Note: This page contains sample records for the topic radar emitter signals from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

Cumulants-based Radar Specific Emitter Identification  

Microsoft Academic Search

In this paper we consider the problem of Radar Specific Emitter Identification (SEI) with the aim of distinguishing among several transmitting sources of the same kind which is a very hot topic in the device forensic field. At the design stage, we introduce a classification technique based on some suitable features evaluated from the cumulants of the signal emitted by

A. Aubry; A. Bazzoni; V. Carotenuto; A. De Maio; P. Failla

2011-01-01

2

Feature Extraction of Radar Emitter Harmonic Power Constraint Based on Nonlinear Characters of the Amplifier  

Microsoft Academic Search

In radar countermeasures systems, because each emitter has its own electromagnetic properties inside its transmitted signal, the specific emitter can be identified using received radar signals. Traditionally, the specific emitter identification (SEI) depends on analyzing the time-frequency structure within the usage band. In this paper, a new SEI feature extraction approach based on autocorrelation analysis is proposed. To characterize the

Zhibin Yu; Chunxia Chen; Weidong Jin; Gexiang Zhang

2009-01-01

3

The method for radar signal recognition  

NASA Astrophysics Data System (ADS)

One of the principal functions of the ESM/ELINT system is gathering basic information from entire electromagnetic spectrum and its analysis. In most cases, based only on primary features of incoming radar signals, the modern electronic intelligence system cannot recognize the different devices of the same type or class. The radar signal is the source of information about recognized object, which is propagated into surrounding environment. Radar emitter identification based on a collection of received radar signals is a subject of wide interest in both civil and military applications. To classify radar emitters in the surrounding environment we need to explore the detailed structure inside each pulse. An emitter has its own electrical signal structure inside each of its transmitted pulses due to both intentional and unintentional modulations. It is very difficult work to perfectly employ a microwave sensors in the combat identification, because it is a composite task that involves pulse measurements, features extraction, normalization, selection, classification (recognition) and verification.

Kawalec, A.; Owczarek, R.

2006-11-01

4

Combining Multiple SVM Classifiers for Radar Emitter Recognition  

Microsoft Academic Search

Radar emitter recognition is of great importance in modern ELINT and ESM systems. The conventional methods for emitter recognition usually use one classifier. For specific emitter recognition, there are slight differences between the feature vectors from radars with the same type. So the recognition result of single classifier is unreliable and instable. In this paper we propose a new combining

Lin Li; Hongbing Ji

2009-01-01

5

Metrics for Emitter Selection for Multistatic Synthetic Aperture Radar.  

National Technical Information Service (NTIS)

A bistatic implementation of synthetic aperture radar (SAR) to form images of the ground from an aircraft makes use of separate emitters and receivers. When not using cooperative emitters, ground based communications systems can provide illumination. One ...

S. R. Stevens

2013-01-01

6

Chaotic signals in radar?  

Microsoft Academic Search

Chaotic signals add to the design repertoire for radar. This paper discusses the properties of chaotic signals, their generation and use, including transmitter hardware and efficiency, with reference to results in communications research and recent theoretical and practical results in sonar, and development throughout the world for radar. Practical issues arising from the unique properties of chaotic systems are considered.

S. A. Harman; A. J. Fenwick; C. Williams

2006-01-01

7

Radar Background Signal Reduction Study.  

National Technical Information Service (NTIS)

This report summarizes a study whose objective was to identify materials and/or techniques to reduce radar background signals for ground plane radar cross section (RCS) ranges. Background signal reduction is essential for improving the accuracy of RCS mea...

E. F. Knott C. J. Ray M. S. West R. J. Wohlers

1980-01-01

8

Ghost Signals In Allison Emittance Scanners  

NASA Astrophysics Data System (ADS)

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.; Leitner, M.; Moehs, D. P.; Keller, R.; Welton, R. F.

2005-03-01

9

Signals and processing for random signal radars  

Microsoft Academic Search

Signals and associated processing techniques are developed which improve the performance, simplify the implementation, and are more amenable to adaptive operation for radars using the random signal concept. These goals are accomplished through the use of a signal set that is composed of a deterministic spreading function, a binary random or pseudo-random noise source, and a possibly random or pseudo-random

G. S. Moore

1980-01-01

10

Radar signal design using chaotic signals  

Microsoft Academic Search

The use of chaotic signals in radar imaging applications present particular advantages as they behave like pseudo noise, have a wide band, and are easy to generate. A chaotic frequency modulated (FM) sine wave is an example of a chaotic signal that can yield higher transmitted mean power when peak-power limited transmitters are used. Unlike the random FM signal, the

Ali Ashtari; Gabriel Thomas; Hector Garcés; Benjamin C. Flores

2007-01-01

11

Radar signal categorization using a neural network  

NASA Technical Reports Server (NTRS)

Neural networks were used to analyze a complex simulated radar environment which contains noisy radar pulses generated by many different emitters. The neural network used is an energy minimizing network (the BSB model) which forms energy minima - attractors in the network dynamical system - based on learned input data. The system first determines how many emitters are present (the deinterleaving problem). Pulses from individual simulated emitters give rise to separate stable attractors in the network. Once individual emitters are characterized, it is possible to make tentative identifications of them based on their observed parameters. As a test of this idea, a neural network was used to form a small data base that potentially could make emitter identifications.

Anderson, James A.; Gately, Michael T.; Penz, P. Andrew; Collins, Dean R.

1991-01-01

12

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

13

Radar Ambiguity Function for Random Intrapulse-Modulated Radar Signals.  

National Technical Information Service (NTIS)

The radar ambiguity function for random intrapulse-modulated signals with constant frequency and amplitude for each sub-pulse was considered. The amplitude and frequency of each sub-pulse were random variables. The amplitude modulation (AM) and frequency ...

H. N. Hebert

1974-01-01

14

Wavelet denoising of pulsed laser radar signals  

NASA Astrophysics Data System (ADS)

Signal processing is pivotal to laser radar system. Information like range, target's signature, etc. can be obtained from the processed laser signals. The received laser pulses for pulse laser radar are modeled. A wavelet filter is designed to denoise the contaminated laser signals. For the given laser signals, the filter based on the combination of correlation and thresholding is proposed. The gain of the filter is compared with the traditional thresholding method. It is shown that the combination of the correlation and thresholding denoising method is more effective for the weak laser radar signal processing compared with the traditional thresholding method.

Cai, Xiping; Wang, Lina; Yang, Shuang; Liu, Jianbo

2010-11-01

15

Interception of LPI Radar Signals.  

National Technical Information Service (NTIS)

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, namely search, anti-ship missile (ASM) s...

J. P. Lee

1991-01-01

16

An application of the synthetic emitter-array method to improve GPR signals  

NASA Astrophysics Data System (ADS)

Methods that employ arrays of emitters are potentially useful in improving weak or ambiguous signals in ground penetrating radar (GPR) prospecting. As in the seismic case, the electromagnetic responses from the subsurface can be obtained by employing true composite sources or synthesized from single emitter responses that are acquired with variable offset, both possibilities leading to similar results. In this article, the synthetic emitter-array method is examined as a way of improving GPR signals. Modeling of transmitted wave-fronts is carried out to analyze how the targets can be illuminated so that the reflected signals are effectively reinforced. The method is applied to different targets. A methodology that simultaneously increases the signal to noise ratio and the lateral coherence of the events is examined in order to facilitate the interpretation of the GPR data. Finally, the synthetic emitter-array method is successfully applied in a case study to determine the width and depth of mud walls at the Palo Blanco archaeological site in Argentina.

Cedrina, Lorena; Bonomo, Néstor; Osella, Ana

2010-03-01

17

Noggrannhet Vid Laegesbestaemning Med Hjaelp av Radarsignalspaning (Accuracy in Geolocation of Radar Emitters).  

National Technical Information Service (NTIS)

One of the core competencies at the department of Electronic Warfare Systems lies within the area of geolocation of radar emitters. This research activity has since 2003 been conducted within the research project 'VMSiNBF.' This report describes an approx...

B. Lindgren D. Henriksson M. Wikstroem

2005-01-01

18

A comparison of radar signal classifiers  

Microsoft Academic Search

The performances of two neural network classifiers are compared with those of two conventional information theoretic pattern classifiers for the classification of radar returns. Each of the classifiers is applied to the problem of discriminating between the radar signal returns of five commercial aircraft at various azimuth angles. The neural network classifiers are frequency-sensitive competitive learning (FSCL) and FSCL learning

Stanley C. Ahalt; Tzyy-ping Jung; Ashok K. Krishnamurthy

1990-01-01

19

A comparison of radar signal classifiers  

Microsoft Academic Search

The performances of two neural network classifiers are compared with those of two conventional information theoretic pattern classifiers for the classification of radar returns. Each of the classifiers is applied to the problem of discriminating between the radar signal returns of five commercial aircraft at various azimuth angles. The neural netowrk classifiers studied are frequency-sensitive competitive learning (FSCL) and FSCL

Stanley C. Ahalt; Tzyy-Ping Jung; Ashok K. Krishnamurthy

1990-01-01

20

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

21

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.

22

Signal processing in a high resolution radar  

Microsoft Academic Search

Theory and signal processing of a high resolution radar with a time-bandwidth-product of about 1 million are presented. Limits of range-resolution of two scatterers with unknown distance are described by means of a statistical theory of resolution. The corresponding resolution-filter results in the conventional matched filter for the limiting case of a delta impulse autocorrelation function of the radar signal.

K. Kruecker; D. Perkuhn

1977-01-01

23

Phase unwrapping algorithms test for spacebome IFSAR radar using radar signal simulator  

Microsoft Academic Search

Absnact - To test radar processing signal algorithms we need a raw radar data. One opportunity to obtain them is record raw radar data, the second opportunity is to generate synthetic data. The presented Radar Signal Simulator (RSS) was used for testing different radar processing algorithms, among other things also in IFSAR algorithms. In the paper Goldstein filtration and unwrapping

Artur Gromek; P. Jobkiewicz; K. Kulpa; M. Smolarczyk

2004-01-01

24

Multichannel optical correlator for radar signal processing.  

PubMed

A multichannel coherent optical processor for radar signals is described in which pulse compression is achieved by matched spatial filtering. The optical system can be used for phased array, linear frequency modulated pulse burst, or other radar systems. However, only its application to linear phased array signal processing is discussed in depth. From the output optical pattern, one can obtain data on the target's fine range and azimuth (for a phased array) or fine range and Doppler (for a pulse burst radar) etc. PMID:20203724

Casasent, D; Klimas, E

1978-07-01

25

Radar signal simulator and its usage for interferometric SAR radars phase unwrapping algorithms test  

Microsoft Academic Search

This work presents a radar signal simulator and its usage for interferometric SAR radars phase unwrapping algorithms test. Paper presents selected phase unwrapping algorithms test using examples of phase functions and simulated raw radar data.

Krzysztof Kulpa; Maciej Smolarczyk; G. Tanski; A. Gromek; P. Jobkiewicz

2004-01-01

26

Power Efficient Radar Signal Processor.  

National Technical Information Service (NTIS)

Power efficiency and ease of programming are key issues in the implementation of real-time systems in airborne and space-based applications. This paper describes a radiation tolerant processor designed for space-based Radar applications. The proposed syst...

D. Fitzgerald G. Bright J. Rooks Y. Salama

2005-01-01

27

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

28

Packet radar spectrum recovery for physiological signals.  

PubMed

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

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

2013-01-01

29

Radar transponder apparatus and signal processing technique.  

National Technical Information Service (NTIS)

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 ...

R. M. Axline G. R. Sloan R. E. Spalding

1994-01-01

30

Digital Processing of Meteorological Radar Signals.  

National Technical Information Service (NTIS)

The paper describes a signal processing technique which reduces the variance to an acceptale level for quantitative measurements using the log power output from the radar as the variable. The decrease in variance is a function of the number of samples tak...

D. Sirmans

1972-01-01

31

Quadrature Compressive Sampling for Radar Signals  

NASA Astrophysics Data System (ADS)

Quadrature sampling has been widely applied in coherent radar systems to extract in-phase and quadrature (I and Q) components in the received radar signal. However, the sampling is inefficient because the received signal contains only a small number of significant target signals. This paper incorporates the compressive sampling (CS) theory into the design of the quadrature sampling system, and develops a quadrature compressive sampling (QuadCS) system to acquire the I and Q components with low sampling rate. The QuadCS system first randomly projects the received signal into a compressive bandpass signal and then utilizes the quadrature sampling to output compressive I and Q components. The compressive outputs are used to reconstruct the I and Q components. To understand the system performance, we establish the frequency domain representation of the QuadCS system. With the waveform-matched dictionary, we prove that the QuadCS system satisfies the restricted isometry property with overwhelming probability. For K target signals in the observation interval T, simulations show that the QuadCS requires just O(Klog(BT/K)) samples to stably reconstruct the signal, where B is the signal bandwidth. The reconstructed signal-to-noise ratio decreases by 3dB for every octave increase in the target number K and increases by 3dB for every octave increase in the compressive bandwidth. Theoretical analyses and simulations verify that the proposed QuadCS is a valid system to acquire the I and Q components in the received radar signals.

Xi, Feng; Chen, Shengyao; Liu, Zhong

2014-06-01

32

A signal level simulator for netted radar waveforms evaluation  

Microsoft Academic Search

When evaluating the performances of radar waveforms, it is crucial to understand how the signal is affected by multiple interactions with the environment and the system hardware. Analysis of complex radar systems, such as multistatic and netted designs (see Fig. 1) is often intractable without the application of a dedicated radar simulation system. Recent research into radar simulation has focused

Y. Paichard; M. Brooker; M. Inggs

2009-01-01

33

Signal level Simulator for netted text radar waveforms evaluation  

Microsoft Academic Search

When evaluating the performances of radar waveforms, it is crucial to understand how the signal is affected by multiple interactions with the environment and the system hardware. Analysis of complex radar systems, such as multistatic and netted designs (see Figure 1) is often intractable without the application of a dedicated radar simulation system. Recent research into radar simulation has focused

Yoann Paichard; Marc Brooker; Michael Inggs

2010-01-01

34

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

35

Digital signal processing for target detection in FMCW radar  

NASA Astrophysics Data System (ADS)

The paper describes a method of digital signal processing for extracting and isolating targets in the return signal of an FMCW radar. Digital filtering of the frequency spectrum of the return signal is followed by nonlinear optimization to detect the presence of multiple targets amid clutter. Results using a practical radar show that the method gives enhanced detection of weak return signals.

Carr, A. E.; Cuthbert, L. G.; Olver, A. D.

1981-10-01

36

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

37

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

38

The ambiguity function of the step frequency radar signal processor  

Microsoft Academic Search

In step frequency radar, the frequency of each pulse is increased in steps to achieve large effective bandwidth sequentially instead of instantaneously and thus easing the requirements on the analog to digital converter (ADC) and other hardware. This paper discusses the step frequency radar and its associated signal processing, and it investigates this type of radar with the ambiguity function.

G. S. Gill; Jen-Chih Huang

1996-01-01

39

Optical computing techniques for radar and sonar signal processing  

Microsoft Academic Search

New applications of the use of coherent optical processing techniques, especially matched spatial filtering and input format control, in radar and sonar signal processing are reviewed. Emphasis is given to specific problems such as long coded waveforms of thousands of bits, processing of coded phased array and pulse burst radar waveforms, generation of the ambiguity function for use in radar

D. Casasent

1977-01-01

40

Digital signal processing for target detection in FMCW radar  

Microsoft Academic Search

The paper describes a method of digital signal processing for extracting and isolating targets in the return signal of an FMCW radar. Digital filtering of the frequency spectrum of the return signal is followed by nonlinear optimization to detect the presence of multiple targets amid clutter. Results using a practical radar show that the method gives enhanced detection of weak

A. E. Carr; L. G. Cuthbert; A. D. Olver

1981-01-01

41

Analog radar signal design and digital signal processing a Heisenberg nilpotent Lie group approach  

NASA Astrophysics Data System (ADS)

Introductory discussion of radar principles Analog radar signal design The radar synthesis problem The radar invariant problem The compact Heisenberg nilmanifold A geometric approach to cardinal spline interpolation Finite phase space, and finite Fourier transform The phase discontinuity of Fourier optics Conclusions References

Schempp, Walter

42

Auxiliary signal processing system for a multiparameter radar  

NASA Technical Reports Server (NTRS)

The design of an auxiliary signal processor for a multiparameter radar is described with emphasis on low cost, quick development, and minimum disruption of radar operations. The processor is based around a low-cost digital signal processor card and personal computer controller. With the use of such a concept, an auxiliary processor was implemented for the NCAR CP-2 radar during a 1991 summer field campaign and allowed measurement of additional polarimetric parameters, namely, the differential phase and the copolar cross correlation. Sample data are presented from both the auxiliary and existing radar signal processors.

Chandrasekar, V.; Gray, G. R.; Caylor, I. J.

1993-01-01

43

Applying digital VLSI technology to radar signal processing  

Microsoft Academic Search

In spite of great advances in radar signal processing related to technological progress, the present digital signal processing (DSP) capability, still falls well short of what could be specified by a radar designer. It is, therefore, necessary to pay attention to the special characteristics of VLSI circuits in order to be able to exploit silicon as fully as possible as

J. B. G. Roberts; P. Simpson; B. C. Merrifield

1986-01-01

44

Analysis of Low Probability of Intercept (LPI) Radar Signals Using Cyclostationary Processing  

NASA Astrophysics Data System (ADS)

LPI (Low Probability of Intercept) radar is a class of radar systems that possess certain performance characteristics that make them nearly undetectable by today's digital intercept receivers. This presents a significant tactical problem in the battle space. To detect these types of radar, new digital receivers that use sophisticated signal processing techniques are required This thesis investigates the use of cyclostationary processing to extract the modulation parameters from a variety of continuous-wave (CW) low-probability-of-intercept (LPI) radar waveforms. The cyclostationary detection techniques described exploit the fact that digital signals vary in time with single or multiple periodicities, because they have spectral correlation, namely, non-zero correlation between certain frequency components, at certain frequency shifts. The use of cyclostationary signal processing in a non-cooperative intercept receiver can help identify the particular emitter and can help develop electronic attacks. LPI CW waveforms examined include Frank codes, polyphase codes (Pt through P4), Frequency Modulated CW (FMCW), Costas frequencies as well as several frequency-shift-keying/phase-shift-keying (FSK/PSK) waveforms. It is shown that for signal-to-noise ratios of OdB and -6 dB, the cyclostationary signal processing can extract the modulation parameters necessary in order to distinguish among the various types of LPI modulations.

Lime, Antonio F., Jr.

2002-09-01

45

Synthetic Aperture Radar Using Random Signals. Part I. Discrete Arrays.  

National Technical Information Service (NTIS)

The report introduces a signal processor structure for synthetic array processing in conjunction with a random signal radar. Displayed in its elemental form, the processor configuration consists of a bank of cross-correlators followed by a tapped delay li...

G. R. Cooper K. W. Moran

1973-01-01

46

Goldstone solar system radar signal processing  

NASA Technical Reports Server (NTRS)

A performance analysis of the planetary radar data acquisition system is presented. These results extend previous computer simulation analysis and are facilitated by the development of a simple analytical model that predicts radar system performance over a wide range of operational parameters. The results of this study are useful to both the radar systems designer and the science investigator in establishing operational radar data acquisition parameters which result in the best systems performance for a given set of input conditions.

Jurgens, R. F.; Satorius, E.; Sanchez, O.

1992-01-01

47

Nonsinusoidal radar signal design for stealth targets  

Microsoft Academic Search

The detection of stealth point targets challenges the design of conventional radars using sinusoidal carriers since the objective of stealth technology is to reduce the radar cross section (RCS) of targets to a level where the radar receiver cannot detect the target. While there are a number of techniques employing different technologies to reduce the RCS of targets, shaping and

Nasser J. Mohamed

1995-01-01

48

Application of Signal Corps Radar to Combat Surveillance  

Microsoft Academic Search

The U. S. Army Signal Research and Development Laboratory has developed several types of radar equipment to fulfill the combat requirements of the Field Army. To aid in obtaining an all-weather continuous surveillance capability, the AN\\/PPS-4 and AN\\/TPS-25 ground radar sets were developed. To extend and supplement their coverage of the combat zone, the AN\\/APS-94 airborne radar was developed. Locating

Albert S. White

1960-01-01

49

Signal processor retrofit for air search radar  

NASA Astrophysics Data System (ADS)

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

Miller, Chauncey S.

50

Frequency spectrum change of borehole radar signals and blind separation  

Microsoft Academic Search

Abstract—We model borehole radar signal including a direct wave from a transmitter and a wave reflected from a target by MoM, and we propose a blind separation method to separate the two signals. We modeled the borehole radar signals with MoM, and we will show that power spectrums of a direct wave and reflected waves are different from each other.

Satoshi Ebihara; Masahiro Kiso

2004-01-01

51

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

52

Integrating electromagnetics and signal processing into new radar algorithms  

Microsoft Academic Search

Modern remote sensing applications, including radar, require thoughtful consideration of electromagnetic principles for constructing advanced signal processing algorithms for detection, estimation, tracking, imaging and feature extraction. Starting from a generalized picture of the distributed sensing paradigm, this paper presents current efforts at the Radar Instrumentation Laboratory, Air Force Institute of Technology to develop efficient target models for use in integrated

D. F. Fuller; D. E. Hack; S. Sutara; A. Tempelis; M. Jussaume; M. A. Saville; J. A. Jackson

2011-01-01

53

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

NASA Technical Reports Server (NTRS)

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

Rosen, Paul A.

2012-01-01

54

Introduction to Radar Signal and Data Processing: The Opportunity.  

National Technical Information Service (NTIS)

This paper introduces to the lecture series dedicated to the knowledge-based radar signal and data processing. Knowledge-based expert system (KBS) is in the realm of artificial intelligence. KBS consists of a knowledge base containing information specific...

A. Farina

2006-01-01

55

Digital signal processing in FMCW radar marine tank gauging system  

Microsoft Academic Search

A marine tank gauging system based on the FMCW radar is introduced. The range measurement principle of this system is presented. The digital signal processing procedure based on the FFT is described. The experimental results are also reported

Qi GuoQing

1996-01-01

56

Optical Computing Techniques for Radar and Sonar Signal Processing.  

National Technical Information Service (NTIS)

New applications of the use of coherent optical processing techniques, especially matched spatial filtering and input format control, in radar and sonar signal processing are reviewed. Emphasis is given to specific problems such as long coded waveforms of...

D. Casasent

1977-01-01

57

Synthetic aperture radar signal processing: Trends and technologies  

NASA Technical Reports Server (NTRS)

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

Curlander, John C.

1993-01-01

58

Real-Time Digital Signal Processing of Phased Array Radars  

Microsoft Academic Search

With the advance of hardware and software technology, modern phased array radars are now built with commercial-off-the-shelf (COTS) components, and it opens up a new era in real-time resource scheduling of digital signal processing. This paper targets the essential issues in building a component-oriented signal processor (SP), which is one of the two major modules in modern phased array radars.

Chin-fu Kuo; Tei-wei Kuo; Cheng Chang

2003-01-01

59

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

60

WiMAX signal waveform analysis for passive radar application  

Microsoft Academic Search

WiMAX is the latest globally accepted wireless broadband access standard, which is also a valuable illuminator for passive radar. This paper analyzes the ambiguity function of WiMAX signal to evaluate its suitability as radar waveform. Simulation and experimental results demonstrate that WiMAX signal has a `bed of nails' type ambiguity function, whose properties depend on its frame structure, length of

Qing Wang; Chunping Hou; Yilong Lu

2009-01-01

61

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

62

Intrapulse analysis of radar signal by the use of Hough transform  

Microsoft Academic Search

ELINT\\/ESM type of electronic intelligence in the primary layer uses parameters measurements of intercepted radar signals. Nowadays modern radar uses more and more complex waveforms. Some waveforms are developed intentionally to make their intercept almost impossible. The main distinctive features of modern radar signal are hidden in its time-frequency structure. In the near past the problem of radar signal feature

A. Pieniezny

2008-01-01

63

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

64

FFT Signal processing for non-coherent radar systems  

Microsoft Academic Search

Coherent and non-coherent radar detection of moving targets is analyzed and expressions relating the post-video-detection moving target signal-to-noise ratio to the pre-video-detection moving target signal-to-noise and clutter-to-noise ratios are obtained for non-coherent detection. The effect of processing this resulting real (non-coherent) signal with an FFT processor is then analyzed and compared to the FFT processing of a complex (coherent) signal.

W. Holm; J. Echard

1982-01-01

65

Signal Processing System for the CASA Integrated Project I Radars  

SciTech Connect

This paper describes the waveform design space and signal processing system for dual-polarization Doppler weather radar operating at X band. The performance of the waveforms is presented with ground clutter suppression capability and mitigation of range velocity ambiguity. The operational waveform is designed based on operational requirements and system/hardware requirements. A dual Pulse Repetition Frequency (PRF) waveform was developed and implemented for the first generation X-band radars deployed by the Center for Collaborative Adaptive Sensing of the Atmosphere (CASA). This paper presents an evaluation of the performance of the waveforms based on simulations and data collected by the first-generation CASA radars during operations.

Bharadwaj, Nitin; Chandrasekar, V.; Junyent, Francesc

2010-09-01

66

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

NASA Astrophysics Data System (ADS)

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

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

2004-04-01

67

Analysis of Human Gait Radar Signal Using Reassigned WVD  

NASA Astrophysics Data System (ADS)

Human gait is one of the biological features for human recognition. The key feature of gait can be acquired by analyzing the human echo signal to CW radar. Based on the data from the test CW gait radar, the methods for analyzing multi-component non-stationary signal are discussed in detail. The comparison among the application STFT, WVD, Pseudo-smoothed WVD and its improvements in gait signal are given, and the basic method for gait feature extraction based on time-frequency analysis is proposed. The results in this paper will be a well support for further research.

Zhang, Jun

68

The PARSAX - full polarimetric FMCW radar with dual-orthogonal signals  

Microsoft Academic Search

The article describes the IRCTR PARSAX radar system - fully polarimetric FMCW radar with dual-orthogonal sounding signals, which has the possibility to measure all elements of the radar targets polarization scattering matrix simultaneously, in one sweep.

Oleg A. Krasnov; Leo P. Ligthart; Zhijian Li; Pidio Lys; Fred van der Zwan

2008-01-01

69

The radar simulator: deriving the radar signal using the cloud model output  

Microsoft Academic Search

We present an approach to simulate cloud radar signals on the basis of cloud model output, the radar simulator. The simulator is being developed to aid validation of the cloud model. The cloud model applies double-moment bulk warm-rain and ice schemes developed by Morrison and Grabowski.1, 2 As an input, the simulator uses profiles of the mixing ratios and number

Aleksandra E. Kardas; Sally McFarlane; Hugh Morrison; Jennifer Comstock; Wojciech W. Grabowski; Szymon P. Malinowski

2009-01-01

70

Millimeter Wave Radar for detecting the speech signal applications  

Microsoft Academic Search

MilliMeter Wave (MMW) Doppler Radar with grating structures for the applications of detecting speech signals has been discovered in our laboratory. The operating principle of detection the acoustic wave signals based on the Wave Propagation Theory and Wave Equations of The ElectroMagnetic Wave (EMW) and Acoustic Wave (AW) propagating, scattering, reflecting and interacting has been investigated. The experimental and observation

Zong-Wen Li

1996-01-01

71

Digital Signal Processor for Doppler Radar Sensing of Vital Signs.  

National Technical Information Service (NTIS)

A digital signal processor for Doppler radar sensing of vital signs is described. 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 hea...

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

2001-01-01

72

Statistical Properties of Signals in Radar Monopulse Amplitude Type Installations.  

National Technical Information Service (NTIS)

There is derived a probability density function (p. d. f.) of an amplitude type monopulse radar system output signal. It is supposed that the receivers input signals consist of an hormonic oscillation with unknown initial phase and of additive gaussian no...

J. Kulikowski

1966-01-01

73

Examples of a Class of Chaotic Radar Signals.  

National Technical Information Service (NTIS)

This note is a preliminary study of radar signals viewed as discretised nonlinear dynamical systems. Motivated by Haykin and Li 1995, a class of recursively defined signals is introduced, and two specific examples are considered. It will be shown that suc...

G. V. Weinberg A. Alexopoulos

2005-01-01

74

MIMO radar signal processing for distributed phased arrays  

Microsoft Academic Search

We explore transmit signaling and receive signal processing strategies for a notional MIMO radar system consisting of widely distributed phased arrays. The assumptions are that within a phased array, there is a fixed rigid geometry and perfect phase synchronization, and there is a single look at the target. In constrast, between phased arrays there is imperfect phase synchronization and multiple

Daniel R. Fuhrmann

2011-01-01

75

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

76

Hybrid optical\\/electronic signal processor for laser radar signals in fire control systems  

Microsoft Academic Search

This paper reports on the development of a hybrid optical\\/electronic signal processor for laser radar signals in fire control applications. The breadboard system being developed consists of three subsystems: (1) a signal generator producing target-representative signals, (2) the signal processor consisting of a radiometric channel and a Doppler channel, and (3) a data acquisition, analysis, and display subsystem. The radiometric

George B. Findley; Christopher S. Anderson; Sandi K. Tepper; Michael J. Pascale; Lee V. Watson; Howard A. Jenkinson

1992-01-01

77

Windshear detection radar signal processing studies  

NASA Technical Reports Server (NTRS)

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

Baxa, Ernest G., Jr.

1993-01-01

78

Frequency-agile radar signal processing  

Microsoft Academic Search

Analytical and simulation methods are used to determine the balance between coherent and incoherent integration which yields the greatest SNR improvement in a block-to-block frequency-agile radar. Emphasis is placed on a model using peak selection of FFT Doppler channels and is compared to a reference model involving only a single Doppler channel. It is shown that the choice of block

W. M. Waters; G. J. Linde

1979-01-01

79

Tensor algebra and multidimensional harmonic retrieval in signal processing for MIMO radar  

Microsoft Academic Search

Detection and estimation problems in multiple-input multiple-output (MIMO) radar have recently drawn considerable interest in the signal processing community. Radar has long been a staple of signal processing, and MIMO radar presents challenges and opportunities in adapting classical radar imaging tools and developing new ones. Our aim in this article is to showcase the potential of tensor algebra and multidimensional

Dimitri Nion; Nicholas D. Sidiropoulos

2010-01-01

80

Random signal radar - a winner in both the military and civilian operating environments  

Microsoft Academic Search

Besides some general requirements, modern military radars should possess excellent LPI (low probability of intercept) properties. And civilian radars should satisfy the rigorous requirement of EMC (electro-magnetic compatibility) performance. The special features of random signal radar are analyzed here based on the different requirements for military and civilian use. Results show that random signal radar has excellent LPI property and

Guo-Sui Liu; Hong Gu; Wei-Min Su; Hong-Bo Sun; Jian-Hui Zhang

2003-01-01

81

Test Results of the Signal Processing and Amplifier Unit for the Emittance Measurement System.  

National Technical Information Service (NTIS)

The signal processing and amplifier unit for the emittance measurement system is the unit with which the beam current on the harp-wires and the slit is measured and converted to a digital output. Temperature effects are very critical at low currents and t...

L. Stawiszynski S. Schneider

1984-01-01

82

Deciphering fluorescence signals by quantifying separately the excitation intensity from the number of emitters  

NASA Astrophysics Data System (ADS)

Conventional fluorescence detection is sensitive to an intricate product of the number of fluorescent emitters times the local excitation intensity. Here, we describe a method to locally quantify the excitation intensity and the number of emitters separately, enabling a clear distinction between the phenomena responsible for a given fluorescence signal. Our technique is based on harmonic excitation modulation and higher-order fluorescence demodulation. It is compatible with a wide range of observations, opening new characterization routes for fluorescence detection or imaging on complex systems, such as plasmonic substrates or scattering media.

Hostein, Richard; Aouani, Heykel; Rigneault, Hervé; Wenger, Jérôme

2011-09-01

83

Deciphering fluorescence signals by quantifying separately the excitation intensity from the number of emitters.  

PubMed

Conventional fluorescence detection is sensitive to an intricate product of the number of fluorescent emitters times the local excitation intensity. Here, we describe a method to locally quantify the excitation intensity and the number of emitters separately, enabling a clear distinction between the phenomena responsible for a given fluorescence signal. Our technique is based on harmonic excitation modulation and higher-order fluorescence demodulation. It is compatible with a wide range of observations, opening new characterization routes for fluorescence detection or imaging on complex systems, such as plasmonic substrates or scattering media. PMID:21886196

Hostein, Richard; Aouani, Heykel; Rigneault, Hervé; Wenger, Jérôme

2011-09-01

84

High Resolution Spectrum Estimation of FMCW Radar Signals  

Microsoft Academic Search

This paper presents a comparative study of high resolution spectral estimation methods applied to Frequency Modulated Continuous Wave (FMCW) radar data; autoregressive (AR), Prony, and, Eigenanalysis-based methods are briefly reviewed. A comparison of spectral lines detection capabilities between methods for different signal to noise ratio (SNR) and modal amplitudes is made using numerical experiments. Computer simulations have been made using

Michel Bouchard; D. Gingras; Y. de Villers; D. Potvin

1994-01-01

85

Sub-?W signal power doppler radar heart rate detection  

Microsoft Academic Search

Periodic motion, such as that resulting from cardiopulmonary activity, can be measured by direct-conversion microwave Doppler radar. In such systems, motion is measured as phase modulation and measurement sensitivity is significantly affected by phase noise and amplitude modulation sidebands in the local oscillator. Presented here are experimental results of heart rate measurements under various signal output power conditions, with consideration

Shuhei Yamada; Mingqi Chen; Victor Lubecke

2006-01-01

86

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

87

Signal processing techniques for maritime surveillance with skywave radar  

Microsoft Academic Search

Detection and tracking of maritime targets using skywave radar is influenced by the propagation medium, interference environment and target scenario. Acquired data display distortion, fading, non-stationarity, and heterogeneity. Brief examples of data are given, then signal processing techniques are developed to provide robust adaptive Doppler processing, rejection of impulsive noise, improved CFAR using the Weibull distribution with robust two-parameter estimation,

Mike D. E. Turley

2008-01-01

88

Digital processing system of the radar echo-signals  

NASA Astrophysics Data System (ADS)

A PC-based system for the digital processing of radar echo signals is described. The proposed system, involving user-level interactive RSAS, is implemented on a PC-based digital processing system compatible with the IBM-XT. Both hardware and software features are considered.

Giryn, Andrzej

89

Bistatic noise radar using locally generated reference signal  

Microsoft Academic Search

In the paper a bistatic noise radar for moving target detection is considered. The main focus is generation of the reference signal at the receiver site, its calibration, and time and frequency synchronization. In the paper the results of real-life experiment proving the concept are presented. 1. Introduction In the paper we deal with a continuous-wave bistatic (in general multistatic)

Mateusz Malanowski; Pawel Roszkowski

2011-01-01

90

INTRODUCTION TO RADAR SIGNAL & DATA PROCESSING : THE OPPORTUNITY  

Microsoft Academic Search

1. SUMMARY This paper introduces to the lecture series dedicated to the knowledge-based radar signal and data processing. Knowledge-based expert system (KBS) is in the realm of artificial intelligence. KBS consists of a knowledge base containing information specific to a problem domain and an inference engine that employs reasoning to yield decisions. KBS have been built: some are very complex

A. Farina

91

A new technique in passive coherent radar signal processing  

Microsoft Academic Search

In this paper, we focus on adaptive and wavelet based systems in radar signal processing, and a new algorithm to Doppler compensation is developed. The new wavelet-based method for ambiguity surface smoothing that applies the three dimensions dual tree wavelet transform and adapt constant false alarm rate, is proposed. The model captures the dependence between a wavelet coefficient and its

Mostafa Borhani; Vafa Sedghi; Mohammad Mahdi Nayebi

2005-01-01

92

Multicarrier Coherent Pulse Shaping for Radar and Corresponding Signal Processing  

Microsoft Academic Search

A new pulse shaping approach based on coherent superposition of multiple carriers in radar is introduced, by which a shorter efficient pulse width waveform can be formed. At the receiver end, breaking the echo into multiple corresponding frequency components, multiple series can be taken from those individual components, then recombining these components to achieve the signal processing gain. Three processing

Duan Junqi

2007-01-01

93

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

94

Correlation properties of Gaussian FSK\\/PSK radar signals  

Microsoft Academic Search

Hybrid radar signals which are simultaneously frequency-shift-keyed (FSK) and phase-shift-keyed (PSK) are investigated with regard to their range correlation properties. The firing order of the discrete frequencies within a single burst is selected at random from a pseudo-Gaussian distribution. The range correlation properties of FSK and FSK\\/PSK signals are illustrated using computer simulations of the autocorrelation functions of several representative

B. Jeffrey Skinner; J. Patrick Donohoe; Franklin M. Ingels

1993-01-01

95

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

Microsoft Academic Search

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

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

2002-01-01

96

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

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

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

97

High resolution radar tomographic imaging using single-tone CW signals  

Microsoft Academic Search

Radar tomographic imaging is a special radar imaging technique which can achieve very high spatial resolution (up to ¼ wavelength) but with very narrow signal bandwidth. Although the theory of radar tomography had been developed for more than 20 years, very few experimental results can be found in public literatures. In this paper, the radar tomographic imaging is investigated and

Hongbo Sun; Hongchuan Feng; Yilong Lu

2010-01-01

98

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

99

Target material characterization using high-order signal processing of ultra-wideband radar data  

Microsoft Academic Search

Results obtained by two high-order signal processing methods applied to ultrawideband (UWB) radar data in the UHF band are described. The UWB radar data were collected in a specially designed bistatic test range. Four types of UWB signals were used to test a metal (reference) plate, five different commercially available radar absorbing material samples with metal backing, and five natural

Vasilis Z. Marmarelis; David Sheby; Elizabeth C. Kisenwether; Todd A. Erdley

1992-01-01

100

High Resolution Radar Signal Processor for Isar and Automatic Target Recognition  

Microsoft Academic Search

This paper describes a radar signal processor architecture suitable for implementing monopulse high resolution radar (HRR). A coherent transmitter and receiver radar is used to transmit and process waveforms with long pulse widths and high-bandwidth properties. The received signals are YQ demodulated, sampled and processed using a digital filter matched to the transmitted waveform. The output of the processor is

L. J. Sciaccat; R. J. Evans

1996-01-01

101

Attenuation rates of coastal radar signals at 25 MHz  

NASA Astrophysics Data System (ADS)

The attenuation rate of the ground wave signal with range is a factor limiting the performance of coastal radars. It is shown that observed attenuation rates are less than theoretically predicted rates at 25 MHz. This result, contrary to earlier findings at lower frequencies, suggests the onset of tropospheric ducting above 20 MHz. The attenuation rates for various sea states and distances are tabulated to allow estimates of system performance near 25 MHz.

Lyons, R. S.; Barrick, D. E.

1984-02-01

102

Chaotic Signals with Weak-Structure Used for High Resolution Radar Imaging  

Microsoft Academic Search

Recently, signals generated via chaotic maps for radar imaging have been studied. Chaotic signals are easy to be generated and applied, but not all chaos-based signals are suited for high resolution radar imaging. The autocorrelation and ambiguity functions of many chaos-base modulated signals are poor, so they aren't suited for radar imaging. Up to now, there has no reference to

Chen Bin; Tang Jun; Zhang Yong; Cai Peng; Huang Jian; Huang Guo Qiang

2009-01-01

103

Digital Radar-Signal Processors Implemented in FPGAs  

NASA Technical Reports Server (NTRS)

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

Berkun, Andrew; Andraka, Ray

2004-01-01

104

The radar simulator: deriving the radar signal using the cloud model output  

NASA Astrophysics Data System (ADS)

We present an approach to simulate cloud radar signals on the basis of cloud model output, the radar simulator. The simulator is being developed to aid validation of the cloud model. The cloud model applies double-moment bulk warm-rain and ice schemes developed by Morrison and Grabowski.1, 2 As an input, the simulator uses profiles of the mixing ratios and number concentrations of cloud droplets, rain/drizzle drops, and ice crystals, as well as the air temperature. For the ice crystals, the rimed mass fraction predicted by the ice scheme is also used. The simulator applies precomputed look-up tables containing scattering properties of cloud and precipitation particles, such as reflectivities, extinction and absorption coefficients. For each grid point, the coefficients are integrated over particle size distributions and summed over hydrometeor types. Consistent with assumptions in the cloud model microphysical scheme, modified gamma size distributions are assumed for cloud droplets and ice crystals, whereas the exponential Marshall-Palmer size distribution is assumed for the rain/drizzle drops. Application of the radar simulator to a simulation of clouds observed during the TWP-ICE campaign over northern Australia is presented.

Kardas, Aleksandra E.; McFarlane, Sally; Morrison, Hugh; Comstock, Jennifer; Grabowski, Wojciech W.; Malinowski, Szymon P.

2009-09-01

105

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

106

A multi-DSP signal processing and control system for MST radar  

Microsoft Academic Search

Atmospheric remote sensing by Doppler radar is an increasingly used technique. An MST radar is an instrument that can be used for mesosphere, stratosphere and troposphere remote sensing. This paper describes a signal processing and control system for atmospheric sounding radars, with improved characteristics with respect to formerly used architectures. The authors refer especially to wind profiling as an important

Martin F. Sarango; Ronald F. Woodman; Enrico Ragaini; Edilberto H. Vasquez

1995-01-01

107

Identification of LPI Radar Signal Modulation using Bi-coherence Analysis and Artificial Neural Networks Techniques  

Microsoft Academic Search

This paper presents Higher Order Spectral Analysis (HOSA) and Artificial Neural Network techniques for identification of LPI (Low Probability of Intercept) Radar signal. Common Spectral analysis and conventional methods fail to detect low powered emissions of LPI Radars and even normal radars in noisy environments. This leads us to use Higher Order Spectral Analysis (HOSA) techniques (bi-spectrum, bi-coherence etc.,) enabling

L. Anjaneyulu; N. S. Murthy; N. V. S. N. Sarma

2009-01-01

108

SIGNAL PROCESSING FOR TARGET MOTION ESTIMATION AND IMAGE FORMATION IN RADAR IMAGING OF MOVING TARGETS  

Microsoft Academic Search

Radar imaging of moving targets is often called ISAR (In- verse Synthetic Aperture Radar.) Imaging of moving targets generally consists of two separate tasks: Estimation and cor- rection of target motion, and the explicit image formation. Both tasks must be implemented with great care, as it is the coherent processing of the received radar signal phase that makes imaging possible.

Trygve Sparr

2006-01-01

109

Ambiguity Functions for Monostatic and Bistatic Radar Systems using UWB Throb Signal  

Microsoft Academic Search

Waveform design and ambiguity function are significant tools for the performance analysis of radar systems. We first describe the principle of waveform design for ultrawideband (UWB) impulse waveforms and present the signal model and the advantages of a UWB-throb signal. The ambiguity function of the UWB-throb signal for monostatic radar is derived in detail and analyzed by computer simulation to

Malek G. M. Hussain

2011-01-01

110

Synthetic aperture radar signal processing on the MPP  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

111

Signal processing software for ground penetrating radar, user's manual  

NASA Astrophysics Data System (ADS)

This is the user's manual for the signal processing software for reducing ground penetrating radar (GPR) data. The manual provides background information and instructions for operating the computer program. The developed program is based on the synthetic aperture focusing technique. Input data to the program consists of digitized sequential GPR scans from a linear survey. The format for the input data is specified in Appendix C. The output of the program are two-dimensional plots of the ground profile showing the stations and depth of the objects identified by the program. Features of the program include utilities to determine the velocity of propagation of the GPR signal and the location of the ground surface as well as semi-automatic and automatic processing of the data. The program is designed to operate on an IBM PC or compatible computer. Other hardware and supporting software requirements for operating the program are specified in Appendix B.

Liem, Ronnie; Davis, Thomas J.

1988-03-01

112

Experimental investigations of digital signal processing techniques in an FMCW radar for naval application  

Microsoft Academic Search

Recently we have observed increased interest in frequency modulated continuous wave (FMCW) radars, mainly because of their low probability of intercept (LPI) properties. In such radars the information on range of targets appears in the frequency domain and it is obtained on the basis of spectrum analysis carried out for a so called beat signal. The beat signal is a

A. Grzywacz

2002-01-01

113

Sparse Detection in the Chirplet Transform: Application to FMCW Radar Signals  

Microsoft Academic Search

This paper aims to detect and characterize a signal coming from frequency modulation continuous wave radars. The radar signals are made of piecewise linear frequency modulations. The maximum chirplet transform (MCT), a simplification of the chirplet transform is proposed. A detection of the relevant maximum chirplets is proposed based on iterative masking, an iterative detection followed by window subtraction that

Fabien Millioz; Michael Davies

2012-01-01

114

On Mary Sequential Hypothesis Testing for the Classification of Radar Signals  

Microsoft Academic Search

This paper is concerned with the performance of M-ary sequential hypothesis tests applied to the classification of radar signals. This investigation is primarily motivated by interest in the design of radar target identification (RTI) systems, where the decision algorithm produces the identity, among M possibilities, based upon several observations of vectors of signal parameters. The performance of several M-ary sequential

F. D. Garber; I. Jouny

1987-01-01

115

Application of Radar Signal Processing System Based on DSP in the VTS  

Microsoft Academic Search

Radar signal processing system is an important part of vessel traffic services. In order to overcome the shortcomings of traditional analog video system, this paper proposes a design solution for digital radar signal processing system based on DSP and a new method that is a constant false alarm rate algorithm based on wavelet transform. This method can suppress the interference

Shuang Xu; Jiyin Zhao; Jidong Suo

2009-01-01

116

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

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

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

117

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

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

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

118

Development of a chaotic signal radar system for vehicular collision-avoidance  

Microsoft Academic Search

The paper describes the development of a new type of radar system called Chaotic Signal Radar (CSR), which utilises truly random signals for the modulation and a novel implicit sampling averaging algorithm in the receiver. The paper presents the results of simulation study in conjunction with the real measurements using a prototype CSR.

Yoshihisa Hara; Teruyuki Hara; Takashi Seo; Hajime Yanagisawa; Paul Ratliff; Wojciech Machowski

2002-01-01

119

Phase coherence and Signal-To-Noise ratio considerations for sampled aperture radar systems  

Microsoft Academic Search

This report describes the application of Sampled Aperture Radar (SAMPAR) technology to the tracking of low-angle targets of low-angle targets at sea. In particular, expressions are developed and presented describing aperture signals for a conventional (SAMPAR) configuration which uses coherent local oscillators. The radar signals are shown to contain an interference term in which is contained all of the information

J. Litva; H. C. Chan

1987-01-01

120

A new technique for Doppler frequency analysis of radar signals  

NASA Astrophysics Data System (ADS)

A longstanding performance goal for Army ground surveillance radars is the automatic classification of moving ground targets on the battlefield. Limited classification has been achieved by splitting the radar Doppler spectrum into lower and higher frequency bands, thus distinguishing between targets having different radial velocities. While this is an important feature, since only certain targets (vehicles) are capable of obtaining high radial speeds, it does not provide a distinction between a moving man and vehicles having low radial speed components. That there are distinct differences in the Doppler signatures between man and vehicle is easily established by listening to typical Doppler return signals. One can clearly distinguish the step modulation of a walking man from the relatively constant or slowly changing tone of a vehicle. As to be expected, a spectrogram of a walking man shows this repetitive behavior. Most obvious is a sinewave like frequency modulation at the step frequency of the main body return power appearing as a black band near 100 Hertz. This oscillatory temporal characteristic in the Doppler shifted frequency is practically never seen in vehicular return and is the discriminant chosen for automatic classification.

Rittenbach, O. E.

1980-06-01

121

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

122

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

123

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

124

Signaling Strategies for the Hybrid MIMO Phased-Array Radar  

Microsoft Academic Search

The hybrid MIMO phased array radar (HMPAR) is a notional concept for a multisensor radar architecture that combines elements of traditional phased-array radar with the emerging technology of multiple-input multiple output (MIMO) radar. A HMPAR comprises a large number, MP, of T\\/R elements, organized into M subarrays of P elements each. Within each subarray, passive element-level phase shifting is used

Daniel R. Fuhrmann; J. Paul Browning; Muralidhar Rangaswamy

2010-01-01

125

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

126

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

127

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

128

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

PubMed

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

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

2014-01-01

129

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

NASA Astrophysics Data System (ADS)

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 a look-down radar, which calls for a thumbtack ambiguity function. Since a small radar cross section in this application is typically due to the small size of the target that is coated with absorbing material, the antistealth feature of the nonsinusoidal radar is implicitly being used. The principle is presented of a resolution function (tentatively called the range-velocity or the range-Doppler resolution function) based on processing a nonsinusoidal signal consisting of N characters with a time separation TD and each character consisting of a sequence of L binary pulses of duration T. It is shown that range-velocity resolution functions approaching the ideal thumbtack function are easy to obtain. The blind speeds of the pulse-Doppler radar with sinusoidal carrier do not inherently occur, and all velocities are observed as true velocities rather than as velocities modulo the first blind speed (velocity ambiguity).

Mohamed, Nasser J.

1990-05-01

130

FPGA based signal processing module design and implementation for FMCW vehicle radar systems  

Microsoft Academic Search

In this paper, we design the signal processing module based on FPGA for vehicle FMCW radar systems. We employ the detection algorithms based on two-step FFT (Fast Fourier Transform) using the several fast ramps in order to resolve radar range-velocity ambiguities. We implement the detection algorithms including the first FFT, DBF (Digital Beam Forming), the second FFT, and CFAR (Constant

Eugin Hyun; Sang-Dong Kim; Yeong-Hwan Ju; Jong-Hun Lee; Eung-Noh You; Jeong-Ho Park; Dong-Jin Yeom; Sang-Hyun Park; Seung-Gak Kim

2011-01-01

131

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

132

Characterization of Noise Technology Radar (NTR) Signal Detectability Using a Non-Cooperative Receiver.  

National Technical Information Service (NTIS)

As Noise Technology Radar (NTR) systems emerge, there is a need for non-cooperative, non-matched filter detection and exploitation. This work is based on that need and AFIT's Noise Network (NoNET) radar system. These signals are associated with Low Probab...

D. V. Atienza

2011-01-01

133

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

NASA Technical Reports Server (NTRS)

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.

1991-01-01

134

Radar principles  

Microsoft Academic Search

The basic operating principles, design, and applications of radars are discussed in an introductory text intended for first-year graduate students. Topics addressed include radar measurements, radar target cross sections, radar detection, ground effects, matched filters, ambiguity functions, coded radar signals, and radar measurement accuracy. Consideration is given to processing coherent pulse trains, moving-target indicators, CFAR, SAR, and monopulse antenna tracking.

Nadav Levanon

1988-01-01

135

Optimal Signal Processing of Frequency-Stepped CW Radar Data  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

136

Optimal Signal Processing of Frequency-Stepped CW Radar Data  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

137

The Signal Digital Processing in the Millimeter Band FMCW Radar  

Microsoft Academic Search

The frequency-modulated continuous wave-radars - (FMCW-radars) are widely applied in the car road safety systems, the aircraft altimeters, the fusion plasma microwave diagnostics and in other ranging systems of different usage. The most optimal choice in terms of the \\

A. V. Varavin; G. P. Ermak; A. S. Vasilev; I. V. Popov

2007-01-01

138

Sparse Signal Methods for 3-D Radar Imaging  

Microsoft Academic Search

Synthetic aperture radar (SAR) imaging is a valuable tool in a number of defense surveillance and monitoring applica- tions. There is increasing interest in 3-D reconstruction of objects from radar measurements. Traditional 3-D SAR image formation requires data collection over a densely sampled azimuth-elevation sector. In practice, such a dense measurement set is difficult or impossible to obtain, and effective

Christian D. Austin; Emre Ertin; Randolph L. Moses

2011-01-01

139

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

140

Implementation of a parallel signal processing system for all-purpose radar  

Microsoft Academic Search

A DSP-based all-purpose radar parallel signal processing system (RPSPS) with high-speed real-time signal processing is implemented to fulfil the all-purpose radar system reconfiguration. High performance DSP chips are used as the kernel processing nodes. By means of local shared memory, a global distributed memory parallel system and the pipelined dataflow method, it can perform absolutely parallel data processing of multi

Li Ming; Wu Yan; Shun-jun Wu; Yuan Wei-ming

2002-01-01

141

Doppler radar having phase modulation of both transmitted and reflected return signals  

NASA Technical Reports Server (NTRS)

A microwave radar signal is generated for transmission through an antenna. Before transmission, the signal is phase modulated by 0 deg or 90 deg amounts during each alternate half-cycles of an intermediate frequency (IF) clock signal. After transmission and return, the signal is again phase modulated the same amounts during each alternate half-cycles. The return phase modulated signal is mixed with a leakage signal component of the microwave signal, leaving an IF Doppler. The IF Doppler signal may then be amplified, removing any requirement that direct current level signals be amplified and also removing the effect of detector noise from the Doppler signal.

Kobayashi, H. S.; Shores, P. W.; Rozas, P. (inventors)

1984-01-01

142

Determination of the Best Ground Penetrating Radar Source Signal Type for the Accurate Location of Underground Utilities.  

National Technical Information Service (NTIS)

This investigation was to determine the best ground-penetrating radar (GPR) source signal applicable for locating underground utilities and other construction obstacles. Four types of GPR systems were tested: Two time-domain short-pulse radars, one swept ...

W. E. Thain

1988-01-01

143

A 77GHz FMCW radar transceiver sourced through a 19GHz SiGe Colpitts oscillator  

Microsoft Academic Search

An integrated 19-GHz Colpitts oscillator for a 77-GHz FMCW automotive radar frontend application is presented. The Colpitts oscillator has been realized in a fully differential circuit architecture. The VCO's 19 GHz output signal is buffered with an emitter follower stage and used as a LO signal source for a 77-GHz radar transceiver architecture. The LO frequency is quadrupled and amplified

Florian Starzer; Hans Peter Forstner; Christoph Wagner; Alexander Fischer; H. Jager; D. Kissinger; A. Stelzer

2009-01-01

144

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

NASA Technical Reports Server (NTRS)

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

Baxa, Ernest G., Jr.

1992-01-01

145

Detection and segmentation of fmcw radar signals based on the chirplet transform  

Microsoft Academic Search

In this paper we present a algorithm designed to detect and characterise the signal coming from Frequency Modulation Continuous Wave radars. The signals are made of linear frequency modulations. A few relevant coefficients of the chirplet transform are selected, and then gathered into chirps whose starting time, length, and chirprate are estimated. An example is provided on a synthetic signal.

Fabien Millioz; Michael E. Davies

2011-01-01

146

Radar Detection and Classification of Jamming Signals Belonging to a Cone Class  

Microsoft Academic Search

This paper considers the problem of detecting and classifying a radar target signal and a jamming signal produced by a deception electronic counter measure (ECM) system based on a digital radio frequency memory (DRFM) device. The disturbance is modeled as a complex correlated Gaussian process. The jamming is modeled as a signal belonging to a cone whose axis is the

Maria Greco; Fulvio Gini; Alfonso Farina

2008-01-01

147

Radar - Principles, technology, applications  

NASA Astrophysics Data System (ADS)

An overview of modern radar is presented. The topics addressed include: functions and parameters of the radar system, the radar equation, targets and interfering signals, target echo information extraction, tracking radar, radar transmitters and microwave components, radar antennas, receivers and displays, radar signal processing, high resolution radar.

Edde, Byron

148

Autonomous Non-Linear Classification of LPI Radar Signal Modulations.  

National Technical Information Service (NTIS)

In this thesis, an autonomous feature extraction algorithm for classification of Low Probability of Intercept (LPI) radar modulations is investigated. A software engineering architecture that allows a full investigation of various preprocessing algorithms...

T. O. Gulum

2007-01-01

149

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

150

Radar signal pre-processing to suppress surface bounce and multipath  

DOEpatents

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

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

2013-12-31

151

M3: A high performance signal processor for RADAR applications  

Microsoft Academic Search

Real time radar computing requires high processing performances and fast and efficient I\\/O capabilities. These goals have been achieved by means of a new multiprocessor architecture based on the Motorola DSP 96002. This system was developed entirely in the FIAR laboratories, and now is a state-of-the-art unit in their avionic radar family. The authors describe a computer system developed specifically

D. Camerani; M. Monacchi; R. Morbio

1993-01-01

152

Cross-correlation analysis of noise radar signals propagating through lossy dispersive media  

NASA Astrophysics Data System (ADS)

Correlation detection is an essential ingredient in noise radar. Such detection is achieved via coherent signal processing, which, conceivably, gives the best enhancement in the signal-to-noise ratio. Over the years, much research and progress has been made on the use of noise radar systems as means for effective through-wall detection. Information about a particular target's range and/or velocity are often acquired by comparing and analyzing both transmit and received waveforms. One of the widely used techniques employed to measure the degree of similarity between the two signals is correlation. The aforementioned methodology determines to what extent two waveforms match by multiplying and shifting one signal with respect to a time-lagged version of the second signal. This feature of correlation is very applicable to radar signals since a received signal from a target is delayed on the path of return to the receiving antenna. Transmission and reflection impairments will distort the propagating signals and degrade the correlation. Thus, it is essential that we try to study the effects that such degradations can have on the signals that will be used in the correlation process. This paper presents some concepts of a noise radar system, simulation studies, and an analysis of the results ascertained.

Smith, Sonny; Narayanan, Ram M.

2011-05-01

153

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

154

Radar  

Microsoft Academic Search

Over 1,000,000 km2 of the equatorial surface of Mars west of the Arsia Mons volcano displays no 3.5-cm radar echo to the very low level of the radar system noise for the Very Large Array; the area displaying this unique property has been terms \\

James R. Zimbelman; Kenneth S. Edgett

1994-01-01

155

A parameter extraction technique for FMCW radar signals using Wigner-Hough-Radon transform  

Microsoft Academic Search

An autonomous parameter extraction algorithm for frequency modulated continuous wave (FMCW) radar signals using Wigner-Ville Distribution (WVD)-Hough transform was investigated in [1] and extraction of polyphase radar modulation parameters using a Wigner-Ville distribution-Radon transform was investigated in [2]. The algorithm in [1] produced very dependable results with as low as ?6 dB SNR levels, however some degradation has been observed

T. O. Gulum; A. Y. Erdogan; T. Yildirim; P. E. Pace

2012-01-01

156

Parameter extraction of FMCW modulated radar signals using Wigner-Hough transform  

Microsoft Academic Search

In this study, an autonomous parameter extraction algorithm for frequency modulated continuous wave (FMCW) radar signals using Wigner-Hough transform is investigated. The algorithm can be applied to other low probability of intercept (LPI) radar waveforms as well. The proposed method uses the Pseudo-Wigner-Ville Distribution (PWVD) as a time-frequency (T-F) detection technique and Hough Transform (HT) to identify the parameters of

Taylan Ozgur Gulum; Ahmet Yasin Erdogan; Tulay Yildirim; Lutfiye Durak Ata

2011-01-01

157

Application of Bispectrum Estimation for Time-Frequency Analysis of Ground Surveillance Doppler Radar Echo Signals  

Microsoft Academic Search

A microwave coherent homodyne and polarimetric ground surveillance Doppler radar is employed for collecting the radar returns from moving objects. Nonstationary nonlinearly frequency-modulated and multicomponent backscattered signals are analyzed and described as a sum of Doppler frequency-shifted polynomial chirp-like components. Instantaneous frequencies corresponding to the radiation backscattered by the different parts of a moving spatially distributed object are extracted from

Jaakko T. Astola; Karen O. Egiazarian; Grigory I. Khlopov; Stanislav I. Khomenko; Igor V. Kurbatov; Vladimir Ye. Morozov; Alexander V. Totsky

2008-01-01

158

Real-time signal processing system for high resolution CWLFM millimeter-wave radars  

Microsoft Academic Search

An FPGA-based real-time signal processing unit has been developed to perform Doppler processing in a high resolution CWLFM (continuous wave linear frequency modulated) millimeter-wave radar demonstrator. The article focuses on the strategies followed in order to achieve the required throughput as well as on the measures taken to guarantee coherency. Doppler processing is accomplished to output Range-Doppler radar images and

Javier Carretero Moya; Wang Zongbo; Álvaro Blanco del Campo; Javier Gismero Menoyo; Alberto Asensio López

2008-01-01

159

Comparison of antenna dispersion and digital signal processing effects in ultrawideband Ground Penetrating Radar systems  

NASA Astrophysics Data System (ADS)

In Ground Penetrating Radar it is of great interest to have a pulse width as narrow as possible to achieve best resolution capability. However, ultrawideband antennas may cause distortion to the radar signal due to dispersion, which is dependent on the frequency and bandwidth, as well as the direction of radiation. As dispersion causes an increase of the peak's width, the resolution capability is degraded.

Seyfried, Daniel; Brueckner, Sebastian; Schoebel, Joerg

2014-02-01

160

Reliability of signal processing technique for pavement damages detection and classification using ground penetrating radar  

Microsoft Academic Search

Ground penetrating radar (GPR) signal processing is a nondestructive technique, currently performed by many agencies involved in road management and particularly promising for soil characteristics interpretation. The focus of this paper is to assess the reliability of an optimal signal processing algorithm for pavement inspection. Preliminary detection and subsequent classification of pavement damages, based on an automatic GPR analysis, have

Andrea Benedetto; Francesco Benedetto; Maria Rosaria De Blasiis; Gaetano Giunta

2005-01-01

161

Noncircular waveforms exploitation for Radar Signal processing: Survey and study for agile radar waveform  

Microsoft Academic Search

With new generation of Active Digital Radar Antenna, there is a renewal of waveform generation and processing approaches, and new strategies can be explored to optimize waveform design and waveform analysis and to benefit of all potential waveform diversity. Among these strategies, building and exploitation of the Noncircularity of waveforms is a promising issue. Up to the middle of the

F. Barbaresco; P. Chevalier

2009-01-01

162

Signal modeling and processing for physiological sensing through UWB radars  

Microsoft Academic Search

A very promising application of Ultra Wide-Band radar technology is the continuous monitoring of some physiolog- ical parameters, like those relevant to the breath and heartbeat activity, without the need of any invasive tool neither of any contact with the subject under analysis. This idea has already appeared in the literature since some time, but its practical feasibility and assessment

Marco Baldi; Franco Chiaraluce; Matteo Moretti; Francesco Venieri; Blerina Zanaj

2011-01-01

163

Generating nonlinear FM chirp radar signals by multiple integrations  

DOEpatents

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

Doerry, Armin W. (Albuquerque, NM) [Albuquerque, NM

2011-02-01

164

Phase noise in two-dimensional spectrum of video signal in FMCW homodyne radar  

Microsoft Academic Search

Mapping of transmitted signal phase noise into amplitude spectra of a video signal in a frequency-modulated continuous wave homodyne radar with two-dimensional signal processing is studied for the example of an ideal stationary object and a free-running oscillator. Results of numerical simulations for a flicker FM noise-dominated source are given and discussed. Closed form analytical expressions for components of differential

Miroslaw E. Adamski; Knysztof S. Kulpa; M. Nalecz; Andrzej Wojtkiewicz

2000-01-01

165

Quantization noise in digital signal processing by harmonic analysis in a synthetic-aperture radar  

Microsoft Academic Search

The paper derives and analyzes expressions for assessing the effect of quantization noise arising in digital signal processing by harmonic analysis in a synthetic-aperture radar on the output signal for an arbitrary weight function in an FFT processor. The output signal-to-noise ratio is shown to depend on the FFT base size, the digit-representation length in the processing system, and the

N. A. Sazonov

1985-01-01

166

A note on the use of coherent integration in periodogram analysis of MST radar signals  

NASA Astrophysics Data System (ADS)

The effect of coherent integration on the periodogram method to estimate the power spectra of MST radar signals is examined. The spectrum estimate usually is biased, even when care is taken to reduce the aliasing effects. Due to this bias, the signal power for Doppler shifted signals is underestimated by as much as 4 dB. The use of coherent integration in reducing the effect of aliased power line harmonics is pointed out.

Rastogi, P. K.

1983-12-01

167

A note on the use of coherent integration in periodogram analysis of MST radar signals  

NASA Technical Reports Server (NTRS)

The effect of coherent integration on the periodogram method to estimate the power spectra of MST radar signals is examined. The spectrum estimate usually is biased, even when care is taken to reduce the aliasing effects. Due to this bias, the signal power for Doppler shifted signals is underestimated by as much as 4 dB. The use of coherent integration in reducing the effect of aliased power line harmonics is pointed out.

Rastogi, P. K.

1983-01-01

168

Testbed for development of a DSP-based signal processing subsystem for an earth-orbiting radar scatterometer  

Microsoft Academic Search

A testbed for evaluation of general-purpose digital signal processors in earth-orbiting radar scatterometers is discussed. Because general purpose DSP represents a departure from previous radar signal processing techniques used on scatterometers, there was a need to demonstrate key elements of the system to verify feasibility for potential future scatterometer instruments. Construction of the testbed also facilitated identification of an appropriate

Douglas J. Clark; James P. Lux; N. Shirbacheh

2002-01-01

169

Radar principles  

NASA Astrophysics Data System (ADS)

The basic operating principles, design, and applications of radars are discussed in an introductory text intended for first-year graduate students. Topics addressed include radar measurements, radar target cross sections, radar detection, ground effects, matched filters, ambiguity functions, coded radar signals, and radar measurement accuracy. Consideration is given to processing coherent pulse trains, moving-target indicators, CFAR, SAR, and monopulse antenna tracking. Extensive diagrams and graphs are provided.

Levanon, Nadav

170

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

171

Signal Processing Methods for Millimetrewave FMCW Radar with High Distance and Doppler Resolution  

Microsoft Academic Search

Novel FMCW radar concepts for precise distance and velocity measurement are presented. The systems incorporate a SAW reference delay line used to measure the instantaneous phase of the oscillator signal. The algorithms evaluate the specific effects of Doppler frequency shifts in the presence of phase errors such as oscillator phase noise or a nonlinear FM modulation. A method that combines

M. Vossiek; T. v. Kerssenbrock; P. Heide

1997-01-01

172

Multi-target signal processing in FMCW radar system with antenna array  

Microsoft Academic Search

In the frequency modulated continuous wave radar systems, when the transmitter uses periodic linear symmetric triangular wave modulation, the received signal after processed by the mixer will have many harmonics. In the single target detection, this effect can be ignored. However, in the multi-target detection, targets with different ranges and velocities lead to overlapping of the harmonics. Using the peak

Kai-Wen Cheng; Hsuan-Jung Su

2008-01-01

173

Signal processing techniques for damage detection with piezoelectric wafer active sensors and embedded ultrasonic structural radar  

Microsoft Academic Search

Embedded ultrasonic structural radar (EUSR) algorithm is developed for using piezoelectric wafer active sensor (PWAS) array to detect defects within a large area of a thin-plate specimen. Signal processing techniques are used to extract the time of flight of the wave packages, and thereby to determine the location of the defects with the EUSR algorithm. In our research, the transient

Lingyu Yu; Jingjing Bao; Victor Giurgiutiu

2004-01-01

174

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

175

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

176

UWB radar signal processing for through wall tracking of multiple moving targets  

Microsoft Academic Search

Through wall tracking can be very helpful in the situations where the entering of a room or a building is considered hazardous and it is desired to inspect its interior from outside through the walls. In majority of such cases, the tracking of multiple moving targets is needed. The radar signal processing for this application has to deal with several

D. Kocur

2010-01-01

177

A novel deinterleaving algorithm of radar pulse signal based on DSP  

Microsoft Academic Search

A deinterleaving algorithm of radar signal based on DSP is presented in this paper, which is according to the structure of the deinterleaving system, characteristics of PDW (pulse descriptor word) and histogram method. The threshold determination, accumulation of PRI (pulse repetition interval) and others in the algorithm applied in different fields are introduced in detail. The experimental results and comparison

Wang Jun; Lei Peng; Yang Dong; Li Wei; Yan Xinyu

2009-01-01

178

Real-Time Digital Signal Processing of Component-Oriented Phased Array Radars  

Microsoft Academic Search

With the advance of hardware and software technology, modern phased array radars are now built with commercial off-the-shelf (COTS) components, and it opens up a new era in real-time resource scheduling of digital signal processing. This paper targets the essential issues in building a component-oriented signal processor (SP), which is one of the two major modules in modern phased array

Chin-fu Kuo; Tei-wei Kuo; Cheng Changt

2000-01-01

179

Signal model and linearization for nonlinear chirps in FMCW Radar SAW-ID tag request  

Microsoft Academic Search

In this paper, we present a frequency-modulated continuous-wave radar interrogation concept, based on direct digital synthesis (DDS), that operates without the commonly necessary high-frequency DDS reference oscillator. As the generated frequency sweeps are nonlinear, standard Fourier transform methods for baseband signal evaluation cannot be applied directly. We show the corresponding signal model, derive a linearization concept on the basis of

Stefan Scheiblhofer; Stefan Schuster; Andreas Stelzer

2006-01-01

180

An Adaptive Radar Target Signal Processing Scheme Based on AMTI Filter and Chaotic Neural Networks  

Microsoft Academic Search

In the proposed new scheme of adaptive radar target signal processing, the chaotic neural network not only detects the target\\u000a signal by reconstructing the chaotic clutter, but also repairs the frequency spectrum according to its associative memory\\u000a characteristic. The clutter is filtered by the Burg algorithm based on the adaptive MTI filter. The information of distance\\u000a and velocity is also

Quansheng Ren; Jian Wang; Hongling Meng; Jianye Zhao

2007-01-01

181

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 10 GHz and 40 GHz, 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

182

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

NASA Astrophysics Data System (ADS)

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

Govoni, Mark A.; Li, Hongbin

2010-04-01

183

A novel radar sensor for the non-contact detection of speech signals.  

PubMed

Different speech detection sensors have been developed over the years but they are limited by the loss of high frequency speech energy, and have restricted non-contact detection due to the lack of penetrability. This paper proposes a novel millimeter microwave radar sensor to detect speech signals. The utilization of a high operating frequency and a superheterodyne receiver contributes to the high sensitivity of the radar sensor for small sound vibrations. In addition, the penetrability of microwaves allows the novel sensor to detect speech signals through nonmetal barriers. Results show that the novel sensor can detect high frequency speech energies and that the speech quality is comparable to traditional microphone speech. Moreover, the novel sensor can detect speech signals through a nonmetal material of a certain thickness between the sensor and the subject. Thus, the novel speech sensor expands traditional speech detection techniques and provides an exciting alternative for broader application prospects. PMID:22399895

Jiao, Mingke; Lu, Guohua; Jing, Xijing; Li, Sheng; Li, Yanfeng; Wang, Jianqi

2010-01-01

184

Synthetic aperture radar signal data compression using block adaptive quantization  

NASA Technical Reports Server (NTRS)

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

Kuduvalli, Gopinath; Dutkiewicz, Melanie; Cumming, Ian

1994-01-01

185

Feature of manifestation of light scattering phase effects and their influence on the Doppler signal of laser radar  

Microsoft Academic Search

Studies of various multicomponent laser Doppler radar (MLDR) demonstrated that polarization phase effects of scattering can in some cases considerably affect the signal-to- noise (s\\/n) ratio of the Doppler signal. A study of the Doppler signal is possible on the basis of the vector scattering theory and optical coherence theory. Simple expressions of the Doppler signal at the photodetector output,

Vladimir M. Zemlianskii; Felix J. Yanovsky

1995-01-01

186

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

NASA Technical Reports Server (NTRS)

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

Frehlich, Rod

1993-01-01

187

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

188

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

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

189

Wideband ambiguity matrix of LFM-signals used in polarimetric radar allowing simultaneous measurement of scattering matrix elements  

Microsoft Academic Search

A pair of concurrent up- and down-going Linear Frequency Modulated (LFM) wideband signals is used in a polarimetric radar allowing simultaneous measurement of all scattering matrix elements. In wideband LFM radar the ambiguity function for a selected polarization at transmit and receive and presented in the delay time versus Doppler frequency coordinate system shows a skewness. This skewness affects the

G. P. Babur; L. P. Ligthart

2008-01-01

190

Architecture and implementation for high-bandwidth real-time radar signal transmission and computing application  

NASA Astrophysics Data System (ADS)

he design, architecture, and implementation for the high-throughput data transmission and high-performance computing,which are applicable for various real-time radar signal transmission applications over the data network, are presented. With a client-server model, the multiple processes and threads on the end systems operate simultaneously and collaborately to meet the real-time requirement. The design covers the Digitized Radar Signal (DRS) data acquisition and data transmission on the DRS server end as well as DRS data receiving, radar signal parameter computation and parameter transmission on the DRS receiver end. Generic packet and data structures for transmission and inter-process data sharing are constructed. The architecture was successfully implemented on Sun/Solaris workstations with dual 750 MHz UltraSPARC-III processors containing Gigabit Ethernet card. The comparison in transmission throughput over gigabit link between with computation and without computation clearly shows the importance of the signal processing capability on the end-to-end performance. Profiling analysis on the DRS receiver process shows the work-loaded functions and provides guides for improving computing capabilities.

Cho, Yoong-Goog; Chandrasekar, V.; Jayasumana, Anura P.; Brunkow, David

2002-06-01

191

Study of the ballistocardiogram signal in life detection system based on radar.  

PubMed

In this article, our study of non-contact method via radar for monitoring the heart and respiratory rates of human subject is reported. The system is constructed which synchronously detects the electrocardiogram signals by the electrocardiograph and the ballistocardiogram signals by the non-contact life parameter detecting technology. Also, the detected signals are analyzed respectively in the time and frequency domain. The results show that the cycle of the ballistocardiogram is obvious in time domain and that the rhythm of the two kinds of signals keeps consistent. And their characteristic points in frequency domain are also the same. The clinical medicine usefulness of ballistocardiogram detected by the non-contact technology is approved and the credible evidence for the succeeding signal analysis and the clinical application is provided. Furthermore, the characters of the heartbeat signal detected by our system and the reasons for that are also discussed in detail in our paper. PMID:18002424

Guohua, Lu; Jianqi, Wang; Yu, Yue; Xijing, Jing

2007-01-01

192

Application of optoelectronic devices to radar signal transmission and processing  

NASA Astrophysics Data System (ADS)

It is pointed out that the increase in the operating frequency of optoelectronic devices as well as the very large bandwidth of single-mode optical fibers permits their advantageous utilization in electronic systems for the transmission and processing of microwave signals. The use of narrow-linewidth optical sources as the DFB laser diode should make it possible to reach high B2L figure of merits. These laser diodes will be directly modulated through current injection up to 30 GHz, while the use of integrated-optics external modulators should make it possible to go beyond this value. Attention is given to such examples as point-to-point links from a few meters to several dozen kiloometers, as well as to signal processing subsystems, delay lines, and filters.

de Cremoux, Baudouin

193

A digital signal processing system for coherent laser radar  

NASA Technical Reports Server (NTRS)

A data processing system for use with continuous-wave lidar is described in terms of its configuration and performance during the second survey mission of NASA'a Global Backscatter Experiment. The system is designed to estimate a complete lidar spectrum in real time, record the data from two lidars, and monitor variables related to the lidar operating environment. The PC-based system includes a transient capture board, a digital-signal processing (DSP) board, and a low-speed data-acquisition board. Both unprocessed and processed lidar spectrum data are monitored in real time, and the results are compared to those of a previous non-DSP-based system. Because the DSP-based system is digital it is slower than the surface-acoustic-wave signal processor and collects 2500 spectra/s. However, the DSP-based system provides complete data sets at two wavelengths from the continuous-wave lidars.

Hampton, Diana M.; Jones, William D.; Rothermel, Jeffry

1991-01-01

194

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.

195

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

196

A High Precision 24 GHz FMCW-Radar using a Phase-Slope Signal Processing Algorithm  

Microsoft Academic Search

A 24 GHz FMCW-radar system is presented using a phase-slope algorithm for increased range determination accuracy. Additionally a fractional-N ramp generator provides a highly linear frequency ramp with nonlinearities below 10¿8. These highly linear frequency ramps make post measurement error correction feasible. Especially analysing the phase-slope of the i.f. signal results in an increased measurement precision compared to the standard

T. Musch

2002-01-01

197

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

Microsoft Academic Search

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

WILLIAM L. MELVIN; JOSEPH R. GUERCI

2006-01-01

198

Robust separation of background and target signals in radar cross section measurements  

Microsoft Academic Search

Coherent measurements of radar cross-section on a target moving along the system line-of-sight in free space will trace a circle centered on the origin of the complex (I,Q) plane. The presence of additional complex background signals (including stationary clutter, target support, and averaged target-mount interactions), which do not depend on target position, will translate the origin of the circle to

Lorant A. Muth; Chih-Ming Wang; Timothy Conn

2005-01-01

199

Real-time MST radar signal processing using a microcomputer running under FORTH  

Microsoft Academic Search

Data on power, correlation time, and velocity were obtained at the Urbana radar using microcomputer and a single floppy disk drive. This system includes the following features: (1) measurement of the real and imaginary components of the received signal at 20 altitudes spaced by 1.5 km; (2) coherent integration of these components over a 1\\/8-s time period; (3) continuous real

S. A. Bowhill

1983-01-01

200

Signal processing techniques for forward imaging using ultrawideband synthetic aperture radar  

NASA Astrophysics Data System (ADS)

The U.S. Army Research Laboratory (ARL), as part of a customer and mission-funded exploratory development program, has been developing a prototype of low-frequency, ultra-wideband (UWB) forward-imaging synthetic aperture radar (SAR) to support the U.S. Army's vision for increased mobility and survivability of unmanned ground vehicle missions. The ability of the UWB radar technology to detect objects under foilage could provide an important obstacle-avoidance capability for robotic vehicles, which could improve the speed and maneuverability of these vehicles and consequently increase the survivability of the U.S. forces. In a recent experiment at Aberdeen Proving Ground (APG), we exercised the UWB SAR radar in forward-looking mode and collected data to support the investigation. This paper discusses the signal processing algorithms and techniques that we developed and applied to the recent UWB SAR forward-looking data. The algorithms include motion data processing, self-interference signal (SIR) removal, radio frequency interference (RFI) signal removal, forward-looking image formation, and visualization techniques. We present forward-loking SAR imagery and also volumetric imagery of some targets.

Nguyen, Lam H.; Ton, Tuan T.; Wong, David C.; Ressler, Marc A.

2003-09-01

201

2-D FFT and time-frequency analysis techniques for multi-target recognition of FMCW radar signal  

Microsoft Academic Search

A study of multi-object recognition method of a linear frequency-modulated continuous-wave (FMCW) radar system is presented. Principles of FMCW signal with its relation to the characteristics of the detected objects are reviewed. Two-dimensional fast Fourier transform (FFT) and time-frequency analysis (TFA) techniques are performed calculating information of detected objects from received radar signals. In time-frequency analysis, techniques including Gabor transform

Li Su; Hsien Shun Wu; Ching-Kuang C. Tzuang

2011-01-01

202

New 100 MHz bandwidth vector signal analysis measurement technique for R&D in radar development, EW and surveillance  

Microsoft Academic Search

Many new and next generation wide bandwidth microwave radar, EW and surveillance applications require measurement and analysis of RF and microwave signals with wide bandwidth analog and digital modulation. This paper describes a new measurement technique featuring 100 MHz of information bandwidth signal analysis capability, including spectrum analysis and modulation analysis of RF and microwave signals with wide bandwidth complex

L. Dickstein; B. Matreci

1998-01-01

203

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

204

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

205

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

206

Phase coherence and Signal-To-Noise ratio considerations for sampled aperture radar systems  

NASA Astrophysics Data System (ADS)

This report describes the application of Sampled Aperture Radar (SAMPAR) technology to the tracking of low-angle targets of low-angle targets at sea. In particular, expressions are developed and presented describing aperture signals for a conventional (SAMPAR) configuration which uses coherent local oscillators. The radar signals are shown to contain an interference term in which is contained all of the information used during Correlation Height Analysis (CHA) processing. A continuous wave (CW) experiment designed to evaluate the CHA algorithm is described. This system employs a beacon source and self-cohering receivers. It is shown that the same interference term is also contained in the self-cohered received signal. Some pre-processing of the interference term is required prior to CHA processing to optimize the results. A discussion is given of the implementation of Doppler processing for various target velocities. Finally a discussion is given of signal-to-noise ratios for typical target geometries and sea-state conditions, in which forward-scatter clutter, back-scatter clutter and system noise are taken into account.

Litva, J.; Chan, H. C.

1987-12-01

207

Possibilities of using fast Fourier transform processors in radar signal filtering and interpretation  

Microsoft Academic Search

The principle of FFT filtering is studied, and a review of current applications of FFT processors in radar technology is given. This includes FFT in CW-FM radar, in Doppler filtration for surveillance radar, and in pulse Doppler radar. Limitations on the use of FFT processors are discussed along with prospects for further extension of FFT methods in radar.

H. Ebert

1974-01-01

208

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

209

An airborne recording system for Secondary Surveillance Radar (SSR) uplink signals  

NASA Astrophysics Data System (ADS)

A system for recording and displaying the signals reaching an aircraft from a secondary surveillance radar interrogator was developed. It can be used to study the characteristics of interrogators and their aerials, and also the effect of multipath interference on the uplink. A charge coupled device Fairchild CCD 321A-2 is used to compress the bandwidth of the signals so that an instrumentation tape recorder can record them. Digital circuitry generates fast and slow sampling clocks and applies them alternately to the CCD to achieve bandwidth compression. On being replayed, the signals are converted to digital form to enable a computer to display various features, e.g., video waveforms and polar diagrams.

Fairhead, A. C.

1980-06-01

210

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

NASA Technical Reports Server (NTRS)

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

Pujol, A.

1982-01-01

211

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

212

Prediction of attenuation of the 28 GHz COMSTAR beacon signal using radar and measured rain drop spectra  

NASA Technical Reports Server (NTRS)

Disdrometer measurements and radar reflectivity measurements were injected into a computer program to estimate the path attenuation of the signal. Predicted attenuations when compared with the directly measured ones showed generally good correlation on a case by case basis and very good agreement statistically. The utility of using radar in conjunction with disdrometer measurements for predicting fade events and long term fade distributions associated with earth-satellite telecommunications is demonstrated.

Goldhirsh, J.

1977-01-01

213

Comparison of linear and logarithmic receiver signals from polarimetric weather radar echoes and their temporal decorrelation properties  

Microsoft Academic Search

Usually common polarimetric weather radar DSP-products (e.g.: reflectivity, differential reflectivity, linear depolarisation ratio - for both - co-polar and cross-polar signal components) are based on the logarithmic receiver output, because of the large dynamic range provided by the logarithmic receiver. In this paper for the first time we also use the linear receiver output to calculate common weather radar DSP-Products.

P. Tracksdorf; A. Ghorbani; M. Chandra; M. Hagen; D. Bebbington

2005-01-01

214

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

215

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

216

A Novel Method of Distance Measurement Based on Pulse Position Modulation and Synchronization of Chaotic Signals Using Ultrasonic Radar Systems  

Microsoft Academic Search

This paper deals with a novel method of transmission and receipt of a signal based on both the property of two chaotic systems generating the same chaotic signal when they are synchronized and the property of pulse position modulation (PPM) to be insensitive to the distortions of the transmission channel. The method is discussed in the context of ultrasonic radar

Francesco Alonge; Marco Branciforte; Francesco Motta

2009-01-01

217

Detailed analysis of the factors affecting emitter recombination in solar cells through the small-signal voltage decay method  

Microsoft Academic Search

A general solution to the coupled time-dependent diffusion equations that describe minority carrier decay in any open-circuit solar cell is presented. Emitter bandgap narrowing is taken into account. The effective lifetime derived from voltage decay measurements can be accurately related to recombination rates in the emitter and in the base. In order to obtain closed-form solutions, it is assumed that

Kuntal Joardar; Dieter K. Schroder; C. E. Backus

1990-01-01

218

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

219

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

220

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

221

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

NASA Astrophysics Data System (ADS)

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

Wildey, Robert L.

1988-06-01

222

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

NASA Technical Reports Server (NTRS)

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

Wildey, Robert L.

1988-01-01

223

Active radar stealth device  

NASA Astrophysics Data System (ADS)

This patent discloses an active radar stealth device mounted on a host platform for minimizing the radar cross-section of the host platform. A coating which is essentially microwave transparent is attached to the surface of a host platform and is exposed to an incident microwave field. A plurality of detector/emitter pairs contained within the coating detect and actively cancel, respectively, the microwave field at each respective detector/emitter pair.

Cain, R. N.; Corda, Albert J.

1991-07-01

224

Ground-penetrating radar signal processing techniques for road subsurface measurements  

NASA Astrophysics Data System (ADS)

This paper will describe novel techniques and results of the current project to employ advanced signal processing techniques to detect and classify subsurface layers. In particular, a computational fast layer tracking processing technique will be described along with results of the algorithm. It is expected that the ground penetrating radar and the results of current research will assist the Florida Department of Transportation in determining more accurate road layer thickness profiles, assessing road subsurface conditions with less coring, and rehabilitating roads with less manpower than is now required. Such capabilities will allow potentially serious problems to be corrected before they become costly and will also provide a useful tool for future road design and improvement.

Cowdery, Jason M.; Kurtz, James L.

1999-07-01

225

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

226

Analysis of Low Probability of Intercept (LPI) Radar Signals Using Cyclostationary Processing.  

National Technical Information Service (NTIS)

LPI radar is a class of radar systems that possess certain performance characteristics that make them nearly undetectable by today's digital intercept receivers, This presents a significant tactical problem in the battle space To detect these types of rad...

A. F. Lime

2002-01-01

227

Multi-damage detection with embedded ultrasonic structural radar algorithm using piezoelectric wafer active sensors through advanced signal processing  

Microsoft Academic Search

The embedded ultrasonic structural radar (EUSR) algorithm was developed by using piezoelectric wafer active sensor (PWAS) array to detect defects within a large area of a thin-plate specimen. EUSR has been verified to be effective for detecting a single crack either at a broadside or at an offside position. In this research, advanced signal processing techniques were included to enhance

Lingyu Yu; Victor Giurgiutiu

2005-01-01

228

Innovative tools for radar signal processing Based on Cartan’s geometry of SPD matrices & Information Geometry  

Microsoft Academic Search

New operational requirements for stealth targets detection in dense & inhomogeneous clutter are emerging (littoral warfare, low altitude asymmetric threats, battlefield in urban area...). Classical radar approaches for Doppler & array signal processing have reached their limits. We propose new improvements based on advanced mathematical studies on geometry of SPD matrix (symmetric positive definite matrix) and information geometry, using that

F. Barbaresco

2008-01-01

229

Active radar stealth device  

Microsoft Academic Search

This patent discloses an active radar stealth device mounted on a host platform for minimizing the radar cross-section of the host platform. A coating which is essentially microwave transparent is attached to the surface of a host platform and is exposed to an incident microwave field. A plurality of detector\\/emitter pairs contained within the coating detect and actively cancel, respectively,

R. N. Cain; Albert J. Corda

1991-01-01

230

Signal analysis and modeling of wind turbine clutter in weather radars  

Microsoft Academic Search

Lately, the continuing expansion of wind energy industry has led to the installation of several wind farms which are often in the vicinity of the weather radars. This is a source of growing concern for the weather radar community since wind turbines interfere with the normal operation of the weather radars. The wind turbine tower can drive the receivers into

Kumar Vijay Mishra; V. Chandrasekar

2010-01-01

231

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

232

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

233

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

NASA Technical Reports Server (NTRS)

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

Lee, Jonggil

1990-01-01

234

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.

235

Multi-damage detection with embedded ultrasonic structural radar algorithm using piezoelectric wafer active sensors through advanced signal processing  

NASA Astrophysics Data System (ADS)

The embedded ultrasonic structural radar (EUSR) algorithm was developed by using piezoelectric wafer active sensor (PWAS) array to detect defects within a large area of a thin-plate specimen. EUSR has been verified to be effective for detecting a single crack either at a broadside or at an offside position. In this research, advanced signal processing techniques were included to enhance inspection image quality and detect multiple damage. The signal processing methods include discrete wavelet transform for signal denoising, short-time Fourier transform and continuous wavelet transform for time-frequency analysis, continuous wavelet transform for frequency filtering, and Hilbert transform for envelope extraction. All these signal processing modules were implemented by developing a graphical user-friendly interface program in LabVIEW. The paper starts with an introduction of embedded ultrasonic structural radar algorithm, followed with the theoretical aspect of the phased array signal processing method. Then, the mathematical algorithms for advanced signal processing are introduced. In the end, laboratory experimental results are presented to show how efficiently the improved EUSR works. The results are analyzed and EUSR is concluded to have been improved by using the advanced signal processing techniques. The improvements include: 1) EUSR is able to provide better image of the specimen under monitoring; 2) it is able to detect multi-damage such as several cracks; 3) it is able to identify different damage types.

Yu, Lingyu; Giurgiutiu, Victor

2005-05-01

236

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

National Technical Information Service (NTIS)

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...

D. A. Frickey

1995-01-01

237

Parametric Velocity Synthetic Aperture Radar:Signal Modeling and Optimal Methods  

Microsoft Academic Search

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

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

2008-01-01

238

Absorption of MARSIS radar signals: Solar energetic particles and the daytime ionosphere  

Microsoft Academic Search

We present observations from the subsurface sounding mode of the MARSIS instrument onboard Mars Express that imply radar wave absorption because of increased amounts of ionization in the upper Martian atmosphere during the fall of 2005. On at least two occasions these radar disruptions lasted for several days and we find that these periods are correlated with periods when other

Jared R. Espley; William M. Farrell; David A. Brain; David D. Morgan; Bruce Cantor; Jeffrey J. Plaut; Mario H. Acuña; Giovanni Picardi

2007-01-01

239

Classification of ground moving targets in the exoclutter region of airborne radar signals  

Microsoft Academic Search

An airborne radar sensor operating in ground moving target indicator (GMTI) mode is able to distinguish between airborne targets and ground moving targets. Further it is possible to separate stationary from moving ground targets. For military radar applications, it is desirable that the GMTI mode be extended to allow classification of detected ground targets. In addition, such an extension should

D. Nagel; C. Neumann; S. Smith

2008-01-01

240

Radar cross section  

Microsoft Academic Search

The technological evolution in signal processing that has been made in last decades led to improvements in radar performances. Increasing the radar range by improving its sensitivity has been made by the designers of aircraft and other military systems to try to decrease the radar cross section of these types of equipment. The radar cross section is a matter of

L. Nicolaescu; Teofil Oroian

2001-01-01

241

A mixed-signal X-band SiGe multi-function control MMIC for phased array radar applications  

Microsoft Academic Search

In this paper is reported the design, fabrication and test of a mixed-signal SiGe X-band multi-function control MMIC for phased array radar applications. Said MMIC, fabricated, with the ST-Microelectronics BiCMOS7RF SiGe technology, comprises a 5-bit phase shifter, 5-bit attenuator, SPDT switches, several gain amplifiers and a digital serial to parallel converter to reduce the number of MMIC I\\/O control lines.

D. Carosi; A. Bettidi; A. Nanni; L. Marescialli; A. Cetronio

2009-01-01

242

Frequency diversity wideband digital receiver and signal processor for solid-state dual-polarimetric weather radars  

NASA Astrophysics Data System (ADS)

The recent spate in the use of solid-state transmitters for weather radar systems has unexceptionably revolutionized the research in meteorology. The solid-state transmitters allow transmission of low peak powers without losing the radar range resolution by allowing the use of pulse compression waveforms. In this research, a novel frequency-diversity wideband waveform is proposed and realized to extenuate the low sensitivity of solid-state radars and mitigate the blind range problem tied with the longer pulse compression waveforms. The latest developments in the computing landscape have permitted the design of wideband digital receivers which can process this novel waveform on Field Programmable Gate Array (FPGA) chips. In terms of signal processing, wideband systems are generally characterized by the fact that the bandwidth of the signal of interest is comparable to the sampled bandwidth; that is, a band of frequencies must be selected and filtered out from a comparable spectral window in which the signal might occur. The development of such a wideband digital receiver opens a window for exciting research opportunities for improved estimation of precipitation measurements for higher frequency systems such as X, Ku and Ka bands, satellite-borne radars and other solid-state ground-based radars. This research describes various unique challenges associated with the design of a multi-channel wideband receiver. The receiver consists of twelve channels which simultaneously downconvert and filter the digitized intermediate-frequency (IF) signal for radar data processing. The product processing for the multi-channel digital receiver mandates a software and network architecture which provides for generating and archiving a single meteorological product profile culled from multi-pulse profiles at an increased data date. The multi-channel digital receiver also continuously samples the transmit pulse for calibration of radar receiver gain and transmit power. The multi-channel digital receiver has been successfully deployed as a key component in the recently developed National Aeronautical and Space Administration (NASA) Global Precipitation Measurement (GPM) Dual-Frequency Dual-Polarization Doppler Radar (D3R). The D3R is the principal ground validation instrument for the precipitation measurements of the Dual Precipitation Radar (DPR) onboard the GPM Core Observatory satellite scheduled for launch in 2014. The D3R system employs two broadly separated frequencies at Ku- and Ka-bands that together make measurements for precipitation types which need higher sensitivity such as light rain, drizzle and snow. This research describes unique design space to configure the digital receiver for D3R at several processing levels. At length, this research presents analysis and results obtained by employing the multi-carrier waveforms for D3R during the 2012 GPM Cold-Season Precipitation Experiment (GCPEx) campaign in Canada.

Mishra, Kumar Vijay

243

Analysis of complex radar data sets using fuzzy adaptive resonance theory map  

NASA Astrophysics Data System (ADS)

This paper will evaluate one promising method used to solve one of the main problems in electronic warfare. This problem is the identification of radar signals in a tactical environment. The identification process requires two steps: clustering of collected radar pulse descriptor words and the classification of clustered results. The method described here, Fuzzy Adaptive Resonance Theory Map (Fuzzy ARTMAP) is a self-organizing neural network algorithm. The benefits of this algorithm are that the training process is very stable and fast and that it needs a small number of required initial parameters and it performs very well at novelty detection, which is the classification of unknown radar emitters. This paper will discuss the theory behind the Fuzzy ARTMAP, as well as results of the processing of two `i real^i radar pulse data sets. The first evaluated data set consists of 5242 radar pulse descriptor words from 32 different emitters. The second data set consists of 107850 pulse descriptor words from 112 different emitters. The radar pulse descriptors words that were used by the algorithm for both sets of data were radio frequency (RF) and pulse width (PW). The results of the processing of both of these datasets were better than 90% correct correlation with actual ID, which exceeds the results of processing these datasets with other algorithms such as K-Means and other self-organizing neural networks.

Thompson, Michael J.; Sciortino, John C., Jr.

2004-08-01

244

Time reversal, back propagation, matched field processors, correlation receivers, and the principles of radar/sonar signal design  

NASA Astrophysics Data System (ADS)

Time reversal and backpropagation have been demonstrated in several experiments. Similarly, while matched field processing (MFP) differs in terms of implentation-experimental vs computed replicas-both have two common properties: (i) they are based on a single, spatially coherent signal; and (ii) the conjugate transpose of the Green's function and replica correlation are identical for self-adjoint systems. Hence, the principles for focusing and ambiguity plane properties of these processors are virtually identical to those for correlation receivers. The principles of optimal signal design for correlation receivers were the subject of much research for radar/sonar systems four decades ago and many of them seem to have been neglected in the analysis of time reversal, back propagation, and matched field processors. For example, time reversal from a point, a line array, or a random array of scatterers are duals of an impulse, a frequency modulated, and a pseudo-random noise signal, respectively. The equivalence and consequences of the time-bandwidth products for signals and array length wave number spread are demonstrated. The impact of sidelobes and multipath spread can be predicted. The generalizations of the important radar/sonar uncertainty principle, however, have yet been not demonstrated. This presentation reviews these optimal signal design principles and applies them to time reversal and MFP.

Baggeroer, Arthur

2002-05-01

245

The use of radar backscattering signals for measuring soil moisture and surface roughness  

Microsoft Academic Search

In this article, the possible use of synthetic-aperture radar (SAR), for measuring the moisture content and surface roughness is analyzed. Data have been acquired on the Melarchez subwatershed during the Orgeval '89 campaign from March to December 1989. Radar back-scattering measurements were provided by the French airborne scatterometer ERASME. Simultaneous ground measurements of soil moisture and roughness, leaf-area index, and

M Benallegue; O Taconet; D Vidal-Madjar; M Normand

1995-01-01

246

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

247

Inferring microstructure and turbulence properties in rain through observations and simulations of signal spectra measured with Doppler–polarimetric radars  

Microsoft Academic Search

Doppler radars are able to measure important parameters of the target velocity. In contrast, polarimetric radars are very sensitive to features of the target shape and orientation relative to the radar beam direction. This chapter describes a novel Doppler–polarimetric approach to radar remote sensing. The combination of the Doppler ability and polarization diversity in the radar technology enables more comprehensive

Felix Yanovsky

2011-01-01

248

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

249

Principal-component filtering of single-shot laser radar signals  

NASA Astrophysics Data System (ADS)

In single-shot laser radar speckle noise, drop-outs, outliers, and eventually, non-cooperative targets are to be considered in order to ensure high accuracy and reliability of measurement data. The most common approach for the stabilization of laser radar data is temporal averaging over several shots. This, however, is not in all cases the best method for the reconstruction of noisy imagery data. It is shown that principal-component filtering can yield a remarkable improvement of accuracy and robustness of range data.

Rothe, Hendrik; Ginter, Olaf; Kasper, Andre

1994-09-01

250

Capillary-Based Multi-Nanoelectrospray Emitters  

PubMed Central

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-?L/min.

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

2008-01-01

251

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

252

The MST radar technique  

NASA Technical Reports Server (NTRS)

The coherent radar technique is reviewed with special emphasis to mesosphere-stratosphere-troposphere (MST) radars operating in the VHF band. Some basic introduction to Doppler radar measurements and the radar equation is followed by an outline of the characteristics of atmospheric turbulence, viewed from the scattering and reflection processes of radar signals. Radar signal acquisition and preprocessing, namely coherent detection, digital sampling, pre-integration and coding, is briefly discussed. The data analysis is represented in terms of the correlation and spectrum analysis, yielding the essential parameters: power, signal-to-noise ratio, average and fluctuating velocity and persistency. The techniques to measure wind velocities, viz. the different modes of the Doppler method as well as the space antenna method are surveyed and the feasibilities of the MST radar interferometer technique are elucidated. A general view on the criteria to design phased array antennas is given. An outline of the hardware of a typical MST radar system is presented.

Roettger, J.

1984-01-01

253

Polarimetric Borehole Radar System for Fracture Measurement  

Microsoft Academic Search

Radar polarimetry is a technology that overcomes the limitation between the radar resolution and the penetration depth of borehole radar. We have developed a stepped-frequency polarimetric borehole radar system. This is a polarimetric borehole radar system which measures the full-radar polarimetry in a borehole by changing the antenna arrangements. By using a network analyzer and an optical analog signal link,

Motoyuki Sato; Takashi Miwa

2000-01-01

254

The use of digital modulation signals in radar system for detection of nonlinear scatterers  

Microsoft Academic Search

This paper deals with initial application of digital modulation techniques in the radar systems utilizing non-linear junction detection (NLJD) principle. Various types of devices, such as handheld detectors for searching of hidden listening devices, have previously been developed and are commercially available. However, these devices transmit single frequency harmonic waveform which in general limits efficiency of energy transmission to nonlinear

Vladimir Polacek; Radomir Pavlik

2011-01-01

255

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

Microsoft Academic Search

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

Weige Chen; Guotong Zhou; G. B. Giannakis

1995-01-01

256

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

257

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

258

Application of pattern recognition techniques to the processing of radar signals  

Microsoft Academic Search

This paper presents numerous pattern recognition techniques which can be applied to radar data. In particular, nearest neighbor and linear discriminant function algorithms are discussed, as well as the use of different sets of features to represent the data. In addition, some of the most common applications are also discussed, including meteorological analyses and military applications.

N. Ezquerra; L. Harkness

1982-01-01

259

The ARPA\\/NAVY Mountaintop Program: adaptive signal processing for airborne early warning radar  

Microsoft Academic Search

The Mountaintop Program is an ARPA\\/NAVY sponsored initiative started in 1990 to study advanced processing techniques and technologies required to support the mission requirements of next generation airborne early warning (AEW) platforms. Central to the effort is a surveillance radar measurements program executed from various mountaintop locations including field sites at the White Sands Missile Range (WMSR), New Mexico and

Gerard W. Titi; Daniel F. Marshall

1996-01-01

260

A Novel Application of Lifting Scheme for Multiresolution Correlation of Complex Radar Signals  

Microsoft Academic Search

The lifting scheme of discrete wavelet transform (DWT) is now quite well established as an efficient technique for image compression, and has been incorporated into the JPEG2000 standards. However, the potential of the lifting scheme has not been exploited in the context of correlation - based processing, such as encountered in radar applications. This paper presents a complete and consistent

Chinmoy Bhattacharya; P. R. Mahapatra

2006-01-01

261

Signal processing techniques for landmine detection using impulse ground penetrating radar  

Microsoft Academic Search

Landmines are affecting the lives and livelihoods of millions of people around the world. A number of detection techniques, developed for use with impulse ground penetrating radar, are described, with emphasis on a Kalman filter based approach. Comparison of results from real data show that the Kalman filter algorithm provides the best detection performance, although its computational burden is also

Abdelhak M. Zoubir; Ian James Chant; Christopher L. Brown; Braham Barkat; Canicious Abeynayake

2002-01-01

262

Analysis of an optimum hybrid radar waveform using frequency hopping and locally optimum signals  

Microsoft Academic Search

The analysis of a new hybrid waveform designed to optimize both range and velocity resolution is described. Two modulation techniques, frequency agility and direct sequence spreading, are chosen to improve range resolution through pulse compression techniques. The frequency order in a frequency agile radar is chosen so there is at most one coincidence in frequency between the transmitted and Doppler

JEROME A. LEMIEUX

1991-01-01

263

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

264

Nonintercepting emittance monitor  

SciTech Connect

A nonintercepting emittance monitor is a helpful device for measuring and improving particle beams in accelerators and storage rings as it allows continuous monitoring of the beam's distribution in phase space, and perhaps closed loop computer control of the distributions. Stripline position monitors are being investigated for use as nonintercepting emittance monitors for a beam focused by a FODO array in the first 100 meters of our linear accelerator. The technique described here uses the signal from the four stripline probes of a single position monitor to measure the quadrupole mode of the wall current in the beam pipe. This current is a function of the quadrupole moment of the beam, sigma/sup 2//sub x/ - sigma/sup 2//sub y/. In general, six independent measurements of the quadrupole moment are necessary to determine the beam emittance. This technique is dependent on the characteristically large variations of sigma/sup 2//sub x/ - sigma/sup 2//sub y/ in a FODO array. It will not work in a focusing system where the beam is round at each focusing element.

Miller, R.H.; Clendenin, J.E.; James, M.B.; Sheppard, J.C.

1983-08-01

265

Automatic Radar Waveform Recognition  

Microsoft Academic Search

In this paper, a system for automatically recognizing radar waveforms is introduced. This type of techniques are needed in various spectrum management, surveillance and cognitive radio or radar applications. The intercepted radar signal is classified to eight classes based on the pulse compression waveform: linear frequency modulation (LFM), discrete frequency codes (Costas codes), binary phase, and Frank, P1, P2, P3,

Jarmo Lundn; Visa Koivunen

2007-01-01

266

Controlling radar signature  

Microsoft Academic Search

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

1992-01-01

267

Nonlinear signal processing schemes for robust target detection and automatic clutter rejection in radar  

Microsoft Academic Search

The application of a technique called Split-Spectrum Processing, which was developed to achieve frequency diversity in one-dimensional (A-scan) ultrasonic application, to radar was examined. The major highlights and accomplishments of the project are: (1) adaptive techniques for determination of optional processing parameters; (2) robust techniques for target detection; (3) non-parametric target detection techniques; (4) rank determination for order statistic filters;

Nihat M. Bilgutay; Kevin D. Donohue; Jafar Saniie

1992-01-01

268

Complementary Code and Digital Filtering for Detection of Weak VHF Radar Signals from the Mesosphere  

Microsoft Academic Search

Measurements of the structure and the dynamics of the middle atmosphere with a fine height resolution have been carried out using the SOUSY-VHF-Radar (SOUSY = SOUnding SYstem), operated by the Max-Planck-Institute for Aeronomy in the Harz mountains in Germany. Since the echoes from the middle atmosphere are coherent within a time scale of the order of a second, the received

Gerhard Schmidt; Rudiger Ruster; Peter Czechowsky

1979-01-01

269

Improving knowledge-aided STAP performance using past CPI data [radar signal processing  

Microsoft Academic Search

A technique for incorporating past coherent processing interval (CPI) radar data into knowledge-aided space-time adaptive processing (KASTAP) is described. The technique forms Earth-based clutter reflectivity maps to provide improved knowledge of clutter statistics in nonhomogeneous terrain environments. The maps are utilized to calculate predicted clutter covariance matrices as a function of range. Using a data set provided under the DARPA

Douglas Page; Steven Scarborough; S. Crooks

2004-01-01

270

Simulations of radar signals on the basis of cloud model results - deep convection conditions  

NASA Astrophysics Data System (ADS)

Simulation of observed radar returns is one of the tools for validating a new cloud microphysics code by H. Morrison and W.W. Grabowski. The code includes a two-moment bulk warm rain scheme and two-moment ice microphysics scheme with prognostic rime mass fraction. Both the simulator and the cloud model share the following set of assumptions. Three general types of particles are taken into account: cloud droplets, drizzle drops and ice crystals; particles are characterised by modified gamma size distribution (in case of rain drops it becomes exponential); and particles are described in terms of mass and area to dimension relationships. Liquid particles are assumed to be spherical and ice crystals are treated as spheres, dense non-spherical particles, graupel or aggregates, depending on their size and rimed mass fraction. Simulator input consists of particle number concentrations, mixing ratios (for ice crystals separate mixing ratios for mass grown by riming and water vapour deposition are employed), temperature and relative humidity profiles. Pre-calculated look up tables containing particle scattering properties (radar reflectivity and attenuation) as functions of input parameters are used in order to speed up the code. The simulator is applied to deep convection conditions observed during the Tropical Warm Pool International Cloud Experiment, Darwin, Australia, January - February 2006. The simulation results are compared to data collected by the millimeter wavelength cloud radar (MMCR) situated in Darwin, Australia - one of the measurement sites of the Atmospheric Radiation Measurement program.

Kardas, A. E.; McFarlane, S. A.; Morrison, H.; Comstock, J. M.; Grabowski, W. W.; Malinowski, S. P.

2009-12-01

271

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

NASA Technical Reports Server (NTRS)

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

Poultney, S. K.

1971-01-01

272

Emittance theory for thin film selective emitter  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

273

On the problem of the doppler spectrum of a microwave radar signal backscattered by the sea surface (transition region and bragg component)  

Microsoft Academic Search

We consider the problem of backscattering of a microwave radar signal by a perturbed water surface in the transition region of incidence angles (10° 25°). A theoretical model of the Doppler spectrum for the Bragg component of the reflected field is constructed within the framework of a two-scale model of the surface. Allowance for the large-scale component of waves indicates

V. Yu. Karaev

1997-01-01

274

Combined bispectrum-filtering techniques for radar output signal reconstruction in ATR applications  

Microsoft Academic Search

In automatic target recognition applications, an important task is to obtain denoised signal of the object. In this paper, the reconstruction of 1D deterministic signals, for example, range profiles, corrupted by random signal shift and additive white Gaussian noise using 2D bispectrum is considered. Combined bispectrum-filtering techniques based on smoothing the noisy bispectrum estimates by 2D linear and nonlinear filters

Alexander V. Totsky; Igor V. Kurbatov; Vladimir V. Lukin; Karen O. Egiazarian; Jaakko T. Astola

2003-01-01

275

RADAR SIGNAL FEATURE EXTRACTION SYSTEM BASED ON A SAW DISPERSIVE DELAY LINES  

Microsoft Academic Search

Spectral analysis of signals using frequency-to-time transformers (transducers) and time-to-frequency digital FFT procedures is theoretically recognized in general and effectively used in practice. Such analysis referred to CW harmonic signals or pulsed signals with known and relatively long time of appearance (large pulse width) is widely used because of its theoretically unlimited resolution and due to many practical benefits. Today

Adam KAWALEC; Andrzej PIENI??NY; S. Kaliski

276

Multidimensional radar picture  

NASA Astrophysics Data System (ADS)

In marine navigation systems, the three-dimensional (3D) visualization is often and often used. Echosonders and sonars working in hydroacustic systems can present pictures in three dimensions. Currently, vector maps also offer 3D presentation. This presentation is used in aviation and underwater navigation. In the nearest future three-dimensional presentation may be obligatory presentation in displays of navigation systems. A part of these systems work with radar and communicates with it transmitting data in a digital form. 3D presentation of radar picture require a new technology to develop. In the first step it is necessary to compile digital form of radar signal. The modern navigation radar do not present data in three-dimensional form. Progress in technology of digital signal processing make it possible to create multidimensional radar pictures. For instance, the RSC (Radar Scan Converter) - digital radar picture recording and transforming tool can be used to create new picture online. Using RSC and techniques of modern computer graphics multidimensional radar pictures can be generated. The radar pictures mentioned should be readable for ECDIS. The paper presents a method for generating multidimensional radar picture from original signal coming from radar receiver.

Waz, Mariusz

2010-05-01

277

Signal processing algorithms in stepped frequency continues wave ground penetrating radar  

Microsoft Academic Search

Broad use of underground sensing led to development of a new signal processing algorithms which can extract much more information about soil and underground objects physical characteristics. These algorithms require information about how specific attenuation is dependent upon frequency, about phase velocity of radio waves in soil or about signals phase structure in cases when underground objects are present or

A. A. Zelensky; A. V. Sugak; V. G. Sugak

2010-01-01

278

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

279

Helicopter obstacle detection radar system  

Microsoft Academic Search

We have analyzed and experimentally tested the feasibility of thin wire detection using millimeter wave radar. The radar system includes a novel, fast scanning antenna and a transceiver\\/signal processor unit from BAE systems.

Lev S. Sadovnik; Vladimir A. Manasson; Robert M. Mino

2000-01-01

280

Emitter utilization in heterojunction bipolar transistors  

NASA Astrophysics Data System (ADS)

We compare measured collector current densities, cutoff frequencies ( ft), and transducer gains for thermally shunted heterojunction bipolar transistors with 2-16 ?m emitter dot diameters or 2-8 ?m emitter bar widths with models of the emitter utilization factors. Models that do not take emitter resistance into account predict that the d.c. utilization factors are below 0.7 for collector current densities greater than 6 × 10 4 A cm -2 and emitter diameters or widths greater than 8 ?m. However, because the current gains are compressed by the emitter resistances at those current densities, the measured utilization factors are close to 1, which agrees with models that include emitter resistance. A.c. utilization factors are evident in the transistor Y parameters. For example, Re|Y 21z.sfnc drops off at high frequencies more steeply in HBTs with large emitter diameters or widths than in small ones. However, measured data shows that the HBT a.c. current gains h21 or ft values are not influenced by the a.c. utilization factor. A.c. utilization effects on HBT performance parameters such as small signal and power gains, output power, and power added efficiency are also examined.

Quach, T.; Jenkins, T.; Barrette, J.; Bozada, C.; Cerny, C.; Desalvo, G.; Dettmer, R.; Ebel, J.; Gillespie, J.; Havasy, C.; Ito, C.; Nakano, K.; Pettiford, C.; Sewell, J.; Via, D.; Anholt, R.

1997-09-01

281

Modelisation DU Signal Radar EN Milieu Stratifie et Evaluation de Techniques de Mesure de L'humidite DU Sol  

NASA Astrophysics Data System (ADS)

La presente etude se penche sur des problemes relies a l'echantillonnage de l'humidite de sol et a l'estimation du signal radar sur sols nus. Le travail se divise en deux volets. Le volet 1 evalue trois techniques de mesure de l'humidite du sol (gravimetrie, reflectometrie temporelle et sonde dielectrique) et deux protocoles d'echantillonnage. Dans le volet 2, un modele de simulation du signal en milieu stratifie est developpe, et les estimes de signal obtenus sont compares aux estimes bases uniquement sur une valeur moyenne d'humidite du sol prise sur une profondeur fixe d'echantillonnage. Les differences entre les deux estimes dependent de la frequence et du choix judicieux de la profondeur d'echantillonnage; elles sont plus importantes aux faibles angles et en polarisation HV, puis VV. Le modele de simulation a aussi ete utilise pour etudier la profondeur de penetration du signal et en deduire la profondeur optimale d'echantillonnage en tenant compte des caracteristiques du signal. Une variation de 25 ^circ de l'angle d'incidence a peu d'effet sur la profondeur de penetration en bande Ku; l'ecart reste inferieur ou egal a 0,5 cm en bande C mais peut atteindre 1,3 cm en bande L. L'impact de la polarisation est nul en bande Ku mais croi t avec l'angle d'incidence en bande C et L. A 50^circ, il est, en moyenne de 1 cm en bande C et de 2 cm en bande L. En polarisation VV, la profondeur croi t avec une augmentation de l'angle alors que l'effet est inverse en polarisation HH. Deux methodes pour estimer la profondeur d'echantillonnage en conditions operationnelles sont presentees. Lorsqu'on inverse un modele pour estimer l'humidite du sol a partir du signal, ces methodes permettent aussi d'estimer l'epaisseur de sol representee par l'humidite ainsi estimee.

Boisvert, Johanne

282

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

DOEpatents

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

283

Signal processing method for switch antenna array of the FMCW radar  

Microsoft Academic Search

The switch antenna array (SAA) is a promising substitute for multi-channel antenna array (MAA) due to its low cost, small volume and high resolution. The current signal processing method is efficient only in the low velocity and low frequency case. A new 2-dimension method is proposed, which is suitable to bearing estimation of moving objects without any restriction on their

Li Yang; Liang Liwan; Pan Weifeng; Chen Yaqin; Feng Zhenghe

2001-01-01

284

Radar signal delay in the Dvali-Gabadadze-Porrati gravity in the vicinity of the Sun  

NASA Astrophysics Data System (ADS)

In this paper we examine the recently introduced Dvali-Gabadadze-Porrati (DGP) gravity model. We use a space-time metric in which the local gravitation source dominates the metric over the contributions from the cosmological flow. Anticipating ideal possible solar system effects, we derive expressions for the signal time delays in the vicinity of the Sun. and for various ranges of the angle ? of the signal approach, The time contribution due to DGP correction to the metric is found to be proportional to b 3/2/ c 2 r 0. For r 0 equal to 5 Mpc and ? in the range [- ?/3, ?/3], ? t is equal to 0.0001233 ps. This delay is extremely small to be measured by today's technology but it could be probably measurable by future experiments.

Haranas, Ioannis; Ragos, Omiros; Gkigkitzis, Ioannis

2012-11-01

285

Frequency-based target localization methods for widely separated MIMO radar  

NASA Astrophysics Data System (ADS)

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

Kalkan, Y.��lmaz; Baykal, Buyurman

2014-01-01

286

On the problem of the doppler spectrum of a microwave radar signal backscattered by the sea surface (transition region and bragg component)  

Microsoft Academic Search

We consider the problem of backscattering of a microwave radar signal by a perturbed water surface in the transition region\\u000a of incidence angles (10?–25?). A theoretical model of the Doppler spectrum for the Bragg component of the reflected field\\u000a is constructed within the framework of a two-scale model of the surface. Allowance for the large-scale component of waves\\u000a indicates that

V. Yu. Karaev

1997-01-01

287

Carbon nanotube field emitter.  

PubMed

Recently, carbon nanotubes (CNTs), possessing excellent properties as field emitters, are attracting considerable attention as electron emitters of a cold cathode. In this review article, field emission phenomena of carbon nanotubes with various morphologies and surfaces (clean surface or adsorbed molecules on it) revealed by field emission microscopy are first described. Then, the main subject of this article, application of CNTs as electron sources in display devices is reviewed. Other electric devices utilizing CNT-field emitters are also presented. PMID:12908229

Saito, Yahachi

2003-01-01

288

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

289

Locating RF emitters with large UAV teams  

Microsoft Academic Search

This chapter describes a principled, yet computationally ecient way for a team of UAVs with Received Signal Strength Indicator (RSSI) sen- sors to locate radio frequency emitting ground vehicles in a large envi- ronment. Such a capability has a range of both civilian and military applications. RSSI sensor readings are noisy and multiple emitters will cause ambiguous, overlapping signals to

Paul Scerri; Robin Glinton; Sean Owens; Steven Okamoto; Katia P. Sycara

2007-01-01

290

Target identification from radar signatures  

Microsoft Academic Search

Modern high resolution radar techniques and real time digital signal processing advances indicate the feasibility of extracting characteristic features of aircraft targets from their radar signatures. Two basic approaches have been suggested. The low frequency approach utilizes harmonically related radar frequencies with wavelengths comparable to the target dimensions. The microwave approach utilizes spread spectrum techniques to achieve high range resolution.

R. Strattan

1978-01-01

291

Harmonic radar literature  

NASA Astrophysics Data System (ADS)

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 radar has an extremely low range of detection. Natural objects in the target area do not disturb the high frequency harmonics. The radar becomes clutter free. The principals of generating high frequency harmonics cover tunneling, semiconductor and microwave effects. Signal generation is most powerful when f sub o is between 100 and 1000 MHz.

Jansson, B.

1980-07-01

292

Diamond fiber field emitters  

SciTech Connect

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

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

1996-01-01

293

The impact of phase noise parameters on target signal detection in FMCW-radar system simulations for automotive applications  

Microsoft Academic Search

Accurate system simulations have proven to be a valuable aid during the development process and help to decrease the time-to-market and the amount of design iterations, thus keeping development costs at a moderate level. Therefore a frequency-modulated continuous-wave (FMCW) radar system simulation environment has been built up, enabling for performance analysis of millimeter-wave radar frontends for automotive applications. A key

M. Dudek; I. Nasr; D. Kissinger; R. Weigel; G. Fischer

2011-01-01

294

Pulsed hybrid field emitter  

DOEpatents

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

Sampayan, Stephen E. (Manteca, CA)

1998-01-01

295

Pulsed hybrid field emitter  

DOEpatents

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

Sampayan, S.E.

1998-03-03

296

FMCW radar with broadband communication capability  

Microsoft Academic Search

The use of amplitude modulation to encode information onto an FMCW radar signal is proposed in this paper. This new technique, that has been named AM-FMCW communicating radar, provides a new channel for broadband communication by reusing the radar frequencies and without introducing any distortion in the radar functionality.

Peli Barrenechea; Frans Elferink; Johan Janssen

2007-01-01

297

Orthogonal waveforms for FMCW MIMO radar  

Microsoft Academic Search

Multiple input\\/multiple output (MIMO) radar system performance benefits from the capability to simultaneously transmit and receive multiple orthogonal waveforms. For pulse radars fitting orthogonal waveforms have been developed. These waveforms are however not necessarily suitable for frequency- modulated continuous-wave (FMCW) radar. The major benefit of the FMCW radar principle is that the bandwidth of the beat signal is generally much

J. J. M. de Wit; W. L. van Rossum; A. J. de Jong

2011-01-01

298

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

299

Ultra narrow band adaptive tomographic radar  

Microsoft Academic Search

This paper addresses the issue of spatial diversity in radar applications. Typically, information concerning ground and air targets is obtained via monostatic radar. Increased information is often equated with increased bandwidth in these radar systems. However, geometric diversity obtained through multistatic radar operations also affords the user the opportunity to obtain additional information concerning threat targets. With the appropriate signal

Michael C. Wicks; Braham Himed; J. L. E. Bracken; H. Bascom; J. Clancy

2005-01-01

300

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

PubMed

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

Lashkari, Bahman; Mandelis, Andreas

2011-09-01

301

A microprogrammable radar controller  

NASA Technical Reports Server (NTRS)

The Wave Propagation Lab. has completed the design and construction of a microprogrammable radar controller for atmospheric wind profiling. Unlike some radar controllers using state machines or hardwired logic for radar timing, this design is a high speed programmable sequencer with signal processing resources. A block diagram of the device is shown. The device is a single 8 1/2 inch by 10 1/2 inch printed circuit board and consists of three main subsections: (1) the host computer interface; (2) the microprogram sequencer; and (3) the signal processing circuitry. Each of these subsections are described in detail.

Law, D. C.

1986-01-01

302

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

303

Portable emittance measurement device.  

PubMed

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. PMID:20192459

Liakin, D; Seleznev, D; Orlov, A; Kuibeda, R; Kropachev, G; Kulevoy, T; Yakushin, P

2010-02-01

304

Emittance studies with an Allison scanner  

NASA Astrophysics Data System (ADS)

The Spallation Neutron Source H- source on the ion source test stand is being used to study the emittance of the H--ion beam injected into the SNS radiofrequency quadrupole (RFQ). The emittance measurements are performed with a LBNL Allison scanner that underwent several modifications. The slit width was optimized to improve the signal-to-noise ratio. In addition, the electric deflector plates were replaced with plates featuring a staircased surface. This modification is shown to suppress over 99% of ghost signals generated by the beam hitting the deflector plates. Both modifications, combined with noise suppression measures and a self-consistent analysis, yield highly accurate results. Measured emittances are presented as a function of the ion-beam current.

Stockli, M. P.; Welton, R. F.; Keller, R.; Leitner, M.

2006-03-01

305

Broadband Cascade Light Emitters.  

National Technical Information Service (NTIS)

A broadband Cascade Light Emitters (CLE) capable of operation simultaneously at multiple wavelengths comprises: a core region including a multiplicity or cascade of stages, each stage including a radiative transition region. A first group of stages emits ...

A. Soibel A. M. Sergent A. Y. Cho C. F. Gmachi D. L. Siven F. Capasso M. L. Peabody

2003-01-01

306

Laser Assisted Emittance Exchange  

SciTech Connect

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

Xiang, Dao; /SLAC

2012-06-11

307

Cancer from internal emitters.  

National Technical Information Service (NTIS)

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 emit...

B. B. Boecker W. C. Griffith

1995-01-01

308

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

309

High-resolution signal processing for a switch antenna array FMCW radar with a single channel receiver  

Microsoft Academic Search

Standard high resolution array processing techniques are based on simultaneous sampling of the whole multiple sensor array and, hence, require that the number of receivers should be equal to the number of receiving antennas. A switch antenna array FMCW radar system is introduced as a promising substitute for the multiple-channel array due to its lower cost and a simpler front-end

Vladimir Katkovnik; Moon-Sik Lee; Yong-Hoon Kim

2002-01-01

310

Shielded-emitter neutron detector  

Microsoft Academic Search

A self-powered neutron detector has a neutron-sensitive emitter, a collector enclosing this emitter and insulation between these two components. When irradiated by neutrons, the emitter generates Compton electrons so that a current is produced between the emitter and electrode and which may be used with a current-measuring device to provide a readout. The emitter is enclosed and electrically connected with

Klar

1976-01-01

311

Obstacle penetrating dynamic radar imaging system  

DOEpatents

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

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

2006-12-12

312

Emittance Degradation Measurements  

NASA Astrophysics Data System (ADS)

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

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

1997-05-01

313

Locating RF Emitters with Large UAV Teams  

Microsoft Academic Search

This chapter describes a principled, yet computationally efficient way for a team of UAVs with Received Signal Strength Indicator\\u000a (RSSI) sensors to locate radio frequency emitting ground vehicles in a large environment. Such a capability has a range of\\u000a both civilian and military applications. RSSI sensor readings are noisy and multiple emitters will cause ambiguous, overlapping\\u000a signals to be received

Paul Scerri; Robin Glinton; Sean Owens; Katia Sycara; Gerald Fudge; Joshua Anderson

314

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

315

Multitone harmonic radar  

NASA Astrophysics Data System (ADS)

Nonlinear radar exploits the electronic response from a target whose reflected frequencies are different from those transmitted. Reception of frequencies that are not part of the transmitted probe distinguishes the received signal from a linear return produced by clutter and indicates the presence of electronics. Presented in this paper is a type of nonlinear radar that transmits multiple frequencies and listens for a harmonic of these frequencies as well as other frequencies near that harmonic. A laboratory test-bed has been constructed to demonstrate the multitone radar concept. Measurements of nonlinear responses from RF devices probed by multiple tones are reported.

Mazzaro, Gregory J.; Martone, Anthony F.

2013-05-01

316

Non co-operative air target identification using radar imagery: identification rate as a function of signal bandwidth  

Microsoft Academic Search

Non-cooperative identification of (air) targets is still an unsolved problem though being of high relevance in the context of reliable friend-foe identification. In the past many methods have been proposed and investigated, e.g., by using the infrared, acoustical, optical or radar signatures of the targets. Some of these methods are passive ones, having the advantage of not alerting the observed

K. Rosenbach; J. Schiller

2000-01-01

317

Polarimetric radar modified  

NASA Astrophysics Data System (ADS)

Modification of 11-cm Doppler radar, to permit measurement of the complete polari-metric matrix of signals backscattered from meteorological media, was recently completed by the Ground Based Remote Sensing Branch of the Geophysics Laboratory, U.S. Air Force Base, Hanscom, Mass. It is believed that this radar is the only meteorological research radar in the world having such a capability at this wavelength. Signals can be transmitted with either linear or circular polarization and switched pulse-to-pulse either between horizontal and vertical or between right and left circular polarization.Backscattered signals with polarizations identical and orthogonal to that of the transmitted signal pass through coherent and logarithmic receivers and are recorded as time series in 40 selectable range gates. The resulting data archive supports a wide range of analyses, including auto- and cross-covariance calculations and spectral analyses.

318

Attenuation of Weather Radar Signals Due to Wetting of the Radome by Rainwater or Incomplete Filling of the Beam Volume  

NASA Technical Reports Server (NTRS)

A search of scientific literature, both printed and electronic, was undertaken to provide quantitative estimates of attenuation effects of rainfall on weather radar radomes. The emphasis was on C-band (5 cm) and S-Band (10 cm) wavelengths. An empirical model was developed to estimate two-way wet radome losses as a function of frequency and rainfall rate for both standard and hydrophobic radomes. The model fits most of the published data within +/- 1 dB at both target wavelengths for rain rates from less than ten to more than 200 mm/hr. Rainfall attenuation effects remain under 1 dB at both frequencies regardless of radome type for rainfall rates up to 10 mm/hr. S-Band losses with a hydrophobic radome such as that on the WSR-88D remain under 1 dB up to 100 mm/hr. C-Band losses on standard radomes such as that on the Patrick AFB (Air Force Base) WSR-74C can reach as much as 5 dB at 50 mm/hr. In addition, calculations were performed to determine the reduction in effective reflectivity, Z, when a radar target is smaller than the sampling volume of the radar. Results are presented for both the Patrick Air Force Base WSR-74C and the WSR-88D as a function of target size and range.

Merceret, Francis J.; Ward, Jennifer G.

2000-01-01

319

Analysis, comparison, and modeling of radar interferometry, date of surface deformation signals associated with underground explosions, mine collapses and earthquakes. Phase I: underground explosions, Nevada Test Site  

SciTech Connect

We have previously presented simple elastic deformation modeling results for three classes of seismic events of concern in monitoring the CTBT--underground explosions, mine collapses and earthquakes. Those results explored the theoretical detectability of each event type using synthetic aperture radar interferometry (InSAR) based on commercially available satellite data. In those studies we identified and compared the characteristics of synthetic interferograms that distinguish each event type, as well the ability of the interferograms to constrain source parameters. These idealized modeling results, together with preliminary analysis of InSAR data for the 1995 mb 5.2 Solvay mine collapse in southwestern Wyoming, suggested that InSAR data used in conjunction with regional seismic monitoring holds great potential for CTBT discrimination and seismic source analysis, as well as providing accurate ground truth parameters for regional calibration events. In this paper we further examine the detectability and ''discriminating'' power of InSAR by presenting results from InSAR data processing, analysis and modeling of the surface deformation signals associated with underground explosions. Specifically, we present results of a detailed study of coseismic and postseismic surface deformation signals associated with underground nuclear and chemical explosion tests at the Nevada Test Site (NTS). Several interferograms were formed from raw ERS-1/2 radar data covering different time spans and epochs beginning just prior to the last U.S. nuclear tests in 1992 and ending in 1996. These interferograms have yielded information about the nature and duration of the source processes that produced the surface deformations associated with these events. A critical result of this study is that significant post-event surface deformation associated with underground nuclear explosions detonated at depths in excess of 600 meters can be detected using differential radar interferometry. An immediate implication of this finding is that underground nuclear explosions may not need to be captured coseismically by radar images acquired before and after an event in order to be detectable. This has obvious advantages in CTBT monitoring since suspect seismic events--which usually can be located within a 100 km by 100 km area of an ERS-1/2 satellite frame by established seismic methods-can be imaged after the event has been identified and located by existing regional seismic networks. Key Words: InSAR, SLC images, interferogram, synthetic interferogram, ERS-1/2 frame, phase unwrapping, DEM, coseismic, postseismic, source parameters.

Foxall, W; Vincent, P; Walter, W

1999-07-23

320

Waveform analysis of transmissions of opportunity for passive radar  

Microsoft Academic Search

Passive radar utilises electromagnetic radiation already present in the environment in order to detect targets and estimate target parameters. This paper presents a general investigation of the feasibility of this type of radar when the radiation utilised originates from common emitters of opportunity such as commercial radio and television broadcasts. It addresses the problem using waveform design theory and an

Maurice A. Ringer; Gordon J. Frazer

1999-01-01

321

Electrochemical formation of field emitters  

DOEpatents

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

Bernhardt, Anthony F. (Berkeley, CA)

1999-01-01

322

Survey of radar target identification for noise polluted radar measurements  

Microsoft Academic Search

Itpsilas important to develop reliable approach of radar target identification for low signal-to-noise ratio (SNR) situation, especially when the radar is used in battle field. A feature selection method is proposed in this paper. The one nearest-neighbor (1-NN) classifier is used as classifier. The effectiveness of radar target identification based on the methods is investigated in computer simulation for both

Zhou De-Quan

2008-01-01

323

Multi-Gigahertz radar range processing of baseband and RF carrier modulated signals in Tm:YAG  

Microsoft Academic Search

An optical device is described and demonstrated that uses a spatial-spectral holographic material to perform coherent signal processing operations on analog, high-bandwidth optical signals with large time-bandwidth-products. Signal processing is performed as the material records the coherent spectral interference (or cross-power spectrum) of modulated optical signals as a spatial-spectral population grating between electronic transition states. Multiple exposures of processing pulse

K. D. Merkel; R. Krishna Mohan; Z. Cole; T. Chang; A. Olson; W. R. Babbitt

2004-01-01

324

Environmental awareness for sensor and emitter employment  

NASA Astrophysics Data System (ADS)

Environmental Awareness for Sensor and Emitter Employment (EASEE) is a flexible, object-oriented software design for predicting environmental effects on the performance of battlefield sensors and detectability of signal emitters. Its decision-support framework facilitates many sensor and emitter modalities and can be incorporated into battlespace command and control (C2) systems. Other potential applications include immersive simulation, force-on-force simulation, and virtual prototyping of sensor systems and signal-processing algorithms. By identifying and encoding common characteristics of Army problems involving multimodal signal transmission and sensing into a flexible software architecture in the Java programming language, EASEE seeks to provide an application interface enabling rapid integration of diverse signal-generation, propagation, and sensor models that can be implemented in many client-server environments. Its explicit probabilistic modeling of signals, systematic consideration of many complex environmental and mission-related factors affecting signal generation and propagation, and computation of statistical metrics characterizing sensor performance facilitate a highly flexible approach to signal modeling and simulation. EASEE aims to integrate many disparate statistical formulations for modeling and processing many types of signals, including infrared, acoustic, seismic, radiofrequency, and chemical/biological. EASEE includes objects for representing sensor data, inferences for target detection and/or direction, signal transmission and processing, and state information (such as time and place). Various transmission and processing objects are further grouped into platform objects, which fuse data to make various probabilistic predictions of interest. Objects representing atmospheric and terrain environments with varying degrees of fidelity enable modeling of signal generation and propagation in diverse and complex environments.

Yamamoto, Kenneth K.; Wilson, D. Keith

2010-04-01

325

Radar Entomology  

NSDL National Science Digital Library

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

0002-11-30

326

Waveform for Short-Dwell-Time Meteorological Doppler Radars.  

National Technical Information Service (NTIS)

A modulation waveform for meteorological Doppler radars that obtain estimates of radar reflectivity, mean velocity, and Doppler width with very short dwell time is described. The transmitted signal is a sequence of three identical chirp pulses; signal par...

R. G. Strauch

1987-01-01

327

Effect of Temperature Gradient on Thick Film Selective Emitter Emittance  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

328

Radar principles  

NASA Technical Reports Server (NTRS)

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

Sato, Toru

1989-01-01

329

Bistatic coherent radar receiving system  

NASA Astrophysics Data System (ADS)

A coherent-on-receive MTI radar receiver system for use with cooperative or non-cooperative radar transmitters of either the coherent or noncoherent, simple magnatron type and scanning antennas is discussed. The receiver includes coherent digital signal processing with provision for normalizing or compensating phase variations in the transmitter carrier pulses.

Yamano, L. C.

1984-10-01

330

Bistatic coherent radar receiving system  

Microsoft Academic Search

A coherent-on-receive MTI radar receiver system for use with cooperative or non-cooperative radar transmitters of either the coherent or noncoherent, simple magnatron type and scanning antennas is discussed. The receiver includes coherent digital signal processing with provision for normalizing or compensating phase variations in the transmitter carrier pulses.

L. C. Yamano

1984-01-01

331

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

332

A novel radar waveform compatible with communication  

Microsoft Academic Search

Multifunctional radar is a trend in the future. Employing radar system for high data rate, long range, anti-intercepted communication by making use of its wide bandwidth, high power and directing property has been a research hotspot nowadays. Hereinto, radar-communication compatible waveforms design is a key technique. This paper proposes a novel compatible waveform produced by modulating LFM signal by MSK

Xingbo Chen; Xiaomo Wang; Shanfeng Xu; Jing Zhang

2011-01-01

333

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

334

Development of Surveillance and Tracking Radar  

Microsoft Academic Search

A high-resolution surveillance and tracking radar has been recently developed and tested at the Institute of Radio Astronomy. The radar is a monopulse, all-weather radar with mechanical beam steering. It works in a pulse mode, and a coherent FFT-based signal processing is utilized. The radar is equipped with a clutter suppression system and with a Kalman filtering scheme for trajectory

D. M. Vavriv; V. A. Volkov; S. V. Sosnytskiy; A. V. Shevchenko; R. V. Kozhyn; A. A. Kravtsov; M. P. Vasilevskiy; D. I. Zaikin

2006-01-01

335

SAR Ambiguity Study for the Cassini Radar  

NASA Technical Reports Server (NTRS)

The Cassini Radar's synthetic aperture radar (SAR) ambiguity analysis is unique with respect to other spaceborne SAR ambiguity analyses owing to the non-orbiting spacecraft trajectory, asymmetric antenna pattern, and burst mode of data collection. By properly varying the pointing, burst mode timing, and radar parameters along the trajectory this study shows that the signal-to-ambiguity ratio of better than 15 dB can be achieved for all images obtained by the Cassini Radar.

Hensley, Scott; Im, Eastwood; Johnson, William T. K.

1993-01-01

336

Sensitivity of FMCW 95GHz cloud radar for high clouds  

Microsoft Academic Search

Studying the vertical structure of cloud is essential to make better atmospheric modellings for simulations of the global warming. Cloud observation requires very high sensitivity for radar. Although pulse radar is the mainstream of MMCR (millimeter wave cloud radar), FMCW radar has some advantages. FMCW signal has high spatial and time resolution, and enables high durability and cost-performance because all

J. Yamaguchi; T. Takano; T. Nakajima; T. Takamura; H. K. Y. Ohno; Y. Nakanishi; K. Akita; Y. Kawamura; H. A. Futaba; S. Yokote

2006-01-01

337

A Microcomputer-Controlled Pseudo Noise Modulated CW-Radar With SAW-Convolver For Signal Processing  

Microsoft Academic Search

In the past there was a rapid development of new components for matched filtering of signals with large time-bandwidth-product on the basis of surface acoustic waves (SAW). Such components, as there is the SAW-Convolver \\/1\\/, allow the realization of very fast and precise operating distance measurement systems with a minimum of components in the signal processing circuitry. In addition continous

B. Wigger; W. Knapp; E. Besenfelder

1988-01-01

338

Monolithic multinozzle emitters for nanoelectrospray mass spectrometry  

DOEpatents

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

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

2011-09-20

339

Directional borehole radar calibration  

Microsoft Academic Search

We are developing an innovative low-noise directional borehole radar system. Harsh and changing operating environments are a challenge to the low-noise sensitive electronic design. Additionally a system with such high sensitivity is susceptible to temperature changes and to component parameter variations. Therefore a calibration module was developed to calibrate the overall measurement system with a test signal generator. This calibration

O. Borchert; K. Behaimanot; A. Glasmachers

2009-01-01

340

Electrochemical formation of field emitters  

DOEpatents

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

Bernhardt, A.F.

1999-03-16

341

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

NASA Astrophysics Data System (ADS)

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

Reschke, Brent R.; Timperman, Aaron T.

2011-12-01

342

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

343

Range Doppler detection for automotive FMCW radars  

Microsoft Academic Search

The FMCW-Radar-Principle is widely used for automotive radar systems. The basic idea for FMCW-Radars is to generate a linear frequency ramp as transmit signal. The difference frequency between the transmitted and received signal is determined after downconversion. In order to detect range and velocity together, the information, extracted from one frequency ramp, is not enough, because it is ambiguous. Several

Volker Winkler

2007-01-01

344

Range Doppler detection for automotive FMCW radars  

Microsoft Academic Search

The FMCW-radar-principle is widely used for automotive radar systems. The basic idea for FMCW-radars is to generate a linear frequency ramp as transmit signal. The difference frequency between the transmitted and received signal is determined after downconversion. In order to detect range and velocity together, the information, extracted from one frequency ramp, is not enough, because it is ambiguous. Several

Volker Winkler

2007-01-01

345

NASA Experimental Airborne Doppler Radar and Real Time Processor for Wind Shear Detection.  

National Technical Information Service (NTIS)

The topics are presented in viewgraph form and include the following: experimental radar system capabilities; an experimental radar system block diagram; wind shear radar signal and data processor (WRSDP); WRSDP hardware architecture; WRSDP system design ...

P. H. Schaffner M. A. Richards W. R. Jones L. H. Crittenden

1992-01-01

346

Reconfigurable L-Band Radar  

NASA Technical Reports Server (NTRS)

The reconfigurable L-Band radar is an ongoing development at NASA/GSFC that exploits the capability inherently in phased array radar systems with a state-of-the-art data acquisition and real-time processor in order to enable multi-mode measurement techniques in a single radar architecture. The development leverages on the L-Band Imaging Scatterometer, a radar system designed for the development and testing of new radar techniques; and the custom-built DBSAR processor, a highly reconfigurable, high speed data acquisition and processing system. The radar modes currently implemented include scatterometer, synthetic aperture radar, and altimetry; and plans to add new modes such as radiometry and bi-static GNSS signals are being formulated. This development is aimed at enhancing the radar remote sensing capabilities for airborne and spaceborne applications in support of Earth Science and planetary exploration This paper describes the design of the radar and processor systems, explains the operational modes, and discusses preliminary measurements and future plans.

Rincon, Rafael F.

2008-01-01

347

Radar Astronomy.  

National Technical Information Service (NTIS)

A general review of radar astronomy is given. Typical radar systems are described and results cited. Methods of determining elements of orbits and rotation rates of planets are discussed. A proposed test of the Einstein theory of general relativity is des...

G. H. Pettengill I. I. Shapiro

1965-01-01

348

Radar astronomy  

Microsoft Academic Search

Radar Astronomy is a new and growing branch of Astronomy. Although it seems that radio echo studies must be confined to the solar system, they can play an important part in developing our understanding of the Sun and the planets. At the present time these objects are barely detectable by radar techniques and much of the work has been concerned

J. V. Evans

1960-01-01

349

Development of new methods for the ultrasonic inspection of polymer composites based on the use of radar signals (Review)  

Microsoft Academic Search

The existing methods of the ultrasonic inspection of polymer-based composite materials, characterized by high integral ultrasound attenuation, are reviewed. In particular, attention is given to methods based on the principles of optimal signal filtering, including complexly modulated noise-immune frequency- and phase-shift keyed pulses, which make it possible to achieve high sensitivity and resolution in fault detection. Details of the inspection

V. K. Kachanov; D. A. Rapoport; A. V. Mozgovoi

1990-01-01

350

Time reversal, back propagation, matched field processors, correlation receivers, and the principles of radar\\/sonar signal design  

Microsoft Academic Search

Time reversal and backpropagation have been demonstrated in several experiments. Similarly, while matched field processing (MFP) differs in terms of implentation-experimental vs computed replicas-both have two common properties: (i) they are based on a single, spatially coherent signal; and (ii) the conjugate transpose of the Green's function and replica correlation are identical for self-adjoint systems. Hence, the principles for focusing

Arthur Baggeroer

2002-01-01

351

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

Microsoft Academic Search

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

G. C. Gaunaurd; H. C. Strifors

1996-01-01

352

Design of a Multifrequency FMCW Radar  

Microsoft Academic Search

This paper pertains to the design aspects of a multifrequency FMCW radar with emphasis on the engineerig problems involved in its implementation. This radar generates 8 separate FMCW signals which are then additively mixed and radiated. The target return also comprises returns at these frequencies. The signals are then split into their constituents and processed collectively to obtain an extremely

M. Jankiraman; B. J. Wessels; P. van Genderen

1998-01-01

353

Radar target recognition based on fuzzy clustering  

Microsoft Academic Search

A new method of recognizing the aircraft number of a radar target from a narrowband IF signal of non-coherent radar is presented. According to the received narrowband IF echo signal, its autocorrelation matrix is computed. The feature vector is the eigenvalue of the autocorrelation matrix, and the orthogonal transformation is accomplished to remove the unnecessary information in the feature. The

Jiang Jing; Wang Shouyong; Yu Lan; Zuo Delin; Yang Zhaoming; Tang Changwen

1998-01-01

354

Radar waveform selection based on the calculation and application of radar ambiguity functions  

Microsoft Academic Search

The magnitude of the radar ambiguity function for commonly used radar waveforms is calculated and displayed in three-dimensional diagrams. The ambiguity functions are calculated as a function of range delay and Doppler frequency. For a specified clutter environment and a particular radar waveform, the signal-to-clutter ratio for a desired target is calculated. A method to select a radar waveform, given

J. D. Reed

1982-01-01

355

Waveform error analysis for bistatic synthetic aperture radar systems  

Microsoft Academic Search

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

J. W. Adams; T. M. Schifani

1987-01-01

356

Polarimetric ISAR imaging using a coherent ultrawideband random noise radar  

Microsoft Academic Search

An ultrawideband random noise radar operating in the 1 - 2 GHz frequency range has been developed at the University of Nebraska-Lincoln. A unique signal processing procedure is utilized that preserves the phase of a received signal thus making it possible to use this radar as a coherent receiver. This allows the UWB random noise radar to be configured as

Daryl C. Bell; Ram M. Narayanan

1999-01-01

357

Thin-Film Selective Emitter  

NASA Technical Reports Server (NTRS)

Direct conversion of thermal energy into electrical energy using a photovoltaic cell is called thermophotovoltaic energy conversion. One way to make this an efficient process is to have the thermal energy source be an efficient selective emitter of radiation. The emission must be near the band-gap energy of the photovoltaic cell. One possible method to achieve an efficient selective emitter is the use of a thin film of rare-earth oxides. The determination of the efficiency of such an emitter requires analysis of the spectral emittance of the thin film including scattering and reflectance at the vacuum-film and film-substrate interfaces. Emitter efficiencies (power emitted in emission band/total emitted power) in the range 0.35-0.7 are predicted. There is an optimum optical depth to obtain maximum efficiency. High emitter efficiencies are attained only for low (less than 0.05) substrate emittance values, both with and without scattering. The low substrate emittance required for high efficiency limits the choice of substrate materials to highly reflective metals or high-transmission materials such as sapphire.

Chubb, Donald L.; Lowe, Roland A.

1993-01-01

358

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

359

Rare Earth Garnet Selective Emitter.  

National Technical Information Service (NTIS)

Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approximately equal to 0.74, ((4)l(sub 15/2)) - ( (4)l(sub13/2)), for Er-YAG and epsilon(sub lambda) approximately equ...

R. A. Lowe D. L. Chubb S. C. Farmer B. S. Good

1994-01-01

360

GPU Performance Comparison for Accelerated Radar Data Processing  

Microsoft Academic Search

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

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

2011-01-01

361

Emittance growth in intense beams  

SciTech Connect

Recent progress in the study of high-current, low-emittance, charged-particle beams may have a significant influence in the design of future linear accelerators and beam-transport systems for higher brightness applications. Three space-charge-induced rms-emittance-growth mechanisms are now well established: (1) charge-density redistribution, (2) kinetic-energy exchange toward equipartitioning, and (3) coherent instabilities driven by periodic focusing systems. We report the results from a numerical simulation study of emittance in a high-current radio-frequency quadrupole (RFQ) linear accelerator, and present a new semiempirical equation for the observed emittance growth, which agrees well with the emittance growth predicted from numerical simulation codes.

Wangler, T.P.; Mills, R.S.; Crandall, K.R.

1987-03-01

362

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

363

Statistical Pattern Recognition Techniques as Applied to Radar Returns.  

National Technical Information Service (NTIS)

This report presents a summary of the basic principles of pattern recognition and statistical decision theory and applies them to the problem of classifying radar returns. While pattern recognition techniques have been applied to radar signal detection pr...

W. A. Fordon A. A. Fraser

1981-01-01

364

Radar transponder operation with compensation for distortion due to amplitude modulation  

DOEpatents

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

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

2011-01-04

365

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

366

Improvements to RADAR Location Classification  

Microsoft Academic Search

Location estimation has been a backbone for location-aware services as wireless networks and mobile devices are more pervasively available. By operating on the signal strength space, nearest neighbor methods like RADAR have proved to be simple yet effective for location estimation. It has been common to take locations as classes, and then to infer location classes based on signal strength

Zhili Wu; Chun-Hung Li; Joseph K. Ng

2008-01-01

367

Combustion powered thermophotovoltaic emitter system.  

National Technical Information Service (NTIS)

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 opt...

R. S. McHenry

1995-01-01

368

Wavelet radar target classification  

Microsoft Academic Search

Ground-based S-band radars with center frequencies in the 3 GHz range, and bandwidths of about 2 MHz, are currently being considered for the classification\\/identification of targets in the 50 - 250 km range (low signal-to-noise (SNR) environment). Its main drawback is that it is time and computation intensive, and, for targets at long range, it usually requires a number of

Pankaj N. Topiwala; Chojan S. Teng

1995-01-01

369

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

370

Radar range measurements in the atmosphere.  

SciTech Connect

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

Doerry, Armin Walter

2013-02-01

371

Visible Spectrum Incandescent Selective Emitter  

SciTech Connect

The purpose of the work performed was to demonstrate the feasibility of a novel bi-layer selective emitter. Selective emitters are incandescent radiant bodies with emissivities that are substantially larger in a selected part of the radiation spectrum, thereby significantly shifting their radiated spectral distribution from that of a blackbody radiating at the same temperature. The major research objectives involved answering the following questions: (1) What maximum VIS/NIR radiant power and emissivity ratios can be attained at 2650 K? (2) What is the observed emitter body life and how does its performance vary with time? (3) What are the design tradeoffs for a dual heating approach in which both an internally mounted heating coil and electrical resistance self-heating are used? (4) What are the quantitative improvements to be had from utilizing a bi-layer emitter body with a low emissivity inner layer and a partially transmissive outer layer? Two approaches to obtaining selective emissivity were investigated. The first was to utilize large optical scattering within an emitter material with a spectral optical absorption that is much greater within the visible spectrum than that within the NIR. With this approach, an optically thick emitter can radiate almost as if optically thin because essentially, scattering limits the distance below the surface from which significant amounts of internally generated radiation can emerge. The performance of thin emitters was also investigated (for optically thin emitters, spectral emissivity is proportional to spectral absorptivity). These emitters were fabricated from thin mono-layer emitter rods as well as from bi-layer rods with a thin emitter layer mounted on a substrate core. With an initially estimated energy efficiency of almost three times that of standard incandescent bulbs, a number of energy, economic and environmental benefits such as less energy use and cost, reduced CO{sub 2} emissions, and no mercury contamination was initially projected. The work performed provided answers to a number of important questions. The first is that, with the investigated approaches, the maximum sustained emitter efficiencies are about 1.5 times that of a standard incandescent bulb. This was seen to be the case for both thick and thin emitters, and for both mono-layer and bi-layer designs. While observed VIS/NIR ratios represent improvements over standard incandescent bulbs, it does not appear sufficient to overcome higher cost (i.e. up to five times that of the standard bulb) and ensure commercial success. Another result is that high temperatures (i.e. 2650 K) are routinely attainable without platinum electrodes. This is significant for reducing material costs. A novel dual heating arrangement and insulated electrodes were used to attain these temperatures. Another observed characteristic of the emitter was significant grain growth soon after attaining operating temperatures. This is an undesirable characteristic that results in substantially less optical scattering and spectral selectivity, and which significantly limits emitter efficiencies to the values reported. Further work is required to address this problem.

Sonsight Inc.

2004-04-30

372

Radar volcano monitoring system in Iceland  

NASA Astrophysics Data System (ADS)

Weather radars are valuable instruments in monitoring explosive volcanic eruptions. Temporal variations in the eruption strength can be monitored as well as variations in plume and ash dispersal. Strength of the reflected radar signal of a volcanic plume is related to water content and droplet sizes as well as type, shape, amount and the grain size distribution of ash. The Icelandic Meteorological Office (IMO) owns and operates three radars and one more is planned for this radar volcano monitoring system. A fixed position 250 kW C-band weather radar was installed in 1991 in SW-Iceland close to Keflavík International Airport, and upgraded to a doppler radar in 2010. In cooperation with the International Civil Aviation Organization (ICAO), IMO has recently invested in two mobile X-band radars and one fixed position C-band radar. The fixed position 250 kW doppler C-band weather radar was installed in April 2012 at Fljótsdalsheiði, E-Iceland, and in June 2012 IMO received a mobile 65 kW dual-polarization doppler X-band radar. Early in 2013 IMO will acquire another mobile radar of the same type. Explosive volcanic eruptions in Iceland during the past 22 years were monitored by the Keflavík radar: Hekla 1991, Gjálp 1996, Grímsvötn 1998, Hekla 2000, Grímsvötn 2004, Eyjafjallajökull 2010 and Grímsvötn 2011. Additionally, the Grímsvötn 2011 eruption was mointored by a mobile X-band radar on loan from the Italian Civil Protection Authorities. Detailed technical information is presented on the four radars with examples of the information acquired during previous eruptions. This expanded network of radars is expected to give valuable information on future volcanic eruptions in Iceland.

Arason, Þórður; Yeo, Richard F.; Sigurðsson, Geirfinnur S.; Pálmason, Bolli; von Löwis, Sibylle; Nína Petersen, Guðrún; Bjornsson, Halldór

2013-04-01

373

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

374

Large phased-array radars  

SciTech Connect

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

Brookner, D.E.

1988-12-15

375

MIMO radars or is it smart antennas?  

Microsoft Academic Search

Radars were originally designed as detectors of targets. The goal was to transmit a signal with the maximum available power and then observe whether the received signal contained a portion of the transmitted signal. A matched filter was then designed using the transmitted waveform to detect the received signal and based on some statistical hypothesis testing a decision was made

Tapan K. Sarkar; Magdalena Salazar Palma

2010-01-01

376

Photonics for airborne phased array radars  

Microsoft Academic Search

In future generation phased array radars, signal distributions will have to fulfil strict performance criteria. These include high isolation from both electromagnetic interference and crosstalk between module or subarray feeds with increased instantaneous bandwidths, dramatic reduction in size and weight with respect to current radars, and performance compatible with growing requirements such as low phase noise and high dynamic range.

D. Dolfi; D. Mongardien; S. Tonda; M. Schaller; J. Chazelas

2000-01-01

377

Transmitter Noise Cancellation in Monostatic FMCW Radar  

Microsoft Academic Search

Digital leakage cancellation realizes noise cancellation at RF frequency, in addition to suppress leakage signal in FMCW monostatic radar. Noise cancellation mechanism is analyzed with autocorrelation function of noise. The measurement results in Ka band radar test are provided and show the effectiveness

Kaihui LinandYuanxun; Yuanxun Ethan Wang

2006-01-01

378

FMCW Radar Transmitter Based on DDS Synthesis  

Microsoft Academic Search

This paper presents some design problems and aspects of building FMCW radar transmitter based on DDS. Significant parameters of this radar are small targets detection possibility, small resolution cell and high range resolution. It requires resolving a problem of generation microwave signals with excellent linear frequency modulation and very good phase noise performance. One of possible solution is DDS (direct

Slawomir Plata

2006-01-01

379

Pulsed Phase Shifter Improves Doppler Radar  

NASA Technical Reports Server (NTRS)

Ability of microwave Doppler radar to measure velocity of slow moving nearby target is enhanced by pulsed 90 degrees phase shifter in radar transmission line between circulator and antenna. Because of phase shifting, Doppler frequency is detected as modulation on carrier instead of baseband signal. Carrier is amplified and filtered before demodulation, resulting in strong, clean demodulated Doppler for measurement and display.

Kobayashi, H. S.; Shores, P. W.; Rozas, P.

1982-01-01

380

Harmonic automotive radar for VRU classification  

Microsoft Academic Search

A harmonic radar and set of passive transponders are used for detection and identification of vulnerable road users (VRU) in automotive applications. The radar system transmits a signal consisting of two distinct frequency components in the 76-81 GHz band. A small transponder is carried by the VRU. The antenna and the electric circuitry of the transponder are printed on flexible

Jone Saebboe; Ville Viikari; Timo Varpula; Heikki Seppä; Shi Cheng; M. Al-Nuaimi; P. Hallbjorner; A. Rydberg

2009-01-01

381

Spectral moment estimation in MST radars  

NASA Technical Reports Server (NTRS)

Signal processing techniques used in Mesosphere-Stratosphere-Troposphere (MST) radars are reviewed. Techniques which produce good estimates of the total power, frequency shift, and spectral width of the radar power spectra are considered. Non-linear curve fitting, autocovariance, autocorrelation, covariance, and maximum likelihood estimators are discussed.

Woodman, R. F.

1983-01-01

382

Radar System Studies Using Simulation Techniques  

Microsoft Academic Search

Pulse-compression is a technique used in radar to transmit a long pulse while retaining the range resolution of a short pulse. The echo from the target is compressed in the matched filter of the radar receiver and the range resolution becomes equal to the width of the central peak of the autocorrelation function of the transmitted signal. A range tracking

Carl Magnus Thorsteinson

1972-01-01

383

TOA association for handheld UWB radar  

Microsoft Academic Search

Handheld ultra-wideband radars can be used with advantage during rescue, surveillance or security operations by reason that they enable to track targets moving behind walls. The radar signal processing for that purpose represents a complex process with several processing phases. In this paper, the attention is devoted to the estimation of the correct input data for the localization phase. This

Jana Rovnakova; Dusan Kocur

2010-01-01

384

Radar trends to the year 2000  

Microsoft Academic Search

Advancements in electronics are effecting swift changes in radar design features and performance capabilities, including miniaturization, faster signal processing, over-the-horizon range, and electronic (rather than mechanical) antenna scanning. In particular, a few Monolithic Microwave Electronic Circuitry chips can be used, in place of hundreds of conventional circuits, to construct a radar transceiver module, with great attendant reduction of parts counts

Eli Brookner

1987-01-01

385

Study on HPRF Pulsed Doppler Stepped Frequency Radar System  

Microsoft Academic Search

Stepped-frequency radar has the ability of high range resolution. It normally adopts frequency time transformation (IDFT) processing to get the range profile of targets. Alternatively stepped frequency radar can also use time-frequency transformation (DFT) processing, with which it is regarded as a kind of Doppler (PD) radars. Through parametric design and signal processing methods, DFT method can achieve both unambiguous

Ren Li-xiang; Mao Er-ke

2006-01-01

386

Non-contact heart rate tracking using Doppler radar  

Microsoft Academic Search

Non-contact vital signs monitoring system based on Continuous-wave (CW) Doppler radar has been becoming more and more attractive in the field of health care. CW Doppler radar has been extensively studied to extract respiration and heart rates, which are vital for many medical applications. This paper will introduce a radar signal processing method, which is able to extract respiration and

He Tan; Dengyu Qiao; Ye Li

2012-01-01

387

Statistical pattern recognition techniques as applied to radar returns  

Microsoft Academic Search

This report presents a summary of the basic principles of pattern recognition and statistical decision theory and applies them to the problem of classifying radar returns. While pattern recognition techniques have been applied to radar signal detection problems, they have rarely been used in testing hypothesis for classifying radar returns. Two techniques, the parametric Bayes and the non-parametric K-Nearest Neighbor

W. A. Fordon; A. A. Fraser

1981-01-01

388

Millimeter wave noise radar applications: theory and experiment  

Microsoft Academic Search

Noise Radar Technology (NRT) is a radar technology that uses Noise Waveform (NW) as a sounding signal and either correlation reception of NW radar retums that imply the use of a delay line or spectral interferometry method enabling range and velocity measurement without use of a delay line. The Noise Waveform (NW) is known to be an appropriate one for

Konstantin A. Lukin

2001-01-01

389

Rain Clutter Filtering from Radar Data with Discrete Wavelet Transform  

Microsoft Academic Search

Moving weather systems will have a nonzero Doppler response at rate at which the rain droplets are approaching the radar system. The complete data the radar collects contain the returns of both the target and the clutter. The signal processing block in a radar system uses filtering operations to extract the target information while suppressing the clutter. Typically the filters

Ilkka Ellonen; Arto Kaarna

2006-01-01

390

A millimeter-wave radar for train application  

Microsoft Academic Search

A millimeter-wave radar using a spread spectrum technique for train applications has been developed in the 60 GHz band. This radar measures the distance, velocity, azimuth angle, and the magnitude of received signal of each target. The methods for detection are described in this paper. In the experiment, the radar detected the linear shape of trains

Sliinsaku Noda; K. Inomata; Masahiro Watanabe; Tadamasa Fukae; Masanii Tobioka

1999-01-01

391

Influence of information technology on military radar systems  

Microsoft Academic Search

The paper discusses influence of information technology (IT) on military radar systems and how this impacts upon conducting military operations. Applications of new technologies in three basic areas of military radar systems are considered: surveillance and automatic target recognition systems; tracking systems and data and signal processing. Some possible uses of radar data are shown along with how this will

P. M. Jeliazov; M. P. Jeliazov; M. S. Marinov

2004-01-01

392

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

393

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

394

Impact of extremely high speed logic technology on radar performance  

Microsoft Academic Search

Limitations related to the utilization of digital procedures in radar systems are connected with the difference between the throughput rates of the digital devices and the required throughput rate for broadband, multiple-range-gated radar signals. The present investigation is concerned with the feasibility of innovative uses of extremely high speed integrated circuits in radar. The probable technologies for high speed electronics

E. K. Reedy; R. B. Efurd; M. N. Yoder

1982-01-01

395

Coherent multilateral radar processing for precise target geolocation  

Microsoft Academic Search

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

Jen King Jao

2006-01-01

396

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

397

Detection and diagnosis of radar modeling errors using covariance consistency  

Microsoft Academic Search

Often, detection-based tracking algorithms are developed without much regard for the effects of either the radar's analog signal processing or its digital signal-processing algorithms. In this paper, we combine the effects of the radar's signal processing and tracking algorithms to assess the combined effect on covariance consistency of various algorithms. To do this, we first define the terms detection, detection

Andy H. Register; Mahendra Mallik; W. Dale Blair; Chris Burton; Paul Burns

2009-01-01

398

Radar trends to the year 2000  

NASA Astrophysics Data System (ADS)

Advancements in electronics are effecting swift changes in radar design features and performance capabilities, including miniaturization, faster signal processing, over-the-horizon range, and electronic (rather than mechanical) antenna scanning. In particular, a few Monolithic Microwave Electronic Circuitry chips can be used, in place of hundreds of conventional circuits, to construct a radar transceiver module, with great attendant reduction of parts counts and module size and weight. Attention is given to ultralow sidelobe antennas, adaptive array processing, three-dimensional radars, and bistatic military radar systems.

Brookner, Eli

1987-05-01

399

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

400

Radar Roadmap.  

National Technical Information Service (NTIS)

Instrumentation radar has played a very significant role in testing and training for more than 50 years. Along with optics, it has been a major supplier of time space position information (TSPI). With the advent of the Global Positioning System (GPS), the...

1998-01-01

401

Radar nomenclature  

Microsoft Academic Search

Like much of the equipment used by the armed forces, both civil and military radar systems may be allocated an identification resolved from a synonym, mnemonic, project name, number, application notation, or specialised nomenclature and sometimes may even be based upon the whims of an intelligence reporting service. Of these, mnemonics are very popular; whilst of designation systems used by

J. C. Wise

2004-01-01

402

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) [La Jolla, CA

1990-01-01

403

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) [La Jolla, CA

1990-01-01

404

Comparison of alkali ion emitters  

NASA Astrophysics Data System (ADS)

Lithium, Potassium, and Cesium ion sources have been studied using devices based on thermal emission from a Beta Eucryptite structure as possible ion sources for use in satellite charge control. The experiments evaluated the power requirements of the different ion emitters to produce approximately 10 microamps of current and tested the effects of using an Osmium Ruthenium coating to increase the work function of the emitter surface. Lifetime tests of the different ion emitters were also performed. Analysis of the experimental findings showed that lithium ion sources with a lifetime of 93 hours and Potassium ion sources with a lifetime of 44 hours produced acceptable current levels for use in spacecraft charge control devices. Potassium sources produced the necessary current, 10 microamps, at 140 C lower temperature than the Lithium sources. All of the coated sources produced wildly fluctuating currents at the 10 microamp level and were not acceptable for the purpose intended.

Gant, Dean A.

1991-12-01

405

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

406

System design of radar for mine detection  

NASA Astrophysics Data System (ADS)

Mine detection using active radar systems is the subject of a number of research programs both in the US and in Europe. This paper considers the environmental and operational drivers that influence the design of such radar systems. The prime system architectures are time domain and frequency domain configurations and each has its merits. The majority of the ground probing radars used at present are time-domain ultra- wideband radars and their characteristics are well established, while a smaller proportion of radars operate in the frequency domain, using FMCW, stepped frequency or noise modulation. The complexity and cost of the latter type of radar is at present greater than the time-domain radars but theoretically offers a better dynamic range. This paper considers the characteristics of these generic radar systems and the factors that need to be considered in system design. The performance of the antenna significantly affects the overall system and the paper qualitatively discusses this aspect. For GPR, an important technical challenge is associated with achieving a well-defined antenna footprint to maximize the signal to clutter ratio and consideration will be given, in the paper, to time domain array antennas for mine detection. The results of studies carried out during EU funded programs will be reported in this paper. The radar image of the mine depends not only on its construction and on geometry but also on the local environment, hence prior assumptions about the radar spatial signature of the mine may be ill- founded.

Daniels, David J.

1999-10-01

407

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

408

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

409

Radar target identification using multifractal geometry  

NASA Astrophysics Data System (ADS)

The design of a system to distinguish objects from measurements of their radar backscatter signals has been a topic of considerable investigation. In the identification of a particular target out of a library of possible targets, the difficulty is that the radar signals cannot be fed rawly into a classifier. Some signal processing has to be done to generate the signal features for target identification. In this paper, multifractal geometry is applied to address the practical issue of discrimination between fishing boat, growlers (small pieces of glacial ice) and sea scattered signals, which is important for search-and-rescue operation. An efficient box-counting method is used to compute the generalized dimension and the multifractal spectrum of different targets and sea scattered signals. In an effort to support our study, X-band radar measurements were collected and analyzed to determine the separability of sea surface targets and sea scattered signals using the multifractal geometry.

Quach, Ban; Leung, Henry; Lo, Titus K. Y.; Litva, John

1996-06-01

410

Equatorial radar system  

Microsoft Academic Search

A large clear air radar with the sensitivity of an incoherent scatter radar for observing the whole equatorial atmosphere up to 1000 km altitude is now being designed in Japan. The radar, called the Equatorial Radar, will be built in Pontianak, Kalimantan Island, Indonesia (0.03 N, 109.3 E). The system is a 47 MHz monostatic Doppler radar with an active

S. Rukao; T. Tsuda; T. Sato; S. Kato

1989-01-01

411

Radars in space  

NASA Technical Reports Server (NTRS)

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

Delnore, Victor E.

1990-01-01

412

GNU Radio based software-defined FMCW radar for weather surveillance application  

Microsoft Academic Search

In this paper, a GNU Radio based software-defined FMCW (Frequency Modulated — Continuous Wave) radar is studied for weather surveillance application. The FMCW radar that has been gaining popularity due to the use of solid state microwave amplifier to generate a signal source is proposed for the design since the current weather surveillance radar is usually using a pulse-radar type

Aditya Prabaswara; Achmad Munir; Andriyan Bayu Suksmono

2011-01-01

413

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

414

A simulator for the Seasat-A synthetic aperture radar ground support network  

Microsoft Academic Search

The characteristics and capabilities of link measurement and simulation equipment for the NASA ground stations supporting the Seasat-A synthetic aperture radar (SAR) are described. The Spaceflight Tracking and Data Network (STDN) Seasat-A SAR Simulator generates SAR radar and data link signals, including chirp, radar return, pilot, PRN radar timing, and noise components. After injection into and passage through the STDN

S. C. Jones; J. D. Colson; P. J. Grunberger

1978-01-01

415

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

Microsoft Academic Search

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

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

1985-01-01

416

A high-speed and adaptive multichannel data recording system for radar target analysis  

Microsoft Academic Search

Data acquisition is generally a prerequisite condition to conducting practical radar researches such as radar signal detection, automatic target recognition and etc. Because the target returns hold a very short time interval within the radar pulse repetition period, the common data recording systems cannot acquire the target returns efficiently, especially on those radars running in a continuous scanning mode. In

Liu Yang; Wu Jianhui; Fu Qiang; Yu Wenxian

1994-01-01

417

An approach of radar clutter recognition based on higher-order statistics combination  

Microsoft Academic Search

Radar clutter recognition is very useful for optimizing the processing and detection strategy of modern radar signal processing system to improve the performance of the processing system even the whole radar system to the maximum. A new radar clutter recognition approach based on higher-order statistics combination (HOSC) and its modification called weighed HOSC is presented, it can not only classify

Ma Xiaoyan; Fang Xueli; Zhang Ronghua; Xiang Jiabin

2000-01-01

418

Inferring radar mode changes from elementary pulse features using fuzzy ARTMAP classification  

Microsoft Academic Search

A method for radar mode inference using fuzzy ARTMAP classification is presented. In this method elementary radar parameters, pulse width (PW) and pulse repetition interval (PRI) originating from a radar operating in a certain mode is input to a fuzzy ARTMAP classifier. Radar parameters were simulated at different signal-to-noise ratios (SNRs) to train and evaluate the fuzzy ARTMAP classifier without

PIETER F. POTGIETER; JAN C. OLIVIER

2007-01-01

419

Industrialization of Emitters Modules, Part 2.  

National Technical Information Service (NTIS)

This report on the Field Emission Electric Propulsion (FEEP) development program deals with the large emitters clustering and endurance test which have been performed with these emitters modules. The main parts of this test program have been the following...

Bugea Macaign Talmon Valentia

1983-01-01

420

Beta-Eucryptite-Coated Emitter Study.  

National Technical Information Service (NTIS)

Lithium aluminosilicate, when heated from 1000C to 1350C, emits lithium ions from its surface. This study evaluates beta (lithium aluminosilicate) eucryptite as an ion-emitting source. Coated refractory emitters have demonstrated an ion-emitter work funct...

S. Levy

1964-01-01

421

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

422

TRMM radar  

NASA Astrophysics Data System (ADS)

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 objectives, has a minimum measurable rain rate of 0.5 mm/h with a range resolution of 250 m, a horizontal resolution of about 4 km, and a swath width of 220 km. A 128-element active phased array system is adopted to achieve contiguous scanning within the swath. The basic characteristics of BBM were confirmed by experiments. The development of EM started with the cooperation of NASDA and CRL.

Okamoto, Kenichi

1993-05-01

423

TRMM radar  

NASA Technical Reports Server (NTRS)

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 objectives, has a minimum measurable rain rate of 0.5 mm/h with a range resolution of 250 m, a horizontal resolution of about 4 km, and a swath width of 220 km. A 128-element active phased array system is adopted to achieve contiguous scanning within the swath. The basic characteristics of BBM were confirmed by experiments. The development of EM started with the cooperation of NASDA and CRL.

Okamoto, Kenichi

1993-01-01

424

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

425

NASA experimental airborne doppler radar and real time processor for wind shear detection  

NASA Technical Reports Server (NTRS)

The topics are presented in viewgraph form and include the following: experimental radar system capabilities; an experimental radar system block diagram; wind shear radar signal and data processor (WRSDP); WRSDP hardware architecture; WRSDP system design goals; DSP software development tools; OS-9 software development tools; WRSDP digital signal processing; WRSDP display operational modes; WRSDP division of functions; structure of WRSDP signal and data processing algorithms; and the wind shear radar flight experiment.

Schaffner, Philip H.; Richards, Mark A.; Jones, William R.; Crittenden, Lucille H.

1992-01-01

426

Planetary Radar Studies.  

National Technical Information Service (NTIS)

A catalog of lunar and radar anomalies was generated to provide a base for comparison with Venusian radar signatures. The relationships between lunar radar anomalies and regolith processes were investigated, and a consortium was formed to compare lunar an...

T. W. Thompson J. A. Cutts

1981-01-01

427

A FET transceiver suitable for FMCW radars  

Microsoft Academic Search

We present a new FET transceiver suitable for frequency modulated continuous wave (FMCW) radars. The circuit obviates the need for dual antennas, a circulator, or a coupler for the separation of the transmit and receive signal paths. A FET is used simultaneously as an amplifier for the transmitted signal and as a resistive mixer for the received signal. At the

Klas Yhland; Christian Fager

2000-01-01

428

Airborne Differential Doppler Weather Radar  

NASA Technical Reports Server (NTRS)

The Precipitation Radar aboard the Tropical Rain Measuring Mission (TRMM) Satellite has shown the potential for spaceborne sensing of snow and rain by means of an incoherent pulsed radar operating at 13.8 GHz. The primary advantage of radar relative to passive instruments arises from the fact that the radar can image the 3-dimensional structure of storms. As a consequence, the radar data can be used to determine the vertical rain structure, rain type (convective/stratiform) effective storm height, and location of the melting layer. The radar, moreover, can be used to detect snow and improve the estimation of rain rate over land. To move toward spaceborne weather radars that can be deployed routinely as part of an instrument set consisting of passive and active sensors will require the development of less expensive, lighter-weight radars that consume less power. At the same time, the addition of a second frequency and an upgrade to Doppler capability are features that are needed to retrieve information on the characteristics of the drop size distribution, vertical air motion and storm dynamics. One approach to the problem is to use a single broad-band transmitter-receiver and antenna where two narrow-band frequencies are spaced apart by 5% to 10% of the center frequency. Use of Ka-band frequencies (26.5 GHz - 40 GHz) affords two advantages: adequate spatial resolution can be attained with a relatively small antenna and the differential reflectivity and mean Doppler signals are directly related to the median mass diameter of the snow and raindrop size distributions. The differential mean Doppler signal has the additional property that this quantity depends only on that part of the radial speed of the hydrometeors that is drop-size dependent. In principle, the mean and differential mean Doppler from a near-nadir viewing radar can be used to retrieve vertical air motion as well as the total mean radial velocity. In the paper, we present theoretical calculations for the differential reflectivity and Doppler as functions of the center frequency, frequency difference, and median mass diameter. For a fixed pair of frequencies, the detectability of the differential signals can be expressed as the number of independent samples required to detect rain or snow with a particular median mass diameter. Because sampling numbers on the order of 1000 are needed to detect the differential signal over a range of size distributions, the instrument must be confined to a near-nadir, narrow swath. Radar measurements from a zenith directed radar operated at 9.1 GHz and 10 GHz are used to investigate the qualitative characteristics of the differential signals. Disdrometer and rain gauge data taken at the surface, just below the radar, are used to test whether the differential signals can be used to estimate characteristics of the raindrop size distribution.

Meneghini, R.; Bidwell, S.; Liao, L.; Rincon, R.; Heymsfield, G.; Hildebrand, Peter H. (Technical Monitor)

2001-01-01

429

Design and analysis of Costas\\/PSK RF stealth signal waveform  

Microsoft Academic Search

Radio frequency (RF) stealth radar signal waveform design is an important issue in design of modern radar systems. The Costas\\/PSK radar signal waveform is designed and their RF stealth performance is analyzed. First, the FSK FH and PSK continuous wave radar are introduced differently. Second, the FSK\\/PSK continuous wave radar is constructed and its performance is analyzed. Lastly, five kinds

Yang Hongbing; Zhou Jianjiang; Wang Fei; Zhang Zhenkai

2011-01-01

430

Model-Based Radar Power Calculations for Ultra-Wideband (UWB) Synthetic Aperture Radar (SAR).  

National Technical Information Service (NTIS)

In this study, we establish a relationship between the radar transmitted power, the target signature and the signal-to-noise ratio required for a specific target detection performance in a radar system. While this relationship can be easily derived from t...

T. Dogaru

2013-01-01

431

Wavelet based hierarchical coding scheme for radar image compression  

NASA Astrophysics Data System (ADS)

This paper presents a wavelet based hierarchical coding scheme for radar image compression. Radar signal is firstly quantized to digital signal, and reorganized as raster-scanned image according to radar's repeated period frequency. After reorganization, the reformed image is decomposed to image blocks with different frequency band by 2-D wavelet transformation, each block is quantized and coded by the Huffman coding scheme. A demonstrating system is developed, showing that under the requirement of real time processing, the compression ratio can be very high, while with no significant loss of target signal in restored radar image.

Sheng, Wen; Jiao, Xiaoli; He, Jifeng

2007-11-01

432

Downhole pulse radar  

SciTech Connect

This patent describes a downhole radar tool for use with a system for detecting and locating fractures in a geological formation near a borehole. The tool comprises: a generally cylindrical housing; transmitter means; transmitting antenna means; receiving antenna means; isolator means; signal processing means; wherein each of the transmitting and receiving antenna means is a directional antenna comprising: a reflector antenna; a cylindrical pipe; dielectric material filling the electromagnetically active region, the material having a dielectric constant within the range of 20 to 150.

Chang, H.T.

1989-03-21

433

Analysis of a borehole radar in cross-hole mode  

Microsoft Academic Search

A theoretical approach to cross-hole radar measurements is presented. An approximate analytical form for the current distribution on an antenna in a borehole is derived, and the theoretical receiving signal of the borehole radar in the cross-hole measurement is calculated. Theory is compared in the time-domain with the measured borehole radar signal obtained in a salt deposit. The radiation pattern

Motoyuki Sato; Rudolf Thierbach

1991-01-01

434

Automatic emittance measurement at the ATF  

SciTech Connect

An automatic emittance measurement system to characterize the transverse emittance of the electron beam produced by the BNL photocathode electron gun is described. The system utilize a VAX workstation and a Spiricon beam analyzer. A operator window (created through the Vista control software package) controls the emittance measurement system and the graphic presentation of the results. Quadrupole variation method is used for the ATF automatic emittance measurement system. A simple emittance formula was derived to study the performance of the quadrupole variation method, and compared with the ATF experimental data is also presented.

Wang, X.J.; Malone, R.; Batchelor, K.; Ben-Zvi, I.

1993-07-01

435

Radar images of the earth from space  

NASA Technical Reports Server (NTRS)

The operational principles and imagery available from microwave SAR radars for earth observations from aircraft, the Shuttle, and Seasat are explored. Using microwave frequencies is noted to offer imagery access in day or night, all-weather conditions. SAR radar functions by obtaining a series of reflected signals over a single path, with data processing combining the echoes into an image corresponding to what may be obtained with a large antenna. A stable, reference signal is added to the incoming signals in order to establish the phase and amplitude of echoes. Because the wavelengths of the images can be precisely controlled, Doppler shifts can be detected, thus allowing point by point scattering analysis in two-dimensions. The Shuttle SIR-A and the Seasat radar feature a ground resolution of 25 m. Applications of the satellite systems to terrain, ice mapping, and for a Venus radar mapper mission are described.

Elachi, C.

1982-01-01

436

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

437

Metamaterial selective emitters for photodiodes  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

438

Ambiguity analysis of PANDORA multifrequency FMCW\\/SFCW radar  

Microsoft Academic Search

This paper pertains to the design aspects of a multifrequency FMCW\\/SFCW radar with emphasis on the engineering problems involved in its implementation. The paper mostly discusses the FMCW mode of operation. This system can also be used for generating SFCW signals. The implications in this mode are also examined. In the FMCW mode, this radar generates 8 separate FMCW signals

M. Jankiraman; E. W. De Jong; P. Van Genderen

2000-01-01

439

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

440

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

441

Target Detection with Adaptive Power Regression Thresholding 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 performance and system capability. This paper considers a new approach to solve the target detection problem in a complex HF radar signal environment. It uses a

A. L. Dzvonkovskaya; H. Rohling

2006-01-01

442

On energy potential of millimeter-wave radar  

Microsoft Academic Search

One of the most serious problems of a short-pulse millimeter (MM) wave radar is deficit of its energy potential. The radar range upper limit of about a few kilometers is caused mostly by two factors: (1) low energy of transmitting signal pulses restricted by generator overheating or breakdown of waveguiding structures; and (2) decreasing of signal energy received because of

B. A. Rozanov; G. V. Cheslavsky

1998-01-01

443

A continuous-wave (CW) radar for gait analysis  

Microsoft Academic Search

A fully coherent, continuous-wave (CW) radar operating near 10.5 GHz has been developed to record the radar signature corresponding to the walking human gait. The received signal is the sum of Doppler shifted signals reflected from the various parts of the moving body. Since the legs, arms, and torso all move at different relative velocities throughout the gait cycle, the

Jonathan L. Geisheimer; William S. Marshall; Eugene Greneker

2001-01-01

444

Radar assisted passive DF tracking  

NASA Astrophysics Data System (ADS)

The time history of bearing data obtained from microwave DF systems at separated sites is used to calculate the position and velocity of a microwave emitter. A Kalman filter tracking algorithm is presented and used in deriving smoothed position and velocity estimates from simulated bearing measurements received at separated DF sites. It is shown that the error statistics of the bearing measurement data can be modified; nonmaneuvering tracks are then analyzed. The inclusion of radar measurements in order to improve the tracking performance shows that care must be exercised when combining two sets of range data unless the range data is accurately modeled. The algorithm involves a foure-element polar state vector filter that is transformed to Cartesian coordinates for the linear extrapolation stage.

Farrow, R. S.

445

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

446

Topographical Mapping With Synthetic-Aperture Radar  

NASA Technical Reports Server (NTRS)

Interferometric side-looking synthetic-aperture radar shows promise for high-resolution topographical mapping of terrain. Airplane carries two radar antennas. Radar signal transmitted by right antenna, reflected from ground received by both antennas. Amplitudes and phases of received signals recorded and processed separately to yield two 10-m-resolution amplitude-and-phase images of illuminated terrain. Two images mathematically combined point by point to obtain signal image containing interference fringes: phase at each location of image is difference between phases in two signals and amplitude at each location is project of amplitudes of two signals. Theoretically, technique has potential to attain a root-mean-square (rms) altitude error as small as 2 m.

Zebker, Howard A.; Goldstein, Richard M.

1988-01-01

447

International Radar Symposium, Bangalore, India, October 9-12, 1983, Proceedings  

NASA Astrophysics Data System (ADS)

Current developments in the theory, design, and application of radar devices are discussed in reviews and reports and illustrated with diagrams, drawings, graphs, and photographs. Topics examined include reflector antennas and feeds; CFAR and adaptive processing; antenna arrays; signal processing; radar subsystems; cluter; radar R&D efforts in India; MTI, Doppler, and MTD processing; microwave components; and tracking. Consideration is given to electromagnetics, special types of radar systems, search and surveillance radars, simulation and modeling, civilian applications, and systems-engineering aspects.

448

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

449

Doppler synthetic aperture radar imaging  

NASA Astrophysics Data System (ADS)

We consider synthetic aperture radar system using ultra-narrowband continuous waveforms, which we refer to as Doppler Synthetic Aperture Radar (DSAR). We present a novel image formation method for bi-static DSAR. Our method first correlates the received signal with a scaled or frequency-shifted version of the transmitted signal over a finite time window, and then uses microlocal analysis to reconstruct the scene by a filtered-backprojection of the correlated signals. Our approach can be used under non-ideal imaging scenarios such as arbitrary flight trajectories and non-flat topography. Furthermore, it is an analytic reconstruction technique which can be made computationally efficient. We present numerical experiments to demonstrate the performance of the proposed method.

Wang, Ling; Yazici, Birsen

2011-05-01

450

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

451

Analysis of experimental NRL radar altimeter data  

NASA Technical Reports Server (NTRS)

An X-band radar capable of continuously variable transmitted pulse durations down to 1 nsec is being flown to investigate the interaction of radar altimeter signals with the sea surface. There is good agreement between the observed radar altimeter leading edge rise time for a 1-nsec transmitted pulse and the rise time predicted from the radar parameters and the sea state determined by a laser profilometer. Using a threshold tracker on 29-pulse averages for a transmitted pulse of 24 nsec, it was found that the range noise varied linearly with the power level of the threshold over a considerable range. The altimeter range quantization was 9.35 cm, and a minimum range noise of 3.9 cm was obtained. A comparison of pulse-to-pulse correlation observed in the radar data with that predicted by a Monte Carlo simulation is used to obtain a measure of sea surface scatterer motion.

Walsh, E. J.

1974-01-01

452

Transverse Emittance Reduction with Tapered Foil  

SciTech Connect

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

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

2011-12-09

453

Equatorial Radar System.  

National Technical Information Service (NTIS)

A large clear air radar with the sensitivity of an incoherent scatter radar for observing the whole equatorial atmosphere up to 1000 km altitude is now being designed in Japan. The radar, called the Equatorial Radar, will be built in Pontianak, Kalimantan...

S. Rukao T. Tsuda T. Sato S. Kato

1989-01-01

454

Wind shear radar simulation  

NASA Technical Reports Server (NTRS)

Viewgraphs used in a presentation on wind shear radar simulation are given. Information on a microburst model of radar reflectivity and wind velocity, radar pulse output, the calculation of radar return, microburst power spectrum, and simulation plans are given. A question and answer session is transcribed.

Britt, Charles L.

1988-01-01

455

Architecture for a 1-GHz Digital RADAR  

NASA Technical Reports Server (NTRS)

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

Mallik, Udayan

2011-01-01

456

Single-walled carbon nanotube thin film emitter-detector integrated optoelectronic device.  

PubMed

We use the suspended single-walled carbon nanotube (SWNT) thin film technology to assemble the first prototype of an integrated optoelectronic SWNT device, a SWNT optocoupler in which a SWNT emitter and a SWNT detector couple two electrical circuits by the transmission of a signal through the optical channel. Our experiments show that the integrated SWNT emitter/SWNT detector is an ideal couple in which the broadband wavelength character of the emission matches the broadband detection capabilities. PMID:18598090

Itkis, Mikhail E; Yu, Aiping; Haddon, Robert C

2008-08-01

457

CESM: A new category of radar ECCM  

NASA Astrophysics Data System (ADS)

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

Johnston, Stephen L.

1995-02-01

458

Clutter Cancellation Techniques for Use in a Space-Based Radar System.  

National Technical Information Service (NTIS)

The ability of a space-based radar surveillance system to obtain target information from a clutter corrupted radar echo signal is dependent on the clutter cancellation technique employed. To thoroughly understand the nature of clutter so as to efficiently...

J. DeVenuto

1983-01-01

459

Semi-Annual Technical Report for the Common Affordable Radar Processor (CARP).  

National Technical Information Service (NTIS)

The Office of Naval Research (ONR) Surface/Aerospace Surveillance technology program is conducting technology investigations and development of advanced radar signal and control processor technology for current and planned radar systems. The 'Common Affor...

2005-01-01

460

Nonlinear polarisation-vector translation in radar systems - A promising concept for real-time polarisation-vector signal processing via a single-notch polarisation suppression filter  

NASA Astrophysics Data System (ADS)

Until fairly recently, little attention has been given to the utilization of information contained within the polarization states of back-scattered signals relative to the polarization state of the transmitted signal. The same situation exists with respect to the utilization of information contained with respect to the utilization of information contained within the polarization state of interference signals. However, studies conducted by Poelman and Guy (1984) have been concerned with the possibility to achieve useful improvements in the ability to detect targets in adverse environments by applying signal processing in the polarization domain. This type of signal processing has the aim to improve the ratio of average target signal power to average unwanted signal power. An appropriate concept for doing this has been called 'virtual polarization adaptation' (VPA). The considered process has been improved by extending the VPA concept via the adaptive multinotch logic-product (MLP) polarization suppression filter and the adaptive linear polarization-vector translation (PVT) process.

Poelman, A. J.; Guy, J. R. F.

1984-08-01

461

Space Radar Image of Long Island Optical/Radar  

NASA Technical Reports Server (NTRS)

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

1994-01-01

462

Detecting and mitigating wind turbine clutter for airspace radar systems.  

PubMed

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

Wang, Wen-Qin

2013-01-01

463

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

464

Thermophotovoltaic Generation with Microstructured Tungsten Selective Emitters  

NASA Astrophysics Data System (ADS)

To accomplish a good spectral matching between an emitter and photovoltaic cells, two-dimensional surface-relief gratings with a period of 1.0 - 1.2 ?m composed of rectangular microcavities were fabricated on single crystalline W substrates as a selective emitter for thermophotovoltaic generation. The emitters displayed strong emission in the near infrared region where narrow-bandgap photovoltaic cells could efficiently convert photons into electricity. The enhancement of thermal emission was attributed to the microcavity effect. Thermophotovoltaic generation tests were carried out with different kinds of emitters. The W gratings showed more than two-times higher generation efficiency when compared to a SiC emitter. Optical constants of W at high temperatures were investigated by ellipsometry, and it was shown that spectral emissivity of the emitters depended on their temperatures especially in the infrared region.

Sai, Hitoshi; Kamikawa, Takahiro; Kanamori, Yoshiaki; Hane, Kazuhiro; Yugami, Hiroo; Yamaguchi, Masafumi

2004-11-01

465

Emittance, surface structure, and electron emission  

NASA Astrophysics Data System (ADS)

The emittance of high brightness electron sources, particularly field emitters and photocathodes but also thermionic sources, is increased by surface roughness on the emitter. Such structure causes local field enhancement and complicates both the prediction of emittance and the underlying emission models on which such predictions depend. In the present work, a method to find the emission trajectories near regions of high field enhancement is given and applied to emittance predictions for field, photo, and thermal emission for an analytically tractable hemispherical model. The dependence of the emittance on current density, spatial variation, and acceleration close to the emission site is identified and the impact of space charge discussed. The methodology is extensible to field emission from close-spaced wirelike structures, in particular, and extensions to that configuration are discussed. The models have application to electron sources for high frequency vacuum electronics, high power microwave devices, and free-electron lasers.

Jensen, Kevin L.; Shiffler, Donald A.; Petillo, John J.; Pan, Zhigang; Luginsland, John W.

2014-04-01

466

Mutual interference between many similar radars operating in physical proximity  

Microsoft Academic Search

A modification to the radar coherent pulse train signal was developed, which enables the signal reflected from a target to be extracted from the mutual interference among neighboring transmitters. This signal enables interference to be suppressed, under specific delays, regardless of the interference signal strength. A further advantage of this signal is its relatively simple processing by an I and

Moshe Levin

1989-01-01

467

Radar sensing of petroleum seepage gases. Final report  

SciTech Connect

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

Hemenway, D.F.; Hansen, J.P.; George, E.G.

1993-01-17

468

Design, fabrication, and application of precise SAW delay lines used in an FMCW radar system  

Microsoft Academic Search

An inexpensive frequency-modulated continuous-wave (FMCW) radar system is presented in this paper, which, nevertheless, meets all industrial requirements. The FMCW radar uses a low-cost nonlinear voltage-controlled oscillator (VCO), operating at an IF of 2.45 GHz to generate the frequency modulation of the radar system. This VCO signal is applied twice, first to generate the radar transmitter signal at 24 GHz,

Leonhard Reindl; Clemens C. W. Ruppel; Stefan Berek; Ulrich Knauer; Martin Vossiek; Patric Heide; Lutz Oréans

2001-01-01

469

Highly Integrated Radar Sensor-on-Chip  

NASA Astrophysics Data System (ADS)

A highly integrated 24 GHz radar sensor is presented, based on a Radio Frequency Integrated Circuit (RFIC) which was specifically developed for a Frequency Modulated Shift Keying (FMSK) based Radar system design. Antenna, waveform, the Radio Frequency (RF) and Digital Signal Processor (DSP) module, the software design, cost and performance aspects will be described. The significant technical and economical advantages of the implemented Silicon-Germanium (SiGe) Bipolar CMOS (BiCMOS) transceiver are demonstrated. Some automotive and other applications based on this technology and new radar system design will be explained.

Mende, Ralph

2012-05-01

470

Determination of the sources of radar scattering  

NASA Technical Reports Server (NTRS)

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

Moore, R. K.; Zoughi, R.

1984-01-01

471

Radar target signature program performance specification  

NASA Astrophysics Data System (ADS)

This report is a Program Performance Specification (PPS) for a digital computer program that calculates the radar signatures of ships. The PPS will be used to guide the program through three development phases and acceptance testing. The primary objectives of the program are accuracy, flexibility of application, ease of modeling, and portability. The ship is modeled by identifying and defining all the geometrical shapes which cause radar scattering and coherently adding the signals from all the appropriate ones. The program will handle far-field, near-field, and bistatic geometries, antenna patterns, radar absorbing material, and high range resolution effects.

Toothman, H. L.

1981-06-01

472

Emittance Growth in the NLCTA First Chicane  

SciTech Connect

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

Sun, Yipeng; Adolphsen, Chris; /SLAC

2011-08-19

473

Arsenic emitter high-performance transistor  

Microsoft Academic Search

Silicon n-p-n transistors with gain-bandwidth, fT, of 13 GHz and current gain ? of 280 have been fabricated by using arsenic capsule diffusion to produce the emitter region. Devices have been fabricated With the same epitaxial and diffusion processes up to emitter diffusion, and then emitter regions were formed by either arsenic or phosphorus diffusion. For the same mask geometry,

H. N. Ghosh; A. S. Oberai; M. B. Vora; J. J. Chang; M. L. Joshi; T. H. Yeh

1970-01-01

474

A transceiver module of the Mu radar  

NASA Technical Reports Server (NTRS)

The transceiver (TR) module of a middle and upper atmospheric radar is described. The TR module used in the radar is mainly composed of two units: a mixer (MIX unit) and a power amplifier (PA unit). The former generates the RF wave for transmission and converts the received echo to the IF signal. A 41.5-MHz local signal fed to mixers passes through a digitally controlled 8-bit phase shifter which can change its value up to 1,000 times in a second, so that the MU radar has the ability to steer its antenna direction quickly and flexibly. The MIX unit also contains a buffer amplifier and a gate for the transmitting signal and preamplifier for the received one whose noise figure is less than 5 dB. The PA unit amplifies the RF signal supplied from the MIX unit up to 63.7 dBm (2350 W), and feeds it to the crossed Yagi antenna.

Kato, S.; Ogawa, T.; Tsuda, T.; Sato, T.; Kimura, I.; Fukao, S.

1983-01-01

475

Broadband synthetic aperture borehole radar interferometry  

Microsoft Academic Search

Trials in mines have established that wideband VHF borehole radars (BHR), working in the 10–100-MHz band, can be used to probe the rockmass between boreholes over ranges from <5 m to as much as 150 m with submeter resolution. There is evidence that ore bodies reflect these radar signals both specularly and diffusely, much as the ground\\/air interface does when

I. Mason; N. Osman; Q. Liu; C. Simmat; M. Li

2001-01-01

476

Acoustic Radar Employing Particle Velocity Sensors  

Microsoft Academic Search

\\u000a A concept, practical realization and applications of a passive acoustic radar for automatic localization and tracking of sound\\u000a sources were presented in the paper. The device consists of the new kind of multichannel miniature sound intensity sensors\\u000a and a group of digital signal processing algorithms. Contrary to active radars, it does not emit a scanning beam but after\\u000a receiving surroundings

Józef Kotus; Andrzej Czy?ewski

477

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

478

Directional emittance corrections for thermal infrared imaging  

NASA Technical Reports Server (NTRS)

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.

1992-01-01

479

One dimension high range resolution profile of terahertz radar  

NASA Astrophysics Data System (ADS)

Step frequency signal is one of the more commonly used radar signal for high range resolution, it commonly used in radar target recognition. The wavelength of Terahertz signal is shorter than that of the microwave, so it is easy to realize the high range resolution. The paper first introduces the step frequency signal to obtain the one-dimensional distance image, and analyze the principle of high resolution range profiles of step frequency radar. Then, the 0.2THz step frequency radar systems are introduced. Finally, the high resolution range profiles are achieved by the simulation of Matlab. The simulation results show that the step frequency THz radar can reach centimeter level high resolution on stationary targets. For moving targets exist distance divergence and coupling shift. With greater speed, the greater the distortion.

Liang, Meiyan; Zeng, Bangze; Zhang, Cunlin; Zhao, Yuejin

2012-12-01

480

Optimal detection and estimation in FMCW radar  

Microsoft Academic Search

The paper is mainly concerned with detection of an accelerating target echo by FMCW radar. The processed signal is modeled as a polynomial phase signal, contaminated either by white or colored additive Gaussian noise. Obtained tests, optimal in the Neyman-Pearson sense, are linked with the maximum likelihood estimation procedures dealt with in earlier papers. An example shows the importance of

A. Wojtkiewicz; Rafal Rytel-Andrianik

2002-01-01

481

Electromagnetic logging technique based on borehole radar  

Microsoft Academic Search

An electromagnetic logging technique based on borehole radar is introduced in this paper. The tool consists of one transmitter and two receivers, which can be used to cancel the effect of the antenna characteristics by taking the ratio of two receiver signals. Since receiver signals measured in the time domain can be converted into the frequency domain by Fourier transformation,

Sixin Liu; Motoyuki Sato

2002-01-01

482

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

483

Testing of fillet emitter structures with well defined emitter-to-gate spacings  

Microsoft Academic Search

Vertical metal edge emitter arrays with well defined emitter-to-gate separations have been fabricated. Preliminary tests are reported on the operation of these cylindrical emitter tips. The emitter-to-gate spacing is determined by the thickness of a deposited layer which can also serve as a current limiting resistor. Current limiting resistors can also be formed by a self aligned etch of the

D. B. King; J. G. Fleming

1996-01-01

484

A novel emitter-sharpened double-gate race-track-shaped field emitter structure  

Microsoft Academic Search

In this paper, a new emitter-sharpened double-gate race-track-shaped field emitter structure is reported. The race-track-shaped edge emission with double-gate control is used to provide high uniformity FEAs over a large area without the need of expensive submicron technology. In order to minimize the gate current, which is detrimental to the field emitter performance, an emitter-sharpened structure is used. Experimental results

Baoping Wang; Zhongping Huang; Johnny K. O. Sin; Vincent M. C. Poon; Yongming Tang; Chen Wang; Kunxing Xue; Linsu Tong

1999-01-01

485

SMAP RADAR Processing and Calibration  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

486

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

487

Fifty years of radar  

NASA Astrophysics Data System (ADS)

A development history of radar technology is presented, with attention to the driving of radar system design advances by the emergence of such weapon systems as long range aircraft and cruise missiles in World War II and the range of current applications for state-of-the-art radar techniques. The applications noted encompass over-the-horizon backscatter radars for aircraft detection at 500-1800 nmi ranges, ultralow sidelobe antenna military radars, a long range, frequency scanning three-dimensional S-band radar, a shipborne phased array radar for the collection of exoatmospheric and endoatmospheric data on ballistic missile reentry vehicles, multimission/multimode X-band fighter aircraft radars, and phased array air defense radars.

Skolnik, M. I.

1985-02-01

488

Radar images analysis for scattering surfaces characterization  

NASA Astrophysics Data System (ADS)

According to the different problems and techniques related to the detection and recognition of airplanes and vehicles moving on the Airport surface, the present work mainly deals with the processing of images gathered by a high-resolution radar sensor. The radar images used to test the investigated algorithms are relative to sequence of images obtained in some field experiments carried out by the Electronic Engineering Department of the University of Florence. The radar is the Ka band radar operating in the'Leonardo da Vinci' Airport in Fiumicino (Rome). The images obtained from the radar scan converter are digitized and putted in x, y, (pixel) co- ordinates. For a correct matching of the images, these are corrected in true geometrical co-ordinates (meters) on the basis of fixed points on an airport map. Correlating the airplane 2-D multipoint template with actual radar images, the value of the signal in the points involved in the template can be extracted. Results for a lot of observation show a typical response for the main section of the fuselage and the wings. For the fuselage, the back-scattered echo is low at the prow, became larger near the center on the aircraft and than it decrease again toward the tail. For the wings the signal is growing with a pretty regular slope from the fuselage to the tips, where the signal is the strongest.

Piazza, Enrico

1998-10-01

489

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

490

Improving the Fermilab booster emittance  

SciTech Connect

Demand of high luminosity in the Tevatron collider in Fermilab makes the small beam emittance coming out of the 8 GeV Booster a highly desirable feature. This is because Booster bunches with small emittance, when eventually coalesced into Main Ring bunches, will ensure a high luminosity in the collider. Efforts have been made to identify factors limiting the phase space density in both transverse and longitudinal dimensions. The experimental result points to space charge induced tune spread at low energy as the main factor limiting the transverse phase space density, and the space charge induced phase space dilution at transition and longitudinal coupled bunch instability as the factors limiting the longitudinal phase space density. To counteract these factors, a set of harmonic correction sextupoles and skew sextupoles were implemented to reduce the third order resonances in the transverse case. In the longitudinal case a ..gamma../sub t/-jump system was implemented to ease the bunch tumbling after transition, and various schemes to damp the longitudinal coupled bunch instability are either implemented or being reviewed. Future plans and efforts will be mentioned briefly at the end of this article. 3 refs., 8 figs., 1 tab.

Chao, Y.; Crisp, J.; Holmes, S.; Lackey, J.; Merz, W.

1988-06-09

491

Chemical regeneration of emitter surface increases thermionic diode life  

NASA Technical Reports Server (NTRS)

Chemical regeneration of sublimated emitter electrode increases the operating efficiency and life of thermionic diodes. A gas which forms chemical compounds with the sublimated emitter material is introduced into the space between the emitter and the collector. The compounds migrate to the emitter where they decompose and redeposit the emitter material.

Breiteieser, R.

1966-01-01

492

Analysis of a borehole radar in cross-hole mode  

SciTech Connect

In this paper, the authors present a theoretical approach to the cross-hole radar measurements. An approximate analytical form for the current distribution on an antenna in a borehole is derived and the theoretical receiving signal of borehole radar in the crosshole measurement is calculated. Theory is compared in the time-domain with the measured borehole radar signal obtained in a salt deposit. The radiation pattern of a borehole radar excited by the pulse is discussed. The accuracy of tomographic analysis, which is often applied to the cross-hole radar measurements, is strongly governed by this radiation pattern. The authors found that in practice, most borehole radars have a pattern of a {lambda}/2 dipole antenna. However, the authors pointed out that the radiation pattern can be deformed by short pulse excitation, loading by the surrounding media, and coupling to the logging cable.

Sato, M. (Dept. of Resources Engineering, Tohoku Univ., Sendai 980 (JP)); Thierbach, R. (Geological Survey of Lower Saxony, Hannover (DE))

1991-11-01