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1

Radar emitter signal recognition based on support vector machines  

Microsoft Academic Search

Radar emitter signal recognition plays an important role in electronic intelligence systems and electronic support measure systems. To heighten accurate recognition rate of radar emitter signals, this paper proposes a hierarchical classifier structure to recognize radar emitter signals. The proposed structure combines resemblance coefficient classifier, support vector machines with binary tree architecture and linear classifier based on Mahalanobis distance. Experimental

Gexiang Zhang; Weidong Jin; Laizhao Hu

2004-01-01

2

Radar Emitter Signal Recognition Based on Resemblance Coefficient Features  

Microsoft Academic Search

\\u000a Resemblance coefficient (RC) feature extraction approach for radar emitter signals was proposed. Definition and properties\\u000a of RC were given. Feature extraction algorithm based on RC was described in detail and the performances of RC features were\\u000a also analyzed. Neural network classifiers were designed. Theoretical analysis results and simulation experiments of 9 typical\\u000a radar emitter signal feature extraction and recognition show

Gexiang Zhang; Haina Rong; Weidong Jin; Laizhao Hu

2004-01-01

3

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

Microsoft Academic Search

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

Gexiang Zhang

2006-01-01

4

Radar Emitter Signal Recognition Based on Feature Selection and Support Vector Machines  

Microsoft Academic Search

\\u000a One of the intelligent aspects of human beings in pattern recognition is that man identifies an object in real world using\\u000a Marked Characteristic Principle (MCP). This paper proposes a humanoid recognition method for radar emitter signals. The main\\u000a points of the method include feature ordering and an improved one-versus-rest multiclass classification support vector machines.\\u000a According to MCP, an approach for

Gexiang Zhang; Zhexin Cao; Yajun Gu; Weidong Jin; Laizhao Hu

2005-01-01

5

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

Microsoft Academic Search

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

Gexiang Zhang; Haina Rong; Weidong Jin

6

The method for radar signal recognition  

NASA Astrophysics Data System (ADS)

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

Kawalec, A.; Owczarek, R.

2006-11-01

7

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

8

A new algorithm for radar emitter recognition  

Microsoft Academic Search

A radar electronic support measures (ESM) system performs the functions of threat detection and area surveillance. The received radar pulses are sorted and segregated by the deinterleaver into a number of radar cells depending on the measured parameters of the received pulses. These radar cells will be submitted to the threat library and compared with the stored parameters of known

H. E. Hassan

2003-01-01

9

Radar signal processing  

NASA Astrophysics Data System (ADS)

The role of clutter in radar signal processing is considered with particular reference to an air-traffic environment. The characteristics of clutter are described, and the use of conventional moving-target indication filters to reduce the effects of clutter is considered. Adaptive clutter suppression schemes are addressed, and the adaptive detection of a moving target in the presence of clutter of unknown statistics is discussed. The use of a parametric spectrum estimation procedure as the basis of clutter classification is described.

Haykin, S.

1985-04-01

10

Knowledge-based signal processing for radar ESM systems  

NASA Astrophysics Data System (ADS)

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

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

1990-10-01

11

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

12

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

13

A WhatandWhere Fusion Neural Network for Recognition and Tracking of Multiple Radar Emitters  

E-print Network

A What­and­Where Fusion Neural Network for Recognition and Tracking of Multiple Radar Emitters Eric information is combined with position­specific information from active emitters in a scene. Type collected in the field. Meanwhile, a clustering algorithm is used to separate pulses from different emitters

Grossberg, Stephen

14

A What-and-Where Fusion Neural Network for Recognition and Tracking of Multiple Radar Emitters  

E-print Network

A What-and-Where Fusion Neural Network for Recognition and Tracking of Multiple Radar Emitters Eric is combined with position-specific information from active emitters in a scene. Type-specific parameters in the field. Meanwhile, a clustering algorithm is used to separate pulses from different emitters according

Grossberg, Stephen

15

Knowledge-based signal processing for radar ESM systems  

Microsoft Academic Search

Radar electronic support measures (ESM) systems perform the functions of threat detection and area surveillance to determine the identity and bearing of surrounding radar emitters. Automatic ESM systems incorporate a passive receiver to measure the parameters of detected radar pulses and an automatic processor to rapidly sort pulses and identify the emitters. Current processors use algorithmic processing methods which are

J. Roe; S. Cussons; A. Feltham

1990-01-01

16

3D AOA\\/TDOA emitter location by integrated passive radar\\/GPS\\/INS systems  

Microsoft Academic Search

3D passive geolocation of radar emitters is an important problem in electronic support for military surveillance. The angle of arrivals (AOA) and time difference of arrivals (TDOA) are two popular schemes for passive emitter location. In this paper, a location scheme is proposed based on fusion of AOA and TDOA measurements from two electronic support measures (ESM) sensors installed on

Wenhua Li; Peiguo Liu

2005-01-01

17

Radar Signals Sorting with Kohonen Neural Net  

Microsoft Academic Search

Kohonen neural network is capable of self-organizing and recognizing clustering center, which is used in many artificial Intelligence (AI) fields. A radar electronic support measures (ESM) system must sort the received radar pulse signal to cells with the same features according to the single pulse parameters, such as radio frequency (RF), angle of arrival (AOA), pulse width (PW), etc. Considering

Chuang Zhao; Yongjun Zhao; Jianqi Lu

2006-01-01

18

A What-and-Where fusion neural network for recognition and tracking of multiple radar emitters  

Microsoft Academic Search

A neural network recognition and tracking system is proposed for classification of radarpulses in autonomous Electronic Support Measure systems. Radar type information is combinedwith position-specific information from active emitters in a scene. Type-specific parameters ofthe input pulse stream are fed to a neural network classifier trained on samples of data collectedin the field. Meanwhile, a clustering algorithm is used to

Eric Granger; Mark A. Rubin; Stephen Grossberg; Pierre Lavoie

2001-01-01

19

Optical signal processing in Radar systems  

Microsoft Academic Search

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

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

2006-01-01

20

Karhunen - Loeve Transformation in Radar Signal Features Processing  

Microsoft Academic Search

One of the most difficult tasks in the radar signal processing is an optimal features extraction and classification. The multifunction radar systems can not be classified and precisely recognized by most of new and modern Electronic Support Measure and Electronic Intelligence devices in the real time. It is directly combined with a possibility of measurement radar features. The number of

A. Kawalec; R. Owczarek; J. Dudczyk

2006-01-01

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

The signal subspace approach for multiple wide-band emitter location  

Microsoft Academic Search

The rational vector space generalization of the signal subspace approach is presented and applied to the estimation of multiple wide-band emitter locations from the signals received at multiple sensors. The signal subspace and array manifold concepts first introduced by Schmidt are generalized to rational vector space. These concepts are used to develop the rational signal subspace theory and prove the

Guaning Su; MARTIN MORF

1983-01-01

23

Signal Interpretation of Multifunction Radars: Modeling and Statistical Signal Processing With Stochastic Context Free Grammar  

Microsoft Academic Search

Multifunction radars (MFRs) are sophisticated sensors with complex dynamical modes that are widely used in surveillance and tracking. Because of their agility, a new solution to the interpretation of radar signal is critical to aircraft survivability and successful mission completion. The MFRs' three main characteristics that make their signal interpretation challenging are: i) MFRs' behavior is mission dependent, that is,

Alex Wang; Vikram Krishnamurthy

2008-01-01

24

Enhancement of radar signals by double bounce circular polarization  

Microsoft Academic Search

On the basis of available radar data, most of it concerning linear polarization, it had been postulated that although in the worst conditions of rain a circularly polarized signal may return distorted into an elipse, it would still be distinguishable from other polarizations and could be used to discriminate targets from ground clutter. Since a circularly polarized signal which was

S. Isaacson

1961-01-01

25

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

26

Joint utilization of incoherently and coherently integrated radar signal in helicopter categorization  

Microsoft Academic Search

Radar signal based helicopter categorization is a challenging task for all types of radars. Airborne pulse Doppler radar with an appropriate digital signal processing unit has a good potential to perform categorization or even classification, providing that radar parameters are carefully selected. This paper presents a helicopter categorization method, which is based on estimation of the main rotor blade tip

Jani M. Tikkinen; Elina E. Helander; A. Visa

2005-01-01

27

Bistatic noise radar using locally generated reference signal  

Microsoft Academic Search

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

Mateusz Malanowski; Pawel Roszkowski

2011-01-01

28

Wavelet Transformation and Signal Discrimination for HRR Radar Target Recognition  

Microsoft Academic Search

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

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

2003-01-01

29

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

30

Atmospheric Radar Signal Processing using Bivariate Empirical Mode Decomposition  

NASA Astrophysics Data System (ADS)

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

Sreenivasulu Reddy, Thatiparthi

2012-07-01

31

Numerical Modeling of Doppler Radar Signals of Strombolian Eruptions  

NASA Astrophysics Data System (ADS)

VOLDORAD is a ground-based UHF Doppler radar developed specifically for the remote sounding of volcanic eruptions. Its 23.5 cm wavelength allows us to monitor and quantify eruption intensity in real time from several km, with negligible attenuation by meteorological effects or volcanic ash. In particular, the signal can penetrate inside volcanic jets or plumes to measure the reflectivity and velocities of ejecta in several sampling volumes. The precise knowledge of these parameters is crucial to monitoring the evolution of an eruption and to provide more stringent constraints on assumptions included in models of volcanic processes. To improve our interpretation of radar signals, we have developed a numerical model simulating radar echoes from Strombolian jets. Ballistic projectiles of various sizes are accelerated upwards, over a range of angles, by gas with a given imposed initial velocity , and the equations of motion are solved with a fourth-order Runge-Kutta algorithm. The power backscattered to the radar is simulated by Rayleigh scattering from spheres. Taking into account the sounding geometry used for measurements on Etna in July 2001, our model is able to reproduce many characteristic trends of the time series and Doppler spectra measured during repeated Strombolian outbursts. Models show that measured radar velocities depend mostly on jet geometry, particle size, and initial gas velocity. For wide emission angles, measured radial velocities can be considered as the real ejecta velocities, whereas in the case of narrow vertical or asymmetrical jets, real velocity might be underestimated. However, video analyses confirm that for the majority of explosions, although most particles concentrate in the inner part of the jets, many blocks are also emitted at wide angles. For instance, maximum radial velocities recorded during the July 4 episode of Etna reached 70 m/s. The model radar signal obtained is strongly dependent on the degree of coupling between projectile and the gas phase, and this in turn depends on the projectile size. Comparing measured with computed reflectivities provides constraints on particle size distribution. In particular, particle size has a larger effect on reflectivity than particle number. Such constraints allow us to estimate the initial gas velocity, crucial to improve gas flux estimation.

Gouhier, M.; Donnadieu, F.

2006-12-01

32

Polarization vector signal processing for radar clutter suppression  

NASA Astrophysics Data System (ADS)

The statistical model of a radar scatterer illuminated and observed on one channel is extended to suit the two-channel polarization case, accounting for statistical range and Doppler-spread characteristics. The mathematical formulation for the polarization-sensitive scatterer was written in the framework of a random process scattering matrix whose covariance properties took on a sixteen-element tensor of the fourth rank. Each element is expressed in terms of its correlation with respect to range and Doppler; this tensor contained all the backscatter data needed for determining the range/time/polarization-dependent behavior of the received signal for any arbitrary transit polarized waveform.

Vannicola, V. C.; Lis, S.

33

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

34

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

E-print Network

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

Stoffelen, Ad

35

I\\/Q demodulation of radar signals with calibration and filtering  

Microsoft Academic Search

A simple in-phase quadrature (I\\/Q) demodulator architecture which can measure the amplitude, phase, and instantaneous frequency of radar signals is examined. This architecture has the potential for radar electronic support measure applications where wide instantaneous bandwidth and simple algorithms for extracting the modulation characteristics of radar signals are required. This I\\/Q architecture can meet the requirement by splitting an incoming

Jim P. Y. Lee

1991-01-01

36

On Mary Sequential Hypothesis Testing for the Classification of Radar Signals  

Microsoft Academic Search

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

F. D. Garber; I. Jouny

1987-01-01

37

Monitoring of weather radar receivers using solar signals detected in operational scan data  

E-print Network

-way gaseous attenu- ation, and f the receiver bandwidth. The mean solar power ¯Pf , power standard deviationMonitoring of weather radar receivers using solar signals detected in operational scan data Iwan during radar mainte- nance. Solar signals can, however, be detected automatically in polar reflectivity

Stoffelen, Ad

38

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

39

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

Microsoft Academic Search

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

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

2005-01-01

40

Frequency estimation of radar signals using an acousto-optic spectrum analyzer as an RESM (Radar Electronic Support Measures) receiver  

Microsoft Academic Search

In this report we present a statistical model for the signals of an acousto-optic spectrum analyzer (AOSA). Using the model, we calculate the Cramer-Rao bound for the estimation of the carrier frequency of radar signals and the performance of the peak detector estimator. We also present an algorithm for sidelobe rejection.

Guy Farley

1988-01-01

41

Virtual hyperbolic metamaterials for manipulating radar signals in air.  

PubMed

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

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

2013-01-01

42

Some signal-processing issues in radar-target identification  

NASA Astrophysics Data System (ADS)

Three issues in radar target identification are discussed: (1) the performance characteristics of Prony-like signal processing for estimating EM features, from the viewpoint of an input-output information transformation; (2) pole (and singularity) sets of EM features obtained from computed EM data for several situations; (3) some initial results of using frequency domain poles for target identification. It is demonstrated for data similar to that which occurs in sampling EM fields, that Prony's Method seems to preserve information, that give poles values whose accuracy on the average equals the accuracy of the input data. However, the imaginary (oscillation) components are almost always found with greater accuracy than the real (decay) components, whose accuracy seems more closely correlated to that of the predictor coefficients. The richness of the pole-based representation for EM problems is shown by giving sample results from transient data, linear-array patterns, and plane wave scattering from a half space. Finally, various target identification schemes using frequency domain poles is compared as a function of signal to noise level, with the tentative finding that improved performance seems to occur at the expense of increased computational effort.

Miller, E. K.

1982-09-01

43

Impact of Wavelet based signal processing methods in radar classification systems using Hidden Markov Models  

Microsoft Academic Search

A classification technology is presented that uses a Wavelet based feature extractor and a Hidden Markov Model (HMM) to classify simulated and real radar signals from six classes of targets: person, tracked vehicles, wheeled vehicles, helicopters, propeller aircrafts and clutter (no match). Similar to techniques that have been well proven in speech and image recognition, the time-varying nature of radar

G. Kouemou; F. Opitz

2008-01-01

44

The quadriphase code - A radar pulse compression signal with unique characteristics  

NASA Astrophysics Data System (ADS)

A unique class of radar signals (the quadriphase codes) which may be of use in pulse compression applications is described. The codes investigated are particularly attractive for radars using digital processing for Doppler filtering, pulse compression, and CFAR operation. The quadriphase code employs subpulses of half-cosine shape, resulting in a spectrum fall-off of 12 dB/octave.

Taylor, J. W., Jr.; Blinchikoff, H. J.

45

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

NASA Astrophysics Data System (ADS)

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

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

1991-10-01

46

Emittance simulations Emittance simulations  

E-print Network

1 Emittance simulations Emittance simulations Pavel Snopok IIT/Fermilab April 8, 2011 #12;2 Emittance simulations Introduction Emittance calculation = cov(x, px , y, py , t, -E); 6D = c m3 det, where J is a block diagonal matrix made up of three blocks J2 = 0 1 -1 0 . |1|, |2|, |3| ­ eigen-emittances

McDonald, Kirk

47

Optimal Signal Processing of Frequency-Stepped CW Radar Data  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

48

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

49

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

50

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

51

Radar signal pre-processing to suppress surface bounce and multipath  

DOEpatents

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

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

2013-12-31

52

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

53

Advanced burden level measurement radars using FFT signal processing techniques. [Fast Fourier Transform  

Microsoft Academic Search

Advanced design level-measuring radars have been developed and installed at Bethlehem Steel's Burns Harbor Plant to measure burden height in operating blast furnaces. Modern signal processing techniques are used in conjunction with a self-calibrating wideband swept-frequency dual-antenna radar to enhance measurement accuracy and better differentiate true surface returns from extraneous reflections. Provisions have been included to monitor and record critical

D. D. Mawhinney; A. Presser; T. G. Koselke

1993-01-01

54

IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 44, NO. 9, SEPTEMBER 2006 2393 Landmines Ground-Penetrating Radar Signal  

E-print Network

Ground-Penetrating Radar Signal Enhancement by Digital Filtering Delphine Potin, Emmanuel Duflos, Member problems have been raised by these sensors. Ground-penetrating radars (GPRs) are key sensors for landmine. Thanks to the sensors, the technology is available. The ground-penetrating radar (GPR) has an im- portant

Paris-Sud XI, Université de

55

SARAS: a synthetic aperture radar (SAR) raw signal simulator  

Microsoft Academic Search

An SAR simulator of an extended three-dimensional scene is presented. It is based on a facet model for the scene, asymptotic evaluation of SAR unit response, and a two-dimensional fast Fourier transform code for the data processing. Prescribed statistics of the model account for a realistic speckle of the image. The simulator is implemented in Synthetic Aperture Radar Advance Simulators

Giorgio Franceschetti; Maurizio Migliaccio; Daniele Riccio; Gilda Schirinzi

1992-01-01

56

Polarization vector signal processing for radar clutter suppression  

Microsoft Academic Search

The statistical model of a radar scatterer illuminated and observed on one channel is extended to suit the two-channel polarization case, accounting for statistical range and Doppler-spread characteristics. The mathematical formulation for the polarization-sensitive scatterer was written in the framework of a random process scattering matrix whose covariance properties took on a sixteen-element tensor of the fourth rank. Each element

V. C. Vannicola; S. Lis

1985-01-01

57

Recent Advances in Instantaneous Parameters Analysis of Ground Penetrating Radar (GPR) Signals for AP Mine Detection  

Microsoft Academic Search

Ground Penetrating Radar(GPR) is a promising technology to detect and identify buried Anti-Personnel (AP) non-metallic mines. This paper focusses on GPR signal processing and identification methods. The Wavelet Transform (WT) method is used to analyse impulsive GPR signals scattered by an AP plastic mines. The instantaneous parameters of the signals are calculated. In order to increase the amplitude or energy

Fang Guangyou; Michele Pipan

2000-01-01

58

Pseudowhitening of weather Radar signals to improve spectral moment and polarimetric variable estimates at low signal-to-noise ratios  

Microsoft Academic Search

Pseudowhitening of oversampled signals in range is proposed as a method to improve the performance of spectral moment and polarimetric variable estimators on weather surveillance radars. In an attempt to overcome the noise sensitivity of the whitening transformation, a solution based on the minimum mean-square-error criterion is considered first; however, this transformation is less practical than whitening because it requires

Sebastin M. Torres; Christopher D. Curtis; J. R. Cruz

2004-01-01

59

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

NASA Astrophysics Data System (ADS)

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

Bishop, Chris

1995-03-01

60

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

61

Advanced burden level measurement radars using FFT signal processing techniques. [Fast Fourier Transform  

SciTech Connect

Advanced design level-measuring radars have been developed and installed at Bethlehem Steel's Burns Harbor Plant to measure burden height in operating blast furnaces. Modern signal processing techniques are used in conjunction with a self-calibrating wideband swept-frequency dual-antenna radar to enhance measurement accuracy and better differentiate true surface returns from extraneous reflections. Provisions have been included to monitor and record critical parameters of the radar and various installation accessories to improve maintainability and instrumentation accuracy. A ruggedized personal computer is used to perform the signal processing calculations, determine the distance in terms related to the furnace dimensions, sequence the remote monitoring elements, provide graphic displays of the real-time and historic burden height and monitor data, and operate the complete system from a basic keyboard.

Mawhinney, D.D. (MMTC, Inc., Princeton, NJ (United States)); Presser, A. (MMTC, Inc., Princeton, NJ (United States)); Koselke, T.G. (Bethlehem Steel Corp., Chesterton, IN (United States))

1993-01-01

62

A new parameter extraction technique for small-signal equivalent circuit of polysilicon emitter bipolar transistors  

Microsoft Academic Search

We propose a new parameter extraction method for advanced polysilicon emitter bipolar transistors. This method is based on the predetermination of equivalent circuit parameters using the analytical expressions of de-embedded Z-parameters of these devices. These parameter values are used as initial values for the parameter extraction process using optimization. The entire device equivalent circuit, containing RF probe pad and interconnection

Seonghearn Lee; Byung R. Ryum; Sang Won Kang

1994-01-01

63

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 radio waves reflect off structures in a turbulent meteor trail. These trails persist from a few nonspecular trails and find that the meteoroid energy causes much of the variability in the nonspecular trail

Oppenheim, Meers

64

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

2006-10-26

65

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

Microsoft Academic Search

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

Yong Rin; Benchao Sie; Lui Yongtan

1993-01-01

66

Iterated wavelet transformation and signal discrimination for HRR radar target recognition  

Microsoft Academic Search

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

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

2003-01-01

67

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

68

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

69

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

70

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

71

Doppler Frequency Geolocation of Uncooperative Radars  

Microsoft Academic Search

Passive geolocation of uncooperative radar emitters remains an important problem in radar electronic warfare. Several location estimation techniques have been investigated in the past. In this paper, we present a passive geolocation technique for radar emitters using Doppler frequency measurements. For uncooperative sources, neither the emitter location, nor its transmitted frequency is known a priori. The relationship between these unknowns

B. H. Lee; Y. T. Chan; F. Chan; Huai-Jing Du; Fred A. Dilkes

2007-01-01

72

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

E-print Network

suggested that the geostatistical structure of ground-penetrating radar data may be representative In a hydrogeophysical context, ground-penetrating radar (GPR) surveys find application in contaminant charac- terizationEffects of Signal Processing and Antenna Frequency on the Geostatistical Structure of Ground-Penetrating

Barrash, Warren

73

Microwave emitter position location: present and future  

Microsoft Academic Search

Position location (determination) of enemy microwave emitters (radars and jammers) is one of the most important tasks of electronic warfare (EW) systems, particularly for electronic intelligence (ELINT) and electronic support measures (ESM) systems. Correctly performed location of those emitters yields data allowing one to deduce an allocation of enemy radar-controlled weapon systems, to detect associated threats and makes possible the

Leslaw R. Paradowski; S. Kaliski

1998-01-01

74

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

75

Matched filtering algorithm based on phase-shifting pursuit for ground-penetrating radar signal enhancement  

NASA Astrophysics Data System (ADS)

The received signals from ground-penetrating radar (GPR) contain round-trip echoes, clutters, and complex noise signals. These jamming signals seriously affect the interpretation precision of shallow geological subsurface information. In order to dissolve some useless signals in GPR signals, it is necessary to take appropriate measures to repress interference. Based on the electromagnetic field theory, the propagation characteristics of the transmitted GPR signal are analyzed. On this basis, a matched filtering algorithm based on phase-shifting pursuit is proposed to enhance the received GPR signals. At first, the intrinsic component libraries (ICL) can be generated by changing the phase of the transmitted GPR signal. Then, the correlation analysis between the local information of the received GPR signals extracted by sliding window method and each sample in ICL is studied to extract target echo signals. Experiments based on the GPR imaging demonstrate that the proposed algorithm could enhance the target echo signals to a certain extent. The integrated side lobe ratio of the imaging result of the enhanced GPR signals is 6.33 dB lower than the original ones. The resolution of target imaging can be improved.

Zhang, Hairu; Ouyang, Shan; Wang, Guofu; Wu, Suolu; Zhang, Faquan

2014-01-01

76

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

77

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

NASA Technical Reports Server (NTRS)

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

Clark, Douglas J.; Lux, James P.; Shirbacheh, Mike

2002-01-01

78

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

NASA Astrophysics Data System (ADS)

Laser radar has been widely used these years and the hardware-in-the-loop (HWIL) testing of laser radar become important because of its low cost and high fidelity compare with On-the-Fly testing and whole digital simulation separately. Scene generation and projection two key technologies of hardware-in-the-loop testing of laser radar and is a complicated problem because the 3D images result from time delay. The scene generation process begins with the definition of the target geometry and reflectivity and range. The real-time 3D scene generation computer is a PC based hardware and the 3D target models were modeled using 3dsMAX. The scene generation software was written in C and OpenGL and is executed to extract the Z-buffer from the bit planes to main memory as range image. These pixels contain each target position x, y, z and its respective intensity and range value. Expensive optical injection technologies of scene projection such as LDP array, VCSEL array, DMD and associated scene generation is ongoing. But the optical scene projection is complicated and always unaffordable. In this paper a cheaper test facility was described that uses direct electronic injection to provide rang images for laser radar testing. The electronic delay and pulse shaping circuits inject the scenes directly into the seeker's signal processing unit.

Wang, Qian; Lu, Wei; Wang, Chunhui; Wang, Qi

2005-01-01

79

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

NASA Astrophysics Data System (ADS)

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

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

2008-06-01

80

Topics in radar signal processing. I - Overview and coherent processing techniques  

NASA Astrophysics Data System (ADS)

A survey is presented of some of the principal processing features of a modern pulsed search radar. Emphasis is placed on system considerations and performance characteristics, the A/D conversion process being the only hardware aspect addressed. It is noted that this operation is the key to transforming analog IF radar signals into an accurate equivalent complex digital representation. Attention is given to matched filters and pulse compression and to clutter rejection, with descriptions given of moving target indicators and pulse Doppler processors. It is pointed out that many techniques which in the past have been considered too cumbersome or impractical to implement can now be included at reasonable levels of complexity and cost.

Hansen, V. G.

1984-03-01

81

A new approach to enhancement of ground penetrating radar target signals by pulse compression  

NASA Astrophysics Data System (ADS)

Ground penetrating radar (GPR) is an effective tool for detecting shallow subsurface targets. In many GPR applications, these targets are veiled by the strong waves reflected from the ground surface, so that we need to apply a signal processing technique to separate the target signal from such strong signals. A pulse-compression technique is used in this research to compress the signal width so that it can be separated out from the strong contaminated clutter signals. This work introduces a filter algorithm to carry out pulse compression for GPR data, using a Wiener filtering technique. The filter is applied to synthetic and field GPR data acquired over a buried pipe. The discrimination method uses both the reflected signal from the target and the strong ground surface reflection as a reference signal for pulse compression. For a pulse-compression filter, reference signal selection is an important issue, because as the signal width is compressed the noise level will blow up, especially if the signal-to-noise ratio of the reference signal is low. Analysis of the results obtained from simulated and field GPR data indicates a significant improvement in the GPR image, good discrimination between the target reflection and the ground surface reflection, and better performance with reliable separation between them. However, at the same time the noise level slightly increases in field data, due to the wide bandwidth of the reference signal, which includes the higher-frequency components of noise. Using the ground-surface reflection as a reference signal we found that the pulse width could be compressed and the subsurface target reflection could be enhanced.

Gaballah, Mahmoud; Sato, Motoyuki

2009-02-01

82

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

Microsoft Academic Search

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

Meng Xiangwei; Guan Jian; He You

2003-01-01

83

Radar target classification and interpretation by means of structural descriptions of backscatter signals  

NASA Astrophysics Data System (ADS)

An approach to radar target classification that exploits the relationship between the physical structure of the observed target and the down-range (polarimetric) cross section of the measured backscatter response is presented. The term 'structure' refers to parameters such as the relative range between down-range scattering centers, their relative size, and, when polarization-diverse measurements are available, their relative polarimetric characteristics, including ellipticity and tilt angle. The radar backscatter signal measurements are represented as a set of down-range scattering centers parameterized by a Prony modeling technique. The relative range, size, and polarimetric shape of the resulting parametric centers are used to describe the structure of the target. These structural descriptions of the measured backscatter signal are used to classify the target. This investigation is prompted by practical scenarios in which the characteristics of the measured signal may be significantly altered by an addition to or deletion from the standard target operating configuration. In these cases, the present approach can localize the effect of such a change and minimize its effects on the classification or interpretation of the target.

Silverstein, Paul B.; Sands, O. Scott; Garber, Fred D.

1991-05-01

84

Date 12/01/02 2:56 PM Iterative Wavelet Transformation and Signal Discrimination for HRR Radar  

E-print Network

Date 12/01/02 2:56 PM page 1 Iterative Wavelet Transformation and Signal Discrimination for HRR of discriminant features in the target recognition problem using High Range Resolution (HRR) radar signals the performance to approach an asymptote. I. INTRODUCTION Most of the work in HRR target recognition has been done

Starzyk, Janusz A.

85

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

86

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

87

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

88

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

89

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

90

Identification of electromagnetic parameters of a wall and determination of radar signal level behind a wall  

NASA Astrophysics Data System (ADS)

One of the challenges of using synthetic aperture radar (SAR) to detect a man behind a wall is determining the amount of signal attenuation introduced by the signal's propagation through the wall. This attenuation is difficult to determine because the thickness and the electromagnetic properties of the wall are normally not known a priori. We describe a procedure for estimating the relative permittivity, conductivity, and thickness of the wall that minimize the error between physics-based predicted values of wall return and the corresponding values of the SAR image. The accuracy of the prediction is a function of the resolution of the SAR image relative to the thickness of the wall-the SAR image must have sufficient resolution such that the locations of the front and rear surfaces of a uniform wall can be estimated from the SAR image. The signal level behind the wall, or equivalently the signal attenuation by the wall is then determined from the estimates of the thickness and electromagnetic parameters. We demonstrate the effectiveness of this identification procedure using data generated by XPATCH simulations of three different wall materials.

Khatri, Hiralal; Le, Calvin

2006-05-01

91

Signal structure of the over-the-horizon sea surface radar  

NASA Astrophysics Data System (ADS)

Obtaining information about the state of the sea surface using HF radars has been the subject of intense investigations during the past several decades. Most theoretical investigations made to date have adopted, as the incident wave, a plane wave with a certain wave vector. In real conditions, however, with the finite beam width, the ionosphere-reflected beam of waves of a finite width is usually incident on the scattering sea surface, which must be taken into account when investigating the form of the spectrum and processing it by extracting information about the sea surface. This paper investigates the scattering of fluctuating ionospheric radio waves from the sea surface within limits of the geometrical optics by taking into consideration the finiteness of the beam of the receive and transmit antennas. A numerical simulation is used to investigate the influence of the finiteness of the beam width, the time of coherent integration, and ionospheric irregularities on the structure of the spectrum of the received signal of the overt-the-horizon sea surface radar.

Ignatenko, M. V.; Tinin, Mikhail V.

2002-02-01

92

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

93

HF Radar Sounding of TIDs with the Use of the DPS System and Signals from Broadcasting Stations  

Microsoft Academic Search

Atmospheric gravity waves (AGW) propagating in the ionosphere produce quasiperiodic varia- tions of the ionospheric electron density, known as traveling ionospheric disturbances (TID). In its turn, these wavelike processes modulate parameters of the radio signals in the medium; this effect is widely used for the remote sensing of TIDs. For example, paper (1) presents a bistatic radar technique for recovering

V. S. Beley; V. G. Galushko; D. Paznukhov; B. W. Reinisch; Y. M. Yampolski

94

Innovative tools for radar signal processing Based on Cartans geometry of SPD matrices & Information Geometry  

Microsoft Academic Search

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

F. Barbaresco

2008-01-01

95

Signal sorting in ESM systems  

NASA Astrophysics Data System (ADS)

The paper discusses the problem of developing automatic sorting of radar environments, in order to assist, and eventually replace, the ESM (electronic support measures) equipment operator. The paper separates the signal sorting problem into two subproblems of describing the radar environment in a pulse-train sorter and monitoring changes in the perceived environment in a new-signal detector. Emphasis is placed on the need to use all available pulse parameter measurement data in order to achieve the highest possible confidence in the descriptions of the emitters which the signal sorter provides.

Whittall, N. J.

1985-07-01

96

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

97

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

98

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

Microsoft Academic Search

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

Qian Wang; Wei Lu; Chunhui Wang; Qi Wang

2005-01-01

99

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

100

Laser radar  

Microsoft Academic Search

The general theory of laser tracking and ranging and the principles governing the design of laser radar systems are examined. Major problems related to optimum reception of laser radar signals and parameter measurement are analyzed from the standpoint of the theory of statistical solutions. Attention is given to methods for processing trajectory measurements and various methods for obtaining noncoordinate information,

I. N. Matveev; V. V. Protopopov; I. N. Troitskii; N. D. Ustinov

1984-01-01

101

Development of two-dimensional parametric radar signal modeling and estimation techniques with application to target identification  

NASA Astrophysics Data System (ADS)

One and two dimensional signal processing models and algorithms which are utilized in the Radar Target Identification Problem are developed. A basic assumption of this work is that the high-frequency scattering from a radar target, such as an aircraft, land-based vehicle, or ship, is comprised of the sum of the scattering from a finite number of canonical scattering centers, each with a specific location and identity. By high-frequency it is meant that the overall size of the target is at least one wavelength. The scattering center assumption is more valid as the individual scattering centers become more electrically isolated. If two individual scattering centers are electrically close, then their combined response is, in general, not the sum of their individual responses. First, this dissertation investigates the electromagnetic scattering characteristics of canonical scattering centers. Canonical scattering centers are scattering centers on a target which account for the vast majority of the scattering from that target in the high-frequency case. Some of the targets of interest in this work are aircraft, tanks, trucks, automobiles, and ships. Predominant scattering centers on these targets include corners, edges, plates, dihedrals, trihedrals, and cylinders. The scattering centers are described by their scattering characteristics as functions of angle, frequency, and polarization. Second, this dissertation develops a two-dimensional (2-D) signal processing technique for locating and characterizing scattering centers from radar data. The radar gathers scattering data of a target at both multiple frequencies and multiple angles. This type of data is gathered (in raw form) by both Synthetic Aperture Radars and Inverse Synthetic Aperture Radars. The 2-D signal processing technique developed here is based on a 2-D extension of a total least squares (TLS) solution to a Prony Model and is called the 2-D TLS-Prony Technique. This technique can use single or multiple-polarization data. With full-polarization data, polarimetric characteristics of the scattering centers are found using the transient polarization response concept. This concept uses an ellipse to characterize the polarimetric characteristics of each scattering center. The abilities of the 2-D TLS-Prony Technique are demonstrated utilizing simulated 2-D radar data.

Sacchini, Joseph J.

1992-09-01

102

Joint deinterleaving\\/recognition of radar pulses  

Microsoft Academic Search

A radar electronic support measures (ESM) system performs the functions of threat detection and area surveillance to determine the bearing and the identity of the surrounding radar emitters. The received pulses arc sorted and segregated into a number of deinterleaved radar cells depending on their measured parameters. The parameters of the deinterleaved radar cells will be submitted to the threat

H. E. Hassan

2003-01-01

103

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

104

Thvenin Emitter Circuit The Thvenin equivalent circuit seen looking into the emitter is useful in calculating  

E-print Network

Thévenin Emitter Circuit The Thévenin equivalent circuit seen looking into the emitter is useful with a resistor rie from the emitter node to signal ground. Fig. 1(a) shows the BJT symbol with a Thévenin source. With the emitter open circuited, we denote the emitter voltage by ve(oc). The voltage source in the Thévenin

Leach Jr.,W. Marshall

105

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

106

Coherent laser radar for vibrometry: robust design and adaptive signal processing  

Microsoft Academic Search

A coherent laser radar system based on semiconductor laser technology has been designed and built. The compact design and the absence of adjustments makes the system mechanically robust and easy to use. The present system has an output power of 50 mW and a line width of 280 kHz (HWHM). The laser radar system has been used in vibrometry measurements.

Ingmar G. Renhorn; Christer Karlsson; Dietmar Letalick; Mille C. Millnert; Remke Rutgers

1995-01-01

107

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

Microsoft Academic Search

Passive radars have been known to the scientific community since their first application as a system to detect bombers by means of shortwaves radiated by radio broadcasting towers in 1935, though they lately raised a renewed interest among researchers for some specific features that make them more appealing than classic active radar systems. In fact, having the transmitter and receiver

Antonio De Maio; Goffredo Foglia; Nicola Pasquino; Michele Vadursi

2009-01-01

108

High-Frequency Surface-Wave Radar Real Time Frequency Selecting Based on Frequency Randomly Hopping Signal  

Microsoft Academic Search

Serious radio interferences are distributed in the operating frequency band of High-frequency surface-wave radar (HFSWR) which makes it difficult to find silent bandwidth especially at night to work, the performance of HFSWR is decreased greatly. Frequency randomly hopping signal which breakthrough the restriction of continual spectrum has become an effective anti-jamming method. Based on the study of HF spectrum forecasting

Xu Liu; Changjun Yu

2008-01-01

109

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

110

Field emitter array memory device  

NASA Astrophysics Data System (ADS)

A field emitter array memory device having two or more collector electrodes, an extraction electrode, at least one deflector electrode, and at least one electron field emitter is disclosed. The field emitter array memory circuit has bias voltages for collector electrodes, for at least one deflector electrode and for the extraction electrode. In a preferred embodiment of the invention, first and second input signal voltages selectively applied to first and second deflector electrodes selectively switch the flow of electrons emitted from an electron field emitter from a first collector electrode to a second collector electrode and vice versa. A latched memory output is also included. Electron flow from the electron field emitter to one of the first and second collector electrodes is maintained until a signal voltage is applied to a deflector electrode to cause the electron flow to deflect from one collector electrode to the other collector electrode.

Gray, Henry F.

1993-07-01

111

Radar cross section  

Microsoft Academic Search

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

L. Nicolaescu; Teofil Oroian

2001-01-01

112

Selective Emitters  

NASA Technical Reports Server (NTRS)

This invention relates to a small particle selective emitter for converting thermal energy into narrow band radiation with high efficiency. The small particle selective emitter is used in combination with a photovoltaic array to provide a thermal to electrical energy conversion device. An energy conversion apparatus of this type is called a thermo-photovoltaic device. In the first embodiment, small diameter particles of a rare earth oxide are suspended in an inert gas enclosed between concentric cylinders. The rare earth oxides are used because they have the desired property of large emittance in a narrow wavelength band and small emittance outside the band. However, it should be emphasized that it is the smallness of the particles that enhances the radiation property. The small particle selective emitter is surrounded by a photovoltaic array. In an alternate embodiment, the small particle gas mixture is circulated through a thermal energy source. This thermal energy source can be a nuclear reactor, solar receiver, or combustor of a fossil fuel.

Chubb, Donald L. (inventor)

1992-01-01

113

Rain-Mapping Radar  

NASA Technical Reports Server (NTRS)

Orbiting radar system measures rates of rainfall from 0.5 to 60 mm/h. Radar waves scattered and absorbed by rainfall to extents depending on wavelength, polarization, rate of rainfall, and distribution of sizes and shapes of raindrops. Backscattered radar signal as function of length of path through rain used to infer detailed information about rain. Accumulated radar return signals processed into global maps of monthly average rainfall for use in climatological studies.

Im, K. E.; Li, F. K.; Wilson, W. J.; Rosing, D.

1988-01-01

114

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

115

FRESNEL program: fusion of radar and electro-optical signals for surveillance on land  

Microsoft Academic Search

Area surveillance for guarding and intruder detection with a combined camera radar sensor is considered. This specific sensor combination is attractive since complementary information is provided by the respective elements. Thus, a more complete description of objects of interest can be obtained. Several strategies to fuse the data are discussed. Results obtained with live experiments are presented. When compared to

Arne Theil; Leon Kester; Sebastiaan P. van den Broek; Philip van Dorp; Ronald van Sweeden

2001-01-01

116

The family of atomic functions and digital signal processing in synthetic aperture radar  

Microsoft Academic Search

The report consists of two parts. In the first part, the sampling analysis of weight windows is conducted on the basis of atomic functions (AF) and their application in problems of the classical method of synthetic aperture radar (SAR) is considered. The second part contains fundamentals of a modified method of synthetizing the aperture. The modified ambiguity function for different

V. F. Kravchenko; V. K. Volosyuk; V. V. Pavlikov

2007-01-01

117

Understanding the relation between the forest biomass and the radar backscattered signals  

Microsoft Academic Search

Numerical results are presented to improve understanding of the observed correlation of radar backscatter with canopy biomass in forests. The calculations employ a model developed by Karam el which is based on the solution of the vector radiative transfer equations and operates over a wide range of frequencies. The simulations use data collected over the Landes forest for canopy parameters.

M. A. Karam; D. M. LeVine; F. Amar; A. K. Fung; E. Mougin; A. Lopes

1993-01-01

118

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

USGS Publications Warehouse

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

Wildey, R. L.

1988-01-01

119

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

Microsoft Academic Search

When a meteoroid penetrates Earth's atmosphere, it forms a high-density ionized plasma column immersed in the ionosphere between approximately 70 and 140 km altitude. High-power, large-aperture (HPLA) radars detect nonspecular trails when VHF or UHF radio waves reflect off structures in a turbulent meteor trail. These trails persist from a few milliseconds to many minutes and the return from these

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

2008-01-01

120

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

121

Controlling radar signature  

SciTech Connect

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

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

1992-08-01

122

Controlling radar signature  

Microsoft Academic Search

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

Foulke

1992-01-01

123

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

124

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

NASA Technical Reports Server (NTRS)

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

Poultney, S. K.

1971-01-01

125

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

126

Emittance Exchange Results  

SciTech Connect

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

Fliller III,R.; Koeth, T.

2009-05-04

127

Emittance exchange results  

SciTech Connect

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

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

2009-09-01

128

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

Microsoft Academic Search

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

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

2011-01-01

129

Radar applications  

NASA Astrophysics Data System (ADS)

Papers are presented on air-traffic control radar, surveillance radar, missile guidance radar, and high-performance tactical three-dimensional radar. Also considered are the airborne early warning radar, the Foxhunter airborne intercept radar, and environmental remote sensing. Other topics include spaceborne SARs, the Pioneer Orbiter radar, and a bistatic pulse-Doppler intruder-detection radar.

Skolnik, Merrill I.

130

Radar applications  

Microsoft Academic Search

Papers are presented on air-traffic control radar, surveillance radar, missile guidance radar, and high-performance tactical three-dimensional radar. Also considered are the airborne early warning radar, the Foxhunter airborne intercept radar, and environmental remote sensing. Other topics include spaceborne SARs, the Pioneer Orbiter radar, and a bistatic pulse-Doppler intruder-detection radar.

Merrill I. Skolnik

1988-01-01

131

Asymmetrical field emitter  

DOEpatents

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

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

1995-01-01

132

Asymmetrical field emitter  

DOEpatents

A method is disclosed for providing a field emitter with an asymmetrical emitter structure having a very sharp tip in close proximity to its gate. One preferred embodiment of the present invention includes an asymmetrical emitter and a gate. The emitter having a tip and a side is coupled to a substrate. The gate is connected to a step in the substrate. The step has a top surface and a side wall that is substantially parallel to the side of the emitter. The tip of the emitter is in close proximity to the gate. The emitter is at an emitter potential, and the gate is at a gate potential such that with the two potentials at appropriate values, electrons are emitted from the emitter. In one embodiment, the gate is separated from the emitter by an oxide layer, and the emitter is etched anisotropically to form its tip and its asymmetrical structure. 17 figs.

Fleming, J.G.; Smith, B.K.

1995-10-10

133

Successful VSIPL Software Application Migration. A Case Study: NATO Seasparrow Illumination Radar Signal Processing.  

National Technical Information Service (NTIS)

An embedded weapon system signal processing software application involving 10K SLOC was converted from vendor proprietary middleware to that vendor's VSIPL implementation, deployed aboard US Navy surface combatants, and then ported without modification to...

D. Averill

2004-01-01

134

Near-field and timing effects in simulation of focused array radar signals from a mine in subsurface clutter  

NASA Astrophysics Data System (ADS)

In previous paper we discussed a frequency-domain simulation of GPR returns from buried mines in clutter due to random permittivity inhomogeneities, using a focused array radar systems. 3D image plots of the illuminated volume resulting from this simulation were presented and showed that mine buried a few inches deep in clay loam or sandy soil appears distinguishable from the clutter if the rms deviation of the permittivity from its mean is less than ten percent of the mean permittivity. The simulation is designed to be a forward model for signal processing algorithms for mine detection and location. Hence, both accuracy and running speed are important considerations. The code discussed in our previous paper is very fast, but contains approximations that compromise the accuracy of the electromagnetic modeling. The recent work on which the present paper is based addresses improvements in accuracy, emphasizing inclusion of near-field effects and more accurate depiction of the timing algorithm that is the basis of the focused array system. The result obtained from the more accurate algorithms require more running time to obtain but are still sufficiently fast for use as a forward model for signal processing.

Raemer, Harold R.; Rappaport, Carey M.; Miller, Eric L.

1999-08-01

135

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

NASA Astrophysics Data System (ADS)

Digital elevation models of glaciated terrain produced by the NASA/Jet Propulsion Laboratory (JPL) airborne interferometric synthetic-aperture radar (InSAR) instrument in Greenland and Alaska at the C- (5.6 cm wavelength) and L-band (24-cm) frequencies were compared with surface elevation measured from airborne laser altimetry to estimate the phase center of the interferometric depth, or penetration depth, ?p. On cold polar firn at Greenland summit, ?p = 92m at C- and 144m at L-band. On the exposed ice surface of Jakobshavn Isbrae, west Greenland, ?p = 12 m at C- and 33 m at L-band except on smooth, marginal ice where ?p=155 m. On colder marginal ice of northeast Greenland, ?p reaches 60 to 120 m at L-band. On the temperate ice of Brady Glacier, Alaska, ?p is 42 m at C-and 126 m at L-band, with little dependence on snow/ice conditions. The implications of the results on the scientific use of InSAR data over snow/ice terrain is discussed.

Rignot, Eric; Echelmeyer, Keith; Krabill, William

136

Removal of systematic seasonal atmospheric signal from interferometric synthetic aperture radar ground deformation time series  

NASA Astrophysics Data System (ADS)

Applying the Multidimensional Small Baseline Subset interferometric synthetic aperture radar algorithm to about 1500 Envisat and RADARSAT-2 interferograms spanning 2003-2013, we computed time series of ground deformation over Naples Bay Area in Italy. Two active volcanoes, Vesuvius and Campi Flegrei, are located in this area in close proximity to the densely populated city of Naples. For the first time, and with remarkable clarity, we observed decade-long elevation-dependent seasonal oscillations of the vertical displacement component with a peak-to-peak amplitude of up to 3.0 cm, substantially larger than the long-term deformation rate (<0.6 cm/yr). Analysis, utilizing surface weather and radiosonde data, linked observed oscillations with seasonal fluctuations of water vapor, air pressure, and temperature in the lower troposphere. The modeled correction is in a good agreement with observed results. The mean, absolute, and RMS differences are 0.014 cm, 0.073 cm, and 0.087 cm, respectively. Atmospherically corrected time series confirmed continuing subsidence at Vesuvius previously observed by geodetic techniques.

Samsonov, Sergey V.; Trishchenko, Alexander P.; Tiampo, Kristy; Gonzlez, Pablo J.; Zhang, Yu; Fernndez, Jos

2014-09-01

137

Doppler frequency in interplanetary radar and general relativity  

NASA Technical Reports Server (NTRS)

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

Mcvittie, G. C.

1972-01-01

138

Comparison of Target Detection Schemes in Doppler Radar with PSK Signals  

E-print Network

University of Library Studies and Information Technologies, Sofia, Bulgaria 2 igarvanov@yahoo.com ** Institute of Information and Communication Technologies, Sofia, Bulgaria 3 panayot.daskalov@mps.bg 4 petar of PSP (Phase Shift Keying) signals. Real records of moving people or bus on the background of woodland

Borissova, Daniela

139

A LBI Based Emitter Location Estimator with Platform Trajectory Optimality  

E-print Network

A LBI Based Emitter Location Estimator with Platform Trajectory Optimality Ran Ren and Mark L the location of a non- cooperative non-coherent emitter using intercepted signal measurements from a single. In this paper, we propose a single platform long baseline interferometry (LBI) based emitter location estimator

Fowler, Mark

140

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

141

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

142

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

143

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

144

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

145

IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 60, NO.2, FEBRUARY 2012 687 The MIMO Radar and Jammer Games  

E-print Network

, their interac- tion is modeled as a two-person zero-sum game. The mutual infor- mation criterion is used and measurement may enable the radar system a better capacity in characterizing the target in a contam- inated

Luh, Peter

146

Floating emitter solar cell  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

147

Radar absorbing materials used for target camouflage  

Microsoft Academic Search

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

I. NICOLAESCU

2006-01-01

148

Photonically Engineered Incandescent Emitter  

DOEpatents

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

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

2005-03-22

149

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

150

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

151

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

152

Spaceborne weather radar  

NASA Technical Reports Server (NTRS)

The present work on the development status of spaceborne weather radar systems and services discusses radar instrument complementarities, the current forms of equations for the characterization of such aspects of weather radar performance as surface and mirror-image returns, polarimetry, and Doppler considerations, and such essential factors in spaceborne weather radar design as frequency selection, scanning modes, and the application of SAR to rain detection. Attention is then given to radar signal absorption by the various atmospheric gases, rain drop size distribution and wind velocity determinations, and the characteristics of clouds, as well as the range of available estimation methods for backscattering, single- and dual-wavelength attenuation, and polarimetric and climatological characteristics.

Meneghini, Robert; Kozu, Toshiaki

1990-01-01

153

Micropower impulse radar imaging  

SciTech Connect

From designs developed at the Lawrence Livermore National Laboratory (LLNL) in radar and imaging technologies, there exists the potential for a variety of applications in both public and private sectors. Presently tests are being conducted for the detection of buried mines and the analysis of civil structures. These new systems use a patented ultra-wide band (impulse) radar technology known as Micropower Impulse Radar (GPR) imaging systems. LLNL has also developed signal processing software capable of producing 2-D and 3-D images of objects embedded in materials such as soil, wood and concrete. My assignment while at LLNL has focused on the testing of different radar configurations and applications, as well as assisting in the creation of computer algorithms which enable the radar to scan target areas of different geometeries.

Hall, M.S.

1995-11-01

154

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

Microsoft Academic Search

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

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

2010-01-01

155

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

SciTech Connect

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

Foxall, W; Vincent, P; Walter, W

1999-07-23

156

Ice Thickness and Basal Topography Near the Ross/Amundsen Ice Divide Revealed by Ground-based Radar and New Signal Processing  

NASA Astrophysics Data System (ADS)

The U.S. Science Plan for Deep Ice Coring in West Antarctica calls for a new ice core from a site near the Ross Sea/Amundsen Sea ice divide. The region is attractive because very thick ice in the region promises recovery of a long climate record with relatively high time resolution during the last glacial period. Ice thickness (together with accumulation rate history) is needed to estimate depth-age relationships for candidate core sites. However bed echoes from both airborne (Morse et al., Ann. Glac., v 35, 2002) and our ground-based radar profiles are often faint or not detected, especially in regions of very thick ice (up to 3500 m) that are preferred for potential core sites. Here we apply a combination of matched filtering and lateral averaging, which improves the signal-to-noise ratio of both englacial and bed echoes, to our 1.0 and 1.5MHz ground-based radar data collected in the vicinity of the western divide. Matched filtering requires a reflector model, which we derive from a strong, deep radar layer that is observed in nearly all transects. The signal model is consistent with bed echoes at sparse locations where the latter are reliable. Lateral averaging consists of coherent averaging at each point in the echogram, along lines of several slopes, followed by selection of the average of largest magnitude (constrained by an estimate of the maximum reflector slope). Lateral averaging is analogous to performing more stacking during acquisition to reveal fainter reflectors. Compared with data that have been processed by previous standard methods (eg. Gades et al., J. Glac. v 46, 2000), the new processing improves detection of the bed. Of particular interest is a profile along a flow line that crosses the ice divide at 42 km. The new processing clearly illuminates the bed at candidate site E at 15 km on the Ross Sea side of the divide; ice thickness there is 3460m. The bedrock divide is displaced 8 km west from the ice divide. No additional englacial layers were revealed by the processing in this case, and the deep radar stratigraphy is consistent with that found in a 1.5MHz transect that intersects the Byrd core. The basal topography near Site E is rough on the scale of 2-3km but the bed reflector itself is fairly coherent.

MacGregor, J. A.; Winebrenner, D. P.; Conway, H.; Sylvester, J.

2004-12-01

157

Applications of time-frequency processing to radar imaging  

Microsoft Academic Search

High resolution radar image is always demanded. To achieve high resolution, wideband signal and longer imaging time are required. However, due to time-varying behavior of returned radar signals and due to multiple backscattering behavior of targets, radar image resolution can be significantly degraded and images become blurred. The conventional radar processor uses the Fourier transform to retrieve Doppler information. In

Victor C. Chen

1996-01-01

158

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

159

A Kernel Density Window Clustering Algorithm for Radar Pulses  

Microsoft Academic Search

As radar signal environments become denser and more complex, the capability of high-speed and accurate signal analysis is required for ES (electronic warfare support) system to identify individual radar signals at real-time. In this paper, we propose the novel clustering algorithm of radar pulses to alleviate the load of signal analysis process and support reliable analysis. The proposed algorithm uses

Dong-Weon Lee; Jin-Woo Han; Kyu-Ha Song; Won Don Lee

2008-01-01

160

Laser Assisted Emittance Exchange  

SciTech Connect

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

Xiang, Dao; /SLAC

2012-06-11

161

Laser Assisted Emittance Exchange  

SciTech Connect

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

Dao Xiang [SLAC National Accelerator Laboratory, Menlo Park, CA, 94025 (United States)

2010-11-04

162

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

163

Fast Learning of Grammar Production Probabilities in Radar Electronic Support  

Microsoft Academic Search

Although stochastic context-free grammars (SCFG) appear promising for the recognition and threat assessment of complex radar emitters in radar electronic support (ES) systems, the computational requirements for learning their production rule probabilities can be onerous. The two most popular methods, the inside-outside (IO) algorithm and the Viterbi score (VS) algorithm, are both iterative. IO maximizes the likelihood of a training

Guillaume Latombe; Eric Granger; Fred A. Dilkes

2010-01-01

164

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

165

Planetary Radar Astronomy  

NASA Technical Reports Server (NTRS)

Radar is a powerful technique that has furnished otherwise unavailable information about solar system bodies for three decades. The advantages of radar in planetary astronomy result from: (1) the observer's control of all the attributes of the coherent signal used to illuminate the target, especially the wave form's time/frequency modulation and polarization; (2) the ability of radar to resolve objects spatially via measurements of the distribution of echo power in time delay and Doppler frequency; (3) the pronounced degree to which delay-Doppler measurements constrain orbits and spin vectors; and (4) centimeter-to-meter wavelengths, which easily penetrate optically opaque planetary clouds and cometary comae, permit investigation of near-surface macrostructure and bulk density, and are sensitive to high concentrations of metal or, in certain situations, ice. Planetary radar astronomy has primarily involved observations with Earth-based radar telescopes, but also includes some experiments with a spaceborne transmitter or receiver. In addition to providing a wealth of information about the geological and dynamical properties of asteroids, comets, the inner planets, and natural satellites, radar experiments have established the scale of the solar system, have contributed significantly to the accuracy of planetary ephemerides, and have helped to constrain theories of gravitation. This review outlines radar astronomical techniques and describes principal observational results.

Ostro, Steven J.

1993-01-01

166

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

167

Polarization diversity in radars  

NASA Astrophysics Data System (ADS)

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 polarization-based capabilities appear sufficiently assessed, such as adaptive polarization cancellation of clutter, chaff, and jamming. Polarization Doppler processing of dual-polarization radar signals, meteorologic applications, and polarization adaptation for target detection in the clear (in free space) are also examined.

Giuli, D.

1986-02-01

168

Imaging Radar for Ecosystem Studies  

NASA Technical Reports Server (NTRS)

Recently a number of satellites have been launched with radar sensors, thus expanding opportunities for global assessment. In this article we focus on the applications of imaging radar, which is a type of sensor that actively generates pulses of microwaves and, in the interval between sending pulses, records the returning signals reflected back to an antenna.

Waring, Richard H.; Way, JoBea; Hunt, E. Raymond J.; Morrissey, Leslie; Ranson, K. Jon; Weishampel, John F.; Oren, Ram; Franklin, Steven E.

1996-01-01

169

Outdoor Radar Mapping Using Measurement Likelihood Estimation  

E-print Network

Outdoor Radar Mapping Using Measurement Likelihood Estimation John Mullane, Martin D. Adams measure- ment models can be estimated directly. FMCW radar sensors are typically applied to outdoor. This is due to the radar's ability to penetrate dust, fog, and rain [2]. 2 Related Work Signal processing

Boyer, Edmond

170

Space-based radar clutter cancellation techniques  

Microsoft Academic Search

The ability of a space-based radar surveillance system to obtain target information from a clutter corrupted radar echo signal is dependent upon the clutter cancellation technique employed. In this paper, radar clutter is described using temporal probability models, spectral models, and average backscatter coefficient models. Capitalizing on the different spectral characteristics between clutter and targets, three representative Doppler clutter cancellation

J. Devenuto; K. G. Castor

1984-01-01

171

Implications of modeling clutter for radar simulations  

NASA Astrophysics Data System (ADS)

Methods for minimizing clutter returns which enhance the performance of surveillance radar systems are discussed. Included are methods which were implemented in the radar simulations currently in use at the Rome Air Development Center. The simulation output will include plots of raw clutter data for different mediums and clutter-to-noise ratios established after signal processing by a radar receiver.

Borek, Stanley E.; Pechewlys, Deborah A.

172

Atmospheric propagation effects on infrared radars  

Microsoft Academic Search

Compact coherent CO2 laser radars have the potential for greatly improved angle, range, and velocity resolution relative to their microwave radar counterparts. This research program was aimed at obtaining quantitative understanding of target reflection and atmospheric propagation effects on such laser radars through a combination of theory and experiments. Toward those ends, improved statistical signal models were developed, and corroborated

J. H. Shapiro

1984-01-01

173

Radar applications overview  

NASA Astrophysics Data System (ADS)

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

Greenspan, Marshall

1996-06-01

174

Cancer from internal emitters  

SciTech Connect

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

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

1995-10-01

175

Neural-network laser radar.  

PubMed

A laser radar whose resolution is greater than 1 m is reported. We present the radar results when they are used for such purposes as determining the size of a void inside a silicon wafer, profiling a cross-sectional pattern of an optical fiber, studying the birefringence of a lithium-niobate crystal, or finding a fault in an optical guide in an optical integrated-circuit wafer. Neural-network theory was used in processing the radar signal. Radar processing based on neural-network theory gave significantly superior resolution compared with Fourier-transform-based processing. PMID:20885600

Lizuka, K; Fujii, S

1994-05-01

176

Electrochemical formation of field emitters  

DOEpatents

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

Bernhardt, Anthony F. (Berkeley, CA)

1999-01-01

177

FACET Emittance Growth  

SciTech Connect

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

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

2011-04-05

178

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

179

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 been developed to en- hance the ground-penetrating radar (GPR) signal-to- clutter ratio for buried man radar, Excavation INTRODUCTION The value of ground-penetrating radar (GPR) as a sur- vey tool prior

Kansas, University of

180

The Newcastle meteor radar  

NASA Technical Reports Server (NTRS)

A brief history and development of the Newcastle Meteor Radar system is given. Also described are its geographical coordinates and its method of operation. The initial objective when the project was commenced was to develop an entirely digital analyzer capable of recognizing meteor echo signals and recording as many of their parameters as possible. This objective was achieved.

Keay, Colin

1987-01-01

181

Fabrication of Radar Absorbing Shells Made of Hybrid Composites and Evaluation of Radar Cross Section  

Microsoft Academic Search

** , Seoung-Bae Park ** and Myung-Shik Won *** ABSTRACT The avoidance of enemy's radar detection is very important issue in the modern electronic weapon system. Researchers have been studied to minimize reflected signals of radar. In this research, two types of radar absorbing structure (RAS), \\

Woo-Kyun Jung; Sung-Hoon Ahn; Bierng-Chearl Ahn

2005-01-01

182

Reappraisal of solid selective emitters  

SciTech Connect

New rare earth oxide emitters show greater efficiency than previous emitters. As a result, based on a simple model the efficiency of these emitters was calculated. Results indicate that the emission band of the selective emitter must be at relatively low energy (less than or equal to .52 eV) to obtain maximum efficiency at moderate emitter temperatures (less than or equal to 1500 K). Thus low bandgap energy PV materials are required to obtain an efficient thermophotovoltaic (TPV) system. Of the 4 specific rare earths (Nd, Ho, Er, Yb) studied Ho has the largest efficiency at moderate temperatures (72 percent at 1500 K). A comparison was made between a selective emitter TPV system and a TPV system that uses a thermal emitter plus a band pass filter to make the thermal emitter behave like a selective emitter. Results of the comparison indicate that only for very optimistic filter and thermal emitter properties will the filter TPV system have a greater efficiency than the selective emitter system.

Chubb, D.L.

1990-05-01

183

Reappraisal of solid selective emitters  

NASA Astrophysics Data System (ADS)

New rare earth oxide emitters show greater efficiency than previous emitters. As a result, based on a simple model the efficiency of these emitters was calculated. Results indicate that the emission band of the selective emitter must be at relatively low energy (less than or equal to .52 eV) to obtain maximum efficiency at moderate emitter temperatures (less than or equal to 1500 K). Thus, low bandgap energy PV materials are required to obtain an efficient thermophotovoltaic (TPV) system. Of the 4 specific rare earths (Nd, Ho, Er, Yb) studied, Ho has the largest efficiency at moderate temperatures (72 percent at 1500 K). A comparison was made between a selective emitter TPV system and a TPV system that uses a thermal emitter plus a band pass filter to make the thermal emitter behave like a selective emitter. Results of the comparison indicate that only for very optimistic filter and thermal emitter properties will the filter TPV system have a greater efficiency than the selective emitter system.

Chubb, Donald L.

184

Reappraisal of solid selective emitters  

NASA Technical Reports Server (NTRS)

New rare earth oxide emitters show greater efficiency than previous emitters. As a result, based on a simple model the efficiency of these emitters was calculated. Results indicate that the emission band of the selective emitter must be at relatively low energy (less than or equal to .52 eV) to obtain maximum efficiency at moderate emitter temperatures (less than or equal to 1500 K). Thus low bandgap energy PV materials are required to obtain an efficient thermophotovoltaic (TPV) system. Of the 4 specific rare earths (Nd, Ho, Er, Yb) studied Ho has the largest efficiency at moderate temperatures (72 percent at 1500 K). A comparison was made between a selective emitter TPV system and a TPV system that uses a thermal emitter plus a band pass filter to make the thermal emitter behave like a selective emitter. Results of the comparison indicate that only for very optimistic filter and thermal emitter properties will the filter TPV system have a greater efficiency than the selective emitter system.

Chubb, Donald L.

1990-01-01

185

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

186

Rapid prototyping of radar algorithms [Applications Corner  

E-print Network

Rapid prototyping of advanced signal processing algorithms is critical to developing new radars. Signal processing engineers usually use high level languages like MATLAB, IDL, or Python to develop advanced algorithms and ...

Reuther, Albert I.

187

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

188

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

189

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

190

Amorphous-diamond electron emitter  

DOEpatents

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

Falabella, Steven (Livermore, CA)

2001-01-01

191

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

192

Radar investigation of the Hockley salt dome  

E-print Network

surface. The salt face, however, is far from plane 24 and may cause much scattering of the radar wave and may cause the beamwidth to be much larger than that found above. All of the above facts can tend to make correlation of radar signals difficult... surface. The salt face, however, is far from plane 24 and may cause much scattering of the radar wave and may cause the beamwidth to be much larger than that found above. All of the above facts can tend to make correlation of radar signals difficult...

Hluchanek, James Andrew

2012-06-07

193

Millimeter radar improves target identification  

NASA Astrophysics Data System (ADS)

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

McAulay, Alastair D.

2011-06-01

194

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

195

Radar transponder operation with compensation for distortion due to amplitude modulation  

DOEpatents

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

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

2011-01-04

196

Radar Observations of Meteor Deceleration  

Microsoft Academic Search

By using a narrow-beam high-power radar operating at 68 cm it has been possible to detect meteors traveling radially toward the radar. In these observations the antenna is directed at the radiant point of an intense meteor shower, and the receiver is tuned to the expected Doppler-shifted signal. Because the actual Doppler shift can be measured with pre- cision, both

J. V. Evans

1966-01-01

197

Coherent laser radar in Europe  

Microsoft Academic Search

European work in coherent laser radar with 10 ?m and shorter wavelength lasers is reviewed. Fundamental aspects include heterodyne studies of signal statistics and fluctuations, and detailed experimental and theoretical work on signal amplification and autodyne arrangements with light reinjected into the laser cavity. Progress with lasers, detectors, and modulators has led to the development of several compact robust field

JOHN M. VAUGHAN; KURT OVE STEINVALL; CHRISTIAN WERNER; PIERRE HENRI FLAMANT

1996-01-01

198

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

199

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

200

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

Microsoft Academic Search

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

Jianguo He; Zhongliang Lu; Yi Su

1992-01-01

201

284 IEEE GEOSCIENCE AND REMOTE SENSING LETTERS, VOL. 2, NO. 3, JULY 2005 Suppressing Coherent Noise in Radar Applications  

E-print Network

no significant suppression was observed. Index Terms--Radar signal processing. I. INTRODUCTION WHILE MOST radar-based 150-MHz synthetic aperture radar (SAR). With a 4-m/s vehicle speed, a 5-kHz pulse repetition frequency

Kansas, University of

202

Exploring the limits of single emitter detection in fluorescence and extinction  

E-print Network

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

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

2008-08-25

203

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

204

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

205

Electro optical radar transmission chain modeling and simulation  

Microsoft Academic Search

In traditional radar systems, the use of electronic analog devices, such as mixers and oscillators, introduces some noise sources which complicate the realization of a completely digital radar systems. In fact, non linear behaviors of such systems as well as low Spurious Free Dynamic Range (SFDR) and low phase coherence, compromise radar performance in terms of detection and coherent signal

Francesco Laghezza; Amerigo Capria; Andrea Cacciamano; Fabrizio Berizzi; Paolo Ghelfi; Antonella Bogoni

2011-01-01

206

AIRBORNE RADAR SOUNDING OF THE GREENLAND ICE SHEET1  

Microsoft Academic Search

Radar sounding is a technique used in recent years to determine the thickness of ice sheets and glaciers. A radar signal is transmitted through ice, a dielectric, is reflected from the bottom, and is received at some time after its transmission. The length of time which the radar pulse spends in the ice, the so-called \\

EDMUND P. PAWLOWICZ

207

A system model and inversion for synthetic aperture radar imaging  

Microsoft Academic Search

A system model and its corresponding inversion for synthetic aperture radar imaging are presented. The system model incorporates the spherical nature of a radar's radiation pattern at far field. The inverse method based on this model integrates the recorded signals at various coordinates of a translational radar (linear array) via a spatial Fourier transform. The transformed data are shown to

M. Soumekh

1990-01-01

208

Target identification performance improvement from enhanced HRR radar clutter suppression  

Microsoft Academic Search

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

Bart Kahler; Erik Blasch

2009-01-01

209

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

210

The Patriot radar in tactical air defense  

NASA Astrophysics Data System (ADS)

The Patriot radar is a C-band, phased-array, multifunction radar that, under the control of the weapon control computer in the engagement control station, performs target search and track; missile search, track, and communications during midcourse guidance; and target-via-missile terminal guidance. This paper describes the functions the radar performs and provides descriptions of the subsystems. The use of a multichannel, multifunction receiver and digital signal processor is emphasized to demonstrate the control and processing for multiple radar actions required to support the tactical air defense mission. A summary of results of an extensive test program at the White Sands Missile Range is presented.

Carey, David R.; Evans, William

1988-05-01

211

First radar echoes from cumulus clouds  

SciTech Connect

In attempting to use centimeter-wavelength radars to investigate the early stage of precipitation formation in clouds, 'mantle echoes' are rediscovered and shown to come mostly from scattering by small-scale variations in refractive index, a Bragg kind of scattering mechanism. This limits the usefulness of single-wavelength radar for studies of hydrometeor growth, according to data on summer cumulus clouds in North Dakota, Hawaii, and Florida, to values of reflectivity factor above about 10 dBZe with 10-cm radar, 0 dBZe with 5-cm radar, and -10 dBZe with 3-cm radar. These are limits at or above which the backscattered radar signal from the kinds of clouds observed can be assumed to be almost entirely from hydrometeors or (rarely) other particulate material such as insects. Dual-wavelength radar data can provide the desired information about hydrometeors at very low reflectivity levels if assumptions can be made about the inhomogeneities responsible for the Bragg scattering. The Bragg scattering signal itself probably will be a useful way to probe inhomogeneities one-half the radar wavelength in scale for studying cloud entrainment and mixing processes. However, this use is possible only before scattering from hydrometeors dominates the radar return. 25 refs.

Knight, C.A.; Miller, L.J. (NCAR, Boulder, CO (United States))

1993-02-01

212

First radar echoes from cumulus clouds  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

213

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

214

Fly eye radar or micro-radar sensor technology  

NASA Astrophysics Data System (ADS)

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

Molchanov, Pavlo; Asmolova, Olga

2014-05-01

215

Field-emitter arrays for vacuum microelectronics  

Microsoft Academic Search

An ongoing program on microfabricated field-emitter arrays has produced a gated field-emitter tip structure with submicrometer dimensions and techniques for fabricating emitter arrays with tip packaging densities of up to 1.5107 tips\\/cm2. Arrays have been fabricated over areas varying from a few micrometers up to 13 cm in diameter. Very small overall emitter size, materials selection, and rigorous emitter-tip processing

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

1991-01-01

216

Two-dimensional adaptive processing for ionospheric clutter mitigation in High Frequency Surface Wave Radar  

Microsoft Academic Search

High Frequency Surface Wave Radar (HFSWR) is a technology used for over-the-horizon detection of ocean vessels. This radar exploits the diffraction of electromagnetic waves around the curved surface of the Earth. To minimize the attenuation of the diffracted waves, the radar must operate at frequencies in the lower part of the high frequency (HF) band. However, radar signals at these

Ryan J. Riddolls; Raviraj S. Adve

2009-01-01

217

Ship Detection Performance of a High Frequency Hybrid Sky-Surface Wave Radar  

Microsoft Academic Search

Abstract A high frequency radar conguration,consisting of a skywave transmit path and a surface wave receive path is presented and analyzed. Limits on the radar resolution capability are determined using an analytic ray tracing formulation of radar signal propagation in an ionospheric plasma. This resolution is then substituted into the radar equation. It is found that the detection of low-velocity

R. J. Riddolls

2007-01-01

218

Multichannel Receiver Design, Instrumentation, and First Results at the National Weather Radar Testbed  

Microsoft Academic Search

When the National Weather Radar Testbed (NWRT) was installed in 2004, a single-channel digital receiver was implemented so that the radar could mimic typical Weather Surveillance Radar (WSR) version 1988 Doppler (WSR-88D) capability. This, however, left unused eight other channels, built into the antenna. This paper describes the hardware instrumentation of a recently completed project that digitizes the radar signals

Mark Yeary; Gerald Crain; Allen Zahrai; Christopher D. Curtis; John Meier; Redmond Kelley; Igor R. Ivic; Robert D. Palmer; Richard J. Doviak; G. Zhang; Tian-You Yu

2012-01-01

219

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

220

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

221

Waveform error analysis for bistatic synthetic aperture radar systems  

NASA Astrophysics Data System (ADS)

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

Adams, J. W.; Schifani, T. M.

222

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

E-print Network

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

Sawa Manoff

2005-05-12

223

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

224

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

225

Emittance correction of photocathode gun  

SciTech Connect

The standard emittance calculation removes linear correlations between transverse displacement r and the divergence r{prime}. Higher order correlations remain and they are responsible for a substantial area in phase space which corresponds to the calculated emittance. Time dependent correlations are identified and different procedures (transverse and longitudinal laser shaping, rf quadrulope) are proposed to remove them. The Brookhaven National Laboratory rf gun has been studied; however, in order to more clearly demonstrate the desired effects, the accelerating field and bunch length have been assumed to be more optimistic than the present operating values. This approach reduces the realizable emittance by a factor of 5 with respect to the value before the correction. 9 refs., 5 figs., 1 tab

Gallardo, J.C. (Brookhaven National Lab., Upton, NY (USA)); Palmer, R.B. (Brookhaven National Lab., Upton, NY (USA) Stanford Linear Accelerator Center, Menlo Park, CA (USA))

1990-01-01

226

Transverse Emittance Measurement at REX ISOLDE  

E-print Network

The transverse emittance of REX-ISOLDE beams has been measured at 0.3 MeV/u (RFQ energy) and 2.85 MeV/u (maximum energy). This document compares RMS emittances measured with a slit-grid emittance meter (NTG emittance-meter) and RMS emittances measured with the quadrupole-scan method or three-gradient method. The results are compared with other measurements made with the slitgrid emittance meter in 2006 and 2008. The data treatment process is also described.

Lanaia, D; Voulot, D

2014-01-01

227

A continuous-wave (CW) radar for gait analysis  

Microsoft Academic Search

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

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

2001-01-01

228

Direct Observations of Coherent Backscatter of Radar Waves in Precipitation A. R. JAMESON  

E-print Network

Direct Observations of Coherent Backscatter of Radar Waves in Precipitation A. R. JAMESON RJH the authors now present direct observations of radar coherent backscattered signals in precipitation, hereafter JK10a) the presence of radar coherent signals backscattered by precipitation was inferred from

Kostinski, Alex

229

Initialization Analysis of IIR Ground Clutter Filter in Doppler Weather Radar  

Microsoft Academic Search

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

Yuchun Gao; Yan Liu; He Jianxin

2007-01-01

230

Clutter cancellation techniques for use in a space-based radar system  

Microsoft Academic Search

The ability of a space-based radar surveillance system to obtain target information from a clutter corrupted radar echo signal is dependent on the clutter cancellation technique employed. To thoroughly understand the nature of clutter so as to efficiently and effectively design and develop clutter cancellation techniques, fundamental mathematical relationships dealing with radar signal representation, probability theory, detection and estimation theory

J. Devenuto

1983-01-01

231

Passive Tracking and Locating Radar Based on Double GSM Base Stations  

Microsoft Academic Search

Passive radar is a kind of that without its own transmitter and receive the thermal emission energy of an object or its source of microwave energy reflected from the radar to detect targets. The widely distributed GSM base station signals have GMSK frequency modulation characteristics, these signals can be used as a passive radar radiation source for its ambiguity function

Zhang Ping-chuan; Li Bu-yin

2010-01-01

232

Millimeter-Wave Concurrent Dual-Band BiCMOS RFIC Transmitter for Radar and Communication Systems  

E-print Network

in radio astronomy and synthetic aperture radar (SAR) applications [14]. Receiver The radar receivers amplify, filter, and down-convert the received signal to the intermediate frequency (IF) or baseband signal, from which the target can be correctly... in radio astronomy and synthetic aperture radar (SAR) applications [14]. Receiver The radar receivers amplify, filter, and down-convert the received signal to the intermediate frequency (IF) or baseband signal, from which the target can be correctly...

Huynh, Cuong Phu Minh 1976-

2012-11-21

233

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

234

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

235

Airborne pulse Doppler radar. Part 3: Performance estimation  

NASA Astrophysics Data System (ADS)

Techniques and methods which can be used to obtain an indication of the performance capabilities of a pulse Doppler radar, are analyzed. The effects of target fluctuation, clutter characteristics, detailed radar parameters and radar-target encounter geometry, are discussed. The basic detection theory, the analysis of signal-to-noise ratio, the determination of the target detectability, the applications of the radar equation, and the operating limitations (other than thermal noise), are outlined. It is concluded that the prediction of radar maximum range performance can never be guaranteed to be accurate in the exact sense, and precise agreement between prediction and the results of limited experimental measurement is not to be expected.

Robertson, J. C.

1989-04-01

236

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

237

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

238

Radar electronic warfare  

Microsoft Academic Search

An overview of radar and electronic warfare is given. Definitions, common terms, and principles of radar and electronic warfare, and simple analyses of interactions between radar systems and electronic countermeasures (ECM) are presented. Electronic counter-countermeasure and electronic support measures are discussed. Background material in mathematics, electromagnetics, and probability necessary for an understanding of radar and electronic warfare is given and

August Golden Jr.

1987-01-01

239

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

240

Optimized aperiodic highly directional narrowband infrared emitters  

E-print Network

Optimized aperiodic highly directional narrowband infrared emitters Christopher H. Granier,1 as narrowband, highly directional thermal infrared emitters for both TE and TM polarizations. These aperiodic-infinite tungsten substrate exhibit extremely high emittance peaked around the wavelength at which the structures

Veronis, Georgios

241

A quantitative study of emitter ballasting  

Microsoft Academic Search

A theoretical and experimental study is carried out to quantitatively analyze the effect of emitter ballasting on thermal instabilities in high power density transistors. The analysis includes factors such as thermal resistance, emitter and base resistances, collector dissipation, etc., affecting thermal runaway. In particular, numerical computations are presented to describe current-voltage characteristics as they relate to thermal instability with emitter

R. P. Arnold; D. S. Zoroglu

1974-01-01

242

Sensor-Emitter Simulation Description Adam Campbell  

E-print Network

Sensor-Emitter Simulation Description Adam Campbell July 7, 2009 1 #12;Contents 1 Introduction 3 1 DISCRETIZATION and EMITTER DISCRETIZATION . . . . . . . . . . . . . . . . . 4 2.1.4 BACKGROUND COLOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.3.2 SENSOR COLOR i and EMITTER COLOR i . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2

Stanley, Kenneth O.

243

Spectroscopic Properties Unique to Nano-Emitters  

Microsoft Academic Search

The spectral position of light emission from an individual carbon nanotube is shown to depend on the location of the nanotube within the focal spot, while no such effect is present for macroscopic emitters. In addition, in contrast to macroscopic emitters, the measured line width from the nanotube emitter is independent of spectrometer entrance slit width. The effects are general

Andrew G. Walsh; Wolfgang Bacsa; A. Nickolas Vamivakas; Anna K. Swan

2008-01-01

244

Radar shadow and superresolution features for automatic recognition of MSTAR targets  

E-print Network

resolution (HRR) radar signals generally use as their primary input either a synthetic aperture radar (SAR) image or else a sequence of one or more one-dimensional HRR range profiles. The image-based approaches

Brookes, Mike

245

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

National Technical Information Service (NTIS)

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

R. A. Diaz

2004-01-01

246

Abstract-This paper presents a Doppler radar system used to detect the heartbeat signal from a distance of one meter. The  

E-print Network

and heart rate variability are extracted and compared to a simultaneous ECG signal. Keywords: microwave heartbeat rate and Heart Rate Variability (HRV) are extracted and compared to the values obtained by the ECG of the heartbeat rate and the Heart Rate Variability (HRV) for both original and smoothed signals. Section V

Paris-Sud XI, Université de

247

Detecting and Mitigating Wind Turbine Clutter for Airspace Radar Systems  

PubMed Central

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

2013-01-01

248

Space-based radar clutter cancellation techniques  

NASA Astrophysics Data System (ADS)

The ability of a space-based radar surveillance system to obtain target information from a clutter corrupted radar echo signal is dependent upon the clutter cancellation technique employed. In this paper, radar clutter is described using temporal probability models, spectral models, and average backscatter coefficient models. Capitalizing on the different spectral characteristics between clutter and targets, three representative Doppler clutter cancellation schemes are described. Using the clutter models and cancellation schemes described, the clutter attenuation factors for the various cancellation methods against different backgrounds are computed to evaluate the clutter cancellation ability of different cancellation schemes.

Devenuto, J.; Castor, K. G.

249

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

250

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

251

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

PubMed Central

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

2008-01-01

252

Non-locality from N > 2 Independent Single Photon Emitters  

E-print Network

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 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.

C. Thiel; R. Wiegner; J. von Zanthier; G. S. Agarwal

2010-05-23

253

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

254

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

255

Fast Incremental Techniques for Learning Production Rule Probabilities in Radar Electronic Support  

Microsoft Academic Search

Although Stochastic context-free grammars appear promising for recognition of radar emitters, and for estimation of their respective level of threat in radar electronic support systems, well-known techniques for learning their production rule probabilities are computationally demanding. In this paper, three fast incremental alternatives, called graphical EM (gEM), tree scanning (TS), and HOLA, are compared from several perspectives - perplexity, generalization

Guillaume Latombe; Eric Granger; Fred A. Dilkes

2006-01-01

256

Radar image of Rio Sao Francisco, Brazil  

NASA Technical Reports Server (NTRS)

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

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

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

2000-01-01

257

Radar electronic warfare  

NASA Astrophysics Data System (ADS)

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

Golden, August, Jr.

258

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

NASA Astrophysics Data System (ADS)

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

Parent, Jacques

1989-09-01

259

Transverse Emittance Reduction with Tapered Foil  

SciTech Connect

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

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

2011-12-09

260

Soviet oceanographic synthetic aperture radar (SAR) research  

SciTech Connect

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

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

1991-01-01

261

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

262

Influence of ionospheric irregularities on the form of radio signal scattering spectrum in over-the-horizon radar sounding of the rough sea surface  

NASA Astrophysics Data System (ADS)

This paper is concerned with the backscattering of HF radio waves from the rough sea surface, which have propagated through the ionosphere with random large-scale irregularities. For the sake of simplicity, it is assumed in calculations that the rough sea surface is a perfectly conducting surface with the known Philips power spectrum of irregularities. Ionospheric irregularities of a random medium that are isotropic and single-scale ones, with a Gaussian spectrum, are considered within the limits of the hypothesis of frozen-in irregularities. Within the first approximation of perturbation theory, using, as the incident wave and the Green function, their geometrical-optics approximations, we obtained the expression for the backscattering spectrum of the ionospheric chirp radio signal with a Gaussian envelope. The expression involves the parameters of the receive-transmit antenna, the signal, the propagation medium, and of the scattering surface. Numerical simulation was used to investigate the influence of all the above-mentioned parameters on the backscattering spectrum. It is shown that travel of ionospheric irregularities has the largest influence on the scattering spectrum, the signal parameters mainly determine the size of the scattering area in the range, and the form of the coherent integration window determines the form of the received signal and can distort it.

Ignatenko, M. V.; Tinin, M. V.

2003-07-01

263

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

264

Hail detection using S-band dual polarization radar  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

265

Detection of Shallowly Buried Objects Using Impulse Radar  

Microsoft Academic Search

The impulse radar has shown promising results for detecting buriedobjects, even non-metallic ones. One problem with ground penetratingradars is the strong backscattered signal from the ground surface.If the object is buried deeply below the surface this is no problem sincethe backscattered signal from the surface will arrive earlier than thetarget signal and we only have to gate the time signal.

H. Brunzell

1996-01-01

266

Applications of high-frequency radar  

NASA Astrophysics Data System (ADS)

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

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

1998-07-01

267

Pedestrian recognition using automotive radar sensors  

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

268

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

269

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

270

Emittance Growth in the NLCTA First Chicane  

SciTech Connect

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

Sun, Yipeng; Adolphsen, Chris; /SLAC

2011-08-19

271

Radar augmentation device  

NASA Technical Reports Server (NTRS)

The radar augmentation device (RAD) serves to increase the radar response of a target body and thus expedite radar acquisition. The design and development of the RAD are discussed with particular emphasis on technical problems that were encountered and solved. Discussions of the mode of operation of the RAD and the ground test history are also included.

Riedel, J. K.

1972-01-01

272

Micropower impulse radar  

Microsoft Academic Search

Invented and developed at Lawrence Livermore National Laboratory is an inexpensive and highly sensitive, low-power radar system that produces and samples extremely short pulses of energy at the rate of 2 million per second. Called micropower impulse radar (MIR), it can detect objects at a greater variety of distances with greater sensitivity than conventional radar. Its origins in the Laboratory`s

S. Azevedo; T. E. McEwan

1996-01-01

273

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

274

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

275

A Fiber-Optic-Based 1550-nm Laser Radar Altimeter with RF Pulse Compression Christopher Allen, Sivaprasad Gogineni  

E-print Network

A Fiber-Optic-Based 1550-nm Laser Radar Altimeter with RF Pulse Compression Christopher Allen and couples the backscattered signal into a single-mode optical fiber prior to photodetection. The RF signal of modern radar processing techniques with fiber-optic technology in a laser radar. This is the first stage

Kansas, University of

276

The Atmospheric Radiation Measurement Program Cloud Profiling Radars: Second-Generation Sampling Strategies, Processing, and Cloud Data Products  

Microsoft Academic Search

The United States Department of Energy Atmospheric Radiation Measurement program operates millimeter-wavelength cloud radars in several climatologically distinct regions. The digital signal processors for these radars were recently upgraded and allow for enhancements in the operational parameters running on them. Recent evaluations of millimeter-wavelength cloud radar signal processing performance relative to the range of cloud dynamical and microphysical conditions encountered

Pavlos Kollias; Eugene E. Clothiaux; Mark A. Miller; Edward P. Luke; Karen L. Johnson; Kenneth P. Moran; Kevin B. Widener; Bruce A. Albrecht

2007-01-01

277

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

278

Ionospheric Clutter Suppression in HF Surface Wave Radar  

Microsoft Academic Search

The ionospheric clutter has been proved to be one of the dominant clutters degrading the performance of the HF surface-wave radar (HFSWR) severely, so suppressing the ionospheric clutter is a vital part of radar signal processing sequence. In this paper, the spatial characteristics of the ionospheric clutter in a planar array are analyzed, then a new orthogonal projection method with

M. Wu; B. Y. Wen; H. Zhou

2009-01-01

279

The case for bistatic HF surface wave radar  

Microsoft Academic Search

This paper examines some of the issues associated with implementation of HF surface wave radars (HFSWR) in bistatic and monostatic configurations. Most HFSWRs deployed in the field are pseudo-monostatic although they may not be optimum for all deployments. Radar transmitter spectral characteristics, detection performance based on received signal strength and site selection criteria are considered in this paper for both

P. Marrone; P. Edwards

2008-01-01

280

Effects of Water and Ice Layer on Automotive Radar  

Microsoft Academic Search

Short AbstractThis experiment is carried out at the ,Robert Bosch GmbH, to analyse the signal degradation of millimeter wave radar Sensors in adverse ,weather conditions. It reveals that, the existence of water layer on the surface of antenna lens or its radome ,is the ,main ,cause for performance ,limitation of automotive radar sensors and provides information to identify such phenomena.

Alebel Arage; Wolf M. Steffens; Goetz Kuehnle; Rolf Jakoby

281

Time-frequency radar processing for meteor detection  

Microsoft Academic Search

In this paper, we present signal processing techniques to detect meteor returns from Arecibo Observatory 430-MHz UHF radar data. We exploit the characteristics of the transmit waveform in the frequency domain as well as in the time domain. Two detection methods are investigated. First, when a meteor is present in the radar return over several interpulse periods, there will be

Chun-Hsien Wen; J. F. Doherty; J. D. Mathews

2004-01-01

282

Independent evaluation of the ability of spaceborne radar and lidar  

E-print Network

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

Hogan, Robin

283

Reconnaissance with ultra wideband UHF synthetic aperture radar  

Microsoft Academic Search

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

MEHRDAD SOUMEKH

1995-01-01

284

K-Distribution and Polarimetric Terrain Radar Clutter  

Microsoft Academic Search

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

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

1989-01-01

285

Chemical regeneration of emitter surface increases thermionic diode life  

NASA Technical Reports Server (NTRS)

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

Breiteieser, R.

1966-01-01

286

Doppler Radar Detection of Mechanically Resonating Objects Jason P. Stockman* (nl) and Kamal Sarabandi (1)  

E-print Network

, plant matter, rocks, and other clutter that cause false alarms for GPR. An object is distinguished based on the Doppler signature imparted to radar signals scattering offthe object's vibrating surface. The present are measured using a CW radar system. When the object surface retreats from the radar, the carrier is slightly

Sarabandi, Kamal

287

ON PARTICLE FILTERS FOR LANDMINE DETECTION USING IMPULSE GROUND PENETRATING RADAR  

E-print Network

ON PARTICLE FILTERS FOR LANDMINE DETECTION USING IMPULSE GROUND PENETRATING RADAR William Ng detection based on ground penetrating radar (GPR) signals using sequential Monte Carlo (SMC) methods. Since resolution and excellent de- tection of metallic and nonmetallic objects, ground penetrating radar (GPR) has

So, Hing-Cheung

288

Improved Hydrogeophysical Parameter Estimation from Empirical Mode Decomposition Processed Ground Penetrating Radar Data  

E-print Network

Penetrating Radar Data Adrian D. Addison, Bradley M. Battista and Camelia C. Knapp Department of Geological penetrating radar (GPR) as an exploration tool. Improvements in signal processing are expected to further for quantitative analyses. Introduction In the field of hydrogeophysics, ground penetrat- ing radar (GPR) is just

Knapp, Camelia Cristina

289

Effects of magnetite on high-frequency ground-penetrating radar Remke L. Van Dam1  

E-print Network

Effects of magnetite on high-frequency ground-penetrating radar Remke L. Van Dam1 , Jan M. H to understand the effects of magnetite for ground-penetrating radar (GPR) characterization of the shallow of ferrimagnetic material on ground-penetrating radar (GPR) signal performance. This interest has been driven

Borchers, Brian

290

Employing PML Absorbers in the Design and Simulation of Ground Penetrating Radars  

E-print Network

to simulate an absorbing material inside the FDTD computational domain. T R S R R D S RADAR UNIT AIR GROUNDEmploying PML Absorbers in the Design and Simulation of Ground Penetrating Radars Levent Gurel: Total signals at the receiver when the radar unit is modeled as in Fig. 2b with no absorbers. The depth

Gürel, Levent

291

Annual energy window performance vs. glazing thermal emittance the relevance of very low emittance values  

Microsoft Academic Search

This paper investigates the heating and cooling energy impact of low thermal emittance values for architectural glazings. The importance of low emittance values and the sensitivity for small changes in the emittance is investigated for three very different climates and for two different types of buildings. Our results imply that minor changes in the parameter values lead to very small

J. Karlsson; A Roos

2001-01-01

292

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

E-print Network

Emitter Localization and Visualization (ELVIS): A Backward Ray Tracing Algorithm for Locating Emitters Aliye ¨Ozge Kaya Larry Greenstein WINLAB, Rutgers University {ozgekaya, ljg is unreliable in most buildings. Therefore new technologies are needed to localize the emitters inside buildings

293

Comparison between UWB and CW radar sensors for breath activity monitoring  

NASA Astrophysics Data System (ADS)

In this paper the ability of four radar sensors in detecting breath activity has been tested. In particular, range gating UWB, CMOS UWB, CW phase detecting, and FMCW radars have taken into account. Considering a realistic scenario, the radar antenna has been pointed towards the thorax of a breathing subject and the recorded signals have been compared with those of a piezoelectric belt placed around the thorax. Then the ability of the radars in detecting small movements has been tested by means of an oscillating copper plate placed at various distances from the radar antenna. All the considered radars were able to detect the plate movements with a distance-dependent resolution.

Pisa, Stefano; Bernardi, Paolo; Cicchetti, Renato; Giusto, Roberto; Pittella, Erika; Piuzzi, Emanuele; Testa, Orlandino

2014-05-01

294

Cloud and Precipitation Radar  

NASA Astrophysics Data System (ADS)

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

Hagen, Martin; Hller, Hartmut; Schmidt, Kersten

295

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

296

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

297

Modern Radar Techniques for Geophysical Applications: Two Examples  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

298

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

299

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

300

Carbon nanotube films as electron field emitters  

Microsoft Academic Search

Carbon nanotubes have been recognized as one of the most promising electron field emitters currently available. We review the state of the art of current research on the electron field emission properties of carbon nanotube films and present recent results outlining their potential as field emitters as well as illustrating some current concerns in the research field.

Jean-Marc Bonard; Mirko Croci; Christian Klinke; Ralph Kurt; Olivier Noury; Nicolas Weiss

2002-01-01

301

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

302

Emitter Follower Amplifier DC Analysis FREQ = 10000  

E-print Network

Emitter Follower Amplifier ­ DC Analysis C3 1n R1 30k Vcc 20Vdc C1 1n RL 500 Re 40k 0 Re1 200 Q2 Q2.97757mA re = 26/ IE = 26.597 (used later in ac analysis) For the emitter follower circuit and neglecting

Allen, Gale

303

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

304

Application of a differential reflectivity technique to the EDOP radar in ground-based operation  

Microsoft Academic Search

This paper discusses the modification of a single-frequency Doppler radar (9.6 GHz) to accommodate dual-frequency operation for the study of the microphysical character of precipitation. The modification involves the ER-2 Doppler radar (EDOP), an airborne, meteorological research radar of the NASA\\/Goddard Space Flight Center. Radar operation is modified to provide reflectivity signals at two distinct frequencies at 9% separation. Differential

S. W. Bidwell; R. Meneghini; L. Liao; R. F. Rincon; G. M. Heymsfield

2000-01-01

305

Observation of Dynamic Emittance at CESR with CLEO  

E-print Network

Observation of Dynamic Emittance at CESR with CLEO Katherine Korbiak Departments of Chemistry and Physics, Wayne State University, Detroit, Michigan, 48202 Abstract Dynamic emittance has been spread of the luminous region. Using these predicted resolutions, the beta and the emittance

Cinabro, David

306

Stentor long range ground surveillance radar  

NASA Astrophysics Data System (ADS)

The Stentor radar is designed to detect, recognize, and locate moving targets such as infantry, ground vehicles, helicopters, low-flying aircraft, and boats. It can be transported without difficulty and operated by unskilled personnel. Stentor's longer range gives both an earlier warning time and a reinforced detection capability at shorter distances, even on very small targets. It is a pulsed radar that eliminates fixed echoes by coherent reception and Doppler filtering. The antenna unit incorporates all the parts necessary for the transmission, reception, and processing of the radar signal. It comprises six distinct subassemblies: a conventional antenna, an antenna-bearing mechanism, a transmitter-receiver unit, a signal-processing unit, a power supply module, and a tripod for mounting the antenna unit.

Stoll, P.

307

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

308

FREQUENCY DEPENDENT ATTENUATION ANALYSIS OF GROUND-PENETRATING RADAR DATA  

E-print Network

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

Barrash, Warren

309

Interpolation of the Radial Velocity Data from Coastal HF Radars.  

National Technical Information Service (NTIS)

In recent years, monitoring nearshore surface currents became an important application of the high-frequency radar (HFR) technology. The Doppler shifts of backscattered radio signals from surface waves provide the surface velocity component in the directi...

A. Sentchev, M. Yaremchuk

2013-01-01

310

New approach to obtain boron selective emitters  

SciTech Connect

Selective emitters, used in high efficiency solar cells, need a series of oxidations and photolithographic steps that render the process more expensive. In this paper, a new way to make selective emitters using boron is presented. The main feature of this approach is to save oxide growths and photolithographic processes and it is based on the property of boron doped silicon surfaces to be resistant to anisotropic etchings like the one performed during the texturization. Using this characteristic of boron emitter surfaces, the authors can obtain a highly doped emitter under metal grid and simultaneously a shield to avoid texture on these surfaces. First cells were processed and short wavelength response of p{sup +}nn{sup +} solar cells was enhanced by using lightly doped boron emitters in the uncovered area.

Moehlecke, A.; Luque, A. [ETSI Telecomunicacion, Madrid (Spain). Inst. de Energia Solar

1994-12-31

311

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

312

Low emittance lattice cell withlarge dynamic aperture  

E-print Network

Compact low emittance lattice cell providing large dynamic aperture is essentual for development of extremely low (pm range) emittance storage rings. As it is well known, a pair of identical sextupoles connected by a minus-identy matrix transformer in ideal case of kick-like magnets provides infinite dynamic aperture. Though the finite sextupole length degrades the aperture, it is still large enough, and in this report we discuss development of the low emittance lattice cell providing the -I condition for both horizontal and vertical chromatic sextupoles. Such cell can be used as a module for lattices of different emittance and length. As an example we develop a 3 GeV 10 pm emittance storage ring and study its transverse dynamic aperture.

Bogomyagkov, A; Piminov, P

2014-01-01

313

Basic characteristics of FM-CW radar systems  

NASA Astrophysics Data System (ADS)

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

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

1986-07-01

314

Microlensless Interdigitated Photoconductive Terahertz Emitters  

E-print Network

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

Singh, Abhishek

2014-01-01

315

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

316

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

317

Generating nonlinear FM chirp waveforms for radar.  

SciTech Connect

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

Doerry, Armin Walter

2006-09-01

318

Orbit determination using synthetic aperture radar  

Microsoft Academic Search

The use of synthetic aperture radar (SAR) images to estimate orbital parameters is studied. The SAR image formation process which requires the ability to repeatedly transmit identical signals and accurately sense the return echoes from a region of terrain is described. The orbit determination capabilities of the SAR system's observables are investigated. Five SAR observations were collected from a simulated

W. L. Taber; S. P. Synnott; J. E. Riedel

1986-01-01

319

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

320

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

321

Beijing MST radar: Overview and preliminary results  

NASA Astrophysics Data System (ADS)

As one of the main facilities of so-called China Meridian Project which is focusing on the monitoring solar-terrestrial link and space weather, as well as sun-earth climate connection study, Beijing MST radar has been completed in the middle of 2011 and started its quasi-continuous operational observation since the end of 2011. Beijing MST radar is located in IAP's field observatory (39.4 N,117.0 E) which is a large scale full coherent VHF Doppler radar, with antenna area 9,110 m^2, power-aperture product 3.1108 W.m^2. It's antenna array is consisted of 2424 three element YAGI antenna with square digital active phased array, with beam width equal to or less than 4.5 degree and active five antenna beam azimuth directions and zenith angle ranging from zenith to 20 degree with 1 degree steps. Also the radar uses direct digital receivers and high speed signal processing system. The expected observation altitude is 3-25 km and 60-90 km, for which low, middle and high observation modes can be selected with different vertical resolutions. Same as other MST radars worldwide, Beijing MST radar may observe the 3D wind, backscattering power, and signal noise ratio, for different altitude ranges. Based on preliminary observation in certain time periods, results have been shown that both wind profiling from 3-25 km and 60-90 km are observed. Preliminary results show that the present radar can observe the altitude of lower thermosphere, at least in 90-100 km, even to 110 km. Further results will be given.

Lu, Daren; Chen, Zeyu; Wang, Yong; Zhang, Wenxing; Duan, Shu

2012-07-01

322

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

323

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

324

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

325

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

326

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

NASA Technical Reports Server (NTRS)

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

Statman, Joseph; Jamnejad, Vahraz; Nguyen, Lee

2012-01-01

327

Multinozzle Emitter Arrays for Nanoelectrospray Mass Spectrometry  

SciTech Connect

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.

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

2011-06-16

328

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

329

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,

330

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

NASA Astrophysics Data System (ADS)

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

Chen, Rachel; Liu, Baokun

2014-06-01

331

Radar shadow detection in synthetic aperture radar images using digital elevation model and projections  

NASA Astrophysics Data System (ADS)

Synthetic aperture radar (SAR) images are currently widely used in target recognition tasks. In this work, we propose an automatic approach for radar shadow detection and extraction from SAR images utilizing geometric projections along with the digital elevation model (DEM), which corresponds to the given georeferenced SAR image. First, the DEM is rotated into the radar geometry, so that each row would match that of a radar line of sight. Next, we extract the shadow regions by processing row by row until the image is covered fully. We test the proposed shadow detection approach on different DEMs and simulated one-dimensional signals and two-dimensional hills and valleys modeled by various variance-based Gaussian functions. Experimental results indicate that the proposed algorithm produces good results in detecting shadows in SAR images with high resolution.

Prasath, V. B. Surya; Haddad, Oussama

2014-01-01

332

Real-time transverse emittance diagnostics  

SciTech Connect

With the increasing interest in high-brightness beams and the recent advances in photoemission guns capable of producing such high-charge, low-emittance beams, measuring transverse emittance has become a primary concern, especially in driver accelerators for free-electron lasers (FELs) where a degradation of this parameter could result in significant deterioration of the FEL gain. Hence, frequent and fast measurement are needed, particularly when detailed parametric studies are required. Commonly used methods include optical transition radiation (OTR) based methods and trace space sampling methods. The authors will discuss these methods and provide motivation for their method of on-line emittance measurement in the Jefferson Lab FEL.

P.Piot; G.A. Krafft; R. Li; J. Song

1998-08-01

333

PROTOTYPE LASER EMITTANCE SCANNER FOR SNS ACCELERATOR  

SciTech Connect

Taking Advantage of recent successes with the Laser Profile monitor, a new prototype is being built to use the laser wire as both a profile monitor and a slit for an emittance measuring device. This improved system takes advantage of the steering dipole magnet prior to ring injection of SNS such that only the recently stripped H0 protons continue forward to the emittance device. In this way we hope to make an emittance device that is both parasitic to neutron production, and capable of accurate measurements during full power applications.

Pogge, James R [ORNL; Jeon, Dong-O [ORNL; Menshov, Alexander A [ORNL; Nesterenko, Igor N [ORNL

2009-01-01

334

Preliminary study of gun emittance correction  

NASA Astrophysics Data System (ADS)

The standard emittance calculation removes linear correlations between transverse displacement r and the divergence r-prime. Higher-order correlations remain, and they are responsible for a substantial area in phase space which corresponds to the calculated emittance. Time dependent correlations are identified, and a procedure is proposed to remove them. The Brookhaven National Laboratory RF gun has been studied; however, in order to demonstrate the desired effects more clearly, the accelerating field and bunch length have been assumed to be more optimistic than the present operating values. This approach reduces the realizable emittance by a factor of 5 with respect to the value before the correction.

Gallardo, Juan C.; Palmer, Robert B.

1990-08-01

335

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

336

On Radar Time and the Twin `Paradox'  

E-print Network

In this paper we apply the concept of radar time (popularised by Bondi in his work on k-calculus) to the well-known relativistic twin `paradox'. Radar time is used to define hypersurfaces of simultaneity for a class of travelling twins, from the `Immediate Turn-around' case, through the `Gradual Turn-around' case, to the `Uniformly Accelerating' case. We show that this definition of simultaneity is independent of choice of coordinates, and assigns a unique time to any event (with which the travelling twin can send and receive signals), resolving some common misconceptions.

Carl E. Dolby; Stephen F. Gull

2001-04-24

337

Turbulent scattering for radars: A summary  

NASA Astrophysics Data System (ADS)

In this paper some classical concepts regarding scattering of radio waves on turbulent structures in the ionosphere are summarized. Spectral representations according to Batchelor and Driscoll & Kennedy are compared and the role of various potential tracer gradients is elucidated. Systematic similarities and differences in the representation of the impact of these tracers on scatter intensity are investigated. The importance of turbulence and background parameters for radar volume reflectivities is discussed. This study highlights the importance of measuring these parameters as completely and reliably as possible when interpreting the strength of backscattered radar signal in terms of turbulent and atmospheric background parameters.

Lbken, Franz-Josef

2014-01-01

338

SAR raw signal simulation for urban structures  

Microsoft Academic Search

A synthetic aperture radar (SAR) raw signal simulator for urban scenes is presented along with models it employs to compute the backscattered field and to account for the imaging radar sensor characteristics. Urban areas are represented as a set of dielectric buildings placed over a random rough nonflat dielectric terrain. The adopted models allow evaluation of the raw signal on

Giorgio Franceschetti; Antonio Iodice; Daniele Riccio; Giuseppe Ruello

2003-01-01

339

Graded electron affinity semiconductor field emitter  

NASA Astrophysics Data System (ADS)

A field emitter is disclosed comprising a graded electron affinity surface layer. The graded electron affinity layer provides for increased transconductance, reduced energy distribution of emitted electrons, reduced noise and increased uniformity in its operation.

Shaw, Jonathan L.; Jesen, Kevin; Gray, Henry F.

1995-07-01

340

Program to research emittance growth in bends.  

National Technical Information Service (NTIS)

A research program to explore the phenomenon of emittance growth in bends due to noninertial space-charge effects has been defined and initiated. The program combines theoretical, numerical, and experimental investigations. This paper summarizes the motiv...

C. L. Bohn

1995-01-01

341

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

342

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

343

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

344

Meson production decreases with increasing proton beam emittance, but  

E-print Network

Meson production decreases with increasing proton beam emittance, but careful optimization keeps and transverse emittance = 5 m- rad, compared to the case of zero emittance beams. The optimized meson production a Ga-jet target is then about 88% of that for a Hg-jet target. INFLUENCE OF PROTON BEAM EMITTANCES

McDonald, Kirk

345

Suppression of power line harmonic interference in HF surface-wave radar  

Microsoft Academic Search

Experimental data of the Cape Bonavista High-Frequency Surface-Wave Radar (HFSWR) Facility was contaminated by power line harmonics. The harmonics modulate the radar signal (mainly sea clutter) and replicate it into the Doppler spectrum. The spectral replicas distort the noise and sea clutter statistics in the signal. It is necessary to suppress them before the statistics can be obtained. A new

Hank Leong

1992-01-01

346

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

347

Charge neutrality in heavily doped emitters  

SciTech Connect

The applicability of the quasineutrality approximation to modern emitters of solar cells is analytically reviewed. It is shown that this approximation is fulfilled in more than 80% of the depth of a typical solar-cell emitter, being particularly excellent in the heavily doped regions beneath the surface where most of the heavy doping effects arise. Our conclusions are in conflict with Redfield's recent affirmations.

del Alamo, J.A.

1981-09-01

348

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

349

Emitter wrap-through solar cell  

Microsoft Academic Search

The authors present a new solar cell concept (emitter wrap-through or EWT) for a back-contact cell. The cell has laser-drilled vias to wrap the emitter on the front surface to contacts on the back surface and uses a potentially low-cost process sequence. Modeling calculations show that efficiencies of 18 and 21% are possible with large-area solar-grade multi- and monocrystalline silicon

James M. Gee; W. Kent Schubert; Paul A. Basore

1993-01-01

350

Noncooperative rendezvous radar system  

NASA Technical Reports Server (NTRS)

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

1974-01-01

351

Micropower impulse radar  

Microsoft Academic Search

Invented and developed at LLNL (Lawrence Livermore National Laboratory), this inexpensive and highly sensitive radar system produces and samples extremely short pulses of energy. This novel technology is finding dozens of new uses in Laboratory programs and in sensor devices for homes, automobiles, factories, and hospitals. We have invented and patented a fundamentally different type of compact, low-power radar system

S. Azevedo; T. E. McEwan

1997-01-01

352

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

353

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

354

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

355

Equatorial MU Radar project  

NASA Astrophysics Data System (ADS)

Research Institute for Sustainable Humanosphere, Kyoto University (RISH) has been studying the atmosphere by using radars. The first big facility was the MU (Middle and Upper atmosphere) radar installed in Shiga, Japan in 1984. This is one of the most powerful and multi-functional radar, and is successful of revealing importance of atmospheric waves for the dynamical vertical coupling processes. The next big radar was the Equatorial Atmosphere Radar (EAR) installed at Kototabang, West Sumatra, Indonesia in 2001. The EAR was operated under close collaboration with LAPAN (Indonesia National Institute for Aeronautics and Space), and conducted the long-term continuous observations of the equatorial atmosphere/ionosphere for more than 10 years. The MU radar and the EAR are both utilized for inter-university and international collaborative research program for long time. National Institute for Polar Research (NIPR) joined EISCAT Scientific Association together with Nagoya University, and developed the PANSY radar at Syowa base in Antarctica as a joint project with University of Tokyo. These are the efforts of radar study of the atmosphere/ionosphere in the polar region. Now we can find that Japan holds a global network of big atmospheric/ionospheric radars. The EAR has the limitation of lower sensitivity compared with the other big radars shown above. RISH now proposes a plan of Equatorial MU Radar (EMU) that is to establish the MU-radar class radar next to the EAR. The EMU will have an active phased array antenna with the 163m diameter and 1055 cross-element Yagis. Total output power of the EMU will be more than 500kW. The EMU can detect turbulent echoes from the mesosphere (60-80km). In the ionosphere incoherent-scatter observations of plasma density, drift, and temperature would be possible. Multi-channel receivers will realize radar-imaging observations. The EMU is one of the key facilities in the project "Study of coupling processes in the solar-terrestrial system" for Master Plan 2014 of the Science Council of Japan (SCJ). We show the EMU project and its science in the presentation.

Yamamoto, Mamoru; Hashiguchi, H.; Tsuda, Toshitaka; Yamamoto, Masayuki

356

Laser radar improvements  

NASA Astrophysics Data System (ADS)

A short history of the uses of various laser radars is presented, and appropriate applications of laser and microwave radars are discussed. CO2 laser radar, operating at 10.6 microns, is considered for use in aircraft navigation systems, fire-control systems for armored vehicle and aircraft, missile guidance, severe storm research, line-of-sight command of missiles, wind turbine site surveys, clear-air turbulence monitors for aircraft, and satellite tracking. Microwave radar is all-weather, but is subject to multipath inaccuracies, countermeasures, and angular resolution limitations, so hybrid laser microwave systems look promising for microwave target acquisition and laser tracking. Advantages and disadvantages of the use of ruby, YAG, and CO2 lasers in varying atmospheric conditions are discussed. Development of a laser radar pod for obstacle detection, Doppler navigation, automatic terrain following, hover control, weapon delivery, and precision searching is noted.

Jelalian, A. V.

1981-11-01

357

Generic evaluation tracker database for OTH radar  

NASA Astrophysics Data System (ADS)

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

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

1999-10-01

358

An experimental adaptive radar array system  

NASA Astrophysics Data System (ADS)

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

Gong, Y. H.

359

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

360

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

361

Phased-array radar for airborne systems  

NASA Astrophysics Data System (ADS)

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

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

2003-09-01

362

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

363

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

364

Limits on the detection of low-Doppler targets by a High Frequency hybrid sky-surface wave radar system  

Microsoft Academic Search

A high frequency (HF) radar system comprising a skywave transmit channel and surface wave receive channel is studied. Simple analytic expressions for the resolution of this radar system are determined by considering the spreading of radar signals in Doppler and angle during the ionospheric propagation. The detection of ocean surface targets within the patch of ocean surface illuminated by the

Ryan J. Riddolls

2008-01-01

365

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

Microsoft Academic Search

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

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

2005-01-01

366

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

367

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

368

Radar signals dismount tracking for urban operations  

Microsoft Academic Search

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

Erik Blasch; Uttam Majumder; Michael Minardi

2006-01-01

369

L-band radar sensing of soil moisture  

NASA Technical Reports Server (NTRS)

The objectives of the experiment were to assess the performance of an L-band, 25-cm wavelength imaging synthetic aperture radar (SAR) for soil moisture determination, and to study the temporal variability of radar returns from a number of agricultural fields. A series of overflights was accomplished during March 1977 over an agricultural test site in Kern County, Calif. Soil moisture samples were collected from bare fields at nine sites at depths of 0-2, 2-5, 5-15, and 15-30 cm. These gravimetric measurements were converted to percent of field capacity for correlation to the radar return signal. The initial signal film was optically correlated and scanned to produce image data numbers. These numbers were then converted to relative return power by linear interpolation of the noise power wedge which was introduced in 5-dB steps into the original signal film before and after each data run. Results of correlations between the relative return power and percent of field capacity demonstrate that the relative return power from this imaging radar system is responsive to the amount of soil moisture in bare fields. The signal returned from dry and wet fields where furrowing is parallel to the radar beam differs by about 15 dB. Before this technique can be operationally employed, adequate calibration of the radar system is required to insure comparability of data both from area to area within a single flight and between different flights.

Chang, A. T. C.; Salomonson, V. V.; Atwater, S. G.; Estes, J. E.; Simonett, D. S.; Bryan, M. L.

1980-01-01

370

A helium ionization detector with a thermionic electron emitter for gas chromatography  

Microsoft Academic Search

The principal circuit of a helium ionization detector with a thermionic electron emitter (He-IDTEE) is described. The detector\\u000a works at atmospheric pressure. The characteristics of the detector were studied. The difference between the voltammetric characteristics\\u000a of He-IDTEE and that of a helium ionization detector with a radioactive source was shown. The dependences of the analytical\\u000a signal, background signal, and noise

Yu. A. Saprykin; V. M. Tsmots; M. V. Tsyuper; Yu. A. Pazderskii

2009-01-01

371

Spaceborne meteorological radar studies  

NASA Technical Reports Server (NTRS)

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

Meneghini, R.

1988-01-01

372

Space object observation with radar  

NASA Astrophysics Data System (ADS)

FGAN developed a High Power Radar System, able to track and image low Earth orbiting objects, for experimental radar research. The system is unique in Germany; it consists of a narrow band tracking radar and a high resolution imaging radar. The radars are supported from one 34-m parabolic dish antenna. They operate simultaneously on the object of interest. All information which a radar can gain about physical characteristics of targets have to be extracted from the backscattered electromagnetic field of transmitted pulses. L-band tracking data provide information on range, range rate, angular direction, and radar cross-section. From high resolution polarimetric Ku-band radar data projections of the 1- and 2-dimensional scatter centre distributions are computed. This paper gives a brief description of the FGAN radar and summarizes some radar based methods for orbit analysis, orbital lifetime prediction, reconstruction of object images, assessment of object dimensions, shape, attitude, and mass.

Mehrholz, D.

1993-08-01

373

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

374

Holographic surveillance radar  

NASA Astrophysics Data System (ADS)

Since the 1940s, radar development has focused on narrow-beam, scanning sensors. A wide field of view has advantages in terms of extended acquisition time for any target, and when combined with a high Doppler sampling frequency can yield high-resolution Doppler spectra. Unambiguous range and Doppler can be achieved under certain circumstances, resulting in enhanced ability to evaluate the characteristics of targets and clutter. Holographic radar has a range of applications in which the ability to discriminate targets among clutter is key. An example of such an application is in mitigation of wind farm interference with Air Traffic Control radar.

Oswald, Gordon K. A.

2009-05-01

375

Micropower impulse radar  

SciTech Connect

Invented and developed at Lawrence Livermore National Laboratory is an inexpensive and highly sensitive, low-power radar system that produces and samples extremely short pulses of energy at the rate of 2 million per second. Called micropower impulse radar (MIR), it can detect objects at a greater variety of distances with greater sensitivity than conventional radar. Its origins in the Laboratory`s Laser Directorate stem from Nova`s transient digitizer. The MIR`s extraordinary range of applications include security, search and rescue, life support, nondestructive evaluation, and transportation.

Azevedo, S.; McEwan, T.E.

1996-01-01

376

Slope stability radar for monitoring mine walls  

NASA Astrophysics Data System (ADS)

Determining slope stability in a mining operation is an important task. This is especially true when the mine workings are close to a potentially unstable slope. A common technique to determine slope stability is to monitor the small precursory movements, which occur prior to collapse. The slope stability radar has been developed to remotely scan a rock slope to continuously monitor the spatial deformation of the face. Using differential radar interferometry, the system can detect deformation movements of a rough wall with sub-millimeter accuracy, and with high spatial and temporal resolution. The effects of atmospheric variations and spurious signals can be reduced via signal processing means. The advantage of radar over other monitoring techniques is that it provides full area coverage without the need for mounted reflectors or equipment on the wall. In addition, the radar waves adequately penetrate through rain, dust and smoke to give reliable measurements, twenty-four hours a day. The system has been trialed at three open-cut coal mines in Australia, which demonstrated the potential for real-time monitoring of slope stability during active mining operations.

Reeves, Bryan; Noon, David A.; Stickley, Glen F.; Longstaff, Dennis

2001-11-01

377

Physically based simulator for measurements of precipitation with polarimetric and space-borne radars  

NASA Astrophysics Data System (ADS)

A radar is a powerful tool for measurement of the 3-D structure of precipitation. Recently, polarimetric radar is widely used because it can measure the size of raindrops to some degree and therefore can measures more accurate rainfall rate than the conventional weather radar. A space-borne radar is also widely used in precipitation studies. The Tropical Rainfall Measuring Mission (TRMM) satellite has been continuously monitoring precipitation on a global scale since the launch in November, 1977. Following the TRMM, the Global Precipitation Mission (GPM) is scheduled to launch in 2013. The polarimetric parameters observed with the polarimetric radar depend on various precipitation properties in a complex way. Multiple scattering contributions cannot be neglected for a radar operated at higher frequency of 35 GHz higher onboard the GPM. To develop a robust algorithm for more accurate measurements of precipitation from those radars, we should evaluate how micro-physical properties of precipitation link to the received signals. We have developed a generalized radar simulator for polarimetric and space-borne radar (GPASS). This is a physically-based simulator in which the scattering properties of cloud and raindrops are calculated by using radio wave scattering theory. Thus we can make detailed study how the radar signals vary with micro-physical properties of precipitation by using the simulator. We will present the simulator in detail and the limit of the Rayleigh approximation for polarimetric radar.

Kobayashi, Takahisa; Masuda, Kazuhiko; Yamauchi, Hiroshi; Adachi, Ahoro

2011-11-01

378

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

379

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

Microsoft Academic Search

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

He Jianguo; Lu Zhongliang; Su Yi

1995-01-01

380

Radar observations of individual rain drops in the free atmosphere  

PubMed Central

Atmospheric remote sensing has played a pivotal role in the increasingly sophisticated representation of clouds in the numerical models used to assess global and regional climate change. This has been accomplished because the underlying bulk cloud properties can be derived from a statistical analysis of the returned microwave signals scattered by a diverse ensemble comprised of numerous cloud hydrometeors. A new Doppler radar, previously used to track small debris particles shed from the NASA space shuttle during launch, is shown to also have the capacity to detect individual cloud hydrometeors in the free atmosphere. Similar to the traces left behind on film by subatomic particles, larger cloud particles were observed to leave a well-defined radar signature (or streak), which could be analyzed to infer the underlying particle properties. We examine the unique radar and environmental conditions leading to the formation of the radar streaks and develop a theoretical framework which reveals the regulating role of the background radar reflectivity on their observed characteristics. This main expectation from theory is examined through an analysis of the drop properties inferred from radar and in situ aircraft measurements obtained in two contrasting regions of an observed multicellular storm system. The observations are placed in context of the parent storm circulation through the use of the radars unique high-resolution waveforms, which allow the bulk and individual hydrometeor properties to be inferred at the same time. PMID:22652569

Schmidt, Jerome M.; Flatau, Piotr J.; Harasti, Paul R.; Yates, Robert D.; Littleton, Ricky; Pritchard, Michael S.; Fischer, Jody M.; Fischer, Erin J.; Kohri, William J.; Vetter, Jerome R.; Richman, Scott; Baranowski, Dariusz B.; Anderson, Mark J.; Fletcher, Ed; Lando, David W.

2012-01-01

381

Enhanced angular current intensity from Schottky emitters.  

PubMed

Even though the Schottky emitter is a high-brightness source of choice for electron beam systems, its angular current intensity is substantially lower than that of thermionic cathodes, rendering the emitter impractical for applications that require high beam current. In this study, two strategies were attempted to enhance its angular intensity, and their experimental results are reported. The first scheme is to employ a higher extraction field for increasing the brightness. However, the tip shape transformation was found to induce undesirably elevated emission from the facet edges at high fields. The second scheme exploits the fact that the angular intensity is proportional to the square of the electron gun focal length [Fujita, S. & Shimoyama, H. (2005) Theory of cathode trajectory characterization by canonical mapping transformation. J. Electron Microsc. 54, 331-343], which can be increased by scaling-up the emitter tip radius. A high angular current intensity (J(Omega) approximately 1.5 mA sr(-1)) was obtained from a scaled-up emitter. Preliminary performance tests were conducted on an electron probe-forming column by substituting the new emitter for the original tungsten filament gun. The beam current up to a few microamperes was achieved with submicron spatial resolution. PMID:20701659

Fujita, S; Wells, T R C; Ushio, W; Sato, H; El-Gomati, M M

2010-09-01

382

Correlations in optically-controlled quantum emitters  

E-print Network

We address the problem of optically controlling and quantifying the dissipative dynamics of quantum and classical correlations in a set-up of individual quantum emitters under external laser excitation. We show that both types of correlations, the former measured by the quantum discord, are present in the system's evolution even though the emitters may exhibit an early stage disentanglement. In the absence of external laser pumping,we demonstrate analytically, for a set of suitable initial states, that there is an entropy bound for which quantum discord and entanglement of the emitters are always greater than classical correlations, thus disproving an early conjecture that classical correlations are greater than quantum correlations. Furthermore, we show that quantum correlations can also be greater than classical correlations when the system is driven by a laser field. For scenarios where the emitters' quantum correlations are below their classical counterparts, an optimization of the evolution of the quantum correlations can be carried out by appropriately tailoring the amplitude of the laser field and the emitters' dipole-dipole interaction. We stress the importance of using the entanglement of formation, rather than the concurrence, as the entanglement measure, since the latter can grow beyond the total correlations and thus give incorrect results on the actual system's degree of entanglement.

Cristian E. Susa; John H. Reina

2011-12-19

383

Ionospheric Transmission Losses Associated with Mars-orbiting Radars  

NASA Technical Reports Server (NTRS)

There are a number of obstacles to radar sounding of the deep Martian subsurface from orbit, including signal losses from the medium conductivity, layer reflective losses, and ground clutter. Another adverse process is signal loss as radio waves propagate through the ionospheric plasma medium. The ionosphere is a plasma consisting of free electrons, ions and neutrals that can effectively damp/attenuate radar signals via electrodneutral collisions. The effect is most severe for transmissions at lower frequencies, which, unfortunately, are also favorable transmissions for deep penetration into the subsurface.

Farrell, W. M.

2005-01-01

384

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.

385

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, Raul; Carrasco-Alvarez, Ruben; Rosa-Zurera, Manuel; Nieto-Borge, Jose Carlos

2009-01-01

386

Instantaneous electron beam emittance measurement system based on the optical transition radiation principle  

NASA Astrophysics Data System (ADS)

One kind of instantaneous electron beam emittance measurement system based on the optical transition radiation principle and double imaging optical method has been set up. It is mainly adopted in the test for the intense electron-beam produced by a linear induction accelerator. The system features two characteristics. The first one concerns the system synchronization signal triggered by the following edge of the main output waveform from a Blumlein switch. The synchronous precision of about 1 ns between the electron beam and the image capture time can be reached in this way so that the electron beam emittance at the desired time point can be obtained. The other advantage of the system is the ability to obtain the beam spot and beam divergence in one measurement so that the calculated result is the true beam emittance at that time, which can explain the electron beam condition. It provides to be a powerful beam diagnostic method for a 2.5 kA, 18.5 MeV, 90 ns (FWHM) electron beam pulse produced by Dragon I. The ability of the instantaneous measurement is about 3 ns and it can measure the beam emittance at any time point during one beam pulse. A series of beam emittances have been obtained for Dragon I. The typical beam spot is 9.0 mm (FWHM) in diameter and the corresponding beam divergence is about 10.5 mrad.

Jiang, Xiao-Guo; Wang, Yuan; Zhang, Kai-Zhi; Yang, Guo-Jun; Shi, Jin-Shui; Deng, Jian-Jun; Li, Jin

2014-01-01

387

Suppressing coherent noise in radar applications with long dwell times  

E-print Network

Science Foundation under Grant OPP-0122520 and in part by the National Aeronautics and Space Administration under Grant NGT5-30449. The authors are with the Department of Electrical Engineering and Com- puter Science, University of Kansas, Lawrence, KS.... In such systems, the use of long dwell times allows the radar to operate with a reduced transmit power level without degrading the radar sensitivity by averaging the echo signals to reduce the random noise level. Due to its nonrandom nature, coherent noise...

Allen, Christopher Thomas; Mozaffar, S. N.; Akins, T. L.

2005-07-01

388

Three-dimensional imaging coherent laser radar array  

Microsoft Academic Search

A small-scale laboratory demonstration of a laser-diode-based radar array has been constructed for simultaneous coherent ranging and velocimetry of multiple target points. Signals are produced by an array of laser\\/detector packages in a self-detection geometry with common imaging optics for both the source and backscattered light. The radar has been used with a microcomputer to find the orientation and rotation

Peter J. de Groot; Gregg M. Gallatin

1989-01-01

389

A review of multiparameter radar observations of precipitation  

Microsoft Academic Search

From the earliest years of radar meteorology, efforts have been devoted to multiparameter observations: the measurement of one or more signal properties, ordinarily in addition to the signal intensity, to give added information about the precipitation. Studies employing variable polarization or Doppler frequency measurement were among the first such techniques and over the years have proved fruitful in terms of

R. R. Rogers

1984-01-01

390

Phase and amplitude phase restoration in synthetic aperture radar imaging.  

PubMed

Methods for addressing two types of multiplicative noise in synthetic aperture radar (SAR) imaging are presented. The authors consider a multiplicative noise with a real phase (i.e. the SAR signal's phase is contaminated but its amplitude is uncorrupted) that possesses unknown functional characteristics with respect to the radar signal's temporal frequencies. A perturbation solution for phase reconstruction from amplitude is developed from a wave equation governing the SAR signal and a Riccati equation that relates the amplitude and phase functions of the SAR signal. This solution is converted into a noniterative analytical solution in terms of the moments and powers of the log amplitude function. Next, the authors consider a multiplicative noise with a complex phase (i.e. both the amplitude and phase of the SAR signal are contaminated) that varies linearly with respect to the radar signal's temporal frequencies. The two wave equations governing the SAR signal at two temporal frequencies of the radar signal are combined to derive a method to reconstruct the complex phase error function. PMID:18296157

Soumekh, M; Choi, J H

1992-01-01

391

Studies of target signatures with a coherent laser radar  

Microsoft Academic Search

Measurements of target signatures performed with a CO2 laboratory laser radar of a homodyne doppler type are described. Receiver sensitivity and dependence on aperture and target signatures are discussed, as well as imaging and ranging out to 2 km. The measurements of target signatures refer to signal amplitude spectra, noise and root mean square signals. The detection probabilities at various

G. Bolander; K. Gullberg; I. Renhorn; O. Steinvall; A. Widen

1981-01-01

392

Considerations in measuring vital signs cross section with Doppler radar  

Microsoft Academic Search

This paper describes the different considerations and challenges in measuring human cardiopulmonary radar cross section (RCS). The effect of clutter on the received signal is explained as well as the importance of preserving baseband dc content for valid readings. The center estimation algorithm with dc- cancellation is presented as a solution to restore dc content in the baseband signals and

John E. Kiriazi; Olga Boric-Lubecke; Victor M. Lubecke

2011-01-01

393

A Method to Measure Radar Cross Section Parameters of Antennas  

Microsoft Academic Search

A new method to measure radar cross section (RCS) parameters of antennas is presented in this paper. This method relies on an equation derived for the received signal power which is represented as the superposition of structural-mode scattered, antenna-mode scattered, and leakage signals. The method also measures relative phase and provides the effect of the load connected to the antenna.

Sudhir Shrestha; M. D. Balachandran; Mangilal Agarwal; Li-He Zou; Kody Varahramyan

2008-01-01

394

Caribbean Radar Products  

NSDL National Science Digital Library

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

Comet

2013-12-31

395

Radar Calibration Test Satellite  

Microsoft Academic Search

A satellite has been designed for application to radar calibration. Electromagnetic and mechanical characteristics of the satellite and their influence on the selection of shape and other parameters are discussed. Theoretical and experimental scattering data are included.

L. J. Kaplan; J. F. A. Ormsby; EVERT N. FOWLE; KENT R. JOHNSON; Richard T. Bates; S. H. Bickel

1969-01-01

396

A smart radar absorber  

Microsoft Academic Search

This paper proposes a configuration for a smart radar absorber which is capable of both self-tuning and absorb while scan operation. The discussion is complemented by modelled and measured performance data.

Barry Chambers

1999-01-01

397

Laser Radar Animation  

NASA Video Gallery

Laser and radar instruments aboard NASA aircraft provide measurements of the snow and ice surface and down to the bedrock under the ice. Lasers, with a shorter wavelength, measure the surface eleva...

398

Phased-array radars  

NASA Astrophysics Data System (ADS)

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

Brookner, E.

1985-02-01

399

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

400

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

401

Head erosion with emittance growth in PWFA  

SciTech Connect

Head erosion is one of the limiting factors in plasma wakefield acceleration (PWFA). We present a study of head erosion with emittance growth in field-ionized plasma from the PWFA experiments performed at the FACET user facility at SLAC. At FACET, a 20.3 GeV bunch with 1.8 Multiplication-Sign 10{sup 10} electrons is optimized in beam transverse size and combined with a high density lithium plasma for beam-driven plasma wakefield acceleration experiments. A target foil is inserted upstream of the plasma source to increase the bunch emittance through multiple scattering. Its effect on beamplasma interaction is observed with an energy spectrometer after a vertical bend magnet. Results from the first experiments show that increasing the emittance has suppressed vapor field-ionization and plasma wakefields excitation. Plans for the future are presented.

Li, S. Z.; Adli, E.; England, R. J.; Frederico, J.; Gessner, S. J.; Hogan, M. J.; Litos, M. D.; Walz, D. R.; Muggli, P.; An, W.; Clayton, C. E.; Joshi, C.; Lu, W.; Marsh, K. A.; Mori, W.; Vafaei, N. [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States) and SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States) and University of Oslo, Oslo, N-0316 (Norway) and SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Max Planck Institute for Physics, Munich (Germany); University of California, Los Angeles, CA 90095 (United States)

2012-12-21

402

BEAM EMITTANCE MEASUREMENT TOOL FOR CEBAF OPERATIONS  

SciTech Connect

A new software tool was created at Jefferson Lab to measure the emittance of the CEBAF electron beams. The tool consists of device control and data analysis applications. The device control application handles the work of wire scanners and writes their measurement results as well as the information about accelerator settings during these measurements into wire scanner data files. The data analysis application reads these files and calculates the beam emittance on the basis of a wire scanner data processing model. Both applications are computer platform independent but are mostly used on LINUX PCs recently installed in the accelerator control room. The new tool significantly simplifies beam emittance measurement procedures for accelerator operations and contributes to a very high availability of the CEBAF machine for the nuclear physics program at Jefferson Lab.

Chevtsov, Pavel; Tiefenback, Michael

2008-10-01

403

Quantitative deconvolution of human thermal infrared emittance.  

PubMed

The bioheat transfer models conventionally employed in etiology of human thermal infrared (TIR) emittance rely upon two assumptions; universal graybody emissivity and significant transmission of heat from subsurface tissue layers. In this work, a series of clinical and laboratory experiments were designed and carried out to conclusively evaluate the validity of the two assumptions. Results obtained from the objective analyses of TIR images of human facial and tibial regions demonstrated significant variations in spectral thermophysical properties at different anatomic locations on human body. The limited validity of the two assumptions signifies need for quantitative deconvolution of human TIR emittance in clinical, psychophysiological and critical applications. A novel approach to joint inversion of the bioheat transfer model is also introduced, levering the deterministic temperature-dependency of proton resonance frequency in low-lipid human soft tissue for characterizing the relationship between subsurface 3D tissue temperature profiles and corresponding TIR emittance. PMID:23086533

Arthur, D T J; Khan, M M

2013-01-01

404

On wave radar measurement  

NASA Astrophysics Data System (ADS)

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

Ewans, Kevin; Feld, Graham; Jonathan, Philip

2014-09-01

405

Optimized aperiodic highly directional narrowband infrared emitters  

NASA Astrophysics Data System (ADS)

Bulk thermal emittance sources possess incoherent, isotropic, and broadband radiation spectra that vary from material to material. However, these radiation spectra can be drastically altered by modifying the geometry of the structures. In particular, several approaches have been proposed to achieve narrowband, highly directional thermal emittance based on photonic crystals, gratings, textured metal surfaces, metamaterials, and shock waves propagating through a crystal. Here we present optimized aperiodic structures for use as narrowband, highly directional thermal infrared emitters for both TE and TM polarizations. One-dimensional layered structures without texturing are preferable to more complex two- and three-dimensional structures because of the relative ease and low cost of fabrication. These aperiodic multilayer structures designed with alternating layers of silicon and silica on top of a semi-infinite tungsten substrate exhibit extremely high emittance peaked around the wavelength at which the structures are optimized. Structures were designed by a genetic optimization algorithm coupled to a transfer matrix code which computed thermal emittance. First, we investigate the properties of the genetic-algorithm optimized aperiodic structures and compare them to a previously proposed resonant cavity design. Second, we investigate a structure optimized to operate at the Wien wavelength corresponding to a near-maximum operating temperature for the materials used in the aperiodic structure. Finally, we present a structure that exhibits nearly monochromatic and highly directional emittance for both TE and TM polarizations at the frequency of one of the molecular resonances of carbon monoxide (CO); hence, the design is suitable for a detector of CO via absorption spectroscopy.

Granier, Christopher H.; Afzal, Francis O.; Min, Changjun; Dowling, Jonathan P.; Veronis, Georgios

2014-09-01

406

SNS Emittance Scanner, Increasing Sensitivity and Performance through Noise Mitigation ,Design, Implementation and Results  

SciTech Connect

The Spallation Neutron Source (SNS) accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The SNS MEBT Emittance Harp consists of 16 X and 16 Y wires, located in close proximity to the RFQ, Source, and MEBT Choppers. Beam Studies for source and LINAC commissioning required an overall increase in sensitivity for halo monitoring and measurement, and at the same time several severe noise sources had to be effectively removed from the harp signals. This paper is an overview of the design approach and techniques used in increasing gain and sensitivity while maintaining a large signal to noise ratio for the emittance scanner device. A brief discussion of the identification of the noise sources, the mechanism for transmission and pick up, how the signals were improved and a summary of results.

Pogge, J. [ORNL, Bethel Valley Rd, Oak Ridge (United States)

2006-11-20

407

Heterojunction solar cell with passivated emitter surface  

DOEpatents

A high-efficiency heterojunction solar cell wherein a thin emitter layer (preferably Ga.sub.0.52 In.sub.0.48 P) forms a heterojunction with a GaAs absorber layer. A passivating window layer of defined composition is disposed over the emitter layer. The conversion efficiency of the solar cell is at least 25.7%. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the window layer.

Olson, Jerry M. (Lakewood, CO); Kurtz, Sarah R. (Golden, CO)

1994-01-01

408

Heterojunction solar cell with passivated emitter surface  

DOEpatents

A high-efficiency heterojunction solar cell is described wherein a thin emitter layer (preferably Ga[sub 0.52]In[sub 0.48]P) forms a heterojunction with a GaAs absorber layer. A passivating window layer of defined composition is disposed over the emitter layer. The conversion efficiency of the solar cell is at least 25.7%. The solar cell preferably includes a passivating layer between the substrate and the absorber layer. An anti-reflection coating is preferably disposed over the window layer. 1 fig.

Olson, J.M.; Kurtz, S.R.

1994-05-31

409

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

410

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

411

Tactical and atmospheric coherent laser radar technology  

Microsoft Academic Search

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

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

1983-01-01

412

AirRadar 1.1.1  

NSDL National Science Digital Library

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

413

Synchronous Photodiode-Signal Sampler  

NASA Technical Reports Server (NTRS)

Synchronous sampling circuit increases signal-to-noise ratio of measurements of chopped signal of known phase and frequency in presence of low-frequency or dc background noise. Used with linear array of photoelectric sensors for locating edge of metal plate. Multiplexing circuit cycles through 16 light-emitting-diode/photodiode pairs, under computer control. Synchronized with multiplexer so edge detector makes one background-subtracted signal measurement per emitter/detector pair in turn.

Primus, Howard K.

1988-01-01

414

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

Microsoft Academic Search

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

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

2006-01-01

415

Measurement of Correlation Functions and Power Spectra in Clouds Using the NRL WARLOC Radar  

Microsoft Academic Search

The Naval Research Laboratory W-band Advanced Radar for Low Observable Control (WARLOC) is a high-power 94-GHz radar, with 3-10-kW average and 80-kW peak power, now set up on the western shore of the Chesapeake Bay. It has three orders of magnitude more power and sensitivity than other W-band radar systems. This enables cloud reflectivity to be measured with high signal-to-noise

Arne W. Fliflet; Wallace M. Manheimer

2006-01-01

416

Emittance growth from electron beam modulation  

SciTech Connect

In linac ring colliders like MeRHIC and eRHIC a modulation of the electron bunch can lead to a modulation of the beam beam tune shift and steering errors. These modulations can lead to emittance growth. This note presents simple formulas to estimate these effects which generalize some previous results.

Blaskiewicz, M.

2009-12-01

417

Aluminum oxide film thickness and emittance  

SciTech Connect

Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55{degrees}C) moderator for about a year. The average moderator temperature was assumed to be 30{degrees}C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 {mu}m {plus minus} 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 {mu}m {plus minus} 11%. Total hemispherical emittance is predicted to be 0.69 at 96{degrees}C, decreasing to 0.45 at 600{degrees}C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values.

Thomas, J.K.; Ondrejcin, R.S.

1991-11-01

418

Aluminum oxide film thickness and emittance  

SciTech Connect

Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55{degrees}C) moderator for about a year. The average moderator temperature was assumed to be 30{degrees}C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 {mu}m {plus_minus} 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 {mu}m {plus_minus} 11%. Total hemispherical emittance is predicted to be 0.69 at 96{degrees}C, decreasing to 0.45 at 600{degrees}C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values.

Thomas, J.K.; Ondrejcin, R.S.

1991-11-01

419

Emittance control in rf cavities and solenoids  

NASA Astrophysics Data System (ADS)

We study emittance growth for transport of uniform and Gaussian beams of particles in rf cavities and solenoids and show analytically its dependence on initial beam parameters. Analytical results are confirmed with simulation studies over a broad range of different initial beams.

Eshraqi, Mohammad; Franchetti, Giuliano; Lombardi, Alessandra M.

2009-02-01

420

Emittance in particle and radiation beam techniques  

SciTech Connect

The author discusses the important and diverse role of the phase space area - the emittance - in the advanced techniques involving interaction of particle and radiation beams. For undulator radiation from unbunched beams, the radiation phase space is diluted from the coherent phase space of the single electron radiation. When the undulator radiation is used as a light source, it is important to minimize the dilution by decreasing the beam emittance and matching the phase space distributions of the particle and the radiation beams. For optical stochastic cooling, on the other hand, the phase space should be maximally mismatched for efficient cooling. In the case particles are bunched to a length much shorter than the radiation wavelength, the emittance appears as an intensity enhancement factor. In the operation of free electron lasers, the phase space matching becomes doubly important, once as the dilution factor in the initial stage of energy modulation and then as the radiation efficiency factor at the end where the beam is density modulated. The author then discusses some of the beam cooling techniques producing smaller emittances, especially the recent suggestions for relativistic heavy ions in storage rings or electron beams in linacs. These are based on the radiative cooling that occurs when particle beams backscatter powerful laser beams.

Kim, Kwang-Je

1997-03-01

421

Single platform passive Doppler geolocation with unknown emitter frequency  

Microsoft Academic Search

This paper describes a novel particle filter technique to geolocate radio frequency emitters with unknown emitter frequency using passive, Doppler-shifted frequency measurements. Doppler-based geolocation algorithms suffer in general, from the non-linear and coupled relationship between the unknown emitter location, unknown emitter frequency, and observed Doppler-shifted frequency measurements. This non-linearity precludes a computationally efficient, closed-form implementation and directs algorithmic solutions toward

Hanna Witzgall; Brad Pinney; Michael Tinston

2010-01-01

422

Micro-machined infrared emitter with metallic photonic crystals structure  

NASA Astrophysics Data System (ADS)

Infrared emitter (IR) with photonic crystal structure formed by a hexagonal array of holes has been designed. The processes for fabricating the emitter are developed basing on using silicon-on-insulator (SOI) wafer. The emission spectrum of the IR emitter is measured with spectroradiometer. The experimental results show that the infrared emitter exhibits a strong narrow-band emission in middle infrared range. The wavelengths of the measured emission peaks agree well with the theoretical prediction.

Li, Fangqiang; San, Haisheng; Cheng, Meijing; Chen, Xuyuan

2009-05-01

423

Space Radar Image of Raco Biomass Map  

NASA Technical Reports Server (NTRS)

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

1999-01-01

424

Radar Image, Color as Height , Salalah, Oman  

NASA Technical Reports Server (NTRS)

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

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

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

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

2000-01-01

425

A fully photonics-based coherent radar system  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

426

High brightness fiber laser pump sources based on single emitters and multiple single emitters  

NASA Astrophysics Data System (ADS)

Driven by the potential of the fiber laser market, the development of high brightness pump sources has been pushed during the last years. The main approaches to reach the targets of this market had been the direct coupling of single emitters (SE) on the one hand and the beam shaping of bars and stacks on the other hand, which often causes higher cost per watt. Meanwhile the power of single emitters with 100?m emitter size for direct coupling increased dramatically, which also pushed a new generation of wide stripe emitters or multi emitters (ME) of up to 1000?m emitter size respectively "minibars" with apertures of 3 to 5mm. The advantage of this emitter type compared to traditional bars is it's scalability to power levels of 40W to 60W combined with a small aperture which gives advantages when coupling into a fiber. We show concepts using this multiple single emitters for fiber coupled systems of 25W up to 40W out of a 100?m fiber NA 0.22 with a reasonable optical efficiency. Taking into account a further efficiency optimization and an increase in power of these devices in the near future, the EUR/W ratio pushed by the fiber laser manufacturer will further decrease. Results will be shown as well for higher power pump sources. Additional state of the art tapered fiber bundles for photonic crystal fibers are used to combine 7 (19) pump sources to output powers of 100W (370W) out of a 130?m (250?m) fiber NA 0.6 with nominal 20W per port. Improving those TFB's in the near future and utilizing 40W per pump leg, an output power of even 750W out of 250?m fiber NA 0.6 will be possible. Combined Counter- and Co-Propagated pumping of the fiber will then lead to the first 1kW fiber laser oscillator.

Scheller, Torsten; Wagner, Lars; Wolf, Jrgen; Bonati, Guido; Drfel, Falk; Gabler, Thomas

2008-02-01

427

SRTM Radar - Landsat Image Comparison, Patagonia, Argentina  

NASA Technical Reports Server (NTRS)

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

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

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

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

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

2000-01-01

428

SPARSE SIGNAL REPRESENTATION FOR COMPLEX-VALUED IMAGING Sadegh Samadi 1  

E-print Network

signal representation-based method for complex- valued imaging. Many coherent imaging systems, coherent imaging, synthetic aperture radar. 1. INTRODUCTION This paper presents a new image reconstruction coherent imaging systems such as synthetic aperture radar (SAR), holography, magnetic resonance imaging

?etin, Müjdat

429

Mobile emitter geolocation and tracking using TDOA and FDOA measurements  

Microsoft Academic Search

This paper considers recursive tracking of one mobile emitter using a sequence of time difference of arrival (TDOA) and frequency difference of arrival (FDOA) measurement pairs obtained by one pair of sensors. We consider only a single emitter without data association issues (no missed detections or false measurements). Each TDOA measurement defines a region of possible emitter locations around a

Darko Musicki; Regina Kaune; Wolfgang Koch

2010-01-01

430

Calculation of the emitter efficiency of bipolar transistors  

Microsoft Academic Search

The emitter efficiency of a bipolar transistor is calculated taking heavy doping effects such as impurity band formation and band tailing into account. It is shown that in most cases these effects, rather than the minority carrier lifetime in the emitter are limiting the transistor current gain. This allows us to define an effective emitter impurity profile for use in

ROBERT P. MERTENS; HUGO J. DEMAN; ROGER J. VAN OVERSTRAETEN

1973-01-01

431

Emittance Growth during Bunch Compression in the CTF-II  

Microsoft Academic Search

Measurements of the beam emittance during bunch compression in the CLIC Test Facility (CTF-II) are described. The measurements were made with different beam charges and different energy correlations versus the bunch compressor settings which were varied from no compression through the point of full compression and to overcompression. Significant increases in the beam emittance were observed with the maximum emittance

H. Braun; F. Chautard; R. Corsini; T. O. Raubenheimer; P. Tenenbaum

2000-01-01

432

GENERALIZED EMITTANCE INVARIANTS Govindan Rangarajan, Filippo Neri, and Alex Dragt  

E-print Network

GENERALIZED EMITTANCE INVARIANTS Govindan Rangarajan, Filippo Neri, and Alex Dragt Department of Physics and Astronomy, University of Maryland College Park, IUD 20742 ABSTRACT The mean square emittance of mean square emittance can be generalized to pro- duce three invariants. These invariants (which can

Rangarajan, Govindan

433

On Emitter-Location Problem Yu. Golubev (CNRS, France)  

E-print Network

On Emitter-Location Problem Yu. Golubev (CNRS, France) joint work with V. Potapov (IITP, Russia) S.A.P.S. IX, Le Mans, 11-14 March 2013 #12;The emitter-location technique described in this talk results from on 15 March, 1976. Kaufman, J. E. and Hutchinson, W. K. Emitter Location with LES 8 9 Using Differential

Di Girolami, Cristina

434

PASSIVE EMITTER LOCATION USING DIGITAL TERRAIN DATA TINA L CHOW  

E-print Network

PASSIVE EMITTER LOCATION USING DIGITAL TERRAIN DATA BY TINA L CHOW BS, Electrical and Computer emitter using a single moving platform has always been an important task for many applications. A majority of emitter estimation problems are currently performed using bearing (or angle of arrival) measurements

Fowler, Mark

435

STUDY OF ABNORMAL VERTICAL EMITTANCE GROWTH IN ATF EXTRACTION LINE  

E-print Network

STUDY OF ABNORMAL VERTICAL EMITTANCE GROWTH IN ATF EXTRACTION LINE M. Alabau Pons, IFIC (CSIC, CERN, Geneva, Switzerland Abstract Since several years, the vertical beam emittance mea- sured the emittance measured in the DR itself, and there are indications that it grows rapidly with increasing beam

Paris-Sud XI, Université de

436

C-A/AP/#244 Pepper Pot Emittance Meter  

E-print Network

C-A/AP/#244 July 2006 Pepper Pot Emittance Meter A. Pikin, A. Kponou, J. Ritter, V. Zajic Collider-Accelerator Department Brookhaven National Laboratory Upton, NY 11973 #12;Pepper pot emittance meter A. Pikin, A. Kponou, J. Ritter, V. Zajic BNL C-AD Technote 1. Introduction To measure the emittance of the ion beam

437

Indistinguishability and correlations of photons generated by quantum emitters  

E-print Network

Indistinguishability and correlations of photons generated by quantum emitters undergoing spectral generated by parametric down conversion and then extended to independent emitters. Fluctuations caused by coupling between emitters and a bath can erode the interference which causes the dip. Here we show how

Mukamel, Shaul

438

Advanced Radar Research Center The University of Oklahoma seeks an exceptional, dynamic leader to serve as Director of its Advanced Radar Research Center  

E-print Network

in surface, airborne and space-based defense, security and intelligence. Principal capabilities of the ARRC has expanded capabilities in radar and other electromagnetic technologies, with applications technology; digital signal/array processing; automated algorithms; decision support tools; data assimilation

Oklahoma, University of

439

Microwave emissions from police radar  

E-print Network

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

Fink, John Michael

2012-06-07

440

Venus wind-altitude radar  

NASA Technical Reports Server (NTRS)

A design study on adding a radar altimeter to the Pioneer Venus small probe is review. Block and timing diagrams are provided. The inherent and interface ambiguities, resolution, and data handling logic for radar altimeters are described.

Levanon, N.

1974-01-01

441

Phase modulating the Urbana radar  

NASA Technical Reports Server (NTRS)

The design and operation of a switched phase modulation system for the Urbana Radar System are discussed. The system is implemented and demonstrated using a simple procedure. The radar system and circuits are described and analyzed.

Herrington, L. J., Jr.; Bowhill, S. A.

1983-01-01

442

Landmine detection and imaging using Micropower Impulse Radar (MIR)  

SciTech Connect

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

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

1995-08-07

443

Radar observations of individual rain drops in the free atmosphere.  

PubMed

Atmospheric remote sensing has played a pivotal role in the increasingly sophisticated representation of clouds in the numerical models used to assess global and regional climate change. This has been accomplished because the underlying bulk cloud properties can be derived from a statistical analysis of the returned microwave signals scattered by a diverse ensemble comprised of numerous cloud hydrometeors. A new Doppler radar, previously used to track small debris particles shed from the NASA space shuttle during launch, is shown to also have the capacity to detect individual cloud hydrometeors in the free atmosphere. Similar to the traces left behind on film by subatomic particles, larger cloud particles were observed to leave a well-defined radar signature (or streak), which could be analyzed to infer the underlying particle properties. We examine the unique radar and environmental conditions leading to the formation of the radar streaks and develop a theoretical framework which reveals the regulating role of the background radar reflectivity on their observed characteristics. This main expectation from theory is examined through an analysis of the drop properties inferred from radar and in situ aircraft measurements obtained in two contrasting regions of an observed multicellular storm system. The observations are placed in context of the parent storm circulation through the use of the radar's unique high-resolution waveforms, which allow the bulk and individual hydrometeor properties to be inferred at the same time. PMID:22652569

Schmidt, Jerome M; Flatau, Piotr J; Harasti, Paul R; Yates, Robert D; Littleton, Ricky; Pritchard, Michael S; Fischer, Jody M; Fischer, Erin J; Kohri, William J; Vetter, Jerome R; Richman, Scott; Baranowski, Dariusz B; Anderson, Mark J; Fletcher, Ed; Lando, David W

2012-06-12

444

Long range trace detection by radar REMPI  

NASA Astrophysics Data System (ADS)

We demonstrate the feasibility of using microwave scattering from free electrons generated by resonantly enhanced multi-photon ionization (REMPI) for trace species detection. The laser is tuned to ionize only the selected molecular trace species in ambient air. We achieve detection of parts-per-billion of NO in atmospheric pressure nitrogen, in dry air and in laboratory air with 50% humidity. In addition, we performed at-range measurements in order to prove the feasibility of using the Radar REMPI detection technique in a remote configuration. We obtained reliable backscattered microwave signal 1m away while focusing a laser from 10m distance from the target. We have extended the use of the Radar REMPI detection scheme to more complicated molecular systems by pre-dissociating the molecule into smaller fragments which can be detected with high specificity. We demonstrate the detection of SF6 by laser dissociation of the SF6 molecule, and measuring the Radar REMPI signals obtained from the SF2 product. The SF2 is produced by the UV REMPI laser pulse itself, and a scattered microwave signal is detected from the SF2 molecule. Significant enhancement is achieved using a pre-ionizing pulse from a Nd YAG laser shortly before the measurement. The short time between fragmentation and detection allows transient fragments and fragments in vibrational nonequilibrium to be detected. This approach may allow for the identification of complex molecules by remotely detecting even short lived molecular constituents or fragments which are produced either during or just shortly before the Radar REMPI measurement

Dogariu, Arthur; Stein, Celine; Glaser, Alexander; Miles, Richard B.

2011-05-01

445

Special applications of radar systems  

Microsoft Academic Search

Developments at Dornier in radar equipment are discussed. Characteristics of the Tasyll-1 scoring system for air target simulation are examined with emphasis on the Doppler radar principle for missile location. The RADOBS-R (Radar-object shield panorama sensor) system creates a ring-shaped alarm zone around an object for protection and has an operating frequency around 14 GHz. A Synthetic Aperture Radar and

U. Knepper; R. Kremer; H. Lamprecht; R. Schotter

1980-01-01

446

Radar data smoothing filter study  

NASA Technical Reports Server (NTRS)

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

White, J. V.

1984-01-01

447

Characteristics of Sunset radar  

NASA Technical Reports Server (NTRS)

Located in a narrow canyon 15 km west of Boulder, Colorado, the Sunset pulsed Doppler radar was the first radar designed and constructed specifically as a VHF ST radar. The antenna system is a phased array of coaxial-colinear dopoles with computer-controlled phase shifters for each line of dipoles. It operates at a frequency of 40.475 MHz and a wavelength of 7.41M. Peak transmitter power is 100 kW. Aperture efficiency is 0.58 and resistive loss is 0.30 for its 3600 sq m area. The practical steering rate is 1 record/minute/position to any arbitrary antenna beam position. The first clear-air turbulence echoes and wind velocity measurements were obtained in 1974. Significant accomplishments are listed.

Green, J. L.

1983-01-01

448

Radar sector blanker  

NASA Astrophysics Data System (ADS)

A radar sector blanker comprises in analog-to-digital converter and a sector controller unit. The analog-to-digital converter receives the analog synchro voltages describing the positioning of a radar antenna and changes these voltages into binary-coded decimal (BCD) information. The sector controller unit comprises a portable housing, a controller system, and a power supply. The controller system includes an OFF comparator circuit, an ON comparator circuit, an S-R latch, and a solid-state switch. Each comparator circuit comprises three cascaded transistor-transistor logic (TTL) integrated chips. The power supply gives a direct-current voltage to the solid-state switch and the TTL chips. The sector blanker blocks transmission for a predetermined rotational region or sector of a radar system.

Hall, Roger B.

1994-03-01

449

Side looking radar calibration study  

NASA Technical Reports Server (NTRS)

Calibration of an airborne sidelooking radar is accomplished by the use of a model that relates the radar parameters to the physical mapping situation. Topics discussed include: characteristics of the transmitters; the antennas; target absorption and reradiation; the receiver and map making or radar data processing; and the calibration process.

Edwards, W. D.

1975-01-01

450

INFLUENCE OF EMITTER PROFILE CHARACTERISTICS ON THERMAL STABILITY AND PASSIVIATION QUALITY OF A-SI/SINX-PASSIVATED BORON EMITTERS  

E-print Network

INFLUENCE OF EMITTER PROFILE CHARACTERISTICS ON THERMAL STABILITY AND PASSIVIATION QUALITY OF A-SI/SINX-PASSIVATED BORON EMITTERS M.Kessler 1 , S.Gatz 1 , P.Altermatt 2 , N.-P.Harder 1,3 , and Rolf Brendel 1,2 1 We present emitter saturation current densities (J0E) of different types of BBr3 furnace

451

Signal sciences workshop proceedings  

SciTech Connect

This meeting is aimed primarily at signal processing and controls. The technical program for the 1997 Workshop includes a variety of efforts in the Signal Sciences with applications in the Microtechnology Area a new program at LLNL and a future area of application for both Signal/Image Sciences. Special sessions organized by various individuals in Seismic and Optical Signal Processing as well as Micro-Impulse Radar Processing highlight the program, while the speakers at the Signal Processing Applications session discuss various applications of signal processing/control to real world problems. For the more theoretical, a session on Signal Processing Algorithms was organized as well as for the more pragmatic, featuring a session on Real-Time Signal Processing.

Candy, J.V.

1997-05-01

452

HF radar ionospheric clutter  

NASA Astrophysics Data System (ADS)

The characteristics of HF radar echoes reflected from ionization irregularities aligned along the lines of force of the Earth's magnetic field are presented. Utilizing experimental radar-ionospheric clutter data acquired at frequencies between HF and UHF, an analysis is made of the amplitude, the cross-sectional area and the angular extent statistics of HF field-aligned echoes. The Doppler frequency variation, the frequency of occurrence and the diurnal and seasonal variation of HF ionospheric backscatter echoes and their correlation with solar-geophysical conditions are also discussed.

Millman, G. H.

1982-08-01

453

Spaceborne Imaging Radar Symposium  

NASA Technical Reports Server (NTRS)

An overview of the present state of the art in the different scientific and technological fields related to spaceborne imaging radars was presented. The data acquired with the SEASAT SAR (1978) and Shuttle Imaging Radar, SIR-A (1981) clearly demonstrated the important emphasis in the 80's is going to be on in-depth research investigations conducted with the more flexible and sophisticated SIR series instruments and on long term monitoring of geophysical phenomena conducted from free-flying platforms such as ERS-1 and RADARSAT.

Elachi, C.

1983-01-01

454

A controlled experiment to retrieve freshwater ice characteristics from an FM-CW radar system  

Microsoft Academic Search

A controlled experiment was conducted at the Cold Region Research and Engineering Laboratory (CRREL) facilities for retrieving freshwater ice characteristics using a Frequency Modulated Continuous Wave (FM-CW) radar system. The purpose of this study is to quantify the interactions between a backscattered radar signal and ice cover characteristics such as thickness and air bubble content; and to provide a comprehensive

R. Leconte; S. Daly; Y. Gauthier; N. Yankielun; F. Brub; M. Bernier

2009-01-01

455

Improved detection and suppression of external interference in HF Surface Wave Radar  

Microsoft Academic Search

This paper presents a propagation-attenuation-model-based method to detect the ranges where ionospherically distorted signals in HF Surface Wave Radar (HFSWR) may become dominant. While the method can be used to detect the presence of both ionospheric clutter and skywave interference, this paper focuses on the detection of skywave interference only. The radar data in the detected ranges where skywave interference

Hank Leong

2011-01-01

456

The HF surface wave radar WERA. Part I: Statistical analysis of recorded data  

Microsoft Academic Search

Surface wave (SW) over-the-horizon (OTH) radars are not only widely used for ocean remote sensing, but they can also be exploited in integrated maritime surveillance systems. This paper represents the first part of the description of the statistical and spectral analysis performed on sea backscattered signals recorded by the oceanographic WEllen RAdar (WERA) system. Data were collected on May 13th

Salvatore Maresca; Maria Greco; Fulvio Gini; R. Grasso; S. Coraluppi; N. Thomas

2010-01-01

457

Comparison of raindrop size distributions measured by radar wind profiler and by airplane  

Microsoft Academic Search

Wind profilers are radars that operate in the VHF and UHF bands and are designed for detecting the weak echoes reflected by the optically clear atmosphere. An unexpected application of wind profilers has been the revival of an old method of estimating drop size distributions in rain from the Doppler spectrum of the received signal. Originally attempted with radars operating

R. R. Rogers; S. A. Ethier; D. Baumgardner; D. A. Carter; W. L. Ecklund

1993-01-01

458

Target detection in high clutter using passive bistatic WiFi radar  

Microsoft Academic Search

The rapid rollout of wireless local area networks (WLANs) has provided a ubiquitous source of signal transmissions that may be exploited for surveillance applications using passive bistatic radar (PBR) and passive multistatic radar (PMR) systems. In this study, a series of experiments were conducted to examine the feasibility of using IEEE 802.11 wireless fidelity (WiFi) transmissions for detecting uncooperative targets

Kevin Chetty; Graeme Smith; Hui Guo; Karl Woodbridge

2009-01-01

459

Title: Satellite Radar Interferometry in the Earth Sciences Instructor: Falk Amelung  

E-print Network

: Systems and Signal Processing (Wiley Series in Remote Sensing and Image Processing) By John C. CurlanderTitle: Satellite Radar Interferometry in the Earth Sciences Instructor: Falk Amelung Credits: 3 and differential interferometric radar techniques. Students will learn how SAR images and SAR interferograms

Miami, University of

460

High speed data acquisition systems for ISRO's airborne and spaceborne radars  

Microsoft Academic Search

During 1990's, high speed data handling and control unit (DHCU) was developed for Indian Space Research Organisation's (ISRO) C-band airborne synthetic aperture radar (ASAR) at Space Applications Centre (SAC), ISRO, India. It has been extensively utilised to acquire high bandwidth radar signal during ASAR flights aboard Beechcraft-200 aircraft, conducted regularly since 1997. DHCU supports ASAR data acquisition, formatting and storage.

N. M. Desai; R. Agrawal; J. G. Vachhani; V. R. Gujraty; S. S. Rana

2003-01-01

461

Algorithms of processing of radar images in radio vision systems of the car  

Microsoft Academic Search

In the report results of researches of algorithms of secondary processing of radar images (RI) in radiovision system of automobile (ARVS) are presented. ARVS is panoramic radar of the forward review with frequency modulation (FM) of a probing signal of MM wavelength. By development of algorithms following features of RI formation are considered: the sizes of the image, system of

Andrey Ananenkov; Anton Konovaltsev; Vladimir Nujdin; Vladimir Rastorguev; Pavel Sokolov

2009-01-01

462

Preliminary analysis of LACE vibrations as observed with Doppler laser radar  

Microsoft Academic Search

Vibration signatures from the Low Power Atmospheric Compensation (LACE) satellite were obtained from the ground based Firepond coherent CO2 laser radar operated by MIT Lincoln Laboratory. The LACE spacecraft has three germanium corner reflectors, mounted on the base and at the ends of deployable\\/retractable booms to enable detection of the return signal. Analysis of pulsed CW Doppler radar provides measurements

S. Fisher; K. I. Schultz

1992-01-01

463

Normalized radar cross section of the sea for backscatter: 1. Mean levels  

Microsoft Academic Search

The normalized radar cross section of the sea for backscatter, ?o, is investigated for incidence angles between 0 and 89 using data collected over more than two decades. The most recent measurements were made from several ships using a coherent, dual-polarized, X band radar. These measurements show that vertically polarized transmit and receive signals, ?o(VV), at high incidence angles exhibit

William J. Plant; William C. Keller; Kenneth Hayes; Gene Chatham

2010-01-01

464

Detection of subsurface non-metallic objects using stepped frequency continuous wave ground penetrating radar  

Microsoft Academic Search

In the paper, several aspects of using stepped frequency continuous wave signal in a ground penetrating radar were discussed. Radar was operating in 7503000 MHz bandwidth, with 563 frequency steps. Test objects included non-metallic object made from wood and plastic, as well as soil with different value of permittivity, all buried at 1015 cm.

Pawel Kaczmarek; Marian Lapinski; Janusz Karczewski

2010-01-01

465

Comparison of algorithms for land mine detection and discrimination using ground penetrating radar  

Microsoft Academic Search

Ground penetrating radar (GPR) has been proposed as an effective sensing modality for reducing the excessively high false alarm rates often encountered in landmine detection applications. Ground penetrating radar is sensitive to discontinuities in the interrogated medium, rather than the presence of metal, and thus exploits a different phenomenology than electromagnetic induction (EMI) sensors. Thus, unique signals that are dependent

Stacy L. Tantum; Yuchuan Wei; Vivek S. Munshi; Leslie M. Collins

2002-01-01

466

BYU MICRO-SAR: A VERY SMALL, LOW-POWER LFM-CW SYNTHETIC APERTURE RADAR  

E-print Network

BYU MICRO-SAR: A VERY SMALL, LOW-POWER LFM-CW SYNTHETIC APERTURE RADAR by Michael I. Duersch-SAR: A VERY SMALL, LOW-POWER LFM-CW SYNTHETIC APERTURE RADAR Michael I. Duersch Department of Electrical these constraints, a linear frequency modulation- continuous wave (LFM-CW) transmit signal is utilized. Use

Long, David G.

467

A traffic radar verification system based on GPSDoppler technology  

Microsoft Academic Search

In this article, a traffic radar verification system based on the GPSDoppler technology is described. An speedometer boarded in the target vehicle estimates its speed from the Doppler variation of the GPS satellites signals, and transmits it via radio to the police vehicle, where the radar to verify is located. In order to automate the procedure and be more effective,

Soledad Torres-Guijarro; Esteban Vzquez-Fernndez; Miguel Seoane-Seoane; J. Alfonso Mondaray-Zafrilla

2010-01-01