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1

Hybrid radar emitter recognition based on rough k-means classifier and relevance vector machine.  

PubMed

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

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

2013-01-01

2

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

PubMed Central

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

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

2013-01-01

3

ETANN hardware implementation for radar emitter identification  

NASA Astrophysics Data System (ADS)

This study investigated classification of 30 radar emitters with 16 signal features using Intel's 80170NX chip, the Electronically Trainable Analog Neural Network (ETANN). Software tools were developed to characterize the ETANN sigmoidal transfer function for use in a custom simulator, known as Neural Graphics. Neural Graphics operates on a Silicon Graphics workstation. The Intel Neural Network Training System simulators were used in early experiments, but were found to be inefficient in training on data used in this research. Using a modified Neural Graphics simulator, single chip and multi-chip experiments were performed to provide benchmark results prior to performing chip-in-loop training. By maximizing off-chip training accuracy, the need for on-chip training is minimized; therefore, the device life is prolonged. Several single chip and multi-chip configurations were tried; the final architecture which produced the maximum on-chip classification accuracy was a hierarchical network. The maximum on-chip classification accuracy for a single chip implementation of 30 classes without chip-in-loop training was 83 percent. Again without chip-in-loop training, the maximum on-chip classification accuracy for a hierarchical configuration with the 30-class problem was 87 percent.

Calvin, James B., Jr.

1992-12-01

4

Development of random signal radars  

Microsoft Academic Search

Development of random signal radar (RSR) over the past 30 years is described. Conventional methods of implementing RSR are summarized such as correlation, spectrum analysis, and anticorrelation. Some typical RSR systems are introduced, for example, noise frequency modulation CW radar, random binary phase-coded CW radar, etc., and their merits and demerits are also pointed out. Finally, RSR development trends are

Guosui Liu; Hong Gu; Weimin Su

1999-01-01

5

Interception of LPI radar signals  

Microsoft Academic Search

The interception problem is reviewed, an LPI radar design is examined and the performance of intercept receivers of the future is considered. The receiver needed to intercept LPI signals must respond across a broad band and provide noncoherent integration capabilities over times comparable to the coherent (or noncoherent) integration times used by radars. One useful receiver design is the rapidly

Gerd Schrick; R. G. Wiley

1990-01-01

6

Ghost signals in Allison emittance scanners  

SciTech Connect

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

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

2004-12-01

7

Ghost Signals In Allison Emittance Scanners  

SciTech Connect

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

Stockli, Martin P. [SNS, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States); Leitner, M.; Keller, R. [SNS, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA, 94720 (United States); Moehs, D.P. [Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Welton, R. F. [SNS, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States)

2005-03-15

8

Navigation radar signal acquisition and measurement system  

Microsoft Academic Search

In the course of navigation, radar is a very important navigation aids. However, different types of radar always have different signal definition. In this paper, a kind of method on radar signal acquisition and measurement based on embedded system is proposed. The system, which could automatically detect some common radar signal parameter, is consist of CPLD, ARM micro processor, ADC

Shaowei Li; Xinqing Zhuang

2009-01-01

9

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

10

Interception of LPI radar signals  

Microsoft Academic Search

Most current radars are designed to transmit short duration pulses with relatively high peak power. These radars can be detected easily by the use of relatively modest EW intercept receivers. Three radar functions (search, anti-ship missile (ASM) seeker, and navigation) are examined to evaluate the effectiveness of potential low probability of intercept (LPI) techniques, such as waveform coding, antenna profile

Jim P. Lee

1991-01-01

11

Detection and Classification of Low Probability of Intercept Radar Signals Using Parallel Filter Arrays and Higher Order Statistics  

Microsoft Academic Search

Low probability of intercept (LPI) is that property of an emitter that because of its low power, wide bandwidth, frequency variability, or other design attributes, makes it difficult to be detected or identified by means of passive intercept devices such as radar warning, electronic support and electronic intelligence receivers. In order to detect LPI radar waveforms new signal processing techniques

Fernando L. Taboada

2002-01-01

12

Methods for Analysis of LPI Radar Signals  

Microsoft Academic Search

LPI (low probability of intercept) radars occupy wide frequency bands and have very low peak power so they are difficult to be detected by hostile intercept receivers. Hostile radiometric receivers are not able to intercept and measure the parameters of LPI signals which lie in wide frequency bands. In this study, four different methods for the analysis of LPI signals;

C. Tezel; Y. Ozkazanc

2006-01-01

13

Target Detection in Doppler Radar with PSK Signals  

E-print Network

that detection of targets with well-known structures of Radar Signal Processing in azimuth- distanceTarget Detection in Doppler Radar with PSK Signals Abstract -- The aim of this article is to test the effectiveness of the known structures of radar signal processing (RSP) that employ CFAR processors in order

Borissova, Daniela

14

Stepped-frequency radar signal processing  

NASA Astrophysics Data System (ADS)

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

Seyfried, Daniel; Schoebel, Joerg

2015-01-01

15

Detection and Parameter Estimiation of LPI Signals in Passive Radar  

Microsoft Academic Search

It is desired for multi-static passive radar to intercept target radar signals simultaneously during the process of location which utilize the difference time of arrival (DTOA). However, many LPI techniques are adopted by airborne radar in practice such as low side lobe method and narrow beam technique. As a result, receivers will not locate in the coverage of major lobe

Xiaoming Tang; Benqing Jiang; Caisheng Zhang; You He

2006-01-01

16

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

17

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

18

LPI Radar Sinyallerinin Ozimge Yaklasimi ile Siniflandirilmasi Classification of LPI Radar Signals via Eigenimage Approach  

Microsoft Academic Search

Low Probability of Intercept (LPI) Radar signals have the property of wide bandwidth, low peak power to make them difflcult to be detected by Electronic Support Measures (ESM) receivers. In this study, the detection performances of LPI Radar signals with Wigner-Ville Distributions are examined by treating each distribution as an image. The classification can be performed with an image processing

Engin Kocaadam; Yacup Ozkcazanc

2007-01-01

19

Signal processing techniques for stepped frequency ultra-wideband radar  

NASA Astrophysics Data System (ADS)

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

Nguyen, Lam

2014-05-01

20

Leakage signal analysis for position-adaptive UAV radar applications  

Microsoft Academic Search

The results of numerical electromagnetic simulation and analysis of a set of positive-adaptive UAV radar signals are presented. These signals are simulated via the modeling of materials that enclose \\

Atindra K. Mitra

2005-01-01

21

Signal to Noise Analysis of iRadar sensors  

SciTech Connect

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

Fritzke, A; Top, P

2009-09-10

22

Multitaper spectral analysis of atmospheric radar signals  

NASA Astrophysics Data System (ADS)

Multitaper spectral analysis using sinusoidal taper has been carried out on the backscattered signals received from the troposphere and lower stratosphere by the Gadanki Mesosphere-Stratosphere-Troposphere (MST) radar under various conditions of the signal-to-noise ratio. Comparison of study is made with sinusoidal taper of the order of three and single tapers of Hanning and rectangular tapers, to understand the relative merits of processing under the scheme. Power spectra plots show that echoes are better identified in the case of multitaper estimation, especially in the region of a weak signal-to-noise ratio. Further analysis is carried out to obtain three lower order moments from three estimation techniques. The results show that multitaper analysis gives a better signal-to-noise ratio or higher detectability. The spectral analysis through multitaper and single tapers is subjected to study of consistency in measurements. Results show that the multitaper estimate is better consistent in Doppler measurements compared to single taper estimates. Doppler width measurements with different approaches were studied and the results show that the estimation was better in the multitaper technique in terms of temporal resolution and estimation accuracy.

Anandan, V.; Pan, C.; Rajalakshmi, T.; Ramachandra Reddy, G.

2004-11-01

23

Signal processing for airborne bistatic radar  

E-print Network

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

Ong, Kian P

24

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

25

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

26

Sparse detection in the chirplet transform: application to FMCW radar signals  

E-print Network

. An illustration is provided on synthetic data. Index Terms--LPI radar, FMCW radar, chirplet transform, parameter estimation I. INTRODUCTION Low Probability of Intercept (LPI) Radars are a type of radar designed to hide) radars. This class of LPI radar signals may be modelled by r(t) = N n=1 An cos(2fn(t)t + n), (1) with fn

Paris-Sud XI, Université de

27

DETECTION AND SEGMENTATION OF FMCW RADAR SIGNALS BASED ON THE CHIRPLET TRANSFORM  

E-print Network

, and chirprate are estimated. An example is provided on a synthetic signal. Index Terms-- LPI radar, FMCW radar, chirplet trans- form, parameter estimation 1. INTRODUCTION Low Probability of Intercept (LPI) Radars and identify Frequency Modu- lation Continuous Wave (FMCW) radars. This class of LPI radar signals may

Paris-Sud XI, Université de

28

Noise radar interception using the principle of signal matched-phase  

Microsoft Academic Search

A noise radar transmits non-sinusoidal signals which are ultra-wideband and continuous. Theory and experiments show that the noise radar has excellent properties of low probability of interception (LPI). In electronic countermeasure (ECM), the LPI feature of the noise radar brings great challenges to the radar interception. This paper presents a method for noise radar signal detection, based on the principle

Long Keyu; Cheng Hao; Zeng Deguo; Li Yunhao; He Xiaodong; Tang Bing

2011-01-01

29

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; Jrg Heckenbach; Peter Willett; Shengli Zhou

2010-01-01

30

Doppler radar with multiphase modulation of transmitted and reflected signal  

NASA Technical Reports Server (NTRS)

A microwave radar signal is generated and split by a circulator. A phase shifter introduces a series of phase shifts into a first part of the split signal which is then transmitted by antenna. A like number of phase shifts is introduced by the phase shifter into the return signal from the target. The circulator delivers the phase shifted return signal and the leakage signal from the circulator to a mixer which generates an IF signal output at the Doppler frequency. The IF signal is amplified, filtered, counted per unit of time, and the result displayed to provide indications of target sense and range rate. An oscillator controls rate of phase shift in the transmitted and received radar signals and provides a time base for the counter. The phase shift magnitude increases may be continuous and linear or discrete functions of time.

Shores, Paul W. (inventor); Griffin, John W. (inventor); Kobayashi, Herbert S. (inventor)

1989-01-01

31

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

32

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

33

Analysis of Low Probability of Intercept (LPI) Radar Signals Using the Wigner Distribution  

Microsoft Academic Search

The parameters of Low Probability of Intercept (LPI) radar signals are hard to identity by using traditional periodogram signal processing techniques. Using the Wigner Distribution (WD), this thesis examines eight types of LPI radar signals. Signal to noise ratios of 0 dB and -6 dB are also investigated. The eight types LPI radar signals examined include Frequency Modulation Continuous Wave

Jen-Yu Gau

2002-01-01

34

Signal processing techniques for surveillance radar - An overview  

Microsoft Academic Search

The present paper is concerned with a survey of the signal processing techniques presently employed in modern air defense and surveillance radars and those techniques likely to be applied in the future. Attention is given to the requirements for enhancing performance in surveillance radar, current processing techniques, advanced techniques, low probability of intercept (LPI) and anti-ARM (anti-radiation missile), anti-stealth, digital

A. Farina; G. Galati

1985-01-01

35

Digital methods of the optimum processing of radar signals  

Microsoft Academic Search

In book questions of use\\/application of digital computers for optimum processing of radar signals are examined. Primary attention is given to the detection of signals from the targets, hidden by interferences, and to the determination of the target coordinates. Is described the work of the simplest diagrams of working\\/treatment, their operating principle, and also work of some nodes of digital

S. V. Samsonenko

1985-01-01

36

Detection and Estimation of LFMCW Radar Signals  

Microsoft Academic Search

The Wigner-Ville Hough transform (WVHT) is suboptimal in the detection and parameter estimation of linear frequency-modulated (LFM) continuous wave (LFMCW) low probability of intercept (LPI) radar waveforms because they are composed of concatenated LFM pulses. We formulate the detection and estimation problem to take into account the multiple pulses that are available in an observation interval at the intercept receiver.

Francis G. Geroleo; Maite Brandt-Pearce

2012-01-01

37

Waveform Diversity in Radar Signal Processing  

Microsoft Academic Search

This article shows that suitably transmitted and processed, radar waveforms based on Golay sequences provide new primitives for adaptive transmission that enable better detection and finer resolution, while managing computational complexity at the receiver. The ability to exploit space-time adaptive processing is limited by the computational power available at the receiver, and increased flexibility on transmission only exacerbates this problem

R. Calderbank; S. Howard; B. Moran

2009-01-01

38

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

39

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

40

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

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

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

41

Radar signals dismount tracking for urban operations  

NASA Astrophysics Data System (ADS)

It is critical in urban environments to not only track cars and tanks; but also individuals. Tracking dismounts, whereby an individual exits a car, can be done using conventional Electro-Optical (full color) or Infrared (thermal) cameras. However, EO/IR systems are subject to weather and line-of-sight conditions (i.e. person blocked by cloud) as well are degraded for long ranges. In this study, we pursue the use of radar images for dismount tracking. Radar dismount tracking will not entail the same robust features for person identification as EO systems; however, by being able to maintain track in all-weather conditions would afford friendly forces a location of all moving individuals. We show, using a feature-based tracker, that dismount detection, tracking, and potential intent, is possible. Radio Frequency (RF) tracking of dismounts is a relatively new concept because the data has not been available. By forming a data set based on the POSER TM program, and post-processing the data, we are interested in exploring the possibility of RF dismount tracking. In this paper, we (1) explore the generation of RF dismount data, (2) apply feature-based tracking algorithm to locate the moving target, and (3) assess the performance.

Blasch, Erik; Majumder, Uttam; Minardi, Michael

2006-05-01

42

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

E-print Network

For MIMO Radar Petre Stoica, Fellow, IEEE, Jian Li, Fellow, IEEE, and Yao Xie, Student Member, IEEE Abstract--A multiple-input multiple-output (MIMO) radar system, unlike a standard phased-array radar, can the cross-correlation of the signals reflected back to the radar by the targets of interest. In this paper

Xie, Yao

43

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

44

Bistatic radar without transmitted signal-covert altimetry concept  

Microsoft Academic Search

A technique for performing altimetric functions (and possibly very-low-resolution imaging radar) without the transmission of a signal is suggested. The system could benefit an invasive aerospace platform that needs to remain totally electronically silent. The concept uses naturally occurring galactic noise as the illumination signal. A rapid and low-cost processor is also suggested. The results developed are also useful for

J. E. Hershey; JAMES E SCHROEDER

1990-01-01

45

Signal processing at the Poker Flat MST radar  

NASA Technical Reports Server (NTRS)

Signal processing for Mesosphere-Stratosphere-Troposphere (MST) radar is carried out by a combination of hardware in high-speed, special-purpose devices and software in a general-purpose, minicomputer/array processor. A block diagram of the signal processing system is presented, and the steps in the processing pathway are described. The current processing capabilities are given, and a system offering greater coherent integration speed is advanced which hinges upon a high speed preprocessor.

Carter, D. A.

1983-01-01

46

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

47

Identification of LPI Radar signals by higher order spectra and neural network techniques  

Microsoft Academic Search

LPI Radars use continuous wave, wide bandwidth low power signals of the order of a few watts making its detection difficult. The important advantage of LPI radar is to go undetected, while maintaining a strong battlefield awareness. Common spectral analysis and conventional methods fail to detect emissions of LPI radars and even normal radars in noisy environments. This leads to

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

2008-01-01

48

Radar range data signal enhancement tracker  

NASA Technical Reports Server (NTRS)

The design, fabrication, and performance characteristics are described of two digital data signal enhancement filters which are capable of being inserted between the Space Shuttle Navigation Sensor outputs and the guidance computer. Commonality of interfaces has been stressed so that the filters may be evaluated through operation with simulated sensors or with actual prototype sensor hardware. The filters will provide both a smoothed range and range rate output. Different conceptual approaches are utilized for each filter. The first filter is based on a combination low pass nonrecursive filter and a cascaded simple average smoother for range and range rate, respectively. Filter number two is a tracking filter which is capable of following transient data of the type encountered during burn periods. A test simulator was also designed which generates typical shuttle navigation sensor data.

1975-01-01

49

Signal based motion compensation for synthetic aperture radar  

SciTech Connect

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

John Kirk

1999-06-07

50

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

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

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

51

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

E-print Network

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

Oppenheim, Meers

52

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

53

Radar sensor using low probability of interception SS-FH signals  

Microsoft Academic Search

One of the best known weakness of radar sensors in defense and security applications is the necessity to radiate a signal, which can be detected by the target, so being possible (easy in fact) that the target is alerted about the presence of a radar before the radar is alerted about the presence of a target. In this context, Low

M. Burgos-Garcia; J. Sanmartin-Jara; F. Perez-Martinez; J. A. Retamosa

2000-01-01

54

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

Microsoft Academic Search

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

Antonio F. Lime Jr.

2002-01-01

55

Comparison of Target Detection Schemes in Doppler Radar with PSK Signals  

E-print Network

Continuous Wave (FMCW) radar with Low probability of Intercept (LPI). In the paper are studied and comparedComparison of Target Detection Schemes in Doppler Radar with PSK Signals Chr. Kabakchiev #1 , I CA, OS, SO, GO CFAR processors. Keywords ­ Dopller radar, Target detection, CFAR processors I

Borissova, Daniela

56

SUBMITTED TO THE IEEE TRANSACTIONS ON SIGNAL PROCESSING 1 Spatial Diversity in Radars -Models and  

E-print Network

SUBMITTED TO THE IEEE TRANSACTIONS ON SIGNAL PROCESSING 1 Spatial Diversity in Radars - Models the coherent processing gain, while statistical MIMO radar capitalizes on the diversity of target scattering diversity of target scatterers opening the way to a variety of new techniques that can improve radar

Blum, Rick

57

A Kind of Signal Processing Method for the Polarization Phased Array Radar  

Microsoft Academic Search

This paper discusses a kind of polarization phased array radar system and its signal processing method. The polarization signal processing technology is introduced to improve the detection performance and anti-jamming ability of the radars. In order to achieve the performance of low probability of intercept (LPI) for the transmitted signal, the linear frequency modulation (LFM) is adopted inside each pulse

Song Li-zhong; Qiao Xiao-lin; Fu Shi-feng; Wu Qun

2009-01-01

58

A new method for direct signal recover in non-cooperative bistatic radar  

Microsoft Academic Search

The direct signal which includes noise and multipath clutter greatly declines the performance of the non-cooperation bistatic radar system. To mitigate this problem, a new method based on three-sensor array for direct signal recover in non- cooperation bistatic radar is proposed. The expression of recovering direct signal from white noise and multipath clutter is analyzed in detail. Statistical performances of

Hui Li; You He; Hong-qing Zhou; Jun Peng

2011-01-01

59

Experimental Investigation of a Direct Chaotic Signal Radar with Colpitts Oscillator  

Microsoft Academic Search

Generated by an ordinary Colpitts oscillator, chaotic waveforms with bandwidth larger than several GHz can be readily obtained. A prototype of chaotic signal radar with Colpitts oscillator is set up to experimentally investigate the performance of chaotic signal in radar system. The correlation traces between the transmitted and reference signals are presented, whose spike point reveals the experimental transmission distance.

T. Jiang; J. Long; Z. Wang; S. Qiao; W. Cui; W. Ma; J. Huangfu; L. Ran

2010-01-01

60

Advanced Signal Analysis for Forensic Applications of Ground Penetrating Radar  

SciTech Connect

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

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

2004-06-01

61

Leakage signal analysis for position-adaptive UAV radar applications  

NASA Astrophysics Data System (ADS)

The results of numerical electromagnetic simulation and analysis of a set of positive-adaptive UAV radar signals are presented. These signals are simulated via the modeling of materials that enclose "building-type" structures with a series of connected dielectric materials. For example, windows, walls, and doors are each modeled separately by a combination of suitable material properties. Signals from objects that are embedded within these "building-type" structures are also simulated via the development and application of appropriate geometrical and materials models. Analysis of the resulting simulated "leakage signals" that penetrate the surfaces of these "building-type" structures and are backscattered from embedded objects within the indoor environment back to the simulated outdoor environment are presented. The results of a signal analysis are presented in two categories. The first set of results illustrates signal trends that can be exploited by "position-adaptive" mini-UAV's to isolate effective "leakage points" in "building-type" structures. The second set of results illustrate signal trends from embedded objects after a particular "position-adaptive" mini-UAV has converged to a "leakage point."

Mitra, Atindra K.

2005-05-01

62

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

63

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

NASA Astrophysics Data System (ADS)

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

Fairchild, Dustin P.; Narayanan, Ram M.

2014-06-01

64

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

65

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

66

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

67

Graphical derivations of radar, sonar, and communication signals  

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

68

Discrimination against interfering signals at the Poker Flat MST radar  

NASA Technical Reports Server (NTRS)

Several on line and off line data processing techniques are used to remove interfering signals due to ground clutter, aircraft, instrumental effects, and external transmissions from the desired atmospheric echoes of Mesosphere Stratosphere, Troposphere (MST) radar. The on line, real time techniques are necessarily simple in order to minimize processing delays. This algorithm examines the individual Doppler spectra which are computed every two to four seconds (for oblique antenna beams). The total spectral power in each individual spectrum is computed by summing all the spectral points. If this integrated power increases from one spectrum to the next by a factor greater than a preselected threshold, then that spectrum is not added to the spectral sum. Succeeding spectra are compared to the last acceptable spectrum. Only a certain maximum number of spectra are allowed to be rejected in succession.

Carter, D. A.

1983-01-01

69

A novel method for LPI radar signal sorting in multipath channel  

Microsoft Academic Search

Signal sorting of low probability of interception (LPI) radar signals is extremely important in electronic support measurement (ESM) systems. Usually, there are multipath interferences in the intercepted signals, which result in the decrease of signal sorting performance of conventional methods. In this paper, we present a local ambiguity function (AF)-based signal sorting method for multipath fading environments. The singular vectors

Li Jiang; Lin Li; Guo-Qing Zhao

2012-01-01

70

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

71

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

72

Augmentation of the speed and quality of a bipolar integrated circuit based on small signal elements with emitter coupled logic  

Microsoft Academic Search

Analytic expressions are derived for transient processes in the base and collector regions of a current switch, and are used to examine a bipolar integrated circuit constructed on the basis of small signal elements with emitter coupled logic. Pulsed noise originating in the logic networks of the small signal elements through the capacitance couplings is analyzed. The feasibility of using

V. G. Nemudrov; Iu. K. Kushner; A. N. Khabarov

1975-01-01

73

Waveform Design and Signal Processing Aspects for Fusion of Wireless Communications and Radar Sensing  

Microsoft Academic Search

Since traditional radar signals are Bunintelligent,( regarding the amount of information they convey on the band- width they occupy, a joint radar and wireless communication system would constitute a unique platform for future intelli- gent transportation networks effecting the essential tasks of environmental sensing and the allocation of ad-hoc commu- nication links, in terms of both spectrum efficiency and cost-

Christian Sturm; Werner Wiesbeck

2011-01-01

74

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

E-print Network

Multi-PRI Signal Processing for the Terminal Doppler Weather Radar. Part I: Clutter Filtering JOHN and processing algorithm being developed to aggressively combat range­velocity ambiguity in weather radars-elevation scans and yield low biases of velocity estimates so that accurate velocity dealiasing is possible

Cho, John Y. N.

75

Autonomous non-linear classification of LPI radar signal modulations .  

E-print Network

??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 (more)

Gulum, Taylan O.

2007-01-01

76

MIMO RADAR DIVERSITY WITH NEYMAN-PEARSON SIGNAL DETECTION IN NON-GAUSSIAN CIRCUMSTANCE WITH NON-ORTHOGONAL WAVEFORMS  

E-print Network

MIMO RADAR DIVERSITY WITH NEYMAN-PEARSON SIGNAL DETECTION IN NON-GAUSSIAN CIRCUMSTANCE WITH NON-Gaussian clutter-plus-noise. It is found that the diversity gain for the MIMO radar system is dependent, signal space. 1. INTRODUCTION Diversity gain is one of the most significant advantage of the MIMO radar

Blum, Rick

77

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

78

On the Doppler Frequency Shifts of Radar Signals Backscattered from the Sea Surface  

NASA Astrophysics Data System (ADS)

We study the frequency spectra of the radar signals scattered from the wind waves on the sea surface in the full-scale experiment. Two types of the radar Doppler shifts of the spectrum maximum, namely, the averaged shift of the instantaneous spectrum of the scattered signal and the shift of the maximum of the signal time-averaged spectrum as functions of the incidence angle and the wind velocity and direction are analyzed for different sounding-wave polarizations. Significant difference between the average shift of the instantaneous spectrum and the shift of the average-spectrum maximum is demonstrated. This difference is attributed to the radar-signal modulation effect in the field of long surface waves. The obtained results are very important for correct retrieval of the velocities of the surface currents using the data of the satellite-borne measurements of the radar Doppler shifts.

Ermakov, S. A.; Kapustin, I. A.; Kudryavtsev, V. N.; Sergievskaya, I. A.; Shomina, O. V.; Chapron, B.; Yurovskiy, Yu. Yu.

2014-09-01

79

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

Microsoft Academic Search

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

Atindra K. Mitra

2006-01-01

80

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

81

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

Microsoft Academic Search

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

Yury Grishin; Dariusz Janczak

2008-01-01

82

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

NASA Astrophysics Data System (ADS)

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

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

83

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

84

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

85

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; lvaro Blanco del Campo; Javier Gismero Menoyo; Alberto Asensio Lpez

2008-01-01

86

Multiple scattering of HF skywave radar signals : Physics, interpretation and exploitation  

Microsoft Academic Search

HF radar signals rely on the ionosphere to achieve over-the-horizon surveillance, but this is obtained at the expense of subjecting the signals to a diverse range of scattering and modulation phenomena. Many of these effects are associated with multiple scattering, both in the ionosphere and near the earthpsilas surface. This paper reviews a variety of multiple scattering phenomena and shows

Stuart Anderson

2008-01-01

87

Time-frequency quasi-matched intelligence receiver to LPI radar signal  

Microsoft Academic Search

An intelligence receiver quasi-matched to the received LPI radar signals in time and frequency domain is presented. The architecture and prototype using FPGA and DSP are shown. The presented receiver works especially well when the received signals are complex and time-varying.

Deguo Zeng; Hao Cheng; Keyu Long; Xiaodong Zeng; Haiyan Gu; Xiaodong He; Bin Tang

2011-01-01

88

Characterization of a fiber-optic direct modulation analog link with chirp radar signals  

Microsoft Academic Search

This paper describes the experimental investigations carried out to evaluate the behaviour of a fiber-optic direct modulation analog link as a substitute of traditional transmission means, like coaxial cables or waveguides, for X-band chirp modulated radar signals. First of all, the link has been completely characterized, and the spurious frequency modulation has been measured in presence of pulsed signals. Afterwards,

Rossano Pardini; Umberto Bruno; Roberto Izzo

2009-01-01

89

Onboard passive return signal simulator for space-borne radar altimeters  

Microsoft Academic Search

It is important for a spaceborne radar altimeter to have the ability for onboard waveform calibration. However it is difficult to simulate the return wave at microwave frequency that contains a complete waveform. In this paper, we present a novel design for a passive return signal simulator (RSS) which has the ability to provide a complete waveform using a signal

Ji Wu; Liwei Wang; Zhenfan Zheng; Jingshan Jiang

1998-01-01

90

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

NASA Technical Reports Server (NTRS)

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

Weissman, David E.; Staton, Leo D.

1991-01-01

91

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)

2011-02-01

92

On the signal design for multifunction\\/multi-parameter radar  

Microsoft Academic Search

The requirements and the possible solutions for waveforms suited to multifunction phased array radar (MPAR) are described. A reasonable cost of the basic building block of the MPAR, i.e. for the Transmit-receive module (TRM), can only be obtained by lowering the peak power to the order of one watt by pulse-compression. Therefore, MPAR systems call for \\

Gaspare Galati; Gabriele Pavan

2011-01-01

93

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

94

A new wide-band noise radar signal and its compression  

Microsoft Academic Search

In this paper, we propose a wide-band noise radar signal model which is composed of a train of pulsed noise signals with their carrier frequencies increased\\/decreased linearly, and we call it as stepped-frequency noise signals (SFNSs). At the same time we also propose the corresponding compressing algorithm based on the compressed sensing theory. The random property of the transmitted waveform

Xiao Dong; Yunhua Zhang; Xiang Gu

2011-01-01

95

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

USGS Publications Warehouse

It is found that the Shuttle Imaging Radar A (SIR-A) signal penetration and subsurface backscatter within the upper meter or so of the sediment blanket in the Eastern Sahara of southern Egypt and northern Sudan are enhanced both by radar sensor parameters and by the physical and chemical characteristics of eolian and alluvial materials. The near-surface stratigraphy, the electrical properties of materials, and the types of radar interfaces found to be responsible for different classes of SIR-A tonal response are summarized. The dominant factors related to efficient microwave signal penetration into the sediment blanket include 1) favorable distribution of particle sizes, 2) extremely low moisture content and 3) reduced geometric scattering at the SIR-A frequency (1. 3 GHz). The depth of signal penetration that results in a recorded backscatter, called radar imaging depth, was documented in the field to be a maximum of 1. 5 m, or 0. 25 times the calculated skin depth, for the sediment blanket. The radar imaging depth is estimated to be between 2 and 3 m for active sand dune materials.

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

1986-01-01

96

Quantitative estimation of Tropical Rainfall Mapping Mission precipitation radar signals from ground-based polarimetric radar observations  

NASA Astrophysics Data System (ADS)

The Tropical Rainfall Mapping Mission (TRMM) is the first mission dedicated to measuring rainfall from space using radar. The precipitation radar (PR) is one of several instruments aboard the TRMM satellite that is operating in a nearly circular orbit with nominal altitude of 350 km, inclination of 35, and period of 91.5 min. The PR is a single-frequency Ku-band instrument that is designed to yield information about the vertical storm structure so as to gain insight into the intensity and distribution of rainfall. Attenuation effects on PR measurements, however, can be significant and as high as 10-15 dB. This can seriously impair the accuracy of rain rate retrieval algorithms derived from PR signal returns. Quantitative estimation of PR attenuation is made along the PR beam via ground-based polarimetric observations to validate attenuation correction procedures used by the PR. The reflectivity (Zh) at horizontal polarization and specific differential phase (Kdp) are found along the beam from S-band ground radar measurements, and theoretical modeling is used to determine the expected specific attenuation (k) along the space-Earth path at Ku-band frequency from these measurements. A theoretical k-Kdp relationship is determined for rain when Kdp ? 0.5/km, and a power law relationship, k = a Zhb, is determined for light rain and other types of hydrometers encountered along the path. After alignment and resolution volume matching is made between ground and PR measurements, the two-way path-integrated attenuation (PIA) is calculated along the PR propagation path by integrating the specific attenuation along the path. The PR reflectivity derived after removing the PIA is also compared against ground radar observations.

Bolen, Steven M.; Chandrasekar, V.

2003-06-01

97

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

E-print Network

Multi-PRI Signal Processing for the Terminal Doppler Weather Radar. Part II: Range­Velocity developed to combat range­velocity (RV) ambiguity for the Terminal Doppler Weather Radar (TDWR). In Part I and velocity dealiasing using multi-PRI signal transmission and processing are presented. The effectiveness

Cho, John Y. N.

98

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

NASA Astrophysics Data System (ADS)

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

Mitra, Atindra K.

2006-05-01

99

Research of Amplitude - Time Characteristic of Television Signal Reflected From a Meteoric Trail in Spased Radar System  

Microsoft Academic Search

In this paper the technique of processing the television signal reflected from a meteoric trail for research of parameters of amplitude-time characteristics of signals in the spased radar system is considered.

A. N. Oleynikov; D. M. Sosnovchik

2006-01-01

100

Coherent Laser Radar Conference Signal Processing Methods and Poly-Pulse Waveforms  

E-print Network

15th Coherent Laser Radar Conference Signal Processing Methods and Poly-Pulse Waveforms for Laser (IF) estimators is compared through simulation, taking into account Continuous Wave (CW) and pulse Vibrometry in Pulsed Mode J. Totems1 , V. Jolivet1 , J.-P. Ovarlez1 , N. Martin2 1 ONERA, The French

Paris-Sud XI, Université de

101

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

E-print Network

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

Mark A. Rubin; Sumanth Kaushik

2007-04-05

102

Assessment of Radar Signal Attenuation Caused by the Melting Hydrometeor Layer  

Microsoft Academic Search

Attenuation of radar signals by melting hydrometeors is studied using modeling approaches and comparisons of simulated and observed results. In spite that the melting layer in precipitating systems is usually relatively thin ( ~ 500 m), this attenuation can be substantial at X-band frequencies for low elevation angles and at millimeter-wavelength frequencies that are used by the U.S. Department of

Sergey Y. Matrosov

2008-01-01

103

Sparse signal processing on estimation grid with constant information distance applied in radar  

NASA Astrophysics Data System (ADS)

Radar obtains its parameters on a grid whose design supports resolution of underlying radar processing. Existing radar exploits a regular grid although the resolution changes with stronger echoes at shorter ranges. We compute the radar resolution from the intrinsic geometrical structure of data models that is characterized in terms of the Fisher information metric. Based on the information-based approach, we design an estimation grid whose cells have a constant Fisher information distance. In addition, we explore how this information-based grid can suit radar processing in practice and propose information-based processing on such an irregular estimation grid by applying the sparse signal processing from compressive sensing. Accordingly, the grid was adjusted to the sensing incoherence needed in sparse signal processing by setting a lower bound for the cell size. Our approach enables an adaptive estimation grid that can be adjusted with respect to the available resolution, the desired sensing incoherence, available computational power, and required operational priorities. The information-based design and processing are illustrated in a one-dimensional case of range estimation.

de Jong, Edwin; Pribi?, Radmila

2014-12-01

104

An overview of data acquisition, signal coding and data analysis techniques for MST radars  

NASA Technical Reports Server (NTRS)

An overview is given of the data acquisition, signal processing, and data analysis techniques that are currently in use with high power MST/ST (mesosphere stratosphere troposphere/stratosphere troposphere) radars. This review supplements the works of Rastogi (1983) and Farley (1984) presented at previous MAP workshops. A general description is given of data acquisition and signal processing operations and they are characterized on the basis of their disparate time scales. Then signal coding, a brief description of frequently used codes, and their limitations are discussed, and finally, several aspects of statistical data processing such as signal statistics, power spectrum and autocovariance analysis, outlier removal techniques are discussed.

Rastogi, P. K.

1986-01-01

105

Analysis of wavelet-based denoising techniques as applied to a radar signal pulse  

NASA Astrophysics Data System (ADS)

The purpose of the research is to study the effects of three wavelet-based denoising techniques on the structure of a radar signal pulse. The radar signal pulse is 50 microsecond(s) ec in duration with 2.0 MHz of Linear Frequency Modulation on Pulse. The Signal-to-Noise Ratio of the signal is fixed at 0.7. The comparison is accomplished in the time-domain and the FFT domain. In addition, the output from a FM Demodulator is examined. The comparisons are performed based upon MSE calculations and a visual inspection of the resulting signals. A comparison between the results outlined above and an ideal bandpass filter is also performed. A final comparison is discussed which compares the wavelet- based results outlined above and the results obtained from a bandpass filter that are offset in center frequency. The wavelet-based techniques can be shown to provide an advantage in visually detecting the radar signal pulse in low SNR environments over the results obtained from a bandpass filter approach in which the ideal filter characteristics are not known. All work is accomplished in MATLABTM.

Steinbrunner, Lori A.; Scarpino, Frank F.

1999-09-01

106

Signal and noise level estimation for narrow spectral width returns observed by the Indian MST radar  

NASA Astrophysics Data System (ADS)

Use is made of five sets of multibeam observations of the lower atmosphere made by the Indian mesosphere-stratosphere-troposphere (MST) radar. Two aspects of signal processing which can lead to serious underestimates of the signal-to-noise ratio are considered. First, a comparison is made of the effects of different data weighting windows applied to the inphase and quadrature components of the radar return samples prior to Fourier transformation. The relatively high degree of spectral leakage associated with the rectangular and Hamming windows can give rise to overestimates of the noise levels by up to 28 dB for the strongest signals. Use of the Hanning window is found to be the most appropriate for these particular data. Second, a technique for removing systematic dc biases from the data in the time domain is compared with the more well-known practice of correction in the frequency domain. The latter technique, which is often used to remove the effects of ground clutter, is shown to be particularly inappropriate for the characteristically narrow spectral width signals observed by the Indian MST radar. For cases of near-zero Doppler shift it can remove up to 30 dB of signal information. The consequences of noise and signal level discrepancies for studies of refractivity structures are discussed. It is shown that neither problem has a significant effect on Doppler shift or spectral width estimates.

Hooper, D. A.

1999-07-01

107

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

108

A Novel Radar Sensor for the Non-Contact Detection of Speech Signals  

PubMed Central

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

109

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

110

Effect of signal path distortions on the decoding performance in a pulse compression radar system  

NASA Astrophysics Data System (ADS)

Computer simulation studies have been conducted on the range side lobe performance of a pulse compression radar system which uses a complementary biphase-coded signal transmission. Such a coding scheme is widely used in mesosphere-stratosphere-troposphere (MST) radars expecting to achieve ideally zero range side lobes to ensure unambiguous detection of signals. However, system parameters, like overall system bandwidth, delay distortion, limiting, amplitude and phase droop within the pulse, can lead to spillover of a target return into adjacent range bins by raising the range side lobe level. The results of the study indicate that a goal of 20-dB range side lobe level can be achieved with matched filter bandwidth and reasonable levels of amplitude and phase distortions in the signal path.

Patro, Y. G. K.; Suresh Nair, K. R.; Balamuralidhar, P.

1990-10-01

111

1886 IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 49, NO. 9, SEPTEMBER 2001 Time-Averaged Subspace Methods for Radar Clutter  

E-print Network

. The application context is the retrieval of texture infor- mation from high resolution and low grazing angle radar at low grazing angle. Under this circumstance, the observed signal can be modeled in discrete Methods for Radar Clutter Texture Retrieval Fulvio Gini, Senior Member, IEEE, Georgios B. Giannakis

Giannakis, Georgios

112

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

113

Linear photonic technique for fixed and time varying RF phase shifts of radar signals.  

PubMed

A simple linear photonic technique is proposed to achieve fixed or time varying radio-frequency (RF) phase shifts which can be used in applications such as radar signal manipulation. The technique is based on fixing or tuning the wavelength of an RF modulated optical signal within the reflection band of a fiber Bragg grating (FBG) filter with a step group delay profile. The scheme is verified in a realistic simulation to achieve a Doppler shift in a pulsed CW signal return. PMID:23038350

Attygalle, Manik; Stepanov, Dmitrii

2012-07-30

114

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

115

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

NASA Astrophysics Data System (ADS)

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 tone-burst wave propagation signals are generated and collected by the embedded PWAS. Then, with signal processing, the frequency contents of the signals and the time of flight of individual frequencies are determined. This paper starts with an introduction of embedded ultrasonic structural radar algorithm. Then we will describe the signal processing methods used to extract the time of flight of the wave packages. The signal processing methods being used include the wavelet denoising, the cross correlation, and Hilbert transform. Though hardware device can provide averaging function to eliminate the noise coming from the signal collection process, wavelet denoising is included to ensure better signal quality for the application in real severe environment. For better recognition of time of flight, cross correlation method is used. Hilbert transform is applied to the signals after cross correlation in order to extract the envelope of the signals. Signal processing and EUSR are both implemented by developing a graphical user-friendly interface program in LabView. We conclude with a description of our vision for applying EUSR signal analysis to structural health monitoring and embedded nondestructive evaluation. To this end, we envisage an automatic damage detection application utilizing embedded PWAS, EUSR, and advanced signal processing.

Yu, Lingyu; Bao, Jingjing; Giurgiutiu, Victor

2004-07-01

116

A study of signal statistics of VHF radar echoes from clear air  

NASA Astrophysics Data System (ADS)

Signal statistics of VHF radar returns from vertical pointing observations of the clear air are investigated. In particular, the signal signature, its Doppler spectrum and statistical distribution are examined. It is found that the most important factors that characterize the statistics of the signals are the width of the spectrum and the Nakagami m-coefficient for the intensity distribution. Using these factors as criteria, two types of signals are found. One corresponds to volume scattering arising from turbulence or multiple thin laminae or sheets. The other corresponds to return from a single sheet. Examples of the different scattering/reflection processes will be shown. Numerical modelling is used to simulate the scattering/reflection processes. From the simulation, it is demonstrated that echo signals from some range gates are consistent with the picture of reflection from a single, diffuse sheet, causing focusing and defocusing of the signals.

Sheen, D. R.; Liu, C. H.; Rottger, J.

1985-07-01

117

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

118

A signal processing view of strip-mapping synthetic aperture radar  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

119

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

120

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

121

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

122

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

123

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

124

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

125

Thermally enhanced signal strength and SNR improvement of photoacoustic radar module.  

PubMed

A thermally enhanced method for improving photoacoustic imaging depth and signal-to-noise (SNR) ratio is presented in this paper. Experimental results showed that the maximum imaging depth increased by 20% through raising the temperature of absorbing biotissues (ex-vivo beef muscle) uniformly from 37 to 43C, and the SNR was increased by 8%. The parameters making up the Gruneisen constant were investigated experimentally and theoretically. The studies showed that the Gruneisen constant of biotissues increases with temperature, and the results were found to be consistent with the photoacousitc radar theory. PMID:25136501

Wang, Wei; Mandelis, Andreas

2014-08-01

126

Thermally enhanced signal strength and SNR improvement of photoacoustic radar module  

PubMed Central

A thermally enhanced method for improving photoacoustic imaging depth and signal-to-noise (SNR) ratio is presented in this paper. Experimental results showed that the maximum imaging depth increased by 20% through raising the temperature of absorbing biotissues (ex-vivo beef muscle) uniformly from 37 to 43C, and the SNR was increased by 8%. The parameters making up the Gruneisen constant were investigated experimentally and theoretically. The studies showed that the Gruneisen constant of biotissues increases with temperature, and the results were found to be consistent with the photoacousitc radar theory. PMID:25136501

Wang, Wei; Mandelis, Andreas

2014-01-01

127

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

E-print Network

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

Mark A. Rubin; Sumanth Kaushik

2009-07-30

128

A Novel Method for Recognition of Modulation Code of LPI Radar Signals  

Microsoft Academic Search

The Low Probability of Intercept (LPI) capability of the radar defeats conventional RWR\\/ESM systems. The important advantage of LPI radar is to go undetected, while maintaining a strong battlefield awareness. Common Spectral analysis and conventional methods fail to detect emissions of LPI Radars and even normal radars in noisy environments. This leads to use Higher Order Spectral Analysis (HOSA) techniques

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

129

The principle of synthesizing HRRP based on a new OFDM phase-coded stepped-frequency radar signal  

Microsoft Academic Search

Orthogonal Frequency-Division Multiplexing (OFDM) phase-coded pulse is a wideband signal, of which the range resolution is inversely proportional to the bandwidth. However, it is a challenge to synthesize large bandwidth for OFDM phase-coded pulse since wide instantaneous bandwidth and high sampling rate requirements. To solve this problem, this paper proposes a new radar signal called OFDM phase-coded stepped-frequency (OFDM-PCSF) signal,

Kai Huo; Bin Deng; Yongxiang Liu; Weidong Jiang; Junjie Mao

2010-01-01

130

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

131

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

132

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

133

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

134

Nanoelectrospray Emitter Arrays Providing Inter-Emitter Electric Field Uniformity  

PubMed Central

Arrays of electrospray ionization (ESI) emitters have been reported previously as a means of enhancing ionization efficiency or signal intensity. A key challenge when working with multiple, closely spaced ESI emitters is overcoming the deleterious effects caused by electrical interference among neighboring emitters. Individual emitters can experience different electric fields depending on their relative position in the array, such that it becomes difficult to operate all of the emitters optimally for a given applied potential. In this work, we have developed multi-nanoESI emitters arranged with a circular pattern, which enable the constituent emitters to experience a uniform electric field. The performance of the circular emitter array was compared to a single emitter and to a previously developed linear emitter array, which verified that improved electric field uniformity was achieved with the circular arrangement. The circular arrays were also interfaced with a mass spectrometer via a matching multi-capillary inlet, and the results were compared with those obtained using a single emitter. By minimizing inter-emitter electric field inhomogeneities, much larger arrays having closer emitter spacing should be feasible. PMID:18553942

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

2008-01-01

135

Wideband radar imaging for space debris based on direct IF sampling signals  

NASA Astrophysics Data System (ADS)

This paper investigates an imaging method for space debris by wideband radar. Because of the spinning of the space debris, the correlation of the adjacent high range resolution profile (HRRP) is undermined and the motion compensation method for dechirped echoes is invalid. Therefore, a wideband imaging method of space debris based on intermediate frequency sampling (DIFS) signals is proposed in this paper. The IF sampling technique has the advantage in maintaining the coherence of echo pulse, which eliminates the negative influence of the spin. Firstly, the accurate translational motion parameters of the target are estimated from the radar observations by using of polynomial fitting method. Then the translational motion compensation is carried out in frequency domain based on the target motion track. Finally, the improved back projection transform (BPT) method is used for image reconstruction, which transforms the echo from range-time domain to the scattering point distribution plane by coherent integral. A well-focused and high resolution image of the space debris without side lobe peaks can be obtained in the end. The simulation results indicate the validity of the proposed method in this paper.

Liu, Yang; Chen, Zengping; Li, Na; Xu, Shiyou

2014-10-01

136

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

137

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

E-print Network

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

138

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

E-print Network

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

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

139

Classification of polyphase and polytime LPI radar signals with eigenimage methods  

Microsoft Academic Search

LPI (Low Probability of Intercept) radars are based on an advanced architecture which makes use of coded pulses. As a synergetic byproduct, a low probability of intercept is also achieved due to the low power levels of LPI radars. In this study, some classification based methods for the uncooperative detection of LPI radar pulses are proposed. We specialized on polyphase

Engin KOCAADAM; Yakup ZKAZAN

2010-01-01

140

Emitter Geolocation with Multiple UAVs  

Microsoft Academic Search

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

Nickens Okello

2006-01-01

141

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

NASA Technical Reports Server (NTRS)

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

Nicholson, Shaun R.

1994-01-01

142

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

143

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

144

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

NASA Technical Reports Server (NTRS)

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

Bolen, Steve; Chandrasekar, V.

2002-01-01

145

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

NASA Technical Reports Server (NTRS)

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 time display of the height profiles of the two coherently integrated components; (4) real time calculation of the 1 minute averages of the power and autocovariance function up to 6 lags; (5) output of these data to floppy disk once every 2 minutes; (6) display of the 1 minute power profiles while the data are stored to the disk; (7) visual prompting for the operator to change disks when required at the end of each hour of data; and (8) continuous audible indication of the status of the interrupt service routine. Accomplishments were enabled by two developments: the use of a new correlation algorithm and the use of the FORTH language to manage the various low level and high level procedures involved.

Bowhill, S. A.

1983-01-01

146

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

147

Development of a ground signal processor for digital synthetic array radar data  

NASA Technical Reports Server (NTRS)

A modified APQ-102 sidelooking array radar (SLAR) in a B-57 aircraft test bed is used, with other optical and infrared sensors, in remote sensing of Earth surface features for various users at NASA Johnson Space Center. The video from the radar is normally recorded on photographic film and subsequently processed photographically into high resolution radar images. Using a high speed sampling (digitizing) system, the two receiver channels of cross-and co-polarized video are recorded on wideband magnetic tape along with radar and platform parameters. These data are subsequently reformatted and processed into digital synthetic aperture radar images with the image data available on magnetic tape for subsequent analysis by investigators. The system design and results obtained are described.

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

1981-01-01

148

Radar Ionospheric Impact Mitigation  

Microsoft Academic Search

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

G. Bishop; D. Decker; C. Baker

2006-01-01

149

Extended Emitter Target Tracking Using GM-PHD Filter.  

PubMed

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

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

2014-01-01

150

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

151

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

152

Worldwide uncertainty assessments of ladar and radar signal-to-noise ratio performance for diverse low altitude atmospheric environments  

NASA Astrophysics Data System (ADS)

In this study of atmospheric effects on laser ranging and detection (ladar) and radar systems, the parameter space is explored using the Air Force Institute of Technology Center for Directed Energy's (AFIT/CDE) High Energy Laser End-to-End Operational Simulation (HELEEOS) parametric one-on-one engagement level model. The expected performance of ladar systems is assessed at a representative wavelength of 1.557 m at a number of widely dispersed land and maritime locations worldwide. Radar system performance is assessed at 95 GHz and 250 GHz. Scenarios evaluated include both down looking oblique and vertical engagement geometries over ranges up to 3000 meters in which clear air aerosols and thin layers of fog, locally heavy rain, and low stratus cloud types are expected to occur. Seasonal and boundary layer variations are considered to determine optimum employment techniques to exploit or defeat the environmental conditions. Each atmospheric particulate/obscurant/hydrometeor is evaluated based on its wavelength-dependent forward and off-axis scattering characteristics and absorption effects on system interrogation. Results are presented in the form of worldwide plots of notional signal to noise ratio. The ladar and 95 GHz system types exhibit similar SNR performance for forward oblique clear air operation. 1.557 m ladar performs well for vertical geometries in the presence of ground fog, but has no near-horizontal performance under such meteorological conditions. It also has no performance if low altitude stratus is present. 95 GHz performs well for both the fog and stratus layer cases, for both vertical and forward oblique geometries. The 250 GHz radar system is heavily impacted by water vapor absorption in all scenarios studied; however it is not as strongly affected by clouds and fog as the 1.557 m ladar. Locally heavy rain will severely limit ladar system performance at these wavelengths. However, under heavy rain conditions ladar outperforms both radar systems.

Fiorino, Steven T.; Bartell, Richard J.; Krizo, Matthew J.; Caylor, Gregory; Moore, Kenneth P.; Harris, Thomas R.; Cusumano, Salvatore J.

2010-06-01

153

Synthetic aperture radar interferometry  

Microsoft Academic Search

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

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

2000-01-01

154

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

Microsoft Academic Search

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

Werner Alpers; Klaus Hasselmann

1982-01-01

155

Comparison of target detection schemes in Doppler radar with PSK signals  

Microsoft Academic Search

The aim of this article is to test the effectiveness of the known CFAR processors in order to detect moving targets in the frequency domain of real records. The purpose is to be chosen optimal CFAR detector for moving target detection. The data are obtained by portable, surveillance, Frequency Modulated Continuous Wave (FMCW) radar with Low probability of Intercept (LPI).

C. Kabakchiev; I. Garvanov; P. Daskalov; P. Donkov; D. Kabakchieva

2010-01-01

156

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

E-print Network

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

Préaux, Jean-Philippe

157

Enhanced emitter-coupled logic (EECL)  

Microsoft Academic Search

Design enhancements to emitter coupled logic are proposed. In the enhanced emitter-coupled logic (EECL) circuits (a) no reference voltage (V bb) is required, (b) complex logic functions containing a mix of complemented and uncomplemented input signals may be realized in a single gate stage, (c) the diode clamps commonly used when collector-dotting ECL circuits are not required, and (d) signal

J. Price

1990-01-01

158

Ground-penetrating radar methods  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

159

Complementary code and digital filtering for detection of weak VHF radar signals from the mesoscale. [SOUSY-VHF radar, Harz Mountains, Germany  

NASA Technical Reports Server (NTRS)

The SOUSY-VHF-Radar operates at a frequency of 53.5 MHz in a valley in the Harz mountains, Germany, 90 km from Hanover. The radar controller, which is programmed by a 16-bit computer holds 1024 program steps in core and controls, via 8 channels, the whole radar system: in particular the master oscillator, the transmitter, the transmit-receive-switch, the receiver, the analog to digital converter, and the hardware adder. The high-sensitivity receiver has a dynamic range of 70 dB and a video bandwidth of 1 MHz. Phase coding schemes are applied, in particular for investigations at mesospheric heights, in order to carry out measurements with the maximum duty cycle and the maximum height resolution. The computer takes the data from the adder to store it in magnetic tape or disc. The radar controller is programmed by the computer using simple FORTRAN IV statements. After the program has been loaded and the computer has started the radar controller, it runs automatically, stopping at the program end. In case of errors or failures occurring during the radar operation, the radar controller is shut off caused either by a safety circuit or by a power failure circuit or by a parity check system.

Schmidt, G.; Ruster, R.; Czechowsky, P.

1983-01-01

160

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

SciTech Connect

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

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

1996-09-01

161

Portable radar simulator  

NASA Astrophysics Data System (ADS)

A portable radar simulator, when connected to a transmitting means such as a waveguide horn antenna, provides a radar signal to test a radar receiver. The portable radar simulator comprises a tunable oscillator which generates a continuous wave signal in the microwave frequency range with the desired frequency of the signal being selected by an operator. The signal generated by the tunable oscillator is supplied to a microwave switch. The microwave switch receives a control signal provided by a pulse repetition frequency generating circuit and in response to the control signal turns the switch on or off controlling the transmission of the oscillator generated signal to the wave guide horn antenna. The pulse repetition frequency generating circuit which comprises an integrated circuit timer and a monostable multivibrator provides a variable frequency and variable pulse width control signal. The frequency and pulse width of the control signal are, in turn, set by the operator.

Aw, Kenneth

1992-09-01

162

Powerful ultrawideband rf emitters: status and challenges  

Microsoft Academic Search

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

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

1995-01-01

163

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

164

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

NASA Astrophysics Data System (ADS)

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

Baras, John S.; Wolk, Sheldon I.

1995-04-01

165

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. PMID:18044958

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

2008-01-01

166

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

E-print Network

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

Barrash, Warren

167

In vessel detection of delayed neutron emitters from clad failure in sodium cooled nuclear reactors: An estimation of the signal  

NASA Astrophysics Data System (ADS)

The detection of clad failures is mandatory in sodium-cooled fast neutron reactors in compliance with the clean sodium concept. An in-vessel detection system, sensitive to delayed neutrons from fission products released into the primary coolant by failures, partially tested in SUPERPHENIX, is foreseen in current SFR projects in order to reduce significantly the delay before an alarm is issued. In this paper, an estimation of the signal received by such a system in case of a failure is derived, taking the French project ASTRID as a working example. This failure induced signal is compared to that of the contribution of the neutrons from the core itself. The sensitivity of the system is defined in terms of minimal detectable surface of clad failure. Possible solutions to improve this sensitivity are discussed, involving either the sensor itself, or the hydraulic design of the vessel in the early stage of the reactor conception.

Filliatre, P.; Jammes, C.; Chapoutier, N.; Jeannot, J.-P.; Jadot, F.; Batail, R.; Verrier, D.

2014-04-01

168

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

NASA Astrophysics Data System (ADS)

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

Alejos, Ana Vazques; Dawood, Muhammad

2012-06-01

169

A novel LPI radar signal based on hyperbolic frequency hopping combined with Barker phase code  

Microsoft Academic Search

In tins paper we address the problem of low probability of intercept (LPI) techniques. Previous LPI signals are first reviewed, and then the characteristic of frequency hopping techniques and barker phase code is investigated. A new LPI signal called PR-FH is brought forward by combining the Barker sequences and hyperbolic frequency hop code and compared with the PSK Costas-frequency hopping

Hou Jiaiigang; Tao Ran; Shan Tao; Qi Llll

2004-01-01

170

Ground-Penetrating Radar vertical resolution, signal attenuation, and penetration in temperate and polar glaciers: Case studies from North America and Antarctica  

NASA Astrophysics Data System (ADS)

The application of commercially available ground-penetrating radar (GPR) has become a standard routine for many field glaciological research efforts. However, the success of glaciological radar surveys often depends on frequency selection, tunable parameters, and data collection methods relative to the glaciological setting. Specifically, glaciers exhibit a range of thermal properties (i.e. cold, polythermal, temperate) and exist under diverse settings (e.g. maritime, continental, mountain glaciers, ice sheets, ice streams), each which present unique and complex challenges for conducting radar surveys. Herein, we review over 1000 km of ground collected GPR data from polar and temperate settings and distill vertical resolution, signal attenuation, and depth of penetration for various recording and antenna configurations ranging between 15-900 MHz. Snow and firn studies, ice thickness measurements, and ice flow dynamics studies from Alaska, Antarctica, Canada, and the Western United States will be referenced.

Campbell, S. W.; Kreutz, K. J.; Arcone, S. A.

2013-12-01

171

Radar detection of signals with unknown parameters in K-distributed clutter  

Microsoft Academic Search

The detection of signals with unknown parameters in correlated K-distributed noise, using the generalized Neyman-Pearson strategy, is considered. The a priori uncertainty on the signal is removed by performing a maximum likelihood estimate of the unknown parameters. The resulting receivers can be regarded as a generalization of the conventional detector, but for a zero-memory nonlinearity depending on the amplitude probability

E. Conte; M. Longo; M. Lops; S. L. Ullo

1991-01-01

172

1999 IEEE radar conference  

SciTech Connect

This conference addresses the stringent radar technology demands facing the next century: target detection, tracking and identification; changing target environment; increased clutter mitigation techniques; air traffic control; transportation; drug smuggling; remote sensing, and other consumer oriented applications. A timely discussion covers how to minimize costs for these emerging areas. Advanced radar technology theory and applications are also presented. Topics covered include: signal processing; space time adaptive processing/antennas; surveillance technology; radar systems; dual use; and phenomenology.

NONE

1999-07-01

173

Horava-Lifshitz gravity: calculation of radar signal delay contribution in the vicinity of the Sun in the Kehagias-Sfetsos solution  

NASA Astrophysics Data System (ADS)

There has been a renewed interest in the recent years for the study of gravitational theories alternative to General Relativity (GR). This results from current observations that seem to question the role of General Relativity theory at large distances, i.e., galactic and cosmological ones. An example of such theories is that of Modified Newtonian Dynamics or (MOND). In an effort for a description of gravitation in a quantum framework Horava has recently proposed the Horava-Lifshitz gravity (HL). Our goal is to study the effect of radar signal delays in the vicinity of the sun for the Kehagias-Sfetsos space-time solution of the Horava-Lifshitz modified gravity. For that we use a spherically symmetric modified solar system space-time metric and we calculate the radar signal delay correction as a function of the non-dimensional HL parameter ?. Next expressing ? as a function of the planetary orbital elements we derive an expression for the Kehagias-Sfetsos radar time delay solution, which next calculate for all the planets in the solar system excluding Pluto. Finally, for the planets Mercury to Neptune, we obtain radar time delays in the range of 531 10^{-9} ps ? t_{{KS}_{{MER}}} ? 5379.86 ps for the planets Mercury to Neptune.

Haranas, Ioannis; Ragos, Omiros; Gkigkitzis, Ioannis

2011-10-01

174

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

175

Cytostatic response of NB69 cells to weak pulse-modulated 2.2?GHz radar-like signals.  

PubMed

The present study investigates the response of two human cancer cell lines to a 24-h treatment with a 2.2-GHz, pulse-modulated (5?s pulse duration, 100?Hz repetition rate) radar-like signal at an average SAR?=?0.023?W/kg, using a newly designed setup for in vitro exposure to radiofrequency (RF) fields. A complete discretized model of the setup was created for numerical dosimetry using finite-difference time-domain (FDTD) software, SEMCAD X. The average dose of RF radiation absorbed by the cultures was calculated to be subthermal (?T?

Trillo, Mara A; Cid, Mara Antonia; Martnez, Maria Antonia; Page, Juan E; Esteban, Jaime; beda, Alejandro

2011-07-01

176

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

177

Emittance Theory for Cylindrical Fiber Selective Emitter  

NASA Technical Reports Server (NTRS)

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

Chubb, Donald L.

1998-01-01

178

Emittance Theory for Cylindrical Fiber Selective Emitter  

NASA Technical Reports Server (NTRS)

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

Chubb, Donald L.

1998-01-01

179

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

NASA Astrophysics Data System (ADS)

In using GPR images for landmine detection it is often useful to identify the air-ground interface in the GRP signal for alignment purposes. A common simple technique for doing this is to assume that the highest return in an A-scan is from the reflection due to the ground and to use that as the location of the interface. However there are many situations, such as the presence of nose clutter or shallow sub-surface objects, that can cause the global maximum estimate to be incorrect. A Support Vector Data Description (SVDD) is a one-class classifier related to the SVM which encloses the class in a hyper-sphere as opposed to using a hyper-plane as a decision boundary. We apply SVDD to the problem of detection of the air-ground interface by treating each sample in an A-scan, with some number of leading and trailing samples, as a feature vector. Training is done using a set of feature vectors based on known interfaces and detection is done by creating feature vectors from each of the samples in an A-scan, applying the trained SVDD to them and selecting the one with the least distance from the center of the hyper-sphere. We compare this approach with the global maximum approach, examining both the performance on human truthed data and how each method affects false alarm and true positive rates when used as the alignment method in mine detection algorithms.

Wood, Joshua; Wilson, Joseph

2011-06-01

180

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

SciTech Connect

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

Ormesher, Richard C.; Bickel, Douglas L

2012-10-23

181

Radar Detection using Sparsely Distributed Apertures in Urban Environment  

E-print Network

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

Yazici, Birsen

182

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

183

Radar Technology Applied to Air Traffic Control  

Microsoft Academic Search

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

WILLIAM W. SHRADER

1973-01-01

184

Noise modulated multistatic surveillance radar concept  

Microsoft Academic Search

Noise modulated surveillance radars have many desirable properties. However, practical problems with signal processing and system design have inhibited noise modulated radars to become common. Fast improving signal processing will probably change this in future. We have studied what kind of noise modulated radar might be realistic in 15 years. Advantages are good LPI, good ECCM, good ARM avoidance, good

Vesa-Jukka Salminen; Timo Lensu; Pekka Eskelinen; Simo Mertanen

2006-01-01

185

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

186

Eliminating Clutter in Synthetic-Aperture Radar  

NASA Technical Reports Server (NTRS)

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

Jain, A.

1979-01-01

187

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

NASA Astrophysics Data System (ADS)

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

Dean, A. M.

1992-11-01

188

Intrapulse Radar-Embedded Communications  

Microsoft Academic Search

The embedding of a covert communication signal amongst the ambient scattering from an incident radar pulse has previously been achieved by modulating a Doppler-like phase shift sequence over numerous pulses (i.e., on an inter-pulse basis). In contrast, this paper considers radar-embedded communications on an intrapulse basis whereby an incident radar waveform is converted into one of $K$ communication waveforms, each

Shannon D. Blunt; Padmaja Yatham; James Stiles

2010-01-01

189

Diamond fiber field emitters  

DOEpatents

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

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

1996-01-01

190

Radar Entomology  

NSDL National Science Digital Library

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

0000-00-00

191

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

192

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

193

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

194

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

195

Wideband radar (advantages and problems)  

Microsoft Academic Search

Review of advantages and problems of wideband radar is given. Some criteria of wideband (UWB) radar are discussed to avoid misunderstanding when only the relative signal bandwidth is used as a criterion. Brief historical outline of the first and follow up experiments by different authors is presented. Advantages and disadvantages of bandwidth widening can be compared using the computer simulation

Y. D. Shirman; S. P. Leshchenko; V. M. Orlenko

2004-01-01

196

Frequency diversity in multistatic radars  

Microsoft Academic Search

This paper presents the model and analysis of a frequency-diverse radar system. Multistatic radar systems provide an inherent spatial diversity by processing signals from different platforms which view a potential target from different aspect angles. By using different frequencies at each platform, an additional diversity gain can be obtained on top of the advantages of spatial diversity. Here, since platforms

Byung Wook Jung; R aviraj S. Adve; Joohwan Chun

2008-01-01

197

Emittance studies with an Allison scanner  

SciTech Connect

The Spallation Neutron Source H{sup -} source on the ion source test stand is being used to study the emittance of the H{sup -}-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. [SNS, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831 (United States); Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)

2006-03-15

198

Emittance Scanner Optimization for Low-Energy Ion Beams  

Microsoft Academic Search

Ion beam emittances are normally measured as two-dimensional distributions of the beam current fraction within a narrow window ?x centered at position coordinate x and a narrow window ?x? centered at trajectory angle x?. The small fraction of the beam current found within both of these windows causes the measured emittance signals to be sensitive to noise, bias, and other

M. P. Stockli; R. F. Welton

2005-01-01

199

Application of field emitter arrays to microwave power amplifiers  

Microsoft Academic Search

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

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

2000-01-01

200

Simple Sea Clutter Canceller for Noise Radar  

Microsoft Academic Search

In the last decade the noise radar technology is intensively investigated. The low transmitting power and nonspecific waveform makes that the noise radar has very god LPI properties. The simultaneous emission and reception of signals in such kind of radars make them sensitive to near-far problem. Strong echoes, originated from ground clutter can completely mask the weak target return. In

Krzysztof Kulpa

2006-01-01

201

Effect of scattering on radar system performance  

NASA Astrophysics Data System (ADS)

The effect of both forward and backward scattering effect on the performance of radar systems was investigated. It is shown that forward scatter causes considerable error in the target elevation in tracking radars. Thus, low angle tracking radars are greatly affected by specular reflection whereas airborne tracking radars are affected by forward scatter. The backscattered signal (clutter) reduces the maximum range of the pulse radar to a great extent. Finally, the radar range decreases rapidly with increasing grazing angles. This implies that the probability of detection of a target decreases as the grazing angle increases.

Vishvakarma, Babau Ram; Taha, Bazil; Al-Hafid, H. T.

202

A study of frequency diversity MIMO radar beamforming  

Microsoft Academic Search

Compared to traditional phased-array radar, multiple-input multiple-output (MIMO) radar can transmit multiple probing signals that are correlated or uncorrelated with each other. An interesting current research topic in MIMO radar is the frequency diversity MIMO (f-MIMO) radar. The frequency between two adjacent transmitted signals of f-MIMO radar are not identical but stepped uniformly at the same time. In this paper,

Xiang-Ru Li; Zhao Zhang; Wu-Xing Mao; Xiao-Mo Wang; Jun Lu; Wen-Sheng Wang

2010-01-01

203

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

204

A complementary filtering technique for deriving aircraft velocity and position information. [onboard navigation system and radar tracking signals for instrument landing approach guidance  

NASA Technical Reports Server (NTRS)

An onboard navigation system which employed complementary filtering was developed to provide velocity and position information. The inputs to the mix filter included both acceleration inputs, which provided high-frequency position and velocity information, and radar position inputs, which provided the low-frequency position and velocity information. Onboard aircraft instrumentation, including attitude reference gyros and body-mounted accelerometers, was used to provide the acceleration information. An in-flight comparison of signal quality and accuracy showed good agreement between the complementary filtering system and an aided inertial navigation system. Furthermore, the complementary filtering system was proven to be satisfactory in control and display system applications for both automatic and pilot-in-the-loop instrument approaches and landings.

Niessen, F. R.

1975-01-01

205

Real-time parallel implementation of Pulse-Doppler radar signal processing chain on a massively parallel machine based on multi-core DSP and Serial RapidIO interconnect  

NASA Astrophysics Data System (ADS)

Pulse-Doppler radars require high-computing power. A massively parallel machine has been developed in this paper to implement a Pulse-Doppler radar signal processing chain in real-time fashion. The proposed machine consists of two C6678 digital signal processors (DSPs), each with eight DSP cores, interconnected with Serial RapidIO (SRIO) bus. In this study, each individual core is considered as the basic processing element; hence, the proposed parallel machine contains 16 processing elements. A straightforward model has been adopted to distribute the Pulse-Doppler radar signal processing chain. This model provides low latency, but communication inefficiency limits system performance. This paper proposes several optimizations that greatly reduce the inter-processor communication in a straightforward model and improves the parallel efficiency of the system. A use case of the Pulse-Doppler radar signal processing chain has been used to illustrate and validate the concept of the proposed mapping model. Experimental results show that the parallel efficiency of the proposed parallel machine is about 90%.

Klilou, Abdessamad; Belkouch, Said; Elleaume, Philippe; Le Gall, Philippe; Bourzeix, Franois; Hassani, Moha M'Rabet

2014-12-01

206

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

207

Terrain Analysis Using Radar Shape-from-Shading  

E-print Network

process to real world radar data, we require probabilistic models for the appearance of terrain features. The extent of the envelope depends on the corrected radar reflectance and the variance of the radar signal of terrain, foreshortening, layover, shadowing, man-made objects, or the process of radar image acquisition

Bors, Adrian

208

Design of a miniature wideband radar experimental system  

Microsoft Academic Search

Wideband radars have been found more important both in civil and military applications. Micromation is one key technology for radars mounted at missiles, unmanned aerial vehicles (UAV), satellites, etc. The scheme of a miniature wideband radar experimental system is introduced in this paper, while the design and implementation of a wideband signal generator is analyzed in detail. The radar is

Zhang Xiao-wei; Li Ming; Zuo Lei

2011-01-01

209

Radar detection in clutter  

Microsoft Academic Search

Clutter is defined as any unwanted radar return. The presence of clutter in a range\\/Doppler cell complicates the detection of a target return signal in that cell. In order to quantify the effect of clutter on the probability of detection, we must first specify sets of models suitable for representing the clutter and target. The simplest and most common model

D. A. Shnidman

2005-01-01

210

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

211

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

212

A Bistatic Parasitical Radar (BIPAR)  

NASA Astrophysics Data System (ADS)

After decades of remote sensing from aircraft and satellites with cameras and other optical sensors, earth observation by imaging radars becomes more and more suitable because of their night and day and all weather operations capability and their information content being complementary to those of optical sensors. The major problem with microwave sensors (radars) is that there are not enough of them presently in operation and therefore not enough data available for effective radar signature research for civil applications. It is shown that airborne bistatic real aperture radar receivers can be operated with spaceborne transmitters of opportunity. Famous candidates for those systems are high power communications or direct TV satellites illuminating the earth surface with a power denisty of more than 10(-12) Watt/sq meter. The high sophisticated status of signal processing technology today allows the realization of receivers correlating the received direct path signal from a communications satellite with its avoidable reflection on the ground. Coherent integration can improve the signal to noise ratio up to values where the radiometric resolution can satisfy users needs. The development of such parasitic radar receivers could even provide a cost effective way to open up new frequency bands for radar signature research. Advantages of these quiet systems for the purpose of classical radar reconnaissance are evident.

Hartl, Philipp; Braun, Hans Martin

1989-01-01

213

Distance and velocity estimation of projectiles based on Doppler radar signals using a nonlinear discrete-time observer  

NASA Astrophysics Data System (ADS)

We propose a new "quasi-global" observer design to determine the distance and velocity of projectiles in real-time. The detection of the projectile is realized by a low power Doppler radar at short distances (5m-10m). The advantage of a global observer design is the possibility to deal with large initial errors, which is important because of the usually unknown initial state of the observed system. The transformation to the nonlinear observability canonical form (NOCF) leads to linear error dynamics and this allows a traceable influence on the dynamic behaviour of the observer, which is essential for the time critical implementation on a real-time system. To benefit from these two advantages, the nonlinear system has to be transformed to the NOCF and an explicit expression of the inverse transformation has to be found. Since with this severe restriction the given problem can not be solved, we propose a numerically approximated inverse transformation in a bounded region of physical interest to allow the design of a quasi-global observer with linear error dynamics in the presented case. Based on this design the class of systems where this kind of observer can be applied has been enlarged considerably.

Podjawerschek, Sonja; Spahn, Emil; Horn, Joachim; Brodmann, Michael; Himmelsbach, Ralf

2010-04-01

214

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

215

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; B. J. Wessels; P. Van Genderen

2000-01-01

216

LPI Radar Systems with Spatial Feedback  

Microsoft Academic Search

The radar system with spatial feedback is considered. In this system there are self-oscillations, if the system is closed through a space of the signal radio-path and the target. When the target is absent (system is not closed), transmitter output power of the noise signal is insignificant, and that complicates detection of the radar radiation. In the report principles of

V. M. Kutuzov; S. P. Kalenichenko

2006-01-01

217

Outdoor Radar Mapping Using Measurement Likelihood Estimation  

E-print Network

with the signal detection processing which occurs in a range sensor, and that the required measurement like. This is due to the radar's ability to penetrate dust, fog, and rain [2]. 2 Related Work Signal processing as fully known deterministic values. From examination of radar detection theory it is shown

Boyer, Edmond

218

Radar Ionospheric Impact Mitigation  

NASA Astrophysics Data System (ADS)

New ionospheric modeling technology is being developed to improve correction of ionospheric impacts on the performance of ground-based space-surveillance radars (SSRs) in near-real-time. These radars, which detect and track space objects, can experience significant target location errors due to ionospheric delay and refraction of the radar signals. Since these radars must detect and track targets essentially to the radar horizon, it is necessary to accurately model the ionosphere as the radar would observe it, down to the local horizon. To correct for spatial and temporal changes in the ionosphere the model must be able to update in near-real-time using ionospheric sensor data. Since many radars are in isolated locations, or may have requirements to operate autonomously, an additional required capability is to provide accurate ionospheric mitigation by exploiting only sensor data from the radar site. However, the model must also be able to update using additional data from other types of sensors that may be available. The original radar ionospheric mitigation approach employed the Bent climatological model. This 35-year-old technology is still the means employed in the many DoD SSRs today. One more recent approach used capabilities from the PRISM model. PRISM technology has today been surpassed by `assimilative models' which employ better physics and Kalman filtering techniques. These models are not necessarily tailored for SSR application which needs to optimize modeling of very small regions using only data from a single sensor, or very few. The goal is to develop and validate the performance of innovative and efficient ionospheric modeling approaches that are optimized for the small regions applicable to ground-based radar coverage (radius of ~2000 km at ionospheric altitudes) and somewhat beyond. These approaches must adapt a continuous modeling scheme in near-real-time to be consistent with all observational data that may become available, and degrade gracefully toward a climatological representation in the absence of data. In this presentation we will discuss the issues for improving correction of ionospheric impacts on SSRs, some of the capabilities and limitations of current models, and the requirements and goals for new modeling technologies.

Bishop, G.; Decker, D.; Baker, C.

2006-12-01

219

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

NASA Technical Reports Server (NTRS)

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

Fukao, Shoichiro (editor)

1989-01-01

220

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

221

Tracking system for photon-counting laser radar  

E-print Network

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

Chang, Joshua TsuKang

2007-01-01

222

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

223

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

PubMed

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

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

2015-02-01

224

All-digital radar architecture  

NASA Astrophysics Data System (ADS)

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

Molchanov, Pavlo A.

2014-10-01

225

Use of C-Band Ground Penetrating Radar to Determine Backscatter Sources Within Glaciers  

Microsoft Academic Search

The question of penetration of synthetic aperture radar (SAR) signals at C-band frequency into polar glaciers is addressed by comparing ground penetrating radar (GPR) and SAR backscatter signatures. Profiles of the Kongsvegen glacier, Svalbard, were obtained with a C-band GPR. The received signal is converted to the equivalent radar cross section using the standard radar equation, thus mapping the effective

Kirsty Langley; Svein-Erik Hamran; Kjell Arild Hogda; Rune Storvold; Ola Brandt; Jon Ove Hagen; Jack Kohler

2007-01-01

226

Radar transponder operation with compensation for distortion due to amplitude modulation  

SciTech Connect

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

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

2011-01-04

227

ECE 686: Introduction to Radar Systems Department of Electrical & Computer Engineering  

E-print Network

processes, and signals and systems. Required Text: Indroduction to Radar Systems, M.I. Skolnik, 3rd ed equation, signal-to-noise ratio, radar cross section, range and velocity ambiguity, radar clutter Sensing, Active & Passive Vol. II, Radar Remote Sensing and Surface Scattering and Emission Theory, F

Massachusetts at Amherst, University of

228

Emittance preservation in the LHC  

E-print Network

Emittance measurements during the LHC proton run 2011 indicated a blow - up of 20 % to 30 % from LHC injection to collisions. At the LHC design stage the total allowed emittance increase from SPS extraction to colliding beams was set to 7 %. This presentation will show the emittance preservation throughout the different parts of the LHC cycle and discuss the current limitations on emittance determination. Possible sources and cures for the observed blow - up will be presented. Possible improvements of emittance diagnostics and analysis tools together with a list of machine development tests in 2012 will also be shown.

Kain, V; Goddard, B; Holzer, B J; Jowett, J M; Meddahi, M; Mertens, T; Roncarolo, F; Schaumann, M; Versteegen, R; Wenninger, J

2012-01-01

229

Rare Earth Garnet Selective Emitter  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

230

AEGIS - Advanced Multi-Function Array Radar  

NASA Astrophysics Data System (ADS)

The AMFAR (Advanced Multi-Function Array Radar), a radar system technology developed in the late 1960s, has demonstrated automatic detection and tracking of all air targets plus inherent resistance to natural and man-made clutter with computer control of the radar. The major elements of the AMFAR - a high-power radar frequency transmitter, a phased-array antenna, a signal processor system, a computer control system, and an automated test system - are described in detail. The capabilities of the radar are demonstrated in a series of pictures showing processing steps to provide automatic target detection and track in both ground clutter zones and rain clutter. The success of AMFAR laid the foundation of Radar System AN/SPY-1A, the Weapon Control Radar System now being produced as a major element of the AEGIS Weapon System for the U.S. Navy guided missile cruiser Ticonderoga.

Phillips, C. C.

1981-12-01

231

Polarization diversity in radars  

Microsoft Academic Search

Many polarization techniques, which have been proposed and analyzed to enhance radar performance, are reviewed in this paper in order to assess the possible improvement they can provide in the signal-to-disturbance ratio, target detectability, target discrimination and resolution, and target classification and identification. Some recent experimentally-based results relating to these applications are also presented. Those techniques are emphasized for which

D. Giuli

1986-01-01

232

Software Radar Technology and the Open Radar Initiative  

NASA Astrophysics Data System (ADS)

We have recently implemented a Software Radar System as the production data taking and control system for the Millstone Hill Incoherent Scatter Radar. In a Software Radar the traditional real-time hardware control and signal processing elements of a radar system are replaced by software systems running on general purpose computer systems and interconnected by a high speed and low latency multicast network. From our efforts to develop this system we have identitified a number of architectural patterns which are important for achieving performance, modularity, and scalability in distributed systems for managing experimental instrumentation and the many terabytes of information that are produced. The most important of these patterns concern information organization and management in the system and they are general far beyond their application to ionospheric radar systems. After discussing our system and these patterns we will describe the Open Radar Initiative. This effort is an open source project to make Software Radar technology widely available and to ready it for use as the foundation of a ground based Global Space Weather Network.

Lind, F. D.; Grydeland, T.; Erickson, P. J.; Rideout, B.; Holt, J.

2002-12-01

233

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

234

Rare earth garnet selective emitter  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

235

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

236

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

237

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

238

ANALYZING SPATIAL DIVERSITY IN DISTRIBUTED RADAR NETWORKS  

Microsoft Academic Search

Abstract We introduce the notion of diversity order as a performance measure for distributed radar systems. We deflne the diversity order of a radar network as the slope of the probability of detection (PD) versus signal-to-noise ratio (SNR) curve evaluated at PD = 0:5. We prove that the diversity order of both joint detection and optimal binary detection grows as

Rani Daher

239

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

240

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

241

Autonomous Land Vehicle Navigation Using Millimeter Wave Radar  

Microsoft Academic Search

This paper discusses the use of a 77 GHz millimeter wave radar as a guidance sensor for autonomous land vehicle navigation. A test vehicle has been fitted with a radar and encoders that give steer angle and velocity. An extended Kalman filter optimally fuses the radar range and bearing measurements with vehicle control signals to give estimated position and variance

Steve Clark; Hugh F. Durrant-whyte

1998-01-01

242

Twin VHF radar for european space situation awareness system  

Microsoft Academic Search

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

Istvan Balajti

2012-01-01

243

Classification of radar clutter in an air traffic control environment  

Microsoft Academic Search

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

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

1991-01-01

244

CHARACTERIZATION OF A COOPERATIVE TARGET FOR GROUND-PENETRATING RADAR  

E-print Network

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

Kansas, University of

245

33 CFR 118.120 - Radar reflectors and racons.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

246

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

E-print Network

MIMO radar systems Permanent members: F. Nadal, P. Jardin. Associated researcher: S. Middleton. Multiple-input and multiple-output (MIMO) radar systems use arrays of transmitting and receiving antennas like phased array radars but while a phased array transmits highly correlated signals which form a beam

Baudoin, Geneviève

247

33 CFR 118.120 - Radar reflectors and racons.  

Code of Federal Regulations, 2013 CFR

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

2013-07-01

248

33 CFR 118.120 - Radar reflectors and racons.  

Code of Federal Regulations, 2014 CFR

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

2014-07-01

249

33 CFR 118.120 - Radar reflectors and racons.  

Code of Federal Regulations, 2012 CFR

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

2012-07-01

250

33 CFR 118.120 - Radar reflectors and racons.  

Code of Federal Regulations, 2011 CFR

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

2011-07-01

251

Convergence of ESM sensors and passive covert radar  

Microsoft Academic Search

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

Dietmar Matthes

2005-01-01

252

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

253

Reconfigurable Data Acquisition System for Weather Radar Applications  

E-print Network

powerful signal processing algorithms on the raw data collected by the radars. Following processing, data, Amherst MA Abstract-- Tornado, hazardous weather and flood detection radars demand high-throughput, high-based system has been successfully integrated with a radar optimized for tornado detection and deployed

Tessier, Russell

254

Automated Target Recognition Using Passive Radar and Coordinated Flight Models  

E-print Network

approach to ATR compares the Radar Cross Section (RCS) of targets detected by a passive radar systemAutomated Target Recognition Using Passive Radar and Coordinated Flight Models Lisa M. Ehrman and Aaron D. Lanterman Center for Signal and Image Processing School of Electrical and Computer Engineering

Lanterman, Aaron

255

SHORT-RANGE FMCW RADAR PLATFORM FOR MILLIMETRIC DISPLACEMENTS MEASUREMENT  

E-print Network

of the 8-12 GHz short range FMCW radar platform is shown in Fig. 1. The command signal is a linear tuningSHORT-RANGE FMCW RADAR PLATFORM FOR MILLIMETRIC DISPLACEMENTS MEASUREMENT Andrei Anghel Gabriel A frequency modulated continuous wave (FMCW) radar plat- form for millimetric displacement measurements

Paris-Sud XI, Université de

256

Solar Radar  

NASA Astrophysics Data System (ADS)

Radar echoes from the Sun were first detected in 1959 at 25 MHz and an extensive set of measurements was made at 38 MHz between 1960 and 1969. The results were unexpected and could not be explained at the time. Interest in the technique waned and radar astronomy evolved to the use of higher frequencies so it became impossible to repeat the measurements. The early observations can be explained in the light of our present understanding of the corona. New radar observations, with correlative optical, UV, and soft X-ray observations, would be very useful in probing the corona near the origin of the solar wind. Radar measures the range to the reflection point and the plasma velocity at the reflection point. Reflection occurs where the dielectric constant goes to zero, which is polarization dependent. Thus dual polarization observations provide estimates of the electron density, magnetic field, and velocity at the reflection point. Solar echoes can be observed at frequencies between 18 MHz and 100 MHz, corresponding to reflection heights between (roughly) 1.8 Rs and 1.15 Rs. It may be possible to operate up to 200 MHz and probe to the edge of the transition region. Here we will review the early observations; explain their basic features; outline existing and potential opportunities for new observations; and speculate on the future development of the technique.

Coles, W. A.

2002-12-01

257

Lightweight SAR GMTI radar technology development  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

258

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

Microsoft Academic Search

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

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

2003-01-01

259

Polarization radar processing technology  

NASA Astrophysics Data System (ADS)

A comprehensive effort involving measurements and performance evaluation for the detection of scatterers immersed in a background of natural and man-made clutter using polarization diverse waveforms is presented. The effort spans evaluation from the initial stages of theoretical formation to processor performance evaluation using real-world data. The theoretical approach consists of determining polarimetric statistical properties of the backscatter waveform and these properties to derive the optimum dual-polarized S-band radar system with selectable polarization on both transmit and receive. Several processors utilizing optimum and suboptimum algorithms were evaluated using simulated and live radar data, and performance results are compared. The processor types include fully adaptive algorithms designed to operate on polarimetric spectral spread waveforms, and several combinations of single channel and polarization diverse receivers with both single and dual transmit polarization. Results are plotted and evaluated by displaying probability of detection as a function of signal-to-noise ratio with processor type as a parameter.

Wicks, Michael C.; Vannicola, Vincent C.; Stiefvater, Kenneth C.; Brown, Russell D.

260

LPI Radar detection: SNR performances for a dual channel Cross-Correlation based ESM Receiver  

Microsoft Academic Search

Detection of low probability of intercept (LPI) radar signal is an important issue for an electronic support measure (ESM) receiver. In the present work a LPI radar signal is assumed to be phase modulated by a code. The ESM receiver does not have any knowledge of the modulating code and carrier frequency of the LPI radar signal; it can only

Riccardo Ardoino; Andrea Megna

2009-01-01

261

Eliminating Doppler Effects in Synthetic-Aperture Radar Optical Processors  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

262

A satellite-based radar wind sensor  

NASA Technical Reports Server (NTRS)

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

Xin, Weizhuang

1991-01-01

263

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

264

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

265

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

266

Securing radars using secure wireless sensor networking  

NASA Astrophysics Data System (ADS)

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

Tahmoush, David

2014-06-01

267

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

E-print Network

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

Elsherbeni, Atef Z.

268

Experimental Results of Air Target Detection With a GPS Forward-Scattering Radar  

Microsoft Academic Search

Forward-scattering radars (FSRs) acquire great interest when low radar cross section (RCS) targets are willing to be detected. This type of radar provides a countermeasure to stealth technology because, here, the targets' RCS depends only on the size and the shape of their silhouette. Passive radars use transmitters of opportunity as signal source, and they are therefore attractive too, due

Ion Suberviola; Iker Mayordomo; Jaizki Mendizabal

2012-01-01

269

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

270

Weather Radar Fundamentals  

NSDL National Science Digital Library

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

COMET

2012-03-21

271

Ground clutter cancellation in incoherent radars: solutions for EISCAT Svalbard radar  

E-print Network

Ground clutter cancellation in incoherent radars: solutions for EISCAT Svalbard radar T. Turunen1 clutter signals, entering via the antenna side lobes, can render measurements at the nearest target ranges ground clutter and the ionosphere cannot be measured in any simple manner at ranges less than about 120

Paris-Sud XI, Université de

272

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

273

Emittance and Phase Space Exchange  

SciTech Connect

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

Xiang, Dao; Chao, Alex; /SLAC

2011-08-19

274

Infrared emittance of fibrous materials.  

PubMed

A theory of the IR emittance of fibrous materials has been developed. The theory predicts the IR spectral emittance of a matte of randomly arrayed cylindrical fibers as a function of the optical constants of the fiber material, the fiber diameter, the packing density of the fibers, the packing of the fibers within fiber bundles, the reflectance of the substrate, and the thickness of the fabric layer. Theoretical simulations were made and compared with experimental measurements of the IR emittance of polypropylene samples. Both the theory and the experimental data confirm the validity of the concept that fabrics can be tailored by a proper choice of the above parameters so as to obtain an emittance distinctly different from unity. PMID:20212721

Aronson, J R; Emslie, A G; Ruccia, F E; Smallman, C R; Smith, E M; Strong, P F

1979-08-01

275

Evaluation of Transmit Diversity in MIMO-Radar Direction Finding  

Microsoft Academic Search

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

Nikolaus H. Lehmann; Eran Fishler; Alexander M. Haimovich; Rick S. Blum; Dmitry Chizhik; Reinaldo A. Valenzuela

2007-01-01

276

Selected tendencies of modern radars and radar systems development  

Microsoft Academic Search

This paper presents modern radars and radar systems problems caused by troubles and dangers connected with actual battlefield conditions. The usefulness of the phased array radar (PAR), low probability of intercept (LPI) radar and the multi-junction radar (MFR) has been described from the point of view of the single radar using. Moreover chosen aspects of the modem radar systems development,

J. F. Pietrasinski; T. W. Brenner; C. J. Lesnik

1998-01-01

277

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

E-print Network

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

278

On the design of a 2D array HF skywave radar  

Microsoft Academic Search

New generation of HF skywave radars moves toward 2D array solution to get high signal to noise ratio (SNR), low probability of intercept (LPI), precise electronic scanning, faster scanning time. Critical elements for the design of such a system are radar configuration, antenna design, transmission waveforms and architecture, signal processing, radar management and control system. The goal of this paper

F. Berizzi; E. Dalle Mese; A. Monorchio; A. Capria; R. Soleti

2008-01-01

279

Design of X-Band FMCW Short Range Radar Dong-hun Shin*  

E-print Network

pulse signal or continuous-wave signals for the range detection. Pulse radar can detect the distance modulation continuous wave (FMCW) radar can detect the distance of multiple targets and the speed of a movingDesign of X-Band FMCW Short Range Radar Dong-hun Shin* Dept. of Electrical Engineering KAIST

Park, Seong-Ook

280

ECE 686: Introduction to Radar Systems Department of Electrical & Computer Engineering  

E-print Network

equation, signal-to-noise ratio, radar cross section, range and velocity ambiguity, radar clut- ter background in electromagnetic fields, probability and random processes, and signals and systems. Required., 1993, Academic Press, ISBN 0-12-221422-6. "Microwave Remote Sensing, Active & Passive Vol. II, Radar

Massachusetts at Amherst, University of

281

A DDS and PLL-based X-band FMCW Radar System  

E-print Network

the quality of the received IF signals. A voltage controlled oscillator (VCO) commonly used in FMCW radar-band FMCW radar system whose VCO nonlinearity is controlled by a digitally generated reference signalA DDS and PLL-based X-band FMCW Radar System Yun-Taek Im, Jee-Hoon Lee, and Seong-Ook Park

Park, Seong-Ook

282

Statistical radar imaging of diffuse and specular targets using an expectation-maximization algorithm  

E-print Network

waveforms, passive radar applications12 which employ commercial television or FM radio signals have garnered 61801 ABSTRACT Radar imaging is often posed as a problem of estimating deterministic reflectances (Ref. 10, Sec. 10.4.2), and random signal radar (RSR) waveforms.11 In addition to these active

Lanterman, Aaron

283

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

284

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

285

Ground penetrating radar signal processing improves mapping accuracy of underground voids and seawater table: an application in deteriorating coastal structure, Nanfangao Port, Taiwan  

Microsoft Academic Search

Efficient restoration of deteriorating coastal structures requires an accurate picture of both above ground and underground\\u000a features. Although ground penetrating radar (GPR) can map underground features, it creates reflection artifacts. Here, a model\\u000a for deconvolution calibration was developed in an outdoor small-scale experiment. GPR parameters were established, then applied\\u000a at a deteriorating fishing port in northeast Taiwan. The deconvolution filter

Yun-Li Chen; Joseph Jinder Chow

2007-01-01

286

Netted radar sensing  

Microsoft Academic Search

Future radar applications are beginning to stretch monostatic radar systems beyond their fundamental sensitivity and information limits. Networks of smaller radar systems can offer a route to overcome these limitations; for example, networks of radar sensors can counter stealth technology whilst simultaneously providing additional information for improved target classification. More generally, multiple independent sensors can provide an energetically more efficient

C. J. Baker; A. L. Hume

2003-01-01

287

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

288

Radar Location Equipment Development Program: Phase I  

SciTech Connect

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

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

1985-06-01

289

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

290

Comet radar explorer  

NASA Astrophysics Data System (ADS)

The Comet Radar Explorer (CORE) is designed to perform a comprehensive and detailed exploration of the interior, surface, and inner coma structures of a scientifically impor-tant Jupiter family comet. These structures will be used to investigate the origins of cometary nuclei, their physical and geological evolution, and the mechanisms driving their spectacular activity. CORE is a high heritage spacecraft, injected by solar electric propulsion into orbit around a comet. It is capable of coherent deep radar imaging at decameter wavelengths, high resolution stereo color imaging, and near-IR imaging spectroscopy. Its primary objective is to obtain a high-resolution map of the interior structure of a comet nucleus at a resolution of 100 elements across the diameter. This structure shall be related to the surface geology and morphology, and to the structural details of the coma proximal to the nucleus. This is an ideal complement to the science from recent comet missions, providing insight into how comets work. Knowing the structure of the interior of a comet-what's inside-and how cometary activity works, is required before we can understand the requirements for a cryogenic sample return mission. But more than that, CORE is fundamental to understanding the origin of comets and their evolution in time. The mission is made feasible at low cost by the use of now-standard MARSIS-SHARAD reflec-tion radar imaging hardware and data processing, together with proven flight heritage of solar electric propulsion. Radar flight heritage has been demonstrated by the MARSIS radar on Mars Express (Picardi et al., Science 2005; Plaut et al., Science 2007), the SHARAD radar onboard the Mars Reconnaissance Orbiter (Seu et al., JGR 2007), and the LRS radar onboard Kaguya (Ono et al, EPS 2007). These instruments have discovered detailed subsurface structure to depths of several kilometers in a variety of terrains on Mars and the Moon. A reflection radar deployed in orbit about a comet will enjoy significant simplifying benefits compared to using the same instrument for Mars or lunar radar science: (1) The proximity of operations leads to a much higher signal to noise, as much as +30 dB. (2) The lack of an ionosphere simplifies data modeling and analysis. (3) The body is globally illuminated during every data acquisition, minimizing ambiguity or 'clutter' and allowing for tomographic reconstruction. What is novel is the data processing, where instead of a planar radargram approach we coherently process the data into an image of the deep interior. CORE thus uses a MARSIS-SHARAD heritage radar to make coherent reflection sounding measurements, a 'CAT SCAN' of a comet nucleus. What is unique about this mission compared to the Mars radars mentioned above, is that the target is a finite mass of dirty ice in free space, rather than a sheet of dirty ice draped on a planet surface. The depth of penetration (kilometers), attainable resolution (decameters), and the target materials, are more or less the same. This means that the science story is robust, and the radar implementation is robust. The target is comet 10P/Tempel 2, discovered by Wilhelm Tempel in 1873 and observed on most apparitions since. It has been extensively studied, in part because of interest as a CRAF target in the mid-1980s, and much is known about it. Tempel 2 is one of the largest known comet nuclei, 1688 km (about the same size as Halley) [1] and has rotation period 8.9 hours [3,5,6,7,9]. The spin state is evolving with time, spinning up by 10 sec per perihelion pass [5,7]. The comet is active, but not exceedingly so, especially given its size. The water production is measured at 4 1028 mol/sec at its peak [2], a factor of 25 lower than comet Halley, and it is active over only 2% of its surface. The dust environment is well known, producing a factor of 100 less dust than Halley. Comet References: [1] A'Hearn et al., ApJ 347, 1155, 1989 [2] Feldman and Festou, ACM 1991, p. 171, 1992 [3] Jewitt and Luu, AJ 97, 1766, 1989 [4] Lamy et al., Comets II p 223. 2009 [5] Muel

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

291

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

292

Radar simulation program upgrade and algorithm development  

NASA Technical Reports Server (NTRS)

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

Britt, Charles L.

1991-01-01

293

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

294

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

295

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

296

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

297

Thermionic converter emitter support arrangement  

DOEpatents

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

Allen, Daniel T. (La Jolla, CA)

1990-01-01

298

Thermionic converter emitter support arrangement  

DOEpatents

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

Allen, Daniel T. (La Jolla, CA)

1990-01-01

299

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

300

Digital orthogonal receiver for wideband radar based on compressed sensing  

NASA Astrophysics Data System (ADS)

Digital orthogonal receiver is one of the key techniques in digital receiver of soft radar, and compressed sensing is attracting more and more attention in radar signal processing. In this paper, we propose a CS digital orthogonal receiver for wideband radar which utilizes compressed sampling in the acquisition of radar raw data. In order to reconstruct complex signal from sub-sampled raw data, a novel sparse dictionary is proposed to represent the real-valued radar raw signal sparsely. Using our dictionary and CS algorithm, we can reconstruct the complex-valued radar signal from sub-sampled echoes. Compared with conventional digital orthogonal radar receiver, the architecture of receiver in this paper is more simplified and the sampling frequency of ADC is reduced sharply. At the same time, the range profile can be obtained during the reconstruction, so the matched filtering can be eliminated in the receiver. Some experiments on ISAR imaging based on simulated data prove that the phase information of radar echoes is well reserved in our orthogonal receiver and the whole design is effective for wideband radar.

Hou, Qingkai; Liu, Yang; Chen, Zengping; Su, Shaoying

2014-10-01

301

High-resolution noise radar using slow ADC  

NASA Astrophysics Data System (ADS)

Conventional digital signal processing scheme in noise radars has some limitations related to combination of high resolution and high dynamic range. Those limitations are caused by a tradeoff in performance of currently available ADCs: the faster is ADC the smaller is its depth (number of bits) available. Depth of the ADC determines relation between the smallest and highest observable signals and thus limits its dynamic range. In noise radar with conventional processing the sounding and reference signals are to be digitized at intermediate frequency band and to be processed digitally. The power spectrum bandwidth of noise signal which can be digitized with ADC depends on its sampling rate. The bandwidth of radar signal defines range resolution of any radar: the wider the spectrum the better the resolution. Actually this is the main bottleneck of high resolution Noise Radars: conventional processing doesn't enable to get both high range resolution and high dynamic range. In the paper we present a way to go around this drawback by changing signal processing ideology in noise radar. We present results of our consideration and design of high resolution Noise Radar which uses slow ADCs. The design is based upon generation of both probing and reference signals digitally and realization of their cross-correlation in an analog correlator. The output of the correlator is a narrowband signal that requires rather slow ADC to be sampled which nowadays may give up to 130 dB dynamic range.

Lukin, Konstantin; Vyplavin, Pavlo; Zemlyanyi, Oleg; Lukin, Sergiy; Palamarchuk, Volodymyr

2011-06-01

302

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

303

Emittance concept and growth mechanisms  

SciTech Connect

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

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

1996-05-01

304

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

305

Ground emitter localization via fusing terrain map and DOA measurements using two miniature UASs  

NASA Astrophysics Data System (ADS)

This paper presents an emitter localization technique based on the fusion of Direction of Arrival (DOA) measurements obtained from two miniature unmanned aerial systems (UAS) and the terrain map of the interested area. The system's objective is to localize an emitter distributed in an area with 2000m radius in real time and the localization error is less than 100m with 95% confidence. In the system, each UAS is equipped with a three-element smart antenna for scanning the desired frequency band, calculating the received signal's spectrum signature and estimating the emitter's elevation and azimuth DOA. The received signal's DOA, spectrum signature, UAS position, and the time that the signal is received (calculated with respected to the pulse per second (PPS) signal of global positioning system (GPS)) are transmitted to the ground control station. At the ground control station, the DOA coming from the two UAS are aligned using the received signal's spectrum signature and time stamp, and then fused with the UAS position and terrain map to localize the emitter. This paper is focused on the localization scheme including the DOA estimation and emitter localization based on data fusion. The simulation conducted shows that azimuth DOA error (about 1.5) is much smaller than elevation DOA error (about 5), and the achieved localization error is less than 100m in most cases when the UAS and the emitter are located in an area with radius of 2000m.

Wang, Zhonghai; Blasch, Erik; Pham, Khanh; Shen, Dan; Lin, Peter

2012-06-01

306

Radar tomography  

NASA Astrophysics Data System (ADS)

Results of experimental researches on radar sounding of non-uniform mediums and objects with use as multi frequency scanning in a UWB strip (from 0.5 up to 17 GHz), and sub nanosecond impulses are considered. It is shown, that addition of measurements by angular and spatial scanning with SAR technologies to realize 3-D tomography inhomogeneous with the spatial resolutions about 1 cm at the physical models of interaction of electromagnetic radiation with substance in which dominating mechanisms are allocated lay. It allows to simplify essentially the decision of inverse problems and to use fast algorithms of their realization. Focusing of radiation is carried out with use of mirrors, lenses, and also methods of 3-D coordinated filtrations with regularization. The examples confirming working capacity of a method for without contact tomography of structure of a forest, detection and visualization landmines hidden under a rough surface of sand are resulted. The description of the developed experimental installations is given. It is shown, that using of UWB radiation allows raising considerably accuracy of measurements at preservation of a real time scale of data processing.

Yakubov, V. P.; Telpuchovski, E. D.; Zepelev, G. M.; Klokov, A. V.; Moiseenko, N. A.; Novik, S. N.; Suhanov, D. Ya.; Yakubova, O. V.

2006-11-01

307

Development of optical field emitter arrays  

E-print Network

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

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

2013-01-01

308

Rain radars for earth science geostationary platforms: Some possibilities  

NASA Technical Reports Server (NTRS)

Results of a feasibility study for a geostationary rain radar are presented. A 2-cm wavelength radar with a 15 to 20 mm antenna will be useful for general scale meteorology. The transmitter power of 500 W with a pulse compression ratio of 200 will provide adequate signal-to-noise ratio for a rain rate of 1 mm/hour. Various problems associated with a geostationary radar and solutions are also discussed.

Gogineni, S. P.; Moore, R. K.

1989-01-01

309

Adaptive MIMO Radar for Target Detection, Estimation, and Tracking  

Microsoft Academic Search

We develop and analyze signal processing algorithms to detect, estimate, and track targets using multiple-input multiple-output (MIMO) radar systems. MIMO radar systems have attracted much attention in the recent past due to the additional degrees of freedom they offer. They are commonly used in two different antenna configurations: widely-separated (distributed) and colocated. Distributed MIMO radar exploits spatial diversity by utilizing

Sandeep Gogineni

2012-01-01

310

Spatial-Temporal-Frequency Diversity in Radar Sensor Networks  

Microsoft Academic Search

In this paper, the spatial-temporal-frequency diversity to improve the detection performance of Radar Sensor Networks (RSN) in the presence of certain types of interference (clutter, jamming, noise and interference between radar sensors) is studied. In order to reduce the interference between radar sensors and maximize the signal-to-interference-plus-noise ratio (SINR), we propose a method using the orthogonality criterion to design waveforms

Hung D. Ly; Qilian Liang

2006-01-01

311

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

312

Thermal spray approach for TPV emitters  

Microsoft Academic Search

We have fabricated selective emitters and systematically investigated their performance in comparison with a gray body (SiC-based composite) emitter. The two key elements of our approach are (1) using thermal-spraying to manufacture thin-film selective emitters, and (2) exploring a variety of oxide materials, including rare-earths (erbia, thulia, and holmia) and cobalt-doped spinel. We fabricated the emitters by plasma-spraying coatings at

Christopher J. Crowley; Nabil A. Elkouh; Patrick J. Magari

1999-01-01

313

Radar backscatter modelling  

NASA Technical Reports Server (NTRS)

The terrain analysis software package was restructured and documentation was added. A program was written to test Johnson Space Center's four band scatterometer data for spurious signals data. A catalog of terrain roughness statistics and calibrated four frequency multipolarization scatterometer data is being published to support the maintenance of Death Valley as a radar backscatter calibration test site for all future airborne and spacecraft missions. Test pits were dug through sand covered terrains in the Eastern Sahara to define the depth and character of subsurface interfaces responsible for either backscatter or specular response in SIR-A imagery. Blocky sandstone bedrock surfaces at about 1 m depth were responsible for the brightest SIR-A returns. Irregular very dense CaCO3 cemented sand interfaces were responsible for intermediate grey tones. Ancient river valleys had the weakest response. Reexamination of SEASAT l-band imagery of U.S. deserts continues.

Schaber, G. G.; Kozak, R. C.; Gurule, R. L.

1984-01-01

314

Multifrequency space time orthogonal projection (MF-STOP): a radar signal processing algorithm for detecting and discriminating targets in heavy clutter  

NASA Astrophysics Data System (ADS)

In this paper, we present a Multi-Frequency Space-Time Orthogonal (MF-STOP) adaptive filtering approach for detection and discrimination of targets based on a two stage orthogonal projection whereby target parameters can be extracted in the presence of heavy clutter and noise. The proposed technique detects targets within heavy clutter tracked by a radar system. After targets are detected, motion information is extracted that can be used to discriminate threats such as reentry vehicles from other targets. Target detection is generated in stage one by a combination of Windowed Short Time Fast Fourier Transform (WSTFFT) processing and Principal Component Analysis (PCA). Target discrimination is done in a second stage via Partial Least Squares (PLS) using a training filter constructed from the stage one detection. The target is discriminated explicitly by metric criteria such as size or precession. These discriminate features do not have to be known a priori.

Tamrat, Yalew; Hatleberg, Clancy

2007-04-01

315

Remorque RADAR Description technique  

E-print Network

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

Heurteaux, Yanick

316

The MU radar  

NASA Astrophysics Data System (ADS)

The middle atmosphere (stratosphere, mesosphere, and lower thermosphere) is now being studied intensively. Mesosphere-stratosphere-troposphere (MST) radars are playing a vital role in observing middle atmospheric motions. These radars receive very weak echoes caused by scattering from atmospheric density fluctuations that are produced by clear air turbulence. These irregularities move with the local wind so that the Doppler shift of the radar echo power spectrum gives the component of the local wind along the line of sight of the radar beam.

Kato, S.

317

A newsletter for non-scientists (and scientists) interested in MAGIC Radars transmit pulses of radio waves of a given frequency and receive signals that are  

E-print Network

pulses of radio waves of a given frequency and receive signals that are reflected, or scattered, from of the returned signal, the distance to the objects and information about their properties can be determined sizes of raindrops. The Doppler effect pertains to the change in frequency of a wave emitted

318

Lunar radar backscatter studies  

NASA Technical Reports Server (NTRS)

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

Thompson, T. W.

1979-01-01

319

Radar hydrology: rainfall estimation  

Microsoft Academic Search

Radar observations of rainfall and their use in hydrologic research provide the focus for the paper. Radar-rainfall products are crucial for input to runoff and flood prediction models, validation of satellite remote sensing algorithms, and for statistical characterization of extreme rainfall frequency. In this context we discuss the issues of radar-rainfall product development, and the theoretical and practical requirements of

W. F. Krajewski; J. A. Smith

2002-01-01

320

Netted radar sensing  

Microsoft Academic Search

In this paper we consider a number of aspects illustrating how networks of radar sensor systems (rather than a single monostatic radar) can offer a counter to stealth technology whilst simultaneously providing more detailed information for improved target detection, classification and location. The netted radar equation is developed, coverage, detection and location performance are quantified, and the potential utility of

A. L. Hume; C. J. Baker

2001-01-01

321

Chemically Etched Open Tubular and Monolithic Emitters for Nanoelectrospray Ionization Mass Spectrometry  

PubMed Central

We have developed a new procedure for fabricating fused silica emitters for electrospray ionization-mass spectrometry (ESI-MS) in which the end of a bare fused silica capillary is immersed into aqueous hydrofluoric acid, and water is pumped through the capillary to prevent etching of the interior. Surface tension causes the etchant to climb the capillary exterior, and the etch rate in the resulting meniscus decreases as a function of distance from the bulk solution. Etching continues until the silica touching the hydrofluoric acid reservoir is completely removed, essentially stopping the etch process. The resulting emitters have no internal taper, making them much less prone to clogging compared to e.g. pulled emitters. The high aspect ratios and extremely thin walls at the orifice facilitate very low flow rate operation; stable ESI-MS signals were obtained for model analytes from 5-?m-diameter emitters at a flow rate of 5 nL/min with a high degree of inter-emitter reproducibility. In extensive evaluation, the etched emitters were found to enable approximately four times as many LC-MS analyses of proteomic samples before failing compared with conventional pulled emitters. The fabrication procedure was also employed to taper the ends of polymer monolith-containing silica capillaries for use as ESI emitters. In contrast to previous work, the monolithic material protrudes beyond the fused silica capillaries, improving the monolith-assisted electrospray process. PMID:17105173

Kelly, Ryan T.; Page, Jason S.; Luo, Quanzhou; Moore, Ronald J.; Orton, Daniel J.; Tang, Keqi; Smith, Richard D.

2007-01-01

322

Active cancellation stealth analysis of warship for LFM radar  

Microsoft Academic Search

Active stealth of warship is an important developing direction in modern stealth technology field. Based on scattering properties of warship and characteristics of linear frequency modulated (LFM) signal and its matched filter, the cancellation signal was designed. Warship stealth was achieved through interference cancellation between cancellation signal and radar echo signal. Simulation results show that complete stealth of warship can

Ying-chun Xiang; Chang-wen Qu; Feng Su; Ming-jun Yang

2010-01-01

323

Using radar sea echo to estimate surface layer refractivity profiles  

Microsoft Academic Search

A method for inferring the atmospheric boundary layer evaporation duct height from sea clutter is described. The method is based on the observation that the radar signal from the evaporation duct manifests itself in the slope of the clutter power, while the horizontal variability of the sea clutter RCS (radar cross section) is a contaminant in the problem. The inversion

L. Ted ROgersl; Claude P. Hattan; Jeffery L. Krolik

1999-01-01

324

Vertical Radar Profiles for the Characterization of Deep Vadose Zones  

Microsoft Academic Search

characteristics of radar signal propagation along differ- ent directions in the subsurface. The deep vadose zone, down to a few tens of meters below the The most common application of radar for hydrologic soil surface, is difficult to investigate and characterize, especially from mediation, with the aim of characterizing the dynamic hydrologic be- havior of the deep vadose zone. We

Giorgio Cassiani; Claudio Strobbia; Laura Gallotti

2004-01-01

325

Countering stealth with passive, multi-static, low frequency radars  

Microsoft Academic Search

The potential of passive, multi-static radars as covert sensors for the detection of low flying, stealth air targets are illustrated by multi-static RCS analysis, coverage simulations for low flight levels and measurement results obtained with an experimental passive radar using digital audio broadcast signals (DAB). The measurement sensor is described and future perspectives are pointed out.

H. Kuschel; J. Heckenbach; S. Mu?ller; R. Appel

2010-01-01

326

Computer generation of correlated non-Gaussian radar clutter  

Microsoft Academic Search

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

Muralidhar Rangaswamy; Donald Weiner; Aydin Ozturk

1995-01-01

327

Remote Sensing of Hail with a Dual Linear Polarization Radar  

Microsoft Academic Search

A technique for the remote sensing of hail with an S-band dual linear polarization radar is described. The method employs a new hail signal HDR, which is derived from disdrometer measurements of raindrop size distributions. Experimental measurements, made in Colorado with the National Center for Atmospheric Research's (NCAR) CP-2 radar system, are used to demonstrate the technique in two major

K. Aydin; T. A. Seliga; V. Balaji

1986-01-01

328

Space-time adaptive processing for airborne radar  

Microsoft Academic Search

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

James Ward

1994-01-01

329

Synchronization for wireless multi-radar covert communication networks  

Microsoft Academic Search

The motivation for our current work is the need for a covert wireless communication network between multi-site radars. Such radars form an effective network-centric architecture that has intrinsic properties such as LPI, LPD, and good data dissemination capabilities. Our continuing work indicates that a notched UWB noise signal within which OFDM data symbols are embedded can be used as a

Shrawan C. Surender; Ram M. Narayanan

2007-01-01

330

ECCM capabilities of an ultrawideband bandlimited random noise imaging radar  

Microsoft Academic Search

Investigated here is high-resolution imaging of targets in noisy or unfriendly radar environments through a simulation analysis of the ultrawideband (UWB) continuous-wave (CW) bandlimited random noise waveform. The linear FM chirp signal was selected as a benchmark radar waveform for comparison purposes. Simulation of the recovery of various types of target reflectivity functions (TRFs) for these waveforms were performed and

DMITRIY S. GARMATYUK; RAM M. NARAYANAN

2002-01-01

331

NONLINEARITY CORRECTION ALGORITHM FOR WIDEBAND FMCW RADARS Andrei Anghel  

E-print Network

NONLINEARITY CORRECTION ALGORITHM FOR WIDEBAND FMCW RADARS Andrei Anghel Gabriel Vasile Remus- rithm for wideband frequency modulated continuous wave (FMCW) radars based on high-order ambiguity functions (HAF) and time resampling. By emphasizing the polynomial- phase nature of the FMCW signal

Paris-Sud XI, Université de

332

Radar Meteorology Tutorial  

NSDL National Science Digital Library

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

McNoldy, Brian

333

Target spatial and frequency scattering diversity property for diversity MIMO radar  

Microsoft Academic Search

Statistical multiple-input multiple-output (MIMO) radar, e.g., frequency diversity MIMO radar (FDMR) and spatial diversity MIMO radar (SDMR), can exploit signal diversity to improve target detection performance. The statistical property of target echo signals received in diversity channels is an important concern in designing signal processing algorithms for an FDMR and an SDMR, which is studied in this paper by using

Shenghua Zhou; Hongwei Liu; Yongbo Zhao; Liangbing Hu

2011-01-01

334

Stepped frequency ground penetrating radar  

DOEpatents

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

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

1994-01-01

335

Wire scanner data analysis for the SSC Linac emittance measurement  

SciTech Connect

The wire scanners are designed in the SSC Linac for measurement of beam emittance at various locations. In order to obtain beam parameters from the scan signal, a data analysis program was developed that considers the problems of noise reduction, machine modeling, parameter fitting, and correction. This program is intended as a tool for Linac commissioning and also as part of the Linac control program. Some of the results from commissioning runs are presented.

Yao, C.Y.; Hurd, J.W.; Sage, J.

1993-07-01

336

Nonlocality from N>2 independent single-photon emitters  

SciTech Connect

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

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

2010-09-15

337

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

E-print Network

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

Paris-Sud XI, Université de

338

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

E-print Network

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

Boyer, Edmond

339

Near field focusing algorithm for high frequency ground penetration imaging radar  

Microsoft Academic Search

Ground penetrating radar has been successfully used for imaging stratigraphic structures. The goal of our ground penetrating radar program is to provide a capability for strategic subsurface target detection for military applications. This paper describes an experimental approach to high frequency (HF) radar sub-surface profiling, and the results obtained from signal and data processing for deep tunnel detection. Ongoing experiments

Russell D. Brown; E. Douglas Lynch; David W. Mokry; James M. VanDamme; Richard A. Schneible; Michael C. Wicks

1999-01-01

340

X-band Radar System for Detecting Heart and Respiration Rates  

E-print Network

X-band Radar System for Detecting Heart and Respiration Rates Jee-Hoon Lee, Yun-Taek Im, and Seong an X-band Doppler radar system to detect heart and respiration of human far away. Through the idea polarization. This bistatic radar system can be used in non-invasively sensing bio signals such as respiration

Park, Seong-Ook

341

Present State and Ways of Passive Anti-LPI Radar Implementation  

Microsoft Academic Search

Radar of small range with Low Probability of Intercept (LPI radar) and means of secure communications of noise and quasi noise type attract now attention of engineers. Some examples of LPI radar were presented The emission stealth can be provided by using noise type signals with large time-bandwidth product. However, one should take into account the limited stealth capabilities of

Y. D. Shirman; V. M. Orlenko; S. V. Seleznev

2006-01-01

342

3-d simulations for radar cross-section reduction using plasma absorbers  

Microsoft Academic Search

Summary form only given. Radar cross section (RCS) is the measure of a target's ability to reflect radar signals in the direction of the radar receiver. A collisional unmagnetized plasma, surrounding the target, acts as a good absorber of electromagnetic waves over a wide frequency range, reducing its RCS. This has given rise to world wide interest in plasma stealth

B. Chaudhury; S. Chaturvedi

2006-01-01

343

DIVERSE RADAR PULSE-TRAIN WITH FAVOURABLE AUTOCORRELATION AND AMBIGUITY E. Mozeson and N. Levanon  

E-print Network

DIVERSE RADAR PULSE-TRAIN WITH FAVOURABLE AUTOCORRELATION AND AMBIGUITY FUNCTIONS E. Mozeson and N radar signal, mainly due to its good range and Doppler resolution. One of its drawbacks fundamental limitations on the ability of any radar waveform of constrained time-bandwidth product

Levanon, Nadav

344

Impact crater related surficial deposits on Venus: Multipolarization radar observations with Arecibo  

Microsoft Academic Search

The distribution of surficial deposits in the vicinity of impact craters on Venus was studied using measurements of the polarization properties of the reflected radar wave. Subsurface scattering of an incident circularly polarized radar signal results in a linearly polarized component in the radar echo due to the differing transmission coefficients at a smooth (at wavelength scales) atmosphere-surface boundary for

Lynn M. Carter; Donald B. Campbell; Bruce A. Campbell

2004-01-01

345

Robust radar detection of GMTI targets with STAP D. M. Carrington and Dr. P. G. Kealey  

E-print Network

Robust radar detection of GMTI targets with STAP D. M. Carrington and Dr. P. G. Kealey Qineti. Introduction. Ground Moving Target Indication (GMTI) radar is able to detect moving targets using short dwell times by distinguishing the weak radar signal of the moving target from the dominant returns due

Haddadi, Hamed

346

Region-Enhanced Imaging for Sparse-Aperture Passive Radar Mujdat Cetina and Aaron D. Lantermanb  

E-print Network

goal in passive radar imaging is to form images of aircraft using signals transmitted by commercial. Such passive multistatic radar systems have been developed to detect and track aircraft. If one couldRegion-Enhanced Imaging for Sparse-Aperture Passive Radar M¨ujdat C¸etina and Aaron D. Lantermanb a

?etin, Müjdat

347

Sense-Through-Wall Human Detection Using UWB Radar With Sparse SVD  

E-print Network

-Through-Wall Human Detection Using UWB Radar With Sparse SVD Xiaoyang Lia , Qilian Liangb , Francis C.M. Laua, Singular Value Decomposition, Lanczos Process 1. Introduction UWB radars are used nowadays for different the highest and lowest frequencies of interest and con- tains about 95% of the signal power [2][3]. Such radar

Lau, Francis C.M.

348

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

E-print Network

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

349

Automatic identification of bird targets with radar via patterns produced by  

E-print Network

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

Loon, E. Emiel van

350

Multi-frequency fine resolution imaging radar instrumentation and data acquisition. [side-looking radar for airborne imagery  

NASA Technical Reports Server (NTRS)

Development of a dual polarized L-band radar imaging system to be used in conjunction with the present dual polarized X-band radar is described. The technique used called for heterodyning the transmitted frequency from X-band to L-band and again heterodyning the received L-band signals back to X-band for amplification, detection, and recording.

Rendleman, R. A.; Champagne, E. B.; Ferris, J. E.; Liskow, C. L.; Marks, J. M.; Salmer, R. J.

1974-01-01

351

Development and characterization analysis of a radar polarimeter  

E-print Network

of components shown in the block diagram of Figure 10. The microwave source that is used in each radar head corresponds to the frequency operation of the particular radar head. The RF head sub-assembly serves the purpose of generating signals that have been... System The operational block diagram of a FMCW radar system is presented in Figure 2a. Figure 2b illustrates the operation of an FMCW Radar System. The RF frequency is modulated over a bandwidth af at a rate of fm. For a point target, the time domain...

Bong, Soei Siang

1984-01-01

352

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 500C.

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

2014-03-01

353

A lightweight ground penetrating radar  

SciTech Connect

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

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

1998-12-31

354

Two terminal micropower radar sensor  

DOEpatents

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

McEwan, Thomas E. (Livermore, CA)

1995-01-01

355

Two terminal micropower radar sensor  

DOEpatents

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

McEwan, T.E.

1995-11-07

356

Combustion powered thermophotovoltaic emitter system  

SciTech Connect

The United States Naval Academy, under interagency agreement with the Department of Energy (DOE), has recently completed an engineering design project for a high temperature thermophotovoltaic (TPV) photon emitter. The design was constrained by the physical geometry and photovoltaic cell type of the DOE TPV generator so that a cylindrical emitter at 1,756 K (2,700 F) was dictated. 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 DOE requirements. This paper outlines the engineering design process, discusses obstacles and solutions encountered, and presents the final design. The concept of thermophotovoltaic energy conversion dates to the 1960s and has been the subject of broad research effort. This is a direct energy conversion process that converts thermal energy into electricity with only photonic coupling. The process offers high theoretical efficiency, versatile application as a primary or secondary power cycle, and a number of operational advantages resulting from the lack of a working substance or moving parts.

McHenry, R.S.; Harper, M.J.; Lindler, K.W. [Naval Academy, Annapolis, MD (United States). Naval Architecture, Ocean and Marine Engineering

1995-12-31

357

Alpha particle emitters in medicine  

SciTech Connect

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

Fisher, D.R.

1989-09-01

358

Wideband radar micro-doppler applications  

NASA Astrophysics Data System (ADS)

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

Tahmoush, Dave

2013-05-01

359

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

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

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

360

Radar systems for a polar mission, volume 1  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

361

Development of a Low-Cost UAV Doppler Radar Data System  

NASA Technical Reports Server (NTRS)

A viewgraph presentation on the design of a low cost unmanned aerial vehicle (UAV) doppler radar data system is presented. The topics include: 1) Science and Mission Background; 2) Radar Requirements and Specs; 3) Radar Realization: RF System; 4) Processing of RF Signal; 5) Data System Design Process; 6) Can We Remove the DSP? 7) Determining Approximate Speed Requirements; 8) Radar Realization: Data System; 9) Data System Operation; and 10) Results.

Knuble, Joseph; Li, Lihua; Heymsfield, Gerry

2005-01-01

362

Diversity in Radar Sensor Networks: Theoretical Analysis and Application to Target Detection  

Microsoft Academic Search

We study a diversity scheme based on waveform design and space-time adaptive processing to improve the detection performance\\u000a of radar sensor networks in the presence of certain types of interference. To reduce the interference between radar sensors\\u000a and maximize the signal-to-interference-plus-noise ratio, we use an orthogonality criterion to design waveforms for radar\\u000a sensors. Besides, performance of radar sensor networks depends

Hung D. Ly; Qilian Liang

2009-01-01

363

A planar hybrid transceiving mixer at 76.5 GHz for automotive radar applications  

Microsoft Academic Search

A growing number of applications for radar systems in automobiles demands for low-cost radar front-ends. A planar monostatic radar front-end is particularly suited for low cost applications as it uses only one antenna for transmission and reception and, thus, minimizes the needed chip area. Generally, in a standard homodyne radar a radio-frequency (RF) signal generated by an oscillator is used

M. O. Olbrich; A. Grbl; R. H. Rahofer; E. M. Biebl

2003-01-01

364

The Urbana MST radar, capabilities and limitations  

NASA Technical Reports Server (NTRS)

The 41-MHz coherent-scatter radar located northeast of the University of Illinois at Urbana is being used for studies of the troposphere, stratosphere and mesosphere regions. The antenna consists of 1008 halfwave dipoles with a physical aperture of 11000 sq m. Transmitted peak power is about 750 kW. Clear-air returns may be received from 6 km to 90 km altitude. Autocorrelation functions of the scattered signal are calculated on-line. From the autocorrelation functions the scattered power, line-of-sight velocity and signal correlation time are calculated. Some aspects of the troposphere/stratosphere and the mesosphere observations are discussed. Capabilities and limitations of the Urbana MST radar are pointed out, and recent and planned improvements to the radar are described.

Royrvik, O.; Goss, L. D.

1983-01-01

365

Interpretation of radar returns from clear air: Discrimination against clutter  

NASA Technical Reports Server (NTRS)

Different kinds of inteference may cause problems to the proper detection and analysis of the atmospheric signals, when using VHF and UHF radars. These are separated into passive and active contributions. Passive contributions are existent in the receiving system without the radar transmitter switched on. Active contributions are due to scatter and reflection of the own transmitted radar signal from unwanted targets, which are called clutter. Of major importance to radar systems are active interference contributions. Different methods can be applied for elimination or at least suppressing unwanted effects. These are; (1) Directional filtering, i.e., applying optimum suppression of antenna sidelobes, (2) Range filtering, i.e., suppressing unwanted signals only in affected range gates, (3) selection by amplitude distributions, (4) Temporal filtering, i.e., recognizing typical temporal variations of the clutter signals, through spectral characteristics, and applying matched filters.

Rottger, J.

1983-01-01

366

Radar Imaging Systems Joseph Charpentier  

E-print Network

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

367

LPI radar: fact or fiction  

Microsoft Academic Search

LPI radar is a system that consists of a radar and ES system. Its performance depends on both components. An LPI performance factor is derived and applied to several examples. Operational LPI radars are described. A digital LPI radar detector is described and test results presented. A recent book on LPI radar received a number of somewhat critical reviews that

D. C. Schleher

2006-01-01

368

Locating RF Emitters with Large UAV Teams Paul Scerri, Robin Glinton, Sean Owens and Katia Sycara  

E-print Network

Locating RF Emitters with Large UAV Teams Paul Scerri, Robin Glinton, Sean Owens and Katia Sycara efficient way for a team of UAVs with Received Signal Strength Indicator (RSSI) sen- sors to locate radio locations requires integrating multiple signals from different UAVs into a Bayesian filter, hence requir

Scerri, Paul

369

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

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

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

370

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

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

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

371

Ultrafast oscilloscope based on laser-triggered field emitters.  

PubMed

Laser-triggered electron emission from sharp metal tips has been demonstrated in recent years as a high brightness, ultrafast electron source. Its possible applications range from ultrafast electron microscopy to laser-based particle accelerators to electron interferometry. The ultrafast nature of the emission process allows for the sampling of an instantaneous radio frequency (RF) voltage that has been applied to a field emitter. For proof-of-concept, we use an RF signal derived from our laser's repetition rate, mapping a 9.28 GHz signal in 22.4 fs steps with 28 mv accuracy. PMID:25679859

Kealhofer, Catherine; Klopfer, Brannon B; Skulason, Gunnar E; Juffmann, Thomas; Foreman, Seth M; Kasevich, Mark A

2015-01-15

372

Application of arbitrary waveform generator for noise radar  

Microsoft Academic Search

The approach, when the waveforms of different types are exploited in the same radar (waveform diversity) requires new-generation sources of initial signals. For generating of different types of waveforms in the same radar we suggest using Arbitrary Waveform Generator, that allows output any type of pre-programmed signal in real time. We have carried out preliminary experimental tests of the stepped-delay

Konstantin A. Lukin; Oleg V. Zemlyaniy; Pavlo L. Vyplavin; Volodymyr P. Palamarchuk

2011-01-01

373

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

374

Emittance measurements of RCG coated Shuttle tiles  

NASA Technical Reports Server (NTRS)

The spectral and total normal emittance of the Reaction Cured Glass (RCG) coating used on Shuttle tiles has been measured for surface temperatures of 300 to 1905 K. These measurements were made on two virgin and two flown Shuttle tile samples. Room temperature directional emittance data were also obtained and used to determine the total hemispherical emittance of RCG as a function of temperature. The data obtained from this calculation indicate that the total hemispherical emittance decreases from a room temperature value of 0.83 to a value of 0.76 at 1905 K. The flown Shuttle tiles exhibited a change in the spectral distribution of emittance compared to that of the virgin tile, but no significant trends in the total emittance from a virgin to a flown tile could be established.

Bouslog, Stanley A.; Cunnington, George R., Jr.

1992-01-01

375

Planetary radar studies  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

376

Laser radar in robotics  

SciTech Connect

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

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

1996-02-01

377

Radar in transition  

NASA Astrophysics Data System (ADS)

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

Barton, D. K.

1984-12-01

378

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

E-print Network

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

Vaidyanathan, P. P.

379

Sea and ground radar clutter modeling  

Microsoft Academic Search

The modeling of the clutter echoes is a central issue for the design and performance evaluation of radar systems. The aim of this paper is to describe the state-of-the-art approaches to the modeling and understanding of land and sea clutter echoes and their implications on performance prediction and signal processors design. The tutorial is mainly divided in 5 parts: (i)

M. W. Long; M. S. Greco

2008-01-01

380

Radar observations of F region equatorial irregularities  

Microsoft Academic Search

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

Ronald F. Woodman; Csar La Hoz

1976-01-01

381

Radars. Volume 6 - Frequency agility and diversity  

Microsoft Academic Search

Radar frequency diversity techniques, which reduce measurement errors caused by target glint, amplitude modulation and multipath, are discussed. Attention is given to frequency diversity attained through use of two or more parallel transmitting and receiving channels, or through the sequential use of many frequencies. Topics of the papers include a sequential detection logic to improve signal detectability in frequency-agile search

D. K. Barton

1977-01-01

382

A polarization diversity meteorological radar system  

Microsoft Academic Search

The AFGL 10-cm Doppler weather radar was modified to enable the measurement of the differential reflectivity between horizontal and vertical polarizations in addition to the absolute reflectivity and the Doppler mean velocity and spectrum variance. Polarization switching is achieved by means of a diplexer, which separates at the antenna the transmitted signals of two frequencies, 2710 and 2760 MHz, and

James I. Metcalf; Graham M. Armstrong; Alexander W. Bishop

1987-01-01

383

Integrated bias removal in passive radar systems  

Microsoft Academic Search

A passive coherent location (PCL) system exploits the ambient FM radio or television signals from powerful local transmitters, which makes it ideal for covert tracking. In a passive radar system, also known as PCL system, a variety of measurements can be used to estimate target states such as direction of arrival (DOA), time difference of arrival (TDOA) or Doppler shift.

M. Subramaniam; K. Punithakumar; M. McDonald; T. Kirubarajan

2008-01-01

384

Quantification of Reflection Patterns in Ground-Penetrating Radar Data  

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

385

Caribbean Radar Cases  

NSDL National Science Digital Library

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

COMET

2013-12-31

386

Silence tracking radar  

Microsoft Academic Search

A high performance linear FMCW radar sensor and its implementation as tracking radar are presented. The radar has been built with an all-solid state transmitter with 200 mw output power and two channel receivers with 9 dB noise figure. Tracking range of more than 10 km, angle error of better than 0.5 mrad and range error of better than 5

Zhang Guanjie; Guo Min; Bao Yongjie

2001-01-01

387

Aircraft radar echoes characterization  

NASA Astrophysics Data System (ADS)

Electromagnetic wave diffraction and reflection theories enable prediction of most of the effects generated by radar echoes on aircraft. However, it is difficult to modelize some complex effects originating in canopies, radomes and cavities. In order to supplement the present theoretical knowledge by experimental results obtained on actual targets, ONERA has developed a novel analysis method allowing the generation of radar images. This method provides an efficient working tool to assist in defining radar wise discrete aerial targets.

Pouit, C.

1980-04-01

388

Fiber optic relayed laser radar  

NASA Astrophysics Data System (ADS)

We present a new ladar (laser radar) for the detection of objects off the line-of-sight. This is accomplished by a transceiver and a fiberoptic cable that relays an outgoing laser beam to, and a returning signal from a target. The transmission signal is a laser diode emitted beam at 1550 nm, ideal from the aspects of both eyesafety and minimum loss in a silica fiber. In our immediate application, the detection of an obstacle on the railroad track of a high-speed train, the laser pulses propagate through air and the fiberoptic cable, successively. Under a variety of simulated weather conditions and by traversing twice through a 2 km fiber, we measured a signal-to-noise of 300.

Tilleman, Michael M.; Oakes, David B.; Krishnaswami, Kannan

1995-08-01

389

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

390

The Invisible Radar Triangle  

NSDL National Science Digital Library

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

RET-ENET Program, Electrical Engineering Department,

391

On the design of optimum radar waveforms for clutter rejection  

Microsoft Academic Search

The problem to be considered in this paper is that of designing radar signals and receivers that are optimum for detecting a point target masked by a background of clutter returns and thermal noise. The problem of choosing an optimum signal when no constraints are placed on the type of signals allowed is discussed briefly, but the remainder of the

D. DeLong; E. Hofstetter

1967-01-01

392

Generalized radar/radiometry imaging problems  

E-print Network

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

Genève, Université de

393

Research on Atmospheric Disturbance Correction method of ground-based radar interferometry  

NASA Astrophysics Data System (ADS)

The high-frequency signal is often used as the communication signal of Ground-based radar, which is susceptible to atmospheric effects. An atmospheric disturbance correction of radar signal is required to obtain the monitoring accuracy of better than millimeter in precision deformation monitoring using ground-based radar interferometry. In this paper, we analyzed the experimental-data change of ground-based radar in the atmospheric disturbance statistically and proposed a correction method based on the discrete stable point in the global environment. The following experiment proved that this method can optimize the measurement results for the scene of small-scale.

Zhou, X.; Xu, Y. M.; Wang, P.; Xing, C.

2014-03-01

394

High-resolution three-dimensional imaging radar  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

395

Considerations on data compression of synthetic aperture radar images  

NASA Technical Reports Server (NTRS)

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

Wu, C.

1976-01-01

396

Goldstone Solar System Radar Waveform Generator  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

397

SMAP Radar Processing and Expected Performance  

NASA Astrophysics Data System (ADS)

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

West, R. D.; Jaruwatanadilok, S.

2011-12-01

398

Decoders for MST radars  

NASA Technical Reports Server (NTRS)

Decoding techniques and equipment used by MST radars are described and some recommendations for new systems are presented. Decoding can be done either by software in special-purpose (array processors, etc.) or general-purpose computers or in specially designed digital decoders. Both software and hardware decoders are discussed and the special case of decoding for bistatic radars is examined.

Woodman, R. F.

1983-01-01

399

The Cloud Radar System  

NASA Technical Reports Server (NTRS)

Improvement in our understanding of the radiative impact of clouds on the climate system requires a comprehensive view of clouds including their physical dimensions, dynamical generation processes, and detailed microphysical properties. To this end, millimeter vave radar is a powerful tool by which clouds can be remotely sensed. The NASA Goddard Space Flight Center has developed the Cloud Radar System (CRS). CRS is a highly sensitive 94 GHz (W-band) pulsed-Doppler polarimetric radar that is designed to fly on board the NASA high-altitude ER-2 aircraft. The instrument is currently the only millimeter wave radar capable of cloud and precipitation measurements from above most all clouds. Because it operates from high-altitude, the CRS provides a unique measurement perspective for cirrus cloud studies. The CRS emulates a satellite view of clouds and precipitation systems thus providing valuable measurements for the implementation and algorithm validation for the upcoming NASA CloudSat mission that is designed to measure ice cloud distributions on the global scale using a spaceborne 94 GHz radar. This paper describes the CRS instrument and preliminary data from the recent Cirrus Regional Study of Tropical Anvils and Cirrus Layers - Florida Area Cirrus Experiment (CRYSTAL-FACE). The radar design is discussed. Characteristics of the radar are given. A block diagram illustrating functional components of the radar is shown. The performance of the CRS during the CRYSTAL-FACE campaign is discussed.

Racette, Paul; Heymsfield, Gerald; Li, Lihua; Tian, Lin; Zenker, Ed

2003-01-01

400

Radars for the eighties  

Microsoft Academic Search

The Modular Survivable Radar (MSR), proposed by the General Electric Company as the solution to the USAF's airborne attack radar requirements, is a flexible system with ECCM and low probability of intercept (LPI) protection capabilities. The system is built with standard modular line replaceable units (LRU) and is adaptable to a wide range of performance requirements. The structure of the

M. Shohat

1979-01-01

401

Netted radar sensing  

Microsoft Academic Search

We consider how networks of radar sensors can offer a counter to stealth technology whilst simultaneously providing more detailed information for improved target classification. Specifically, it is shown how multiple independent sensors can provide an energetically more efficient collector of radar scatter. Further, the relative merits of non-coherent and coherent dependent networks are discussed particularly emphasising the balance between increased

A. L. Hume; C. J. Baker

2001-01-01

402

Aircraft radar antennas  

Microsoft Academic Search

Many changes have taken place in airborne radar antennas since their beginnings over forty years ago. A brief historical review of the advances in technology is presented, from mechanically scanned reflectors to modern multiple function phased arrays. However, emphasis is not on history but on the state-of-the-art technology and trends for future airborne radar systems. The status of rotating surveillance

Helmut E. Schrank

1987-01-01

403

Java Radar Analysis Tool  

NASA Technical Reports Server (NTRS)

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

Zaczek, Mariusz P.

2005-01-01

404

Radar illusion via metamaterials  

NASA Astrophysics Data System (ADS)

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

Jiang, Wei Xiang; Cui, Tie Jun

2011-02-01

405

Porous silicon field emitters for display applications  

Microsoft Academic Search

A fabrication technology for porous silicon (PS) field emitters for display applications is described. Silicon blunt emitters prepared on p-type silicon wafers of 30 ? cm resistivity were covered with a thin layer of porous silicon using an electrochemical anodization in ethanoic hydrofluoric solution. A PS layer with similar characteristics was also prepared on flat silicon surfaces. The PS layer

I. Kleps; D. Nicolaescu; C. Lungu; G. Musa; C. Bostan; F. Caccavale

1997-01-01

406

Determining Directional Emittance With An Infrared Imager  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

407

Selective Emitter Pumped Rare Earth Laser  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

408

Looking at Radar Images  

NSDL National Science Digital Library

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

409

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

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

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

410

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

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

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

411

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

E-print Network

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

Stoffelen, Ad

412

Radar sensor for remote control of track occupancy and railway cars speed  

Microsoft Academic Search

The results of development of low cost radar sensors for remote control of track occupancy and railway cars' speed over the territory of hump yards under heavy weather conditions are presented. The radar sensor feature is application of autodyne transmitting-receiving module for linear frequency modulation and digital systems for forming sounding signal and spectral processing of received signals. Sensor is

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

2009-01-01

413

Low probability of intercept (LPI) techniques and implementations for radar systems  

Microsoft Academic Search

After a brief overview of optimal low-probability of intercept (LPI) radar design criteria, it is shown that for a given radar signal code length, many more codes are available by using higher-order Galois fields; that is, polyphase coding will supply the required diversity. Various aspects of polyphase coding are described because Doppler compensation of the returned signal is a polyphase

E. J. Carlson

1988-01-01

414

Tracking radar with LPI characteristics based on high rate SS-FH  

Microsoft Academic Search

A new signal modulation format used for a tracking radar showing very low probability of detection and interception is proposed. The radar working principle is based on the application of spread spectrum-frequency hopping technique. The surveillance is done radiating a very low power microwave signal during very short pulses spread randomly over a large bandwidth dramatically reducing the radiated energy.

J. Sanmartin-Jara; J. Burgos-Garcia; J. Cuesta-Acosta; F. Perez-Martinez

1999-01-01

415

Region-enhanced passive radar imaging M. C etin and A.D. Lanterman  

E-print Network

signals transmitted by commercial radio and television stations that are reflected from the objects to the problem of passive radar imaging. One goal in passive radar imaging is to form images of aircraft using by measuring and analysing the reflected signals. (Ground- based systems looking at airborne targets

Yanikoglu, Berrin

416

Description and availability of airborne Doppler radar data  

NASA Technical Reports Server (NTRS)

An airborne, forward-looking, pulse, Doppler radar has been developed in conjunction with the joint FAA/NASA Wind Shear Program. This radar represents a first in an emerging technology. The radar was developed to assess the applicability of an airborne radar to detect low altitude hazardous wind shears for civil aviation applications. Such a radar must be capable of looking down into the ground clutter environment and extracting wind estimates from relatively low reflectivity weather targets. These weather targets often have reflectivities several orders of magnitude lower than the surrounding ground clutter. The NASA radar design incorporates numerous technological and engineering achievements in order to accomplish this task. The basic R/T unit evolved from a standard Collins 708 weather radar, which supports specific pulse widths of 1-7 microns and Pulse Repetition Frequencies (PRF) of less than 1-10 kHz. It was modified to allow for the output of the first IF signal, which fed a NASA developed receiver/detector subsystem. The NASA receiver incorporated a distributed, high-speed digital attenuator, producing a range bin to range bin automatic gain control system with 65 dB of dynamic range. Using group speed information supplied by the aircraft's navigation system, the radar signal is frequency demodulated back to base band (zero Doppler relative to stationary ground). The In-phase & Quadrature-phase (I/Q) components of the measured voltage signal are then digitized by a 12-bit A-D converter (producing an additional 36 dB of dynamic range). The raw I/Q signal for each range bin is then recorded (along with the current radar & aircraft state parameters) by a high-speed Kodak tape recorder.

Harrah, S. D.; Bracalente, E. M.; Schaffner, P. R.; Baxa, E. G.

1993-01-01

417

Multi-platform RF emitter localization using extremum seeking control  

NASA Astrophysics Data System (ADS)

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

Al Issa, Huthaifa; Ordez, Ral

2013-05-01

418

Emittance measurements of the CLIO electron beam  

NASA Astrophysics Data System (ADS)

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

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

1997-02-01

419

Directional emittance surface measurement system and process  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

420

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

DOEpatents

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

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

2014-10-07

421

Delineate subsurface structures with ground penetrating radar  

SciTech Connect

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

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

1992-01-01

422

Delineate subsurface structures with ground penetrating radar  

SciTech Connect

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

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

1992-10-01

423

Positron emitter labeled enzyme inhibitors  

SciTech Connect

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

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

1990-04-03

424

Low Emittance Electron Beam Studies  

SciTech Connect

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

Tikhoplav, Rodion; /Rochester U.; ,

2006-04-01

425

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

SciTech Connect

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

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

1994-11-18

426

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

SciTech Connect

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

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

1994-12-19

427

Development and characterization analysis of a radar polarimeter  

NASA Technical Reports Server (NTRS)

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

Bong, S.; Blanchard, A. J.

1983-01-01

428

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

E-print Network

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

Miami, University of

429

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

NASA Astrophysics Data System (ADS)

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

Baur, K.

430

Use and Interpretation of Radar  

NSDL National Science Digital Library

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

John Nielsen-Gammon

1996-01-01

431

Low probability of intercept radar  

Microsoft Academic Search

The objective of LPI radars is defined and performance characteristics are examined. A performance criterion relating the range at which the LPI radar can detect a target to the range at which an intercept receiver aboard the target can detect the LPI radar is defined. The response of various operational and advanced intercept receivers to wideband LPI radar waveforms is

D. C. Schleher

1985-01-01

432

Radar sensing of the ocean  

Microsoft Academic Search

Radar remote sensing of the ocean has been the subject of research for about 20 years. Spaceborne radar altimetry and scatterometry are approaching maturity, and synthetic-aperture radars (SAR) show great promise. The principles of radar scattering from the sea are outlined here, along with some recently discovered questions. For wind-vector scatterometry, the principle is presented, and remaining uncertainties are outlined.

RICHARD K. MOORE

1985-01-01

433

Correlation detection filter for imaging laser radar  

NASA Astrophysics Data System (ADS)

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

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

2007-01-01

434

Rendezvous radar for the orbital maneuvering vehicle  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

435

Goldstone solar system radar  

NASA Technical Reports Server (NTRS)

Planning, direction, experimental design, and coordination of data-acquisition and engineering activities in support of all Goldstone planetary radar astronomy were performed. This work demands familiarity with the various components of a planetary radar telescope (transmitter, receiver, antenna, computer hardware and software) as well as knowledge of how the entire system must function as a cohesive unit to meet the particular scientific objectives at hand in a given observation. Support radar data-processing facilities, currently being used for virtually all Goldstone data reduction includes: a VAX 11/780 computer system, an FPS 5210 array processor, terminals, tape drives, and image-display devices, as well as a large body of data-reduction software to accommodate the variety of data-acquisition formats and strategems. Successful 113-cm radar observation of Callisto and the near-Earth asteroid 1981 Midas and Goldstone/VLA radar observations of Saturn's rings were obtained. Quick-look verification programs from data taken with phase-coded cw (i.e., ranging) waveforms, applicable to Venus, the Moon, and small bodies were completed. Definition of scientific and engineering requirements on instrument performance, radar system configuration, and personnel, for all 1988 Goldstone radar investigations was accomplished.

Jurgens, Raymond F.

1988-01-01

436

IEEE National Radar Conference, 3rd, University of Michigan, Ann Arbor, MI, Apr. 20, 21, 1988, Proceedings  

NASA Astrophysics Data System (ADS)

The present conference discusses topics in radar systems and subsystems, radar techniques, radar signal processing, and radar phenomenology. Attention is given to mm-wave radar system tradeoffs, polarimetric X/L/C-band SAR, a VHF radar for tropical jungle terrain elevation modeling, low probability of intercept techniques and implementations, target tracking in maneuver-centered coordinates, advanced techniques for extension of SAR depth-of-focus under arbitrary aircraft maneuvers, and iterative noncoherent angular superresolution. Also discussed are the effect of codebook size on the vector quantization of SAR data, the application of knowledge-based systems to surveillance, digital filters for SAR, novel radar pulse compression waveforms, the theory and application of SAR oceanography, autoregressive modeling of radar data with application to target identification, and a coherent model of radar weather clutter.

437

The preservation of low emittance flat beams  

SciTech Connect

Many future linear collider designs require beams with very small transverse emittances and large emittance ratios {epsilon}{sub x} {much_gt} {epsilon}{sub y}. In this paper, we will discuss issues associated with the preservation of these small emittances during the acceleration of the beams. The primary sources of transverse emittance dilution in a high energy linear accelerator are the transverse wakefields, the dispersive errors, RF deflections, and betatron coupling. We will discuss the estimation of these effects and the calculation of tolerances that will limit the emittance dilution with a high degree of confidence. Since the six-dimensional emittance is conserved and only the projected emittances are increased, these dilutions can be corrected if the beam has not filamented (phase mixed). We discuss methods of correcting the dilutions and easing the tolerances with beam-based alignment and steering techniques, and non-local trajectory bumps. Finally, we discuss another important source of luminosity degradation, namely, pulse-to-pulse jitter.

Raubenheimer, T.O.

1993-04-01

438

Radar Remote Sensing  

NASA Technical Reports Server (NTRS)

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

Rosen, Paul A.

2012-01-01

439

Radar investigation of asteroids  

NASA Technical Reports Server (NTRS)

The initial radar observations of the mainbelt asteroids 9 Metis, 27 Euterpe, and 60 Echo are examined. For each target, data are taken simultaneously in the same sense of circular polarization as transmitted as well as in the opposite (OC) sense. Estimates of the radar cross sections provide estimates of the circular polarization ratio, and the normalized OC radar cross section. The circular polarization ratio, is comparable to values measured for other large S type asteroids and for a few much smaller, Earth approaching objects, most of the echo is due to single reflection backscattering from smooth surface elements.

Ostro, S. J.

1984-01-01

440

Multinozzle Emitter Arrays for Nanoelectrospray Mass Spectrometry  

PubMed Central

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

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

2011-01-01

441

Customizable Digital Receivers for Radar  

NASA Technical Reports Server (NTRS)

Compact, highly customizable digital receivers are being developed for the system described in 'Radar Interferometer for Topographic Mapping of Glaciers and Ice Sheets' (NPO-43962), NASA Tech Briefs, Vol. 31, No. 7 (August 2007), page 72. The receivers are required to operate in unison, sampling radar returns received by the antenna elements in a digital beam-forming (DBF) mode. The design of these receivers could also be adapted to commercial radar systems. At the time of reporting the information for this article, there were no commercially available digital receivers capable of satisfying all of the operational requirements and compact enough to be mounted directly on the antenna elements. A provided figure depicts the overall system of which the digital receivers are parts. Each digital receiver includes an analog-to-digital converter (ADC), a demultiplexer (DMUX), and a field-programmable gate array (FPGA). The ADC effects 10-bit band-pass sampling of input signals having frequencies up to 3.5 GHz. The input samples are demultiplexed at a user-selectable rate of 1:2 or 1:4, then buffered in part of the FPGA that functions as a first-in/first-out (FIFO) memory. Another part of the FPGA serves as a controller for the ADC, DMUX, and FIFO memory and as an interface between (1) the rest of the receiver and (2) a front-panel data port (FPDP) bus, which is an industry-standard parallel data bus that has a high data-rate capability and multichannel configuration suitable for DBF. Still other parts of the FPGA in each receiver perform signal-processing functions. The digital receivers can be configured to operate in a stand-alone mode, or in a multichannel mode as needed for DBF. The customizability of the receiver makes it applicable to a broad range of system architectures. The capability for operation of receivers in either a stand-alone or a DBF mode enables the use of the receivers in an unprecedentedly wide variety of radar systems.

Moller, Delwyn; Heavey, Brandon; Sadowy, Gregory

2008-01-01

442

Narrowband terahertz emitters using metamaterial films.  

PubMed

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

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

2012-09-10

443

Interpretation of MST radar returns from clear air  

NASA Technical Reports Server (NTRS)

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

Liu, C. H.

1983-01-01

444

EMP (electro-magnetic pulse) hardening of a relocatable radar  

NASA Astrophysics Data System (ADS)

The problem of ensuring radar survivability in a HEMP (high-altitude electromagnetic pulse) environment is examined with particular reference to experimental results obtained for the relocatable TRS 22XX radar. The approach used here is global hardening, whereby the whole system except the antenna is enclosed in a Faraday cage. Every penetration of the radar station is protected, the energy input is correctly filtered, and the signal input/output is implemented with optical fibers. Specific technological solutions for HEMP hardening are discussed.

Deville, G. J.

445

Optically isolated signal coupler with linear response  

DOEpatents

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

Kronberg, James W. (Aiken, SC)

1994-01-01

446

Caribbean Radar Products  

NSDL National Science Digital Library

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

2014-09-14

447

GMTI MIMO radar  

E-print Network

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

Bliss, Daniel W., Jr.

448

Imaging with Radar  

NSDL National Science Digital Library

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

2004-01-29

449

Aircraft radar antennas  

NASA Astrophysics Data System (ADS)

Many changes have taken place in airborne radar antennas since their beginnings over forty years ago. A brief historical review of the advances in technology is presented, from mechanically scanned reflectors to modern multiple function phased arrays. However, emphasis is not on history but on the state-of-the-art technology and trends for future airborne radar systems. The status of rotating surveillance antennas is illustrated by the AN/APY-1 Airborne Warning and Control System (AWACS) slotted waveguide array, which achieved a significant breakthrough in sidelobe suppression. Gimballed flat plate arrays in nose radomes are typified by the AN/APG-66 (F-16) antenna. Multifunction phased arrays are presented by the Electronically Agile Radar (EAR) antenna, which has achieved significant advances in performance versatility and reliability. Trends toward active aperture, adaptive, and digital beamforming arrays are briefly discussed. Antennas for future aircraft radar systems must provide multiple functions in less aperture space, and must perform more reliably.

Schrank, Helmut E.

1987-04-01

450

Multipolarization Radar Images for Geologic Mapping and Vegetation Discrimination  

Microsoft Academic Search

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

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

1986-01-01

451

Radar image processing module development program, phase 3  

NASA Technical Reports Server (NTRS)

The feasibility of using charge coupled devices in an IPM for processing synthetic aperture radar signals onboard the NASA Convair 990 (CV990) aircraft was demonstrated. Radar data onboard the aircraft was recorded and processed using a CCD sampler and digital tape recorder. A description of equipment and testing was provided. The derivation of the digital presum filter was documented. Photographs of the sampler/tape recorder, real time display and circuit boards in the IPM were also included.

1977-01-01

452

Downhole pulse radar  

DOEpatents

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

Chang, Hsi-Tien

1987-09-28

453

Doppler Radar Technology  

NSDL National Science Digital Library

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

454

Downhole pulse radar  

DOEpatents

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

Chang, Hsi-Tien (Albuquerque, NM)

1989-01-01

455

Adaptive MIMO radar waveforms  

Microsoft Academic Search

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

Daniel J. Rabideau; Lexington MA

2008-01-01

456

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

PubMed Central

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

Vicen-Bueno, Ral; Carrasco-lvarez, Rubn; Rosa-Zurera, Manuel; Nieto-Borge, Jos Carlos

2009-01-01

457

Sea clutter reduction and target enhancement by neural networks in a marine radar system.  

PubMed

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

Vicen-Bueno, Ral; Carrasco-lvarez, Rubn; Rosa-Zurera, Manuel; Nieto-Borge, Jos Carlos

2009-01-01

458

Wide band stepped frequency ground penetrating radar  

DOEpatents

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

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

1996-03-12

459

Wide band stepped frequency ground penetrating radar  

DOEpatents

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

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

1996-01-01

460

Emitters of N-photon bundles.  

PubMed

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

Muoz, C Snchez; Del Valle, E; Tudela, A Gonzlez; Mller, K; Lichtmannecker, S; Kaniber, M; Tejedor, C; Finley, J J; Laussy, F P

2014-07-01

461

Electrospray emitters For diffusion vacuum pumps  

E-print Network

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

Diaz Gmez Maqueo, Pablo (Pablo Ly)

2011-01-01

462

Arc-textured high emittance radiator surfaces  

NASA Technical Reports Server (NTRS)

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

Banks, Bruce A. (inventor)

1991-01-01

463

Emitters of N-photon bundles  

PubMed Central

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

Muoz, C. Snchez; del Valle, E.; Tudela, A. Gonzlez; Mller, K.; Lichtmannecker, S.; Kaniber, M.; Tejedor, C.; Finley, J.J.; Laussy, F.P.

2014-01-01

464

Emittance growth in linear induction accelerators  

E-print Network

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

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

2014-01-01

465

Target Detection and Localization Using MIMO Radars and Sonars  

Microsoft Academic Search

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

Ilya Bekkerman; Joseph Tabrikian

2006-01-01

466

Multi-static synthetic aperture radar image formation  

Microsoft Academic Search

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

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

2009-01-01

467

MIMO radar: an idea whose time has come  

Microsoft Academic Search

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

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

2004-01-01

468

Muti-Channel Digital LPI Signal Detector  

Microsoft Academic Search

The theory of LPI radar signal interception is introduced and a method using multi-channel digital deramping is discussed in detail for FMCW signals. Many simulation experiments on the method have been done in several possible situations, and on the basis of them, the influences of mismatch factor and unsynchronized phase on the detection performance of the digital LPI radar detector

Song Jie; Tang Xiao-ming; He You

2006-01-01

469

Alpha-emitters for medical therapy workshop  

SciTech Connect

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

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

1996-12-31

470

Coaxial inverted geometry transistor having buried emitter  

NASA Technical Reports Server (NTRS)

The invention relates to an inverted geometry transistor wherein the emitter is buried within the substrate. The transistor can be fabricated as a part of a monolithic integrated circuit and is particularly suited for use in applications where it is desired to employ low actuating voltages. The transistor may employ the same doping levels in the collector and emitter, so these connections can be reversed.

Hruby, R. J.; Cress, S. B.; Dunn, W. R. (inventors)

1973-01-01

471

Reducing RFQ output emittance by external bunching  

SciTech Connect

RFQ accelerators normally incorporate adiabatic bunchers in the accelerator proper. This produces high accelerator acceptance but less-than-optimum longitudinal emittance as a result of severe filamentation of the longitudinal phase space. The use of discrete bunchers both internal and external to the RFQ, along with new approaches in accelerator-only (no adiabatic buncher) RFQ beam dynamics designs produce significantly lower longitudinal output emittance with high acceptance.

Staples, J. [Lawrence Berkeley Lab., CA (United States)

1994-05-01

472

Prospects for a Solar Radar at Arecibo  

NASA Astrophysics Data System (ADS)

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

Coles, W. A.

2002-05-01

473

Monitoring internal organ motion with continuous wave radar in CT  

SciTech Connect

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

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

2013-09-15

474

Progress in coherent laser radar  

NASA Technical Reports Server (NTRS)

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

Vaughan, J. M.

1986-01-01

475

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

E-print Network

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

Rutledge, Steven

476

Radar E-O image fusion  

NASA Technical Reports Server (NTRS)

The fusion of radar and electro-optic (E-O) sensor images presents unique challenges. The two sensors measure different properties of the real three-dimensional (3-D) world. Forming the sensor outputs into a common format does not mask these differences. In this paper, the conditions under which fusion of the two sensor signals is possible are explored. The program currently planned to investigate this problem is briefly discussed.

Oneil, William F.

1993-01-01

477

Amplitude calibration of spaceborne synthetic aperture radars. [Synthetic Aperture Radar  

NASA Technical Reports Server (NTRS)

Problems encountered during attempts to calibrate SAR imagery, recent successful experiments conducted with SEASAT SAR data, and a proposed program for the calibration and validation of the radar imagery from the forthcoming SIR-B SAR are discussed. The SEASAT SAR data for 10 passes over Death Valley, California, were processed with a modified digital correlator. The procedure included a preliminary screening of the data to check for raw data saturation, compensation of waveforms and estimation of the amplitude of the pilot tone. All data was normalized to this pilot tone signal to reduce the effects of variable gains in the data links and ground receivers. The digital correlation algorithm generated image data. Evaluation of 6 passes results in a maximum pass to pass gain variation of only 1.1 dB and a standard deviation amongst the passes of 0.35 dB. previously announced in STAR as N83-26215

Held, D. N.

1983-01-01

478

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

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

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

479

Radar Range Sidelobe Reduction Using Adaptive Pulse Compression Technique  

NASA Technical Reports Server (NTRS)

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

Li, Lihua; Coon, Michael; McLinden, Matthew

2013-01-01

480

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

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

481

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

NASA Astrophysics Data System (ADS)

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

Chen, Jenn-Shyong

2004-10-01

482

Covert Netted Wireless Noise Radar Sensor: OFDMA-Based Communication Architecture  

Microsoft Academic Search

We address the need for covert situational awareness by the effective use of random waveforms in ad-hoc networks, wireless communication, and radar sensors. UWB random noise radar is well-known for its LPD and LPI properties. Notch filtering is used to fragment this radar's band-limited random noise transmit signal and the intermediate bandwidth so obtained is used for establishing a covert

Shrawan C. Surender; R. M. Narayanan

2006-01-01

483

Photonic remoting of AN\\/SPQ-9B ADM ultra high dynamic range radar  

Microsoft Academic Search

We report initial demonstrations of photonic technology meeting the stringent phase noise and signal-to-noise ratio (SNR) requirements for remoting radars. In particular, fiber optic links were used to remote the antenna and transmitter of the Navy AN\\/SPQ-9B ADM radar. The remoting links tested successfully in a transmit configuration without significantly degrading the 87 dB SNR of the radar. These results

J. E. Romsin; L. T. Nichols; K. J. Williams; R. D. Esman; G. C. Tavik; M. Livingston; M. G. Parent

1998-01-01

484

Weather Radar and Instrumentation: Laboratory Modules  

NSDL National Science Digital Library

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

485

Space Radar Image of Raco Biomass Map  

NASA Technical Reports Server (NTRS)

This biomass map of the Raco, Michigan, area was produced from data acquired by the Spaceborne Imaging Radar C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) onboard space shuttle Endeavour. Biomass is the amount of plant material on an area of Earth's surface. Radar can directly sense the quantity and organizational structure of the woody biomass in the forest. Science team members at the University of Michigan used the radar data to estimate the standing biomass for this Raco site in the Upper Peninsula of Michigan. Detailed surveys of 70 forest stands will be used to assess the accuracy of these techniques. The seasonal growth of terrestrial plants, and forests in particular, leads to the temporary storage of large amounts of carbon, which could directly affect changes in global climate. In order to accurately predict future global change, scientists need detailed information about curre