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1

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

2

Application of Support Vector Machines with Binary Tree Architecture to Advanced Radar Emitter Signal Recognition  

Microsoft Academic Search

Classifier design is an important issue in radar emitter signal (RES) recognition in which respondence time is a very important\\u000a and strict performance criterion. For computational efficiency, the multiclass support vector machines (SVMs) with binary\\u000a tree architecture is introduced to recognize advanced RESs. Resemblance coefficient is used to convert multi-class problems\\u000a into binary-class problems and consequently the structure of multi-class

Gexiang Zhang; Haina Rong; Weidong Jin

3

ETANN Hardware Implementation for Radar Emitter Identification.  

National Technical Information Service (NTIS)

This study investigated classification of 30 radar emitters with 16 signal features using Intel's 80170NX chip, the Electronically Trainable Analog Neural Network (ETANN). Software tools were developed to characterize the ETANN sigmoidal transfer function...

J. B. Calvin

1992-01-01

4

Online clustering algorithms for radar emitter classification.  

PubMed

Radar emitter classification is a special application of data clustering for classifying unknown radar emitters from received radar pulse samples. The main challenges of this task are the high dimensionality of radar pulse samples, small sample group size, and closely located radar pulse clusters. In this paper, two new online clustering algorithms are developed for radar emitter classification: One is model-based using the Minimum Description Length (MDL) criterion and the other is based on competitive learning. Computational complexity is analyzed for each algorithm and then compared. Simulation results show the superior performance of the model-based algorithm over competitive learning in terms of better classification accuracy, flexibility, and stability. PMID:16119259

Liu, Jun; Lee, Jim P Y; Senior; Li, Lingjie; Luo, Zhi-Quan; Wong, K Max

2005-08-01

5

Ghost signals in Allison emittance scanners  

SciTech Connect

For over 20 years, Allison scanners have been used to measure emittances of low-energy ion beams. We show that scanning large trajectory angles produces ghost signals caused by the sampled beamlet impacting on an electric deflection plate. The ghost signal strength is proportional to the amount of beam entering the scanner. Depending on the ions, and their velocity, the ghost signals can have the opposite or the same polarity as the main beam signals. The ghost signals cause significant errors in the emittance estimates because they appear at large trajectory angles. These ghost signals often go undetected because they partly overlap with the real signals, are mostly below the 1% level, and often hide in the noise. A simple deflection plate modification is shown to reduce the ghost signal strength by over 99%.

Stockli, Martin P.; /SNS Project, Oak Ridge /Tennessee U.; Leitner, M.; /LBL, Berkeley; Moehs, D.P.; /Fermilab; Keller, R.; /LBL, Berkeley; Welton, R.F.; /SNS Project, Oak Ridge /Tennessee U.

2004-12-01

6

Survey of Radar Signal Processing.  

National Technical Information Service (NTIS)

During the last decade, considerable progress has been made in radar signal processing, and this report states its present status. The three broad areas of coherent processing, noncoherent detection, and track-while-scan systems are discussed. Specificall...

G. V. Trunk

1977-01-01

7

Trends in radar signal processing  

Microsoft Academic Search

It is thought that the commercial very large scale intergration (VLSI) efforts, along with the military Very High Speed Integrated Circuits (VHSIC) program, will be of overwhelming importance in the future development of digital radar signal processing and data processing. Sucess in VLSI\\/VHSIC goals will also reduce software costs through the use of oversized low-cost signal processor hardware, for example

E. Brookner

1982-01-01

8

7. CLOSEUP FRONT VIEW OF RADAR SYSTEM EMITTER/ANTENNA (TYPICAL DEVICE ...  

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

7. CLOSE-UP FRONT VIEW OF RADAR SYSTEM EMITTER/ANTENNA (TYPICAL DEVICE PHOTOGRAPH). - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

9

Interception of LPI radar signals  

Microsoft Academic Search

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

Jim P. Lee

1991-01-01

10

Programmable Radar Signal Processing Using the Rap  

Microsoft Academic Search

This paper describes the architecture of the Raytheon Associative\\/Array Processor (RAP) and its application to real-time radar signal processing. The nature of radar computations is analyzed and parallel processing requirements are characterized. The effects of these requirements upon the design of the RAP are described. Features of the operational RAP system are discussed. Finally, an implementation of a Constant False

George R. Couranz; Mark S. Gerhardt; Charles J. Young

1974-01-01

11

Electronic intelligence: The analysis of radar signals  

NASA Astrophysics Data System (ADS)

The process of analyzing radar signals as observed by ELINT sites is discussed along with receiving equipment and methods. The fundamental character of ELINT is addressed, including the typically large range advantage the interceptor has compared to the radar's target detection range. Probability of intercept problems and the sensitivity of various types of intercept receivers are considered. Determination of SNR, which is a fundamental limit to what can be learned about a radar signal through ELINT, is treated. The measurement of radar power by ELINT, the antenna parameters of polarization, beam shape, and scanning, the pulse envelope and pulse repetition interval analysis, and the measurement of radio frequency and analysis of its stability or coherence are covered. The problem of separating radar pulse trains which are interfering at the ELINT site is addressed, and the statistical techniques used in ELINT are briefly discussed.

Wiley, R. G.

12

Data compression using SVD and Fisher information for radar emitter location  

Microsoft Academic Search

This paper presents a data compression method that can achieve a very large compression ratio for radar pulse trains that are to be used for time-difference-of-arrival\\/frequency-difference-of- arrival (TDOA\\/FDOA) multiple-platform emitter location; this method exploits pulse-to-pulse redun- dancy to get a compression ratio much higher than possible using standard compression methods. We show how to use (i) the ability of the

Mark L. Fowler; Mo Chen; J. Andrew Johnson; Zhen Zhou

2010-01-01

13

The implementation of radar signal simulator  

Microsoft Academic Search

This article describes a variety of FPGA-based radar signal generator. This system is connected to the host, binding data from the software interface, through the PCI bus transfer stored in the system. Within the FPGA to achieve DDS signal generator, and finally through the digital-analog converter output. Finally, the system resource utilization and the actual results are given.

Fuyang Zhang; Jun Wang; Yuxian Zhang; Pei Wang

2011-01-01

14

Radar Signal Processing Rulebase Partitioning.  

National Technical Information Service (NTIS)

This technical report addresses issues involved in the integration, enhancement and porting of two large knowledge-based systems, (1) Expert System Constant False Alarm Rate (ES-tFAR) and (2) The Integrated Multi-Domain Radar Demonstration (IMRD), to more...

M. Mehrotra

1995-01-01

15

Design and implemetation of a monopulse radar signal processor  

Microsoft Academic Search

Signal processor is a key part for radar seeker. In this paper, a missile-borne monopulse radar signal processor is porposed and described. According to the requirement of monopules radar, a signal processor with better commonality and versatility is designed with a FPGA&DSP structure. Firstly, some related signal processing theories are reviewed and the implementation techniques in engineering are analyzed. Secondly,

Bo Liu; Wenge Chang; Xiangyang Li

2012-01-01

16

Meteor radar signal processing and error analysis  

NASA Astrophysics Data System (ADS)

Meteor wind radar systems are a powerful tool for study of the horizontal wind field in the mesosphere and lower thermosphere (MLT). While such systems have been operated for many years, virtually no literature has focused on radar system error analysis. The instrumental error may prevent scientists from getting correct conclusions on geophysical variability. The radar system instrumental error comes from different sources, including hardware, software, algorithms and etc. Radar signal processing plays an important role in radar system and advanced signal processing algorithms may dramatically reduce the radar system errors. In this dissertation, radar system error propagation is analyzed and several advanced signal processing algorithms are proposed to optimize the performance of radar system without increasing the instrument costs. The first part of this dissertation is the development of a time-frequency waveform detector, which is invariant to noise level and stable to a wide range of decay rates. This detector is proposed to discriminate the underdense meteor echoes from the background white Gaussian noise. The performance of this detector is examined using Monte Carlo simulations. The resulting probability of detection is shown to outperform the often used power and energy detectors for the same probability of false alarm. Secondly, estimators to determine the Doppler shift, the decay rate and direction of arrival (DOA) of meteors are proposed and evaluated. The performance of these estimators is compared with the analytically derived Cramer-Rao bound (CRB). The results show that the fast maximum likelihood (FML) estimator for determination of the Doppler shift and decay rate and the spatial spectral method for determination of the DOAs perform best among the estimators commonly used on other radar systems. For most cases, the mean square error (MSE) of the estimator meets the CRB above a 10dB SNR. Thus meteor echoes with an estimated SNR below 10dB are discarded due to the potential of producing a biased estimate. The precision of the estimated parameters can then be computed using their CRB values as a proxy for the estimated variance. These errors propagate to form the instrumental errors on the height and horizontal wind measurements. Thirdly, the interferometer configuration of interferometric meteor radar system is studied. The interferometer uses the phase differences measured at different sensor pairs to determine the DOA of the meteor trail. Typically Jones cross is used in most of current meteor radar systems, such as MEDAC and SKYiMet. We have evaluated this configuration with other array geometries,such as 'T', 'L' and circular array to examine their performance on the precision of the DOA estimates. The results show that 'T' array has an overall better CRB than other geometries, while with the yagi antenna pattern as a course determination of the DOA range, the circular array performs the best with the lowest sidelobes on the spatial spectral. A Matlab based planar array design package designed for determination and visualization of the DOA estimation performance for a user designed antenna array was developed. Fourthly, based on the special configuration of the South Pole COBRA system, a low cost computational phase calibration method is proposed. Accurate knowledge of the receiver phase ofsets is another factor that can affect system performance. Lastly, the postprocessing results of the meteor echoes collected during 2005 from the South Pole COBRA system are presented. This radar system is shown to have a precision of 2m/s in the horizontal winds, an azimuth precision of 1o, and an elevation precision of 3o. Preliminary scientific results are presented to verify the effectiveness of our processing scheme, and include the seasonal variation of meteor rates as a function of height, and the vertical structure of large semidiurnal tide observed over the South Pole austral summer. The processing schemes and error analysis methods presented in this dissertation can be easily extended to other meteor radar

Kang, Chunmei

17

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

18

A Radar Signal Sorting Method Based on Immune Evolutionary Artificial Neural Network  

Microsoft Academic Search

The sorting and feature extraction of radar signal are important precondition of the recognition and location to the radars in reconnaissance areas, and they are also an important piece of content in radar countermeasure reconnaissance information analysis. Radar signal sorting is to separate the pulse signals of each radar from the complex signal pulse data received by radar countermeasure scout,

Chen Ting; Luo Jingqing; YeFei

2008-01-01

19

Signal processing possibilities for pulse radars using polarimetric information  

Microsoft Academic Search

Radars using polarimetric signal information are different from most existing radars, which work on complex scalars and are only able to measure one element of the scattering matrix of a reflecting object. This paper addresses the use of the additional polarimetric information in signal processing. Signal processing problems, their grouping, and their structure are reviewed, and the generation of features

G. Wanielik

1987-01-01

20

Investigation of topics in radar signal processing  

NASA Astrophysics Data System (ADS)

A promising image reconstruction algorithm proposed by W. Lawton for spotlight-mode synthetic aperture radar (SAR) is studied. The spatial domain image is produced through a series of convolutions and DFTs, all performed using FFTs. It is shown that the algorithm implements a form of trapezoidal-to-Cartesian interpolation followed by an FFT. A simplified back-projection algorithm is proposed for spotlight-mode SAR in which the filtered projections are obtained automatically by choosing the radar waveform to be the impulse response of the desired filter. The filtering is accomplished through the physical mechanism of the waveform reflecting off the target, which is described by a convolution. A parallel architecture is described for the back-projection of the filtered projections and its computational and memory requirements are analyzed. A basic derivation is given of bistatic spotlight-mode SAR (BSSAR). It is shown that BSSAR can be explained using the projection-slice theorem from computed tomography. The locations were found of the Fourier domain samples and examine the shape of the Fourier grid for several special cases of transmitter and receiver motions. The chirp-z interpolation algorithm, which is a promising approach to interpolation between two uniform grids with arbitrary spacings is considered. The least squares ambiguity function synthesis problem was studied, which has applications in range-Doppler radar imaging and time-frequency signal analysis. The solution is presented for least squares ambiguity function synthesis both in the continuous and discrete time-frequency domains.

Arikan, Orhan

21

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

22

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

23

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 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

24

The Signal and Interference Environment in Passive Bistatic Radar  

Microsoft Academic Search

We present a review of the properties of some signals that may be used as illuminators of opportunity in passive bistatic radar systems. It is shown that such signals are not ideal for radar purposes, though modern digital modulation formats are to be preferred, since their ambiguity performance is better and in general does not vary with time. However, with

Hugh Griffiths; Chris Baker

2007-01-01

25

UWB radars based on wavelet packet OFDM signals  

Microsoft Academic Search

Multicarrier modulation is a popular technique for ultra wideband signal design in high range resolution radars. Specially, Orthogonal Frequency Division Multiplexing (OFDM) radar signals, because of their prominent properties such as favourable ambiguity function and high spectral efficiency have been recently of interest of many researchers. The main purpose of this paper is to replace the conventional OFDM multi-carrier modulation

R. Mohseni; A. Sheikhi; M. A. Masnadi Shirazi

2008-01-01

26

Meteor radar signal processing and error analysis  

Microsoft Academic Search

Meteor wind radar systems are a powerful tool for study of the horizontal wind field in the mesosphere and lower thermosphere (MLT). While such systems have been operated for many years, virtually no literature has focused on radar system error analysis. The instrumental error may prevent scientists from getting correct conclusions on geophysical variability. The radar system instrumental error comes

Chunmei Kang

2008-01-01

27

Amplitude modulation issues in Doppler radar heart signal extraction  

Microsoft Academic Search

Medical Doppler radar research has largely been limited to obtaining respiratory and heart rates. While this information is vital for many applications, medical Doppler radar signatures carry significant other information that could lead to cardiopulmonary volume assessments, including cardiac stroke volume (SV), and cardiac output (CO). Accurate recovery of heart signal amplitude is required for these assessments. This paper presents

Olga Boric-Lubecke; Victor Lubecke; Isar Mostafanezhad

2011-01-01

28

Analysis and Emulation of FM Radio Signals for Passive Radar  

Microsoft Academic Search

Due to its high power levels provided, and its wide coverage, FM radio could be a good opportunity transmitter for passive coherent location (PCL) radar systems. In this paper we study the effectiveness of FM signals as radar waveforms by means of simulated and real data analysis. To this purpose, an emulation of FM radio transmitter is presented, whose outputs

A. Lauri; F. Colone; R. Cardinali; C. Bongioanni; P. Lombardo

2007-01-01

29

The digital signal processor for the ALCOR millimeter wave radar  

NASA Astrophysics Data System (ADS)

This report describes the use of an array processor for real time radar signal processing. Pulse compression, range marking, and monopulse error computation are some of the functions that will be performed in the array processor for the millimeter wave ALCOR radar augmentation. Real time software design, processor architecture, and system interfaces are discussed in the report.

Ford, R. A.

1980-11-01

30

Detection and Characterization of Phase-Coded Radar Signals.  

National Technical Information Service (NTIS)

This report results from a contract tasking Cranfield University (RMCS) as follows: The Grantee will investigate various mathematical concepts of detection and characterization of simulated radar signals. As detailed in the technical proposal at least fou...

E. R. Adams

2004-01-01

31

Signal Processing for Passive Radar Using OFDM Waveforms  

Microsoft Academic Search

Passive radar is a concept where illuminators of opportunity are used in a multistatic radar setup. New digital signals, like digital audio\\/video broadcast (DAB\\/DVB), are excellent candidates for this scheme, as they are widely available, can be easily decoded to acquire the noise-free signal, and employ orthogonal frequency division multiplex (OFDM). Multicarrier transmission schemes like OFDM use block channel equalization

Christian R. Berger; Bruno Demissie; Jörg Heckenbach; Peter Willett; Shengli Zhou

2010-01-01

32

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

33

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

34

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; Takeda, Kenya [NTT Co. Ltd., Chiba (Japan); Nagamatsu, Takashi [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan); Wakayama, Toshio [Mitsubishi Electric Corp., Kamakura, Kanagawa (Japan); Kimura, Iwane [Osaka Inst. of Tech., Hirakata, Osaka (Japan); Shinbo, Tetsuya [Komatsu Co. Ltd., Kanagawa (Japan)

1997-03-01

35

Optimal Transmit Signal Design for Active Sonar/Radar.  

National Technical Information Service (NTIS)

This work is concerned with the optimization of an active sonar or radar transmit signal, to maximize the probability of detecting a nonmoving point target in the presence of signal-dependent reverberation and colored ambient noise whose power spectral de...

J. H. Thanos S. M. Kay

2002-01-01

36

Advances in Radar Signal Processing Techniques  

NASA Astrophysics Data System (ADS)

Weibull-distributed clutter are reviewed. Most of the clutter received by L, S, X and Ku band radars obeys a Weibull distribution when reflectors are terrain, sea, sea-ice and rain clouds. Clutter suppression techniques for Weibull clutter are also reviewed. Especially, Weibull CFAR is emphasized.

Sekine, Matsuo; Sayama, Shuji

37

Synthetic Aperture Radar Signals: Formulations and Approaches for Data Analysis.  

National Technical Information Service (NTIS)

This report discusses principles of synthetic aperture radar, properties of radar targets, characteristics of radar imagery, statistical analysis of radar imagery, and the application of modern data analysis.

A. B. Lucero P. Swerling L. Breiman

1975-01-01

38

A Multiband Passive Radar Demonstrator  

Microsoft Academic Search

Passive radar systems that exploit signals from the plethora of RF emissions that exist in the external environment offer a number of advantages over conventional active radar system, including procurement and operational cost saving. Each emitter has its own characteristics, including waveforms, which dictate system performance. BAE Systems Advanced Technology Centre has designed and built a demonstrator system to act

Dale Gould; Robert Pollard; Carlos Sarno; Paul Tittensor

2006-01-01

39

Numerical Modeling of Doppler Radar Signals of Strombolian Eruptions  

Microsoft Academic Search

VOLDORAD is a ground-based UHF Doppler radar developed specifically for the remote sounding of volcanic eruptions. Its 23.5 cm wavelength allows us to monitor and quantify eruption intensity in real time from several km, with negligible attenuation by meteorological effects or volcanic ash. In particular, the signal can penetrate inside volcanic jets or plumes to measure the reflectivity and velocities

M. Gouhier; F. Donnadieu

2006-01-01

40

Implementation of digital pulse doppler radar signal generator and receiver  

Microsoft Academic Search

In this paper, hardware implementation of digital pulse Doppler radar signals generator and receiver based on FPGA is explained. Different performances have been noticed while using CORDIC and Hilbert transform cores for the phase shifter blocks in the implementation of generator and receiver parts. Algorithms are implemented on the Xilinx Virtex-4 FPGA. Required hardware area, resolution and amplitude of Doppler

Emrah Onat; Mahmut Serin

2011-01-01

41

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 between 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

42

On adaptive cell-averaging CFAR radar signal detection  

Microsoft Academic Search

In radar signal detection, the problem is to automatically detect a target in a nonstationary noise and clutter background while maintaining a constant probability of false-alarm. Classical detection using a matched filter receiver and a fixed threshold is not applicable due to the nonstationary nature of the background noise. Therefore, adaptive threshold techniques are needed to maintain a constant false-alarm

Mourad Barkat

1987-01-01

43

Observed Statistical Behavior of Radar Moon Echo Signals.  

National Technical Information Service (NTIS)

The observed statistical behavior of radar Moon echo signals at a transmitted radio frequency of 138.6 MHz has been analyzed. The results of the data analysis are in terms of plots for averaged Moon echoes, ensemble autocorrelation functions, and sample p...

L. J. Abella

1974-01-01

44

A flexible implementation for Doppler radar to verify various base-band array signal processing algorithms  

Microsoft Academic Search

We describe a flexible hardware system of the Doppler radar which is designed to verify various baseband array signal processing algorithms. In this work we design the Doppler radar system simulator for baseband signal processing in laboratory level. Based on this baseband signal processor, a PN-code pulse doppler radar simulator is developed. More specifically, this simulator consists of an echo

Eunjung Yang; Jonghyun Lee; Byungwook Jung; Joohwan Chun

2005-01-01

45

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

46

Knowledge-Based Radar Signal and Data Processing (Le traitement du signal et des donnees radar base sur la connaissance).  

National Technical Information Service (NTIS)

The objective of this Lecture Series was to present a state-of-the-art assessment of Knowledge-Based (KB) radar signal and data processing techniques, and thereby increase awareness of their value to the NATO scientific community. The Lecture Series cover...

2007-01-01

47

A single chip VLSI architecture for radar signal processing  

NASA Astrophysics Data System (ADS)

The problem of how much radar signal processing one can achieve with a single chip signal processor is investigated through the design of a processor architecture suitable for single chip implementation using very large scale integration (VLSI) technology. The design of the single chip processor departs from existing processor designs both in the way it is structured and the manner in which it performs computations. Major emphasis is placed on taking advantage of the parallelism and pipelining inherent in radar signal processing functions, and on novel processor architecture capable of mapping high-level computations (i.e., complex primitives such as Fast Fourier Transform) directly into hardware. The single chip design is based on state-of-the-art technology and utilizes bit-serial arithmetic and externally supplied First-In First-Out memory.

Kanopoulos, N.

48

Atmospheric Radar Signal Processing using Bivariate Empirical Mode Decomposition  

NASA Astrophysics Data System (ADS)

This paper is based upon the analysis of real-time data collected from the MST radar, NARL, CityplaceGadanki, country-regionIndia. We apply a new method, Bivariate Empirical Mode Decomposition (BEMD), to the complex time series data for estimating the Doppler frequencies and thus find the parameters like zonal (u), meridonal (v) and Vertical Wind speed (w) etc. BEMD is an algorithm for the analysis of multicomponent signals that breaks them down into a number of amplitude and frequency modulated signals, termed as Intrinsic Mode Functions (IMFs), which are basis functions for representing the signal. In a noisy signal, decomposed IMFs are a combination of IMFs of both signal and noise. By comparing with the characteristics of noise-only IMFs, we will remove the noise-dominant IMFs from the noisy signal. We reconstruct the signal with remaining IMFs and thus denoising the signal. Due to the adaptive nature of the basis functions, EMD is ideally suited than any other method like the Spectrogram, Wavelet etc for analyzing nonlinear and non-stationary processes. Initially, we apply BEMD for simulated signals such as Doppler, Bumps etc. under various noise conditions and then apply the same for the radar data. Results have been validated using Global Positioning System Sonde data. Finally, we classify the noise as Gaussian or not associated with the radar signal received form vertical as well as non vertical directions in the higher bins of the atmosphere using different parameters like Skewness, Kurtosis, Negentropy (Syntropy) and incorporating some tests such as Autocorrelation test, Power Spectral Density test, Partial Autocorrelation test.

Sreenivasulu Reddy, Thatiparthi

2012-07-01

49

Adaptive radar CFAR using signal-based suppression  

NASA Astrophysics Data System (ADS)

The primary basis for adaptive radar algorithm design is that (1) a binary hypothesis formulation with unknown parameters is an adequate test and (2) that radar interference is composed of combinations of thermal noise, self-induced clutter, and extraneous noise. This is the typical generalized likelihood formulation that yield the CFAR characteristic for the assumed conditions. Implementations have shown that such formulations yield inadequate performance in complex clutter environments. As compensation measure, a secondary CFAR process then addresses the potential violation of this assumption by large 'target-like' interference such as large clutter discretes or a large number of targets interfering with each other. In order to detect small targets, an approach based on the likelihood statistic provides a technique for optimally suppressing the neighboring large signals. Performance is characterized as a function of a generalized distance and relative signal power ratios in the joint space-time domain.

Brovko, Oleg; Nguyen, Trung T.; Whang, Yong E.

1997-10-01

50

Understanding the signal structure in DVB-T signals for passive radar detection  

Microsoft Academic Search

This paper provides a detailed overview of Digital Video Broadcasting Terrestrial (DVB-T) signal structure and the implications for passive radar systems that use these as illuminators of opportunity. In particular, we analyze the ambiguity function and make explicit its features in delay and Doppler in terms of the underlying structure of the DVB-T signal. Ambiguities will be managed via the

H. Andrew Harms; Linda M. Davis; James Palmer

2010-01-01

51

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

52

Design of a Timing Signal Generator (TSG) for RADAR Using FPGA  

Microsoft Academic Search

The paper discusses the application of VLSI technology to implement the functions of TSG of a radar system using VHDL with behavioral model, as the HDL and targeting it to a FPGA. The TSG is the heart of radar application to generate timing and control signals to operate radar in different phases like detection, tracking and acquisition, and hold mode.

Anudeepa S. Kholapure; Arvind Agarwal; Shikha Nema

2009-01-01

53

Measurement and analysis of clutter signal from GSM\\/DCS-based passive radar  

Microsoft Academic Search

Passive radars are not at all new to the radar community though they lately raised interest among researchers for some specific features that make them more appealing than classic active radar systems. In fact, having the TX and RX located at two different positions, and the adoption of signals carrying other kinds of information such as GSM (either classical or

Antonio De Maio; G. Foglia; Nicola Pasquino; Michele Vadursi

2008-01-01

54

Signal processing for through wall moving target tracking by M-sequence UWB radar  

Microsoft Academic Search

In this paper, through wall moving target tracking by UWB radar is described as a complex process with all required phases of radar signal processing. For particular phases of that process, i.e. for raw radar data preprocessing, background subtraction, detection, trace estimation, localization and tracking itself, the phase significance and its corresponding representative methods are outlined. The complete process is

J. Rovnakova; M. Svecova; D. Kocur; Trung Thanh Nguyen; J. Sachs

2008-01-01

55

Topography adjacent to Signal Corps Radar (S.C.R.) 296 Station 5, ...  

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

Topography adjacent to Signal Corps Radar (S.C.R.) 296 Station 5, showing conditions before construction, May 28, 1943, this drawing shows the Bonita Ridge access road retaining wall and general conditions at Bonita Ridge before the construction of Signal Corps Radar (S.C.R.) 296 Station 5 - Fort Barry, Signal Corps Radar 296, Station 5, Transmitter Building Foundation, Point Bonita, Marin Headlands, Sausalito, Marin County, CA

56

Signal Analysis Van - A radar system data acquisition and processing tool  

NASA Astrophysics Data System (ADS)

An advance in radar technology achieved in the U.S. Army Missile Command for the analysis of radar performance and the design of radar signal processors is discussed. It is noted that the concept is based on a Radar Technology Signal Analysis Van (SAV) which contains special purpose electronics and computer equipment. The unique system provides the first capability to analyze the exact performance of radars in the field by recording full-bandwidth, full-dynamic range video returns in a live environment. During optimization of radar designs, the real-world data are played into signal processor emulations in the laboratory. It is pointed out that these techniques for analyzing and designing high performance radars had not previously been possible.

Cash, T. W.; Owen, L. B.

57

Soil Moisture Profile Effect on Radar Signal Measurement  

PubMed Central

The objective of this paper is to analyze the behaviour of a backscattered signal according to soil moisture depth over bare soils. Analysis based on experimental vertical moisture profiles and ASAR/ENVISAT measurements has been carried out. A modified IEM model with three permittivity layers (0-1cm, 1-2cm, 2-5cm) has been developed and used in this study. Results show a small effect of moisture profile on the backscattered signal (less than 0.5dB). However, measurements and simulations have provided a more detailed insight into the behaviour of the radar signal and have shown that it was important to consistently use the same protocol when performing ground truth measurements of soil moisture.

Le Morvan, Aurelie; Zribi, Mehrez; Baghdadi, Nicolas; Chanzy, Andre

2008-01-01

58

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

59

Sea and air moving target measurements using a GSM based passive radar  

Microsoft Academic Search

A passive radar is essentially a receiver-only radar that does not transmit signals; it only receives and thus operates independently without the direct synchronization from the non-cooperative illuminator. GSM base station transmitter as the illuminator of opportunity in a passive radar offers a covert means of uninterrupted surveillance where the major advantage is that the emitters of such transmissions are

Danny K. P. Tan; Hongbo Sun; Yilong Lu

2005-01-01

60

Signal extraction using Compressed Sensing for passive radar with OFDM signals  

Microsoft Academic Search

Passive radar is a concept where possibly multiple non-cooperative illuminators are used in a multi-static setup. A freely available signal, like radio or television, is decoded and used to identify moving airborne targets based on their Doppler shift. New digital signals, like Digital Audio\\/Video Broadcast (DAB\\/DVB), are excellent candidates for this scheme, as they are widely available, can be easily

Christian R. Berger; Shengli Zhou; Peter Willett

2008-01-01

61

A new method of HRR profile formation based on multiple radars LFM signal fusion  

Microsoft Academic Search

In this paper, the authors present a new method of HRR profile formation based on the LFM signal fusion of the multiple radars with multiple frequency bands. The principle of the multiple radars signal fusion improving the range resolution is analyzed. During the fusion process, the B-splines interpolation and an entropy-minimization principle based phase compensation algorithm are applied. The theoretical

Wang Cheng; Hu Wei-dong; Du Xiao-yong; Yu Wen-xian

2005-01-01

62

Real-time radar signal processing for autonomous aircraft landing  

NASA Astrophysics Data System (ADS)

Landing in poor weather is a crucial problem for the air transportation system. To aid the pilots for these conditions several solutions have been suggested and/or implemented including instrument landing systems (ILS) and microwave landing systems (MLS) that put the responsibility of the landing to a large extent in the hands of the airport facilities. These systems even though useful are not available due to their high costs even in a few major metropolitan airports. This shortcoming has generated interest in providing all weather capabilities not on the landing facility but on the vehicle itself. The Synthetic Vision System Technology Demonstration sponsored by the United States Federal Aviation Administration (FAA) and the U.S. Air Force represents an effort to respond to the above needs. In this paper we present a summary of a typical synthetic vision system. This system consists of a scanning 35 GHz radar, a scanning antenna, a signal/image processor and a head up display (HUD). The pilot is presented a final perspective image of the scene sensed by the radar with associated flight guidance symbology. This system is implemented in real time hardware and has been undergoing tower and flight testing under a variety of weather conditions since early 1992.

Sadjadi, Firooz A.; Helgeson, Michael A.; Radke, Jeffrey D.; Stein, Gunter

1993-11-01

63

Programmable AND-CFAR signal detector design and its FPGA prototyping for FMCW radar systems  

Microsoft Academic Search

This paper presents the digital signal processor design for constant-false-alarm-rate (CFAR) signal detection in a frequencymodulated-continuous-waveform (FMCW) radar system. It is capable of identifying the beat signal from the spectrum so as to calculate the distance between the radar and the ground. The proposed CFAR signal detection design is an enhancement of the basic AND-CFAR architecture, which combines the algorithms

Cheng-Ru Hong; Yin-Tsung Hwang; Wei-Chieh Hsu; Chi-Ho Chang; Jui-Chi Huang; Ho-En Liao

2011-01-01

64

A NEW ARCHITECTURE OF UWB RADAR UTILIZING MICROWAVE CHAOTIC SIGNALS AND CHAOS SYNCHRONIZATION  

Microsoft Academic Search

Abstract—In this paper, we present a new scheme for the realization of a wide-band chaotic RADAR system. The remarkable characteristics of such scheme are: (1) Wide-band chaotic signal generated from microwave chaotic Colpitts oscillator is directly used as the RADAR signal; (2) Chaos synchronization is used to recover the chaotic signal from the back-scattered signal by targets; (3) The intrinsic

Shan Qiao; Zhi-Guo Shi; K. S. Chen; T. Jiang

2007-01-01

65

Radar Signal Processing in Instrumentation and Measurement Technology  

NASA Astrophysics Data System (ADS)

It is reported that various radar clutter obey a Weibull distribution. To suppress such Weibull-distributed clutter, Weibull CFAR techniques are applied to data taken by an S-band radar. The results show the usefulness of Weibull CFAR.

Sekine, Matsuo

66

Feasibility analysis of GSM signal for passive radar  

Microsoft Academic Search

Passive radar makes use of an 'illuminator of opportunity' already present in the environment for other purposes (TV transmission, broadcast systems, etc) to detect targets as well as estimating target parameters. This radar has the merit of being a completely covert radar system, which does not advertise the presence of either the receivers or transmitting stations. One such existing radio

Danny K. P. Tan; Hongbo Sun; Yilong Lu; Weixian Liu

2003-01-01

67

Bistatic coherent laser radar signal-to-noise ratio.  

PubMed

We investigate the signal-to-noise ratio (SNR) for a bistatic coherent laser radar (CLR) system. With a bistatic configuration, the spatial resolution is determined by the overlap of the transmit beam and the virtual backpropagated local oscillator beam. This eliminates the trade-off between range resolution and the bandwidth of the transmitted pulse inherent in monostatic systems. The presented analysis is completely general in that the expressions can be applied to both monostatic and bistatic CLR systems. The heterodyne SNR is computed under the assumption of untruncated Gaussian optics and untruncated Gaussian beam profiles. The analysis also includes the effects of refractive turbulence. The results show that, for maximum SNR, small transmit and local oscillator beam profiles (e-1 intensity radius) are desired. PMID:11921808

Magee, Eric P; Kane, Timothy J

2002-03-20

68

Virtual hyperbolic metamaterials for manipulating radar signals in air  

NASA Astrophysics Data System (ADS)

Microwave beam transmission and manipulation in the atmosphere is an important but difficult task. One of the major challenges in transmitting and routing microwaves in air is unavoidable divergence because of diffraction. Here we introduce and design virtual hyperbolic metamaterials (VHMMs) formed by an array of plasma channels in air as a result of self-focusing of an intense laser pulse, and show that such structure can be used to manipulate microwave beams in air. Hyperbolic, or indefinite, metamaterials are photonic structures that possess permittivity and/or permeability tensor elements of opposite sign with respect to one another along principal axes, resulting in a strong anisotropy. Our proof-of-concept results confirm that the proposed virtual hyperbolic metamaterial structure can be used for efficient beam collimation and for guiding radar signals around obstacles, opening a new paradigm for electromagnetic wave manipulation in air.

Kudyshev, Zhaxylyk A.; Richardson, Martin C.; Litchinitser, Natalia M.

2013-10-01

69

Virtual hyperbolic metamaterials for manipulating radar signals in air.  

PubMed

Microwave beam transmission and manipulation in the atmosphere is an important but difficult task. One of the major challenges in transmitting and routing microwaves in air is unavoidable divergence because of diffraction. Here we introduce and design virtual hyperbolic metamaterials (VHMMs) formed by an array of plasma channels in air as a result of self-focusing of an intense laser pulse, and show that such structure can be used to manipulate microwave beams in air. Hyperbolic, or indefinite, metamaterials are photonic structures that possess permittivity and/or permeability tensor elements of opposite sign with respect to one another along principal axes, resulting in a strong anisotropy. Our proof-of-concept results confirm that the proposed virtual hyperbolic metamaterial structure can be used for efficient beam collimation and for guiding radar signals around obstacles, opening a new paradigm for electromagnetic wave manipulation in air. PMID:24084779

Kudyshev, Zhaxylyk A; Richardson, Martin C; Litchinitser, Natalia M

2013-10-01

70

A 55-GHz-Small-Signal-Bandwidth Switched Emitter Follower in InP Heterojunction Bipolar Transistors  

NASA Astrophysics Data System (ADS)

Two Switched Emitter Follower circuits are designed and fabricated with a 320 GHz-Ft-InP Double Heterojunction Bipolar Transistors process (DHBT). The first one uses a 10?m emitter length (T10) transistors and the second a 7?m emitter length (T7) transistors. Measurements show a-3dB small signal bandwidth up to 55GHz with a sufficient isolation larger than 30dB. An extensive analysis as function of sizes, hold capacitor and bias conditions were performed by simulations in order to obtain a good tradeoff between bandwidth, isolation and linearity.

Deza, Julien; Ouslimani, Achour; Konczykowska, Agnieszka; Kasbari, Abed-Elhak; Godin, Jean; Pailler, Gwennolé

71

Radar/sonar signal design for bounded Doppler shifts  

NASA Astrophysics Data System (ADS)

In many detection and estimation problems, Doppler frequency shifts are bounded. For clutter or multipath that is uniformly distributed in range and symmetrically distributed in Doppler shift relative to the signal, detectability of a point target or a communication signal is improved by minimizing the weighted volume of the magnitude-squared autoambiguity function. When clutter Doppler shifts are bounded, this volume is in a strip containing the range axis on the range-Doppler plane. For scattering function estimation, e.g., for weather radar, Doppler flow meters, and distributed target classifiers, it is again relevant to minimize ambiguity volume in a strip. Strip volume is minimized by using a pulse train, but such a signal has unacceptably large range sidelobe for most applications. Other waveforms that have relatively small sidelobe level within a strip on the range-Doppler plane, as well as small ambiguity volume in the strip, are obtained. The waveforms are composed of pulse pairs that are phase modulated with Golay complementary codes.

Altes, R. A.

1982-07-01

72

Computer-aided methods of the LPI radar signal detection and classification  

NASA Astrophysics Data System (ADS)

The paper describes a possible structure of the LPI radar signal classification algorithm based on using a computer system with elements of the artificial intelligence (AI). Such an algorithm uses a combination of different signal processing tools such as the Wigner-Ville Distribution, the Wavelet Transform and the Cyclostationary Signal Analysis. The efficiency of these transformations with respect to different kinds of digital LPI radar signal modulation is considered. For a final classification and parameters extraction on the base of time-frequency or bifrequency representation the artificial intelligence methods can be used. One of the possible approaches to solving the radar signal classification problem is to use a proposed in the paper algorithm which consists of several steps: time-frequency or bifrequency transformations, a noise reduction procedure with using a two-dimensional filter, the RBF artificial neural network (NN) probability density function estimator which extracts the feature vector used for the final radar signal classification without an operator.

Grishin, Yury; Janczak, Dariusz

2008-01-01

73

Wavelets: multiresolution signal representation with applications to image, speech, radar, and other signal coding  

NASA Astrophysics Data System (ADS)

The problem of designing wavelets which are most appropriate for applications to multiresolution coding of image, speech, radar and other signals is addressed. The effects of regularity and zero moments on the design of wavelets and filter banks used to realize these wavelet decompositions are discussed, and insights pointed out. The use of vector quantization with wavelet transforms will be discussed. It is observed how wavelet decompositions are a compromise between optimality and complexity, where the optimality is determined from the minimization of bit rate and distortion, using rate distortion theory. The problem of designing wavelets yielding linear phase filtering, important for applications such as television coding and radar, is discussed and a number of approaches to solutions are described. These include the use of biorthogonal rather than orthogonal bases for wavelets which are realizable by general perfect reconstruction filter banks in which the analysis and synthesis filters are not time-reversed versions of each other. Methods for designing linear phase filters are briefly discussed and referenced. In the discussion on applications to radar signals, the relation of wavelet theory to a special signal called a chirplet is noted. Some connections of wavelets to splines and cardinal series are noted. Finally, wavelets which almost meet the uncertainty principle bound with equality are described.

Sablatash, Mike

1992-10-01

74

A new digital signal processor for Doppler radar cardiopulmonary monitoring system  

Microsoft Academic Search

Remote sensing and monitoring of cardiopulmonary activities based on direct conversion Doppler radar shows promise in medical and security applications. For accurate sensing, demodulation of the quadrature outputs of a direct-conversion Doppler radar is a great challenge. A digital signal processor based on Kalman filtering and principal component combining of quadrature channels is suggested. Rate detection ability and success ratio

Mohammad Shaifur Rahman; Byung-Jun Jang; Ki-Doo Kim

2008-01-01

75

State estimation of projectiles based on Doppler radar signals using EKF and UKF  

Microsoft Academic Search

In this paper we compare two methods that lead to distance and velocity estimation of fast moving objects at very close ranges based on Doppler radar signals in real time applications. The first goal of this work has been to find an algorithm and the adjustments to get stable and precise actual state estimations using a low power Doppler radar

Sonja Podjawerschek; Emil Spahn; Michael Brodmann; Joachim Horn

2010-01-01

76

A Novel Sorting Method of Radar Signals Based on Support Vector Clustering and Delaminating Coupling  

Microsoft Academic Search

Modern electronic warfare faces complex and dense pulses environments, which brings a severe challenge to radar signal sorting. A novel sorting method is presented based on delaminating coupling and support vector clustering (SVC) in this paper. The 3-dimension feature information is composed of direction of arrival, radio frequency and pulse width in this method which sorts radar pulse sequences for

Qiang Guo; Xingzhou Zhang; Zheng Li

2006-01-01

77

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

78

The study of signal simulation based on the passive radar seeker  

Microsoft Academic Search

This paper presents a method of video signal simulation for the passive radar seeker. The simulation platform has been built up, which gives evidence to the typical warfare environment, the experimental results show that the model of the passive radar seeker could be reliable and effective.

Li Shasha; Si Xicai; Jia Zongsheng

2008-01-01

79

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

80

The design of a PC-based, low-cost radar video signal generator  

Microsoft Academic Search

In the field of electronic warfare (EW), the development, test, validation, and debugging of radar warning receiver (RWR) hardware and software in the laboratory necessitates the simulation of radar threat signals. This requirement often leads to the development of expensive, high-fidelity, radio frequency (RF) simulators. Because they are expensive, they are scarce. They are also often hard to configure, operate,

D. W. Olsen; M. J. Willis

1997-01-01

81

Radar measurement of L-band signal fluctuations caused by propagation through trees  

NASA Astrophysics Data System (ADS)

Fluctuations of an L-band, horizontally polarized signal that was transmitted from the ground through a coniferous forest canopy to an airborne radar are examined. The azimuth synthetic aperture radar (SAR) impulse response in the presence of the measured magnitude fluctuations shows increased sidelobes over the case with no trees. Statistics of the observed fluctuations are similar to other observations.

Durden, Stephen L.; Klein, Jeffrey D.; Zebker, Howard A.

1991-10-01

82

Doppler Signal Analysis and Processing Techniques for Modified 'Porcupine' C-Band Pulse Doppler Radar.  

National Technical Information Service (NTIS)

The report deals primarily with various doppler signal processing techniques for the Porcupine Weather Radar System. Continuing emphasis is placed on digital data reduction techniques including the fast Fourier transform method of spectral analysis. Pract...

T. Berger E. G. Cox H. L. Groginsky J. M. Kovalik G. A. Works

1968-01-01

83

Automatic signal processing of front monitor radar for tunneling machines  

Microsoft Academic Search

It is planned to install a front monitor 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 does not constitute a hyperbola as is the

Toru Sato; Ken-ya Takeda; Takashi Nagamatsu; Toshio Wakayama; Iwane Kimura; Tetsuya Shinbo

1997-01-01

84

On the optimum range resolution of radar signals in noise  

Microsoft Academic Search

Optimum radar resolution is recognized to be a problem in distinguishing between different possible target configurations. Radar reception systems which perform optimum range resolution are then designed using the principles of statistical decision theory. In particular, the design of the optimum resolution system is carried out for a squared-error loss function, modified to provide extra penalties for wrong guesses about

N. Nilsson

1961-01-01

85

Performance of random OFDM radar signals in deception jamming scenarios  

Microsoft Academic Search

The paper examines the performance of randomly generated OFDM waveforms in presence of deception jamming. The scenario of interest uses OFDM waveforms for synthetic aperture radar (SAR) imaging of a target area into which a digital radio frequency memory (DRFM) repeat jammer has been introduced. The jammer attempts to introduce false targets into the final image by replicating the radar

Jonathan Schuerger; Dmitriy Garmatyuk

2009-01-01

86

Adaptive radar CFAR using signal-based suppression  

Microsoft Academic Search

The primary basis for adaptive radar algorithm design is that (1) a binary hypothesis formulation with unknown parameters is an adequate test and (2) that radar interference is composed of combinations of thermal noise, self-induced clutter, and extraneous noise. This is the typical generalized likelihood formulation that yield the CFAR characteristic for the assumed conditions. Implementations have shown that such

Oleg Brovko; Trung T. Nguyen; Yong E. Whang

1997-01-01

87

Analogue TV Signal-Based Passive Radar onboard Single Air-Platform  

Microsoft Academic Search

An analogue TV signal-based passive radar onboard single air-platform can be considered as a bistatic CW radar. This implementation suffers, however, considerable range ambiguities due to the time-varying form of analogue TV video signal, when it detects and tracks the target by exploiting the AOA and TDOA information in echoes of targets from transmitter of opportunity. In this paper we

Sun Long-xiang; Liu jian; Chen Si-xing

2006-01-01

88

High speed multi processor architecture based software driven radar signal processor using DSP chips  

NASA Astrophysics Data System (ADS)

The paper describes the design and development of a high speed radar signal processor architecture, based on floating point DSP chips. Totally software-driven, four such chips in a data-partitioned multiprocessing architecture under a controller perform CPI-based signal processing algorithms of the MTD type to meet the real-time performance requirements of a medium range surveillance radar. Sensor performance improvement on account of greatly reduced computational errors has been observed.

Rajendran, S.; Souriraj, S. J.; Raghavan, R.; Nair, R. M.

89

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.

90

Advanced Radar Signal and Data Processing (Le traitement avance du signal et des donnees radar) (CD-ROM).  

National Technical Information Service (NTIS)

Radar is an important sensor characterized by day/night all-weather operation capability. A key feature of radar is the ability of reconnaissance, surveillance of a wide area with target acquisition (RSTA). In addition it offers the potential of moving ta...

2006-01-01

91

Group-complement code signal and its radar ambiguity function  

NASA Astrophysics Data System (ADS)

A group-complement code (GCC) is a type of artificial noise, generally a code group consisting of a multigroup equal length subcode with each of its elements being coded in accordance with frequency, phase, and amplitude. After the screened group-complement codes are received by using auto-correlation method, the sum of all subcode auto-correlation function is characterized by total complementarity. If used in radar, the group-complement code forms an artificial noise radar. If used in communication, it forms an artificial noise communication. This paper will mainly focus on explaining the domains, mathematical model, and radar ambiguity function of the group-complement code.

Zhong, Chi-Rui

92

Application of the Hilbert transform to Doppler radar signals from a hypervelocity gun  

Microsoft Academic Search

A computer program is described that processes a Doppler radar signal to provide the position, velocity, and acceleration histories of a model in the barrel of a hypervelocity gun. The program uses the Hilbert transform as obtained via the Fourier transform. Algorithms for dealing with poor signal quality are described. Results from actual and simulated signals are presented. It is

Robert W. Cayse

1988-01-01

93

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

94

Method for the processing of the reception signal of a deramp type synthetic aperture radar  

US Patent & Trademark Office Database

A Deramp type radar used in synthetic aperture radar for radar imaging transmits coherently repeated linear frequency-modulated pulses and carries out a sort of pulse compression in reception by demodulation of the echo signals received by means of a frequency ramp that reproduces all or part of a transmitted pulse, and by a Fourier transform performed in range. The application to a Deramp type radar signal of a standard SAR processing is disturbed by the fact that, in this signal, the effectively demodulated part of an echo signal due to a target has a position with respect to this echo signal and a duration that are variable as a function of the distance from the target to the radar. The proposed method makes it possible to eliminate this disturbance by means of a particular choice of a common temporal support used for the demodulation of the signals of all the targets of the useful swath and a phase correction applied to the level of the pulse response of the image focusing filter of the SAR processing. Secondarily, a second phase correction can be applied to the complex reflection coefficients obtained for the dots of the image at the end of the SAR processing.

2000-06-06

95

Computer-Aided Design of Radar Signals using the Ambiguity Functions.  

National Technical Information Service (NTIS)

The report documents the development of a computer-aided design program for determining the resolving power of radar signals from their ambiguity functions. The program computes the ambiguity function for any finite signal envelope and displays it on a gr...

J. V. Medea

1973-01-01

96

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

97

Signal Processing in Multisite UWB Radar Devices for Searching Survivors in Rubble  

Microsoft Academic Search

The use of ultra wideband multisite radar devices (UWB MSRDs) with two antennas separated by about 1...1.5 m for searching survivors in rubble is very prospective. Optimised signal processing in such UWB MSRD is considered, which has to solve two principal problems: 1) detection of very weak signals reflected from a moving human chest due to breathing against strong clutter

Victor Chernyak

2006-01-01

98

Suppressing interfering scattered signals in swept-frequency radar measurements by using frequency domain Wiener filtering  

NASA Astrophysics Data System (ADS)

A novel approach to the reduction of scattered, interfering signals that corrupt measurements of the signal backscattered from radar targets of interest is being developed. It is being explored with sphere measurements in an indoor microwave radar range. This method is based on the concept of Wiener filtering (which minimizes the difference between the signal plus noise and the desired signal in the time domain). In contrast to the traditional Wiener filter, in which the time domain error between two sequences are minimized, the approach reported uses the frequency domain phasor amplitudes of a swept frequency signal. It minimizes the difference (least-mean-square-magnitude) between the signal-plus-noise and the signal complex phasors, across the entire spectrum.

Weissman, David E.; Staton, Leo D.

99

The Coupling of Vertical Velocity and Signal Power Observed with the SOUSY VHF Radar.  

NASA Astrophysics Data System (ADS)

The perturbations to the static stability (and hence to the radar reflectivity) and to the velocity in a vertically propagating gravity wave are correlated, and the sign of the correlation depends on whether the wave is propagating upward or downward. The wave-induced correlation between radar reflectivity and vertical velocity is the basis of a hypothesis to explain the downward bias in long-term averages of the vertical velocity seen at extratropical sites by wind profiler radars, and for predictions of biases in the horizontal wind speeds and in the vertical momentum flux seen by profiler radars. In this study, the hypothesis that mean vertical velocity is related to the correlation between perturbations to vertical velocity and signal power is tested. Observations with very high time and vertical resolution from the SOUSY VHF radar are used. It is found that the mean vertical velocity in the midtroposphere (2.4-6.3 km) is downward (upward) when the perturbations to vertical velocity and to backscattered power over this height range are negatively (positively) correlated. Similar results are found during summer and winter periods. Results are also similar when the radar was upwind of the nearby Harz Mountains compared to when the radar was downwind of the mountains.

Nastrom, G. D.; Rüster, R.; Schmidt, G.

1998-01-01

100

Efficiency of four-plasmon interactions in the reflection of a radar signal from the sun  

SciTech Connect

The question of whether processes of scattering, of the type t+sigma..-->..t'+sigma', of electromagnetic waves on intrinsic turbulence of the coronal plasma are able to provide the power of a radar signal reflected from the sun is discussed. Expressions for the effective cross section are obtained in the case of scattering of an electromagnetic signal on Langmuir pulsations of an isotropic coronal plasma and in the case of scattering on ion-acoustic turbulence. Numerical estimates show the possibility of explaining solar radar data using the mechanism of four-plasmon interaction of electromagnetic radiation with turbulent pulsations of the coronal plasma.

Gerasimova, N.N.

1979-11-01

101

Tracking radar advanced signal processing and computing for Kwajalein Atoll (KA) application  

NASA Astrophysics Data System (ADS)

Two means are examined whereby the operations of KMR during mission execution may be improved through the introduction of advanced signal processing techniques. In the first approach, the addition of real time coherent signal processing technology to the FPQ-19 radar is considered. In the second approach, the incorporation of the MMW radar, with its very fine range precision, to the MMS system is considered. The former appears very attractive and a Phase 2 SBIR has been proposed. The latter does not appear promising enough to warrant further development.

Cottrill, Stanley D.

1992-11-01

102

WiMAX signal generation based on MIMO-OFDM testbed for passive radar application  

Microsoft Academic Search

In order to analyze the ambiguity function of WiMAX signals and evaluate their suitability for passive radar, the first step should be the generation of WiMAX transmission signal, including random data generation, modulation, Space Time Block Coding (STBC), preamble generation for synchronization and channel estimation, frame combination and Orthogonal Frequency Division Multiplexing (OFDM) modulation. In this paper, WiMAX signal generation

Qing Wang; Chunping Hou; Yilong Lu

2009-01-01

103

SHUTTLE IMAGING RADAR: PHYSICAL CONTROLS ON SIGNAL PENETRATION AND SUBSURFACE SCATTERING IN THE EASTERN SAHARA.  

USGS Publications Warehouse

It is found that the Shuttle Imaging Radar A (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. 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, called radar imaging depth, was documented in the field to be a maximum of 1. 5 m, or 0. 25 times the calculated skin depth, for the sediment blanket. The radar imaging depth is estimated to be between 2 and 3 m for active sand dune materials.

Schaber, Gerald, G.; McCauley, John, F.; Breed, Carol, S.; Olhoeft, Gary, R.

1986-01-01

104

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

NASA Astrophysics Data System (ADS)

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 MHz during daytime. Since the ionospheric plasma is a dispersive medium for radio waves, it introduces phase distortions in radar signal. To increase the depth of sounding, a radar should operate at frequencies as low as possible. However, the lowest radar operating frequency is determined by the critical ionospheric frequency. In addition, the requirement of high depth resolution leads to usage of ultra wideband (UWB) chirp signals with relative bandwidth about several tens per cent. Under these conditions, phase distortions due to wave dispersion in the ionosphere are especially noticeable. Therefore, signal processing scheme should include some procedure for their correction. The problem of elimination of phase distortions introduced by the Martian ionosphere into a chirp radar signal %effect was considered. Several versions of adaptive schemes were proposed for compensating distortions. These techniques are appropriate both for on-board and on-the-ground data processing schemes. Approaches to incorporation of %Advantages of using additional information sources into signal processing scheme, in particular, data on the ionosphere critical frequency obtained with the same radar, were analyzed. All the proposed algorithms were tested numerically . Stability to additive measurement noise was investigated. It was shown that the proposed algorithms ensure the accuracy of distortion compensation necessary for detecting subsurface horizons situated at a depth of hundreds of meters to several kilometers. Although the study presented here relates mostly to Martian ionosphere, nevertheless most obtained results can be applied to ionospheres of other celestial bodies.

Ilyushin, Ya. A.; Kunitsyn, V. E.

105

Joint DOD/DOA estimation in MIMO radar exploiting time-frequency signal representations  

NASA Astrophysics Data System (ADS)

In this article, we consider the joint estimation of direction-of-departure (DOD) and direction-of-arrival (DOA) information of maneuvering targets in a bistatic multiple-input multiple-output (MIMO) radar system that exploits spatial time-frequency distribution (STFD). STFD has been found useful in solving various array processing problems, such as direction finding and blind source separation, where nonstationary signals with time-varying spectral characteristics are encountered. The STFD approach to array processing has been primarily limited to conventional problems for passive radar platform that deals with signal arrivals, while its use in a MIMO radar configuration has received much less attention. This paper examines the use of STFD in MIMO radar systems with application to direction finding of moving targets with nonstationary signatures. Within this framework, we consider the use of joint transmit and receive apertures for the improved estimation of both target time-varying Doppler signatures and joint DOD/DOA. It is demonstrated that the STFD is an effective tool in MIMO radar processing when moving targets produce Doppler signatures that are highly localized in the time-frequency domain.

Zhang, Yimin D.; Amin, Moeness G.; Himed, Braham

2012-12-01

106

Geometrical and signal processing aspects using a bistatic hitchhiking radar system  

Microsoft Academic Search

Bistatic hitchhiking radar system concepts have been object for extensive research both for military and civilian applications. Hitchhiking systems are in principle easy to construct and can be used without introducing any interference, or being seen by a possible enemy. This paper addresses how to handle the geometry such systems are faced together with using proper signal analysis strategies for

O. Overrein; Karl E. Olsen; S. Johnsrud; P. K. Sornes; T. Johnsen; J. Navarro; V. Sahajpal; R. O. Stemland

2005-01-01

107

An adaptive multimicroprocessor array computing structure for radar signal processing applications  

Microsoft Academic Search

This paper describes an array processor designed for signal processing in radar applications. The processor consists of a large number of microprocessor-based processing elements and is designed to be adaptive in real-time processing requirements. The processing problem has been considered to have a quite specific data organization and data rate which can be exploited in the architectural design. Parallel processing

C. V. W. Armstrong; H. M. Ahmed; N. A. Brans; E. Fathi

1979-01-01

108

Frequency Dependence of the Soil Electromagnetic Properties Derived from Ground-Penetrating Radar Signal Inversion  

Microsoft Academic Search

The accuracy at which the subsurface electromagnetic properties can be identified from full wave inversion of ground penetrating radar (GPR) signals relies on the appropriateness of the model describing their frequency dependence. In this paper, we focus on the characterization of the frequency dependence of the dielectric permittivity and electric conductivity of a sandy soil subject to different water contents

Sébastien Lambot; Idesbald van den Bosch; Benoit Stockbroeckx; Pascal Druyts; Marnik Vanclooster; Evert Slob

2005-01-01

109

A digital signal processor for Doppler radar sensing of vital signs  

Microsoft Academic Search

A signal processor for the determination of respiration and heart rates in Doppler radar measurements is described. The processor can reliably calculate both rates for a subject at distances as large as 2 m. The rate determination is based on autocorrelation and uses several enhancement techniques, including a center clipper. Several representative results are included to show the future potential

B. Lohman; O. Boric-Lubecke; V. M. Lubecke; P. W. Ong; M. M. Sondhi

2002-01-01

110

An advanced digital signal processor for the HRR polarimetric MMW active guidance radar  

Microsoft Academic Search

Polarimetric CFAR detection procedures are first outlined. An advanced digital signal processor used for MMW polarimetric HRR active precision guiding radar is configured that involves a preamplifier and filter, a spectral analyzer and a DSP-based polarimetric detector\\/discriminator to seek and track ground targets in surface clutter. A fuzzy relative optimal state (FROS) of a processor is conceptualized concerning the compromise

Yong Rin; Benchao Sie; Lui Yongtan

1993-01-01

111

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

112

On adaptive cell-averaging CFAR (Constant False-Alarm Rate) radar signal detection  

Microsoft Academic Search

In radar signal detection, the problem is to automatically detect a target in a nonstationary noise and clutter background while maintaining a constant probability of false alarm. Classical detection using a matched filter receiver and a fixed threshold is not applicable due to the nonstationary nature of the background noise. Therefore, adaptive threshold techniques are needed to maintain a constant

Mourad Barkat; Pramod K. Varshney

1987-01-01

113

Signal Processor Interface Simulation of the AN/SPY-1A Radar Controller.  

National Technical Information Service (NTIS)

This thesis reports on the design and implementation of a simulation of the Signal Processor Interface to the AN/SPY-1A Phased Array Radar Controller. Inherent to the simulation is the development of a representative time sensitive database of the targeti...

T. B. Kersh

1983-01-01

114

DVB-T Signal Cross-Ambiguity Functions Improvement for Passive Radar  

Microsoft Academic Search

This paper proposes a digital video broadcasting-terrestrial (DVB-T) signal cross-ambiguity functions (CAF) improvement technique by modifying the guard interval and the pilots in the direct channel, which can remove the unwanted deterministic peaks in the DVB-T passive radar effectively. The key of CAF improvement is the pilots modification directly on the pilot carriers based on the DVB-T signal (fs=64\\/7 MHz),

Zhiwen Gao; Ran Tao; Yongfeng Ma; Tao Shao

2006-01-01

115

Multi-PRI Signal Processing for the Terminal Doppler Weather Radar. Part I: Clutter Filtering  

Microsoft Academic Search

Multiple pulse repetition interval (multi-PRI) transmission is part of an adaptive signal transmission and processing algorithm being developed to aggressively combat range-velocity ambiguity in weather radars. In the past, operational use of multi-PRI pulse trains has been hampered due to the difficulty in clutter filtering. This paper presents finite impulse response clutter filter designs for multi-PRI signals with excel- lent

John Y. N. Cho; Edward S. Chornoboy

2005-01-01

116

Photonic generation and independent steering of multiple RF signals for software defined radars.  

PubMed

As the improvement of radar systems claims for digital approaches, photonics is becoming a solution for software defined high frequency and high stability signal generation. We report on our recent activities on the photonic generation of flexible wideband RF signals, extending the proposed architecture to the independent optical beamforming of multiple signals. The scheme has been tested generating two wideband signals at 10GHz and 40GHz, and controlling their independent delays at two antenna elements. Thanks to the multiple functionalities, the proposed scheme allows to improve the effectiveness of the photonic approach, reducing its cost and allowing flexibility, extremely wide bandwidth, and high stability. PMID:24104176

Ghelfi, Paolo; Laghezza, Francesco; Scotti, Filippo; Serafino, Giovanni; Pinna, Sergio; Bogoni, Antonella

2013-09-23

117

Method on echoed signal denoising of bathymetric sounding laser radar  

NASA Astrophysics Data System (ADS)

As the ladar bathymetry is affected by many factors, its echoed signal contains a lot kinds of noises. There are the interference noise of laser, the clutter noise, the water-reflected noise, the underwater scattered noise, the electric noise and the synoptic disturbance noise after analyzing the echoed signal. Consequently, how to remove noise from the signal and how to accurately extract the useful distance information has the direct bearing on the effect of the ladar bathymetry. On the basis of kinds of noises and the features of the noises, this paper puts forward a echoed signal de-noising method by the way of wavelet decomposition and threshold processing. To begin with, it introduces some kinds of noise. Then, it talks over how to treat with the echoed signal according to the heterogeneities of the signal and the noise. The processing of echoed signal de-noising of ladar bathymetry makes it clear that this method can not only actively suppress the noise, but also effectively abstract the useful signal.

Cheng, Hua; Wang, Huachuang; Nie, Ruijie

2012-10-01

118

Brillouin precursor waveforms pertaining to UWB noise radar signals propagating through dispersive media  

NASA Astrophysics Data System (ADS)

The electromagnetic (EM) waves propagating through causal, linear, and lossy dispersive media (soil, foliage, plasma, water, biological tissue, etc.), experience frequency-dependent attenuation and phase distortion. This has assumed significant importance for systems operating with ultrawideband (UWB) spectrum. This paper analyzes the dynamical evolution of UWB noise radar signals through dispersive media. The effects on the signal propagation due to the evolution of the Brillouin precursor through dispersive media are discussed. The evolving waveforms are then compared with the Brillouin precursor due to rectangular sine-modulated deterministic signals. The advantages of random noise waveforms through dispersive media are also discussed.

Dawood, M.; Alejos, A. V.

2011-05-01

119

DURIP: Integrated Sensing and Computation for Passive Covert Radar, Signals Intelligence, and Other Applications Driven by Moore's Law.  

National Technical Information Service (NTIS)

Passive radar systems employing 'illuminators of opportunity' such as commercial television and FM radio signals instead of dedicated radar transmitters have been the subject of increasing interest over the past decade. Under the subject contract funds, c...

A. Lanterman D. V. Anderson

2005-01-01

120

Simulation and signal processing of through wall UWB radar for human being's periodic motions detection  

NASA Astrophysics Data System (ADS)

The human's Micro-Doppler signatures resulting from breathing, arm, foot and other periodic motion can provide valuable information about the structure of the moving parts and may be used for identification and classification purposes. In this paper, we carry out simulate with FDTD method and through wall experiment with UWB radar for human being's periodic motion detection. In addition, Advancements signal processing methods are presented to classify and to extract the human's periodic motion characteristic information, such as Micro-Doppler shift and motion frequency. Firstly, we apply the Principal Component Analysis (PCA) with singular value decomposition (SVD) to denoise and extract the human motion signal. Then, we present the results base on the Hilbert-Huang transform (HHT) and the S transform to classify and to identify the human's micro-Doppler shift characteristics. The results demonstrate that the combination of UWB radar and various processing methods has potential to detect human's Doppler signatures effectively.

Li, Jing; Liu, Fengshan; Xu, Penglong; Zeng, Zhaofa

2013-05-01

121

Characterization of wall dispersive and attenuative effects on UWB radar signals  

Microsoft Academic Search

This paper addresses the potentials of ultra-wideband (UWB) through-wall imaging radars compared with conventional narrowband systems. The challenges that limit the utilization of high precision UWB systems are examined with the aim of mitigating them. These challenges include multi-path, pulse dispersion, and antenna effects on the pulse shape due to angles of transmission and arrival. The propagation of UWB signals

Ali Muqaibel; Ahmad Safaai-Jazi

2008-01-01

122

High spectrum purity signal source applied in X-band radar frequency criterion generator  

Microsoft Academic Search

A high spectrum purity DDS-PLL signal source applied in X-band radar frequency criterion generator is introduced. It's specifications list the following: output frequency range 8500 MHz~9800 MHz; hopping step 1 kHz; hopping points 1,000,000; phase noise <-80 dBdHz@10 kHz. A novel and particular scheme is introduced, a good many mutual inconsistent factors can be satisfied simultaneously by using this method,

Yang Yumei; Zhang Yuxin; Zhou Zheng'ou

2001-01-01

123

Model-Based Information Extraction From Synthetic Aperture Radar Signals  

NASA Astrophysics Data System (ADS)

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

Matzner, Shari A.

124

Wind-speed inversion from HF radar first-order backscatter signal  

NASA Astrophysics Data System (ADS)

Land-based high-frequency (HF) radars have the unique capability of continuously monitoring ocean surface environments at ranges up to 200 km off the coast. They provide reliable data on ocean surface currents and under slightly stricter conditions can also give information on ocean waves. Although extraction of wind direction is possible, estimation of wind speed poses a challenge. Existing methods estimate wind speed indirectly from the radar derived ocean wave spectrum, which is estimated from the second-order sidebands of the radar Doppler spectrum. The latter is extracted at shorter ranges compared with the first-order signal, thus limiting the method to short distances. Given this limitation, we explore the possibility of deriving wind speed from radar first-order backscatter signal. Two new methods are developed and presented that explore the relationship between wind speed and wave generation at the Bragg frequency matching that of the radar. One of the methods utilizes the absolute energy level of the radar first-order peaks while the second method uses the directional spreading of the wind generated waves at the Bragg frequency. For both methods, artificial neural network analysis is performed to derive the interdependence of the relevant parameters with wind speed. The first method is suitable for application only at single locations where in situ data are available and the network has been trained for while the second method can also be used outside of the training location on any point within the radar coverage area. Both methods require two or more radar sites and information on the radio beam direction. The methods are verified with data collected in Fedje, Norway, and the Ligurian Sea, Italy using beam forming HF WEllen RAdar (WERA) systems operated at 27.68 and 12.5 MHz, respectively. The results show that application of either method requires wind speeds above a minimum value (lower limit). This limit is radar frequency dependent and is 2.5 and 4.0 m/s for 27.68 and 12.5 MHz, respectively. In addition, an upper limit is identified which is caused by wave energy saturation at the Bragg wave frequency. Estimation of this limit took place through an evaluation of a year long database of ocean spectra generated by a numerical model (third generation WAM). It was found to be at 9.0 and 11.0 m/s for 27.68 and 12.5 MHz, respectively. Above this saturation limit, conventional second-order methods have to be applied, which at this range of wind speed no longer suffer from low signal-to-noise ratios. For use in operational systems, a hybrid of first- and second-order methods is recommended.

Shen, Wei; Gurgel, Klaus-Werner; Voulgaris, George; Schlick, Thomas; Stammer, Detlef

2012-01-01

125

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

126

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

127

Space-time reduced rank methods and CFAR signal detection algorithms with applications to HPRF radar  

NASA Astrophysics Data System (ADS)

In radar applications, the statistical properties (covariance matrix) of the interference are typically unknown a priori and are estimated from a dataset with limited sample support. Often, the limited sample support leads to numerically ill-conditioned radar detectors. Under such circumstances, classical interference cancellation methods such as sample matrix inversion (SMI) do not perform satisfactorily. In these cases, innovative reduced-rank space-time adaptive processing (STAP) techniques outperform full-rank techniques. The high pulse repetition frequency (HPRF) radar problem is analyzed and it is shown that it is in the class of adaptive radar with limited sample support. Reduced-rank methods are studied for the HPRF radar problem. In particular, the method known as diagonally loaded covariance matrix SMI (L-SMI) is closely investigated. Diagonal loading improves the numerical conditioning of the estimated covariance matrix, and hence, is well suited to be applied in a limited sample support environment. The performance of L-SMI is obtained through a theoretical distribution of the output conditioned signal-to-noise ratio of the space-time array. Reduced-rank techniques are extended to constant false alarm rate (CFAR) detectors based on the generalized likelihood ratio test (GLRT). Two new modified CFAR GLRT detectors are considered and analyzed. The first is a subspace-based GLRT detector where subspace-based transformations are applied to the data prior to detection. A subspace transformation adds statistical stability which tends to improve performance at the expense of an additional SNR loss. The second detector is a modified GLRT detector that incorporates a diagonally loaded covariance matrix. Both detectors show improved performance over the traditional GLRT.

Ayoub, Tareq Fawzi

128

Knowledge-Based Radar Signal and Data Processing (Le traitement du signal et des donnees radar base sur les connaissances) (CD-ROM).  

National Technical Information Service (NTIS)

Radar systems are an important component of NATO military operations. In response to increasingly severe threats from military targets with reduced radar cross sections, slow moving and low flying targets, targets hidden in foliage and under trees, and in...

2005-01-01

129

Performance analysis of the weighted window CFAR algorithms [radar signal processing  

Microsoft Academic Search

With the deterioration of radar operation environment and the enhancement of menace to radar, the task of radar target detection becomes more complicated. Such as the detection of airplane, ship or cruise missile in over the horizon radar (OTHR), and the detection of moving targets in synthetic aperture radar (SAR). Therefore, it is necessary to make a further study of

Meng Xiangwei; Guan Jian; He You

2003-01-01

130

Digital signal processing and numerical analysis for radar in geophysical applications  

NASA Astrophysics Data System (ADS)

Numerical solutions for signal processing are described in this work as a contribution to study of echo detection methods for ionospheric sounder design. The ionospheric sounder is a high frequency radar for geophysical applications. The main detection approach has been done by implementing the spread-spectrum techniques using coding methods to improve the radar's range resolution by transmitting low power. Digital signal processing has been performed and the numerical methods were checked. An algorithm was proposed and its computational complexity was calculated.The proposed detection process combines two channels correlations with the local code and calculates threshold (Vt) by statistical evaluation of the background noise to design a detection algorithm. The noisy signals treatment was performed depending on the threshold and echo amplitude. In each case, the detection was improved by using coherent integration. Synthetic signals, close loop and actual echoes, obtained from the Advanced Ionospheric Sounder (AIS-INGV) at Rome Ionospheric Observatory, were used to verify the process.The results showed that, even in highly noisy environments, the echo detection is possible.Given that these are preliminary results, further studies considering data sets corresponding to other geophysical conditions are needed.

Molina, María G.; Cabrera, M. A.; Ezquer, R. G.; Fernandez, P. M.; Zuccheretti, E.

2013-05-01

131

Large dynamic range time-frequency signal analysis with application to helicopter Doppler radar data  

NASA Astrophysics Data System (ADS)

Despite the enhanced time-frequency analysis (TFA) detailing capability of quadratic TFAs like the Wigner and Cohen representations, their performance with signals of large dynamic range (DNR in excess of 40 dB) is not acceptable due to the inability to totally suppress the cross-term artifacts which typically are much stronger than the weakest signal components that they obscure. AMTI and GMTI radar targets exhibit such high dynamic range when microDoppler is present, with the aspects of interest being the weakest components. This paper presents one of two modifications of linear TFA to provide the enhanced detailing behavior of quadratic TFAs without introducing cross terms, making it possible to see the time-frequency detail of extremely weak signal components. The technique described here is based on subspace-enhanced linear predictive extrapolation of the data within each analysis window to create a longer data sequence for conventional STFT TFA. The other technique, based on formation of a special two-dimensional transformed data matrix analyzed by high-definition two-dimensional spectral analysis methods such as 2-D AR or 2-D minimum variance, is compared to the new technique using actual AMTI and GMTI radar data.

Marple, Stanley L., Jr.; Marino, Claudio S.; Strange, Shawn

2003-12-01

132

An overview of an illuminator of opportunity passive radar research project and its signal processing research directions  

Microsoft Academic Search

In this paper, an overview of an Illuminator Of Opportunity (IOO) passive radar research project being conducted at DSTO is presented, with a specific focus on the signal processing research directions that are being investigated. The overview provides a discussion on the selection of transmitters as well as a description of the multi-channel receiver. The signal processing research direction discussion

J. Palmer; S. Palumbo; A. Summers; D. Merrett; S. Searle; S. Howard

2011-01-01

133

Evaluation of the Interferences of GNSS (Galileo\\/GPS) signals on Air Traffic Control Radar and Wind Profiler Radar  

Microsoft Academic Search

GNSS systems use frequency band close to that of L-band primary surveillance radar for Air Traffic Contro, i.e. 1250-1350 MHz, and of some Wind Profiler Radar (1290 MHz). According to the World Radio Communication Conference 2003 (WRC-03) resolution, in order to protect Aeronautic Radio Navigation System (ARNS) systems, Radio Navigation Satellite System (RNSS) administrations shall ensure that the equivalent power

G. Galati; M. Leonardi; C. Cosenza; F. Lo Zito; F. Gottifredi

2006-01-01

134

Nanoelectrospray Emitter Arrays Providing Inter-Emitter Electric Field Uniformity  

PubMed Central

Arrays of electrospray ionization (ESI) emitters have been reported previously as a means of enhancing ionization efficiency or signal intensity. A key challenge when working with multiple, closely spaced ESI emitters is overcoming the deleterious effects caused by electrical interference among neighboring emitters. Individual emitters can experience different electric fields depending on their relative position in the array, such that it becomes difficult to operate all of the emitters optimally for a given applied potential. In this work, we have developed multi-nanoESI emitters arranged with a circular pattern, which enable the constituent emitters to experience a uniform electric field. The performance of the circular emitter array was compared to a single emitter and to a previously developed linear emitter array, which verified that improved electric field uniformity was achieved with the circular arrangement. The circular arrays were also interfaced with a mass spectrometer via a matching multi-capillary inlet, and the results were compared with those obtained using a single emitter. By minimizing inter-emitter electric field inhomogeneities, much larger arrays having closer emitter spacing should be feasible.

Kelly, Ryan T.; Page, Jason S.; Marginean, Ioan; Tang, Keqi; Smith, Richard D.

2008-01-01

135

The detection of weak signal patterns in radar ocean intensity images  

SciTech Connect

Detection of weak patterns in radar ocean RCS images is complicated by the fact that signals and noise are interactive rather than additive and the ambient noise background is non Gaussian or even strongly non Gaussian at low grazing angles. This paper addresses this difficult problem with the aid of two simplifying assumptions: (1) the signal modulation is weak, and (2) departure from Gaussianity is small. In situations where this departure is large, an approach is suggested for reducing this non Gaussianity. The relevant weak signal detection theory, based on the Likelihood ratio, is reviewed and adapted for use in the analysis. The approach to this problem, similar to that previously used for complex images, is facilitated by approximating the multivariate probability distributions as a composite integral involving underlying processes which are assumed to be Gaussian. This formulation, subject to the approximations in the analysis, permits derivation of an ideal detection statistic (which determines the form of optimum receiver) and a signal/noise ratio which characterizes detection performance in the weak signal limit. Implications for image processing are discussed and directions for future analysis are suggested.

Manasse, R.

1996-06-15

136

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

137

Radar observables  

NASA Astrophysics Data System (ADS)

A comprehensive account is given of missile design considerations relevant to the prediction, control, and measurement of airframe radar cross sections (RCSs), with a view to the minimization of missile observability. RCS reduction may proceed through airframe shaping to deflect incident radar emissions, as well as through the use of radar-absorbing surface materials and the devision of active radar signal-cancellation methods; some combination of these is often required, due to the deficiencies of any one method. The interaction of all RCS-reduction methods with airframe aerodynamic-design criteria are stressed.

Knott, Eugene F.

138

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

NASA Astrophysics Data System (ADS)

MIMO radar utilizes the transmission and reflection of multiple independent waveforms to construct an image approximating a target scene. Compressed sensing (CS) techniques such as total variation (TV) minimization and greedy algorithms can permit accurate reconstructions of the target scenes from undersampled data. The success of these CS techniques is largely dependent on the structure of the measurement matrix. A discretized inverse scattering model is used to examine the imaging problem, and in this context the measurement matrix consists of array parameters regarding the geometry of the transmitting and receiving arrays, signal type, and sampling rate. We derive some conditions on these parameters that guarantee the success of these CS reconstruction algorithms. The effect of scene sparsity on reconstruction accuracy is also addressed. Numerical simulations illustrate the success of reconstruction when the array and sampling conditions are satisfied, and we also illustrate erroneous reconstructions when the conditions are not satisfied.

Lopez, Juan; Qiao, Zhijun

2013-05-01

139

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

140

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

141

Radar Ionospheric Impact Mitigation  

Microsoft Academic Search

New ionospheric modeling technology is being developed to improve correction of ionospheric impacts on the performance of ground-based space-surveillance radars (SSRs) in near-real-time. These radars, which detect and track space objects, can experience significant target location errors due to ionospheric delay and refraction of the radar signals. Since these radars must detect and track targets essentially to the radar horizon,

G. Bishop; D. Decker; C. Baker

2006-01-01

142

A HWIL test facility of infrared imaging laser radar using direct signal injection  

Microsoft Academic Search

Laser radar has been widely used these years and the hardware-in-the-loop (HWIL) testing of laser radar become important because of its low cost and high fidelity compare with On-the-Fly testing and whole digital simulation separately. Scene generation and projection two key technologies of hardware-in-the-loop testing of laser radar and is a complicated problem because the 3D images result from time

Qian Wang; Wei Lu; Chunhui Wang; Qi Wang

2005-01-01

143

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

2012-05-01

144

Statistical MIMO Radar.  

National Technical Information Service (NTIS)

Inspired by recent advances in multiple-input multiple-output (MIMO) communications, we introduce the statistical MIMO radar concept. Unlike beamforming, array radar, or STAP, which presuppose a high correlation between signals either transmitted or recei...

A. Haimovich E. Fishler R. Blum D. Chizhik R. Valenzuela

2004-01-01

145

Using the inverse Chirp-Z transform for time-domain analysis of simulated radar signals  

Microsoft Academic Search

There exists a need to develop a method to locate underground voids, or caches. In the past, ground penetrating radar (GPR) operating in the time domain mode has been used. In this paper, we turn our attention to stepped frequency radar, capable of making frequency domain reflection coefficient measurements. We then apply the inverse Chirp-Z transform (ICZT) to this data,

Frickey

1995-01-01

146

FPGA-based Radar Signal Processing for Automotive Driver Assistance System  

Microsoft Academic Search

Safety and comfort applications are addressed using driver assistance (DA) systems like adaptive cruise control (ACC) system using long range radar (LRR) or short range radar (SRR) or both. Novel waveforms and functionalities applied to next generation DA multi-sensor systems and their corresponding complex algorithms require advanced digital hardware supporting high computation rate and severe real-time constraints. In this paper,

Jean Saad; Amer Baghdadi; Frantz Bodereau

2009-01-01

147

Multi-PRI Signal Processing for the Terminal Doppler Weather Radar. Part II: Range–Velocity Ambiguity Mitigation  

Microsoft Academic Search

Multiple pulse-repetition interval (multi-PRI) transmission is part of an adaptive signal transmission and processing algorithm being developed to combat range-velocity (RV) ambiguity for the Terminal Doppler Weather Radar (TDWR). In Part I of this two-part paper, an adaptive clutter filtering procedure that yields low biases in the moments estimates was presented. In this part, algorithms for simultaneously providing range-overlay protection

John Y. N. Cho

2005-01-01

148

Applications of time-frequency and time-scale transforms to ultra-wideband radar transient signal detection  

NASA Astrophysics Data System (ADS)

In this paper we use a non-stationary approach and analyze ultra-wideband (UWB) radar data using time-frequency and time-scale transformations. The time-frequency transformations considered are the Short-Time Fourier Transform (STFT), the Wigner-Ville Distribution (WD), the Instantaneous Power Spectrum (IPS), and the ZAM transform. Two discrete implementations of the Wavelet Transform (DWT) are also investigated: the decimated A- trous algorithm proposed by Holschneider et al, which uses non-orthogonal wavelets; and the Mallat algorithm, which employs orthogonal wavelets. The transients under study are UWB radar returns from a boat (with and without corner reflector) in the presence of sea clutter, multipath, and radio frequency interferences (RFI). Results show that all time-frequency and time-scale transforms clearly detect the transient radar returns corresponding to the boat with a corner reflector. However, as the radar cross section of the target decreases (boat without a corner reflector), results change drastically as the RFI component dominates the signal. Simulations show that the Instantaneous Power Spectrum may be better adapted for localizing the transient among the time-frequency techniques studied. The decimated A-trous algorithm has the best time resolution of the techniques studied as the return appears better localized in the scalogram.

Fargues, Monique P.; Brooks, William A.

1993-11-01

149

Measurements and simulation of ionospheric scattering on VHF and UHF radar signals: Coherence times, coherence bandwidths, and S4  

NASA Astrophysics Data System (ADS)

Irregularities in the electron density of the ionosphere cause phase and amplitude scintillation on transionospheric VHF and UHF radar signals, particularly at lower radio frequencies. The design of radar and other transionospheric systems requires good estimates of the coherence bandwidth (CB) and coherence time (CT) imposed by a turbulent ionosphere. CB and CT measurements of the equatorial ionosphere, made using the Advanced Research Project Agency Long-range Tracking and Identification Radar 158 MHz and 422 MHz phase coherent radar located on Kwajalein (9.4°N, 167.5°E), are presented as a function of the two-way S4 scintillation index at 422 MHz The log linear regression equations are CT = 1.46 exp(-1.40 S4) s at 158 MHz and CT = 2.31 exp(-1.10 S4) s at 422 MHz. CT also varies by a factor of 2-3 depending on the effective scan velocity through the ionosphere, veff. The CT and CB, as a function of S4, have been compared to those from the Trans-Ionospheric Radio Propagation Simulator, a phase screen model. A close agreement is achieved using appropriate values of veff and midrange values of phase spectral index and outer scale. Validation of CB is, however, limited by insufficient radar chirp bandwidth. Formulating the model in terms of the two-way S4 index (an easily measurable parameter) rather than more fundamental phase screen parameters (which are difficult to obtain), improves its utility for the systems engineer. The frequency dependencies (spectral indices) of S4 and of CT are also presented to allow interpolation and some extrapolation of these results to other frequencies.

Rogers, Neil C.; Cannon, Paul S.; Groves, Keith M.

2009-02-01

150

A feature extraction method for the signal sorting of interleaved radar pulse serial  

Microsoft Academic Search

In this paper, a new feature extraction method for radar pulse sequences is presented based on structure function and empirical\\u000a mode decomposition. In this method, 2-D feature information was constituted by using radio frequency and time-of-arrival,\\u000a which analyzed the feature of radar pulse sequences for the very first time by employing structure function and empirical\\u000a mode decomposition. The experiment shows

Qiang Guo; Xingzhou Zhang; Zheng Li

2007-01-01

151

Space-time reduced rank methods and CFAR signal detection algorithms with applications to HPRF radar  

Microsoft Academic Search

In radar applications, the statistical properties (covariance matrix) of the interference are typically unknown a priori and are estimated from a dataset with limited sample support. Often, the limited sample support leads to numerically ill-conditioned radar detectors. Under such circumstances, classical interference cancellation methods such as sample matrix inversion (SMI) do not perform satisfactorily. In these cases, innovative reduced-rank space-time

Tareq Fawzi Ayoub

1998-01-01

152

UWB Radar: Mechanical Scanning and Signal Processing for Through-the-Wall Imaging  

NASA Astrophysics Data System (ADS)

This chapter presents a state of the art of the UWB (ultra-wideband) radar for through-the-wall imaging, followed by a description of different methods to scan a scene situated through a wall using a UWB system. Principal attention of this chapter focuses on a mechanical scanning radar system and associated image processing to detect a human body through a wall and also the environment of a target.

Liebe, C.; Gaugue, A.; Khamlichi, J.; Menard, M.; Ogier, J.-M.

153

Controlling radar signature  

SciTech Connect

Low observable technologies for military and tactical aircraft are reviewed including signature-reduction techniques and signal detection/jamming. Among the applications considered are low-signature sensors and the reduction of radar cross section in conjunction with radar-absorbing structures and materials. Technologies for reducing radar cross section are shown to present significant technological challenges, although they afford enhanced aircraft survivability.

Foulke, K.W. (U.S. Navy, Naval Air Warfare Center, China Lake, CA (United States))

1992-08-01

154

Doppler weather radar  

Microsoft Academic Search

The Doppler weather radar and its signals are examined from elementary considerations to show the origin and development of useful weather echo properties such as signal-to-noise ratio (SNR), range correlation, signal statistics, etc. We present a form of the weather radar equation which explicitly shows the echo power loss due to finite receiver bandwidth and how it is related to

RICHARD J. DOVIAK; DUSAN S. ZRNIC; DALE S. SIRMANS

1979-01-01

155

Advanced intermittent clutter filtering for radar wind profiler: signal separation through a Gabor frame expansion and its statistics  

NASA Astrophysics Data System (ADS)

A new signal processing method is presented for the suppression of intermittent clutter echoes in radar wind profilers. This clutter type is a significant problem during the seasonal bird migration and often results in large discrepancies between profiler wind measurements and independent reference data. The technique presented makes use of a discrete Gabor frame expansion of the coherently averaged time series data in combination with a statistical filtering approach to exploit the different signal characteristics between signal and clutter. The rationale of this algorithm is outlined and the mathematical methods used are presented in due detail. A first test using data obtained with an operational 482 MHz wind profiler indicates that the method outperforms the previously used clutter suppression algorithm.

Lehmann, V.; Teschke, G.

2008-05-01

156

An ambiguity-function-based method for analysis of Doppler decompressed radar signals applied to EISCAT measurements of oblique UHF-VHF meteor echoes  

Microsoft Academic Search

Binary phase modulation using Barker codes as the modulating sequences is often used as a pulse compression technique in incoherent scatter radar measurements of the ionospheric E region. Demodulation of the compressed signal is usually accomplished by matched filtering techniques. If the target has appreciable velocity, the resulting Doppler shift detunes the scattered signal relative to the filter, and the

G. Wannberg; A. Pellinen-Wannberg; A. Westman

1996-01-01

157

Using the inverse Chirp-Z transform for time-domain analysis of simulated radar signals  

SciTech Connect

There exists a need to develop a method to locate underground voids, or caches. In the past, ground penetrating radar (GPR) operating in the time domain mode has been used. In this paper, we turn our attention to stepped frequency radar, capable of making frequency domain reflection coefficient measurements. We then apply the inverse Chirp-Z transform (ICZT) to this data, generating a time domain response. The scenario under consideration is that of an airborne radar passing over the surface of the earth. The radar is directed toward the surface and is capable of measuring the reflection coefficient, seen looking toward the earth, as a function of frequency. The frequency domain -data in this work is simulated and is generated from a transmission line model of the problem. Using the ICZT we convert this frequency domain data to the time domain. Once in the time domain, reflections due to discontinuities appear at times indicating their relative distance from the source. The discontinuities occurring beyond the surface of the earth could be indicative of underground structures. The ICZT allows a person to zoom in on the time span of interest by specifying the starting time, the time resolution, and the number of time steps.

Frickey, D.A.

1995-01-01

158

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

Microsoft Academic Search

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

C. S. Kochiss; L. Liu

2004-01-01

159

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

160

Detection and Recognition of Target Signals in Radar Clutter via Adaptive CFAR Tests  

Microsoft Academic Search

In this paper, adaptive CFAR tests are described which allow one to classify radar clutter into one of several major categories, including bird, weather, and target classes. These tests do not require the arbitrary selection of priors as in the Bayesian classifier. The decision rule of the recognition techniques is in the form of associating the p-dimensional vector of observations

N. A. Nechval; K. N. Nechval; G. Berzinsh; M. Purgailis

2006-01-01

161

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

162

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

USGS Publications Warehouse

A method is derived for determining the dependence of radar backscatter on incidence angle that is applicable to the region corresponding to a particular radar image. The method is based on enforcing mathematical consistency between the frequency distribution of the image's pixel signals (histogram of DN values with suitable normalizations) and a one-dimensional frequency distribution of slope component, as might be obtained from a radar or laser altimetry profile in or near the area imaged. In order to achieve a unique solution, the auxiliary assumption is made that the two-dimensional frequency distribution of slope is isotropic. The backscatter is not derived in absolute units. The method is developed in such a way as to separate the reflectance function from the pixel-signal transfer characteristic. However, these two sources of variation are distinguishable only on the basis of a weak dependence on the azimuthal component of slope; therefore such an approach can be expected to be ill-conditioned unless the revision of the transfer characteristic is limited to the determination of an additive instrumental background level. The altimetry profile does not have to be registered in the image, and the statistical nature of the approach minimizes pixel noise effects and the effects of a disparity between the resolutions of the image and the altimetry profile, except in the wings of the distribution where low-number statistics preclude accuracy anyway. The problem of dealing with unknown slope components perpendicular to the profiling traverse, which besets the one-to-one comparison between individual slope components and pixel-signal values, disappears in the present approach. In order to test the resulting algorithm, an artificial radar image was generated from the digitized topographic map of the Lake Champlain West quadrangle in the Adirondack Mountains, U.S.A., using an arbitrarily selected reflectance function. From the same map, a one-dimensional frequency distribution of slope component was extracted. The algorithm recaptured the original reflectance function to the degree that, for the central 90% of the data, the discrepancy translates to a RMS slope error of 0.1 ???. For the central 99% of the data, the maximum error translates to 1 ???; at the absolute extremes of the data the error grows to 6 ???. ?? 1988 Kluwer Academic Publishers.

Wildey, R. L.

1988-01-01

163

Wind-speed inversion from HF radar first-order backscatter signal  

Microsoft Academic Search

Land-based high-frequency (HF) radars have the unique capability of continuously monitoring ocean surface environments at\\u000a ranges up to 200 km off the coast. They provide reliable data on ocean surface currents and under slightly stricter conditions\\u000a can also give information on ocean waves. Although extraction of wind direction is possible, estimation of wind speed poses\\u000a a challenge. Existing methods estimate wind

Wei Shen; Klaus-Werner Gurgel; George Voulgaris; Thomas Schlick; Detlef Stammer

164

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

Microsoft Academic Search

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

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

2008-01-01

165

Fiber-optic network architectures for on-board radar and avionics signal distribution  

Microsoft Academic Search

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. Recent advances in fiber optic technology, especially wavelength division multiplexing (WDM), have opened a number of possibilities for designing on-board fiber optic networks for radar and avionics RF

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

2000-01-01

166

Beam emittance measurements in RHIC  

SciTech Connect

The RHIC proton polarimeters can operate in scanning mode, giving polarization profiles and transverse beam intensity profile (beam emittance) measurements. The polarimeters function as wire scanners, providing a very good signal/noise ratio and high counting rate. This allows accurate bunch-by-bunch emittance measurements during fast target sweeps (<1 s) through the beam. Very thin carbon strip targets make these measurements practically non-destructive. Bunch by bunch emittance measurements are a powerful tool for machine set-up; in RHIC, individual proton beam transverse emittances can only be measured by CNI polarimeter scans. We discuss the consistency of these measurements with Ionization Profile Monitors (IPMs) and vernier scan luminosity measurements. Absolute accuracy limitations and cross-calibration of different techniques are also discussed.

Zelenski,A.; Bazilevsky, A.; Bunce, G.; Gill, R.; Huang, H.; Makdisi, Y.; Morozov, B.; Nemesure, S.; Russo, t.; Steski, D.; Sivertz, M.

2009-05-04

167

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.; Strifors, H.C. [National Defense Research Establishment, Stockholm (Sweden)

1996-09-01

168

Passive coherent location radar demonstration  

Microsoft Academic Search

This paper describes a passive coherent location (PCL) radar system developed by Dynetics, Inc. This system uses commercial FM broadcast signals for the radar waveform. This paper presents a technical description of the system and performance data.

C. L. Zoeller; M. J. Moody

2002-01-01

169

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

170

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

171

Wavelet-based progressive classification with learning: applications to radar signals  

NASA Astrophysics Data System (ADS)

In this paper we investigate the problem of fast and accurate classification of naval targets from radar returns. The algorithms can be applied to both 1-D and 2-D data (i.e., high range resolution and imaging radar returns). We describe the structure of these algorithms and report experimental results on their performance with synthetic returns from ships. We have successfully addressed the problem of reducing the target model representations with respect to viewpoint variations and other sensor parametric variations. Our method can be viewed as a quantization of the space of sensing operations. The resulting multiresolution aspect graph is a (relational) graph representation of this quantization. Aspect graphs of target radar returns are generated algorithmically. Since our off-line model/parameter tuning methods are based on general vector quantization, our methods extend naturally and efficiently to multi-sensor data: LADAR, TV, mmWave, SAR, etc. We describe new results on the `continuity' of the aspect graph, new properties and improvements of our algorithmic constructions. Our basic classification algorithm utilizes a cascade of a wavelet preprocessor followed by a tree- structured clustering algorithm; a learning mode can also be added. We develop a high performance parallel progressive classification algorithm and report on its performance and complexity. We show experiments illustrating that the parallel algorithm outperforms a compound version (which is the more intuitive choice) and that it has performance close to Bayes optimal classification (via comparison to learning vector quantization). We outline an analytical framework for establishing these results theoretically. We also discuss similar experiments from face recognition and medical image classification problems.

Baras, John S.; Wolk, Sheldon I.

1995-04-01

172

Scalable Microstructured Photoconductive Terahertz Emitters  

NASA Astrophysics Data System (ADS)

The development of scalable emitters for pulsed broadband terahertz (THz) radiation is reviewed. Their large active area in the 1 - 100 mm2 range allows for using the full power of state-of-the-art femtosecond lasers for excitation of charge carriers. Large fields for acceleration of the photogenerated carriers are achieved at moderate voltages by interdigitated electrodes. This results in efficient emission of single-cycle THz waves. THz field amplitudes in the range of 300 V/cm and 17 kV/cm are reached for excitation with 10 nJ pulses from Ti:sapphire oscillators and for excitation with 5 ?J pulses from amplified lasers, respectively. The corresponding efficiencies for conversion of near-infrared to THz radiation are 2.5 × 10-4 (oscillator excitation) and 2 × 10-3 (amplifier excitation). In this article the principle of operation of scalable emitters is explained and different technical realizations are described. We demonstrate that the scalable concept provides freedom for designing optimized antenna patterns for different polarization modes. In particular emitters for linearly, radially and azimuthally polarized radiation are discussed. The success story of photoconductive THz emitters is closely linked to the development of mode-locked Ti:sapphire lasers. GaAs is an ideal photoconductive material for THz emitters excited with Ti:sapphire lasers, which are widely used in research laboratories. For many applications, especially in industrial environments, however, fiber-based lasers are strongly preferred due to their lower cost, compactness and extremely stable operation. Designing photoconductive emitters on InGaAs materials, which have a low enough energy gap for excitation with fiber lasers, is challenging due to the electrical properties of the materials. We discuss why the challenges are even larger for microstructured THz emitters as compared to conventional photoconductive antennas and present first results of emitters suitable for excitation with ytterbium-based fiber lasers. Furthermore an alternative concept, namely the lateral photo-Dember emitter, is presented. Due to the strong THz output scalable emitters are well suited for THz systems with fast data acquisition. Here the application of scalable emitters in THz spectrometers without mechanical delay stages, providing THz spectra with 1 GHz spectral resolution and a signal-to-noise ratio of 37 dB within 1 s, is presented. Finally a few highlight experiments with radiation from scalable THz emitters are reviewed. This includes a brief discussion of near-field microscopy experiments as well as an overview over gain studies of quantum-cascade lasers.

Winnerl, Stephan

2011-12-01

173

Noncoherent integration of HRR RADAR signals for detection of fluctuating targets in non Gaussian clutter using the hough transform  

Microsoft Academic Search

In a HRR RADAR where the size of target is larger than wavelength of the RADAR and RADAR range resolution cells, and target returns from different scattering centres of the target produce different patterns in successive scans, make application of traditional methods of clutter suppression inefficient. In this paper, we propose another approach for noncoherent integration of HRR pulses based

Fariba Haghjoo; A. R. Mallahzadeh; Vahid Riazi; A. S Heikhi

2011-01-01

174

Intentional emitters above 2400 MHz: how best to measure the transmitted signal level for FCC Part 15 compliance  

Microsoft Academic Search

This paper investigates the commonly used methods for measurement of the intentional signal levels emitted by Part 15 radio frequency (RF) devices operating above 2400 MHz, and that have built-in antennas that are soldered directly to a printed circuit (PC) board and are not normally removable. In this paper, we look at what the Federal Communication Commission (FCC) rules really

Edwin L. Bronaugh

2000-01-01

175

Processing of wide-angle synthetic aperture radar signals for target detection  

NASA Astrophysics Data System (ADS)

This study investigated methods of targets detection using Wide-Angle Synthetic Aperture Radar (WASAR). WASAR uses multiple aspect angle Synthetic Aperture Radar (SAR) images of the same scene. The SAR images were generated using a pre-release software package from package from Loral Corporation. The software was able to generate 512 by 512 pixel SAR images that contained various vegetation return which for our purposes we classified as clutter. Within this clutter, targets (M35 trucks) could be placed at random location and orientations. The software also had the capability of generating fully-polarimetic WASAR images with multiple depression angles. This data was then processed and various detection algorithms tested to exploit the amount and diversity of information available from the multiple images. SAR images are generally known to contain large amounts of data, and WASAR images contain even more due to the multiple images. Various pre-processing filters were analyzed for detection optimization. These filters included: polarimetric averaging, polarimetric span, polarimetric optimal weighting, and polarimetric whitening filters. Simple classical detection (thresholding) algorithms were evaluated using these preprocessed data sets. The use of WASAR imagery improved detection by allowing thresholds to be set higher than for simple SAR thereby avoiding false alarms yet still allowing detection of the known targets.

Knurr, Kurt W.

1993-12-01

176

Measurements and simulation of ionospheric scattering on VHF and UHF radar signals: Channel scattering function  

NASA Astrophysics Data System (ADS)

The design and operation of transionospheric VHF and UHF radars requires knowledge of amplitude and phase scintillation due to ionospheric scattering. Phase coherence is of particular importance where long coherent integration periods and large bandwidths are required. A thin phase screen, parabolic equation based, Trans-Ionospheric Radio Propagation Simulator (TIRPS) is described. Modeled channel scattering functions (CSFs) are compared to experimental VHF and UHF data derived from the Advanced Research Projects Agency Long-range Tracking and Instrumentation Radar on Kwajalein Island (9.4°N, 166.8°E). TIRPS quantitatively reproduces the experimental results, including the quasi-parabolic profile observed in the measured CSFs under strong turbulence conditions. Variations in the simulated CSF with ionospheric phase screen parameters are also presented. Under conditions of high integrated strength of turbulence (CkL), a low phase spectral index (p = 1), indicating relatively dense small-scale irregularities, produces pronounced range spreading. Conversely, when the spectral index is high (p = 4), indicative of strong focusing/defocusing by large-scale irregularities, there is increased Doppler spreading and, when the outer scale of irregularities is large, a greater likelihood of asymmetry of the CSF about the zero Doppler axis.

Rogers, Neil C.; Cannon, Paul S.; Groves, Keith M.

2009-02-01

177

Tracking Radar Advanced Signal Processing and Computing for Kwajalein Atoll (KA) Application.  

National Technical Information Service (NTIS)

Two means are examined whereby the operations of KMR during mission execution may be improved through the introduction of advanced signal processing techniques. In the first approach, the addition of real time coherent signal processing technology to the ...

S. D. Cottrill

1992-01-01

178

A digital signal processor for Doppler radar sensing of vital signs  

Microsoft Academic Search

A voltage waveform signal containing respiration and heartbeat signatures is low-pass filtered (0.7 Hz) for the respiration and band-pass filtered (1.0-3.0 Hz) for the heart signal. The autocorrelation function is used to calculate the rate per minute for each of these signals. To make the processor more robust, several signal processing techniques are applied. One of these techniques, a method

B. Lohman; O. Boric-Lubecke; V. M. Lubecke; P. W. Ong; M. M. Sondhi

2001-01-01

179

Millimeter radar  

Microsoft Academic Search

The paper discusses some of the advantages offered by millimeter waves over microwaves, reviews possible and past millimeter radar applications, and looks at some future millimeter radar systems. The coming millimeter radars include radiometric seekers, radiometers, and high resolution radar for satellite identification. Important problems to be resolved before millimeter radars can be put into production include component capability; radar

S. L. Johnston

1977-01-01

180

On peculiarities of scattering of microwave radar signals by breaking gravity-capillary waves  

NASA Astrophysics Data System (ADS)

We performed laboratory experiments to study peculiarities of radar scattering of microwave radiation by strongly nonlinear (breaking) gravity-capillary waves on the water surface. It was shown that the scattering from strongly nonlinear waves within the centimeter and, partially, decimeter wavelength range is due to the effects of their "micro-breaking" and the bound (spurious) capillary ripples excited on their profile. The phase velocity of the ripples coincides with the phase velocity of the generating waves. The scattering by meter waves, which at high amplitudes are characterized by strong breaking with tipping of the crest, is determined mainly by the quasi-linear capillary ripples, whose phase velocity is determined by the dispersion relation for free surface waves. In the case of the waves within an intermediate range, which have lengths from several decimeters to one meter, both the spurious and free capillary ripples contribute to the scattering.

Ermakov, S. A.; Kapustin, I. A.; Sergievskaya, I. A.

2012-12-01

181

Microphysical cross validation of spaceborne radar and ground polarimetric radar  

Microsoft Academic Search

Ground-based polarimetric radar observations along the beam path of the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), matched in resolution volume and aligned to PR measurements, are used to estimate the parameters of a gamma raindrop size distribution (RSD) model along the radar beam in the presence of rain. The PR operates at 13.8 GHz, and its signal returns

V. Chandrasekar; Steven M. Bolen; Eugenio Gorgucci

2003-01-01

182

Denoising of radar signals by using wavelets and Doppler estimation by S-Transform  

NASA Astrophysics Data System (ADS)

The s-transform is a variable window of STFT and extension of wavelet. This paper discussed the principle and method of Wavelet De-noising, reduced noise of pulse signal based on wavelet. It is shown that wavelet de-noising can eliminate most noise, and preserve effectively sudden change of signal. This paper analyzed and compared the effect of denoising of pulse signal in different ways all study shows de-noising of pulse signal based on wavelet have practical value.From the s-transform the Doppler frequency can be estimated in different ways.

Reddy, V. Siva Sankara; Rao, D. Thirumala

2012-08-01

183

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

184

Information retrieval and cross-correlation function analysis of random noise radar signal through dispersive media  

NASA Astrophysics Data System (ADS)

In this contribution we examine the propagation of an ultrawideband (UWB) random noise signal through dispersive media such as soil, vegetation, and water, using Fourier-based analysis. For such media, the propagated signal undergoes medium-specific impairments which degrade the received signal in a different way than the non-dispersive propagation media. Theoretically, larger penetration depths into a dispersive medium can be achieved by identifying and detecting the precursors, thereby offering significantly better signal-to-noise ratio and enhanced imaging. For a random noise signal, well defined precursors in term of peak-amplitude don't occur. The phenomenon must therefore be studied in terms of energy evolution. Additionally, the distortion undergone by the UWB random noise signal through a dispersive medium can introduce frequency-dependent uncertainty or noise in the received signal. This leads to larger degradation of the cross-correlation function (CCF), mainly in terms of sidelobe levels and main peak deformation, and consequently making the information retrieval difficult. We would further analyze one method to restore the shape and carrier frequency of the input UWB random noise signal, thereby, improving the CCF estimation.

Alejos, Ana Vazques; Dawood, Muhammad

2012-05-01

185

Pulse-Doppler UWB Radar  

Microsoft Academic Search

The paper contains measurement results of moving targets by pulse-Doppler UWB radar. The description of a radar, principle of operation and technical specification are presented. Conditions and results of measurements are described. Feature of the presented measurements: Doppler signals of linear moving targets whose linear sizes exceed resolution of radar

A. Chernenko; E. Ziganshin

2006-01-01

186

Ultrawideband radars: Features and capabilities  

Microsoft Academic Search

Features of ultrawideband (UWB) radars, which radiate signals whose spatial duration is substantially smaller than the antenna\\u000a dimensions and\\/or the longitudinal dimension of the illuminated target, are analyzed. It is shown that, during the radar observation\\u000a of the target, this signal changes its shape several times and enters the radar receiver as an unknown signal. In many cases,\\u000a this circumstance

I. Ya. Immoreev

2009-01-01

187

Penetration depth of interferometric synthetic-aperture radar signals in snow and ice  

NASA Astrophysics Data System (ADS)

Digital elevation models of glaciated terrain produced by the NASA/Jet Propulsion Laboratory (JPL) airborne interferometric synthetic-aperture radar (InSAR) instrument in Greenland and Alaska at the C- (5.6 cm wavelength) and L-band (24-cm) frequencies were compared with surface elevation measured from airborne laser altimetry to estimate the phase center of the interferometric depth, or penetration depth, ?p. On cold polar firn at Greenland summit, ?p = 9±2m at C- and 14±4m at L-band. On the exposed ice surface of Jakobshavn Isbrae, west Greenland, ?p = 1±2 m at C- and 3±3 m at L-band except on smooth, marginal ice where ?p=15±5 m. On colder marginal ice of northeast Greenland, ?p reaches 60 to 120 m at L-band. On the temperate ice of Brady Glacier, Alaska, ?p is 4±2 m at C-and 12±6 m at L-band, with little dependence on snow/ice conditions. The implications of the results on the scientific use of InSAR data over snow/ice terrain is discussed.

Rignot, Eric; Echelmeyer, Keith; Krabill, William

188

Circular array radar technical and applications  

NASA Astrophysics Data System (ADS)

A new type circular array radar is introduced in this paper. First, the working theory of this radar is introduced, as well as the signal processing method. The characteristics and advancements of this type of radar are detailed analyzed, and the key technology of the circular array radar is proposed. Second, two applications of circular array radar are introduced; they are VHF circular array long-range surveillance radar and L band mini circular array radar. Finally, the potential prospect of this circular array radar is proposed.

Xu, Chengfa; Wang, Chonghui; Hong, Yongbin

2013-03-01

189

Doppler Signal Processing and Instrumentation for Modified 'Porcupine' C-Band Pulse Doppler Radar.  

National Technical Information Service (NTIS)

Section 1 of the report summarizes doppler signal processing techniques in the following areas: Fast fourier transform processing; 'Pulse pair' processing; Doppler separation using a hilbert transformer. Section 2 of the report summarizes the following in...

F. E. Compton H. L. Groginsky R. B. Campbell V. Friedmann

1971-01-01

190

DDS-driven PLL frequency synthesizer for X-band radar signal simulation  

Microsoft Academic Search

A DDS-driven PLL frequency synthesizer architecture is given in this paper. The AD9854 DDS device is used to generate low frequency reference signal and to drive the PLL and VCO to generate RF signal. Experiments and measurement results showed that this frequency synthesizer had wider bandwidth and low phase noise level, and can be used to generate X-band continuous wave

Longjun Zhai; Yonghua Jiang; Xiang Ling; Weilang Gao

2006-01-01

191

Passive Radar using Multiple GSM Transmitting Stations  

Microsoft Academic Search

The atmosphere has a wide range of transmissions available from various sources like TV transmissions, GSM signals, FM Radio, AM Radio, GPS signals, etc. These signals open up the opportunity of designing different types of passive radars. Passive radar using a single GSM transmitting station have been designed, but this type of radar cannot give accurate target parameters. This paper

U. M. D. Mendi; B. K. Sarkar

2006-01-01

192

Phase retrieval techniques for radar ambiguity problems  

Microsoft Academic Search

The radar ambiguity function plays a central role in the theory of radar signals. Its absolute value (¦A(u)¦) measures the correlation between the signal u emitted by the radar transmitter and its echo after reaching a moving target. It is important to know signals that give rise to ambiguity functions of given shapes. Therefore, it is also important to know

Philippe Jaming

1999-01-01

193

Radar absorbing materials used for target camouflage  

Microsoft Academic Search

As a result of the developments within signal processing, transmitters and receivers areas radar technology has improved steadily over the past 50 years gaining in the sensor sensitivity, miniaturisation, power consumption, etc which allow to build smaller, more reliable and user friendly radar sensors. The effectiveness of these radar sensors is sufficiently threatening to merit the reduction of radar signature

I. NICOLAESCU

2006-01-01

194

Cognitive radar: a way of the future  

Microsoft Academic Search

This article discusses a new idea called cognitive radar. Three ingredients are basic to the constitution of cognitive radar: 1) intelligent signal processing, which builds on learning through interactions of the radar with the surrounding environment; 2) feedback from the receiver to the transmitter, which is a facilitator of intelligence; and 3) preservation of the information content of radar returns,

Simon Haykin

2006-01-01

195

Radar Techniques Program.  

National Technical Information Service (NTIS)

This is the fifth Quarterly Technical Summary covering the development of an airborne Multiple-Antenna Moving-Target Surveillance Radar (MASR) which employs special antenna and signal-processing techniques to provide continuous, wide-area surveillance of ...

C. E. Muehe

1974-01-01

196

Research of deformation of the fine phase structure of ultra wideband radar signals when passing through the system of identical selective filters  

Microsoft Academic Search

There has been found the exact solution to the response of the system of selective filters to a noise-like ultra wideband radar signal. The expressions were found for two forms of the enveloping curves of certain discretes of a pseudorandom sequence with phase-shift keying, i.e. the square and sinus-quadratic ones. In order to get the solutions with the accuracy up

I. D. Zolotaryov; Ya. E. Miller; T. O. Pozharsky

2005-01-01

197

Systematic Phase Codes for Resolving Range Overlaid Signals in a Doppler Weather Radar  

Microsoft Academic Search

This paper deals with the recovery of Doppler velocities in the presence of range overlaid echoes. Transmitted pulses are phase shifted to tag the echoes from scatterers, which are separated by the unambiguous range. A new systematic phase code and an algorithm for estimating the mean velocities of overlaid first- and second- trip signals are presented. The return samples are

M. Sachidananda; Dusan S. Zrnic

1999-01-01

198

Recent experiments in Ocean remote sensing with bistatic radar using Navigation Satellite Signals  

Microsoft Academic Search

This paper will present results from a recent airborne campaign to collect and anayze reflected Global Navigation Satellite System (GNSS-R) signals. The objective of this experiment was to test the GNSS Instrument for Multistatic and Occulatation Sensing (GISMOS) and provide additional data for comparison of GNSS-R sea roughness retrievals with in situ measurements. Raw sampled data from the direct GPS

J. K. Voo; J. L. Garrison; J. S. Haase; T. D. Lulich

2009-01-01

199

An expert system for correlation of radar and passive sensor signals  

SciTech Connect

This paper describes a system for automating the correlation task by combining high-speed hardware with symbolic pattern-matching software to perform correlation of active and passive signals in real time. The first section of this paper describes the hardware and software used to implement the inference engine so that correlations can be performed in real time. The second section describes the expert system, with emphasis on the heuristics used to code the correlator efficiently. The final section describes the simulation environment under which the system is operated current efforts, and plans for further development. 2 refs., 2 figs.

Williams, L.C.; Gamberini, R.J.

1989-01-01

200

Basic characteristics of FM-CW radar systems  

Microsoft Academic Search

Due to rapid technological progress in real-time signal processing, FM-CW radar systems are expected to become a more serious competitor to pulse radar systems. This paper deals with basic radar principles such as modulating waveforms and ambiguity functions characteristics. Advantages and disadvantages of FM-CW radar systems are compared to pulse radar systems. The inherent signal processing used in FM-CW radar

L. P. Ligthart; L. R. Nieuwkerk; J. S. Vansinttruyen

1986-01-01

201

Using antennas separated in flight direction to avoid effect of emitter clock drift in geolocation  

SciTech Connect

The location of a land-based radio frequency (RF) emitter is determined from an airborne platform. RF signaling is received from the RF emitter via first and second antennas. In response to the received RF signaling, signal samples for both antennas are produced and processed to determine the location of the RF emitter.

Ormesher, Richard C.; Bickel, Douglas L

2012-10-23

202

Deception jamming modeling in radar sensor networks  

Microsoft Academic Search

In this paper we create a modeling scenario which includes an airborne imaging radar platform, receiving platform and an electronic countermeasure (ECM) platform whose goal is to introduce false target images. We also assume a high-resolution stripmap SAR model operating with several common types of UWB signals, as well as the newly proposed OFDM radar waveforms. OFDM-coded radar signals possess

Jonathan Schuerger; Dmitriy Garmatyuk

2008-01-01

203

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

204

Passive Radar.  

National Technical Information Service (NTIS)

The basic ideas and concepts of one of the newest branches of radar, that of passive radar, are discussed. A great deal of attention is devoted to questions of the use of passive radar by the armed forces. The physical fundamentals of passive radar, and t...

A. G. Nikolaev S. V. Pertsov

1975-01-01

205

Object recognation with surveillance radar systems  

Microsoft Academic Search

In this thesis have written description and principle of radar systems and them classification. As well as radar systems are used where and for what. The most optimal signal transmission and principles of systems in general.

Gun Sergiy

2010-01-01

206

Range Delay Techniques for Radar Target Simulators.  

National Technical Information Service (NTIS)

It was recognized that the Radar Guided Seeker and countermeasure development using flight tests as a primary evaluation tool is costly and insecure from interception of signal and telemetry emenations. Radar Target Simulators were developed which provide...

L. C. Buse

1988-01-01

207

Flashlight radar: A three-dimensional imaging radar  

NASA Astrophysics Data System (ADS)

In support of several programs at Lincoln Laboratory, a small focused-beam polarimetric, millimeter-wave radar scatterometer (an instrument for measuring radar cross section) has been developed. An overview of the design of this Flashlight Radar is presented. Theoretical and empirical studies of antenna performance are discussed. The backscatter theory relating to the characteristics of the Flashlight Radar as a scatterometer is presented, and experimental RCS measurements are compared with theoretical predictions. The data processing steps (polarimetric calibration and compensation, signal processing, and image formation) are described. We show the results of two representative experiments using the Flashlight Radar. The first is a measurement of dihedral and trihedral reflectors with and without radar camouflage. The second is a faster scan of a truck tire, highlighting the radar's fine resolution and its ability to collect three-dimensional data.

Blejer, Dennis J.; Ferranti, Richard L.; Barnes, Richard M.; Irving, William W.; Verbout, Shawn M.

1989-08-01

208

A new frequency domain CFAR algorithm in radar reconnaissance receiver  

Microsoft Academic Search

In view of the requirement of automatic CFAR (Constant False Alarm Rate) detection of pulse radar signal (indicate that the radar signal modulated by periodic rectangular pulses) in the design of radar reconnaissance receiver, a pulse radar signalpsilas DFT (Discrete Fourier Transform) spectrum detection algorithm with the function of CFAR is presented. By researching the threshold generating algorithm of pulse

Luo Yuedong; Chen He; Li Junshan

2008-01-01

209

Active radar jamming  

NASA Astrophysics Data System (ADS)

Active radar jammers are described. In confusion jammers the perturbing action is produced by thermal noise which is intensified, or by a carrier wave modulated by a noise signal, or by a carrier wave which is frequency modulated with a lot of sine waves of different frequencies. There are jammers to be used once, which are fired to the spot or hang from a parachute. Deception jammers (misleading jammers) emit false radar echoes, one or several produced by a repetition system, requiring a certain form of memory. It is shown how to emit varying false distance or velocities, and how to disturb angles in a radar used to guide artillery fire.

Jernemalm, Veine

1988-09-01

210

Theory of Adaptive Radar  

Microsoft Academic Search

This paper reviews the principles of adaptive radar in which both the spatial (antenna pattern) and temporal (Doppler filter) responses of the system are controlled adaptively. An adaptive system senses the angular-Doppler distribution of the external noise field and adjusts a set of radar parameters for maximum signal-to-interference ratio and optimum detection performance. A gradient technique for control of the

L. E. Brennan; L. S. Reed

1973-01-01

211

Terminal Doppler weather radar  

Microsoft Academic Search

The terminal Doppler weather radar (TDWR) system, now under development, will provide automatic detection of microbursts and low-level wind shear. This paper discusses the TDWR performance parameters and describes its structural elements, including the antenna subsystem, the transmitter, the receiver\\/exciter, the digital signal processor, and the radar product generator\\/remote monitoring subsystem. Attention is also given to the processes of the

M. Michelson; W. W. Shrader; J. G. Wieler

1990-01-01

212

Low emittance damping rings  

SciTech Connect

The effects of synchrotron radiation and intrabeam scattering on the equilibrium emittance of electron storage rings are reviewed. Intrabeam scattering is shown to be important for damping rings with the invariant emittance needed for a linear collider operating in the quantum beamstrahlung regime.

Siemann, R.H.

1987-05-05

213

Passive Radar.  

National Technical Information Service (NTIS)

This book sets forth in brief the physical principles of passive radar, describes the functional diagrams and circuit peculiarities of the apparatus, and offers recommendations for modifying radar receivers to adapt them for receiving natural radio-freque...

A. G. Nikolaev S. V. Pertsov

1975-01-01

214

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

215

Region-Enhanced Passive Radar Imaging  

Microsoft Academic Search

Abstract We adapt and apply a recently-developed region-enhanced synthetic aperture radar (SAR) image reconstruction technique to the problem of passive radar imaging. One goal in passive radar imaging is to form images of aircraft using signals transmitted by commercial radio and television stations that are reflected from the objects of interest. This involves reconstructing an image from sparse samples of

Mujdat Cetin; Aaron D. Lanterman

2004-01-01

216

a Satellite-Based Radar Wind Sounder  

Microsoft Academic Search

The objective of this study 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, such as the antenna scan pattern, tracking the Doppler shift caused by satellite motion, and backscattering of radar signals from different types of clouds,

Weizhuang Xin

1991-01-01

217

Tomographic synthesis applied to radar \\/STAR  

Microsoft Academic Search

A real time radar target imaging procedure based on tomographic synthesis is discussed. The procedure, which can be used with an incoherent high range resolution radar (or a CW high Doppler resolution radar), employs a previously described (Le Chevalier et al., 1977) syntactic signal processing algorithm to detect and track a bright point on successive unit-impulse responses in real time.

F. Le Chevalier; C. Fugier-Garrel

1979-01-01

218

Systolic architectures for radar CFAR detectors  

Microsoft Academic Search

Radar constant false alarm rate (CFAR) detectors, which are adaptive threshold detectors used to compensate for unknown noise environments, are discussed. Although the signal processing theory for CFAR detection is advanced, applications lag because of the high throughput required in radar. This intensive computational requirement (a data rate of at least 20 MHz for most search radars) cannot be met

J.-N. Hwang; J. A. Ritcey

1990-01-01

219

Portable emittance measurement device  

SciTech Connect

In Institute for Theoretical and Experimental Physics (ITEP) the portable emittance measurements device is developed. It provides emittance measurements both with ''pepper-pot'' and ''two slits'' methods. Depending on the method of measurements, either slits or pepper-pot mask with scintillator are mounted on the two activators and are installed in two standard Balzer's cross chamber with CF-100 flanges. To match the angle resolution for measured beam, the length of the stainless steel pipe between two crosses changes is adjusted. The description of the device and results of emittance measurements at the ITEP ion source test bench are presented.

Liakin, D.; Seleznev, D.; Orlov, A.; Kuibeda, R.; Kropachev, G.; Kulevoy, T.; Yakushin, P. [Institute for Theoretical and Experimental Physics, Moscow 117218 (Russian Federation)

2010-02-15

220

Terminal Doppler weather radar  

NASA Astrophysics Data System (ADS)

The terminal Doppler weather radar (TDWR) system, now under development, will provide automatic detection of microbursts and low-level wind shear. This paper discusses the TDWR performance parameters and describes its structural elements, including the antenna subsystem, the transmitter, the receiver/exciter, the digital signal processor, and the radar product generator/remote monitoring subsystem. Attention is also given to the processes of the base data formation, point target removal, signal-to-noise thresholding, and velocity de-aliasing and to the TDWR algorithms and displays. A schematic diagram of the TDWR system is presented.

Michelson, M.; Shrader, W. W.; Wieler, J. G.

1990-02-01

221

Wavelets and impulse radar  

NASA Astrophysics Data System (ADS)

The signal generated by avalanche discharge circuitry that drives optical flash for cameras is ultra wideband and suitable as the excitation waveform for an Impulse Radar when transmitted through an appropriate antenna. In this paper, we experimentally and theoretically show that the Impulse Radar's radiated transmitted EM waves satisfy the admissibility condition of wavelets, i.e. (i) a finite power spectral density psd=<|S(f)|2>< and (ii) zero total area under the undulated wave amplitudes. If the radiated environment is linear (the natural scene), then the received signal also satisfies the admissibility condition.

Szu, Harold; Hsu, Charles; Scheff, Kim; Hansen, Peter; Willey, Jeff

2009-04-01

222

Optical-radar detection for radio engineers  

NASA Astrophysics Data System (ADS)

The principal characteristics of optical-radar detection techniques are examined and compared with those of conventional radar techniques. Consideration is given to the physical processes underlying the formation, transmission, and reception of radar signals, the principles of detection, and the measurement of target parameters. The preferred applications of electron-optic and radio techniques are identified. The treatment is based on statistical methods of radar detection and the semiclassical theory of photoemission.

Vorobev, V. I.

223

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

224

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

225

Improvements of radar clutter classification in air traffic control environment  

Microsoft Academic Search

The use of adaptive technologies may prove useful in the processing of radar signals. The proposed radar clutter classificator is aimed to improve the detection of snow clutter presence in data acquired by a ground radar system in an air traffic control environment. Each plot detected in the radar image is processed in order to extract a series of features

L. Pierucci; L. Bocchi

2007-01-01

226

The Retrieval of Ice-Cloud Properties from Cloud Radar and Lidar Synergy.  

NASA Astrophysics Data System (ADS)

Clouds are an important component of the earth's climate system. A better description of their microphysical properties is needed to improve radiative transfer calculations. In the framework of the Earth, Clouds, Aerosols, and Radiation Explorer (EarthCARE) mission preparation, the radar-lidar (RALI) airborne system, developed at L'Institut Pierre Simon Laplace (France), can be used as an airborne demonstrator. This paper presents an original method that combines cloud radar (94-95 GHz) and lidar data to derive the radiative and microphysical properties of clouds. It combines the apparent backscatter reflectivity from the radar and the apparent backscatter coefficient from the lidar. The principle of this algorithm relies on the use of a relationship between the extinction coefficient and the radar specific attenuation, derived from airborne microphysical data and Mie scattering calculations. To solve radar and lidar equations in the cloud region where signals can be obtained from both instruments, the extinction coefficients at some reference range z0 must be known. Because the algorithms are stable for inversion performed from range z0 toward the emitter, z0 is chosen at the farther cloud boundary as observed by the lidar. Then, making an assumption of a relationship between extinction coefficient and backscattering coefficient, the whole extinction coefficient, the apparent reflectivity, cloud physical parameters, the effective radius, and ice water content profiles are derived. This algorithm is applied to a blind test for downward-looking instruments where the original profiles are derived from in situ measurements. It is also applied to real lidar and radar data, obtained during the 1998 Cloud Lidar and Radar Experiment (CLARE'98) field project when a prototype airborne RALI system was flown pointing at nadir. The results from the synergetic algorithm agree reasonably well with the in situ measurements.

Tinel, Claire; Testud, Jacques; Pelon, Jacques; Hogan, Robin J.; Protat, Alain; Delanoë, Julien; Bouniol, Dominique

2005-06-01

227

Gallium-Aluminum-Arsenide Power Infrared Emitters.  

National Technical Information Service (NTIS)

Two types of (Ga, Al)As light emitters for the unguided (via air) signal transmission were developed. Depending on the Al content they emit between 780 and 900 nm. The technology of these diodes is based on the liquid phase epitaxy process of (Ga, Al)As o...

J. Aengenheister S. Leibenzeder

1983-01-01

228

Passive Radar Tracking Apparatus.  

National Technical Information Service (NTIS)

The radar system tracks a target whether it generates a signal of its own or not and may be used to sense noise energy radiated by the sun, other objects, or other celestial bodies. The system includes an antenna assembly of four horns arranged in a recta...

D. K. Barton W. J. Rose

1965-01-01

229

47 CFR 15.515 - Technical requirements for vehicular radar systems.  

Code of Federal Regulations, 2010 CFR

...requirements for vehicular radar systems. 15.515...requirements for vehicular radar systems. (a) Operation...section is limited to UWB field disturbance...signal. (b) The UWB bandwidth of a vehicular radar system operating...

2009-10-01

230

47 CFR 15.515 - Technical requirements for vehicular radar systems.  

Code of Federal Regulations, 2010 CFR

...requirements for vehicular radar systems. 15.515...requirements for vehicular radar systems. (a) Operation...section is limited to UWB field disturbance...signal. (b) The UWB bandwidth of a vehicular radar system operating...

2010-10-01

231

Cancer from internal emitters  

SciTech Connect

Irradiation from internal emitters, or internally deposited radionuclides, is an important component of radiation exposures encountered in the workplace, home, or general environment. Long-term studies of human populations exposed to various internal emitters by different routes of exposure are producing critical information for the protection of workers and members of the general public. The purpose of this report is to examine recent developments and discuss their potential importance for understanding lifetime cancer risks from internal emitters. The major populations of persons being studied for lifetime health effects from internally deposited radionuclides are well known: Lung cancer in underground miners who inhaled Rn progeny, liver cancer from persons injected with the Th-containing radiographic contrast medium Thorotrast, bone cancer from occupational or medical intakes of {sup 226}Ra or medical injections of {sup 224}Ra, and thyroid cancer from exposures to iodine radionuclides in the environment or for medical purposes.

Boecker, B.B.; Griffith, W.C. Jr.

1995-10-01

232

Doppler Radar  

Microsoft Academic Search

This paper contains a discussion of the principle of operation of cw doppler search radar systems and an analysis of their performance capabilities, with particular emphasis on the elimination of fixed targets. A comparison of these systems and MTI pulse radar systems is made.

E. J. Barlow

1949-01-01

233

TRMM Radar.  

National Technical Information Service (NTIS)

The results of a conceptual design study and the performance of key components of the Bread Board Model (BBM) of the Tropical Rainfall Measuring Mission (TRMM) radar are presented. The radar, which operates at 13.8 GHz and is designed to meet TRMM mission...

K. Okamoto

1993-01-01

234

GSM passive radar for medium range surveillance  

Microsoft Academic Search

This paper presents a passive radar system using GSM as illuminator of opportunity. The new feature is the used high performance uniform linear antenna (ULA) for extracting both the reference and the echo signal in a software defined radar. The signal processing steps used by the proposed scheme are detailed and the feasibility of the whole system is proved by

Reda Zemmari; Ulrich Nickel; Wulf-Dieter Wirth

2009-01-01

235

A general radar surface target echo simulator  

Microsoft Academic Search

A general radar echo simulator system proposed in this paper is to satisfy the various needs of the radar signal processor testing. This simulator is based on the type of echo data playback device, the surface target echo data is pre-calculated and stored in the device at first, then according to the external timing PRI signal, echo data is read

Chengfa Xu; Jingliang Bai; Ronggang Wu; Yongbin Hong

2010-01-01

236

A 94GHz Doppler radar for cloud observations  

Microsoft Academic Search

A Doppler radar operating at 3.2 mm wavelength was designed and assembled primarily for observation of clouds and precipitation. Phase detection of the radar signals which is required for Doppler operation is implemented through the use of a coherent oscillator phase locked on the transmitter pulse and used as a reference in the phase detector. The radar and associated signal

Roger Lhermitte

1987-01-01

237

Propagation effects in tactical radars  

NASA Astrophysics Data System (ADS)

Tactical battlefield radars are employed in surveillance and target acquisition roles at ranges of approximately 1 to 20 km, their main targets being enemy ground vehicles and personnel. As with all types of radar the operating environment has a significant effect on the design and performance of these systems and propagation considerations are an important factor. The major propagation factors which limit the performance of tactical radars are the availability of line of sight, ground clutter, and effects of the weather. The ways in which propagation factors affect the choice of such radar parameters as frequency, polarisation, and RF waveform are discussed, and the ways in which propagation constraints can be minimised by the design of the signal processing system are considered. In an EW environment an important operational requirement is to minimize the probability of the location of the position of the radar by the enemy. Propagation effects such as multipath and diffraction are considered in broad terms in this context.

Prew, B. A.

1982-04-01

238

Remarks on Transverse RMS Emittance.  

National Technical Information Service (NTIS)

This report presents some considerations on the radial rms emittance of linear accelerator beams. In case of acceleration, a constant normalized rms emittance results if each beam particle is described by the same linear differential equation. The second ...

M. Pabst

1981-01-01

239

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

240

Millimeter radar improves target identification  

NASA Astrophysics Data System (ADS)

Recently developed millimeter wave radar has advantages for target identification over conventional microwave radar which typically use lower frequencies. We describe the pertinent features involved in the construction of the new millimeter wave radar, the pseudo-optical cavity source and the quasi-optical duplexer. The long wavelength relative to light allows the radar beam to penetrate through most weather because the wavelength is larger than the particle size for dust, drizzle rain, fog. Further the mm wave beam passes through an atmospheric transmission window that provides a dip in attenuation. The higher frequency than conventional radar provides higher Doppler frequencies, for example, than X-band radar. We show by simulation that small characteristic vibrations and slow turns of an aircraft become visible so that the Doppler signature improves identification. The higher frequency also reduces beam width, which increases transmit and receive antenna gains. For the same power the transmit beam extends to farther range and the increase in receive antenna gain increases signal to noise ratio for improved detection and identification. The narrower beam can also reduce clutter and reject other noise more readily. We show by simulation that the radar can be used at lower elevations over the sea than conventional radar.

McAulay, Alastair D.

2011-05-01

241

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

242

Fiber optic delay lines for radar applications  

NASA Astrophysics Data System (ADS)

Novel applications of fiber optic delay lines to improve the capability and performance of radar repeater and phase noise test sets are described. Using a 2.25-km long fiber optic link, a generation of an ideal target for a radar repeater test set, and measurement of phase noise closer than 100 Hz to a 9.6-GHz radar carrier signal using a delay line discriminator phase noise test set, are demonstrated. FM and AM signal-to-noise measurements were made to determine the performance capability of the 10-GHz modulated fiber optic links for the radar applications.

Newberg, I. L.; Gee, C. M.; Thurmond, G. D.; Yen, H. W.

1988-01-01

243

Synchronisation of bistatic radar systems  

Microsoft Academic Search

Bistatic radar is gaining more and more interest over the last years. It offers more freedom to deploy the transmitter and the receiver, e.g. in a way to enhance the signature of stealthy targets. Furthermore, the bi- or multistatic system can be realized without using expensive transmit\\/receive-modules. An additional feature of bistatic radar is that continuous wave signals can be

M. Weib

2004-01-01

244

Principals of Radar and Meteorological Radar Devices.  

National Technical Information Service (NTIS)

Three meteorological radar units are described: the Malachite radiotheodolite with rangefinder attachment, the Meteorite radar station, and the MRL radar station. The principles of operation of these systems are given along with circuit descriptions and e...

O. G. Korol R. D. Chernyak

1973-01-01

245

Weibull-distributed radar clutter reflected from sea ice  

Microsoft Academic Search

Sea-ice clutter was measured using an X-band radar which is located at the city of Mombetsu in Hokkaido. The pulse width of the radar was 80 ns. To sample at 40 ns and record digitally, an emitter-coupled logic (ECL) was used as a high-speed IC. The sampled data were first transferred to a 64-kbyte dynamic-memory board and then to a

Hiroshi Ogawa; Matsuo Sekine; Toshimitsu Musha; Masaaki Aota; Masayuki Ohi

1987-01-01

246

Radar techniques program  

Microsoft Academic Search

This is the fifth Quarterly Technical Summary covering the development of an airborne Multiple-Antenna Moving-Target Surveillance Radar (MASR) which employs special antenna and signal-processing techniques to provide continuous, wide-area surveillance of moving targets on or near the ground. Such a sensor, equipped with an appropriate data-reduction facility, can provide useful real-time information to a Tactical Air Control System. A DeHavilland

C. E. Muehe

1974-01-01

247

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

248

Composite emitters for TPV systems  

SciTech Connect

One important aspect of thermophotovoltaic (TPV) power systems is the need for an emitter which can produce radiation whereby electricity can be generated from photovoltaic cells. We have developed two types of emitter configurations which can be thermally excited by a heat source. These two configurations allow the emitter to produce the requisite emissions for matching to photovoltaic cells. The first emitter type, the selective line emitter, made from oxides of the rare earth metals such as erbia and holmia. These emitters are made through a specialized series of processes which begin with nitrates of the rare earth metal and end with rare earth oxide filaments. These emitters produce a discrete line output which can be used with photovoltaic cells whose bandgap is centered at this selective line wavelength. The second approach considered is to produce `modified` blackbody emitters which can withstand sufficiently high temperature operation and produce a significant amount of radiant energy. This requires the development of tandem cells which can utilize a significant portion of the emission spectrum. For both emitter types, conventional paper making techniques have been used to combine materials suitable as binders with the radiating material. As a result, this technique allows for fabrication of large area robust emitters which were heretofore unobtainable. Robust emitters made from holmium oxide have exhibited line emission with peak to background ratios greater than 6 to 1. This radiator will be described in some detail as representative of the process and will be used to illustrate the manufacturing technology developed at Auburn University. In this paper, we will describe the techniques for manufacturing both types of emitters, characterize the spectral characteristics, and discuss preliminary designs which would have sufficient area and robustness for various applications. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Adair, P.L.; Rose, M.F. [Space Power Institute, 231 Leach Center, Auburn University, Alabama 36849 (United States)

1995-01-05

249

Experimental investigation of impulse radar for mitigation of effects of radar absorbing materials  

Microsoft Academic Search

The response of a UWB signal acting on coating radar absorbing material (RAM) targets have been investigated experimentally by the time-domain method and the frequency-domain method. It is shown that the UWB signal is 10-12 dB superior to the narrowband signal of conventional radar for anti-coating RAM targets. It has been clearly indicated that the UWB signal has good capabilities

Jianguo He; Zhongliang Lu; Yi Su

1992-01-01

250

Radar Altimeter Instrument for POEM-1 Mission.  

National Technical Information Service (NTIS)

RA-2 is a fully redounded nadir pointing pulse limited Radar Altimeter (RA) operating with a single antenna dish at 13.8 GHz and at 3.2 GHz. Its design is derived from the ERS-1 RA, but its new signal processing, which autonomously adapts the radar resolu...

A. Resti G. Levrini

1992-01-01

251

Bistatic radar denial\\/embedded communications via waveform diversity  

Microsoft Academic Search

Use of an interferometer along with a host radar is proposed for simultaneously achieving coherent reference denial and embedded communications. To prevent self-jamming, spatial orthogonality is achieved between the interferometer antenna pattern and main beam of the host radar. Costas and orthogonal frequency division multiplexing (OFDM) signals are suggested for the host radar and interferometer, respectively. The effectiveness of the

P. Antonik; R. Bonneau; R. Brown; S. Ertan; V. Vannicola; D. Weiner; M. Wicks

2001-01-01

252

Complementary Waveforms for Sidelobe Suppression and Radar Polarimetry.  

National Technical Information Service (NTIS)

Advances in active sensing are enabled by the ability to control new degrees of freedom and each new generation of radar platforms requires fundamental advances in radar signal processing. The advent of phased array radars and space-time adaptive processi...

A. Pezeshki A. R. Calderbank Y. Chi

2010-01-01

253

High power ultra wideband radar exotic material response  

Microsoft Academic Search

This paper is the first of two that present analytical and numerical analysis of high power and ultra wide band radars interacting with EMI and radar suppression materials. Magnetic materials are often used in isolators, thin film EMI materials and\\/or appliques. Such magnetic composites may be exposed to wide band and\\/or high power signals in operational radar systems. We describe

Rick L. Moore; John Meadors; Robert Rice

2008-01-01

254

Convergence of ESM sensors and passive covert radar  

Microsoft Academic Search

This paper explains the convergence of ESM sensors and passive covert radar (PCR) by presenting the results of field tests with the application of an experimental wideband digital ESM receiver as a sensor in bistatic configuration for PCR. Exploitation of an a priori unknown radar illumination gives the principal possibility of detecting moving targets. A LPI radar with FMCW signals

Dietmar Matthes

2005-01-01

255

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

256

Impact of HRR radar processing on moving target identification performance  

Microsoft Academic Search

Airborne radar tracking in moving ground vehicle scenarios is impacted by sensor, target, and environmental dynamics. Moving targets can be assessed with 1-D High Range Resolution (HRR) Radar profiles with sufficient signal-to-noise (SNR) present which contain enough feature information to discern one target from another to help maintain track or to identify the vehicle. Typical radar clutter suppression algorithms developed

Bart Kahler; Erik Blasch

2009-01-01

257

Target identification performance improvement from enhanced HRR radar clutter suppression  

Microsoft Academic Search

Airborne radar tracking in moving ground vehicle scenarios is impacted by sensor, target, and environmental dynamics. Moving targets can be assessed with 1-D High Range Resolution (HRR) Radar profiles with sufficient signal-to-noise (SNR) present which contain enough feature information to discern one target from another to help maintain track or to identify the vehicle. Typical radar clutter suppression algorithms developed

Bart Kahler; Erik Blasch

2009-01-01

258

Lightweight SAR GMTI radar technology development  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

259

Array radars - An update. II  

NASA Astrophysics Data System (ADS)

Research aimed at improving array radars is reviewed. Advances in MMICs, the use of HEMT low noise amplifiers for analog and digital circuitry, the application of VHSIC chips to the programmable signal processor of the F-16 airborne fire control radar, Si compiler language, memory chips, and GHz and GaAs logic are discussed. Consideration is given to CMOS gate arrays, floating point chips, a single-chip digital signal processor, systolic array architectures, radiation hardened chips, digital beamforming, distributed beamsteering computers, fiber optics, flat low voltage displays, and adaptive-adaptive array processing.

Brookner, Eli

1987-03-01

260

Results from an experimental continuous wave low probability of intercept bistatic radar - the first steps toward multistatic radar  

Microsoft Academic Search

The Norwegian Defence Research Establishment (FFI) has developed an experimental continuous wave (CW) low probability of intercept (LPI) bistatic radar. The radar is transmitting a CW binary phase coded signal at a maximum power of 1 W. The radar has been used to detect different targets in various trials. Selected results are presented, and future work is indicated.

K. E. Olsen; T. Johnsen; S. Johnsrud; R. Gundersen; H. Bjordal; I. Tansem; P. Sornes

2003-01-01

261

Shipboard Radar.  

National Technical Information Service (NTIS)

The navigational radar 'Stvor' is designed for installation on ships of the shipping fleet and also on marine and river boats of low and medium tonnage. A 'Stvor' station enables ships to navigate in zero visibility -- in fog, at night, etc. Because of it...

1968-01-01

262

Radar Antenna.  

National Technical Information Service (NTIS)

An antenna is described for range-gated, pulse doppler, radar systems. The antenna includes first and second, shortened, half-wave dipoles and first and second reflecting screens. One dipole is fed through a fixed 22 1/2 degree phase-shift network while t...

O. E. Rittenback

1978-01-01

263

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

264

Solar Radar Astronomy with LOFAR  

NASA Astrophysics Data System (ADS)

A new approach to the study of the Sun's corona and its dynamical processes is possible with radar investigations in the frequency range of about 10-50 MHz. The range of electron densities of the solar corona is such that radio waves at these frequencies can provide diagnostic radar echoes of large scale phenomena such as coronal mass ejections (CMEs). We expect that the frequency shift imposed on the echo signal by an earthward-moving CME will provide a direct measurement of the velocity, thereby providing a good estimate of the arrival time at Earth. It is known that CMEs are responsible for the largest geomagnetic storms at Earth, which are capable of causing power grid blackouts, satellite electronic upsets, and degradation of radio communications circuits. Thus, having accurate forecasts of potential CME-initiated geomagnetic storms is of practical space weather interest. New high power transmitting arrays are becoming available, along with proposed modifications to existing research facilities, that will allow the use of radio waves to study the solar corona by the radar echo technique. Of particular interest for such solar radar investigations is the bistatic configuration with the Low Frequency Array (LOFAR). The LOFAR facility will have an effective receiving area of about 1 square km at solar radar frequencies. Such large effective area will provide the receiving antenna gain needed for detailed investigations of solar coronal dynamics. Conservative estimates of the signal-to-noise ratio for solar radar echoes as a function of the integration time required to achieve a specified detection level (e.g., ~ 5 dB) indicate that time resolutions of 10s of seconds can be achieved. Thus, we are able to resolve variations in the solar radar cross section on time scales which will provide new information on the plasma dynamical processes associated with the solar corona, such as CMEs. It is the combination of high transmitted power and large effective receiving area that makes possible the significant performance indicated. We will review early and current solar radar investigations and proposed approaches to future radar studies of the solar corona. Solar radar experiments were done almost from the beginning of the modern era of space physics research and has a very interesting history. In addition to re-opening the solar radar window, LOFAR will also be able to open new studies of planetary hard surfaces (e.g., the Moon and asteroids), and solar system plasmas (solar wind, magnetosphere, dusty plasmas, comets).

Rodriguez, P.

2003-04-01

265

Reduction of interference in automotive radars using multiscale wavelet transform  

Microsoft Academic Search

A technique is presented to minimise false decisions in automotive radars operating in close proximity. The technique also reduces the requirement on the power of the radar as signals can be detected with very low signal to noise ratios. The signal processing is achieved in real time using a field programmable array

Ehab Elsehely; Mohamed I. Sobhy

2001-01-01

266

Ultra-wideband radar using Fourier synthesized waveforms  

Microsoft Academic Search

Traditional methods of ultra-wideband (UWB) radar signal generation suffer from several disadvantages such as low antenna radiation efficiency and lack of accurate control of signal parameters like pulse shape, pulse repetition interval (PRI), and its spectrum. UWB signals can be generated by expanding the desired radar waveform in a Fourier series and then synthesizing the waveform by generating the individual

Gurnam Singh Gill

1997-01-01

267

Performance analysis of UWB impulse radar using parallel IPCP receiver  

Microsoft Academic Search

UWB impulse radar has high accuracy of measurement because it uses a transmitted signal whose pulse length is below some nanosecond. In this paper, we propose two novel inter-period correlation processing (IPCP) receivers for UWB impulse radar. The conventional IPCP receiver uses the signal periodicity of signals, so it avoids estimation of unknown parameters determined by the targets and propagation.

Hiroyuki Hatano; Hiraku Okada; Takaya Yamazato; Masaaki Katayama

2004-01-01

268

EMITTANCE COMPENSATION FOR MAGNETIZED BEAMS  

SciTech Connect

Emittance compensation is a well established technique for minimizing the emittance of an electron beam from a RF photo-cathode gun. Longitudinal slices of a bunch have a small emittance, but due to the longitudinal charge distribution of the bunch and time dependent RF fields they are not focused in the same way, so that the direction of their phase ellipses diverges in phase space and the projected emittance is much larger. Emittance compensation reverses the divergence. At the location where the slopes of the phase ellipses coincide the beam is accelerated, so that the space charge forces are reduced. A recipe for emittance compensation is given in. For magnetized beams (where the angular momentum is non-zero) such emittance compensation is not sufficient because variations in the slice radius lead to variations in the angular speed and therefore to an increase of emittance in the rotating game. We describe a method and tools for a compensation that includes the beam magnetization.

KEWISCH,J.; CHANG, X.

2007-06-25

269

Radar detection of Iapetus  

NASA Astrophysics Data System (ADS)

We have obtained echoes from the bright, trailing hemisphere of Iapetus using the Arecibo Observatory's 13-cm radar system on three dates in January 2002. A circularly polarized signal was transmitted and an echo in the opposite circular (OC) sense to that transmitted was clearly received along with a much weaker detection of echo power in the same circular (SC) sense. Prior to this experiment, one expectation may have been that the radar scattering properties of Iapetus may behave like the similar atmosphere-less, icy surfaces of the Galilean satellites which, due to an efficient multiple scattering mechanism, are strong backscatterers with SC reflections stronger than their OC reflections. Instead we find that Iapetus' radar cross section and polarization properties are very different from those of the icy Galilean satellites, and more reminiscent of less efficient and less exotic scattering mechanisms such as dominate the echoes from inner Solar System targets. Thus these observations indicate that there is a significant difference between the surface properties of Iapetus and the icy Galileans despite their overall classification as low temperature, water ice surfaces. A plausible explanation for Iapetus' inefficient scattering is that contaminants in the water ice increase the absorption of the signal and suppress any multiple scattering. Likely contaminants on Iapetus are ammonia and the dark material from Cassini Regio embedded below the surface. Proposed observations will seek to measure Iapetus' radar scattering law and to detect the dark, leading side which was not targeted during this observing session. The Arecibo Observatory is part of the National Astronomy and Ionosphere Center, which is operated by Cornell University under a cooperative agreement with the National Science Foundation.

Black, G. J.; Campbell, D. B.; Carter, L. M.; Ostro, S. J.

2002-09-01

270

Partial treatment of wind turbine blades with radar absorbing materials (RAM) for RCS reduction  

Microsoft Academic Search

The application of radar absorbing materials (RAM) in order to reduce the interference of wind farms with radar systems is considered as a possible mitigation solution. This paper will address the key challenges when trying to efficiently apply RAM to certain parts of the wind turbine blades to significantly reduce the scattering of radar signals. Modeling of the radar cross-section

Laith Rashid; Anthony Brown

2010-01-01

271

Mercury's Perihelion Advance: Determination by Radar.  

National Technical Information Service (NTIS)

Measurements of echo delays of radar signals transmitted from Earth to Mercury have yielded an accurate value for the advance of the latter's perihelion position. Given that the Sun's gravitational quadrupole moment is negligible, the result in terms of t...

D. B. Campbell G. H. Pettingill I. I. Shapiro M. E. Ash R. P. Ingalls

1972-01-01

272

Theoretical Fundamentals of Radar.  

National Technical Information Service (NTIS)

The book examines the principles of radar, methods of coordinate measurement and scanning and circuits for radar stations of three types: with an operator, a continuous computer installation and a digital computer. It presents the characteristics of radar...

A. A. Korostelev A. V. Petrov N. I. Burenin V. E. Dulevich Y. A. Melnik

1967-01-01

273

Covert Operation of Surveillance Noise Radar  

Microsoft Academic Search

paper is devoted to solving the functional problem of the ground-based surveillance pulse noise radar for covert operation in the presence of operative electronic support measures system (ESMS). The radiation covertness is provided by selecting space-time frequency parameters of noise sounding signals and the corresponding structures of noise radar returned-signal processing, and by the definite radiation strategy for sounding local

Valeriy Kantsedal; Konstantin Lukin

2006-01-01

274

CFAR detection for multistatic radar  

Microsoft Academic Search

In this paper a multistatic radar system with n transmitters and one receiver is considered and several constant false alarm rate (CFAR) algorithms for detection are introduced. The decision statistics of the proposed detectors are the sum of the n largest returning signals in an array of N+n range cells. It is shown that the proposed decision statistic satisfies the

Vahideh Amanipour; Ali Olfat

2011-01-01

275

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

276

Radar clutter classification  

NASA Astrophysics Data System (ADS)

The problem of classifying radar clutter as found on air traffic control radar systems is studied. An algorithm based on Bayes decision theory and the parametric maximum a posteriori probability classifier is developed to perform this classification automatically. This classifier employs a quadratic discriminant function and is optimum for feature vectors that are distributed according to the multivariate normal density. Separable clutter classes are most likely to arise from the analysis of the Doppler spectrum. Specifically, a feature set based on the complex reflection coefficients of the lattice prediction error filter is proposed. The classifier is tested using data recorded from L-band air traffic control radars. The Doppler spectra of these data are examined; the properties of the feature set computed using these data are studied in terms of both the marginal and multivariate statistics. Several strategies involving different numbers of features, class assignments, and data set pretesting according to Doppler frequency and signal to noise ratio were evaluated before settling on a workable algorithm. Final results are presented in terms of experimental misclassification rates and simulated and classified plane position indicator displays.

Stehwien, Wolfgang

1989-11-01

277

Waveform design for MIMO radar using Kronecker structured matrix estimation  

Microsoft Academic Search

The multiple-input multiple-output (MIMO) radar system is a new kind of radar technology. It can choose flexibly the probing signals transmitted via its antennas or increase the inter-element distance to reduce the cross-correlation of the signals, so that the spatial diversity gain can be obtained. Waveform design is one of the important topics of the MIMO radar. We discuss here

Yijia Yang; Zishu He; Wei Xia

2008-01-01

278

DC coupled Doppler radar physiological monitor.  

PubMed

One of the challenges in Doppler radar systems for physiological monitoring is a large DC offset in baseband outputs. Typically, AC coupling is used to eliminate this DC offset. Since the physiological signals of interest include frequency content near DC, it is not desirable to simply use AC coupling on the radar outputs. While AC coupling effectively removes DC offset, it also introduces a large time delay and distortion. This paper presents the first DC coupled IQ demodulator printed circuit board (PCB) design and measurements. The DC coupling is achieved by using a mixer with high LO to RF port isolation, resulting in a very low radar DC offset on the order of mV. The DC coupled signals from the PCB radar system were successfully detected with significant LNA gain without saturation. Compared to the AC coupled results, the DC coupled results show great advantages of less signal distortion and more accurate rate estimation. PMID:22254704

Zhao, Xi; Song, Chenyan; Lubecke, Victor; Boric-Lubecke, Olga

2011-01-01

279

Diamondoid monolayers as electron emitters  

DOEpatents

Provided are electron emitters based upon diamondoid monolayers, preferably self-assembled higher diamondoid monolayers. High intensity electron emission has been demonstrated employing such diamondoid monolayers, particularly when the monolayers are comprised of higher diamondoids. The application of such diamondoid monolayers can alter the band structure of substrates, as well as emit monochromatic electrons, and the high intensity electron emissions can also greatly improve the efficiency of field-effect electron emitters as applied to industrial and commercial applications.

Yang, Wanli (El Cerrito, CA); Fabbri, Jason D. (San Francisco, CA); Melosh, Nicholas A. (Menlo Park, CA); Hussain, Zahid (Orinda, CA); Shen, Zhi-Xun (Stanford, CA)

2012-04-10

280

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

281

Ground-Penetrating Radar Calibration at the Virginia Smart Road and Signal Analysis to Improve Prediction of Flexible Pavement Layer Thicknesses.  

National Technical Information Service (NTIS)

A ground-penetrating radar (GPR) system was used to collect data over the different pavement sections of the Virginia Smart Road from June 1999 until December 2002. Three antennae at different frequencies were used for this research. The collected data we...

I. L. Al-Qadi S. Lahouar A. Loulizi

2005-01-01

282

Use of radar polarimetric information in CFAR and classification algorithms  

Microsoft Academic Search

This paper shows how the additional information obtained from a coherent polarimetric radar can be used in signal processing, and shows the advantages of the multivariate polarimetric processing compared to the normally used one channel processing. Further, the overall signal processing procedure for a ground-based radar using polarimetric information is shown. The new concepts of a polarimetric-CFAR and a polarimetric

G. Wanielik; D. J. R. Stock

1989-01-01

283

CFAR Target Detection Based on Gumbel Distribution for HF Radar  

Microsoft Academic Search

High frequency (HF) radars are capable to detect and track targets at extremely long ranges. But the signal environment that includes external noise, different kinds of clutter and interference will significantly limit the detection and system capability. This paper considers a new approach to solve the target detection problem in a complex HF radar signal environment. It uses conventional constant

A. L. Dzvonkovskaya; H. Rohling

2006-01-01

284

Initialization Analysis of IIR Ground Clutter Filter in Doppler Weather Radar  

Microsoft Academic Search

This paper analyzes the initialization of IIR ground clutter filter (GCF) in Doppler weather radar. The transients of IIR GCF degrade the theoretical frequency response and different initialization technique produces different suppression characteristic. The initialization performance is tested both with a simulated weather radar signal and an actual weather radar signal. We explore the relation between clutter suppression ratio (the

Yuchun Gao; Yan Liu; He Jianxin

2007-01-01

285

Semi-Active Missile Seeker Circuitry Compatible with Conventional Coherent and/or Spread Spectrum Radars.  

National Technical Information Service (NTIS)

A semi-active missile homes in on reflected radar signals from the target. The seeker sends back to the radar system information concerning its internal coherent local oscillator which is proportional to the frequency of the reflected radar signal it rece...

C. H. Cash R. H. Fletcher

1979-01-01

286

Sampling rate influence on detection performance of CFAR algorithms implemented in radar extractor  

Microsoft Academic Search

A radar extractor based on a two-processor digital signal-processing (DSP) card implemented in a standard personal computer (PC) has been developed. A constant false alarm rate (CFAR) processor is applied as a part of radar extractor algorithms. Some particular problems related to the CFAR automatic detection of radar signals are investigated, from theoretical and practical point of view, and given

Miroslav M. Petrovic; Dragan D. Dimitrijevic; Aleksandar T. Kostic

2001-01-01

287

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

288

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

289

Target Recognition Using Linear Classification of High Range Resolution Radar Profiles.  

National Technical Information Service (NTIS)

High Range Resolution (HRR) radar profiles map three-dimensional target characteristics onto one-dimensional signals that represent reflected radar intensity along target extent. In this thesis, second through fourth statistical moments are extracted from...

R. A. Diaz

2004-01-01

290

Comet radar explorer  

NASA Astrophysics Data System (ADS)

The Comet Radar Explorer (CORE) is designed to perform a comprehensive and detailed exploration of the interior, surface, and inner coma structures of a scientifically impor-tant Jupiter family comet. These structures will be used to investigate the origins of cometary nuclei, their physical and geological evolution, and the mechanisms driving their spectacular activity. CORE is a high heritage spacecraft, injected by solar electric propulsion into orbit around a comet. It is capable of coherent deep radar imaging at decameter wavelengths, high resolution stereo color imaging, and near-IR imaging spectroscopy. Its primary objective is to obtain a high-resolution map of the interior structure of a comet nucleus at a resolution of ¿100 elements across the diameter. This structure shall be related to the surface geology and morphology, and to the structural details of the coma proximal to the nucleus. This is an ideal complement to the science from recent comet missions, providing insight into how comets work. Knowing the structure of the interior of a comet-what's inside-and how cometary activity works, is required before we can understand the requirements for a cryogenic sample return mission. But more than that, CORE is fundamental to understanding the origin of comets and their evolution in time. The mission is made feasible at low cost by the use of now-standard MARSIS-SHARAD reflec-tion radar imaging hardware and data processing, together with proven flight heritage of solar electric propulsion. Radar flight heritage has been demonstrated by the MARSIS radar on Mars Express (Picardi et al., Science 2005; Plaut et al., Science 2007), the SHARAD radar onboard the Mars Reconnaissance Orbiter (Seu et al., JGR 2007), and the LRS radar onboard Kaguya (Ono et al, EPS 2007). These instruments have discovered detailed subsurface structure to depths of several kilometers in a variety of terrains on Mars and the Moon. A reflection radar deployed in orbit about a comet will enjoy significant simplifying benefits compared to using the same instrument for Mars or lunar radar science: (1) The proximity of operations leads to a much higher signal to noise, as much as +30 dB. (2) The lack of an ionosphere simplifies data modeling and analysis. (3) The body is globally illuminated during every data acquisition, minimizing ambiguity or 'clutter' and allowing for tomographic reconstruction. What is novel is the data processing, where instead of a planar radargram approach we coherently process the data into an image of the deep interior. CORE thus uses a MARSIS-SHARAD heritage radar to make coherent reflection sounding measurements, a 'CAT SCAN' of a comet nucleus. What is unique about this mission compared to the Mars radars mentioned above, is that the target is a finite mass of dirty ice in free space, rather than a sheet of dirty ice draped on a planet surface. The depth of penetration (kilometers), attainable resolution (decameters), and the target materials, are more or less the same. This means that the science story is robust, and the radar implementation is robust. The target is comet 10P/Tempel 2, discovered by Wilhelm Tempel in 1873 and observed on most apparitions since. It has been extensively studied, in part because of interest as a CRAF target in the mid-1980s, and much is known about it. Tempel 2 is one of the largest known comet nuclei, 16×8×8 km (about the same size as Halley) [1] and has rotation period 8.9 hours [3,5,6,7,9]. The spin state is evolving with time, spinning up by ˜10 sec per perihelion pass [5,7]. The comet is active, but not exceedingly so, especially given its size. The water production is measured at ˜ 4 × 1028 mol/sec at its peak [2], a factor of 25 lower than comet Halley, and it is active over only ˜2% of its surface. The dust environment is well known, producing a factor of ˜100 less dust than Halley. Comet References: [1] A'Hearn et al., ApJ 347, 1155, 1989 [2] Feldman and Festou, ACM 1991, p. 171, 1992 [3] Jewitt and Luu, AJ 97, 1766, 1989 [4] Lamy et al., Comets II p 223. 2009 [5] Muel

Farnham, Tony; Asphaug, Erik; Barucci, Antonella; Belton, Mike; Bockelee-Morvan, Dominique; Brownlee, Donald; Capria, Maria Teresa; Carter, Lynn; Chesley, Steve; Farnham, Tony; Gaskell, Robert; Gim, Young; Heggy, Essam; Herique, Alain; Klaasen, Ken; Kofman, Wlodek; Kreslavsky, Misha; Lisse, Casey; Orosei, Roberto; Plaut, Jeff; Scheeres, Dan

291

The Italian involvement in Cassini radar  

NASA Astrophysics Data System (ADS)

The Radio Frequency Electronic Subsystem (RFES) of the Cassini radar is described. The requirements of the Cassini radar are summarized. The design parameters taken into consideration in developing the RFES are described. The RFES interfaces with the High Gain Antenna (HGA) for signal transmission and reception. The operational parameters of the Cassini radar are presented. The front end electronics (FEE), microwave receiver (MR), high power amplifier (HPA), frequency generator (FG), digital chip generator (DCG), Chirp Up Converter and Amplifier (CUCA) and power supply of the RFES are described.

Nirchio, F.; Pernice, B.; Borgarelli, L.; Dionisio, C.

1991-12-01

292

Thermionic converter emitter support arrangement  

DOEpatents

A support is provided for use in a therminonic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housing, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.

Allen, Daniel T. (La Jolla, CA)

1990-01-01

293

Thermionic converter emitter support arrangement  

DOEpatents

A support is provided for use in a thermionic converter to support an end an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially at its temperatures changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housng, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.

Allen, Daniel T. (La Jolla, CA)

1990-01-01

294

Emittance concept and growth mechanisms  

SciTech Connect

The authors present an introduction to the subjects of emittance and space-charge effects in charged-particle beams. This is followed by a discussion of three important topics that are at the frontier of this field. The first is a simple model, describing space-charge-induced emittance growth, which yields scaling formulas and some physical explanations for some of the surprising results. The second is a discussion of beam halo, an introduction to the particle-core model, and a brief summary of its results. The third topic is an introduction to the hypothesis of equipartitioning for collisionless particle beams.

Wangler, T.P. [Los Alamos National Lab., NM (United States). Accelerator Operations and Technology Div.

1996-05-01

295

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

296

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

297

Soviet oceanographic synthetic aperture radar (SAR) research  

SciTech Connect

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

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

1991-01-01

298

Features of ultrawideband radar projecting  

Microsoft Academic Search

The article presents a new approach to ultrawideband (UWB) radar projecting. Some advantages of such radars are shown in comparison with common narrowband radars and some features of UWB radars are considered, which do not allow the use of traditional methods. New methods of UWB radar characteristics calculation and radar systems projecting are suggested. It discusses the range equation, passive

Igor Immoreev; B. Vovshin

1995-01-01

299

Systolic architectures for radar CFAR detectors  

Microsoft Academic Search

The authors discuss several advances in the evolution of radar CFAR (constant false alarm rate) detectors, from the classical mean-level detector to more recent designs using order statistics, or sorted data values. These algorithms can be implemented by modifying the existing running window order statistic filtering techniques used in signal\\/image processing. Although the signal processing theory of CFAR detection is

Jenq-Neng Hwang; James A. Ritcey

1991-01-01

300

A microwave radio for Doppler radar sensing of vital signs  

Microsoft Academic Search

A microwave radio for Doppler radar sensing of vital signs is described. This radio was developed using custom DCS1800\\/PCS1900 base station RFICs. It transmits a single tone signal, demodulates the reflected signal, and outputs a baseband signal. If the object that reflects the signal has periodic motion, the magnitude of the baseband output signal is directly proportional to the periodic

Amy Droitcour; Victor Lubecke; Jenshan Lin; Olga Boric-Lubecke

2001-01-01

301

Radar resource sharing study  

NASA Astrophysics Data System (ADS)

The Radar Resource Sharing Study was undertaken to evaluate the relative advantages or three candidate technologies for implementing a shared beamformer for a dual band (S and UHF) airborne surveillance radar. The beamformer was required to interface with the two active array apertures and perform the signal combining and distribution functions necessary to produce the receive and transmit beams required for each band. The objective was to compare the three approaches in terms of size, weight, power consumption and hardware sharing, based on 1997 technology projections. The candidate beam-former technologies investigated were Conventional, Digital and Optical beamformers. In the digital and optical cases, technology limitations precluded accomplishing all of the required beamformer functions. Therefore, hybrid approaches which employed each of these technologies to the maximum practical extent were devised. The study commenced in September 1992 and was conducted primarily on the basis of beamformer requirements for monostatic operation. Later the scope was expanded to consider a bistatic receive implementation having significantly different beam requirements.

Gouse, Ronald; Clancy, John

1995-03-01

302

Radar applications of 10-GHZ fiber optic links  

NASA Astrophysics Data System (ADS)

Long delay lines can improve the performance and flexibility of radar test sets. A 2.25-km-long fiber optic link is used to demonstrate generation of an ideal target for a radar repeater test set and measurement of phase noise closer than 100 Hz to a 9.6-GHz radar carrier signal using a delay line discriminator phase-noise test set.

Newberg, I. L.; Gee, C. M.; Thurmond, G. D.; Yen, H. W.

1988-09-01

303

SOME RADAR TOPICS: WAVEFORM DESIGN, RANGE CFAR AND TARGET RECOGNITION  

Microsoft Academic Search

The first RADAR patent was applied for by Christian Huelsmeyer on April 30, 1904 at the patent office in Berlin, Germany.\\u000a He was motivated by a ship accident on the river Weser and called his experimental system “Telemobiloscope”. In this chapter\\u000a some important and modern topics in radar system design and radar signal processing will be discussed. Waveform design is

H. Rohling

304

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

305

Emittance of investment casting molds  

SciTech Connect

This document describes measurements of the directional spectral emittance of four ceramic mold materials. The work was performed with the samples at {approximately} 900{degree}C in a vacuum vessel pumped to {approximately}3 {times} 10{sup {minus}6}Torr. Results conform to expectations derived from prior work done with similar samples.

Havstad, M.A.

1994-07-15

306

Goldstone Solar System Radar.  

National Technical Information Service (NTIS)

Planning, direction, experimental design, and coordination of data-acquisition and engineering activities in support of all Goldstone planetary radar astronomy were performed. This work demands familiarity with the various components of a planetary radar ...

R. F. Jurgens

1988-01-01

307

Radar Absorbing Material Design.  

National Technical Information Service (NTIS)

Low observable platforms have extremely low radar cross section specifications that cannot be achieved by shaping alone. The application of radar absorbing material is necessary, in which case the appropriate constitutive parameters and thickness must be ...

C. K. Yuzcelik

2003-01-01

308

Radar, Target and Ranging.  

National Technical Information Service (NTIS)

This Test Operations Procedure (TOP) provides conventional test methods employing conventional test instrumentation for testing conventional radars. Single tests and subtests designed to test radar components, transmitters, receivers, antennas, etc., and ...

1984-01-01

309

Spaceborne Radar Study.  

National Technical Information Service (NTIS)

Three air-defense radar surveillance systems are described, each consisting of active radar satellites capable of operating at earth-synchronous orbit altitude with associated ground control stations. Systems 1 (three satellites) provides a detection fenc...

J. Greene R. Kaplan G. J. McNiff P. Nosal J. L. Schultz

1974-01-01

310

Pedestrian recognition using automotive radar sensors  

NASA Astrophysics Data System (ADS)

The application of modern series production automotive radar sensors to pedestrian recognition is an important topic in research on future driver assistance systems. The aim of this paper is to understand the potential and limits of such sensors in pedestrian recognition. This knowledge could be used to develop next generation radar sensors with improved pedestrian recognition capabilities. A new raw radar data signal processing algorithm is proposed that allows deep insights into the object classification process. The impact of raw radar data properties can be directly observed in every layer of the classification system by avoiding machine learning and tracking. This gives information on the limiting factors of raw radar data in terms of classification decision making. To accomplish the very challenging distinction between pedestrians and static objects, five significant and stable object features from the spatial distribution and Doppler information are found. Experimental results with data from a 77 GHz automotive radar sensor show that over 95% of pedestrians can be classified correctly under optimal conditions, which is compareable to modern machine learning systems. The impact of the pedestrian's direction of movement, occlusion, antenna beam elevation angle, linear vehicle movement, and other factors are investigated and discussed. The results show that under real life conditions, radar only based pedestrian recognition is limited due to insufficient Doppler frequency and spatial resolution as well as antenna side lobe effects.

Bartsch, A.; Fitzek, F.; Rasshofer, R. H.

2012-09-01

311

Applications of high-frequency radar  

NASA Astrophysics Data System (ADS)

Efforts to extend radar range by an order of magnitude with use of the ionosphere as a virtual mirror started after the end of World War II. A number of HF radar programs were pursued, with long-range nuclear burst and missile launch detection demonstrated by 1956. Successful east coast radar aircraft detect and track tests extending across the Atlantic were conducted by 1961. The major obstacles to success, the large target-to-clutter ratio and low signal-to-noise ratio, were overcome with matched filter Doppler processing. To search the areas that a 2000 nautical mile (3700 km) radar can reach, very complex and high dynamic range processing is required. The spectacular advances in digital processing technology have made truly wide-area surveillance possible. Use of the surface attached wave over the oceans can enable HF radar to obtain modest extension of range beyond the horizon. The decameter wavelengths used by both skywave and surface wave radars require large physical antenna apertures, but they have unique capabilities for air and surface targets, many of which are of resonant scattering dimensions. Resonant scattering from the ocean permits sea state and direction estimation. Military and commercial applications of HF radar are in their infancy.

Headrick, J. M.; Thomason, J. F.

1998-07-01

312

Emittance measurements at the TTF photoinjector  

Microsoft Academic Search

The TTF free electron laser requires high current electron bunches with small emittances. The beam is produced by an injector based on a laser driven RF gun. The design aims for a bunch charge of 1 nC, a bunch length in the mm range, and a normalized transverse emittance approaching 1 mm mrad. Emittance measurements in the photoinjector after preacceleration

P. Piot; S. Schreiber; D. Sertore; K. Flottmann; A. Cianchi; L. Catani

2001-01-01

313

Screen printed boron emitters for solar cells  

Microsoft Academic Search

Screen printed (SP) boron emitters are presented as a useful option for the manufacturing of p-type emitters of solar cells. Details are provided on the diffusion process, including deposition, drying and firing steps, the latter performed in an infrared belt furnace. Besides their main dependences on the firing conditions, the sheet resistances and dopant profiles of the resulting emitters reveal

F. Recart; I. Freire; L. Pérez; R. Lago-Aurrekoetxea; J. C. Jimeno; G. Bueno

2007-01-01

314

Novel deep-blue emitting phosphorescent emitter  

Microsoft Academic Search

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

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

2005-01-01

315

CHIRP Doppler radar  

Microsoft Academic Search

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

M. Bernfeld

1984-01-01

316

Aviation weather radar  

Microsoft Academic Search

The Federal Aviation Administration has established three ground-based weather radar programs. The terminal Doppler weather radar (TDWR) and weather system processor (WSP) provide wind shear detection capability for air traffic controllers in the terminal area. These systems also reduce weather related delays. The next generation weather radar (NEXRAD) is used by the FAA to improve safety and reduce weather related

D. H. Turnbull

1995-01-01

317

Harmonic Radar Literature Harmonisk Radar - en Litteraturstudie.  

National Technical Information Service (NTIS)

A harmonic radar sends on a given frequency f sub o and receives on another frequency usually 3 f sub o. The overtone is generated on joints between the metal parts of the radar target. The generated high harmonic frequency is very weak, which is why this...

B. Jansson

1980-01-01

318

Planning of a C-band pulse Doppler radar with polarization diversity for atmospheric research in the mesoscale range  

NASA Astrophysics Data System (ADS)

A radar system was defined, suitable for research in cloud physics requiring measured values of meteorological parameters relevant to a complete model of the behavior of the observed object in space and time. This problem can be solved using remote sensing methods, especially radar measuring methods. A semimobile system, comprising computer controlled pulse Doppler radar with polarization diversity and digitized radar signal processing is recommended. The fundamental attributes of the radar system are summarized.

Schuster, H.

1981-09-01

319

Antenna induced range smearing in MST radars  

NASA Astrophysics Data System (ADS)

There is considerable interest in developing stratosphere troposphere (ST) and mesosphere stratosphere troposphere (MST) radars for higher resolution to study small-scale turbulent structures and waves. At present most ST and MST radars have resolutions of 150 meters or larger, and are not able to distinguish the thin (40 - 100 m) turbulent layers that are known to occur in the troposphere and stratosphere, and possibly in the mesosphere. However the antenna beam width and sidelobe level become important considerations for radars with superior height resolution. The objective of this paper is to point out that for radars with range resolutions of about 150 meters or less, there may be significant range smearing of the signals from mesospheric altitudes due to the finite beam width of the radar antenna. At both stratospheric and mesospheric heights the antenna sidelobe level for lear equally spaced phased arrays may also produce range aliased signals. To illustrate this effect the range smearing functions for two vertically directed antennas have been calculated, (1) an array of 32 coaxial-collinear strings each with 48 elements that simulates the vertical beam of the Poker Flat, Glaska, MST radar; and (2) a similar, but smaller, array of 16 coaxial-collinear strings each with 24 elements.

Watkins, B. J.; Johnston, P. E.

1984-12-01

320

Artificial ionospheric mirrors for radar applications  

NASA Astrophysics Data System (ADS)

Recognition of performance limitations associated with traditional skywave over-the-horizon (OTH) HF radars has led a number of investigators to propose the creation of an Artificial Ionospheric Mirror (AIM) in the upper atmosphere, in order to reflect ground-based radar signals for OTH surveillance. The AIM is produced by beaming sufficient electromagnetic power to the lower ionosphere (around 70 km) to enhance the in situ ionization level to 10(exp 7) to 10(exp 8) electrons/cu cm, thereby providing an ionized layer capable of reflecting radar frequencies of 5 to 90 MHz. A baseline AIM system concept and an associated performance evaluation are presented, based upon the relevant ionization and propagation physics and in the context of air surveillance for the cruise missile threat. Results of the subject indicate that a system using this concept would both complement and enhance the performance of the existing skywave OTH radars.

Short, Robert D.; Wallace, Tom; Stewart, Clayton V.; Lallement, Pierre; Koert, Peter

1990-10-01

321

Direct path interference suppression in bistatic system: DTV based radar  

Microsoft Academic Search

Over the past 20 years, bistatic radar has been an emerging technology. One of the major problems in continuous wave bistatic radar is the direct path interference (DPI). The reflected signal from the target is received at the background of this interference; the target would be buried under the sidelobes of the DPI in the receiver circuit. The conventional solution

Rajesh Saini; M. Cherniakov; V. Lenive

2003-01-01

322

Survey of Analog-to Digital Converters for Radar Applications.  

National Technical Information Service (NTIS)

The ever increasing speeds and dynamic ranges of modern radar signal processors require the use of state of the art Analog-to Digital Converter (ADC) technology. In fact, many radar designs are constrained by the lack of ADCs with sufficient speed and/or ...

R. C. Hicks

1991-01-01

323

Doppler radar vital signs monitoring using wavelet transform  

Microsoft Academic Search

An algorithm using wavelets is used to detect heartbeat rate from a phase modulated Doppler radar signal. It is shown that the heartbeat rate can be detected up to 1.5m from the radar in a noisy environment without the need of filtering. Also the property of wavelet transform to preserve both time and frequency information is utilized to analyze the

A. Tariq; H. G. Shiraz

2010-01-01

324

Application of inverse chirp-z transform in wideband radar  

Microsoft Academic Search

Pulse stepped frequency radar is a kind of wideband radar technique. It can obtain high range resolution by correct signal processing methods. One of most important methods is the inverse Fourier transform method. This method can realize pulse compression by the coherent sum of a series of echoes. Although the inverse Fourier transform method is very useful, the number of

Wang Yiding; Wu Yirong; Hong Jun

2001-01-01

325

Reconnaissance with ultra wideband UHF synthetic aperture radar  

Microsoft Academic Search

The author addresses the problem of detecting and identifying stationary and moving targets with foliage penetrating UHF synthetic aperture radar (SAR). The role of a target's coherent SAR signature, which varies with the radar's frequency and aspect angle, in forming the Fourier space of the SAR signal is analyzed. The resultant relationship is the basis of an algorithm which, after

MEHRDAD SOUMEKH

1995-01-01

326

Aircraft target measurements using A GSM-based passive radar  

Microsoft Academic Search

Passive radar using GSM cellular mobile communication signal had been demonstrated to be feasible for short-range moving target measurements. This paper presents some new results of aircraft measurements with enhanced performance. It is shown that the operation range of GSM-based passive radar can be substantially larger than the coverage of one normal base station cell that is allocated for mobile

Hongbo Sun; D. K. P. Tan; Yilong Lu

2008-01-01

327

Passive radar localization by time difference of arrival  

Microsoft Academic Search

A detailed analysis for the performance of TDOA based passive radar localization systems is provided. The system considered in the analyses consists of four sensors and associated receiver blocks, samplers, and signal processors. Arrival time for the radar pulses is obtained by adaptive thresholding. Cramer-Rao bounds of TOA and TDOA are obtained. The effects of the receiver bandwidth and the

A. Dersan; Y. Tanik

2002-01-01

328

Soil moisture profiles from multifrequency radar data at basin scale  

Microsoft Academic Search

Multifrequency radar data are used to investigate the possibility offered by microwave remote sensing in estimating soil moisture on bare soil fields. Surface soil moisture values obtained from the inversion of a theoretical scattering model for the MAC-Europe '91 airborne campaign are compared with sampled ground measures of soil moisture for the Virginiolo experimental catchment (Tuscany, Italy). The radar signal

O. Bolognani; M. Mancini; R. Rosso

1996-01-01

329

A new CFAR sidelobe canceler algorithm for radar  

Microsoft Academic Search

Signal or target detection is sometimes complicated by the presence of strong interference. When this interference occurs mainly in the sidelobes of the antenna pattern, a solution to this problem is realized through a sidelobe canceler (SLC) implementation. Since the false-alarm probability is a system parameter of special importance in radar, an interference-canceling technique for radar application should maintain the

ELKE J. HENDON; IRVING S. REED

1990-01-01

330

Radar modelling to improve CFAR performance in the littoral  

Microsoft Academic Search

Littoral operation of radars poses severe signal processing difficulties due to the highly stressing, inhomogeneous clutter. This report describes an initial investigation into the feasibility of utilising site specific radar modelling to provide a localized estimate of the clutter statistics which can then be used to predict the required threshold to maintain a given false alarm rate. The technique has

Bill Dawber; James Branson

2006-01-01

331

Radar imaging through cinder block walls and other periodic structures  

Microsoft Academic Search

Through-wall radar imaging is a challenging area of research due to the complex multi-layer and inhomogeneous structure of building walls. The wall distorts and attenuates the radar signal in a way that is not easy to predict, except in the most simple of cases. In this paper a general periodic model is developed and applied to the imaging algorithm. Periodic

Robert J. Burkholder; Ronald J. Marhefka; John L. Volakis

2008-01-01

332

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

333

Bistatic Radar Imaging of the Marine Environment—Part II: Simulation and Results Analysis  

Microsoft Academic Search

We present a bistatic, polarimetric, and real aperture marine radar simulator (MaRS) producing pseudoraw radar signals. The simulation takes the main elements of the environment into account (sea temperature, salinity, and wind speed). Realistic sea surfaces are generated using a two-scale model on a semideterministic basis to incorporate the presence of ship wakes. Then, the radar acquisition chain (antennas, modulation,

Andreas Arnold-Bos; Ali Khenchaf; Arnaud Martin

2007-01-01

334

The meridional thermospheric neutral wind measured by radar and optical techniques in the auroral region  

Microsoft Academic Search

The theory and results of radar and Fabry-Perot interferometer scans of meridional winds are presented. The radar data were taken from Chatinika, AK, and the interferometry from the Michigan Airglow Observatory. An analytical model accounted for the effects of atomic and molecular ions on the radar signals, which were directed at the magnetic zenith. The interferometric data were gathered at

V. B. Wickwar; J. W. Meriwether Jr.; P. B. Hays; A. F. Nagy

1984-01-01

335

Fusion of Doppler Radar and video information for automated traffic surveillance  

Microsoft Academic Search

Current Doppler radar speed measurement systems lack the ability to distinguish multiple targets within the microwave beamwidth. In this paper, a traffic surveillance system is presented that is capable of automatically monitoring vehicle speeds on roadways using sensor fusion on data acquired from a calibrated video camera and a continuous wave Doppler radar. The time-frequency resolution of the radar signal

Arunesh Roy; Nicholas Gale; Lang Hong

2009-01-01

336

Low-cost radar surveillance of inland waterways for homeland security applications  

Microsoft Academic Search

Low-cost radar systems have been developed for homeland security missions. These detect and track small maneuvering craft in the water. The systems consist of a conventional marine radar, a capture card that digitizes the radar signals, and a computer that processes them. We have an experimental system that can monitor western Lake Ontario. It runs in real time, with operator

P. Weber; A. Premji; T. J. Nohara; C. Krasnor

2004-01-01

337

Radar-based Integrated Rainfall Estimates (An extract from Tromel et al., 2008, submitted to Tellus)  

Microsoft Academic Search

Our analysis aim at an enhanced quality of radar derived precipitation estimates by as fully as possible exploiting the information contained in the spatial and temporal variability of the radar signals produced by the complete precipitation generating system, e.g. by a convective cell during its life span. The results presented are yet based on pseudo-radar data and rain rates of

Silke Tromel; Clemens Simmer

338

Radar imaging of equatorial F region irregularities with maximum entropy interferometry  

Microsoft Academic Search

Radar interferometry with multiple collinear antenna baselines has been performed at Jicarnarca, near Lima, Per6, and high-resolution images of plasma irregularities in equatorial spread F have been constructed from the data. The images represent the brightness distribution of the radar backscatter, which is the Fourier transform of the visibility or spatial cross correlation of the scattered radar signal on the

D. L. Hysell

1996-01-01

339

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

2007-08-16

340

Cloud and Precipitation Radar  

NASA Astrophysics Data System (ADS)

Precipitation or weather radar is an essential tool for research, diagnosis, and nowcasting of precipitation events like fronts or thunderstorms. Only with weather radar is it possible to gain insights into the three-dimensional structure of thunderstorms and to investigate processes like hail formation or tornado genesis. A number of different radar products are available to analyze the structure, dynamics and microphysics of precipitation systems. Cloud radars use short wavelengths to enable detection of small ice particles or cloud droplets. Their applications differ from weather radar as they are mostly orientated vertically, where different retrieval techniques can be applied.

Hagen, Martin; Höller, Hartmut; Schmidt, Kersten

341

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

342

A ka-band low power Doppler radar system for remote detection of cardiopulmonary motion.  

PubMed

A low power Ka-band Doppler radar that can detect human heartbeat and respiration signals is demonstrated. This radar system achieves better than 80% detection accuracy at the distance of 2-m with 16-?W transmitted power. Indirect-conversion receiver architecture is chosen to reduce the DC offset and 1/f noise that can degrade signal-to-noise ratio and detection accuracy. In addition, the radar has also demonstrated the capability of detecting acoustic signals. PMID:17281925

Xiao, Yanming; Lin, Jenshan; Boric-Lubecke, Olga; Lubecke, Victor

2005-01-01

343

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

344

RADARC HF ionospheric prediction program for OTH radar  

NASA Astrophysics Data System (ADS)

A model for predicting the performance of an over-the-horizon high frequency (HF) radar is described. The program can also be used for management of an existing radar or for HF broadcasting assessment. When the radar parameters, such as power, antenna, and frequency are given, the program predicts the signal-to-noise, ground clutter-to-noise, ionospheric spread Doppler clutter-to-noise, and received power as a function of range from the radar site. The report is intended to provide the reader with a general description of the prediction model and to show those mathematics and procedures which are upgraded from NRL Report 2226. The procedures should provide the OTH radar engineers with information to execute the program for studies or evaluation of existing or planned radars.

Lucas, D. L.; Prinson, G. S.; Headrick, J. M.; Thomason, J. F.

1993-09-01

345

Planning of a C-Band Pulse Doppler Radar with Polarization Diversity for Atmospheric Research in the Mesoscale Range.  

National Technical Information Service (NTIS)

Radar system specifications for cloud physics studies are outlined. A semimobile system, comprising computer controlled pulse Doppler radar and digitized signal processing is recommended. Design requirements arising from the need to collect data on type o...

H. Schuster

1982-01-01

346

A CFAR Circuit with Multiple Detection Cells for Automotive UWB Radars  

Microsoft Academic Search

Future high-resolution short-range automotive radar will have a higher false alarm probability than the conventional low-resolution radar has. In a high-resolution radar, the reception signal becomes sensitive to the difference between intended and unintended objects. However, automotive radars must distinguish targets from background objects that are the same order of size; it leads to an increase in the false alarm

Satoshi Takahashi

2010-01-01

347

Ice crystal properties retrieval using radar spectral polarimetric measurements within ice\\/mixed-phase clouds  

Microsoft Academic Search

In the field of atmospheric research, ground-based radar systems are often employed to study ice\\/mixed-phase cloud properties based on retrieval techniques. These techniques convert the radar signal backscattered by each bulk of ice crystals being probed within the same radar resolution volume to cloud’s microphysical characteristics. However, the size of a radar resolution volume is often too large compared to

Y. Dufournet

2010-01-01

348

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

349

FPGA controlled DDS based frequency sweep generation of high linearity for FMCW radar systems  

Microsoft Academic Search

Two significant requirements in an FMCW radar system are linearity and low phase noise. Especially in range detection applications the achievable accuracy directly depends on the linearity of the modulated radar signal. In general PLL based systems with digital generated reference signals are used to meet this requirement. In this paper an FPGA controlled DDS based signal generator for highly

Serdal Ayhan; Viet Vu-Duy; Philipp Pahl; Steffen Scherr; Michael Hubner; Jurgen Becker; Thomas Zwick

2012-01-01

350

Use of the wavelet transform for improved CFAR detection in cw radar seekers  

Microsoft Academic Search

This paper applies wavelet transform methods to the detection of continuous wave (cw) radar signals in Gaussian white noise. The method applies to radar signal processing in typical, semi-active missile systems. The usual detection procedure consists of Fourier transforming the sampled data using the FFT, performing a CFAR operation, and thresholding. However, a detection loss occurs when the signal Doppler

Stephen P. del Marco

1995-01-01

351

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

352

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

353

Single-photon Transistors Based on the Interaction of an Emitter and Surface Plasmons  

PubMed Central

A symmetrical approach is suggested (Chang DE et al. Nat Phys 3:807, 2007) to realize a single-photon transistor, where the presence (or absence) of a single incident photon in a ‘gate’ field is sufficient to allow (prevent) the propagation of a subsequent ‘signal’ photon along the nanowire, on condition that the ‘gate’ field is symmetrically incident from both sides of an emitter simultaneously. We present a scheme for single-photon transistors based on the strong emitter-surface-plasmon interaction. In this scheme, coherent absorption of an incoming ‘gate’ photon incident along a nanotip by an emitter located near the tip of the nanotip results in a state flip in the emitter, which controls the subsequent propagation of a ‘signal’ photon in a nanowire perpendicular to the axis of the nanotip.

2008-01-01

354

Adaptive space-time processing for interference suppression in phased array radar systems. I. Search radar  

Microsoft Academic Search

This paper presents an adaptive technique of filtering to suppress the interference in phased array search radar systems. This interference includes noise, clutter, and jamming signals. Unlike the time processing techniques, our filtering process is based upon the target Doppler shift as well as the interference spatial distribution to suppress adaptively the undesired signals. This can be achieved by estimating

H. H. M. Ghouz; F. I. A. Elghany; M. M. Qutb

2000-01-01

355

Emittance of a field emission electron source  

NASA Astrophysics Data System (ADS)

An analytical formula of the emittance of a field emitter is given. In contrast to thermal and photoemission, such a formula contains complexity due to the multidimensional nature of the source. A formulation of emittance is given for one- and three-dimensional (3D) field emitters. The 3D formulation makes use of the point charge model of a unit cell emitter coupled with a trajectory analysis to follow electrons to an evaluation plane where emittance is determined. The single tip theory is extended to an array and the resulting theory predicts the emittance of a Spindt-type square array of emitters 0.2 cm on a side producing 2000 A/cm2 is 23 mm mrad. Theory compares favorably with experimental measurements in the literature from ungated and gated sources. The impacts of several complications are estimated: the effects of a gate for modulating the emitter; the influence of space charge within the unit cell on the beam; and constraints imposed by modulation frequency, emitter dimensions, and rise/fall time requirements for turning a beam on and off, as determined by the array's RLC characterization.

Jensen, K. L.; O'Shea, P. G.; Feldman, D. W.; Shaw, J. L.

2010-01-01

356

Basic characteristics of FM-CW radar systems  

NASA Astrophysics Data System (ADS)

Due to rapid technological progress in real-time signal processing, FM-CW radar systems are expected to become a more serious competitor to pulse radar systems. This paper deals with basic radar principles such as modulating waveforms and ambiguity functions characteristics. Advantages and disadvantages of FM-CW radar systems are compared to pulse radar systems. The inherent signal processing used in FM-CW radar systems allows a flexible choice of system parameters. In this context aspects like sensitivity, range and velocity resolution are discussed. It is elucidated that the use of digital processors for signal processing (frequency determination, filtering, etc.) offers the possibility to exchange dedicated hardware solutions with software implementations. Attention is paid to equipment like the antennas, diplexer, transmitter and receiver, and to isolation problems between transmitter and receiver. Results of an experimental FM-CW research radar are shown. In addition, the future prospects of FM-CW radar, with the aerial and solid-state R.F. head-end integrated, are indicated.

Ligthart, L. P.; Nieuwkerk, L. R.; Vansinttruyen, J. S.

1986-07-01

357

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

358

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

359

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

360

CCD Signal Processor Study.  

National Technical Information Service (NTIS)

This report presents the results of a study of the application of charge coupled devices (CCD's) to radar signal processing systems. The particular radar problem considered was the detection of satellites at ranges of up to 25,000 NM. A CCD baseline desig...

L. W. Martinson B. P. Gaffney G. J. Mayer

1977-01-01

361

Quantification of Reflection Patterns in Ground-Penetrating Radar Data  

NASA Astrophysics Data System (ADS)

Radar facies analysis provides a way of interpreting the large-scale structure of the subsurface from ground-penetrating radar (GPR) data. Radar facies are often distinguished from each other by the presence of patterns, such as flat-lying, dipping, or chaotic reflections, in different regions of a radar image. When these patterns can be associated with radar facies in a repeated and predictable manner we refer to them as `radar textures'. While it is often possible to qualitatively differentiate between radar textures visually, pattern recognition tools, like neural networks, require a quantitative measure to discriminate between them. We investigate whether currently available tools, such as instantaneous attributes or metrics adapted from standard texture analysis techniques, can be used to improve the classification of radar facies. To this end, we use a neural network to perform cross-validation tests that assess the efficacy of different textural measures for classifying radar facies in GPR data collected from the William River delta, Saskatchewan, Canada. We found that the highest classification accuracies (>93%) were obtained for measures of texture that preserve information about the spatial arrangement of reflections in the radar image, e.g., spatial covariance. Lower accuracy (87%) was obtained for classifications based directly on windows of amplitude data extracted from the radar image. Measures that did not account for the spatial arrangement of reflections in the image, e.g., instantaneous attributes and amplitude variance, yielded classification accuracies of less than 65%. Optimal classifications were obtained for textural measures that extracted sufficient information from the radar data to discriminate between radar facies but were insensitive to other facies specific characteristics. For example, the rotationally invariant Fourier-Mellin transform delivered better classification results than the spatial covariance because dip angle of the reflections, but not dip direction, was an important discriminator between radar facies at the William River delta. To extend the use of radar texture beyond the identification of radar facies to sedimentary facies we are investigating how sedimentary features are encoded in GPR data at Borden, Ontario, Canada. At this site, we have collected extensive sedimentary and hydrologic data over the area imaged by GPR. Analysis of this data coupled with synthetic modeling of the radar signal has allowed us to develop insight into the generation of radar texture in complex geologic environments.

Moysey, S.; Knight, R. J.; Jol, H. M.; Allen-King, R. M.; Gaylord, D. R.

2005-12-01

362

Millimeter Wave Polarimetric Monopulse Radar Debugging System  

Microsoft Academic Search

For testing millimeter wave polarimetric monopulse radar and testing algorithms for polarimetric radar, millimeter wave polarimetric monopulse radar debugging system is proposed in this paper. Polarimetric radar, as a kind of radar with strong counter-countermeasure capability, is more and more popular used nowadays. The cost of polarimetric radar is more expensive than traditional single-polarimetric radar. Millimeter wave polarimetric monopulse radar

Jin Tao; Qi Xiaohui; Zhang Min; Qiao Xiaolin; Yuan Shuqing; Zhang Qunxing

2007-01-01

363

Detecting concussion impairment with radar using gait analysis techniques  

Microsoft Academic Search

Several studies have shown that measuring changes in gait could provide an easier method of diagnosing and monitoring concussions. The purpose of this study was to measure radar signal returns to explore if differences in gait patterns between normal and \\

Jennifer W. Palmer; Kristin F. Bing; Amy C. Sharma; Eugene F. Greneker

2011-01-01

364

33 CFR 118.120 - Radar reflectors and racons.  

Code of Federal Regulations, 2013 CFR

...120 Section 118.120 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.120 Radar reflectors and racons. The District Commander may require or authorize...

2013-07-01

365

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

366

Radar in transition  

NASA Astrophysics Data System (ADS)

It is pointed out that radar engineers, at the end of 1984, find their field in transition between the conventional designs of the post War II era and the digitally controlled, solid-state systems which will be in place for the year 2000. The U.S. Navy has two major phased array radar systems in operation, including the rotating three-dimensional (3D) AN/SPS-48, and the phased-scanned AN/SPY-1 (Aegis) radars. The Aegis represents a major step beyond the conventional 3D and mechanical fire-control radars. However, it requires a special ship, dedicated to its use. Attention is given to questions regarding an extension of the application of Aegis technology to other U.S. Navy applications and to other navies, an ambitious solid-state radar program in the UK, and Army radars.

Barton, D. K.

1984-12-01

367

Review of Radar Absorbing Materials.  

National Technical Information Service (NTIS)

Radar is a sensitive detection tool and since its development, methods for reducing microwave reflections have been explored. Radar absorbers can be classified as impedance matching or resonant absorbers. Radar absorbing materials are made from resistive ...

P. Saville

2005-01-01

368

Emittance preservation in linear accelerators  

NASA Astrophysics Data System (ADS)

In linear colliders preservation of the phase space density of charged particles during acceleration to high energies is essential. In practice, the electromagnetic fields which govern the beam transport may not be sufficiently well understood. This may arise, for example, from magnet and structure alignment and/or manufacturing errors, time-varying electromagnetic fields due to component vibration or imperfect regulation, or at high beam currents, from beam-induced fields. These inadequacies may be overcome using measurements of the beam response. In this report we review such methods for preserving single-bunch beam emittances with experimental results from the Stanford Linear Collider. .

Minty, M.

2001-10-01

369

Observation and theory of the radar aurora  

SciTech Connect

Plasma density irregularities occurring near the Aurora Borealis cause scattering of HF, VHF, and UHF radio waves. Analysis of the resulting radar signal provides great detail about the spatial and temporal characteristics of these auroral E region irregularities. Observations are presented of the radar aurora from recent campaigns in northern Sweden. After reviewing the basic theory and observations of auroral electrojet irregularities, a simple nonlinear fluid theory of electrojet ion-acoustic waves is introduced, and reduced to a form of the three-wave interaction equations. This theory provides a simple mechanism for excitation of linearly stable waves at large aspect and flow angles, as well as a prediction of the power spectra that a coherent scatter radar should observe. In addition, this theory may be able to account for type 3 waves without resorting to ion gyro modes, such as the electrostatic ion-cyclotron wave. During the course of the research a simple new radar transmitting mode and signal processing algorithm was generated which very simply solves a frequency aliasing problem that often occurs in CUPRI auroral radar studies. Several new radar data analysis routines were developed, including the principally cross-beam image and scatter plots of the second versus first moments of the power spectrum of the irregularities. Analysis of vertical interferometer data shows that type 3 waves originate at ordinary electrojet altitudes, not in the upper E region, from which it is concluded that the electrostatic ion-cyclotron mode does not generate type 3 waves. The measured height of type 3 waves and other spectral analyses provide support for the pure ion-acoustic theory of type 3 waves. Suggestions are offered for hardware improvements to the CUPRI radar, new experiments to test new and existing theories.

Sahr, J.D.

1990-01-01

370

Gaussian model adaptive time domain filter (GMAT) for weather radars  

Microsoft Academic Search

This paper presents an adaptive time domain filter for ground clutter filtering and signal parameter estimation for dual-polarization capable weather radars. The auto-covariance function of radar signal can be expressed as a sum of auto-covariance functions of the clutter, precipitation and noise that follow Gaussian forms. The filter matrix is designed such as when it is applied to the time

Cuong M. Nguyen; V. Chandrasekar; Dmitri N. Moisseev

2008-01-01

371

Feasibility of STAP for passive GSM-based radar  

Microsoft Academic Search

In this paper, we examine the feasibility of applying space-time adaptive processing (STAP) to bistatic passive radars using illuminators of opportunity. The transmitters considered are GSM base stations and are non-cooperative. Although STAP has been extensively applied to signals from pulse-Doppler radars, it was never applied to arbitrary signals arising from illuminators of opportunity. We show that by computing the

Xavier Neyt; Jacques Raout; Mireille Kubica; Virginie Kubica; Serge Roques; Marc Acheroy; Jacques G. Verly

2006-01-01

372

Spaceborne Atmospheric Radar Technology  

Microsoft Academic Search

NASA is developing advanced instrument concepts and technologies for future spaceborne atmospheric radars, with the over-arching objectives of making such instruments more capable in supporting future science needs, and more cost effective. Two such examples are the Second-Generation Precipitation Radar (PR-2) and the Nexrad-In-Space (NIS). PR- 2 is a 14\\/35-GHz dual-frequency rain radar with a deployable 5- meter, wide-swath scanned

Eastwood Im; Stephen L. Durden

373

The adaptive suppression of interference in HF ground wave radar  

NASA Astrophysics Data System (ADS)

The feasibility of the concept of interference suppression in the high-frequency ground wave radar using adaptive null steering in polarization space is demonstrated. The described system uses a horizontal auxiliary aerial that feeds a least mean squares estimation filter to generate an estimate of the interference affecting the radar's performance. Subtraction of this estimate from the affected radar signal results in suppression of the interference. Skywave interference-to-noise levels were reduced by up to 30 dB. The performance depends upon there being a detectable horizontal component of the interference signal's polarization.

Madden, J. M.

374

Directional emittance corrections for thermal infrared imaging  

NASA Astrophysics Data System (ADS)

A simple measurement technique for measuring the variation of directional emittance of surfaces at various temperatures using commercially available radiometric IR imaging systems was developed and tested. This technique provided the integrated value of directional emittance over the spectral bandwidth of the IR imaging system. The directional emittance of flat black lacquer and red stycast, an epoxy resin, measured using this technique were in good agreement with the predictions of the electromagnetic theory. The data were also in good agreement with directional emittance data inferred from directional reflectance measurements made on a spectrophotometer.

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

1992-04-01

375

Chromatic effects in quadrupole scan emittance measurements  

NASA Astrophysics Data System (ADS)

A reliable transverse emittance measurement for high-brightness electron beams is of utmost importance for the successful development of fourth generation light sources and for the beam transport in plasma-based accelerators. When the beam exhibits a significant energy spread, typical quadrupole scan emittance measurements may be affected depending on the beam properties and on the quadrupoles arrangement. The emittance degradation induced by chromatic effects in measurements involving magnetic lattices is evaluated analytically for different configurations. Analytical and numerical calculations compared with measurements have been used to evaluate the consequent error on the emittance value measured for single and double quadrupole schemes and for typical operating conditions at the SPARC facility.

Mostacci, A.; Bellaveglia, M.; Chiadroni, E.; Cianchi, A.; Ferrario, M.; Filippetto, D.; Gatti, G.; Ronsivalle, C.

2012-08-01

376

Warning signal brightness variation: sexual selection may work under the radar of natural selection in populations of a polytypic poison frog.  

PubMed

Though theory predicts consistency of warning signals in aposematic species to facilitate predator learning, variation in these signals often occurs in nature. The strawberry poison frog Dendrobates pumilio is an exceptionally polytypic (populations are phenotypically distinct) aposematic frog exhibiting variation in warning color and brightness. In the Solarte population, males and females both respond differentially to male brightness variation. Here, we demonstrate through spectrophotometry and visual modeling that aposematic brightness variation within this population is likely visible to two putative predators (crabs, snakes) and conspecifics but not to the presumed major predator (birds). This study thus suggests that signal brightness within D. pumilio populations can be shaped by sexual selection, with limited opportunity for natural selection to influence this trait due to predator sensory constraints. Because signal brightness changes can ultimately lead to changes in hue, our findings at the within-population level can provide insights into understanding this polytypism at across-population scales. PMID:23594556

Crothers, Laura R; Cummings, Molly E

2013-02-25

377

DORIS radar calibration method  

NASA Astrophysics Data System (ADS)

Following the interest expressed by ESA and FGAN, it was decided to realise some evaluation of the DORIS calibration method with the TIRA radar. This paper, organised in four parts, describes: - the importance of radar calibration in the space debris domain - the principle of the DORIS calibration method - the results obtained with the TIRA FGAN radar using the DORIS reference - the advantages of the DORIS calibration and the future uses of this method in an European exercise involving for the ESA benefit both French and German radars.

Ameline, P.

2001-10-01

378

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

379

Interkosmos laser radar for satellite tracking  

Microsoft Academic Search

Technical specifications of the Interkosmos laser ranging radar for satellite tracking are presented. Pulse processing techniques, system calibration, stability and the effects of various parameters on the accuracy of range measurements to satellite are reviewed. The expected signal level from a satellite is presented as a function of range and the area cross section of the satellite equipped with retroreflectors,

P. S. Dixit; P. K. Rao

1980-01-01

380

Radar Soundings of the Subsurface of Mars  

Microsoft Academic Search

The martian subsurface has been probed to kilometer depths by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument aboard the Mars Express orbiter. Signals penetrate the polar layered deposits, probably imaging the base of the deposits. Data from the northern lowlands of Chryse Planitia have revealed a shallowly buried quasi-circular structure about 250 kilometers in diameter that is

Giovanni Picardi; Jeffrey J. Plaut; Daniela Biccari; Ornella Bombaci; Diego Calabrese; Marco Cartacci; Andrea Cicchetti; Stephen M. Clifford; Peter Edenhofer; William M. Farrell; Costanzo Federico; Alessandro Frigeri; Donald A. Gurnett; Tor Hagfors; Essam Heggy; Alain Herique; Richard L. Huff; Anton B. Ivanov; William T. K. Johnson; Rolando L. Jordan; Donald L. Kirchner; Wlodek Kofman; Carlton J. Leuschen; Erling Nielsen; Roberto Orosei; Elena Pettinelli; Roger J. Phillips; Dirk Plettemeier; Ali Safaeinili; Roberto Seu; Ellen R. Stofan; Giuliano Vannaroni; Thomas R. Watters; Enrico Zampolini

2005-01-01

381

Superregenerative Incoherent UWB Pulse Radar System  

Microsoft Academic Search

A new short range ultra wideband (UWB) radar system with a very simple design due to its superregenerative receiver concept has been studied. The system does not require any amplification of RF or IF signals which allows to build a very inexpensive low-power sensor. With measurements, simple mathematical models and a simulation in time-domain the voltage amplitude of the measurement

T. Wuchenauer; M. Nalezinski; W. Menzel

2006-01-01

382

Thresholded samplers for UWB impulse radar  

Microsoft Academic Search

This paper presents two novel methods for sampling the backscatter in an impulse radar system. The authors have called the two related methods for swept threshold and stochastic resonance sampling. The samplers are simple, mostly digital circuits which are not clocked, but instead utilize continuous-time signal processing. Since fine-pitch CMOS is not very good for analog processing, but instead has

Hakon A. Hjortland; Dag T. Wisland; Tor Sverre Lande; Claus Limbodal; Kjetil Meisal

2007-01-01

383

Teaching the common emitter amplifier  

NASA Astrophysics Data System (ADS)

If one wishes to teach some device electronics in schools it will have to be very limited. It is not productive to measure all the common emitter and common base characteristics of the bipolar transistor as required by at least one A-level syllabus. To do so wastes pupil time and leads to considerable confusion. Nor should the study be extended to cover for example all possible methods of biasing a common emitter amplifier. What is needed is a 'bare bones' approach, enough to give a first step towards understanding the subject. A case can be made for the study of an operational amplifier in electronic circuits, treating it as an ideal electronic 'device'. However, the author's personal feeling is that the study of a single active device such as the bipolar transistor provides a firm background from which students can extend their study of electronics and has the advantage in a physics course that from there it is a very short step to discuss a simple model for the internal mechanisms of semiconductor devices.

Ellse, Mark D.

1984-11-01

384

Evaluations of carbon nanotube field emitters for electron microscopy  

Microsoft Academic Search

Brightness of carbon nanotube (CNT) emitters was already reported elsewhere. However, brightness of electron emitter is affected by a virtual source size of the emitter, which strongly depends on electron optical configuration around the emitter. In this work, I–V characteristics and brightness of a CNT emitter are measured under a practical field emission electron gun (e-gun) configuration to investigate availability

Hitoshi Nakahara; Yoshikazu Kusano; Takumi Kono; Yahachi Saito

2009-01-01

385

Statistical study of the spectral broadening of skywave signals backscattered by the sea surface - Application to RMS wave height measurement with a skywave radar  

NASA Astrophysics Data System (ADS)

HF skywave signals backscattered by the sea surface are studied on a large set of data (more than 30 h of 64 independent signals) to identify the sources of the broadening of the first-order spectral line. Using high-quality signals reflected by sporadic E ionospheric layers, the natural broadening due to sea-scattering effects has been scaled to about 3/100 Hz. When the signals propagate via F layer, the total broadening due to ionospheric effects is similar in magnitude and can be attributed to two causes. The first, due to frequency modulation effects, which can be identified and corrected, scales on average to 1/100 Hz. The second, called unresolved ionospheric effects, scales on average to 2/100 Hz and is probably due to the spatial variation of the ionospheric Doppler within the ionospheric control volume. Since they are greatly variable with time and space, the influence of these unresolved ionospheric effects can be reduced by sorting spectra, according to the value of the equivalent spectral width, before averaging. Using such sorting and correcting the signals for the ionospheric frequency modulation, 70 percent of the considered set of data are usable to measure the root mean square (RMS) wave height.

Parent, Jacques

1989-09-01

386

A Ka-Band Low Power Doppler Radar System for Remote Detection of Cardiopulmonary Motion  

Microsoft Academic Search

A low power Ka-band Doppler radar that can detect human heartbeat and respiration signals is demonstrated. This radar system achieves better than 80% detection accuracy at the distance of 2-m with 16-muW transmitted power. Indirect-conversion receiver architecture is chosen to reduce the DC offset and 1\\/f noise that can degrade signal-to-noise ratio and detection accuracy. In addition, the radar has

Yanming Xiao; Jenshan Lin; Olga Boric-Lubecke; Victor M. Lubecke

2005-01-01

387

Multi-platform RF emitter localization using extremum seeking control  

NASA Astrophysics Data System (ADS)

In recent years there has been growing interest in Ad-hoc and Wireless Sensor Networks (WSNs) for a variety of indoor applications. 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. Position-Adaptive radar concepts have been formulated and investigated at the Air Force Research Laboratory (AFRL) within the past few years. Adopting a position-adaptive approach to the design of distributed radar systems shows potential for the development of future radar systems that function under new and challenging environments that contain large clutter discretes and require co-functionality within multi-signal RF environments. In this paper, we present the simulation performance analysis on the application aspect. We apply Extremum Seeking Control (ESC) schemes by using the swarm seeking problem, where the goal is to design a control law for each individual sensor that can minimize the error metric by adapting the sensor positions in real-time based on cross-path loss exponents estimates between sensors, thereby minimizing the unknown estimation error. As a result we achieved source seeking and collision avoidance of the entire group of the sensor positions.

Al Issa, Huthaifa; Ordóñez, Raúl

2013-05-01

388

SMAP Radar Processing and Expected Performance  

NASA Astrophysics Data System (ADS)

This presentation will describe the processing algorithms being developed for the Soil Moisture Active Passive (SMAP) radar data and the expected characteristics of the measured backscattering cross sections. The SMAP radar combines some unique features such as a conically scanned antenna with SAR processing of the data. The rapidly varying squint angle gives the measurements variable resolution and noise characteristics and poses a challenge to the processor to maintain accuracy around the wide (1000 km) swath. Rapid variation of Doppler around the scan leads to a time domain azimuth correlation algorithm, and variation of the Doppler geometry will likely require varying the processing bandwidth to manage ambiguity contamination errors. The basic accuracy requirement is 1-dB (one-sigma) in the backscatter measurements at a resolution of 3 km. The main error contributions come from speckle noise, calibration uncertainty, and radio frequency interference (RFI). Speckle noise is determined by system design parameters and details of the processing algorithms. The calibration of the backscatter measurements will be based on pre-launch characterization of the radar components which allow corrections for short term (~1 month) variations in performance. Longer term variations and biases will be removed using measurements of stable reference targets such as parts of the Amazon rain forest, and possibly the oceans and ice sheets. RFI survey measurements will be included to measure the extent of RFI around the world. The SMAP radar is designed to be able to hop the operating frequency within the 80 MHz allocated band to avoid the worst RFI emitters. Data processing will detect and discard further RFI contaminated measurements. This work is supported by the SMAP project at JPL - CalTech. The SMAP mission has not been formally approved by NASA. The decision to proceed with the mission will not occur until the completion of the National Environmental Policy Act (NEPA) process. Material in this document related to SMAP is for information purposes only.

West, R. D.; Jaruwatanadilok, S.

2011-12-01

389

A Theory of Radar Reflection from the Moon and Planets  

Microsoft Academic Search

Huygens' principle is used to derive relations between the surface statistics of a randomly irregular celestial radar target and the angular power spectrum and autocorrelation function of the reflected signal. The spatial correlation function of the signal observed by spaced receivers is also computed. From observed lunar signal fading data a crude pictorial representation of the small-scale structure of the

Fred B. Daniels

1961-01-01

390

EISCAT Svalbard radar  

Microsoft Academic Search

The main fields of interest of the Finnish scientists in EISCAT research are listed. Finnish interests in the Polar Cap Radar (PMR) and areas where the Finnish contribution could be important are addressed: radar techniques; sporadic E layers in the polar cap; atmospheric models; auroral studies in the polar cap; nonthermal plasmas in the F region; coordinated measurements with the

Markku Lehtinen; Jorma Kangas

1992-01-01

391

EISCAT Svalbard Radar.  

National Technical Information Service (NTIS)

The main fields of interest of the Finnish scientists in EISCAT research are listed. Finnish interests in the Polar Cap Radar (PMR) and areas where the Finnish contribution could be important are addressed: radar techniques; sporadic E layers in the polar...

M. Lehtinen J. Kangas

1992-01-01

392

Radar illusion via metamaterials  

NASA Astrophysics Data System (ADS)

An optical illusion is an image of a real target perceived by the eye that is deceptive or misleading due to a physiological illusion or a specific visual trick. The recently developed metamaterials provide efficient approaches to generate a perfect optical illusion. However, all existing research on metamaterial illusions has been limited to theory and numerical simulations. Here, we propose the concept of a radar illusion, which can make the electromagnetic (EM) image of a target gathered by radar look like a different target, and we realize a radar illusion device experimentally to change the radar image of a metallic target into a dielectric target with predesigned size and material parameters. It is well known that the radar signatures of metallic and dielectric objects are significantly different. However, when a metallic target is enclosed by the proposed illusion device, its EM scattering characteristics will be identical to that of a predesigned dielectric object under the illumination of radar waves. Such an illusion device will confuse the radar, and hence the real EM properties of the metallic target cannot be perceived. We designed and fabricated the radar illusion device using artificial metamaterials in the microwave frequency, and good illusion performances are observed in the experimental results.

Jiang, Wei Xiang; Cui, Tie Jun

2011-02-01

393

Advances in Radar Techniques  

NASA Astrophysics Data System (ADS)

Most of the clutter received by L, S, C, X, and Ku band radars obeys a Weibull ditribution. To suppress such Weibull-distributed sea and weather clutter, Weibull CFAR techniques are applied to data taken by an X-band radar using computer in real time. The results show the usefulness of Weibull CFAR.

Sekine, Matsuo

394

UWB radars in medicine  

Microsoft Academic Search

Applied research on biomedical applications of UWB radar is targeted to the identification of the possible new devices made possible by the technology, to the design and development of those devices, and to the clinical testing of the systems obtained. Applications can be divided into two main sectors according to the frequency range used. For the conventional UWB radar microwave

Enrico M. Staderini

2002-01-01

395

Stereo Radar Analysis.  

National Technical Information Service (NTIS)

The topographic accuracy of the AN/APQ-102(XA-2) side-looking radar and its specific applicability to 1:50,000 and 1:250,000 scale topographic mapping were tested using stereo radar techniques with real data. The two basic stereo configurations, opposite-...

G. Gracie R. K. Brewer J. W. Bricker R. A. Johnson

1970-01-01

396

Panchromatic and polypanchromatic radar  

Microsoft Academic Search

Application of broad-band (panchromatic) illumination in radar systems should permit improvement in image quality and reduction of tracking and detection problems due to fading. The effect of frequency averaging on radar return from a simple target array is demonstrated by numerical computation and on image quality by ultrasonic simulation. The required bandwidth for a slightly rough random surface is determined

RICHARD K. MOORE; WILLIAM P. WAITE

1969-01-01

397

Radar clutter classification  

Microsoft Academic Search

The problem of classifying radar clutter as found on air traffic control radar systems is studied, and an algorithm is developed to carry out this classification automatically. The basis for the algorithm is Bayes decision theory and the parametric maximum a posteriori probability (MAP) classifier. This classifier employs a quadratic discriminant function and is optimum for feature vectors that are

Wolfgang Stehwien

1990-01-01

398

Radar clutter classification  

Microsoft Academic Search

The problem of classifying radar clutter as found on air traffic control radar systems is studied. An algorithm based on Bayes decision theory and the parametric maximum a posteriori probability classifier is developed to perform this classification automatically. This classifier employs a quadratic discriminant function and is optimum for feature vectors that are distributed according to the multivariate normal density.

Wolfgang Stehwien

1989-01-01

399

An electron gun with a plasma emitter  

SciTech Connect

This paper describes a continuous-running electron gun which has a plasma emitter that is based on a reflective arc discharge in a cold hollow cathode, which provides an electron beam carrying a current of 1 A. The beam current can be regulated smoothly from 1 mA to 1 A by varying the potential of the emitter cathode.

Gruzdev, V.A.; Kreindel', Y.E.; Rempe, N.G.; Troyan, O.E.

1985-01-01

400

SINGLE BUNCH EMITTANCE PRESERVATION IN XFEL LINAC  

Microsoft Academic Search

The single bunch emittance preservation in booster and main linacs of European XFEL project is presented. The wakefield and chromatic dilution of the beam emittance caused by free betatron oscillations, cavity and modules offset misalignments and random tilts are evaluated. The effects of cavities misalignments correlation along the linac are discussed. The effects of quadrupole misalignments and the corresponding trajectory

G. Amatuni; V. Tsakanov; Armenia W. Decking; R Brinkmann

2006-01-01

401

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

402

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

403

On radar polarimetry in FM-CW radar  

Microsoft Academic Search

This paper attempts to apply the principle of radar polarimetry to wideband synthetic aperture FM-CW radar and presents a basic polarimetric detection result of a linear target in a laboratory measurement. Although the principle of radar polarimetry has well been established for the completely polarized wave and for the monostatic case, it still needs to be extended to wideband radar

Y. Yamaguchi; T. Nishikawa; W.-M. Boerner; M. Sengoku; Hyo Joon Eom

1993-01-01

404

Electrospray Ionization from Nanopipette Emitters with Tip Diameters of Less than 100 nm.  

PubMed

Work presented here demonstrates application of nanopipettes pulled to orifice diameters of less than 100 nm as electrospray ionization emitters for mass spectrometry. Mass spectrometric analysis of a series of peptides and proteins electrosprayed from pulled-quartz capillary nanopipette emitters with internal diameters ranging from 37 to 70 nm is detailed. Overall, the use of nanopipette emitters causes a shift toward the production of ions of higher charge states and leads to a reduction in width of charge-state distribution as compared to typical nanospray conditions. Further, nanopipettes show improved S/N and the same signal precision as typical nanospray, despite the much smaller dimensions. As characterized by SEM images acquired before and after spray, nanopipettes are shown to be robust under conditions employed. Analytical calculations and numerical simulations are used to calculate the electric field at the emitter tip, which can be significant for the small diameter tips used. PMID:23968307

Yuill, Elizabeth M; Sa, Niya; Ray, Steven J; Hieftje, Gary M; Baker, Lane A

2013-08-28

405

TPV Systems with Solar Powered Tungsten Emitters  

NASA Astrophysics Data System (ADS)

A solar TPV generator development and characterization are presented. A double stage sunlight concentrator ensures 4600x concentration ratio. TPV modules based on tungsten emitters and GaSb cells were designed, fabricated and tested at indoor and outdoor conditions. The performance of tungsten emitter under concentrated solar radiation was analyzed. Emitter temperatures in the range of 1400-2000 K were measured, depending on the emitter size. The light distribution in the module has been characterized, 1×1 cm GaSb TPV cells were fabricated with the use of the Zn-diffusion and LPE technologies. The cell efficiency of 19% under illumination by a tungsten emitter (27% under spectra cut-off at ? > 1820 nm) heated up to 1900-2000 K had been derived from experimentally measured PV parameters. The series connection of PV cells was ensured by the use of BeO ceramics. The possibilities of system performance improvement are discussed.

Vlasov, A. S.; Khvostikov, V. P.; Khvostikova, O. A.; Gazaryan, P. Y.; Sorokina, S. V.; Andreev, V. M.

2007-02-01

406

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

407

Measurement of electromagnetic fields generated by air traffic control radar systems with spectrum analysers.  

PubMed

Air traffic control (ATC) primary radars are 'classical' radars that use echoes of radiofrequency (RF) pulses from aircraft to determine their position. High-power RF pulses radiated from radar antennas may produce high electromagnetic field levels in the surrounding area. Measurement of electromagnetic fields produced by RF-pulsed radar by means of a swept-tuned spectrum analyser are investigated here. Measurements have been carried out both in the laboratory and in situ on signals generated by an ATC primary radar. PMID:19864331

Barellini, A; Bogi, L; Licitra, G; Silvi, A M; Zari, A

2009-10-28

408

Capillary-Based Multi Nanoelectrospray Emitters: Improvements in Ion Transmission Efficiency and Implementation with Capillary Reversed-Phase LC-ESI-MS  

SciTech Connect

We describe the coupling of liquid chromatography (LC) separations with mass spectrometry (MS) using nanoelectrospray ionization (nanoESI) multi-emitters. The array of 19 emitters reduced the flow rate delivered to each emitter, allowing the enhanced sensitivity that is characteristic of nanoESI to be extended to higher flow rate separations. The signal for peptides from spiked proteins in a human plasma tryptic digest increased 11-fold on average when the multi-emitters were employed, due to increased ionization efficiency and improved ion transfer efficiency through a newly designed heated multi-capillary MS inlet. Additionally, the LC peak signal-to-noise ratio increased ~7-fold when the multi-emitter configuration was used. The low dead volume of the emitter arrays preserved peak shape and resolution for robust capillary LC separations using total flow rates of 2-µL/min.

Kelly, Ryan T.; Page, Jason S.; Zhao, Rui; Qian, Weijun; Mottaz, Heather M.; Tang, Keqi; Smith, Richard D.

2008-01-01

409

Phased-array radar for airborne systems  

NASA Astrophysics Data System (ADS)

Phased array antenna systems, which support high pulse rates and high transmit power, are well suited for radar and large-scale surveillance. Sensors and communication systems can function as the eyes and ears for ballistic missile defense applications, providing early warning of attack, target detection and identification, target tracking, and countermeasure decision. In such applications, active array radar systems that contain solid-state transmitter sources and low-noise preamplifiers for transmission and reception are preferred over the conventional radar antennas, because the phased array radar offers the advantages of power management and efficiency, reliability, signal reception, beam steering target detection. The current phased array radar designs are very large, complex and expensive and less efficient because of high RF losses in the phase control circuits used for beam scan. Several thousands of phase shifters and drivers may be required for a single system thus making the system very complex and expensive. This paper describes the phased array radar system based on high power T/R modules, wide-band radiating planar antenna elements and very low loss wide-band phase control circuits (requiring reduced power levels) for beam scan. The phase shifter design is based on micro-strip feed lines perturbed by the proximity of voltage controlled piezoelectric transducer (PET). Measured results have shown an added insertion loss of less than 1 dB for a phase shift of 450 degrees from 2 to 20 GHz. The new wideband phased array radar design provides significant reduction in size cost and weight. Compared to the conventional phased array systems, the cost saving is more than 15 to 1.

Tahim, Raghbir S.; Foshee, James J.; Chang, Kai

2003-09-01

410

Low emittance electron beam studies  

NASA Astrophysics Data System (ADS)

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*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

411

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

412

An experimental adaptive radar array system  

NASA Astrophysics Data System (ADS)

An experimental adaptive array incorporated in an FMCW radar system is described. An FMCW radar is relatively simple and compact. It is easy to realize high range resolution and low probability of interception, and it has many promising applications in anticollision, missile guidance, navigation, and MW imaging radars. The Gram-Schmidt adaptive algorithm was used for the system and proven quite effective. For one interference case the interference null depth was better than -38 dB and the signal-to-interference ratio improvement was better than 25 dB in the entire electronic scanning region. The present algorithm produced good nulls in the interference directions; however, it produced big sidelobes in the interference directions in some cases, especially when scanning to a large aiming angle.

Gong, Y. H.

413

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.

414

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))

1992-01-01

415

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

416

A new approach to moving terrestrial targets recognition using ground surveillance pulse doppler RADARs  

Microsoft Academic Search

In this paper we propose a new automatic target recognition algorithm to recognize and distinguish of three classes of targets: personnel, wheeled vehicles and animals, using a low-resolution ground surveillance pulse Doppler radar. Using the chirplet transformation, a time-frequency signal processing technique, the parameterized radar signal is then used by the Zernike moments (ZM) for the pertinent features of the

M. Alaee; H. Amindavar; A. M. Reza

2008-01-01

417

Design of the radar real-time simulation system joined with hardware  

Microsoft Academic Search

To improve the real-time property for typical Pulse Doppler radar simulation, an idea of signal-level simulation using hardware was proposed. The system framework and information flow was studied, then a host method of moving target echo simulation was given. Most of all, radar signal processing was realized by FPGA, which includes digital quadrature detection with IF sampling, pulse compression based

Yong Chen; Xinyu Yao; Wenbo Wu; Xiaofeng Tang

2011-01-01

418

Accurate Doppler Radar Noncontact Vital Sign Detection Using the RELAX Algorithm  

Microsoft Academic Search

We consider using a Doppler radar for accurate noncontact vital sign detection. The Doppler radar first captures and downconverts the wireless signal that is phase modulated by the physiological movements, and then identifies the human heartbeat and respiration rates by processing the baseband signal. When nonlinear Doppler phase modulation is employed to monitor vital signs without contact, one of the

Changzhi Li; Jun Ling; Jian Li; Jenshan Lin

2010-01-01

419

Reducing the effects of noise on atmospheric imaging radars using multilag correlation  

Microsoft Academic Search

Atmospheric imaging radars offer the capability to scrutinize structures within the illuminated volume at high temporal and spatial resolutions. The retrieval of the mean signal power using an imaging radar is obtained by subtracting the noise power from the covariance function at lag zero. The results obtained at low signal-to-noise ratio (SNR) are problematic when the noise power is unsuccessfully

K. D. Le; R. D. Palmer; B. L. Cheong; T.-Y. Yu; G. Zhang; S. M. Torres

2010-01-01

420

Electron density profiles in the equatorial E region ionosphere derived from a bistatic coherent scatter radar experiment in Perú  

Microsoft Academic Search

A new bistatic radar system has been developed at the Jicamarca Radio Observatory. The system is a permanent addition to the facility designed to monitor electron density profiles in the equatorial electrojet region using a coherent scatter radar technique that utilizes the Faraday rotation of the scattered signal. A series of radar experiments has been conducted at Jicamarca since March,

E. B. Shume; D. L. Hysell; J. L. Chau

2005-01-01

421

Observations of mesosphere summer echoes with calibrated VHF radars at latitudes between 54°N and 69°N in summer 2004  

NASA Astrophysics Data System (ADS)

Mesosphere Summer Echoes (MSE) have been observed with 50-MHz VHF radars at middle (MSE) and polar latitudes (PMSE) for more than 20 years. The occurrence and seasonal variation of these radar echoes as well as their dependence on solar and geomagnetic activity are mostly studied basing on relative signal strength measurements (signal-to-noise ratios). The latitudinal dependence of the appearance and intensity of mesospheric summer echoes is still an open question as the widely used relative signal strength observations are determined by the atmospheric properties as well as by the individual radar characteristics. The use of absolutely calibrated echo powers allows a system in-depended comparison of mesospheric summer echoes observed at different sites by different systems. We present two different radar calibration methods. One applies a noise source to calibrate the receive path of the radar only, a second uses the radar signal itself to calibrate the complete transmitting and receiving path of the radar system. Both techniques and the same calibration hardware have been applied to the ALWIN VHF radar at Andenes/Norway (69°N), the ESRAD radar at Kiruna/Sweden (68deg;N) and OSWIN radar at Kühlungsborn/Germany (54°N). The sensitivity of the different radar systems and the seasonal and diurnal variation of the occurrence of mesospheric summer echoes at different locations are discussed on the basis of radar backscatter cross-sections.

Latteck, R.; Singer, W.; Kirkwood, S.; Jönsson, L. O.; Eriksson, Håkan

2005-08-01

422

Air traffic control radar tester  

Microsoft Academic Search

Our aim is to develop a radar tester equipment for commercial and military services. The task is to create one (or more) target or clutter on the radar screen with given distance, velocity and fluctuation. This equipment is placed within few hundred meters from the radar, so it is able to analyze the whole radar system from the antenna, via

Péter KOVÁCS; Levente DUDÁS; Rudolf SELLER; József ORBÁN

2008-01-01

423

Air traffic control radar tester  

Microsoft Academic Search

Our aim had been to develop a radar tester equipment for commercial and military services. The task is to create one (or more) target or clutter on the radar screen with given distance, velocity and fluctuation. This equipment is placed within few hundred meters from the radar, so it is able to analyze the whole radar system from the antenna,

Levente DUDÁS; Rudolf SELLER; Péter RENNER; József ORBÁN

2009-01-01

424

Radar Symposium, 7th, Universitaet Ulm, Federal Republic of Germany, Oct. 10-12, 1989, Reports  

NASA Astrophysics Data System (ADS)

Various papers on radar are presented. Individual topics addressed include: aspects of long-wave radiation, future NATO identification systems, experimental X-band SAR, results of first tests of the ROSAR method, concept and results of the azimuth Quick-Look Processor for the SAR aircraft, specification of an inertial navigation system for experimental SAR, detection of slowly moving targets with airborne radar, fast method for disturbance-free two-dimensional ISAR imaging, development and optimization of a coastal radar system, determination of orientation accuracy in curving trajectories, radome structures for high-frequency applications. Also discussed are: monolithically integrated GaAs switching circuits for the millimeter wave range, new pulse compression methods for periodically phase-coded signal transmission, architectures of programmable radar signal processors, evaluation of the period length of periodic signals, interactive simulation system for multisensor systems, intelligent radar data processing, knowledge-based components of a tracking system, radar signatures of highly resolving millimeter wave sensors.

Baur, K.

425

Correlation detection filter for imaging laser radar  

NASA Astrophysics Data System (ADS)

Laser radar can simultaneously produce the intensity and range images, and the space resolution is high, so the recognition performance is well, and it can choose the aim point of target. Laser radar is applied to many fields, such as guidance, navigation, and becomes the research hot point in recent years. In the vertical detection of laser radar, the algorithm is required not only solving in-plane rotation-invariant problem, also the distortion-invariant problem, and it must satisfied the real-time. Correlation algorithm is a parallel processing procedure, detecting many targets at one time, and its design can be implemented on the high speed digital signal processor. In the paper, a new filter named CHF-MACH filter is presented, which combine multiple circular harmonic expansions into one filter through MACH criteria. Because of the filter having the characters of the two filters, it can solve the problems of in-plane rotation-invariance and distortion-invariance simultaneously, and meet the real-time requirement. The simulated range image of laser radar is regarded as research target, and computing the PSR (peak to sidelobe ratio) values of correlation output of the different objects, and plotting the PSR curves of the different angles. Simulating the scene of laser radar which includes multiple objects, CHF-MACH filter performance is validated through testing with the different angles for the objects, and the non-training images can obtain the well correlation output.

Sun, Jianfeng; Li, Qi; Lu, Wei; Wang, Qi

2007-01-01

426

Rendezvous radar for the orbital maneuvering vehicle  

NASA Astrophysics Data System (ADS)

This paper describes the development of the Rendezvous Radar Set (RRS) for the Orbital Maneuvering Vehicle (OMV) for the National Aeronautics and Space Administration (NASA). The RRS was to be used to locate, and then provide vectoring information to, target satellites (or Shuttle or Space Station) to aid the OMV in making a minimum-fuel-consumption approach and rendezvous. The RRS design is that of an X-Band, all solid-state, monopulse tracking, frequency hopping, pulse-Doppler radar system. The development of the radar was terminated when the OMV prime contract to TRW was terminated by NASA. At the time of the termination, the development was in the circuit design stage. The system design was virtually completed, the PDR had been held. The RRS design was based on Motorola's experiences, both in the design and production of radar systems for the US Army and in the design and production of hi-rel communications systems for NASA space programs. Experience in these fields was combined with the latest digital signal processor and micro-processor technology to design a light-weight, low-power, spaceborne radar. The antenna and antenna positioner (gimbals) technology developed for the RRS is now being used in the satellite-to-satellite communication link design for Motorola's Iridium telecommunications system.

Locke, John W.; Olds, Keith; Parks, Howard

427

Direction synthesis in DOA estimation for monostatic multiple input multiple output (MIMO) radar based on synthetic impulse and aperture radar (SIAR) and its performance analysis  

Microsoft Academic Search

A new direction synthetic method for monostatic multiple input multiple output (MIMO) radar is presented based on synthetic\\u000a impulse and aperture radar (SIAR) system. Concerned with the monostatic MIMO radar which simultaneously emits orthogonal signals\\u000a with multi-carrier-frequency and possesses sparsely distributed transmitting and receiving arrays with respective location,\\u000a as well as the situation for the presence of multipath propagation in

GuangHui Zhao; BaiXiao Chen; ShouPing Zhu

2008-01-01

428

DURIP instrumentation support for high-latitude ionospheric research and the establishment of a dual radar\\/dual frequency observational capability at the Millstone Radar Facility  

Microsoft Academic Search

Radar receiver and signal processing instrumentation was acquired and fabricated in order to establish a capability for dual 440 MHz and 1390 MHz radar operations at the M.I.T. Millstone Hill research facility. Hardware costs for a duplicate of the MIDAS radar processor were provided. This instrumentation enables a program of simultaneous, high-spatial resolution dual frequency observations of non-thermal and coherent

John C. Foster

1991-01-01

429

Contribution aux etudes de signaux radar de surfaces de mer et mise au point d'un traitement rapide  

Microsoft Academic Search

Dans le but d'utiliser un radar comme instrument de mesures oceanographiques, il apparai t necessaire de developper des techniques pour extraire les caracteristiques d'une surface de mer a partir du signal recu par le radar. La plupart des algorithmes existant considerent les images radar comme des photographies de la surface oceanique, negligeant l'effet de la vitesse de rotation du radar

Anne-Laure Jousselme

1997-01-01

430

Improvement of X-band radar rainfall estimates using a microwave link  

NASA Astrophysics Data System (ADS)

In recent years the significance of highly resolved rainfall information in space and time for hydrological applications increased steadily. Weather radar systems provide this information but the derivation of quantitatively reliable radar rainfall estimates is still known to be problematic. The attenuation of the radar signal by rainfall has been identified as crucial and especially X-band radars are affected by this phenomenon. The current methods of correcting for attenuation face many problems, mainly because the actual amount of attenuation is unknown. In this paper attenuation and rainfall information derived from a microwave link are used as a reference to correct an X-band radar for rainfall. A microwave link receiver is co-located with an X-band weather radar in Essen, Germany. Therefore, the microwave link provides path integrated attenuation and rainfall information parallel to a radar beam over a distance of 30 km. The correction of radar rainfall is done in two steps: first, the radar data are corrected for attenuation and in a second step the microwave link derived rainfall is used together with information obtained from distrometer data to calculate the rainfall from the corrected radar reflectivities. A network of twelve rain gauges located in the vicinity of the link path provide a measure of the ‘ground truth’ rainfall. It is shown that the microwave link gives valuable information to improve the radar rainfall estimates of the X-band radar.

Krämer, S.; Verworn, H.-R.; Redder, A.

2005-09-01

431

Incoherent scatter radar contributions  

NASA Astrophysics Data System (ADS)

The contributions of the incoherent scatter radar technique to knowledge of the neutral upper atmosphere of the earth in general and the development of the CIRA 1986 model in particular are discussed. Incoherent radar scattering involves the transmission of a radio wave into the atmosphere and the reception of the energy scattered by the free electrons illuminated by the wave. Attention is given to the chronology of radar contributions to the development of upper atmosphere models, the ion energy balance and continuity equations, exospheric temperatures, and studies of the lower thermosphere.

Oliver, W. L.; Alcayde, D.; Bauer, P.

432

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

433

Observations of meteors using over-the-horizon radar  

NASA Astrophysics Data System (ADS)

Over-the-horizon skywave radars operating in the HF band utilize digital techniques for both radar control and signal processing. These radars are also equipped with frequency management subsystems for the selection of appropriate frequencies for meteor detection based on real-time monitoring of the HF signal environment. Results of meteor observations using such a radar are discussed, including the detection of the Eta Aquarid meteor. A large increase in the echo rate caused by sporadic meteors is obtained as frequencies are reduced below 15 MHz and the underdense echo ceiling rises in altitude. Preliminary observations of highly Doppler shifted echoes traveling at meteoric velocities and identified as meteor head echoes, are presented.

Thomas, R. M.; Netherway, D. J.

434

Multipath track fusion for over-the-horizon radar  

NASA Astrophysics Data System (ADS)

Over-the-horizon skywave radar exploits ionospheric propagation of HF signals to detect targets beyond the line-of-sight horizon. Multiple propagation paths between the radar sites and the target are often encountered, giving multiple resolved detections for a single target. An algorithm for the fusion of multipath tracks is outlined here which accounts for uncertainty in the coordinate registration transformation to ground coordinates. A multihypothesis track association procedure is described which may be appended to existing radar coordinate tracking filters. The probability for each feasible track association hypothesis is computed, and fused estimates for target states in ground coordinates are evaluated for each hypothesis.

Percival, Douglas J.; White, Kruger A.

1997-10-01

435

Generalized Radar Output Simulation.  

National Technical Information Service (NTIS)

Using the outputs from the simulation of overall body motion related to observations at a complex of earth stations, this report develops a model for generating the scattering matrix and radar output voltages. The general multistatic case is treated using...

J. F. A. Ormsby S. H. Bickel

1969-01-01

436

Multimode Radar Altimeter (MRA).  

National Technical Information Service (NTIS)

Multimode radar altimeter functions in the Comet Nucleus Sample Return mission are described. Range measurement gives distance information for navigation; angle tracking can be performed by optical systems. Velocity (three axes) can be obtained by Doppler...

G. Picardi C. Dai R. Seu A. Coradini

1988-01-01

437

Incoherent radar spectra  

Microsoft Academic Search

General expressions for the incoherent scatter spectra are presented. These are relevant for the UHF radar in the monostatic backscatter case (thus excluding only the effect of the magnetic field), based on the Nyquist approach.

Matti K. Vallinkoski

1987-01-01

438

Ultra-wideband radar  

Microsoft Academic Search

Here, we present a description of a block scheme, characteristics, specific features of design and results of testing for a prototype of the ultrawideband (UWB) radar, which has been developed by Russian UWB group researchers at Moscow Aviation Institute at \\

I. Immoreev; E. Ziganshin

2004-01-01

439

Radar investigation of asteroids  

NASA Astrophysics Data System (ADS)

For 80 Sappho, 356 Liguria, 694 Ekard, and 2340 Hathor, data were taken simultaneously in the same sense of circular polarization as transmitted (SC) as well as in the opposite (OC) sense. Graphs show the average OC and SC radar echo power spectra soothed to a resolution of EFB Hz and plotted against Doppler frequency. Radar observations of the peculiar object 2201 Oljato reveal an unusual set of echo power spectra. The albedo and polarization ratio remain fairly constant but the bandwidths range from approximately 0.8 Hz to 1.4 Hz and the spectral shapes vary dramatically. Echo characteristics within any one date's approximately 2.5-hr observation period do not fluctuate very much. Laboratory measurements of the radar frequency electrical properties of particulate metal-plus-silicate mixtures can be combined with radar albedo estimates to constrain the bulk density and metal weight, fraction in a hypothetical asteroid regolith having the same particle size distribution as lab samples.

Ostro, S. J.

440

Digital controller for the Wave Propagation Laboratory's VHF and UHF wind-profiling radars  

NASA Astrophysics Data System (ADS)

Principles are described for operation of a digital system that is used to control the operations of a multiple beam stratospheric-tropospheric (ST) radar system. The digital system, referred to as the radar controller, contains the digital logic for generating the necessary pulse sequences for modulation of the radar transmitter, gating the radar's receiver channels, and sequencing the antenna beams. The radar controller also performs digital-to-analog conversion and coherent averaging of the receiver necessary for signal detection in ST radars. The radar controller is controlled internally by a Z80 microprocessor, and the entire system functions as a peripheral device to a host minicomputer. Block diagrams and detailed circuit schematics for all the custom designed electronics are included.

Moran, K.

1984-09-01

441

The Decrease of the Radar Cross Section of Hypersonic Model  

Microsoft Academic Search

To research the effect of plasma, the radar cross section (RCS) of a hypersonic model is measured in our light gas gun. The spectrum of the received signal and one-dimensional radar image of the model are given. According to this experiment, three-dimensional (3-D) finite-difference time-domain (FDTD) simulations are performed for calculating microwave scattering from a plasma-cloaked conducting model.

Yu Zhefeng; Bu Shaoqing; Liu Sen; Zeng Xuejun; Ma Ping; Shi Anhua

2007-01-01

442

Acoustic micro-Doppler radar for human gait imaging.  

PubMed

A portable acoustic micro-Doppler radar system for the acquisition of human gait signatures in indoor and outdoor environments is reported. Signals from an accelerometer attached to the leg support the identification of the components in the measured micro-Doppler signature. The acoustic micro-Doppler system described in this paper is simpler and offers advantages over the widely used electromagnetic wave micro-Doppler radars. PMID:17407918

Zhang, Zhaonian; Pouliquen, Philippe O; Waxman, Allen; Andreou, Andreas G

2007-03-01

443

Human detection and tracking via Ultra-Wideband (UWB) radar  

Microsoft Academic Search

This paper presents an algorithm for human presence detection and tracking using an Ultra-Wideband (UWB) impulse-based mono-static radar. UWB radar can complement other human tracking technologies, as it works well in poor visibility conditions. UWB electromagnetic wave scattering from moving humans forms a complex returned signal structure which can be approximated to a specular multi-path scattering model (SMPM). The key

SangHyun Chang; Michael T. Wolf; Joel W. Burdick

2010-01-01

444

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

445

Reconfigurable data acquisition system for weather radar applications  

Microsoft Academic Search

Tornado, hazardous weather and flood detection radars demand high-throughput, high-speed data acquisition and processing. Weather-processing systems need to be capable of implementing powerful signal processing algorithms on the raw data collected by the radars. Following processing, data is distributed to the end-user in real-time for timely and accurate detection of imminent weather disasters. Since physical accessibility to such systems is

Rishi Khasgiwale; Luko Krnan; Atchuthan Perinkulam; Russell Tessier

2005-01-01

446

Radar in transition  

Microsoft Academic Search

It is pointed out that radar engineers, at the end of 1984, find their field in transition between the conventional designs of the post War II era and the digitally controlled, solid-state systems which will be in place for the year 2000. The U.S. Navy has two major phased array radar systems in operation, including the rotating three-dimensional (3D) AN\\/SPS-48,

D. K. Barton

1984-01-01

447

Emittance growth due to decoherence and wakefields.  

National Technical Information Service (NTIS)

Suddenly induced coherent centroid oscillations about the closed orbit will decohere due to nonlinearities in the magnetic optics - at the expense of a stored beam's emittance. Collective effects mediated by the vacuum chamber wakefield and dependent on t...

M. G. Minty A. W. Chao W. L. Spence

1995-01-01

448

Current Injection Pumping of Organic Light Emitters.  

National Technical Information Service (NTIS)

The use of thin films of phthalocyanines as current pumped light emitters was investigated. The growth of phthalocyanine films in a stacked ring crystal structure offers the potential for introduction of electronic structure modulation in the film which c...

J. C. Buchholz J. P. Stec M. C. Schutte

1989-01-01

449

Beam emittance measurements on multicusp ion sources  

SciTech Connect

Multicusp ion sources are used for various applications. Presently, the implementation of this type of ion source is planned for the development of an ion beam lithography machine, which will be used for the projection of sub-0.2 {mu}m patterns onto a wafer substrate. Since, for this application, a very good beam quality and a small ion energy spread are required, emittance measurements have been performed on a multicusp ion source for various source conditions. It is shown that the installation of proper capacitors between the extraction electrodes is necessary to avoid rf pickup, which otherwise leads to a distortion of the beam emittance. The influence of the magnetic filter field on the beam emittance has been investigated, and the beam emittance of a dc filament-discharge plasma has also been compared to that of a rf-generated plasma. {copyright} {ital 1996 American Institute of Physics.}

Sarstedt, M.; Lee, Y.; Leung, K.N.; Perkins, L.T.; Pickard, D.S.; Weber, M.; Williams, M.D. [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)

1996-03-01

450

Beam emittance measurements on multicusp ion sources  

SciTech Connect

Multicusp ion sources are used for various applications. Presently, the implementation of this type of ion source planned for the development of an ion beam lithography machine, which will be used for the projection of sub-0.2 {mu}m patterns onto a wafer substrate. Since, for this application, a very good beam quality and a small ion energy spread are required, emittance measurements have been performed on a multicusp ion source for various source conditions. It is shown that the installation of proper capacitors between the extraction electrodes is necessary to avoid rf-pickup, which otherwise leads to a distortion of the beam emittance. The influence of the magnetic filter field on the beam emittance has been investigated, and the beam emittance of a dc filament-discharge plasma has also been compared to that of an rf-generated plasma.

Sarstedt, M.; Lee, Y.; Leung, K.N. [and others

1995-08-01

451

Beam emittance measurements on multicusp ion sources  

SciTech Connect

Multicusp ion sources are used for various applications. Presently, the implementation of this type of ion source is planned for the development of an ion beam lithography machine, which will be used for the projection of sub-0.2 micron patterns onto a wafer substrate. Since, for this application, a very good beam quality and a small ion energy spread are required, emittance measurements have been performed on a multicusp ion source for various source conditions. It is shown that the installation of proper capacitors between the extraction electrodes is necessary to avoid rf-pickup, which otherwise leads to a distortion of the beam emittance. The influence of the magnetic filter field on the beam emittance has been investigated, and the beam emittance of a dc filament-discharge plasma has also been compared to that of an rf-generated plasma.

Sarstedt, M.; Lee, Y.; Leung, K.N.; Perkins, L.T.; Pickard, D.S.; Weber, M.; Williams, M.D.

1995-08-01

452

Tin Oxide Room Temperature Emitter Study.  

National Technical Information Service (NTIS)

The mechanisms of activation and electron emission of tin dioxide film room temperature emitters for cold-cathode application have been investigated. The structure, composition and electrical resistivity of vapor deposited films of various thicknesses and...

H. H. Kedesdy R. Sartore

1978-01-01

453

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

454

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

455

Emission current formation in plasma electron emitters  

SciTech Connect

A model of the plasma electron emitter is considered, in which the current redistribution over electrodes of the emitter gas-discharge structure and weak electric field formation in plasma are taken into account as functions of the emission current. The calculated and experimental dependences of the switching parameters, extraction efficiency, and strength of the electric field in plasma on the accelerating voltage and geometrical sizes of the emission channel are presented.

Gruzdev, V. A.; Zalesski, V. G. [Polotsk State University (Belarus)

2010-12-15

456

Emittance measurement in a magnetic field  

SciTech Connect

Emittance can be measured by intercepting an electron beam on a range thick plate and then observing the expansion of beamlets transmitted through small holes. The hole size is selected to minimize space charge effects. In the presence of a magnetic field the beamlets have a spiral trajectory and the usual field free formulation must be modified. To interpret emittance in the presence of a magnetic field an envelope equation is derived in the appropriate rotating frame. 1 ref.

Boyd, J.K.

1991-04-15

457

Normalized emittance of SITEX negative ion source  

SciTech Connect

An emittance measurement employing two techniques are being made on SITEX. To this end, a 2-D calculation was performed to design the accelerator in order to reduce electric field abberations. The calculated normalized emittance is 6 x 10/sup -4/ IIcm mrad for an angular divergence theta/sub RMS/ approx. = 0.28/sup 0/. Status of the experimental findings are presented and a comparison made to the calculated value which will yield the ion sputter energy.

Stirling, W.L.; Dagenhart, W.K.; Whealton, J.H.; Donaghy, J.J.

1983-01-01

458

Emittance growth due to beam motion  

SciTech Connect

When a beam undergoes a collective oscillation, its emittance tends to grow because of variations in betatron tune which are due to energy spread and chromaticity and to non-linear lattice characteristics. In this paper we estimate the emittance growth in the SSC caused by the measured ground motions at the SSC site and by beam-beam effects in the Jostlein beam-centering scheme. 7 refs.

Ng, King-Yuen (Fermi National Accelerator Lab., Batavia, IL (USA)); Peterson, J.M. (Superconducting Super Collider Lab., Dallas, TX (USA))

1991-05-01

459

Examples of Modifications to Field Emitter Arrays  

NASA Astrophysics Data System (ADS)

A discussion is presented of some of the work reported during the early 21st century describing modifications to field emitter arrays (FEAs). Discussion is focused on FEAs of metals (Mo and Si), of ZnO, and of carbon nanotubes (CNTs). Particular attention is given to modifications that lower the FEA turn-on field, and to the "screening effect" of closely packed emitters in an FEA. Hydrothermal synthesis briefly is described as a preparation technique.

Draeger, Norman A.

2013-06-01

460

Data acquisition system for Doppler radar vital-sign monitor.  

PubMed

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 reflecting off a human subject, a two-channel quadrature receiver can detect periodic movement resulting from cardio-pulmonary activity. The quadrature signal is analyzed using an arctangent demodulation that extracts vital phase information. A data acquisition (DAQ) system is proposed to deal with issues inherent in arctangent demodulation of a quadrature radar signal. PMID:18002443

Vergara, Alexander M; Lubecke, Victor M

2007-01-01

461

11.3: Emittance, space charge, and sharp electron sources  

Microsoft Academic Search

An analytical formula of the emittance of and space charge effects on a sharply curved emitter surface is given. The 3D formulation makes use of the Point Charge Model (PCM) of a unit cell emitter coupled with a trajectory analysis to follow electrons to an evaluation plane where emittance is determined. The single tip theory extended to an array predicts

Kevin L. Jensen; P. G. O'Shea; D. W. Feldman

2010-01-01

462

Experimental investigation of impulse radar for mitigation of effects of radar absorbing materials  

Microsoft Academic Search

This article uses experimental methods from the two areas of frequency-domain and time-domain to investigate electromagnetic scattering associated with targets coated with wave absorbent materials. Results clearly show that UWB signals have a 10-12dB advantage coping with targets coated with wave absorbent materials as compared to the narrow band signals of conventional radar. The explanation is that ultra wide waveband

He Jianguo; Lu Zhongliang; Su Yi

1995-01-01

463

Ultrawideband imaging radar based on OFDM: system simulation analysis  

NASA Astrophysics Data System (ADS)

Orthogonal frequency division-multiplexing (OFDM) is rapidly emerging as a preferred method of UWB signaling in commercial applications aimed mainly at low-power, high data-rate communications. This paper explores the possibility of applying OFDM to use in imaging radar technology. Ultra-wideband nature of the signal provides for high resolution of the radar, whereas usage of multi-sub-carrier method of modulation allows for dynamic spectrum allocation. Robust multi-path performance of OFDM signals and heavy reliance of transceiver design on digital processors easily implemented in modern VLSI technology make a number of possible applications viable, e.g.: portable high-resolution indoor radar/movement monitoring system; through-the-wall/foliage synthetic aperture imaging radar with a capability of image transmission/broadcasting, etc. Our work is aimed to provide a proof-of-concept simulation scenario to explore numerous aspects of UWB-OFDM radar imaging through evaluating range and cross-range imaging performance of such a system with an eventual goal of software-defined radio (SDR) implementation. Stripmap SAR topology was chosen for modeling purposes. Range/cross-range profiles were obtained along with full 2-D images for multi-target in noise scenarios. Model set-up and results of UWB-OFDM radar imaging simulation study using Matlab/Simulink modeling are presented and discussed in this paper.

Garmatyuk, Dmitriy

2006-06-01

464

Monitoring internal organ motion with continuous wave radar in CT.  

PubMed

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. PMID:24007166

Pfanner, Florian; Maier, Joscha; Allmendinger, Thomas; Flohr, Thomas; Kachelrieß, Marc

2013-09-01

465

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

466

Multi-static synthetic aperture radar image formation  

Microsoft Academic Search

In this paper, we consider a multi-static synthetic aperture radar (SAR) imaging scenario where a swarm of airborne antennas, some of which are transmitting, receiving or both, are traversing arbitrary flight trajectories and transmitting arbitrary waveforms without any form of multiplexing. The received signal at each receiving antenna may be interfered by the scattered signals from multiple transmitters and the

V. P. Krishnan; J. Swoboda; C. E. Yarman; B. Yazici

2009-01-01

467

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

468

Tracking multiple manoeuvering targets in a network of passive radars  

Microsoft Academic Search

This paper addresses the problem of tracking multiple targets in a net of passive (angle only) 2D- of 3D-radar (azimuth or azimuth and elevation). No decentralised local bearing tracks are built, but measurements are fused on a central level. No signal or signal following information is used. We assume multiple coverage, high probability of detection and consider resolution conflicts of

R. Baltes; G. van Keuk

1995-01-01

469

Ambiguity Function Analysis of Wireless LAN Transmissions for Passive Radar  

Microsoft Academic Search

Wireless transmission is becoming an increasingly widely available source of transmissions for passive radar detection. In this paper, we present a detailed analysis of the ambiguity function (AF) of a range of typical IEEE 802.11 signals obtained during a series of experimental trials. Theoretical analysis has been used to identify the average properties of basic signal types in terms of

Fabiola Colone; Karl Woodbridge; Hui Guo; David Mason; Chris J. Baker

2011-01-01

470

Random Body Movement Cancellation in Doppler Radar Vital Sign Detection  

Microsoft Academic Search

The complex signal demodulation and the arctangent demodulation are studied for random body movement cancellation in quadrature Doppler radar noncontact vital sign detection. This technique can be used in sleep apnea monitor, lie detector, and baby monitor to eliminate the false alarm caused by random body movement. It is shown that if the dc offset of the baseband signal is

Changzhi Li; Jenshan Lin

2008-01-01

471

Can the radar penetrate Martian polar deposits ?  

NASA Astrophysics Data System (ADS)

Layered stratigraphy of Martian polar deposits is believed %thought to contain a record of climatic history of Mars. Investigation %Exploration of stratigraphy of Martian polar sheets %by means of ground-penetrating radar would provide valuable information about the history and evolution of the planet and its water balance. An appropiate instrument for deep investigation of polar deposits is a ground-penetrating radar (GPR). Propagation of electromagnetic waves through such a complicated medium like Martian polar layered deposits are governed by two kinds of factors. Physical and chemical composition of the polar sheets determines its electrical properties, i.e. wave velocity and attenuation. On the other hand, layered structure of polar sheets and its geometrical parameters regulate dispersive properties of such medium. We simulated radio wave propagation in polar sheets under various assumptions about both these groups of parameters, both analytically and numerically. Basic dispersive properties of studied inhomogeneous medium were inferred from the solution of dispersion equation for regularly periodical medium (the Kronig-Penney problem). The geometrical parameters of the structure were chosen equal to characteristic parameters of real polar layered deposits, inferred from published observational data. Also immediate numerical simulations of ultra wide band (UWB) radar signals, propagated through polar sheets, were performed. Electrical properties of material of polar sheets varied in wide range of values, according to published results on physical and chemical composition of polar sheets. We found that, under most commonly made assumptions on chemical composition, the characteristic geometrical parameters of layered structure imply significant disptortion of radar signals at frequencies higher than 1 MHz. For this reason, a low frequency ( below 1 MHz ) radar appears to be better choise for investigation of Martian polar sheets.

Ilyushin, Ya. A.

472

Initial results of land-reflected GPS bistatic radar measurements in SMEX02  

Microsoft Academic Search

To investigate scattering of Global Positioning System (GPS) signals from terrain and the potential for remotely sensing soil moisture with the L-band GPS bistatic radar concept, a prototype GPS bistatic radar participated in airborne measurements during the Soil Moisture Experiment 2002 (SMEX02). A 12-channel GPS navigation receiver, modified to perform bistatic radar measurements, was mounted on the NCAR C-130 aircraft

Dallas Masters; Penina Axelrad; Stephen Katzberg

2004-01-01

473

Classification of Ground Clutter and Anomalous Propagation Using Dual-Polarization Weather Radar  

Microsoft Academic Search

This paper presents the results of a study designed to classify weather radar clutter echoes obtained from ground-based dual-polarization weather radar systems. The clutter signals are due to ground clutter, sea clutter, and anomalous propagation echoes, which represent sources of error in quantitative radar rainfall estimation. Fuzzy and Bayes classifiers are evaluated as an alternative approach to traditional polarimetric-based methods.

Miguel Angel Rico-Ramirez; Ian David Cluckie

2008-01-01

474

The Advanced Simulation System for MMW Imaging Radar Seeker onboard Air-to-air Missile  

Microsoft Academic Search

Millimeter wave (MMW) radar is booming in application to target seeker onboard the air-to-air missile (AAM), which has the capability to obtain all-weather radar images for auto target recognition (ATR) and intelligent active homing guidance. An advanced simulation system for MMW imaging radar seekers of AAM was introduced in this paper. The system is composed of parameter initialization module, signal

Sun Yumeng; C. Jie; G. Caihong; S. Bing; Z. Yinqing

2006-01-01

475

Numerical simulations of radar surface air pressure measurements at O2 bands  

Microsoft Academic Search

An active microwave method is investigated for measuring surface air pressure by using radar reflections at frequencies around 53-55 GHz O2 bands. The numerical simulation results for homogeneous backgrounds show that with an airborne radar working at these O2 absorption bands, the rms errors of the radar surface pressure estimations with 15-dB signal-to-noise ratio can be as low as 4-7

Bing Lin; Yongxiang Hu

2005-01-01

476

Tactical and atmospheric coherent laser radar technology  

Microsoft Academic Search

CO2 laser radar systems operating in the infrared region are discussed as regards their tactical and remote sensing applications. Coherent and incoherent detection methods for lidar echoes are compared, and the increased sensitivity offered by heterodyne (coherent) detection is demonstrated through an analysis of signal-to-noise ratios. A CO2 TEA laser rangefinder and a small, tripod-mounted CO2 imaging lidar are then

A. V. Jelalian; W. H. Keene; E. F. Pearson

1983-01-01

477

Bistatic Radar In Space A New Dimension In Imaging Radar  

Microsoft Academic Search

Based on a set of examples, this paper shows that bistatic space radar systems can have important capabilities for special imaging radar applications. It explains' the different categories of bistatic space radars as there are single orbit systems, crossing orbit systems, tethered systems and systems with geostationary\\/ge osynchronous transmitters (GEO-BISAR). It discusses the ideas of mixed systems, where aircrafts are

Hans Martin Braun; Philipp Hartl

1989-01-01

478

Studies on Radar and Non-radar Sensor Networks.  

National Technical Information Service (NTIS)

During the period of 12/1/2005--5/30/2006, we expanded our research from generic wireless sensor networks to radar sensor networks. For radar sensor networks, we performed the following preliminary studies: (1) Waveform design and diversity in radar senso...

Q. Liang

2006-01-01

479

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

480

Terahertz radar cross section measurements  

Microsoft Academic Search

We present the result of terahertz radar cross section measurements on various objects including models of aircraft fighters. Application of a time domain system provides both values of radar cross section and ranging information.

Krzysztof Iwaszczuk; Henning Heiselberg; Peter Uhd Jepsen

2010-01-01

481

CFAR detection for multistatic radar  

Microsoft Academic Search

A multistatic radar system with n transmitters and one receiver is modelled. Several CFAR algorithms for detection are introduced. The proposed CFAR detectors are simulated and the performances are compared with the performance of a monostatic radar of higher power.

Vahideh Amanipour; Ali Olfat

2008-01-01

482

Delay Modeling of Bipolar ECL/EFL (Emitter-Coupled Logic/Emitter-Follower-Logic) Circuits.  

National Technical Information Service (NTIS)

This report deals with the development of a delay-time model for timing simulation of large circuits consisting of Bipolar ECL(Emitter-Coupled Logic) and EFL (Emitter-Follower-Logic) networks. This model can provide adequate information on the performance...

A. T. Yang

1986-01-01

483

Application of Near-Space Passive Radar for Homeland Security  

NASA Astrophysics Data System (ADS)

To protect the homeland from terrorist attacks employing explosive devices, revolutionary advances across a wide range of technologies are required. Inspired by recent advances in near-space (defined as the region between 20 km and 100 km), this paper proposes a new passive radar system using opportunistic transmitter as an illuminator and near-space platform as a receiver. This concept differs substantially from current radars. This system can be operated as a passive bistatic or multistatic radar and hence largely immune to jamming. By placing the receiver in near-space platforms, many functions that are currently performed with satellites or airplanes could be performed much more cheaply and with much greater operational utility. These advantages make near-space passive attractive for a variety of applications, many of which fit well with the needs of homeland security. This paper details the role of near-space passive radar as sensor system that can support homeland security applications. The strengths and weakness of near-space passive radar, compared to current spaceborne and airborne radars, are detailed. The signal models and processing algorithms for near-space passive radar are provided. It is shown that the use of cost effective near-space platforms can provide the solutions that were previously thought to be out of reach to remote sensing and government customers.

Wang, Wenqin

2007-03-01

484

Support Vector Clustering and Type-Entropy Based Joint De-interleaving\\/recognition System of Radar Pulse Sequence  

Microsoft Academic Search

Modern electronic warfare faces complex and dense pulses environments, which brings a severe challenge to radar signal sorting.\\u000a Support Vector Clustering (SVC) is used into the radar signal sorting and the notion of type-entropy is presented in this\\u000a paper. And combine the recognition technology based on type-entropy with the sorting technology based on SVC to constitute\\u000a a novel radar sequence

Qiang Guo; Zheng Li; Xingzhou Zhang

485

SIR-B (Shuttle Imaging Radar) images  

NASA Astrophysics Data System (ADS)

Space Shuttle Mission 41G was launched from Kennedy Space Center on 5 October 1984. Aboard the instrument pallet was the 1.28 GHz (L-band) Shuttle Imaging Radar (SIR-B) intended to obtain SAR images for geology, agriculture, forestry, hydrology, and ocean sciences. Data were intended to be transmitted to earth via a Ku band communication link with the Tracking and Data Relay Satellite (TDRS). Unfortunately, the shuttle's trainable Ku communication antenna failed to lock onto the TDRS, making high rate data transmission impossible. A real-time-revised observation program, of much smaller scale than the original plan, was substituted making use of an onboard tape recorder. The flight crew recorded radar data on the recorder and then reoriented the shuttle itself, with the Ku antenna fixed, to point to TDRS and transmit the data. The revised plan eliminated about 80 percent of the planned data swaths and shortened the remainder. A number of errors crept into the SIR-B experiments as a result of the sudden and complete reprogramming as well as a problem in latching the radar antenna. Finally, an electrical problem in the radar caused an 8-10 dB reduction in signal-to-noise ratio.

1985-05-01

486

A 30 GHz Variable Gain Amplifier With High Output Voltage Swing for Ultra-Wideband Radar  

Microsoft Academic Search

This paper reports on the analysis, design and characterization of a 30 GHz fully differential variable gain amplifier for ultra-wideband radar systems. The circuit consists of a variable gain differential stage, which is fed by two cascaded emitter followers. Capacitive degeneration and inductive peaking are used to enhance bandwidth. The maximum differential gain is 11.5 dB with plusmn1.5 dB gain

Benjamin Sewiolo; Georg Fischer; Robert Weigel

2009-01-01

487

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

488

The Clementine Bistatic Radar Experiment  

Microsoft Academic Search

During the Clementine 1 mission, a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle, beta, for selected lunar areas. Observations of the lunar south pole yield a same-sense polarization enhancement around beta = 0. Analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole. Radar

S. Nozette; C. L. Lichtenberg; P. Spudis; R. Bonner; W. Ort; E. Malaret; M. Robinson; E. M. Shoemaker

1996-01-01

489

Scanning ARM Cloud Radar Handbook.  

National Technical Information Service (NTIS)

The scanning ARM cloud radar (SACR) is a polarimetric Doppler radar consisting of three different radar designs based on operating frequency. These are designated as follows: (1) X-band SACR (X-SACR); (2) Ka-band SACR (Ka-SACR); and (3) W-band SACR (W-SAC...

K. Johnson K. Widener N. Bharadwaj

2012-01-01

490

The Venus Radar Mapper mission  

Microsoft Academic Search

The Venus Radar Mapper (VRM) mission is sponsored by NASA to put a single spacecraft in orbit around Venus to map the surface using a synthetic aperture mapping radar. This paper describes the VRM mission at its present state of design. The science objectives and project constraints are described. Key features of the spacecraft system and radar system are discussed.

E. Cutting; J. H. Kwok; S. N. Mohan

1984-01-01

491

A radar tour of Venus  

Microsoft Academic Search

The surface of Venus is briefly characterized in a summary of results obtained by the Soviet Venera 15 and 16 8-cm synthetic-aperture radars, IR radiometers, and radar altimeters. A series of radar images, mainly from Kotelnikov et al. (1984), are presented and discussed, and the descent vehicles to be released by the two Vega spacecraft as they pass Venus in

J. K. Beatty

1985-01-01

492

Radar model with terrain effects  

NASA Astrophysics Data System (ADS)

This thesis presents a novel naval radar model which computes radar detection in the presence of land masses. The model is an interactive computer program which accepts scenarios and radar parameters from the user and displays a map of the area indicating where targets can and cannot be detected. The resulting map can be displayed at the user's computer terminal or printed offline.

Meritt, J. W.

1982-03-01

493

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

494

Studies on Radar Sensor Networks.  

National Technical Information Service (NTIS)

During the period of 12/8/2006-6/30/2007, we performed the following studies in radar sensor network: (1) Sense-through-foliage target detection using UWB radar sensor network based on real-world data; (2) Foliage clutter modeling using UWB radars; (3) Ou...

Q. Liang

2007-01-01

495

Millimeter Radar Sea Return Study.  

National Technical Information Service (NTIS)

A site selection process was performed for a planned field exercise to measure radar sea clutter reflectivity at low grazing angles using several radar frequencies between 9.5 and 95 GHz. A detailed test plan was developed to collect calibrated radar cros...

R. N. Trebits

1979-01-01

496

Polarimetric Monopulse Radar Intelligent Emulator  

Microsoft Academic Search

For debugging polarimetric monopulse radar and testing polarization algorithms, a new polarimetric monopulse radar intelligent emulator is proposed and designed in this paper. The polarization information, as a basic character of the target echo, plays an important role in modern radar detection nowadays. The polarization algorithms are developed with rapid speed. It is not realistic to test all algorithms on

Jin Tao; Qi Xiaohui; Yuan Shuqing; Qiao Xiaolin; Zhang Min; Zhang Qunxing

2007-01-01

497

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