode with a longitudinal electric field component which is suitable for such a process. Using this technique at energies above 40 MeV, one would be able to observe laser-based acceleration.

Tikhoplav, Rodion; /Rochester U.

2006-04-01

354

Looking at Radar Images  

NSDL National Science Digital Library

These activities pertain to the value of the different types of images, including a false color mosaic, a Compressed Stokes image, a vegetation map and key, and various ground photographs. Students are given specific directions on how to decide what features of a radar image indicate such structures as upland forest, clear-cut areas, and roads. In a second activity, students look at the radar images to see if they can produce a vegetation map similar to the one they have been given. The third activity introduces 15 Decade Volcanoes that pose a particular threat to humans. Using the Decade Volcanoes as examples, students view radar images of volcanoes that occur around the world. The final exercise is aimed at helping students distinguish the differences between radar image data and visible photographs. Students will look at radar data and photographs of three sites taken by the astronauts.

355

Operational Monitoring of Weather Radar Receiving Chain Using the Sun IWAN HOLLEMAN  

E-print Network

Operational Monitoring of Weather Radar Receiving Chain Using the Sun IWAN HOLLEMAN Royal, is presented. The ``online'' method is entirely based on the analysis of sun signals in the polar volume data- termining the weather radar antenna pointing at low elevations using sun signals, and it is suited

Stoffelen, Ad

356

5. VIEW EAST, height finder radar towers, radar tower (unknown ...  

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

5. VIEW EAST, height finder radar towers, radar tower (unknown function), prime search radar tower, operations building, and central heating plant - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

357

4. VIEW NORTHEAST, radar tower (unknown function), prime search radar ...  

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

4. VIEW NORTHEAST, radar tower (unknown function), prime search radar tower, emergency power building, and height finder radar tower - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

358

Ultra-wideband short-pulse radar with range accuracy for short range detection  

DOEpatents

An ultra-wideband (UWB) radar transmitter apparatus comprises a pulse generator configured to produce from a sinusoidal input signal a pulsed output signal having a series of baseband pulses with a first pulse repetition frequency (PRF). The pulse generator includes a plurality of components that each have a nonlinear electrical reactance. A signal converter is coupled to the pulse generator and configured to convert the pulsed output signal into a pulsed radar transmit signal having a series of radar transmit pulses with a second PRF that is less than the first PRF.

Rodenbeck, Christopher T; Pankonin, Jeffrey; Heintzleman, Richard E; Kinzie, Nicola Jean; Popovic, Zorana P

2014-10-07

359

Cooperative control of MAVs for a hidden emitter localization  

NASA Astrophysics Data System (ADS)

This paper provides a summary of the development of a three state machine-based cooperative control algorithm that is applied to multiple Unmanned Aerial Vehicles (UAVs) or Micro-Aerial Vehicles (MAVs) control. We use MAVs for cooperative search of a hidden electromagnetic source (emitter) in a controlled environment. MAVs are equipped with wireless sensor nodes capable of sensing an electromagnetic (EM) field around them. Simultaneous control and sensing capabilities of these MAVs are presented. The algorithm uses a three-state machine to control the MAVs during the search process. The first state is a decentralized cooperative search that allows MAVs to obtain information about the environment and detect EM emissions from the target. The second state implements a gradient descent algorithm in which the MAVs converge towards the target based on the received signal strength, while still maintaining a proximal distance from each other. MAVs are positioned at the optimal distance of the detected EM source before fine-tuning of the emitter localization is carried out. The third state incorporates a technique called Position-Adaptive Direction Finding (PADF), where the MAVs adapt their positions in order to further improve localization of a hidden emitter using an estimated path loss exponent as a feedback. We present simulation and experimental data that illustrate the proposed approach.

Gates, Miguel; Selmic, Rastko; Ordonez, Raul

2012-06-01

360

Doppler radar imaging of spherical planetary surfaces  

NASA Technical Reports Server (NTRS)

This paper describes a technique for using echo power-spectra for making radar images of spherical planetary targets. In developing the Doppler-radar imaging system, the target's reflectivity distribution is expanded in a truncated spherical harmonic series; the distribution of echo power in rotational phase and the Doppler frequency are obtained in form of a system of linear equations which express the echo spectra as functions of the series coefficients. To estimate the coefficients from an observed phase-Doppler distribution, the inversion is cast as a least-squares problem, and is solved using singular value decompositions, yielding a linear imaging system which can be fully characterized by its impulse response as a function of latitude. Simulations were designed and used to explore the capabilities of Doppler radar imaging, and the sensitivity of imaging to such factors as subradar altitude coverage and signal-to-noise ratio was investigated.

Hudson, R. Scott; Ostro, Steven J.

1990-01-01

361

Delineate subsurface structures with ground penetrating radar  

SciTech Connect

High resolution ground penetrating radar (GPR) surveys were conducted at the Savannah River Site in South Carolina in late 1991 to demonstrate the radar techniques in imaging shallow utility and soil structures. Targets of interest at two selected sites, designated as H- and D-areas, were a buried backfilled trench, buried drums, geologic stratas, and water table. Multiple offset 2-D and single offset 3-D survey methods were used to acquire high resolution radar data. This digital data was processed using standard seismic processing software to enhance signal quality and improve resolution. Finally, using a graphics workstation, the 3D data was interpreted. In addition, a small 3D survey was acquired in The Woodlands, Texas, with very dense spatial sampling. This data set adequately demonstrated the potential of this technology in imaging subsurface features.

Wyatt, D.E. [Westinghouse Savannah River Co., Aiken, SC (United States); Hu, L.Z. [New Wave Technology, Houston, TX (United States); Ramaswamy, M. [Houston Advanced Research Center, Woodlands, TX (United States); Sexton, B.G. [Microseeps, Inc., Pittsburgh, PA (United States)

1992-10-01

362

TRMS, a mobile 3D-radar  

NASA Astrophysics Data System (ADS)

Development of West Germany's TRMS three-dimensional mobile radar system began in 1972 and progressed to current production status through the development and extensive testing of two prototypes. TRMS, which operates in G-band and is transported aboard two 15-ton trucks (one for the radar apparatus, the other for signal processing and display) with cross-country capability, was designed to detect small targets over the full range of altitudes. It exhibits high resistance against both natural and man-made interference, and has selectable operational modes that allow adaptation to changes in operational environment. Also developed is TRML, a single-vehicle, medium-range, two-dimensional G-band radar incorporating many TRMS equipment modules.

Gerlitzki, W. J.

363

Generic evaluation tracker database for OTH radar  

NASA Astrophysics Data System (ADS)

This paper provides a real world target and clutter model for evaluation of radar signal processing algorithms. The procedure is given for target and clutter data collection which is then followed by the equalization and superposition method. We show how the model allows one to vary the target signal to clutter noise ratio so that system performance may be assessed over a wide range of target amplitudes, i.e. detection probability versus target signal to noise ratio. Three candidate pre-track algorithms are evaluated and compared using this model as input in conjunction with an advanced tracker algorithm as a post processor. Data used for the model represents airborne traffic operating over the body of water bounded by North, Central, and South America. The processors relate to the deployment of Over the Horizon Radar for drug interdiction. All the components of this work, model as well as the processors, are in software.

Flanders, Lorraine E.; Hartnett, Michael P.; Vannicola, Vincent C.

1999-10-01

364

Progress reports for October 1994 -- Joint UK/US Radar Program  

SciTech Connect

This report gives the principle investigator, objectives, recent accomplishments, milestones for reporting period, expected milestones for ensuing period, other issues and planned expenditures for each of the following programs: airborne RAR/SAR; radar data processor; ground-based SAR signal processing workstation; static airborne radar; multi-aperture space-time array radar; radar field experiments; data analysis and detection theory; management; E-2C radar data analysis; modeling and analysis; current meter array; UCSB wave tank; stratified flow facility; and IR sensor system. Finally the budget status is given.

Twogood, R.E.; Brase, J.M.; Mantrom, D.D.; Chambers, D.H.; Robey, H.F.

1994-11-18

365

Progress reports for period November 1--30, 1994 -- Joint UK/US Radar Program  

SciTech Connect

This report gives the principle investigator, objectives, recent accomplishments, milestones for reporting period, expected milestones for ensuing period, other issues and planned expenditures for the following programs: airborne RAR/SAR; radar data processor; ground-based SAR signal processing workstation; static airborne radar; multi-aperture space-time array radar; radar field experiments; data analysis and detection theory; management; E-2C radar data analysis;modeling and analysis; current meter array; UCSB wave tank; stratified flow facility; and IR sensor system. Budget status is also given.

Twogood, R.E.; Brase, J.M.; Mantrom, D.D.; Chambers, D.H.; Robey, H.F.

1994-12-19

366

Compliance with High-Intensity Radiated Fields Regulations - Emitter's Perspective  

NASA Technical Reports Server (NTRS)

NASA's Deep Space Network (DSN) uses high-power transmitters on its large antennas to communicate with spacecraft of NASA and its partner agencies. The prime reflectors of the DSN antennas are parabolic, at 34m and 70m in diameter. The DSN transmitters radiate Continuous Wave (CW) signals at 20 kW - 500 kW at X-band and S-band frequencies. The combination of antenna reflector size and high frequency results in a very narrow beam with extensive oscillating near-field pattern. Another unique feature of the DSN antennas is that they (and the radiated beam) move mostly at very slow sidereal rate, essentially identical in magnitude and at the opposite direction of Earth rotation.The DSN is in the process of revamping its documentation to provide analysis of the High Intensity Radiation Fields (HIRF) environment resulting from radio frequency radiation from DSN antennas for comparison to FAA regulations regarding certification of HIRF protection as outlined in the FAA regulations on HIRF protection for aircraft electrical and electronic systems (Title 14, Code of Federal Regulations (14 CFR) [section sign][section sign] 23.1308, 25.1317, 27.1317, and 29.1317).This paper presents work done at JPL, in consultation with the FAA. The work includes analysis of the radiated field structure created by the unique DSN emitters (combination of transmitters and antennas) and comparing it to the fields defined in the environments in the FAA regulations. The paper identifies areas that required special attention, including the implications of the very narrow beam of the DSN emitters and the sidereal rate motion. The paper derives the maximum emitter power allowed without mitigation and the mitigation zones, where required.Finally, the paper presents summary of the results of the analyses of the DSN emitters and the resulting DSN process documentation.

Statman, Joseph; Jamnejad, Vahraz; Nguyen, Lee

2012-01-01

367

Polariton-enhanced emittance of metallic-dielectric multilayer structures for selective thermal emitters  

NASA Astrophysics Data System (ADS)

This study proposes a tungsten grating structure with SiO2-W-SiO2 multilayer films on a tungsten substrate as a thermal emitter for transverse-magnetic waves in a broad spectral region. The rigorous coupled-wave analysis method is employed to analyze the spectral emittance. Three close-to-unity peaks on the emittance spectrum lift the emittance in the wavelength range from 0.7 ?m to 2.0 ?m for the proposed thermal emitter. To quantify the applicability of the proposed emitter, parametric studies are performed regarding the effects of grating geometrical parameters, emission angle, metallic/dielectric layer thicknesses, and mismachining tolerance. The normal emittance of the proposed emitter is shown to be wavelength-selective and direction-insensitive. The mechanisms of excitations of surface plasmon polariton (SPP), gap plasmon polariton (GPP), and magnetic polariton (MP) in the multilayer structure are elucidated to evaluate their contributions on the emittance under different conditions. The results provide a useful reference to design and optimize selective thermal emitters with excellent performance.

Shuai, Yong; Tan, Heping; Liang, Yingchun

2014-03-01

368

A solid state low pulse power ground surveillance radar  

NASA Astrophysics Data System (ADS)

The use of high-duty-ratio transmissions improves the efficiency and economy of solid state transmitter power amplifiers, while simultaneously reducing the detectability of a radar by conventional electronic surveillance receivers. A composite waveform, consisting of two orthogonally coded pulses radiated within the same pulse repetition interval, offers a combination of high transmission duty ratio and a pulse repetition rate low enough to avoid range ambiguity. Used with solid-state-transmitters, low-sidelobe antennas, and modern signal-processing techniques, this waveform provides the basis for a class of short-to-medium-range radars that combine good clutter discrimination with high survivability in a radar countermeasures environment. Following a short discussion of radar detectability and a description of the orthogonally coded pulse waveform, this paper outlines the design features of a practical ground surveillance radar that is being developed to evaluate these concepts.

McKillop, A.

369

Development and characterization analysis of a radar polarimeter  

NASA Technical Reports Server (NTRS)

The interaction of electromagnetic waves with natural earth surface was of interest for many years. A particular area of interest in controlled remote sensing experiments is the phenomena of depolarization. The development stages of the radar system are documented. Also included are the laboratory procedures which provides some information about the specifications of the system. The radar system developed is termed the Radar Polarimeter System. A better insight of the operation of the RPS in terms of the newly developed technique--synthetic aperture radar system is provided. System performance in tems of radar cross section, in terms of power, and in terms of signal to noise ratio are also provided. In summary, an overview of the RPS in terms of its operation and design as well as how it will perform in the field is provided.

Bong, S.; Blanchard, A. J.

1983-01-01

370

162 IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 33, NO. 1, JANUARY 1995 Behavior of the Ocean Radar Cross-  

E-print Network

of the Ocean Radar Cross- Section at Low Incidence, Observed in the Vicinity of the Gulf Stream Danikle Hauser to examine the behaviour of the radar cross-sectionU' versus incidence @ and azimuth 4. Although, considerableeffort has been devoted 0to the understanding of the behaviour of radar signal backscattered from

Miami, University of

371

Use and Interpretation of Radar  

NSDL National Science Digital Library

This undergraduate meteorology tutorial from Texas A&M University discusses the basic principles of operation of weather radars, describes how to interpret radar mosaics, and discusses the use of radar in weather forecasting. Students learn the relationship between range and elevation and how to use radar images and mosaics in short-range forecasting.

John Nielsen-Gammon

1996-01-01

372

Multinozzle Emitter Arrays for Nanoelectrospray Mass Spectrometry  

PubMed Central

Mass spectrometry (MS) is the enabling technology for proteomics and metabolomics. However, dramatic improvements in both sensitivity and throughput are still required to achieve routine MS-based single cell proteomics and metabolomics. Here, we report the silicon-based monolithic multinozzle emitter array (MEA), and demonstrate its proof-of-principle applications in high-sensitivity and high-throughput nanoelectrospray mass spectrometry. Our MEA consists of 96 identical 10-nozzle emitters in a circular array on a 3-inch silicon chip. The geometry and configuration of the emitters, the dimension and number of the nozzles, and the micropillar arrays embedded in the main channel, can be systematically and precisely controlled during the microfabrication process. Combining electrostatic simulation and experimental testing, we demonstrated that sharpened-end geometry at the stem of the individual multinozzle emitter significantly enhanced the electric fields at its protruding nozzle tips, enabling sequential nanoelectrospray for the high-density emitter array. We showed that electrospray current of the multinozzle emitter at a given total flow rate was approximately proportional to the square root of the number of its spraying-nozzles, suggesting the capability of high MS sensitivity for multinozzle emitters. Using a conventional Z-spray mass spectrometer, we demonstrated reproducible MS detection of peptides and proteins for serial MEA emitters, achieving sensitivity and stability comparable to the commercial capillary emitters. Our robust silicon-based MEA chip opens up the possibility of a fully-integrated microfluidic system for ultrahigh-sensitivity and ultrahigh-throughput proteomics and metabolomics. PMID:21728281

Mao, Pan; Wang, Hung-Ta; Yang, Peidong; Wang, Daojing

2011-01-01

373

Multinozzle emitter arrays for nanoelectrospray mass spectrometry.  

PubMed

Mass spectrometry (MS) is the enabling technology for proteomics and metabolomics. However, dramatic improvements in both sensitivity and throughput are still required to achieve routine MS-based single cell proteomics and metabolomics. Here, we report the silicon-based monolithic multinozzle emitter array (MEA) and demonstrate its proof-of-principle applications in high-sensitivity and high-throughput nanoelectrospray mass spectrometry. Our MEA consists of 96 identical 10-nozzle emitters in a circular array on a 3 in. silicon chip. The geometry and configuration of the emitters, the dimension and number of the nozzles, and the micropillar arrays embedded in the main channel can be systematically and precisely controlled during the microfabrication process. Combining electrostatic simulation and experimental testing, we demonstrated that sharpened-end geometry at the stem of the individual multinozzle emitter significantly enhanced the electric fields at its protruding nozzle tips, enabling sequential nanoelectrospray for the high-density emitter array. We showed that electrospray current of the multinozzle emitter at a given total flow rate was approximately proportional to the square root of the number of its spraying-nozzles, suggesting the capability of high MS sensitivity for multinozzle emitters. Using a conventional Z-spray mass spectrometer, we demonstrated reproducible MS detection of peptides and proteins for serial MEA emitters, achieving sensitivity and stability comparable to the commercial capillary emitters. Our robust silicon-based MEA chip opens up the possibility of a fully integrated microfluidic system for ultrahigh-sensitivity and ultrahigh-throughput proteomics and metabolomics. PMID:21728281

Mao, Pan; Wang, Hung-Ta; Yang, Peidong; Wang, Daojing

2011-08-01

374

Narrowband terahertz emitters using metamaterial films.  

PubMed

In this article we report on metamaterial-based narrowband thermal terahertz (THz) emitters with a bandwidth of about 1 THz. Single band emitters designed to radiate in the 4 to 8 THz range were found to emit as high as 36 W/m(2) when operated at 400 °C. Emission into two well-separated THz bands was also demonstrated by using metamaterial structures featuring more complex unit cells. Imaging of heated emitters using a microbolometer camera fitted with THz optics clearly showed the expected higher emissivity from the metamaterial structure compared to low-emissivity of the surrounding aluminum. PMID:23037226

Alves, Fabio; Kearney, Brian; Grbovic, Dragoslav; Karunasiri, Gamani

2012-09-10

375

Thermophotovoltaic emitter material selection and design  

SciTech Connect

Thermophotovoltaics (TPV) is a potentially attractive direct energy conversion technology. It reduces the need for complex machinery with moving parts and maintenance. TPV generators can be run from a variety of heat sources including waste heat for smaller scale operations. The US Naval Academy`s goal was to build a small experimental thermophotovoltaic generator powered by combustion gases from a General Electric T-58 helicopter gas turbine. The design of the generator imposes material limitations that directly affect emitter and structural materials selection. This paper details emitter material goals and requirements, and the methods used to select suitable candidate emitter materials for further testing.

Saxton, P.C.; Moran, A.L.; Harper, M.J.; Lindler, K.W. [Naval Academy, Annapolis, MD (United States)

1997-07-01

376

Spaceborne meteorological radar studies  

NASA Technical Reports Server (NTRS)

Various radar designs and methods are studied for the estimation of rainfall parameters from space. An immediate goal is to support the development of the spaceborne radar that has been proposed for the Tropical Rain Measuring Mission (TRMM). The effort is divided into two activities: a cooperative airborne rain measuring experiment with the Radio Research Laboratory of Japan (RRL), and the modelling of spaceborne weather radars. An airborne rain measuring experiment was conducted at Wallops Flight Facility in 1985 to 1986 using the dual-wavelength radar/radiometer developed by RRL. The data are presently being used to test a number of methods that are relevant to spaceborne weather radars. An example is shown of path-averaged rain rates as estimated from three methods: the standard reflectivity rain rate method (Z-R), a dual-wavelength method, and a surface reference method. The results from the experiment shows for the first time the feasibility of using attenuation methods from space. The purposes of the modelling are twofold: to understand in a quantitative manner the relationships between a particular radar design and its capability for estimating precipitation parameters and to help devise and test new methods. The models are being used to study the impact of various TRMM radar designs on the accuracy of rain rate estimation as well as to test the performance of range-profiling algorithms, the mirror-image method, and some recently devised graphical methods for the estimation of the drop size distribution.

Meneghini, R.

1988-01-01

377

Radar Remote Sensing  

NASA Technical Reports Server (NTRS)

This lecture was just a taste of radar remote sensing techniques and applications. Other important areas include Stereo radar grammetry. PolInSAR for volumetric structure mapping. Agricultural monitoring, soil moisture, ice-mapping, etc. The broad range of sensor types, frequencies of observation and availability of sensors have enabled radar sensors to make significant contributions in a wide area of earth and planetary remote sensing sciences. The range of applications, both qualitative and quantitative, continue to expand with each new generation of sensors.

Rosen, Paul A.

2012-01-01

378

Optically isolated signal coupler with linear response  

DOEpatents

An optocoupler for isolating electrical signals that translates an electrical input signal linearly to an electrical output signal. The optocoupler comprises a light emitter, a light receiver, and a light transmitting medium. The light emitter, preferably a blue, silicon carbide LED, is of the type that provides linear, electro-optical conversion of electrical signals within a narrow wavelength range. Correspondingly, the light receiver, which converts light signals to electrical signals and is preferably a cadmium sulfide photoconductor, is linearly responsive to light signals within substantially the same wavelength range as the blue LED.

Kronberg, James W. (Aiken, SC)

1994-01-01

379

Interpretation of MST radar returns from clear air  

NASA Technical Reports Server (NTRS)

The nature of the scattering and reflection mechanisms that give rise to the MST radar echoes from the clear air is essential in the correct interpretation of the data about winds, waves, turbulence and stability in the atmosphere. There are two main aspects: the nature of the targets the radar sees and their generation mechanisms; and the signatures of the radar signals returned from the different targets. Volume scatterings from isotropic or anisotropic turbulence, and partial reflections from horizontally stratified, sharp refractive index gradients are believed the main contributors to radar echoes. Combined effects from all the mechanisms probably produce the observed data. The signature of the echo signals for these different scatterers under realistic experimental conditions should be studied. It is hoped from these studies, the nature of the targets can be better understood, and related to atmospheric dynamic processes.

Liu, C. H.

1983-01-01

380

Emitters of N-photon bundles  

PubMed Central

Controlling the ouput of a light emitter is one of the basic tasks of photonics, with landmarks such as the laser and single-photon sources. The development of quantum applications makes it increasingly important to diversify the available quantum sources. Here, we propose a cavity QED scheme to realize emitters that release their energy in groups, or “bundles” of N photons, for integer N. Close to 100% of two-photon emission and 90% of three-photon emission is shown to be within reach of state of the art samples. The emission can be tuned with system parameters so that the device behaves as a laser or as a N-photon gun. The theoretical formalism to characterize such emitters is developed, with the bundle statistics arising as an extension of the fundamental correlation functions of quantum optics. These emitters will be useful for quantum information processing and for medical applications. PMID:25013456

Muñoz, C. Sánchez; del Valle, E.; Tudela, A. González; Müller, K.; Lichtmannecker, S.; Kaniber, M.; Tejedor, C.; Finley, J.J.; Laussy, F.P.

2014-01-01

381

Arc-textured high emittance radiator surfaces  

NASA Technical Reports Server (NTRS)

High emittance radiator surfaces are produced by arc-texturing. This process produces such a surface on a metal by scanning it with a low voltage electric arc from a carbon electrode in an inert environment.

Banks, Bruce A. (inventor)

1991-01-01

382

Emittance growth in linear induction accelerators  

E-print Network

The Dual-Axis Radiographic Hydrotest (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. Radiographic resolution is determined by the size of the source spot, and beam emittance is the ultimate limitation to spot size. On the DARHT Axis-II LIA we measure an emittance higher than predicted by theoretical simulations, and even though this axis produces sub-millimeter source spots, we are exploring ways to improve the emittance. Some of the possible causes for the discrepancy have been investigated using particle-in-cell (PIC) codes, although most of these are discounted based on beam measurements. The most likely source of emittance growth is a mismatch of the beam to the magnetic transport, which can cause beam halo.

Ekdahl, C A; Schulze, M E; Carlson, C A; Frayer, D K; Mostrum, C; Thoma, C H

2014-01-01

383

Electrospray emitters For diffusion vacuum pumps  

E-print Network

Following similar principles as regular diffusion vacuum pumps, an electrospray emitter is set to produce a jet of charged particles that will drag air molecules out of a volume. To be a feasible concept, the emitted ...

Diaz Gómez Maqueo, Pablo (Pablo Ly)

2011-01-01

384

Optimal Selectionof Binary Codes for Pulse Compression in Surveillance Radar  

NASA Astrophysics Data System (ADS)

The papers aim to make a comparative study of binary phase codes in Radar pulse compression. Pulse compression allows radar to use long waveforms in order to obtain high energy and simultaneously achieve the resolution of a short pulse by internal modulation of the longpulse. This technique increases signal bandwidth through frequency or phase coding. This paper does a comparative analysis of binary codes based on the simulation results of their autocorrelation function and identifies 13 bit Barker code as the most optimal binary code for surveillance radar

Sethi, Sonia

2013-03-01

385

Experimental phased array radar ELRA with extended flexibility  

NASA Astrophysics Data System (ADS)

An update of a phased array radar research project with the experimental system ELRA (electronic steerable radar) is given with respect to the extended and improved possibilities for performing measurements and evaluations for different types of radar operation. The variability of waveforms for solid-state transmitters is described. Flexible control of multifunction operation with various search and localization tasks is achieved with a network of microcomputers. Different means of signal processing are used for target detection and estimation. The active receiving array is divided into subarrays, and offers digital beamforming for pattern shaping and adaptive jammer suppression. Experimental results are presented.

Groeger, I.; Sander, W.; Wirth, W.-D.

1990-11-01

386

Energy efficiency of electron plasma emitters  

SciTech Connect

Electron emission influence from gas-discharge plasma on plasma emitter energy parameters is considered. It is shown, that electron emission from plasma is accompanied by energy contribution redistribution in the gas-discharge from plasma emitter supplies sources-the gas-discharge power supply and the accelerating voltage power supply. Some modes of electron emission as a result can be realized: 'a probe measurements mode,' 'a transitive mode,' and 'a full switching mode.'.

Zalesski, V. G., E-mail: V.Zalesski@mail.ru [Polotsk State University (Belarus)

2011-12-15

387

Alpha-emitters for medical therapy workshop  

SciTech Connect

A workshop on ``Alpha-Emitters for Medical Therapy`` was held May 30-31, 1996 in Denver Colorado to identify research goals and potential clinical needs for applying alpha-particle emitters and to provide DOE with sufficient information for future planning. The workshop was attended by 36 participants representing radiooncology, nuclear medicine, immunotherapy, radiobiology, molecular biology, biochemistry, radiopharmaceutical chemistry, dosimetry, and physics. This report provides a summary of the key points and recommendations arrived at during the conference.

Feinendegen, L.E.; McClure, J.J.

1996-12-31

388

GMTI MIMO radar  

E-print Network

Multiple-input multiple-output (MIMO) extensions to radar systems enable a number of advantages compared to traditional approaches. These advantages include improved angle estimation and target detection. In this paper, ...

Bliss, Daniel W., Jr.

389

Caribbean Radar Products  

NSDL National Science Digital Library

This module provides examples of radar imagery from various locations in the Caribbean to demonstrate the different types of images available. Also, examples of different meteorological and non meteorological features are presented to show features seen in island locations.

COMET

2013-12-31

390

Imaging with Radar  

NSDL National Science Digital Library

This interactive activity from NOVA features synthetic aperture radar (SAR), which uses radio waves to create high-quality images. Examine SAR images of Washington, D.C., and learn about this technology's unique advantages.

WGBH Educational Foundation

2004-01-29

391

Multipolarization Radar Images for Geologic Mapping and Vegetation Discrimination  

Microsoft Academic Search

The NASA\\/JPL airborne synthetic aperture radar system produces radar image data simultaneously in four linear polarizations (HH, VV, VH, HV) at 24.6-cm wavelength (L-band), with 10-m resolution, across a swath width of approximately 10 km. The signal data are recorded optically and digitally and annotated in each of the channels to facilitate a completely automated digital correlation. Both standard amplitude,

Diane Evans; Tom Farr; J. P. Ford; Thomas Thompson; C. L. Werner

1986-01-01

392

Doppler Radar Technology  

NSDL National Science Digital Library

This resource provides an introduction to the function and uses of the The National Weather Service's (NWS) Weather Surveillance Doppler Radar (WSR-88D). Topics include the components of the system, an overview of the products and overlays the system creates, and some example images with captions explaining what is being shown. There are also links to radar meteorology tutorials and to information on training to use the system and interpret its imagery.

393

Downhole pulse radar  

DOEpatents

A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole. 7 figs.

Chang, Hsi-Tien

1987-09-28

394

Downhole pulse radar  

SciTech Connect

A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole.

Chang, Hsi-Tien (Albuquerque, NM)

1989-01-01

395

Adaptive MIMO radar waveforms  

Microsoft Academic Search

Multiple-Input, Multiple-Output (MIMO) radars enhance performance by transmitting and receiving coded waveforms from multiple locations. To date, the theoretical literature on MIMO radar has focused largely on the use of ldquoorthogonal waveforms.rdquo Practical approaches to approximate orthogonality (e.g., via waveforms characterized by low cross-correlation and low autocorrelation sidelobe levels) have also started to emerge. We show, however, that such waveforms

Daniel J. Rabideau; Lexington MA

2008-01-01

396

Sea Clutter Reduction and Target Enhancement by Neural Networks in a Marine Radar System  

PubMed Central

The presence of sea clutter in marine radar signals is sometimes not desired. So, efficient radar signal processing techniques are needed to reduce it. In this way, nonlinear signal processing techniques based on neural networks (NNs) are used in the proposed clutter reduction system. The developed experiments show promising results characterized by different subjective (visual analysis of the processed radar images) and objective (clutter reduction, target enhancement and signal-to-clutter ratio improvement) criteria. Moreover, a deep study of the NN structure is done, where the low computational cost and the high processing speed of the proposed NN structure are emphasized. PMID:22573993

Vicen-Bueno, Raúl; Carrasco-Álvarez, Rubén; Rosa-Zurera, Manuel; Nieto-Borge, José Carlos

2009-01-01

397

Wide band stepped frequency ground penetrating radar  

DOEpatents

A wide band ground penetrating radar system (10) embodying a method wherein a series of radio frequency signals (60) is produced by a single radio frequency source (16) and provided to a transmit antenna (26) for transmission to a target (54) and reflection therefrom to a receive antenna (28). A phase modulator (18) modulates those portion of the radio frequency signals (62) to be transmitted and the reflected modulated signal (62) is combined in a mixer (34) with the original radio frequency signal (60) to produce a resultant signal (53) which is demodulated to produce a series of direct current voltage signals (66) the envelope of which forms a cosine wave shaped plot (68) which is processed by a Fast Fourier Transform unit 44 into frequency domain data (70) wherein the position of a preponderant frequency is indicative of distance to the target (54) and magnitude is indicative of the signature of the target (54).

Bashforth, Michael B. (Buellton, CA); Gardner, Duane (Santa Maria, CA); Patrick, Douglas (Santa Maria, CA); Lewallen, Tricia A. (Ventura, CA); Nammath, Sharyn R. (Santa Barbara, CA); Painter, Kelly D. (Goleta, CA); Vadnais, Kenneth G. (Alexandria, VA)

1996-01-01

398

Wide band stepped frequency ground penetrating radar  

DOEpatents

A wide band ground penetrating radar system is described embodying a method wherein a series of radio frequency signals is produced by a single radio frequency source and provided to a transmit antenna for transmission to a target and reflection therefrom to a receive antenna. A phase modulator modulates those portions of the radio frequency signals to be transmitted and the reflected modulated signal is combined in a mixer with the original radio frequency signal to produce a resultant signal which is demodulated to produce a series of direct current voltage signals, the envelope of which forms a cosine wave shaped plot which is processed by a Fast Fourier Transform Unit 44 into frequency domain data wherein the position of a preponderant frequency is indicative of distance to the target and magnitude is indicative of the signature of the target. 6 figs.

Bashforth, M.B.; Gardner, D.; Patrick, D.; Lewallen, T.A.; Nammath, S.R.; Painter, K.D.; Vadnais, K.G.

1996-03-12

399

On wave radar measurement  

NASA Astrophysics Data System (ADS)

The SAAB REX WaveRadar sensor is widely used for platform-based wave measurement systems by the offshore oil and gas industry. It offers in situ surface elevation wave measurements at relatively low operational costs. Furthermore, there is adequate flexibility in sampling rates, allowing in principle sampling frequencies from 1 to 10 Hz, but with an angular microwave beam width of 10° and an implied ocean surface footprint in the order of metres, significant limitations on the spatial and temporal resolution might be expected. Indeed there are reports that the accuracy of the measurements from wave radars may not be as good as expected. We review the functionality of a WaveRadar using numerical simulations to better understand how WaveRadar estimates compare with known surface elevations. In addition, we review recent field measurements made with a WaveRadar set at the maximum sampling frequency, in the light of the expected functionality and the numerical simulations, and we include inter-comparisons between SAAB radars and buoy measurements for locations in the North Sea.

Ewans, Kevin; Feld, Graham; Jonathan, Philip

2014-08-01

400

On wave radar measurement  

NASA Astrophysics Data System (ADS)

The SAAB REX WaveRadar sensor is widely used for platform-based wave measurement systems by the offshore oil and gas industry. It offers in situ surface elevation wave measurements at relatively low operational costs. Furthermore, there is adequate flexibility in sampling rates, allowing in principle sampling frequencies from 1 to 10 Hz, but with an angular microwave beam width of 10° and an implied ocean surface footprint in the order of metres, significant limitations on the spatial and temporal resolution might be expected. Indeed there are reports that the accuracy of the measurements from wave radars may not be as good as expected. We review the functionality of a WaveRadar using numerical simulations to better understand how WaveRadar estimates compare with known surface elevations. In addition, we review recent field measurements made with a WaveRadar set at the maximum sampling frequency, in the light of the expected functionality and the numerical simulations, and we include inter-comparisons between SAAB radars and buoy measurements for locations in the North Sea.

Ewans, Kevin; Feld, Graham; Jonathan, Philip

2014-09-01

401

Target Detection and Localization Using MIMO Radars and Sonars  

Microsoft Academic Search

In this paper, we propose a new space-time coding configuration for target detection and localization by radar or sonar systems. In common active array systems, the transmitted signal is usually coherent between the different elements of the array. This configuration does not allow array processing in the transmit mode. However, space-time coding of the transmitted signals allows to digitally steer

Ilya Bekkerman; Joseph Tabrikian

2006-01-01

402

MIMO radar: an idea whose time has come  

Microsoft Academic Search

It has recently been shown that multiple-input multiple-output (MIMO) antenna systems have the potential to improve dramatically the performance of communication systems over single antenna systems. Unlike beamforming, which presumes a high correlation between signals either transmitted or received by an array, the MIMO concept exploits the independence between signals at the array elements. In conventional radar, target scintillations are

Eran Fishlert; Alex Haimovicht; Rick Blumt; Dmitry Chizhik; Len Cimini; Reinaldo Valenzuela

2004-01-01

403

33 CFR 164.38 - Automatic radar plotting aids (ARPA).  

Code of Federal Regulations, 2013 CFR

...the effects of low signal to noise and low signal to clutter ratios...separate or integral part of the ship's radar. However, the...experienced on the bridge of a ship by day and by night. Screening...all tracked targets of an own ship manoeuvre without...

2013-07-01

404

33 CFR 164.38 - Automatic radar plotting aids (ARPA).  

Code of Federal Regulations, 2010 CFR

...the effects of low signal to noise and low signal to clutter ratios...separate or integral part of the ship's radar. However, the...experienced on the bridge of a ship by day and by night. Screening...all tracked targets of an own ship manoeuvre without...

2010-07-01

405

33 CFR 164.38 - Automatic radar plotting aids (ARPA).  

Code of Federal Regulations, 2011 CFR

...the effects of low signal to noise and low signal to clutter ratios...separate or integral part of the ship's radar. However, the...experienced on the bridge of a ship by day and by night. Screening...all tracked targets of an own ship manoeuvre without...

2011-07-01

406

33 CFR 164.38 - Automatic radar plotting aids (ARPA).  

Code of Federal Regulations, 2012 CFR

...the effects of low signal to noise and low signal to clutter ratios...separate or integral part of the ship's radar. However, the...experienced on the bridge of a ship by day and by night. Screening...all tracked targets of an own ship manoeuvre without...

2012-07-01

407

Some comments on emittance of H/sup -/ ion beams  

SciTech Connect

Some properties of emittance, emittance distributions, and measurement techniques are reviewed. In comparing the results of measurements with several different types of H/sup -/ sources with each other and with emittance formulae, it is concluded that the emittance of surface-type sources is dominated by the effective ion temperature. Other effects, such as ion-optical distortions, may account for the emittance of volume-type sources.

Allison, P.

1986-01-01

408

Wall characterization for through-the-wall radar applications  

NASA Astrophysics Data System (ADS)

There has been continuing interest in the penetration of multilayer building materials, such as wood walls with air gaps and concrete hollow core block, using through-the-wall (TTW) radar systems. TTW operational techniques and signal propagation paths vary depending on how the TTW system is intended to be operated. For example, the operator of a TTW radar may be required to place the radar against the intervening wall of interest while collecting data. Other operational doctrines allow the radar to be operated in a stand-off mode from the wall. The stand-off distances can vary from feet to hundreds of feet, depending on the type of radar being used. When a signal is propagated through a multilayer wall with air gaps between the material and the wall construction uses materials of radically different dielectric constants, attenuation may not be the only effect that the probing signal experiences passing through the wall. This paper presents measurements of a hollow core concrete block wall and the measurement of a standard wall constructed of siding and wallboard. Both types of walls are typically found in most U.S. homes. These limited measurements demonstrate that the type of wall being penetrated by a wideband signal can modify the probing signal.

Greneker, Gene; Rausch, E. O.

2008-04-01

409

Informational analysis for compressive sampling in radar imaging.  

PubMed

Compressive sampling or compressed sensing (CS) works on the assumption of the sparsity or compressibility of the underlying signal, relies on the trans-informational capability of the measurement matrix employed and the resultant measurements, operates with optimization-based algorithms for signal reconstruction and is thus able to complete data compression, while acquiring data, leading to sub-Nyquist sampling strategies that promote efficiency in data acquisition, while ensuring certain accuracy criteria. Information theory provides a framework complementary to classic CS theory for analyzing information mechanisms and for determining the necessary number of measurements in a CS environment, such as CS-radar, a radar sensor conceptualized or designed with CS principles and techniques. Despite increasing awareness of information-theoretic perspectives on CS-radar, reported research has been rare. This paper seeks to bridge the gap in the interdisciplinary area of CS, radar and information theory by analyzing information flows in CS-radar from sparse scenes to measurements and determining sub-Nyquist sampling rates necessary for scene reconstruction within certain distortion thresholds, given differing scene sparsity and average per-sample signal-to-noise ratios (SNRs). Simulated studies were performed to complement and validate the information-theoretic analysis. The combined strategy proposed in this paper is valuable for information-theoretic orientated CS-radar system analysis and performance evaluation. PMID:25811226

Zhang, Jingxiong; Yang, Ke

2015-01-01

410

High resolution lunar radar studies: Preliminary results  

NASA Technical Reports Server (NTRS)

High resolution radar data for the lunar surface were acquired over 14 sites in June and November 1990 using the new 10 MHz data taking system at the Arecibo Observatory. The raw data collected for each site covers an area approximately 100 by 400 km and will be processed using delay-Doppler techniques into images of backscatter cross section with three fo four independent looks. All observations transmitted a circularly polarized signal and both senses of circular polarization were received containing the polarized and depolarized component of the backscatter signal. The relative power in these two polarizations provides useful information on properties of the surface, in particular surface roughness. The effort to date focused on the initial data analysis with new software written to perform a full synthetic aperture focusing on the raw radar data. This analysis will involve the use of complementary high resolution optical and topographic data sets to aid interpretation of surface scattering mechanisms.

Stacy, Nicholas J. S.; Campbell, Donald B.

1991-01-01

411

Prospects for a Solar Radar at Arecibo  

NASA Astrophysics Data System (ADS)

The idea of probing the solar corona with radar is so obvious that the Sun was the second target (after the moon) attempted in the development of radar astronomy. Echoes were detected by the Stanford group in 1960, and extensive observations were made between 1961 and 1969 by the MIT group. The results were unexpected in every respect: the echo power was weaker than expected and highly variable; the Doppler shift and broadening were greater than expected and were also highly variable; and the delay was more variable than expected. The results were never explained, even qualitatively. It became impossible to repeat them because radar astronomy evolved towards use of higher frequencies which penetrate the corona and are absorbed in the photosphere. In retrospect the early work was "ahead of its time" as solar echoes will be strongly affected by coronal holes and coronal mass ejections, neither of which were known in 1969. The purpose of this paper is to point out an opportunity to create a solar radar at the Arecibo Observatory, in conjunction with a proposed ionospheric heater. The two applications will not interfere and cost-sharing makes both feasible. The new radar will have five major improvements over the original: (1) complementary solar observations; (2) modern signal processing; (3) dual polarization; (4) frequency agility; (5) tracking. These will provide many benefits, but the "killer-app" may be the ability to directly measure the coronal magnetic field. The frequency will be tunable between 18 MHz and 26 MHz, which correspond to reflection heights of 1.85 Rs and 1.65 Rs respectively. Here we will summarize the early results; outline the design of the proposed radar; and present some simulations of its performance.

Coles, W. A.

2002-05-01

412

Monitoring internal organ motion with continuous wave radar in CT  

SciTech Connect

Purpose: To avoid motion artifacts in medical imaging or to minimize the exposure of healthy tissues in radiation therapy, medical devices are often synchronized with the patient's respiratory motion. Today's respiratory motion monitors require additional effort to prepare the patients, e.g., mounting a motion belt or placing an optical reflector on the patient's breast. Furthermore, they are not able to measure internal organ motion without implanting markers. An interesting alternative to assess the patient's organ motion is continuous wave radar. The aim of this work is to design, implement, and evaluate such a radar system focusing on application in CT.Methods: The authors designed a radar system operating in the 860 MHz band to monitor the patient motion. In the intended application of the radar system, the antennas are located close to the patient's body inside the table of a CT system. One receive and four transmitting antennas are used to avoid the requirement of exact patient positioning. The radar waves propagate into the patient's body and are reflected at tissue boundaries, for example at the borderline between muscle and adipose tissue, or at the boundaries of organs. At present, the authors focus on the detection of respiratory motion. The radar system consists of the hardware mentioned above as well as of dedicated signal processing software to extract the desired information from the radar signal. The system was evaluated using simulations and measurements. To simulate the radar system, a simulation model based on radar and wave field equations was designed and 4D respiratory-gated CT data sets were used as input. The simulated radar signals and the measured data were processed in the same way. The radar system hardware and the signal processing algorithms were tested with data from ten volunteers. As a reference, the respiratory motion signal was recorded using a breast belt simultaneously with the radar measurements.Results: Concerning the measurements of the test persons, there is a very good correlation (?= 0.917) between the respiratory motion phases received by the radar system and the external motion monitor. Our concept of using an array of transmitting antennas turned out to be widely insensitive to the positioning of the test persons. A time shift between the respiratory motion curves recorded with the radar system and the motion curves from the external respiratory monitor was observed which indicates a slight difference between internal organ motion and motion detected by the external respiratory monitor. The simulations were in good accordance with the measurements.Conclusions: A continuous wave radar operating in the near field of the antennas can be used to determine the respiratory motion of humans accurately. In contrast to trigger systems used today, the radar system is able to measure motion inside the body. If such a monitor was routinely available in clinical CT, it would be possible optimizing the scan start with respect to the respiratory state of the patient. Breathing commands would potentially widely be avoided, and as far as uncooperative patients or children are concerned, less sedation might be necessary. Further applications of the radar system could be in radiation therapy or interventional imaging for instance.

Pfanner, Florian [Institute of Medical Physics, University of Erlangen–Nürnberg, 91052 Erlangen, Germany and Siemens AG, Healthcare Sector, Siemensstr. 1, 91301 Forchheim (Germany)] [Institute of Medical Physics, University of Erlangen–Nürnberg, 91052 Erlangen, Germany and Siemens AG, Healthcare Sector, Siemensstr. 1, 91301 Forchheim (Germany); Maier, Joscha [Medical Physics in Radiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany)] [Medical Physics in Radiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Allmendinger, Thomas; Flohr, Thomas [Siemens AG, Healthcare Sector, Siemensstr. 1, 91301 Forchheim (Germany)] [Siemens AG, Healthcare Sector, Siemensstr. 1, 91301 Forchheim (Germany); Kachelrieß, Marc [Institute of Medical Physics, University of Erlangen–Nürnberg, 91052 Erlangen, Germany and Medical Physics in Radiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany)] [Institute of Medical Physics, University of Erlangen–Nürnberg, 91052 Erlangen, Germany and Medical Physics in Radiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany)

2013-09-15

413

Optical imaging of alpha emitters: simulations, phantom, and in vivo results.  

PubMed

There has been growing interest in investigating both the in vitro and in vivo detection of optical photons from a plethora of beta emitters using optical techniques. In this paper we have investigated an alpha particle induced fluorescence signal by using a commercial CCD-based small animal optical imaging system. The light emission of a (241)Am source was simulated using GEANT4 and tested in different experimental conditions including the imaging of in vivo tissue. We believe that the results presented in this work can be useful to describe a possible mechanism for the in vivo detection of alpha emitters used for therapeutic purposes. PMID:22191928

Boschi, Federico; Meo, Sergio Lo; Rossi, Pier Luca; Calandrino, Riccardo; Sbarbati, Andrea; Spinelli, Antonello E

2011-12-01

414

Pulse Doppler radar simulation study  

NASA Astrophysics Data System (ADS)

In the past several years two different models have been produced for predicting detection performance of space-based and airborne coherent pulsed radars. The present work describes enhancements incorporated in the software including: (1) conversion of the code to ANSI standard FORTRAN-77; (2) development and implementation of a suitable algorithm for the evaluation of the clutter covariance matrix of an array processor; (3) derivation and coding of the linear frequency modulated (LFM) waveform simulation capability for radar system performance evaluation; and (4) implementation of a Monte Carlo code to study receiver imperfections for the non-frequency modulated (NFM) waveform as well as the derivation of analytical expressions describing the effects of linear receiver imperfections on this waveform. Single precision accuracy was found to be close to that of double precision. The looping of the clutter patches was found to be the time limiting process in the clutter calculations and hence little run time was gained by use of single precision. Evaluation of the LFM waveform showed range velocity coupling and a nonstationary behaviour or the return signal. Detection performance of the LFM waveform is consistently better than that of the NFM waveform.

Gibb, Murray; Lightstone, Leonard; Saper, Ronald H.

1988-10-01

415

Progress in coherent laser radar  

NASA Astrophysics Data System (ADS)

Considerable progress with coherent laser radar has been made over the last few years, most notably perhaps in the available range of high performance devices and components and the confidence with which systems may now be taken into the field for prolonged periods of operation. Some of this increasing maturity was evident at the 3rd Topical Meeting on Coherent Laser Radar: Technology and Applications. Topics included in discussions were: mesoscale wind fields, nocturnal valley drainage and clear air down bursts; airborne Doppler lidar studies and comparison of ground and airborne wind measurement; wind measurement over the sea for comparison with satellite borne microwave sensors; transport of wake vortices at airfield; coherent DIAL methods; a newly assembled Nd-YAG coherent lidar system; backscatter profiles in the atmosphere and wavelength dependence over the 9 to 11 micrometer region; beam propagation; rock and soil classification with an airborne 4-laser system; technology of a global wind profiling system; target calibration; ranging and imaging with coherent pulsed and CW system; signal fluctuations and speckle. Some of these activities are briefly reviewed.

Vaughan, J. M.

1986-08-01

416

An image-based approach for classification of human micro-doppler radar signatures  

NASA Astrophysics Data System (ADS)

With the advances in radar technology, there is an increasing interest in automatic radar-based human gait identification. This is because radar signals can penetrate through most dielectric materials. In this paper, an image-based approach is proposed for classifying human micro-Doppler radar signatures. The time-varying radar signal is first converted into a time-frequency representation, which is then cast as a two-dimensional image. A descriptor is developed to extract micro-Doppler features from local time-frequency patches centered along the torso Doppler frequency. Experimental results based on real data collected from a 24-GHz Doppler radar showed that the proposed approach achieves promising classification performance.

Tivive, Fok Hing Chi; Phung, Son Lam; Bouzerdoum, Abdesselam

2013-05-01

417

AirRadar 1.1.1  

NSDL National Science Digital Library

If you are out and about and looking for a wireless network for your computer, you may want to take advantage of the AirRadar application. The application will list all open and closed networks in range, type of encryption, and channel. Advanced users will also appreciate the fact that the application can also track noise and signal strengths in a graph format. This version is compatible with computers running Mac OS X 10.4 and 10.5.

418

Radar MeteorologyRadar Meteorology Feb 20, 1941 10 cm (S-band) radar used to track rain showers (Ligda)  

E-print Network

Radar MeteorologyRadar Meteorology Feb 20, 1941 10 cm (S-band) radar used to track rain showers similar observations in the early 1940's (U.S. Air Corps meteorologists receiving "radar" training at MIT in 1943 First operational weather radar, Panama, 1943 Science of radar meteorology born from WWII research

Rutledge, Steven

419

Modified theoretical minimum emittance lattice for an electron storage ring with extreme-low emittance  

Microsoft Academic Search

In the continuing efforts to reduce the beam emittance of an electron storage ring composed of theoretical minimum emittance (TME) lattice, down to a level of several tens of picometers, nonlinear dynamics grows to be a great challenge to the performance of the storage ring because of the strong sextupoles needed to compensate for its large global natural chomaticities coupled

Yi Jiao; Yunhai Cai; Alexander Wu Chao

2011-01-01

420

66. VIEW SHOWING HOLD FOR RADAR CABLES AT RADAR SITE, ...  

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

66. VIEW SHOWING HOLD FOR RADAR CABLES AT RADAR SITE, LOOKING NORTH Everett Weinreb, photographer, March 1988 - Mount Gleason Nike Missile Site, Angeles National Forest, South of Soledad Canyon, Sylmar, Los Angeles County, CA

421

Radar Range Sidelobe Reduction Using Adaptive Pulse Compression Technique  

NASA Technical Reports Server (NTRS)

Pulse compression has been widely used in radars so that low-power, long RF pulses can be transmitted, rather than a highpower short pulse. Pulse compression radars offer a number of advantages over high-power short pulsed radars, such as no need of high-power RF circuitry, no need of high-voltage electronics, compact size and light weight, better range resolution, and better reliability. However, range sidelobe associated with pulse compression has prevented the use of this technique on spaceborne radars since surface returns detected by range sidelobes may mask the returns from a nearby weak cloud or precipitation particles. Research on adaptive pulse compression was carried out utilizing a field-programmable gate array (FPGA) waveform generation board and a radar transceiver simulator. The results have shown significant improvements in pulse compression sidelobe performance. Microwave and millimeter-wave radars present many technological challenges for Earth and planetary science applications. The traditional tube-based radars use high-voltage power supply/modulators and high-power RF transmitters; therefore, these radars usually have large size, heavy weight, and reliability issues for space and airborne platforms. Pulse compression technology has provided a path toward meeting many of these radar challenges. Recent advances in digital waveform generation, digital receivers, and solid-state power amplifiers have opened a new era for applying pulse compression to the development of compact and high-performance airborne and spaceborne remote sensing radars. The primary objective of this innovative effort is to develop and test a new pulse compression technique to achieve ultrarange sidelobes so that this technique can be applied to spaceborne, airborne, and ground-based remote sensing radars to meet future science requirements. By using digital waveform generation, digital receiver, and solid-state power amplifier technologies, this improved pulse compression technique could bring significant impact on future radar development. The novel feature of this innovation is the non-linear FM (NLFM) waveform design. The traditional linear FM has the limit (-20 log BT -3 dB) for achieving ultra-low-range sidelobe in pulse compression. For this study, a different combination of 20- or 40-microsecond chirp pulse width and 2- or 4-MHz chirp bandwidth was used. These are typical operational parameters for airborne or spaceborne weather radars. The NLFM waveform design was then implemented on a FPGA board to generate a real chirp signal, which was then sent to the radar transceiver simulator. The final results have shown significant improvement on sidelobe performance compared to that obtained using a traditional linear FM chirp.

Li, Lihua; Coon, Michael; McLinden, Matthew

2013-01-01

422

Direction of Arrival Estimation of Wide-Band Emitters  

NASA Astrophysics Data System (ADS)

Most published algorithms for DOA (Direction of Arrival) estimation of incoming signals by spatially dispersed electromagnetic or acoustic sources rely on the narrow -band approximation. This approach is inadequate from at least two standpoints. First, the approximation breaks down in many practical situation of interest; and, second, it inhibits the exploitation of intrinsic degrees of freedom of wide-band emitters to achieve additional improvements in angular resolution. In this dissertation the direction of arrival estimation problem is examined without employing the customary narrow-band restriction. A class of algorithms that has been successfully employed for DOA estimation of narrow-band signals exploits the eigenstructure of the array correlation matrix. Although they are sub-optimum, these algorithms enjoy substantial computational advantages over the optimum maximum likelihood approaches. It is shown that the frequency domain representation of the array output leads to a spectral coherence matrix that exhibits an eigenstructure similar to the correlation matrix used under the narrow-band approximation. As a consequence, narrow-band eigenbased algorithms can be adopted to DOA estimation without restrictions on signal bandwidth. The Spectral Coherence Technique (SCT) is applied in conjunction with the MUSIC, the Root-Music and a modified form of the Pisarenko algorithms to DOA estimation of wide -band emitters using linear arrays. Simulation indicate that all three algorithms afford comparable performance: the variance of the angle of arrival estimate decreases approximately inversely with the signal time bandwidth product. They differ, however, with regard to computational efficiency. In particular, the wide-band version of the algorithm MUSIC requires substantially more processing time than either the Pisarenko or the Root-Music algorithms. These algorithms also yield comparable performance to an alternative approach using frequency segmentation (WiDE), which has a computational efficiency comparable to MUSIC.

Hojati, Shahram

423

On the phase biases of multiple-frequency radar returns of mesosphere-stratosphere-troposphere radar  

NASA Astrophysics Data System (ADS)

The frequency domain interferometry (FDI) technique uses two or more frequencies to measure the positions and thicknesses of the atmospheric thin layers embedded in the radar volume, in which the cross-correlation analyses of the radar echoes for the pairs of carrier frequencies are performed and the resultant amplitudes and phases (FDI phase) are both employed. However, in light of the possibility that the characteristics of radar system, mean refractivity gradient, and other factors that would significantly affect the FDI phase, calibration of the FDI phase is required to improve the measurement. In this study we employed three methods in measuring the phase bias in the FDI observation using the Chung-Li VHF radar; namely, (1) histogram of the FDI phases, (2) relationship between echo power and FDI phase, and (3) the FDI phase of aircraft. Both methods 1 and 2 are based on the range weighting effect on the radar echoes returned from the atmospheric scatterers; however, the first produced smaller FDI phase bias than the second. To examine such discrepancy in the results of methods 1 and 2, method 3 was exploited and provided more consistent values of phase biases with those of method 2. Considering that the radar echoes reflected from aircrafts are not related to uncertain conditions of the atmosphere such as mean reflectivity gradients and statistical characteristics, the results of methods 2 and 3 may be more reliable. Besides, the first two methods demonstrated that the FDI phase bias was quasi-linearly dependent on the separation of frequency pair, which not only consolidates the existence of the FDI phase bias but also indicates that a systematic phase compensation for the FDI analysis is possible. For example, considering 0.1-, 0.4-, and 0.8-?s time delays of signals for the returns of 1-, 2-, and 4-?s pulse lengths, respectively, the FDI phase biases can be removed effectively. Same methods and procedures can be applied to other radar systems.

Chen, Jenn-Shyong

2004-10-01

424

Airborne Radar Observations of Severe Hailstorms: Implications for Future Spaceborne Radar  

NASA Technical Reports Server (NTRS)

A new dual-frequency (Ku and Ka band) nadir-pointing Doppler radar on the high-altitude NASA ER-2 aircraft, called the High-Altitude Imaging Wind and Rain Airborne Profiler (HIWRAP), has collected data over severe thunderstorms in Oklahoma and Kansas during the Midlatitude Continental Convective Clouds Experiment (MC3E). The overarching motivation for this study is to understand the behavior of the dualwavelength airborne radar measurements in a global variety of thunderstorms and how these may relate to future spaceborne-radar measurements. HIWRAP is operated at frequencies that are similar to those of the precipitation radar on the Tropical Rainfall Measuring Mission (Ku band) and the upcoming Global Precipitation Measurement mission satellite's dual-frequency (Ku and Ka bands) precipitation radar. The aircraft measurements of strong hailstorms have been combined with ground-based polarimetric measurements to obtain a better understanding of the response of the Ku- and Ka-band radar to the vertical distribution of the hydrometeors, including hail. Data from two flight lines on 24 May 2011 are presented. Doppler velocities were approx. 39m/s2at 10.7-km altitude from the first flight line early on 24 May, and the lower value of approx. 25m/s on a second flight line later in the day. Vertical motions estimated using a fall speed estimate for large graupel and hail suggested that the first storm had an updraft that possibly exceeded 60m/s for the more intense part of the storm. This large updraft speed along with reports of 5-cm hail at the surface, reflectivities reaching 70 dBZ at S band in the storm cores, and hail signals from polarimetric data provide a highly challenging situation for spaceborne-radar measurements in intense convective systems. The Ku- and Ka-band reflectivities rarely exceed approx. 47 and approx. 37 dBZ, respectively, in these storms.

Heymsfield, Gerald M.; Tian, Lin; Li, Lihua; McLinden, Matthew; Cervantes, Jaime I.

2013-01-01

425

Near-Real Time Quality Control of surface current maps from High-Frequency (HF) radars  

NASA Astrophysics Data System (ADS)

A method for real-time quality control and despiking of sea surface current maps from High-Frequency (HF) SeaSonde radars based on the Signal-to-Noise ratios of the Doppler velocities from individual radar stations is proposed and discussed. Benefits of using a conservative weighted least-squares versus a more traditional least-squares approach for the total vector derivation are demonstrated on a network of radars operating in the Northern Adriatic Sea

Cosoli, S.; Bolzon, G.

2009-04-01

426

A FMCW Radar Acquisition and Process System Based on LabVIEW  

Microsoft Academic Search

This paper presents a acquisition and process system for frequency modulation continuous wave (FMCW) radar. The procedure is designed by LabVIEW7.0. The system adopts FMCW radar sensor and high-quality data acquisition card. The intermediate frequency (IF) signal of the FMCW radar can be collected in time. The intermediate frequency, distance and velocity forward vehicle can be calculated by an improved

Zhang Da-Biao; Zhao Zeng-rong; Bai Ran

2009-01-01

427

Weather Radar and Instrumentation: Laboratory Modules  

NSDL National Science Digital Library

These 16 radar education modules, developed for the Weather Radar and Instrumentation Curriculum at the University of Oklahoma, provide hands-on instruction for beginning, intermediate, or advanced students to learn about radar systems, especially weather radar. Topics include hardware, weather radar, adaptive systems, advanced hydrometeors, applications of weather radar, and atmospheric interpretations. The modules may be downloaded.

428

A frequency averaging method to improve sea-state measurements with an HF skywave radar  

Microsoft Academic Search

A frequency averaging method which can improve the quality of averaged spectra of HF signals scattered by the sea is described. The method is compared to the classical single-frequency pulse-radar. Using the skywave radar of Valensole, France, the statistical independence of signals scattered by the sea at close frequencies is experimentally verified. Spectra of signals reflected by an F2 ionospheric

Jacques Parent

1987-01-01

429

Space Radar Image of Raco Biomass Map  

NASA Technical Reports Server (NTRS)

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

1999-01-01

430

Radar Image, Color as Height , Salalah, Oman  

NASA Technical Reports Server (NTRS)

This radar image includes the city of Salalah, the second largest city in Oman. It illustrates how topography determines local climate and, in turn, where people live. This area on the southern coast of the Arabian Peninsula is characterized by a narrow coastal plain (bottom) facing southward into the Arabian Sea, backed by the steep escarpment of the Qara Mountains. The backslope of the Qara Mountains slopes gently into the vast desert of the Empty Quarter (at top). This area is subject to strong monsoonal storms from the Arabian Sea during the summer, when the mountains are enveloped in a sort of perpetual fog. The moisture from the monsoon enables agriculture on the Salalah plain, and also provides moisture for Frankincense trees growing on the desert (north) side of the mountains. In ancient times, incense derived from the sap of the Frankincense tree was the basis for an extremely lucrative trade. Radar and topographic data are used by historians and archaeologists to discover ancient trade routes and other significant ruins.

This image combines two types of data from the Shuttle Radar Topography Mission. The image brightness corresponds to the strength of the radar signal reflected from the ground, while colors show the elevation as measured by SRTM. Colors range from green at the lowest elevations to brown at the highest elevations. This image contains about 1070 meters (3500 feet) of total relief. White speckles on the face of some of the mountains are holes in the data caused by steep terrain. These will be filled using coverage from an intersecting pass.

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

Size: 56 by 50 kilometers (35 by 32 miles) Location: 17 deg. North lat., 54 deg. East lon. Orientation: North at top Date Acquired: February 15, 2000

2000-01-01

431

Compressive wideband microwave radar holography  

NASA Astrophysics Data System (ADS)

Compressive sensing has emerged as a topic of great interest for radar applications requiring large amounts of data storage. Typically, full sets of data are collected at the Nyquist rate only to be compressed at some later point, where information-bearing data are retained and inconsequential data are discarded. However, under sparse conditions, it is possible to collect data at random sampling intervals less than the Nyquist rate and still gather enough meaningful data for accurate signal reconstruction. In this paper, we employ sparse sampling techniques in the recording of digital microwave holograms over a two-dimensional scanning aperture. Using a simple and fast non-linear interpolation scheme prior to image reconstruction, we show that the reconstituted image quality is well-retained with limited perceptual loss.

Wilson, Scott A.; Narayanan, Ram M.

2014-05-01

432

33. Perimeter acquisition radar building room #320, perimeter acquisition radar ...  

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

33. Perimeter acquisition radar building room #320, perimeter acquisition radar operations center (PAROC), contains the tactical command and control group equipment required to control the par site. Showing spacetrack monitor console - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

433

Novel deep-blue emitting phosphorescent emitter  

NASA Astrophysics Data System (ADS)

Currently, one of the most challenging applications for OLEDs is the full color display. The most energy-efficient way to realize light generation in OLEDs is by using phosphorescent emitters. Green and red emitters have already been demonstrated, but the search for blue emitting organic phosphorescent emitters with good color purity is still ongoing with arduous effort. Here we present our work with a new material developed at BASF which allows phosphorescent emission in the deep-blue spectral range. The emitter has an emission maximum at 400 nm, which gives CIE color coordinates of x = 0.16 and y = 0.06. An OLED device made with this new material shows a maximum external quantum efficiency of 1.5 %. The OLED was built in a three layer structure, with the emitting zone being a hybrid guest-host system. As host material we used the optically and electronically inert polymer poly-methyl-methacrylate (PMMA). Because of its lack of charge transport abilities we doped the host material with a high concentration of the triplet emitting material, i.e. the emitter itself is also used as charge transport material.

Schildknecht, C.; Ginev, G.; Kammoun, A.; Riedl, T.; Kowalsky, W.; Johannes, H.-H.; Lennartz, C.; Kahle, K.; Egen, M.; Geßner, T.; Bold, M.; Nord, S.; Erk, P.

2005-10-01

434

Longitudinal emittance measurements at REX-ISOLDE  

NASA Astrophysics Data System (ADS)

We report on measurements of the longitudinal emittance at the Radioactive ion beam EXperiment (REX) at ISOLDE, CERN. The rms longitudinal emittance was measured as 0.34±0.08 ? ns keV/u at the output of the RFQ and as 0.36±0.04 ? ns keV/ u in front of the third 7-gap split-ring resonator (7G3) using the three-gradient technique; systematic errors are not included but are estimated at approximately 10%. The 86% emittance was measured a factor of approximately 4.4 times larger than the rms emittance at 1.48±0.2 and 1.55±0.12 ? ns keV/ u at the RFQ and 7G3, respectively. The REX switchyard magnet was used as a spectrometer to analyse the energy spread of the beam as it was manipulated by varying the voltage of the rebuncher (ReB) and 7G3 cavities operating at non-accelerating phases. The transfer matrix for a multi-gap bunching cavity is derived and suitably truncated to allow for the accurate reconstruction of the beam parameters from measurement. The technique for measuring the energy spread was rigorously simulated and validated. A silicon detector, in its development phase, was also exploited to measure the longitudinal beam properties. The measured longitudinal emittance is compatible with the acceptance of the HIE-ISOLDE superconducting linac upgrade.

Fraser, M. A.; Zocca, F.; Jones, R. M.; Pasini, M.; Posocco, P. A.; Voulot, D.; Wenander, F.

2012-01-01

435

SRTM Radar - Landsat Image Comparison, Patagonia, Argentina  

NASA Technical Reports Server (NTRS)

In addition to an elevation model of most of Earth'slandmass, the Shuttle Radar Topography Mission will produce C-band radar imagery of the same area. This imagery is essentially a 10-day snapshot view of the Earth, as observed with 5.8 centimeter wavelength radar signals that were transmitted from the Shuttle, reflected by the Earth, and then recorded on the Shuttle. This six-image mosaic shows two examples of SRTM radar images (center) with comparisons to images acquired by the Landsat 7 satellite in the visible wavelengths (left) and an infrared wavelength (right). Both sets of images show lava flows in northern Patagonia, Argentina. In each case, the lava flows are relatively young compared to the surrounding rock formations.

In visible light (left) image brightness corresponds to mineral chemistry and -- as expected -- both lava flows appear dark. Generally, the upper flow sits atop much lighter bedrock, providing good contrast and making the edges of the flow distinct. However, the lower flow borders some rocks that are similarly dark, and the flow boundaries are somewhat obscured. Meanwhile, in the radar images (center), image brightness corresponds to surface roughness (and topographic orientation) and substantial differences between the flows are visible. Much of the top flow appears dark, meaning it is fairly smooth. Consequently, it forms little or no contrast with the smooth and dark surrounding bedrock and thus virtually vanishes from view. However, the lower flow appears rough and bright and mostly forms good contrast with adjacent bedrock such that the flow is locally more distinct here than in the visible Landsat view. For further comparison, infrared Landsat images (right) again show image brightnesses related to mineral chemistry, but the lava flows appear lighter than in the visible wavelengths. Consequently, the lower lava flow becomes fairly obscure among the various surrounding rocks, just as the upper flow did in the radar image. The various differences among all of these images illustrate the importance of illumination wavelength in image interpretation.

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

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

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

2000-01-01

436

Microwave emissions from police radar  

E-print Network

The purpose of this study was to evaluate police officers exposures to microwaves emitted by traffic radar units at the ocular and testicular level. Additionally, comparisons were made of the radar manufacturers published maximum power density...

Fink, John Michael

1994-01-01

437

A fully photonics-based coherent radar system.  

PubMed

The next generation of radar (radio detection and ranging) systems needs to be based on software-defined radio to adapt to variable environments, with higher carrier frequencies for smaller antennas and broadened bandwidth for increased resolution. Today's digital microwave components (synthesizers and analogue-to-digital converters) suffer from limited bandwidth with high noise at increasing frequencies, so that fully digital radar systems can work up to only a few gigahertz, and noisy analogue up- and downconversions are necessary for higher frequencies. In contrast, photonics provide high precision and ultrawide bandwidth, allowing both the flexible generation of extremely stable radio-frequency signals with arbitrary waveforms up to millimetre waves, and the detection of such signals and their precise direct digitization without downconversion. Until now, the photonics-based generation and detection of radio-frequency signals have been studied separately and have not been tested in a radar system. Here we present the development and the field trial results of a fully photonics-based coherent radar demonstrator carried out within the project PHODIR. The proposed architecture exploits a single pulsed laser for generating tunable radar signals and receiving their echoes, avoiding radio-frequency up- and downconversion and guaranteeing both the software-defined approach and high resolution. Its performance exceeds state-of-the-art electronics at carrier frequencies above two gigahertz, and the detection of non-cooperating aeroplanes confirms the effectiveness and expected precision of the system. PMID:24646997

Ghelfi, Paolo; Laghezza, Francesco; Scotti, Filippo; Serafino, Giovanni; Capria, Amerigo; Pinna, Sergio; Onori, Daniel; Porzi, Claudio; Scaffardi, Mirco; Malacarne, Antonio; Vercesi, Valeria; Lazzeri, Emma; Berizzi, Fabrizio; Bogoni, Antonella

2014-03-20

438

A fully photonics-based coherent radar system  

NASA Astrophysics Data System (ADS)

The next generation of radar (radio detection and ranging) systems needs to be based on software-defined radio to adapt to variable environments, with higher carrier frequencies for smaller antennas and broadened bandwidth for increased resolution. Today's digital microwave components (synthesizers and analogue-to-digital converters) suffer from limited bandwidth with high noise at increasing frequencies, so that fully digital radar systems can work up to only a few gigahertz, and noisy analogue up- and downconversions are necessary for higher frequencies. In contrast, photonics provide high precision and ultrawide bandwidth, allowing both the flexible generation of extremely stable radio-frequency signals with arbitrary waveforms up to millimetre waves, and the detection of such signals and their precise direct digitization without downconversion. Until now, the photonics-based generation and detection of radio-frequency signals have been studied separately and have not been tested in a radar system. Here we present the development and the field trial results of a fully photonics-based coherent radar demonstrator carried out within the project PHODIR. The proposed architecture exploits a single pulsed laser for generating tunable radar signals and receiving their echoes, avoiding radio-frequency up- and downconversion and guaranteeing both the software-defined approach and high resolution. Its performance exceeds state-of-the-art electronics at carrier frequencies above two gigahertz, and the detection of non-cooperating aeroplanes confirms the effectiveness and expected precision of the system.

Ghelfi, Paolo; Laghezza, Francesco; Scotti, Filippo; Serafino, Giovanni; Capria, Amerigo; Pinna, Sergio; Onori, Daniel; Porzi, Claudio; Scaffardi, Mirco; Malacarne, Antonio; Vercesi, Valeria; Lazzeri, Emma; Berizzi, Fabrizio; Bogoni, Antonella

2014-03-01

439

Power centroid radar and its rise from the universal cybernetics duality  

NASA Astrophysics Data System (ADS)

Power centroid radar (PC-Radar) is a fast and powerful adaptive radar scheme that naturally surfaced from the recent discovery of the time-dual for information theory which has been named "latency theory." Latency theory itself was born from the universal cybernetics duality (UC-Duality), first identified in the late 1970s, that has also delivered a time dual for thermodynamics that has been named "lingerdynamics" and anchors an emerging lifespan theory for biological systems. In this paper the rise of PC-Radar from the UC-Duality is described. The development of PC-Radar, US patented, started with Defense Advanced Research Projects Agency (DARPA) funded research on knowledge-aided (KA) adaptive radar of the last decade. The outstanding signal to interference plus noise ratio (SINR) performance of PC-Radar under severely taxing environmental disturbances will be established. More specifically, it will be seen that the SINR performance of PC-Radar, either KA or knowledgeunaided (KU), approximates that of an optimum KA radar scheme. The explanation for this remarkable result is that PC-Radar inherently arises from the UC-Duality, which advances a "first principles" duality guidance theory for the derivation of synergistic storage-space/computational-time compression solutions. Real-world synthetic aperture radar (SAR) images will be used as prior-knowledge to illustrate these results.

Feria, Erlan H.

2014-05-01

440

Systems and Methods for Radar Data Communication  

NASA Technical Reports Server (NTRS)

A radar information processing system is operable to process high bandwidth radar information received from a radar system into low bandwidth radar information that may be communicated to a low bandwidth connection coupled to an electronic flight bag (EFB). An exemplary embodiment receives radar information from a radar system, the radar information communicated from the radar system at a first bandwidth; processes the received radar information into processed radar information, the processed radar information configured for communication over a connection operable at a second bandwidth, the second bandwidth lower than the first bandwidth; and communicates the radar information from a radar system, the radar information communicated from the radar system at a first bandwidth.

Bunch, Brian (Inventor); Szeto, Roland (Inventor); Miller, Brad (Inventor)

2013-01-01

441

A 77 GHz SiGe power amplifier for potential applications in automotive radar systems  

Microsoft Academic Search

We present the performance of a 77 GHz power amplifier for potential applications directed towards automotive radar systems. The circuit was fabricated in a SiGe bipolar preproduction technology. A balanced two-stage common emitter circuit topology was used to achieve 6.1 dB of power gain at 77 GHz and 11.6 dBm output power at 1dB compression. The power amplifier uses a

Ullrich R. Pfeiffer; Scott K. Reynolds; Brian A. Floyd

2004-01-01

442

Landmine detection and imaging using Micropower Impulse Radar (MIR)  

SciTech Connect

The Lawrence Livermore National Laboratory (LLNL) has developed radar and imaging technologies with potential applications in mine detection by the armed forces and other agencies involved in determining efforts. These new technologies use a patented ultra-wideband (impulse) radar technology that is compact, low-cost, and low power. Designated as Micropower hnpulse Radar, these compact, self-contained radars can easily be assembled into arrays to form complete ground penetrating radar imaging systems. LLNL has also developed tomographic reconstruction and signal processing software capable of producing high-resolution 2-D and 3-D images of objects buried in materials like soil or concrete from radar data. Preliminary test results have shown that a radar imaging system using these technologies has the ability to image both metallic and plastic land mine surrogate targets buried in 5 to 10 cm of moist soil. In dry soil, the system can detect buried objects to a depth of 30 cm and more. This report describes our initial test results and plans for future work.

Azevedo, S.G.; Gravel, D.T.; Mast, J.E.; Warhus, J.P.

1995-08-07

443

Statistical modeling of interferometric signals in underwater applications  

NASA Astrophysics Data System (ADS)

Current sonar and radar applications use interferometry to estimate the arrival angles of backscattered signals at time-sampling rate. This direction-finding method is based on a phase-difference measurement between two close receivers. To quantify the associated bathymetric measurement quality, it is necessary to model the statistical properties of the interferometric-phase estimator. Thus, this paper investigates the received signal structure, decomposing it into three different terms: a part correlated on the two receivers, an uncorrelated part and an ambient noise term. This paper shows that the uncorrelated part and the noise term can be merged into a unique, random term damaging the measurement performance. Concerning the correlated part, its modulus can be modeled either as a random or a constant variable according to the type of underwater acoustic application. The existence of these two statistical behaviors is verified on real data collected from different underwater scenarios such as a horizontal emitter-receiver communication and a bathymetric seafloor survey. The physical understood of the resulting phase distributions makes it possible to model and simulate the interferometric-signal variance (associated with the measurement accuracy) according to the underwater applications through simple hypotheses.

Llort, Gerard; Sintes, Christophe

2009-05-01

444

Radar data smoothing filter study  

NASA Technical Reports Server (NTRS)

The accuracy of the current Wallops Flight Facility (WFF) data smoothing techniques for a variety of radars and payloads is examined. Alternative data reduction techniques are given and recommendations are made for improving radar data processing at WFF. A data adaptive algorithm, based on Kalman filtering and smoothing techniques, is also developed for estimating payload trajectories above the atmosphere from noisy time varying radar data. This algorithm is tested and verified using radar tracking data from WFF.

White, J. V.

1984-01-01

445

Preliminary results of RMS emittance measurements performed on the sub-picosecond accelerator using beam position monitors  

SciTech Connect

The Sub-picosecond Accelerator at Los Alamos National Laboratory is a 1300 MHz, 8 MeV photoinjector. Concerned mainly with the exploration of bunched electron beams, the Sub-picosecond Accelerator facility is also used for a variety of other research. One ongoing task is the exploitation of the second moment properties of beam position monitor signals to measure the rms emittance. The unique properties of photoinjector beams make Gaussian assumptions about their distribution inaccurate and traditional methods of measuring the rms emittance fail. Using beam position monitors to measure the emittance, however, requires no beam distribution assumptions. Presented here are the first emittance measurements with this method on the Sub-picosecond Accelerator.

Russell, S.J.

1997-08-01

446

Head erosion with emittance growth in PWFA  

SciTech Connect

Head erosion is one of the limiting factors in plasma wakefield acceleration (PWFA). We present a study of head erosion with emittance growth in field-ionized plasma from the PWFA experiments performed at the FACET user facility at SLAC. At FACET, a 20.3 GeV bunch with 1.8 Multiplication-Sign 10{sup 10} electrons is optimized in beam transverse size and combined with a high density lithium plasma for beam-driven plasma wakefield acceleration experiments. A target foil is inserted upstream of the plasma source to increase the bunch emittance through multiple scattering. Its effect on beamplasma interaction is observed with an energy spectrometer after a vertical bend magnet. Results from the first experiments show that increasing the emittance has suppressed vapor field-ionization and plasma wakefields excitation. Plans for the future are presented.

Li, S. Z.; Adli, E.; England, R. J.; Frederico, J.; Gessner, S. J.; Hogan, M. J.; Litos, M. D.; Walz, D. R.; Muggli, P.; An, W.; Clayton, C. E.; Joshi, C.; Lu, W.; Marsh, K. A.; Mori, W.; Vafaei, N. [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States) and SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States) and University of Oslo, Oslo, N-0316 (Norway) and SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Max Planck Institute for Physics, Munich (Germany); University of California, Los Angeles, CA 90095 (United States)

2012-12-21

447

Quantitative deconvolution of human thermal infrared emittance.  

PubMed

The bioheat transfer models conventionally employed in etiology of human thermal infrared (TIR) emittance rely upon two assumptions; universal graybody emissivity and significant transmission of heat from subsurface tissue layers. In this work, a series of clinical and laboratory experiments were designed and carried out to conclusively evaluate the validity of the two assumptions. Results obtained from the objective analyses of TIR images of human facial and tibial regions demonstrated significant variations in spectral thermophysical properties at different anatomic locations on human body. The limited validity of the two assumptions signifies need for quantitative deconvolution of human TIR emittance in clinical, psychophysiological and critical applications. A novel approach to joint inversion of the bioheat transfer model is also introduced, levering the deterministic temperature-dependency of proton resonance frequency in low-lipid human soft tissue for characterizing the relationship between subsurface 3D tissue temperature profiles and corresponding TIR emittance. PMID:23086533

Arthur, D T J; Khan, M M

2013-01-01

448

Observation of Emittance Growth at KEK PS  

NASA Astrophysics Data System (ADS)

Emittance growth has been observed in the transverse direction at the injection period of the 12 GeV main ring of the KEK proton synchrotron. Measurement of the beam profiles using flying wires has revealed a characteristic temporal change of the beam profile within a few milliseconds after injection. Horizontal emittance growth was observed when the horizontal tune was close to the integer. The effect was more enhanced for higher beam intensity and could not be explained with the injection mismatch. Resonance created by the space charge field was the cause of the emittance growth. A multiparticle tracking simulation program, ACCSIM, taking account of space charge effects has qualitatively reproduced the beam profiles.

Igarashi, S.; Miura, T.; Nakamura, E.; Shimosaki, Y.; Shirakata, M.; Takayama, K.; Toyama, T.

2003-12-01

449

The Shuttle Radar Topography Mission  

Microsoft Academic Search

The Shuttle Radar Topography Mission produced the most complete, highest-resolution digital elevation model of the Earth. The project was a joint endeavor of NASA, the National Geospatial-Intelligence Agency, and the German and Italian Space Agencies and flew in February 2000. It used dual radar antennas to acquire interferometric radar data, processed to digital topographic data at 1 arc sec resolution.

Tom G. Farr; Paul A. Rosen; Edward Caro; Robert Crippen; Riley Duren; Scott Hensley; Michael Kobrick; Mimi Paller; Ernesto Rodriguez; Ladislav Roth; David Seal; Scott Shaffer; Joanne Shimada; Jeffrey Umland; Marian Werner; Michael Oskin; Douglas Burbank; Douglas Alsdorf

2007-01-01

450

Optimized aperiodic highly directional narrowband infrared emitters  

NASA Astrophysics Data System (ADS)

Bulk thermal emittance sources possess incoherent, isotropic, and broadband radiation spectra that vary from material to material. However, these radiation spectra can be drastically altered by modifying the geometry of the structures. In particular, several approaches have been proposed to achieve narrowband, highly directional thermal emittance based on photonic crystals, gratings, textured metal surfaces, metamaterials, and shock waves propagating through a crystal. Here we present optimized aperiodic structures for use as narrowband, highly directional thermal infrared emitters for both TE and TM polarizations. One-dimensional layered structures without texturing are preferable to more complex two- and three-dimensional structures because of the relative ease and low cost of fabrication. These aperiodic multilayer structures designed with alternating layers of silicon and silica on top of a semi-infinite tungsten substrate exhibit extremely high emittance peaked around the wavelength at which the structures are optimized. Structures were designed by a genetic optimization algorithm coupled to a transfer matrix code which computed thermal emittance. First, we investigate the properties of the genetic-algorithm optimized aperiodic structures and compare them to a previously proposed resonant cavity design. Second, we investigate a structure optimized to operate at the Wien wavelength corresponding to a near-maximum operating temperature for the materials used in the aperiodic structure. Finally, we present a structure that exhibits nearly monochromatic and highly directional emittance for both TE and TM polarizations at the frequency of one of the molecular resonances of carbon monoxide (CO); hence, the design is suitable for a detector of CO via absorption spectroscopy.

Granier, Christopher H.; Afzal, Francis O.; Min, Changjun; Dowling, Jonathan P.; Veronis, Georgios

2014-09-01

451

Adaptive antenna space-time processing techniques to suppress platform scattered clutter for airborne radar  

NASA Astrophysics Data System (ADS)

Advanced airborne radar may require adaptive space-time processing (STP) to detect small targets at long ranges. STP is a multidimensional adaptive filter that resolves received radar data into a spectrum of plane waves in angular and Doppler Frequency coordinates. The platform of an airborne radar can scatter incident signals into the antenna, spreading the spectra of the clutter signals so that it overlaps the target signal and therefore increases the false alarm rate. To reduce the processing requirements of a full STP filter, a suboptimal architecture with fewer degrees of freedom is demonstrated and compared with the optimal architecture.

Barile, Edward C.; Guella, Thomas P.; Lamensdorf, David

1995-01-01

452

Spaceborne Imaging Radar Symposium  

NASA Technical Reports Server (NTRS)

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

Elachi, C.

1983-01-01

453

Radar Investigations of Asteroids  

NASA Technical Reports Server (NTRS)

Radar investigations of asteroids, including observations during 1984 to 1985 of at least 8 potential targets and continued analyses of radar data obtained during 1980 to 1984 for 30 other asteroids is proposed. The primary scientific objectives include estimation of echo strength, polarization, spectral shape, spectral bandwidth, and Doppler shift. These measurements yield estimates of target size, shape, and spin vector; place constraints on topography, morphology, density, and composition of the planetary surface; yield refined estimates of target orbital parameters; and reveals the presence of asteroidal satellites.

Ostro, S. J.

1984-01-01

454

Radar detection of phobos.  

PubMed

Radar echoes from the martian satellite Phobos provide information about that object's surface properties at scales near the 3.5-cm observing wavelength. Phobos appears less rough than the moon at centimeter-to-decimeter scales. The uppermost few decimeters of the satellite's regolith have a mean bulk density within 20% of 2.0 g cm(-3). The radar signature of Phobos (albedo, polarization ratio, and echo spectral shape) differs from signatures measured for small, Earth-approaching objects, but resembles those of large (>/=100-km), C-class, mainbelt asteroids. PMID:17847261

Ostro, S J; Jurgens, R F; Yeomans, D K; Standish, E M; Greiner, W

1989-03-24

455

Microwave radar oceanographic investigations  

NASA Technical Reports Server (NTRS)

The Radar Ocean Wave Spectrometer (ROWS) technique was developed and demonstrated for measuring ocean wave directional spectra from air and space platforms. The measurement technique was well demonstrated with data collected in a number of flight experiments involving wave spectral comparisons with wave buoys and the Surface Contour Radar (SCR). Recent missions include the SIR-B underflight experiment (1984), FASINEX (1986), and LEWEX (1987). ROWS related activity is presently concentrating on using the aircraft instrument for wave-processes investigations and obtaining the necessary support (consensus) for a satellite instrument development program. Prospective platforms include EOS and the Canadian RADARSAT.

Jackson, F. C.

1988-01-01

456

System-on-Chip based Doppler radar occupancy sensor  

Microsoft Academic Search

System-on-Chip (SoC) based Doppler radar occupancy sensor is developed through non contact detection of respiratory signals. The radio was developed using off the shelf low power RF CC2530 SoC chip by Texas Instruments. In order to save power, the transmitter sends signal intermittently at 2.405 GHz. Reflected pulses are demodulated, and the baseband signals are processed to recover periodic motion.

Ehsan Yavari; Chenyan Song; Victor Lubecke; Olga Boric-Lubecke

2011-01-01

457

Heterojunction solar cell with passivated emitter surface  

DOEpatents

A high-efficiency heterojunction solar cell wherein a thin emitter layer (preferably Ga.sub.0.52 In.sub.0.48 P) forms a heterojunction with a GaAs absorber layer. A passivating window layer of defined composition is disposed over the emitter layer. The conversion efficiency of the solar cell is at least 25.7%. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the window layer.

Olson, Jerry M. (Lakewood, CO); Kurtz, Sarah R. (Golden, CO)

1994-01-01

458

Heterojunction solar cell with passivated emitter surface  

DOEpatents

A high-efficiency heterojunction solar cell is described wherein a thin emitter layer (preferably Ga[sub 0.52]In[sub 0.48]P) forms a heterojunction with a GaAs absorber layer. A passivating window layer of defined composition is disposed over the emitter layer. The conversion efficiency of the solar cell is at least 25.7%. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the window layer. 1 fig.

Olson, J.M.; Kurtz, S.R.

1994-05-31

459

Decay Rate Of Triaxially Deformed Proton Emitters  

SciTech Connect

The decay rate of a triaxially-deformed proton emitter is calculated in a particle-rotor model, which is based on a deformed Woods-Saxon potential and includes a deformed spin-orbit interaction. The wave function of the I = 7/2- ground state of the deformed proton emitter 141Ho is obtained in the adiabatic limit, and a Green's function technique is used to calculate the decay rate and branching ratio to the first excited 2+ state of the daughter nucleus. Only for values of the triaxial angle {gamma} < 5 deg. is good agreement obtained for both the total decay rate and the 2+ branching ratio.

Davids, Cary N.; Esbensen, Henning [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

2005-04-05

460

Simulations of X band thunderstorm airborne radar observations  

NASA Astrophysics Data System (ADS)

This paper deals with simulations of thunderstorm airborne radar observations at X band ( f = 10 GHz), the frequency used by the meteorological radars of civil aviation. For this study, a radar simulator using NEXRAD data is elaborated. The various problems affecting X band (attenuation and non Rayleigh scattering) can lead to an underestimation or a false estimation of hazards. They are illustrated by a real case of severe tornadic storm in Oklahoma. It is shown that the first Mie mode of hailstones limits the large hail area detection because hail can be mistaken with non dangerous heavy rain. In addition, the problem commonly encountered with a large radar beam aperture and for long distance of observations is addressed. Ground clutter is shown to contaminate the signal of reflectivity.

Pujol, Olivier; Mesnard, Frédéric; Costes, Clémentine; Sauvageot, Henri; Bon, Nicolas; Artis, Jean-Paul

461

Properties of echo spectra observed by MST radars  

NASA Technical Reports Server (NTRS)

Turbulent scatter and Fresnel reflection are the fundamental echoing mechanisms to interpret the signals observed by Mesosphere-stratosphere-troposphere (MST) radars. Turbulent scattered echoes provide information about the turbulence structure and mean flow of the atmosphere. Observational results with VHF MST radars, however, show the importance of Fresnel reflection due to the infinite gradient of reflectivity at the edges of a scattering layer. This condition is excluded for the weak fluctuation models but it is still possible to include the observed aspect sensitivity by assuming an anisotropic structure of fluctuations. Another explanation of the aspect sensitivity observed by MST radars is advanced. Spectral estimates by the widely used periodogram were related to a four-dimensional spectrum of atmospheric fluctuations with anisotropic structure. Effects of the radar system such as antenna beam width, beam direction and Fast Fourier Transformations (FFT) data length were discussed for the anisotropic turbulent atmosphere. Echo parameters were also estimated.

Wakasugi, K.

1983-01-01

462

Crop classification using airborne radar and LANDSAT data. [Colby, Kansas  

NASA Technical Reports Server (NTRS)

Airborne radar data acquired with a 13.3 GHz scatterometer over a test-site near Colby, Kansas were used to investigate the statistical properties of the scattering coefficient of three types of vegetation cover and of bare soil. A statistical model for radar data was developed that incorporates signal-fading and natural within-field variabilities. Estimates of the within-field and between-field coefficients of variation were obtained for each cover-type and compared with similar quantities derived from LANDSAT images of the same fields. The classification accuracy provided by LANDSAT alone, radar alone, and both sensors combined was investigated. The results indicate that the addition of radar to LANDSAT improves the classification accuracy by about 10; percentage-points when the classification is performed on a pixel basis and by about 15 points when performed on a field-average basis.

Ulaby, F. T. (principal investigator); Li, R. Y.; Shanmugam, K. S.

1981-01-01

463

UAV-based Radar Sounding of Antarctic Ice  

NASA Astrophysics Data System (ADS)

We developed a compact radar for use on a small UAV to conduct measurements over the ice sheets in Greenland and Antarctica. It operates at center frequencies of 14 and 35 MHz with bandwidths of 1 MHz and 4 MHz, respectively. The radar weighs about 2 kgs and is housed in a box with dimensions of 20.3 cm x 15.2 cm x 13.2 cm. It transmits a signal power of 100 W at a pulse repletion frequency of 10 kHz and requires average power of about 20 W. The antennas for operating the radar are integrated into the wings and airframe of a small UAV with a wingspan of 5.3 m. We selected the frequencies of 14 and 35 MHz based on previous successful soundings of temperate ice in Alaska with a 12.5 MHz impulse radar [Arcone, 2002] and temperate glaciers in Patagonia with a 30 MHz monocycle radar [Blindow et al., 2012]. We developed the radar-equipped UAV to perform surveys over a 2-D grid, which allows us to synthesize a large two-dimensional aperture and obtain fine resolution in both the along- and cross-track directions. Low-frequency, high-sensitivity radars with 2-D aperture synthesis capability are needed to overcome the surface and volume scatter that masks weak echoes from the ice-bed interface of fast-flowing glaciers. We collected data with the radar-equipped UAV on sub-glacial ice near Lake Whillans at both 14 and 35 MHz. We acquired data to evaluate the concept of 2-D aperture synthesis and successfully demonstrated the first successful sounding of ice with a radar on an UAV. We are planning to build multiple radar-equipped UAVs for collecting fine-resolution data near the grounding lines of fast-flowing glaciers. In this presentation we will provide a brief overview of the radar and UAV, as well as present results obtained at both 14 and 35 MHz. Arcone, S. 2002. Airborne-radar stratigraphy and electrical structure of temperate firn: Bagley Ice Field, Alaska, U.S.A. Journal of Glaciology, 48, 317-334. Blindow, N., C. Salat, and G. Casassa. 2012. Airborne GPR sounding of deep temperate glaciers—examples from the Northern Patagonian Icefield, 14th International Conference on Ground Penetrating Radar (GPR) June 4-8, 2012, Shanghai, China, ISBN 978-1-4673-2663-6.

Leuschen, Carl; Yan, Jie-Bang; Mahmood, Ali; Rodriguez-Morales, Fernando; Hale, Rick; Camps-Raga, Bruno; Metz, Lynsey; Wang, Zongbo; Paden, John; Bowman, Alec; Keshmiri, Shahriar; Gogineni, Sivaprasad

2014-05-01

464

Roundoff noise analysis for digital Doppler processors in radar scatterometers  

NASA Technical Reports Server (NTRS)

The noise due to finite word length effects for digital Doppler processors (DPP) in radar scatterometers, is analyzed. The roundoff noise-to-signal ratio in the measurement of the radar return signal power is derived. Computer simulations which validate the analytical results are presented. The results can be used in tradeoff studies of hardware design such as number of bits required at each processing stage. The results are used in the design of a DPP for the NASA scatterometer planned to be launched in 1990.

Chi, Chong-Yung; Long, D.; Fuk, K. LI

1986-01-01

465

A traffic radar verification system based on GPS–Doppler technology  

Microsoft Academic Search

In this article, a traffic radar verification system based on the GPS–Doppler technology is described. An speedometer boarded in the target vehicle estimates its speed from the Doppler variation of the GPS satellites signals, and transmits it via radio to the police vehicle, where the radar to verify is located. In order to automate the procedure and be more effective,

Soledad Torres-Guijarro; Esteban Vázquez-Fernández; Miguel Seoane-Seoane; J. Alfonso Mondaray-Zafrilla

2010-01-01

466

Position-adaptive uav radar for low-alfitude sensing applications  

Microsoft Academic Search

Abs@uct-- A new bistatic radar concept is presented. This concept is based on signal differential path length analysis for purposes of isolating regions where targets are potentially obscured and difficult to detect via conventional techniques. Although this concept shows promise as a new area for radar research, an approximate set of initial calculations for a sample scenario are presented in

Atindra K. Mitra; Avionics Circle; Wright-Patterson AFB

2003-01-01

467

View looking down on Signcal Corps Radar (S.C.R.) 296 Station ...  

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

View looking down on Signcal Corps Radar (S.C.R.) 296 Station 5 Transmitter Building foundation from ridge, camera facing south - Fort Barry, Signal Corps Radar 296, Station 5, Transmitter Building Foundation, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

468

The HF surface wave radar WERA. Part I: Statistical analysis of recorded data  

Microsoft Academic Search

Surface wave (SW) over-the-horizon (OTH) radars are not only widely used for ocean remote sensing, but they can also be exploited in integrated maritime surveillance systems. This paper represents the first part of the description of the statistical and spectral analysis performed on sea backscattered signals recorded by the oceanographic WEllen RAdar (WERA) system. Data were collected on May 13th

Salvatore Maresca; Maria Greco; Fulvio Gini; R. Grasso; S. Coraluppi; N. Thomas

2010-01-01

469

Algoritmo Genético Aplicado à Otimização da Cobertura do Sinal Gerado por Radares Terrestres  

Microsoft Academic Search

This work treated the optimization of the territor ial radar positioning, aiming the maximum area covered by the generated si gnal. A genetic algorithm, with real representation of the genotype, was elaborated and applied to the problem. The calculations of the unions among coverings of radar signals were effected by library GPC (Generic Polygon Clipper). Results of the applications prove

Felipe Leonardo; Lobo Medeiros; Carmen Lucia; Ruybal dos Santos; Mônica Maria De Marchi; Maria José Pinto

470

Modified space-time adaptive processing for dismount detection using synthetic aperture radar  

Microsoft Academic Search

This paper presents a new adaptive radar signal processing technique for dismount detection using Synthetic Aperture Radar (SAR). The new approach uses the complex nature of the Doppler response scattering from the dismounts rotary motion to modify the conventional Space-Time Adaptive Processing (STAP). This is used for dismount detection wherein resolution is dictated by the sensor system platform. The feasibility

Ke Yong Li; Faruk Uysal; S. Unnikrishna Pillai; Linda J. Moore

2012-01-01

471

MIMO Radar Space-Time Adaptive Processing Using Prolate Spheroidal Wave Functions  

Microsoft Academic Search

In the traditional transmitting beamforming radar system, the transmitting antennas send coherent waveforms which form a highly focused beam. In the multiple-input multiple-output (MIMO) radar system, the transmitter sends noncoherent (pos- sibly orthogonal) broad (possibly omnidirectional) waveforms. These waveforms can be extracted at the receiver by a matched filterbank. The extracted signals can be used to obtain more di- versity

Chun-Yang Chen; Palghat P. Vaidyanathan

2008-01-01

472

Effect of Faraday rotation on L-band interferometric and polarimetric synthetic-aperture radar data  

Microsoft Academic Search

Electromagnetic waves traveling through the ionosphere undergo a Faraday rotation of the polarization vector, which modifies the polarization and phase characteristics of the electromagnetic signal. Using L-band (?=24 cm), polarimetric synthetic aperture radar (SAR) data from the shuttle imaging radar C (SIR-C) acquired in 1994, the author simulates the effect of a change in the Faraday rotation angle ? on

Eric J. M. Rignot

2000-01-01

473

Ground-penetrating-radar response to fracture-fluid salinity: Why lower frequencies are favorable for resolving salinity changes  

E-print Network

Time-lapse ground-penetrating-radar (GPR) surveys exploit signal-amplitude changes to monitor saline tracers in fractures and to identify groundwater flow paths. However, the relationships between GPR signal amplitude, phase, and frequency...

Tsoflias, Georgios P.; Becker, Matthew W.

2008-08-26