Sample records for radar emitter signals

  1. Specific Emitter Identification: Analysis on real radar signal data

    Microsoft Academic Search

    S. D'Agostino; G. Foglia; D. Pistoia

    2009-01-01

    This paper focuses on the specific emitter identification (SEI) technique applied to electronic support measure (ESM) systems. The main idea is to analyze the radar pulses and characterize those by extracting features that should be different for each radar. In the paper, feature extraction algorithms are used to characterize the radar pulses: a measurement campaign has been conducted to acquire

  2. Radar background signal reduction study

    Microsoft Academic Search

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

    1980-01-01

    This report summarizes a study whose objective was to identify materials and\\/or techniques to reduce radar background signals for ground plane radar cross section (RCS) ranges. Background signal reduction is essential for improving the accuracy of RCS measurements and the primary application is for operations at the RATSCAT range on the White Sands Missile Range in New Mexico. A survey

  3. Radar signal categorization using a neural network

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

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

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

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

  5. Multistatic radar systems signal processing

    Microsoft Academic Search

    I. Bradaric; G. T. Capraro; D. D. Weiner; M. C. Wicks

    2006-01-01

    In this paper, a multistatic radar system with multiple receivers and one transmitter is analyzed. We address the rules for selecting the weights for fusing multiple receivers in order to meet pre-specified performance goals. A multistatic radar ambiguity function is used to relate different radar performance measures to system parameters such as radar geometry and radar waveforms. Simulations are used

  6. On Probing Signal Design For MIMO Radar

    Microsoft Academic Search

    Petre Stoica; Jian Li; Yao Xie

    2007-01-01

    A multiple-input multiple-output (MIMO) radar system, unlike a standard phased-array radar, can choose freely the probing signals transmitted via its antennas to maximize the power around the locations of the targets of interest, or more generally to approximate a given transmit beampattern, and also to minimize the cross-correlation of the signals reflected back to the radar by the targets of

  7. On Probing Signal Design for MIMO Radar

    Microsoft Academic Search

    Jian Li; Petre Stoica; Yao Xie

    2006-01-01

    A MIMO (multi-input multi-output) radar system, unlike a standard phased-array radar, can choose freely the probing signals transmitted via its antennas to maximize the power around the locations of the targets of interest, or more generally to approximate a given transmit beampattern, and also to minimize the cross-correlation of the signals reflected back to the radar by the targets of

  8. Weather Radar signals with Alpha Stable Distributions

    Microsoft Academic Search

    M LAGHA

    This work, treats about a modeling of the weather precipitation echoes detected by a weather pulse Doppler radar. The methods used for the simulation of the Doppler spectrum, and I & Q signals representing the precipitations radar echoes, is based on a macroscopic models, i.e. random processes with assigned spectra. We propose global model, with a power spectrum having a

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

    NASA Astrophysics Data System (ADS)

    Cedrina, Lorena; Bonomo, Néstor; Osella, Ana

    2010-03-01

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

  10. How to Reconstruct the Original Shape of a Radar Signal?

    E-print Network

    Kreinovich, Vladik

    How to Reconstruct the Original Shape of a Radar Signal? Matthew G. Averill, Gang Xiang, Vladik Abstract--- The shape of the radar signal can provide us with the additional information about the reflecting surface. However, to decrease the noise, radars use filtering, and filtering changes the shapes

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

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

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

  12. Physics-based airborne GMTI radar signal processing

    Microsoft Academic Search

    George R. Legters; Joseph R. Guerci

    2004-01-01

    The Knowledge-Aided Sensor Signal Processing and Expert Reasoning (KASSPER) program aims to improve airborne ground moving target indicator (GMTI) radar performance by taking into account all available prior knowledge. One powerful piece of information is that the radar return signal is a superposition of near-ideal plane-waves. A plane-wave signal and clutter model or sampled GMTI radar data can be used

  13. Detection and Parameter Estimiation of LPI Signals in Passive Radar

    Microsoft Academic Search

    Xiaoming Tang; Benqing Jiang; Caisheng Zhang; You He

    2006-01-01

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

  14. Radar transponder apparatus and signal processing technique

    DOEpatents

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

    1996-01-23

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

  15. Radar transponder apparatus and signal processing technique

    DOEpatents

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

    1996-01-01

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

  16. Radar transponder apparatus and signal processing technique

    SciTech Connect

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

    1994-12-31

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

  17. Digital signal processing techniques in a monopulse tracking radar

    Microsoft Academic Search

    U. Fazio; F. Ambrosioni; C. Debonis

    1979-01-01

    A description of a special-purpose Signal Processor is given. Since the Processor is highly flexible, it can be applied in a wide range of modern ground or ship-borne tracking radars, such as, Fire Control Radar for rockets or for conventional artillery (ground or anti-aircraft), Instrumentation Radar, and Tracking Radar for Command to line-of-sight missile guidance. Illustrated are the three main

  18. Auxiliary signal processing system for a multiparameter radar

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  19. Signal to Noise Analysis of iRadar sensors

    SciTech Connect

    Fritzke, A; Top, P

    2009-09-10

    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.

  20. Nonsinusoidal radar signal design for stealth targets

    Microsoft Academic Search

    Nasser J. Mohamed

    1995-01-01

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

  1. Joint Time-Frequency Analysis of Ultra Wideband Radar Signals

    Microsoft Academic Search

    Hoi-Shun Lui; Nicholas V. Z. Shuley

    The time variant nature of an Ultra-Wideband (UWB) radar signal scattered from a radar target is well described throughout the literature. To study the behaviour of these transient signals, Joint Time-Frequency (TF) analysis is considered. Various Time-Frequency Distributions (TFDs) have been developed in the signal processing area over the last twenty years but little work has been done in a

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

    NASA Technical Reports Server (NTRS)

    Rosen, Paul A.

    2012-01-01

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

  3. Signal processing and waveform selection strategies in multistatic radar systems

    Microsoft Academic Search

    Ivan Bradaric; Gerard T. Capraro; Michael C. Wicks; Peter Zulch

    2007-01-01

    The multistatic ambiguity function has recently been used as a tool for analyzing multistatic radar systems. It was demonstrated that the multistatic ambiguity function with proper analytical foundation and corresponding graphic representation can serve as a guideline for developing multistatic radar signal processing rules. In this work we use this newly developed approach to combine optimal selection of weights for

  4. Digital signal processing in binary phase coded CW multistatic radar

    Microsoft Academic Search

    R. Norland

    2003-01-01

    Electronic countermeasures (ECM) and homing anti-radiation missiles (ARM) pose a threat to the operability of radar. One solution to counteract the threat and continue operating radar is to separate the transmitter and receiver and spread the emitted signal in both frequency and space. The Norwegian Defence Research Establishment (FFI) has developed a low power, bistatic, coherent, spread spectrum and continuous

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

    E-print Network

    Paris-Sud XI, Université de

    1 Sparse detection in the chirplet transform: application to FMCW radar signals Fabien Millioz Modulation Continuous Wave radars. The radar signals are made of piecewise linear frequency modulations. An illustration is provided on synthetic data. Index Terms--LPI radar, FMCW radar, chirplet transform, parameter

  6. WiMAX signal waveform analysis for passive radar application

    Microsoft Academic Search

    Qing Wang; Chunping Hou; Yilong Lu

    2009-01-01

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

  7. Time-frequency analysis of synthetic aperture radar signals

    SciTech Connect

    Johnston, B.

    1996-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  9. Doppler radar with multiphase modulation of transmitted and reflected signal

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  10. Automatic signal processing of front monitor radar for tunneling machines

    SciTech Connect

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

    1997-03-01

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

  11. Analysis of Human Gait Radar Signal Using Reassigned WVD

    NASA Astrophysics Data System (ADS)

    Zhang, Jun

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

  12. Study on velocity estimation of MCPC signal in wideband radar

    Microsoft Academic Search

    Bin Sun; Xi-zhang Wei; Xiang Li

    2010-01-01

    This paper presents a novel scheme for velocity estimation in wideband Multi-Carrier Phase-Coded (MCPC) radar, which has drawn considerable attention recently as a new generation of radar. Conventional narrowband Doppler processing preserves the phase relationship of the received pulses, thus not only increases the Signal-to-Noise Ratio (SNR), but also obtains reliable extraction of the Doppler parameters. However, the rangewalk of

  13. Quasi-optimal signal processing in ground Forward Scattering Radar

    Microsoft Academic Search

    Cheng Hu; M. Antoniou; M. Cherniakov; V. Sizov

    2008-01-01

    A signal processing algorithm for ground target detection using forward scattering radar (FSR) is presented in this paper. The effectiveness of the algorithm is shown using both simulated and experimental data. The algorithm is based on the matched filtering approach, where the correlation between the received signal and a set of pre-defined reference functions is calculated. The maximum of the

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

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

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

  15. Minimum Detectable Radar Signal and Its Dependence upon Parameters of Radar Systems

    Microsoft Academic Search

    A. V. Haeff

    1946-01-01

    This paper presents results of an early study of the influence of parameters of a pulse radar system on its sensitivity. More specifically, it describes an experimental determination of the absolute value of minimum pulse signal visually detectable through random noise with a probability of 50 per cent for a wide range of the following parameters: pulse-repetition rate r, pulse

  16. Signal Generation for FMCW Ultra-Wideband Radar

    E-print Network

    Patel, Aqsa Ejaz

    2009-01-01

    . The main objective of the thesis was to produce an ultra linear transmit chirp signal for UWB Radars. This was done by using the Voltage-Controlled-Oscillator (VCO) in a Phase-Locked Loop configuration. To check the linearity of the chirp beat frequency...

  17. Application of LSS-decomposition in weather radar signal processing

    Microsoft Academic Search

    O. S. Semenova; F. J. Yanovsky; I. V. Shelevytsky

    2012-01-01

    In this paper new approach for weather radar signal analysis and dangerous meteorological zones detection is discussed. It is based on time-frequency LSS decomposition. In order to provide reliable information about the object location and its intensity, the confidence intervals calculation is fulfilled.

  18. INTRODUCTION TO RADAR SIGNAL & DATA PROCESSING : THE OPPORTUNITY

    Microsoft Academic Search

    A. Farina

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

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

    E-print Network

    Xie, Yao

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

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

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

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

  1. Radar antenna pointing for optimized signal to noise ratio.

    SciTech Connect

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

    2013-01-01

    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.

  2. Passive radar in the high frequency band

    Microsoft Academic Search

    Giuseppe Fabrizio; Fabiola Colone; Pierfrancesco Lombardo; Alfonso Farina

    2008-01-01

    Passive radar systems using emitters of opportunity for target detection and tracking have received significant interest recently, especially those which exploit frequency modulated (FM) radio stations and TV transmitters as signal sources. This paper is concerned with passive radar systems that utilize signal sources in the high frequency (HF) band (3-30 MHz), where due to long-distance ionospheric propagation, the transmitter

  3. Atmospheric Radar Signal Processing using Bivariate Empirical Mode Decomposition

    NASA Astrophysics Data System (ADS)

    Sreenivasulu Reddy, Thatiparthi

    2012-07-01

    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.

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

    E-print Network

    Grossberg, Stephen

    in the field. Meanwhile, a clustering algorithm is used to separate pulses from different emitters according-and-Where fusion strategy is motivated by a similar subdivision of labor in the brain. The fuzzy ARTMAP neural the search for, interception, location, anal- ysis and identification of radiated electromagnetic energy

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

    E-print Network

    Grossberg, Stephen

    collected in the field. Meanwhile, a clustering algorithm is used to separate pulses from different emitters trajectory. Such a What­and­Where fusion strategy is motivated by a similar subdivision of labor in the brain and identification of radiated electromagnetic energy for military purposes. ESM hereby provide valuable information

  6. Digital Radar-Signal Processors Implemented in FPGAs

    NASA Technical Reports Server (NTRS)

    Berkun, Andrew; Andraka, Ray

    2004-01-01

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

  7. Signal based motion compensation for synthetic aperture radar

    SciTech Connect

    John Kirk

    1999-06-07

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

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

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

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

  9. Signal Processing Algorithms for the Terminal Doppler Weather Radar: Build 2

    E-print Network

    Cho, John Y. N.

    Signal Processing Algorithms for the Terminal Doppler Weather Radar: Build 2 February 21, 2010 John to the public through the National Technical Information Service, Springfield, VA 22161 Signal Processing) was developed for the Terminal Doppler Weather Radar (TDWR), enhanced signal processing algorithms taking

  10. Knowledge-based radar signal and data processing: a tutorial review

    Microsoft Academic Search

    Gerard T. Capraro; Alfonso Farina; Hugh Griffiths; Michael C. Wicks

    2006-01-01

    Radar systems are an important component in military operations. In response to increasingly severe threats from military targets with reduced radar cross sections (RCSs), slow-moving and low-flying aircraft hidden in foliage, and in environments with large numbers of targets, knowledge-based (KB) signal and data processing techniques offer the promise of significantly improved performance of all radar systems. Radars under KB

  11. Signal extraction using Compressed Sensing for passive radar with OFDM signals

    Microsoft Academic Search

    Christian R. Berger; Shengli Zhou; Peter Willett

    2008-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Fairchild, Dustin P.; Narayanan, Ram M.

    2014-06-01

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

  13. 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

  14. Reliability of detection of radar signals from hailstones by using parametric and non-parametric algorithms

    Microsoft Academic Search

    Felix J. Yanovsky; Rustem B. Sinitsyn; Igor M. Braun

    2005-01-01

    New algorithms for polarimetric radar signals processing were developed and applied for the detection of hail zones in clouds and precipitation. This paper presents and analyzes two algorithms: parametric algorithm and adaptive non-parametric algorithm. Reliability of detection of radar signals from hailstones is investigated by statistical simulation with application of experimental researches as initial data. The results demonstrate the limits

  15. Bistatic coherent laser radar signal-to-noise ratio.

    PubMed

    Magee, Eric P; Kane, Timothy J

    2002-03-20

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

  16. Virtual hyperbolic metamaterials for manipulating radar signals in air.

    PubMed

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

    2013-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Mohamed, Nasser J.

    1990-05-01

    A generalization of a previously published ambiguity function that applies to radar known as large-relative-bandwidth radar, carrier-free radar, impulse radar, or nonsinusoidal radar is discussed. This radar has recently attracted attention because of its ability to penetrate absorbing materials used in the stealth technology. Another good application is the detection of moving targets with a small radar cross section by a look-down radar, which calls for a thumbtack ambiguity function. Since a small radar cross section in this application is typically due to the small size of the target that is coated with absorbing material, the antistealth feature of the nonsinusoidal radar is implicitly being used. The principle is presented of a resolution function (tentatively called the range-velocity or the range-Doppler resolution function) based on processing a nonsinusoidal signal consisting of N characters with a time separation TD and each character consisting of a sequence of L binary pulses of duration T. It is shown that range-velocity resolution functions approaching the ideal thumbtack function are easy to obtain. The blind speeds of the pulse-Doppler radar with sinusoidal carrier do not inherently occur, and all velocities are observed as true velocities rather than as velocities modulo the first blind speed (velocity ambiguity).

  18. Feature parameter extraction approach with the stealth S-Cubed radar signal

    Microsoft Academic Search

    Zeng Xiao-dong; Xiong Ying; Zhang Wei; Zeng De-guo; Li Yong-ping; Luo Shuang-cai; Tang Bin

    2011-01-01

    Radar equipments of stealth platforms such as aircrafts have adopted the newest modern technology to design the signal waveforms. One of the important and effective methods is the hybrid stealth radar waveform called spread spectrum stretch (S-Cubed). In this paper, the model of S-Cubed which combines linear frequency modulation (LFM) and discrete phase code is presented. Then, a novel approach

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

    E-print Network

    Stoffelen, Ad

    to solar flux units and then compared to observations from the DRAO solar flux monitoring station in Canada- gular biases of the radar antenna using solar signals observed by a scanning weather radar (Huuskonen and data are shown in Figures 1 and 2. III. CONVERSION OF REFLECTIVITY TO SOLAR FLUX A consistent

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

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

  2. Optimal Signal Processing of Frequency-Stepped CW Radar Data

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    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.

  3. Optimal Signal Processing of Frequency-Stepped CW Radar Data

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    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.

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

    E-print Network

    Cho, John Y. N.

    Multi-PRI Signal Processing for the Terminal Doppler Weather Radar. Part I: Clutter Filtering JOHN (Cho et al. 2003). Multi-PRI signals can be processed to effectively sepa- rate different-trip weather Multiple pulse repetition interval (multi-PRI) transmission is part of an adaptive signal transmission

  5. Microwave Human Vocal Vibration Signal Detection Based on Doppler Radar Technology

    Microsoft Academic Search

    Chien-San Lin; Sheng-Fuh Chang; Chia-Chan Chang; Chun-Chi Lin

    2010-01-01

    A speech radar system is presented for extracting speech information from the vocal vibration signal of a human subject. Due to the tiny glottis motion of several millimeters, a coherent homodyne demodulator with high sensitivity is developed to detect reflected radio signal, phase modulated by the vibrating vocal cords. The signal detection quality and system circuit design are described. Measurements

  6. Radar signal pre-processing to suppress surface bounce and multipath

    DOEpatents

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

    2013-12-31

    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.

  7. Waveform Diversity and Range-Coupled Adaptive Radar Signal Processing

    E-print Network

    Higgins, Thomas

    2011-12-31

    Waveform diversity may offer several benefits to radar systems though often at the cost of reduced sensitivity. Multi-dimensional processing schemes are known to offer many degrees of freedom, which can be exploited to suppress the ambiguity...

  8. Earth curvature and atmospheric refraction effects on radar signal propagation.

    SciTech Connect

    Doerry, Armin Walter

    2013-01-01

    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.

  9. Radar

    Microsoft Academic Search

    James R. Zimbelman; Kenneth S. Edgett

    1994-01-01

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

  10. Through-Wall Radar Image Reconstruction Based on Time-Domain Transient Signals in the Presence of

    E-print Network

    Doran, Simon J.

    Through-Wall Radar Image Reconstruction Based on Time-Domain Transient Signals in the Presence Technological University, Nanyang Avenue, Singapore 639798 etsho@ntu.edu.sg Abstract Through-wall radar imaging counter-terrorism. Other applications of through-wall radar imaging include urban warfare, hostage rescue

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

    E-print Network

    Luh, Peter

    IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 60, NO.2, FEBRUARY 2012 687 The MIMO Radar and Jammer, and Peter B, Luh, Fellow, IEEE Abstract-The interaction between a smart target and a smart MIMO radar is investigated from a game theory perspective. Since the target and the radar form an adversarial system

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

    Microsoft Academic Search

    Rossano Pardini; Umberto Bruno; Roberto Izzo

    2009-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Weissman, David E.; Staton, Leo D.

    1991-01-01

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

  14. Definition and fabrication of an airborne scatterometer radar signal processor

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A hardware/software system which incorporates a microprocessor design and software for the calculation of normalized radar cross section in real time was developed. Interface is provided to decommutate the NASA ADAS data stream for aircraft parameters used in processing and to provide output in the form of strip chart and pcm compatible data recording.

  15. Analysis of phase relationships between radar signals in acoustooptic processing systems

    Microsoft Academic Search

    M. V. D’yakonov; T. F. Faîsullov; T. T. Sultanov; A. F. Tavasiev; A. N. Torgashin; V. A. Zubov

    1997-01-01

    The performance and the salient operation features of an interference correlator with a modified optical twin-wave Rayleigh\\u000a interferometer system in the mode of measurements of phase shifts between radar signals are considered. Such measurements\\u000a for signals received from two antennas provide information on the angular position of an object or its displacement. A system\\u000a wherein radio signals are fed for

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

    Microsoft Academic Search

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

    2004-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Bolen, Steven M.; Chandrasekar, V.

    2003-06-01

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

  18. Signal processing technique for removal of NUBF-induced error in spaceborne Doppler precipitation radar measurements

    NASA Astrophysics Data System (ADS)

    Tanelli, Simone; Im, Eastwood; Facheris, Luca; Durden, Stephen L.

    2002-02-01

    A sampling strategy and a signal processing technique are proposed to overcome Non Uniform Beam Filling (NUBF) errors on mean Doppler velocity measurements made by spaceborne weather radars. Effects of non uniformity of rainfall within the main antenna lobe in terms on the accuracy of standard estimators are first briefly shown, so as to point out that the bias introduced by NUBF on mean Doppler velocity estimates can be greater than the standard deviation of the estimated velocity, and that it depends on the along-track distribution of reflectivity. Then the sampling strategy is described, based on an oversampling of the integrated data in the along-track direction in order to retrieve information about the reflectivity pattern at the sub-beam scale. The proposed processing technique, named Combined Frequency-Time (CFT) technique, exploits the time series of spectra at fixed range to resolve the NUBF induced bias. The results and the evaluation of performances achievable by means of CFT, were obtained by applying a 3D spaceborne Doppler radar simulator to a 3D dataset of reflectivity and mean Doppler velocity measured through the NASA/JPL airborne Doppler radar ARMAR. The radar system considered here is a nadir-looking, Ku band radar with a sufficiently wide antenna. It is shown how the error on mean Doppler velocity estimates can be reduced by means of CFT to the level predicted for such a radar system in the case of uniformly filled resolution volume (UBF).

  19. The modification of X and L band radar signals by monomolecular sea slicks

    Microsoft Academic Search

    Heinrich Hühnerfuss; Werner Alpers; Aubrey Cross; William D. Garrett; William C. Keller; William J. Plant; Dale L. Schuler; Philipp A. Lange; Franz Schlude

    1983-01-01

    One methyl oleate and two oleyl alcohol surface films were produced on the surface of the North Sea under comparable oceanographic and meteorological conditions in order to investigate their influence on X and L band radar backscatter. Signals are backscattered in these bands primarily by surface waves with lengths of about 2 and 12 cm, respectively, and backscattered power levels

  20. Radar wind profiler signal characteristics during bird migration episodes Volker Lehmann1 and Gerd Teschke2

    E-print Network

    Teschke, Gerd

    generate such clutter signals. Birds are effective targets for a wide range of radars from X-band to UHF on wavelength and antenna characteristics. It mostly affects L-band and UHF-systems, that is Boundary Layer profilers (RWP) are being widely used for measuring wind velocities in the atmosphere. Recent reviews

  1. Improvement of radar target searches by a range dependent detection threshold or signal amplification

    Microsoft Academic Search

    E. Hanle

    1980-01-01

    The impact of signal amplification on the search for targets with different radar cross sections was studied. A clear presentation of the whole range dependence with minimum computing expense was obtained by restriction to single pulse operation. Through a suitable range controlled threshold with half the transmitting energy, the same detection probability at maximum range is obtained as with a

  2. Signal processor interface simulation of the AN\\/SPY1A radar controller

    Microsoft Academic Search

    T. B. Kersh

    1983-01-01

    This thesis reports on the design and implementation of a simulation of the Signal Processor Interface to the AN\\/SPY-1A Phased Array Radar Controller. Inherent to the simulation is the development of a representative time sensitive database of the targeting environment. The programming language Ada was utilized as a program development language in the design for the database. The developed Target

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    PubMed

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

    2010-01-01

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

  5. Comparison between backscattered TerraSAR signals and simulations from the radar backscattering models IEM, Oh, and Dubois

    E-print Network

    Paris-Sud XI, Université de

    link the radar backscattering coefficient to soil parameters (dielectric constant, roughness1 1 Comparison between backscattered TerraSAR signals and simulations from the radar backscattering.baghdadi@teledetection.fr Tel.: 33 4 67 54 87 24; Fax: 33 4 67 54 87 00 The objective of this paper is to evaluate on bare soils

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

    NASA Technical Reports Server (NTRS)

    Frehlich, Rod

    1993-01-01

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

  7. Resolution function of nonsinusoidal radar signals. II - Range-velocity resolution with pulse compression techniques

    NASA Astrophysics Data System (ADS)

    Mohamed, Nasser J.

    1991-02-01

    The thumbtack range-velocity resolution function of nonsinusoidal radar signals has been realized with signals having a large number of characters with triangular correlation functions. In reality, a radar signal rarely consists of one pulse; rather, it consists of thousands of pulses structured by various coding techniques. Pulse compression is a technique for obtaining high range resolution with long coded signals. The thumbtack range-velocity resolution function based on the pulse compression principle is realized by coding the transmitted signal using complementary codes. The correlation function of the coded signal is characterized by a main triangular lobe, a sidelobe-free region, and time sidelobes. Increasing the code length will increase the pulse compression ratio and the time-sidelobe-free region. Doppler processing of correlation functions based on the pulse compression technique can realize the thumbtack range-velocity resolution function. The range-velocity resolution function is obtained by computer simulation and represented by a three-dimensional surface as a function of target range and velocity for signals with a different number of characters. Plots of range-velocity resolution functions for characters with different code lengths are presented.

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

    Microsoft Academic Search

    WILLIAM L. MELVIN; JOSEPH R. GUERCI

    2006-01-01

    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

  9. THREE-FREQUENCY HETERODYNE SYSTEM FOR ACQUISITION AND TRACKING OF RADAR AND COMMUNICATIONS SIGNALS

    Microsoft Academic Search

    M. C. Teich

    1969-01-01

    The operation of a three-frequency heterodyne system for communications and radar use is discussed. The technique provides important advantages over the conventional heterodyne detector, and is applicable in the infrared, optical, and microwave. The signal-to-noise ratio and minimum detectable power for the specific case of an optical or infrared system are calculated and compared with values for the standard configuration.

  10. Short Range Radar Signal Processing for Lateral Collision Warning in Road Traffic Scenarios

    Microsoft Academic Search

    Dirk Bank

    2007-01-01

    This paper introduces signal processing algorithms of single-sensor-multi-target-tracking, sensor data fusion, and multi-sensor-multi-target-tracking developed for designing a novel lateral collision warning function. In order to improve the perception of road vehicles, an experimental vehicle has been equipped with arrays of three short range radar sensors on both sides. With the aid of such sensor arrangements, lateral objects (e.g. cars, trucks,

  11. Model-Based Information Extraction From Synthetic Aperture Radar Signals

    NASA Astrophysics Data System (ADS)

    Matzner, Shari A.

    2011-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  14. Computer simulation of the RF system effects on a millimeter-wave Doppler radar for human vital-signal estimation

    Microsoft Academic Search

    Pi-Hsien Lien; Fu-Lin Lin; Huey-Ru Chuang

    2009-01-01

    A detailed modeling and analysis for the effect of the RF system on the human vital-signal estimation by a 60-GHz millimeter-wave Doppler radar has been developed. The simulation scheme uses the root-MUSIC algorithm to calculate the frequency error ratios of the estimated heartbeat and breathing signals by the radar detection system. From the simulation results, it is found that root-MUSIC

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    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.

  16. Real-time signal construction and digital quadrature modulation for pulse Doppler radar clutter

    NASA Astrophysics Data System (ADS)

    Liang, Zhiheng; Xu, Jiaxiang; Chen, Xunda

    2001-08-01

    The signal processors in pulse Doppler radar can detect the target signal which is spectrally separated from clutter, even if the signal is -60 dB weaker or more than main- lobe clutter, so in missile hardware-in-the-loop it is required that the noise resulted by clutter reconstruction architecture should be -60 dB lower than main-lobe clutter. Because of the restriction, a new method of clutter reconstruction with specific power spectrum is proposed, which include conversion from power spectrum to vector spectrum, randomization of phase, inverse Fourier transform, and then windowing and overlapping the series time domain sequence, which guarantee the expectation value and variance of random sequence continuously. The simulation results demonstrate that by applying the method, the ratio of signal to noise is increased from 30 dB to 60 dB.

  17. Quantifying the accuracy of snow water equivalent estimates using broadband radar signal phase

    NASA Astrophysics Data System (ADS)

    Deeb, E. J.; Marshall, H. P.; Lamie, N. J.; Arcone, S. A.

    2014-12-01

    Radar wave velocity in dry snow depends solely on density. Consequently, ground-based pulsed systems can be used to accurately measure snow depth and snow water equivalent (SWE) using signal travel-time, along with manual depth-probing for signal velocity calibration. Travel-time measurements require a large bandwidth pulse not possible in airborne/space-borne platforms. In addition, radar backscatter from snow cover is sensitive to grain size and to a lesser extent roughness of layers at current/proposed satellite-based frequencies (~ 8 - 18 GHz), complicating inversion for SWE. Therefore, accurate retrievals of SWE still require local calibration due to this sensitivity to microstructure and layering. Conversely, satellite radar interferometry, which senses the difference in signal phase between acquisitions, has shown a potential relationship with SWE at lower frequencies (~ 1 - 5 GHz) because the phase of the snow-refracted signal is sensitive to depth and dielectric properties of the snowpack, as opposed to its microstructure and stratigraphy. We have constructed a lab-based, experimental test bed to quantify the change in radar phase over a wide range of frequencies for varying depths of dry quartz sand, a material dielectrically similar to dry snow. We use a laboratory grade Vector Network Analyzer (0.01 - 25.6 GHz) and a pair of antennae mounted on a trolley over the test bed to measure amplitude and phase repeatedly/accurately at many frequencies. Using ground-based LiDAR instrumentation, we collect a coordinated high-resolution digital surface model (DSM) of the test bed and subsequent depth surfaces with which to compare the radar record of changes in phase. Our plans to transition this methodology to a field deployment during winter 2014-2015 using precision pan/tilt instrumentation will also be presented, as well as applications to airborne and space-borne platforms toward the estimation of SWE at high spatial resolution (on the order of meters) over large regions (> 100 square kilometers).

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

    Microsoft Academic Search

    Nasser J. Mohamed

    1990-01-01

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

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

    Microsoft Academic Search

    N. J. Mohamed

    1990-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Gaballah, Mahmoud; Sato, Motoyuki

    2009-02-01

    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.

  1. Estimating the impulse response of buried objects from ground-penetrating radar signals

    NASA Astrophysics Data System (ADS)

    van der Lijn, Fedde; Roth, Friedrich; Verhaegen, Michel

    2003-09-01

    This paper presents a novel deconvolution algorithm designed to estimate the impulse response of buried objects based on ground penetrating radar (GPR) signals. The impulse response is a rich source of information about the buried object and therefore very useful for intelligent signal processing of GPR data. For example, it can be used in a target classification scheme to reduce the false alarm rate in demining operations. Estimating the target impulse response from the incident and scattered radar signals is a basic deconvolution problem. However, noise sensitivity and ground dispersion prevent the use of simple deconvolution methods like linear least squares deconvolution. Instead, a new deconvolution algorithm has been developed that computes estimates adhering to a physical impulse response model and that can be characterized by a limited number of parameters. It is shown that the new algorithm is robust with respect to noise and that it can deal with ground dispersion. The general performance of the algorithm has been tested on data generated by finite-difference time-domain (FDTD) simulations. The results demonstrate that the algorithm can distinguish between different dielectric and metal targets, making it very suitable for use in a classification scheme. Moreover, since the estimated impulse responses have physical meaning they can be related to target characteristics such as size and material properties. A direct application of this is the estimation of the permittivity of a dielectric target from its impulse response and that of a calibration target.

  2. Time and frequency synchronization in multistatic radar. Consequences to usage of GPS disciplined references with and without GPS signals

    Microsoft Academic Search

    Terje Johnsen

    2002-01-01

    The use of time and frequency references disciplined to GPS has been studied in the context of use in multistatic radar. Several reference units with civilian GPS receivers were tested. Differences in 1PPS fluctuations were observed that would result in ranging errors when stable GPS signals were received. If GPS signals were lost further control of reference output depends on

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

    PubMed Central

    Wang, Wei; Mandelis, Andreas

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    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.

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

    Microsoft Academic Search

    Steven M. Bolen; V. Chandrasekar

    2003-01-01

    The Tropical Rainfall Mapping Mission (TRMM) is the first mission dedicated to measuring rainfall from space using radar. The precipitation radar (PR) is one of several instruments aboard the TRMM satellite that is operating in a nearly circular orbit with nominal altitude of 350 km, inclination of 35°, and period of 91.5 min. The PR is a single-frequency Ku-band instrument

  6. Active radar stealth device

    NASA Astrophysics Data System (ADS)

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

    1991-07-01

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

  7. Dielectric Constant Modelling with Soil–Air Composition and Its Effect on Sar Radar Signal Backscattered over Soil Surface

    PubMed Central

    Zribi, Mehrez; Le Morvan, Aurélie; Baghdadi, Nicolas

    2008-01-01

    The objective of this paper is to present the contribution of a new dielectric constant characterisation for the modelling of radar backscattering behaviour. Our analysis is based on a large number of radar measurements acquired during different experimental campaigns (Orgeval'94, Pays de Caux'98, 99). We propose a dielectric constant model, based on the combination of contributions from both soil and air fractions. This modelling clearly reveals the joint influence of the air and soil phases, in backscattering measurements over rough surfaces with large clods. A relationship is established between the soil fraction and soil roughness, using the Integral Equation Model (IEM), fitted to real radar data. Finally, the influence of the air fraction on the linear relationship between moisture and the backscattered radar signal is discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  9. The detection of weak signal patterns in radar ocean intensity images

    SciTech Connect

    Manasse, R.

    1996-06-15

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

  10. UWB RADAR Receiver Architecture

    Microsoft Academic Search

    Nuno Paulino; Adolfo Steiger Garção; João Goes

    this chapter describes the operation of a radar system. The differences and advantages of using UWB signals in the radar system,\\u000a over traditional narrow band signals, are discussed. The radar equation, usually defined for narrow band signals, is redefined\\u000a for UWB signals. This new radar equation is used to analyze the echo signals from targets with basic shapes, resulting in

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  12. Active radar stealth device

    Microsoft Academic Search

    R. N. Cain; Albert J. Corda

    1991-01-01

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

  13. Fusion of multistatic synthetic aperture radar data to obtain a superresolution image

    Microsoft Academic Search

    Ali Mohammad-Djafari; Sha Zhu; Franck Daout; Philippe Fargette

    2010-01-01

    When using a single emitter and a single receiver, the Synthetic Aperture Radar (SAR) data gives information in the Fourier domain of the scene over a line segment whose width is related to the bandwidth of the emitted signal. The mathematical problem of image reconstruction in SAR then becomes a Fourier Synthesis (FS) inverse problem. When there are more than

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

    Microsoft Academic Search

    Lingyu Yu; Victor Giurgiutiu

    2005-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

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

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

    E-print Network

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

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

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

    USGS Publications Warehouse

    Wildey, R.L.

    1980-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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).

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

    NASA Technical Reports Server (NTRS)

    Lee, Jonggil

    1990-01-01

    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.

  20. Millimeter-wave circuits and pulse compression radar baseband/analog signal processing blocks in silicon processes

    E-print Network

    Parlak, Mehmet; Parlak, Mehmet

    2012-01-01

    pulse compression radar system for the pedes- trian detection sensor. . . . . . . . . . . . . . . . . . . . . . . . .cost pulse radar module for a pedestrian detection sensorpulse compression radar system for the pedestrian de- tection sensor.

  1. The modification of X and L band radar signals by monomolecular sea slicks

    NASA Astrophysics Data System (ADS)

    Hühnerfuss, Heinrich; Alpers, Werner; Cross, Aubrey; Garrett, William D.; Keller, William C.; Lange, Philipp A.; Plant, William J.; Schlude, Franz; Schuler, Dale L.

    1983-11-01

    One methyl oleate and two oleyl alcohol surface films were produced on the surface of the North Sea under comparable oceanographic and meteorological conditions in order to investigate their influence on X and L band radar backscatter. Signals are backscattered in these bands primarily by surface waves with lengths of about 2 and 12 cm, respectively, and backscattered power levels in both bands were reduced by the slicks. The reduction was larger at X band than at L band, however, indicating that shorter waves are more intensely damped by the surface films. The oleyl alcohol film caused greater attenuation of short gravity waves than the film of methyl oleate, thus demonstrating the importance of the physicochemical properties of films on the damping of wind-generated gravity capillary waves. Finally, these experiments indicate a distinct dependence of the degree of damping on the angle between wind and waves. Wind-generated waves traveling in the wind direction are more intensely damped by surface films than are waves traveling at larger angles to the wind.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

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

    Microsoft Academic Search

    Iwan Holleman; Asko Huuskoneny; Mikko Kurriy; Hans Beekhuis

    When operating a network of weather radars for monitoring of (severe) precipitation and (strong) wind, data quality and network homogeneity are of crucial importance. Using sun for offline calibration of the antenna alignment is a well- established method and tools for this are included in the software packages provided by the radar manufacturers. This offline calibration is typically performed during

  4. Least square spline decomposition in time-frequency analysis of weather radar signals

    Microsoft Academic Search

    K. I. Shelevytska; O. S. Semenova; I. V. Shelevytsky; F. J. Yanovsky

    2011-01-01

    Meteorology plays an important role in aviation, as it enables to predict weather conditions and detect flight dangerous meteorological phenomena. Meteorological radar is used to detect the intensity and possible location of precipitation and dangerous zones in them. Doppler radar systems are able to measure the speed of scatteres that constitute meteorological formations and phenomena. The tasks of measurement accuracy

  5. Predistortion Arithmetic on Low Sidelobe Pulse Compression Signal for Spaceborne Weather Radar

    Microsoft Academic Search

    Di Zhu; Xiaolong Dong

    2008-01-01

    Pulse compression with very low sidelobes is one of challenges in the design of spaceborne weather radar. To detect the weak echoes of clouds occurring near the strong echoes of sea surface, sidelobe performance below -60 db is needed in the pulse compression system. To achieve such low sidelobes, high SNR and linearity are required in the radar system. But

  6. Sensitivity of the radar signal to soil moisture: variation with incidence angle, frequency, and polarization

    Microsoft Academic Search

    I. Champion; R. Faivre

    1997-01-01

    This study focuses on the variations of the radar sensitivity to soil moisture (d?o\\/dmυ) with the radar configuration parameters (frequency, polarization, and angle). An analysis of variance shows that only the polarization significantly influences d?o\\/dmυ, which is larger at cross-polarization than at like-polarized configurations

  7. Coherent effects of moisture in backscattered radar signal from soil surfaces

    Microsoft Academic Search

    D. Despan; P. Borderies; J. P. Rudant

    2003-01-01

    Radar interferometry techniques are used in geodesy for investigating solid earth surface. The interferometric phase depends on topography but also on the moisture distribution at surface. Indoor experiments and theoretical modelling were used in order to study the effect of moisture on the radar phase response. A series of experiments have been performed at the European Microwave Signature Laboratory of

  8. Hail statistic in Western Europe based on a hyrid cell-tracking algorithm combining radar signals with hailstone observations

    NASA Astrophysics Data System (ADS)

    Fluck, Elody

    2015-04-01

    Hail statistic in Western Europe based on a hybrid cell-tracking algorithm combining radar signals with hailstone observations Elody Fluck¹, Michael Kunz¹ , Peter Geissbühler², Stefan P. Ritz² With hail damage estimated over Billions of Euros for a single event (e.g., hailstorm Andreas on 27/28 July 2013), hail constitute one of the major atmospheric risks in various parts of Europe. The project HAMLET (Hail Model for Europe) in cooperation with the insurance company Tokio Millennium Re aims at estimating hail probability, hail hazard and, combined with vulnerability, hail risk for several European countries (Germany, Switzerland, France, Netherlands, Austria, Belgium and Luxembourg). Hail signals are obtained from radar reflectivity since this proxy is available with a high temporal and spatial resolution using several hail proxies, especially radar data. The focus in the first step is on Germany and France for the periods 2005- 2013 and 1999 - 2013, respectively. In the next step, the methods will be transferred and extended to other regions. A cell-tracking algorithm TRACE2D was adjusted and applied to two dimensional radar reflectivity data from different radars operated by European weather services such as German weather service (DWD) and French weather service (Météo-France). Strong convective cells are detected by considering 3 connected pixels over 45 dBZ (Reflectivity Cores RCs) in a radar scan. Afterwards, the algorithm tries to find the same RCs in the next 5 minute radar scan and, thus, track the RCs centers over time and space. Additional information about hailstone diameters provided by ESWD (European Severe Weather Database) is used to determine hail intensity of the detected hail swaths. Maximum hailstone diameters are interpolated along and close to the individual hail tracks giving an estimation of mean diameters for the detected hail swaths. Furthermore, a stochastic event set is created by randomizing the parameters obtained from the tracking approach of the historical event catalogue (length, width, orientation, diameter). This stochastic event set will be used to quantify hail risk and to estimate probable maximum loss (e.g., PML200) for a given industry motor or property (building) portfolio.

  9. THE ElTECTS OF WIDE-BAND SIGNALS ON RADAR ANTENNA DESIGN Lawrence R. ~ a u ~ i n ,lht, USAF

    E-print Network

    Pratt, Vaughan

    THE ElTECTS OF WIDE-BAND SIGNALS ON RADAR ANTENNA DESIGN Lawrence R. ~ a u ~ i n ,lht, USAF Kenneth r wide-band signals by a simpler illuminationfunction. Some examples of the theory are given be reduced if s(t) i s a wide-band signal. Kock and Stone2havepointedout t h a t bycross- correlation

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

    NASA Astrophysics Data System (ADS)

    Mishra, Kumar Vijay

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

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

    Microsoft Academic Search

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

    1995-01-01

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

  12. Selective emitters

    NASA Astrophysics Data System (ADS)

    Chubb, Donald L.

    1992-01-01

    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.

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

    E-print Network

    Oppenheim, Meers

    -spread trail echoes. In this paper, we present analysis of nonspecular trails detected with ALTAIR, which. For ALTAIR, this means that the aspect angle must be within approximately 12 degrees in order to detect Research Projects Agency (ARPA) Long-Range Tracking and Instrumentation Radar (ALTAIR), measure short dura

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

    Microsoft Academic Search

    Werner Alpers; Klaus Hasselmann

    1982-01-01

    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

  15. Wavelet signal processing for radar target identification: a scale sequential approach

    Microsoft Academic Search

    Anthony J. Devaney; Bulent Hisconmez

    1994-01-01

    The problem of identifying a target from noisy high-range- resolution (HRR) data is addressed for the case of large radar target signature databases. The problem is treated using a general formulation of the problem of M-ary target identification in the presence of additive white Gaussian noise. A multiresolution analysis of the data and signature database relative to a discrete orthonormal

  16. A procedure for detecting the number of signal components in a radar measurement

    Microsoft Academic Search

    Pinyuen Chen; Michael C. Wicks

    2000-01-01

    This paper uses statistical selection theory to detect the multiplicity of the smallest eigenvalue of the covariance matrix, computed using measured multichannel multipulse radar data. We propose a selection procedure to estimate the multiplicity and value of the smallest eigenvalue(s). We derive the probability of a correct selection, P(CS), and the least favorable configuration (LFC) for our procedures. Under the

  17. A robust neural network based pulse radar detection for weak signals

    Microsoft Academic Search

    Aditya V. Padaki; Koshy George

    2010-01-01

    In this paper we develop a neural network capable of detecting targets with weak echoes in a pulse radar. This is possible as the network is designed as a pattern classifier (in contrast to earlier work) together with a suitable but simple pre-processing of the returns. We demonstrate through simulations that such a network exhibits better range resolution and noise

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

    USGS Publications Warehouse

    Wildey, R.L.

    1988-01-01

    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.

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

    E-print Network

    Préaux, Jean-Philippe

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

  20. IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 57, NO. 9, SEPTEMBER 2009 3533 MIMO Radar Waveform Optimization With Prior

    E-print Network

    Vaidyanathan, P. P.

    target in clutter. The MIMO radar systems can be classified into two cate- gories: 1) bistatic MIMO radar [27], and 2) colocated MIMO radar [28]. In the bistatic case, the transmitting antennas are widely the performance of detection [26] and angle estimation [25]. A tutorial on the bistatic MIMO radar can be found

  1. Ground-penetrating radar methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

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

    Microsoft Academic Search

    Eric Rignot; Keith Echelmeyer; William Krabill

    2001-01-01

    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, deltap. On cold polar firn

  3. Applications of (Wigner-Type) Time-Frequency Distributions to Sonar and Radar Signal Analysis

    Microsoft Academic Search

    Guillermo C. Gaunaurd; Hans C. Strifors

    2003-01-01

    Wigner-type distributions have shown their effectiveness in classification\\u000aproblems of sonar and radar. We present an overview of applications where\\u000aresonance features in echoes scattered from targets insonified or illuminated\\u000awith short pulses are studied in the joint time-frequency domain. We first show\\u000athe acoustic case of an elastic shell with a few filler materials submerged in\\u000awater and insonified

  4. Ground-penetrating radar signal processing for the detection of buried objects

    Microsoft Academic Search

    Mitchell Walters; Ephrahim Garcia

    2011-01-01

    In this work the singular value decomposition (SVD) is used to analyze matrices of ground penetrating radar (GPR) data. The targets to be detected are Russian PMN antipersonnel landmines and improvised explosive devices constructed from 155mm artillery shells. Target responses are simulated with GPRmax 2D, a simulation package based on the Finite- Difference-Time-Domain method. First, the utility of the SVD

  5. Detection and localization of multiple unresolved extended objects via monopulse radar signal processing

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Willett, Peter; Bar-Shalom, Yaakov

    2005-09-01

    With high resolution radars, realistic objects should be considered as extended rather than point targets. If several closely-spaced targets fall within the same radar beam and between adjacent matched filter samples in range, the full monopulse information from all of these samples can and should be used for estimation, both of angle and of range (with the range to sub-bin accuracy). To detect and localize multiple unresolved extended targets, we establish a model for monopulse radar returns from extended objects, and use a maximum likelihood estimator to localize the targets. Rissanen's minimum description length (MDL) will be used to decide the number of existing extended objects. We compare the new extended target monopulse processing scheme with previously developed point target monopulse techniques to show the improvement in terms of the estimation of target locations, the detection of the number of existing targets, and the tracking performance with a multiple hypothesis tracker (MHT) using the output from the proposed extended target monopulse processor.

  6. Beam emittance measurements in RHIC

    SciTech Connect

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

    2009-05-04

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  8. Multidimensional radar picture

    NASA Astrophysics Data System (ADS)

    Waz, Mariusz

    2010-05-01

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

  9. Nonintercepting emittance monitor

    SciTech Connect

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

    1983-08-01

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

  10. 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)

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

    2014-04-01

    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.

  11. Evaluating offshore wind energy resource by spaceborne radar sensors: the use of advanced signal processing techniques

    NASA Astrophysics Data System (ADS)

    Fichaux, Nicholas; Ranchin, Thierry

    2002-01-01

    In the framework of the current development of offshore wind energy exploitation, an accurate evaluation of the wind potential is crucial for sitting windmills. Nowadays, the resource is evaluated by intrusive means that provide discrete measurements. These measurements must be extrapolated in order to provide a global wind resource map. But in this case, local conditions and variations of wind are not expressed. This paper deals with a methodology developed to provide accurate offshore wind potential statistics. Firstly, the method developed to obtain accurate wind maps from ERS SAR (Synthetic Aperture Radar) images is presented. Then, considering the need of dense statistical information for evaluating the wind potential, a data fusion methodology is exposed.

  12. Wavelet signal processing for radar target identification: a scale sequential approach

    NASA Astrophysics Data System (ADS)

    Devaney, Anthony J.; Hisconmez, Bulent

    1994-03-01

    The problem of identifying a target from noisy high-range- resolution (HRR) data is addressed for the case of large radar target signature databases. The problem is treated using a general formulation of the problem of M-ary target identification in the presence of additive white Gaussian noise. A multiresolution analysis of the data and signature database relative to a discrete orthonormal wavelet basis is employed and shown to lead to a scale-sequential identification algorithm that has the property of making an identification having prespecified detection probabilities with the minimum number of computations. The general formulation is outlined and a computer-simulated example of target identification using the procedure is presented and discussed.

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

    SciTech Connect

    Middleton, D.

    1996-05-02

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

  14. Frequency Subband Processing and Feature Analysis of Forward-Looking Ground-Penetrating Radar Signals for LandMine Detection

    Microsoft Academic Search

    Tsaipei Wang; James M. Keller; Paul D. Gader; Ozy Sjahputera

    2007-01-01

    There has been significant amount of study on the use of ground-penetrating radar (GPR) for land-mine detection. This paper presents our analysis of GPR data collected at a U.S. Army test site using a new approach based on frequency subband processing. In this approach, from the radar data that have over 2.5 GHz of bandwidth, we compute separate radar images

  15. Microphysical cross validation of spaceborne radar and ground polarimetric radar

    Microsoft Academic Search

    V. Chandrasekar; Steven M. Bolen; Eugenio Gorgucci

    2003-01-01

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

  16. Target identification from radar signatures

    Microsoft Academic Search

    R. Strattan

    1978-01-01

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

  17. Analysis of weather radar return

    Microsoft Academic Search

    D. Payne

    1977-01-01

    A mathematical model of detected clutter from an airborne weather radar of conventional design is developed. The model is the joint probability density of samples of radar return from hydrometeors at the same nominal range and scan angle. It is developed from analysis of the effect on the received signal of the following parameters: inhomogeneous hydrometeor motion, radar frequency stability,

  18. Aberration Corrected Emittance Exchange

    E-print Network

    Nanni, Emilio A

    2015-01-01

    Full exploitation of emittance exchange (EEX) requires aberration-free performance of a complex imaging system including active radio-frequency (RF) elements which can add temporal distortions. We investigate the performance of an EEX line where the exchange occurs between two dimensions with normalized emittances which differ by orders of magnitude. The transverse emittance is exchanged into the longitudinal dimension using a double dog-leg emittance exchange setup with a 5 cell RF deflector cavity. Aberration correction is performed on the four most dominant aberrations. These include temporal aberrations that are corrected with higher order magnetic optical elements located where longitudinal and transverse emittance are coupled. We demonstrate aberration-free performance of emittances differing by 4 orders of magnitude, i.e. an initial transverse emittance of $\\epsilon_x=1$ pm-rad is exchanged with a longitudinal emittance of $\\epsilon_z=10$ nm-rad.

  19. Emittance Theory for Cylindrical Fiber Selective Emitter

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.

    1998-01-01

    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.

  20. Radar Detection using Sparsely Distributed Apertures in Urban Environment

    E-print Network

    Yazici, Birsen

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

  1. OFDM waveforms for multistatic radars

    Microsoft Academic Search

    Y. Paichard

    2010-01-01

    In this paper, the benefits of OFDM waveforms are analyzed for multistatic radar systems, where several radar stations cooperate in the same frequency band. The signal is coded over a 2D pattern, in the time and the frequency domains, using orthogonal Golay complementary sets derived from Reed-Muller codes. Binary data are also encoded in the signal. The obtained ambiguity and

  2. Classification algorithms for weather radar

    Microsoft Academic Search

    Felix Yanovsky; Vitaly Marchuk; Yaroslav Ostrovsky; Yulia Averyanova

    2008-01-01

    Theory, measurements, and signal processing applying to the radar remote sensing of weather objects are considered. Algorithms for hydrometeor type and turbulence intensity recognition are developed and analyzed. Particularly, fuzzy logic and neural network approaches are applied for weather radar signal processing.

  3. Radar Technology Applied to Air Traffic Control

    Microsoft Academic Search

    WILLIAM W. SHRADER

    1973-01-01

    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

  4. Noise modulated multistatic surveillance radar concept

    Microsoft Academic Search

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

    2006-01-01

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

  5. Spaceborne weather radar

    NASA Technical Reports Server (NTRS)

    Meneghini, Robert; Kozu, Toshiaki

    1990-01-01

    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.

  6. Micropower impulse radar imaging

    SciTech Connect

    Hall, M.S.

    1995-11-01

    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.

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

    PubMed Central

    Wang, Yong

    2015-01-01

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

  8. Obstacle penetrating dynamic radar imaging system

    DOEpatents

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

    2006-12-12

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

  9. AN EMITTANCE EVALUATION TOOLBOX

    Microsoft Academic Search

    D. Liakin; P. Forck; T. Hoffmann

    A long-time experience in emittance measurements and result evaluation at GSI were transformed into a set of numerical instruments to perform basic and advanced data analysis for data obtained in various emittance measurement systems. The common problems and differences between slit-grid-, pepper-pot- and longitudinal emittance data analysis are discussed. Some aspects of non-linear algorithms particularly for the case of non-zero

  10. Ultra wideband multiple-input multiple-output radar

    Microsoft Academic Search

    Hammad A. Khan; Wasim Q. Malik; David J. Edwards; Christopher J. Stevens

    2005-01-01

    The utilization of ultra wideband (UWB) signals enables the radar designer to solve the most important problems of radar target observation. The extremely wide bandwidth enables greater information to be obtained due to high time resolution and the frequency dependence of the scattering centers over this large bandwidth. Increase in the radar's signal bandwidth can improve radar performance by providing

  11. Terminal Doppler weather radar

    Microsoft Academic Search

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

    1990-01-01

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

  12. Abstract--Ionospheric contributions to the phase of L-band2 Synthetic Aperture Radar (SAR) signals put severe3

    E-print Network

    Paris-Sud XI, Université de

    1 1 Abstract-- Ionospheric contributions to the phase of L-band2 Synthetic Aperture Radar (SAR ionospheric contributions to surface displacement11 measurements derived from L-band SAR data. We test the12 displacement, which has important implications in17 earthquake modelling based on L-band SAR data.18 19 Index

  13. HRR profile imaging of fast moving target based on multiple radars using wide-band LFM signals

    Microsoft Academic Search

    Fulai Liang; Xiaotao Huang; Xiangyang Li; Qian Song

    2008-01-01

    It is efficient to enlarge the radar bandwidth based on multi-band fusion. However, the former research on multi-band fusion did not take velocity into consideration. When the velocity is very high or pulse width is long, ignoring the impact of high speed the range resolution will deteriorate heavily. In this paper the authors develop a new method of forming high

  14. Diamond fiber field emitters

    DOEpatents

    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

    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.

  15. On pecularities of the magnitospheric disturbances accompanied by signals of mid-latitude coherent echo based on Irkutsk Incoherent Scatter radar data.

    NASA Astrophysics Data System (ADS)

    Zolotukhina, N. A.; Berngardt, O. I.; Shpynev, B. G.

    The aim of the paper is the investigation of auroral echo peculiarities observed at mid-latitudes with corrected geomagnetic latitudes 52-58 grad based on the Irkutsk Incoherent Scatter radar IISR data In the paper the dependence of observation frequency duration and power of the scattered signal on time and on circular current intensity are investigated as well as magnitospheric causes leading to the coherent echo observed at mid-latitudes An algorithm for detecting existence of the coherent echo from power profile of scattered signal is presented The analysis of mid-latitude coherent echo observed by IISR during January 1998 - January 2005 period is carried out Echo signals which were revealed during the analysis were divided into 2 groups by intensity strong s and weak w ones A numerical characteristic that defines fragmentariness level of the coherent echo over the time is suggested It allows us to divide the observed echo into prolonged and fragmentary ones The analysis of data which is obtained at the Irkutsk Incoherent Scatter radar over the 7 years and is presented in the given paper shows the following 1 The signals defined in this paper as a weak auroral echo are observed at mid-latitudes at any geomagnetic activity level at any local time It is not improbable however that a part of the events is associated with the given group erroneously so their nature requires further detailed investigation 2 The probability of the strong auroral echo occurrence at middle latitudes is maximal from midnight till morning and is minimal at

  16. Pulsed hybrid field emitter

    DOEpatents

    Sampayan, Stephen E. (Manteca, CA)

    1998-01-01

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

  17. Pulsed hybrid field emitter

    DOEpatents

    Sampayan, S.E.

    1998-03-03

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

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

    Microsoft Academic Search

    K. Rosenbach; J. Schiller

    2000-01-01

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

  19. A Sparse Signal Representation-based Approach to Image Formation and Anisotropy Determination in Wide-Angle Radar

    Microsoft Academic Search

    K. R. Varshney; M. Cetin; J. W. Fisher; A. S. Willsky

    2007-01-01

    We consider the problem of jointly forming images and determining anisotropy from wide-angle synthetic aperture radar (SAR) measurements. Conventional SAR image formation techniques assume isotropic scattering, which is not valid with wide-angle apertures. We present a method based on a sparse representation of aspect-dependent scattering with an overcomplete dictionary composed of elements with varying levels of angular persistence. Solved as

  20. Emittance studies with an Allison scanner

    SciTech Connect

    Stockli, M.P.; Welton, R.F.; Keller, R.; Leitner, M. [SNS, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831 (United States); Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)

    2006-03-15

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

  1. Radar Entomology

    NSDL National Science Digital Library

    0000-00-00

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

  2. Radar principles

    NASA Technical Reports Server (NTRS)

    Sato, Toru

    1989-01-01

    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.

  3. Imaging Radar for Ecosystem Studies

    NASA Technical Reports Server (NTRS)

    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

    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.

  4. Frequency diversity in multistatic radars

    Microsoft Academic Search

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

    2008-01-01

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

  5. Portable emittance measurement device

    SciTech Connect

    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

    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.

  6. Portable emittance measurement devicea)

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

    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.

  7. Portable emittance measurement device.

    PubMed

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

    2010-02-01

    In Institute for Theoretical and Experimental Physics (ITEP) the portable emittance measurements device is developed. It provides emittance measurements both with "pepper-pot" and "two slits" methods. Depending on the method of measurements, either slits or pepper-pot mask with scintillator are mounted on the two activators and are installed in two standard Balzer's cross chamber with CF-100 flanges. To match the angle resolution for measured beam, the length of the stainless steel pipe between two crosses changes is adjusted. The description of the device and results of emittance measurements at the ITEP ion source test bench are presented. PMID:20192459

  8. Laser Assisted Emittance Exchange

    SciTech Connect

    Xiang, Dao; /SLAC

    2012-06-11

    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.

  9. PM and AM noise of BJT amplifiers with quartz crystal resonator in emitter circuit

    Microsoft Academic Search

    T. I. Boldyreva

    1999-01-01

    An algorithm of bipolar junction transistor (BJT) amplifier PM and AM noise calculation, described in (1998), is applied to BJT amplifiers, having common emitter (CE) and common emitter-common base (CE-CB) circuit configurations with quartz crystal resonator (QR) inserted in emitter circuits. Power spectral densities (PSD) of PM and AM noise introduced by these amplifiers when signal frequency is close to

  10. Portable emittance measurement device

    Microsoft Academic Search

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

    2010-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  12. Radar reflection off extensive air showers

    E-print Network

    Stasielak, J; Bertaina, M; Blümer, J; Chiavassa, A; Engel, R; Haungs, A; Huege, T; Kampert, K -H; Klages, H; Kleifges, M; Krömer, O; Ludwig, M; Mathys, S; Neunteufel, P; Pekala, J; Rautenberg, J; Riegel, M; Roth, M; Salamida, F; Schieler, H; Šmída, R; Unger, M; Weber, M; Werner, F; Wilczy?ski, H; Wochele, J

    2012-01-01

    We investigate the possibility of detecting extensive air showers by the radar technique. Considering a bistatic radar system and different shower geometries, we simulate reflection of radio waves off the static plasma produced by the shower in the air. Using the Thomson cross-section for radio wave reflection, we obtain the time evolution of the signal received by the antennas. The frequency upshift of the radar echo and the power received are studied to verify the feasibility of the radar detection technique.

  13. When Target Motion Matters: Doppler Coverage in Radar Sensor Networks

    E-print Network

    Reisslein, Martin

    that are not of interest as well as objects of interest (e.g., targets). The detection performance of radar systems-covered if, regardless of its direction of motion, there exists some radar in the network whose signal- to for arbitrarily deployed radars. Then we design an algorithm for deriving the minimum radar density required

  14. Robust Sparse Sensing Using Weather Radar

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    The ability of a weather radar to detect weak echoes is limited by the presence of noise or unwanted echoes. Some of these unwanted signals originate externally to the radar system, such as cosmic noise, radome reflections, interference from co-located radars, and power transmission lines. The internal source of noise in microwave radar receiver is mainly thermal. The thermal noise from various microwave devices in the radar receiver tends to lower the signal-to-noise ratio, thereby masking the weaker signals. Recently, the compressed sensing (CS) technique has emerged as a novel signal sampling paradigm that allows perfect reconstruction of signals sampled at frequencies lower than the Nyquist rate. Many radar and remote sensing applications require efficient and rapid data acquisition. The application of CS to weather radars may allow for faster target update rates without compromising the accuracy of target information. In our previous work, we demonstrated recovery of an entire precipitation scene from its compressed-sensed version by using the matrix completion approach. In this study, we characterize the performance of such a CS-based weather radar in the presence of additive noise. We use a signal model where the precipitation signals form a low-rank matrix that is corrupted with (bounded) noise. Using recent advances in algorithms for matrix completion from few noisy observations, we reconstruct the precipitation scene with reasonable accuracy. We test and demonstrate our approach using the data collected by Iowa X-band Polarimetric (XPOL) weather radars.

  15. International Radar Conference, Arlington, VA, May 6-9, 1985, Record and Supplement

    NASA Astrophysics Data System (ADS)

    1985-12-01

    The topics discussed in this volume include advanced antennas and transmitters, targets and environments, signal processing, specialized radars adn techniques, synthetic aperture radar, and radar automation, as well as some novel radar system designs. Papers are presented on an efficient three-dimensional radar design, monitoring and calibration of active phased arrays, the solid state transmitter for the AN/SPS-40 radar system, and the superresolution application in tracking radar. Consideration is given to Doppler estimation accuracy of linear FM waveforms, a bistatic pulse-Doppler intruder detection radar, detectability of low flying targets in real terrain using a diffraction model, a technique for adaptive polarization filtering in radars, and the effects of polarization on the marine radar detection of icebergs. In addition, strategies for radar frequency selection, low probability of intercept radar, synthetic aperture imaging airborne radar, and optical techniques for signal distribution and control in phased array radars are discussed.

  16. Emittance Degradation Measurements

    NASA Astrophysics Data System (ADS)

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

    1997-05-01

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

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

    Microsoft Academic Search

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

    2005-01-01

    ** , 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), \\

  18. P15R.1 THE DETECTABILITY OF TORNADIC SIGNATURES WITH DOPPLER RADAR: A RADAR EMULATOR STUDY

    E-print Network

    Xue, Ming

    , and the minimum detectable signal. The parameters that describe the scanning strategy are: pulse repetition timeP15R.1 THE DETECTABILITY OF TORNADIC SIGNATURES WITH DOPPLER RADAR: A RADAR EMULATOR STUDY Ryan M. The application of this emulator to studying the detectability of tornadoes by broad-beam, low power radars

  19. Electrochemical formation of field emitters

    DOEpatents

    Bernhardt, Anthony F. (Berkeley, CA)

    1999-01-01

    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.

  20. Environmental awareness for sensor and emitter employment

    NASA Astrophysics Data System (ADS)

    Yamamoto, Kenneth K.; Wilson, D. Keith

    2010-04-01

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

  1. Bistatic radar meteorological satellite

    NASA Technical Reports Server (NTRS)

    Nathanson, F. E.

    1981-01-01

    A technique is discussed that employs a radar transmitter with a moderate size antenna placed in a geosynchronous orbit with either a 0 degree or a low inclination orbit. The reflected signals from the precipitation are then received either on a single beam from a satellite having a beamwidth of about 6 degrees or preferably with a beam that scans the U.S. in a raster pattern with about 0.9 degrees beamwidth. While it would seem that a bistatic system with the transmitter at synchronous altitude and the receivers near the surface would not be a very efficient way of designing a radar system, it is somewhat surprising that the required power and antenna sizes are not that great. Two factors make the meteorological application somewhat more attractive than the bistatic detection of point targets. First, the bistatic reflections of radar signals from precipitation are to a large extent omnidirectional, and while raindrops are spheriods rather than spheres, the relationship of the reflectivity of the rain to rainfall rate can be easily derived. The second reason is that the rain echo signal level is independent of range from a receive only radar, and if the bistatic system works at all, it will work at long ranges.

  2. Target localization by a multistatic UWB radar

    Microsoft Academic Search

    M. S?vecova?; D. Kocur; R. Zetik; J. Rovn?a?kova?

    2010-01-01

    Moving target localization and tracking are of great interest for rescue, surveillance and security operations. The radar signal processing procedure providing the target position estimation consists of such phases of signal processing as raw radar data pre-processing, background subtraction, detection, time of arrival estimation, localization and tracking. In this paper, we will focus on the localization phase where we assume

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

    NASA Technical Reports Server (NTRS)

    Fukao, Shoichiro (editor)

    1989-01-01

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

  4. Spaceborne radar

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  5. FACET Emittance Growth

    SciTech Connect

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

    2011-04-05

    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.

  6. Space-based radar handbook

    NASA Astrophysics Data System (ADS)

    Cantafio, Leopold J.

    The design and operation of space-based radar (SBR) systems are discussed in chapters contributed by leading experts. An overview of current and planned SBRs is presented, and particular attention is given to SBR-platform orbits, the ionospheric environment and its effects on SBR detection, space-based SARs, bistatic SBRs, rendezvous radars, radar altimeters for space vehicles, scatterometers and other modest-resolution systems, and thermal control for SBRs. Also considered are the radar cross sections of satellites and other space targets, SBR clutter and interference, space antenna technology, onboard radar-signal processors, space power systems, and SBR structures. Diagrams, drawings, graphs, maps, and tables of numerical data are provided.

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

    PubMed

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

    2015-02-01

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

  8. Imaging synthetic aperture radar

    DOEpatents

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

    1997-01-01

    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.

  9. Tracking system for photon-counting laser radar

    E-print Network

    Chang, Joshua TsuKang

    2007-01-01

    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 ...

  10. 3152 IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 58, NO. 6, JUNE 2010 OFDM MIMO Radar With Mutual-Information

    E-print Network

    Nehorai, Arye

    , such as Earth's curvature, vertical refractivity gradient of lower at- mosphere, and compound amenable to signal processing. In this work, we consider the effects of the Earth's curvature and linear of the Earth's at- mosphere), the Earth's curved surface, the roughness of the sea surface, etc. Therefore

  11. Rare earth garnet selective emitter

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  12. Monolithic multinozzle emitters for nanoelectrospray mass spectrometry

    DOEpatents

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

    2011-09-20

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

  13. MIMO Radar Waveform Constraints for GMTI

    Microsoft Academic Search

    K. W. Forsythe; D. W. Bliss

    2010-01-01

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

  14. Radar volcano monitoring system in Iceland

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  15. Electrochemical formation of field emitters

    DOEpatents

    Bernhardt, A.F.

    1999-03-16

    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.

  16. Composite emitters for TPV systems

    SciTech Connect

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

    1995-01-05

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

  17. Large phased-array radars

    SciTech Connect

    Brookner, D.E.

    1988-12-15

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

  18. Large phased-array radars

    NASA Astrophysics Data System (ADS)

    Brookner, Eli, Dr.

    1988-12-01

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

  19. Development and characterization analysis of a radar polarimeter 

    E-print Network

    Bong, Soei Siang

    1984-01-01

    Measurement of the Minimum Detectable Signal and the Typical Power Output . . 83 14 Radar Cross Section Calculation for the Three Different Radar Frequencies Based Upon a Constant Return Power . . 85 15 Summary of the Component Parameters for the Power... minimum detectable signal can be calculated. The minimum defectable signal and the radar cross section of a target are statistical in nature. There is no statistical expression in equation (4b) to describe the statistical nature of the minimum 50...

  20. Autonomous Land Vehicle Navigation Using Millimeter Wave Radar

    Microsoft Academic Search

    Steve Clark; Hugh F. Durrant-whyte

    1998-01-01

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

  1. Frequency band selection of radars for buried object detection

    Microsoft Academic Search

    Mikhail Cherniakov; Lidia Donskoi

    1999-01-01

    Choice of the operational frequency is one of the most responsible parts of any radar design process. Parameters of radars for buried object detection (BOD) are very sensitive to both carrier frequency and ranging signal bandwidth. Such radars have a specific propagation environment with a strong frequency-dependent attenuation and, as a result, short operational range. This fact dictates some features

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

    E-print Network

    Baudoin, Geneviève

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

  3. 33 CFR 118.120 - Radar reflectors and racons.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

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

  4. 33 CFR 118.120 - Radar reflectors and racons.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  5. Classification of radar clutter in an air traffic control environment

    Microsoft Academic Search

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

    1991-01-01

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

  6. Twin VHF radar for european space situation awareness system

    Microsoft Academic Search

    Istvan Balajti

    2012-01-01

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

  7. Surveillance radars - State of the art, research and perspectives

    NASA Astrophysics Data System (ADS)

    Farina, A.; Galati, G.

    1985-08-01

    An assessment is made of the signal processing techniques currently employed by ground-based surveillance radars, and a projection is made of those techniques that are likely to be applied to such radars in the future. Further applications of such techniques in such diverse fields as multistatic and dispersed radars, AEW, and space-based radars are also considered. Attention is given to prospective technological advancements that will facilitate radar systems' future dealings with antiradiation missiles and stealth aircraft, which may include digital beam forming, adaptivity, and high resolution multidimensional processing and target classification. The advantages of multistatic radar are examined in detail.

  8. MUON COOLING - EMITTANCE EXCHANGE.

    SciTech Connect

    PARSA,Z.

    2001-02-16

    Muon Cooling is the key factor in building of a Muon collider, (to a less degree) Muon storage ring, and a Neutrino Factory. Muon colliders potential to provide a probe for fundamental particle physics is very interesting, but may take a considerable time to realize, as much more work and study is needed. Utilizing high intensity Muon sources - Neutrino Factories, and other intermediate steps are very important and will greatly expand our abilities and confidence in the credibility of high energy muon colliders. To obtain the needed collider luminosity, the phase-space volume must be greatly reduced within the muon life time. The Ionization cooling is the preferred method used to compress the phase space and reduce the emittance to obtain high luminosity muon beams. We note that, the ionization losses results not only in damping, but also heating. The use of alternating solenoid lattices has been proposed, where the emittance are large. We present an overview of the cooling and discuss formalism, solenoid magnets and some beam dynamics.

  9. Radar echo signatures versus relative precipitation 

    E-print Network

    Huber, Terry Alvin

    1987-01-01

    the evolutionary processes of and within the cell. Radar is well suited for this purpose. Once hydrometeors within the cloud attain minimum detectable size, the cloud's evolution may be tracked using radar. The lifecycle of cell echoes, from initial detection... of the detected signal by the earth's surface). A radar which has been correctly calibrated can produce rainfa'll estimates that are very reasonable. But, depending on the specific application and location of the radar, an elevation-scan angle between 28 0...

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

    Microsoft Academic Search

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

    2003-01-01

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

  11. Influence of radar frequency on the relationship between bare surface soil moisture vertical profile and radar backscatter

    E-print Network

    Paris-Sud XI, Université de

    Influence of radar frequency on the relationship between bare surface soil moisture vertical on the relationship between surface soil moisture and the nature of radar backscatter over bare soils. In an attempt the operational use of radar signals for the estimation of soil moisture. In this context, when the soil moisture

  12. Emitter bypassing in transistor circuits

    Microsoft Academic Search

    R. Murray

    1957-01-01

    The emitter bypass capacitor has probably become as commonplace in transistor circuitry as its vacuum tube counterpart, the cathode bypass capacitor. An equivalent circuit analysis of the common-emitter amplifier yields a simple relation that may be used for the determination of the approximate value of the capacitor in terms of the required low-frequency response and the circuit and transistor parameters.

  13. EMITTANCE COMPENSATION FOR MAGNETIZED BEAMS

    SciTech Connect

    KEWISCH,J.; CHANG, X.

    2007-06-25

    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.

  14. A satellite-based radar wind sensor

    NASA Technical Reports Server (NTRS)

    Xin, Weizhuang

    1991-01-01

    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.

  15. Advanced Borehole Radar for Hydrogeology

    NASA Astrophysics Data System (ADS)

    Sato, M.

    2014-12-01

    Ground Penetrating Radar is a useful tool for monitoring the hydrogeological environment. We have developed GPR systems which can be applied to these purposes, and we will demonstrate examples borehole radar measurements. In order to have longer radar detection range, frequency lower than100MHz has been normally adopted in borehole radar. Typical subsurface fractures of our interests have a few mm aperture and radar resolution is much poorer than a few cm in this frequency range. We are proposing and demonstrating to use radar polarimetry to solve this problem. We have demonstrated that a full-polarimetry borehole radar can be used for characterization of subsurface fractures. Together with signal processing for antenna characteristic compensation to equalize the signal by a dipole antenna and slot antennas, we could demonstrate that polarimetric borehole radar can estimate the surface roughness of subsurface fractures, We believe the surface roughness is closely related to water permeability through the fractures. We then developed a directional borehole radar, which uses optical field sensor. A dipole antenna in a borehole has omni-directional radiation pattern, and we cannot get azimuthal information about the scatterers. We use multiple dipole antennas set around the borehole axis, and from the phase differences, we can estimate the 3-diemnational orientation of subsurface structures. We are using optical electric field sensor for receiver of borehole radar. This is a passive sensor and connected only with optical fibers and does not require any electric power supply to operate the receiver. It has two major advantages; the first one is that the receiver can be electrically isolated from other parts, and wave coupling to a logging cable is avoided. Then, secondary, it can operate for a long time, because it does not require battery installed inside the system. It makes it possible to set sensors in fixed positions to monitor the change of environmental conditions for a long period. We demonstrated this idea using cross- hole borehole radar measurement. We think this method is useful for detecting any changes in hydrogeological situations, which will be useful for subsurface storage such as LNG and nuclear waste.

  16. Fly eye radar or micro-radar sensor technology

    NASA Astrophysics Data System (ADS)

    Molchanov, Pavlo; Asmolova, Olga

    2014-05-01

    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.

  17. Securing radars using secure wireless sensor networking

    NASA Astrophysics Data System (ADS)

    Tahmoush, David

    2014-06-01

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

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

    Microsoft Academic Search

    Aditya Prabaswara; Achmad Munir; Andriyan Bayu Suksmono

    2011-01-01

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

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

    E-print Network

    Elsherbeni, Atef Z.

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

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

    Microsoft Academic Search

    Zong-Guo Xia; Floyd M. Henderson

    1997-01-01

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

  1. Performance Analysis of Pulse Doppler Digital Radars with Application to the Shuttle Ku-Band System

    Microsoft Academic Search

    W. K. Alem; C. L. Weber

    1978-01-01

    The performance of a class of pulse Doppler radars with a digitally implemented signal processing unit is investigated. TheKuband rendezvous radar onboard the Shuttle Orbiter is a pulse Doppler radar which is in this class. The detection capability is first presented. A unified analysis of digital radar tracking loops is presented which employs logarithmic discriminants. The results are applied to

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

    Microsoft Academic Search

    R. J. Riddolls

    2007-01-01

    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

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

    Microsoft Academic Search

    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

    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

  4. Data compression in emitter location systems via sensor pairing and selection

    E-print Network

    Fowler, Mark

    of limited network communication resources. The sensors simultaneously intercept an RF emitter's signal data then uses knowledge of the current positions and trajectories of the remaining sensors to further reduceData compression in emitter location systems via sensor pairing and selection Xi Hu and Mark L

  5. RADAR PRINCIPLES I Introduction

    E-print Network

    Sato, Toru

    ) bands. Antenna size of weather radarsis a few to about ten metersin diameter, but an} atmospheric radar atmospheric radars have antennas witli dialneter of 10- 300 in. Weather radars cover a wide horizontal areaRADAR PRINCIPLES I Introduction Radar is a general technique, willcli has a wide range

  6. Limitations of Radar Coordinates

    E-print Network

    Donato Bini; Luca Lusanna; Bahram Mashhoon

    2004-12-17

    The construction of a radar coordinate system about the world line of an observer is discussed. Radar coordinates for a hyperbolic observer as well as a uniformly rotating observer are described in detail. The utility of the notion of radar distance and the admissibility of radar coordinates are investigated. Our results provide a critical assessment of the physical significance of radar coordinates.

  7. Accidental radio jamming suppression in passive radar

    Microsoft Academic Search

    Heng Zheng; Hongli Zhao; Fei Li

    2008-01-01

    Bistatic passive radar based on opportunity illuminators such as FM radio, is a hotspot in the domain of radar. The direct\\/multi-path signals cancellation techniques(DSC) have been discussed by many scholars. These considered algorithms adopt a single-stage adaptive filter processor frame, have sufficient performance in the cancellation of the direct\\/multi-path interference signals from the selected transmitter. In practice, because of the

  8. Wideband OFDM system for radar and communications

    Microsoft Academic Search

    Dmitriy Garmatyuk; Jonathan Schuerger; Kyle Kauffman; Scott Spalding

    2009-01-01

    This paper describes the design and architectural composition of a radar system built on OFDM platform. The radar signal is generated digitally by forming an arbitrary-length vector of OFDM sub-carrier amplitudes and translating it in analog format via 1000 Ms\\/s D\\/A conversion. The resultant baseband signal has a bandwidth of 500 MHz, and variable number and composition of sub-carriers, which

  9. Signal processing for automotive radar

    Microsoft Academic Search

    Desmond Kok; Jeffrey S. Fu

    2005-01-01

    With rising accident rates, researchers are looking for solutions to reduce fatalities. Some enhance car designs to protect drivers more adequately. Some propose improvements to the traffic and road systems to reduce the chances of accidents. Still others propose the installation of special gadgets to improve the situational awareness of drivers and to alert them to dangerous circumstances. A motor

  10. CFAR detection for multistatic radar

    Microsoft Academic Search

    Vahideh Amanipour; Ali Olfat

    2011-01-01

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

  11. Test equipment for coherent radar

    Microsoft Academic Search

    D. B. Leeson; W. K. Saunders

    1974-01-01

    Test equipment for pulsed Doppler and CW coherent radar is described. Equipment developed for testing the Vulcan tracking system is discussed, and the test procedure is outlined. The Vulcan equipment provides measurements of STAMO quality, the additive noise contributed by the sideband modulator and klystron amplifier, limitations on subclutter visibility and the minimum detected signal in the receiving chain, lock

  12. TRMM radar

    NASA Technical Reports Server (NTRS)

    Okamoto, Kenichi

    1993-01-01

    The results of a conceptual design study and the performance of key components of the Bread Board Model (BBM) of the Tropical Rainfall Measuring Mission (TRMM) radar are presented. The radar, which operates at 13.8 GHz and is designed to meet TRMM mission objectives, has a minimum measurable rain rate of 0.5 mm/h with a range resolution of 250 m, a horizontal resolution of about 4 km, and a swath width of 220 km. A 128-element active phased array system is adopted to achieve contiguous scanning within the swath. The basic characteristics of BBM were confirmed by experiments. The development of EM started with the cooperation of NASDA and CRL.

  13. Porous Ion Emitters: A New Type of Thermal Ion Emitter

    SciTech Connect

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

    2010-10-01

    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.

  14. Measuring coal deposits by radar

    NASA Technical Reports Server (NTRS)

    Barr, T. A.

    1980-01-01

    Front-surface, local-oscillator radar directly compares frequency of signals reflected from front and back surfaces of coal deposits. Thickness is measured directly as frequency difference. Transmitter is frequency modulated, so thickness is computed directly from frequency difference. Because front and back reflections are detected in combination rather than separately, masking of comparatively weak back signal is less problem. Also system is not sensitive to extraneous reflections from targets between transmitting antenna and coal surface.

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

    E-print Network

    Paris-Sud XI, Université de

    scatter radars measure ionosphere parameters using modi®ed Thomson scatter from free electrons words: Radio science (ionospheric physics; signal processing; instruments and techniques) 1 Introduction Incoherent scatter radars have been designed to study the Earth's ionosphere in the altitude range from some

  16. Variability of Decimetre and Centimetre Scale Ice Surface Roughness and the Potential Consequences on the CryoSat Radar Altimeter Signal

    Microsoft Academic Search

    F. G. Cawkwell; D. O. Burgess; M. J. Sharp; M. Demuth

    2004-01-01

    Snow and ice surface roughness affect the backscatter of the pulse emitted by a radar altimeter, and hence the accuracy of the surface elevation calculated from the waveform echo, but the influence of surface roughness has not been quantified. As part of the CryoSat calibration\\/validation field campaigns on the Devon Ice Cap in 2004, surface roughness measurements were made at

  17. Radar waveform synthesis for target identification

    NASA Astrophysics Data System (ADS)

    Chen, K. M.

    1981-06-01

    A new scheme for radar detection and discrimination, the radar waveform synthesis method, is investigated. This scheme consists of synthesizing an aspect-independent waveform for the incident radar signal which excites an arbitrarily oriented target in such a way that the return radar signal from the target contains only a single natural resonance mode of the target in the late-time period. When the synthesized incident radar signal for exciting a particular natural mode of a known, preselected target is applied to a wrong target, the return radar signal will be significantly different from that of the expected natural mode, thus, the wrong target can be sensitively discriminated. The selection of an optimum pulse duration of the required incident signal for the purpose of shaping its waveform is also studied. Three kinds of targets, an arbitrarily oriented thin wire, a sphere and a normally oriented infinite cylinder, have been investigated. The cases of an arbitrarily oriented wire and a sphere have been completed and the results are reported in Parts 1 and 2. The case of infinite cylinder will be completed shortly and incomplete results of this case are outlined in Part 3.

  18. FPGA based Architecture for Radar's STC, FTC and Gain modules

    Microsoft Academic Search

    Joaquín García; Gilberto Viveros; René Cumplido

    Recent innovations like reconfigurable computing have allowed to easy experiment new architectures that support a wide range of applications for Digital Signal Processing (DSP). Field Programmable Gate Array (FPGA) provides a cheap platform for research and development. Radar signal processing is widely used for civil and military proposes. Radar's systems operate on Real-Time basis. This paper presents an architecture that

  19. A continuous-wave (CW) radar for gait analysis

    Microsoft Academic Search

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

    2001-01-01

    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

  20. COHPROC, a coherent processing algorithm for the Chilbolton radars

    E-print Network

    Hogan, Robin

    will be surrounded by signal-free pixels in the full radar image, so can be rejected on that basis. The minimum-detectable in N are reduced, which in turn enables the threshold to be lowered and smaller signals to be detectedCOHPROC, a coherent processing algorithm for the Chilbolton radars Robin Hogan Version 1.1, 7

  1. COHPROC, a coherent processing algorithm for the Chilbolton radars

    E-print Network

    Hogan, Robin

    will be surrounded by signal­free pixels in the full radar image, so can be rejected on that basis. The minimum­detectable in N are reduced, which in turn enables the threshold to be lowered and smaller signals to be detectedCOHPROC, a coherent processing algorithm for the Chilbolton radars Robin Hogan Version 1.1, 7

  2. Visible Spectrum Incandescent Selective Emitter

    SciTech Connect

    Sonsight Inc.

    2004-04-30

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

  3. Radar: The Cassini Titan Radar Mapper

    Microsoft Academic Search

    C. Elachi; M. D. Allison; L. Borgarelli; P. Encrenaz; E. Im; M. A. Janssen; W. T. K. Johnson; R. L. Kirk; R. D. Lorenz; J. I. Lunine; D. O. Muhleman; S. J. Ostro; G. Picardi; F. Posa; C. G. Rapley; L. E. Roth; R. Seu; L. A. Soderblom; S. Vetrella; S. D. Wall; C. A. Wood; H. A. Zebker

    2004-01-01

    The Cassini RADAR instrument is a multimode 13.8 GHz multiple-beam sensor that can operate as a synthetic-aperture radar (SAR) imager, altimeter, scatterometer, and radiometer. The principal objective of the RADAR is to map the surface of Titan. This will be done in the imaging, scatterometer, and radiometer modes. The RADAR altimeter data will provide information on relative elevations in selected

  4. Surface remote sensing applications of GNSS bistatic radar: Soil moisture and aircraft altimetry

    Microsoft Academic Search

    D. S. Masters

    2004-01-01

    In recent years, global navigation satellite system (GNSS) signals have been studied as opportunistic bistatic radar transmissions. Most of the previous work has concentrated on bistatic radar using Global Positioning System (CPS) signals to remotely sense Earth surface characteristics, such as ocean surface roughness and heights. This dissertation extends this field and investigates remote sensing using GNSS bistatic radar as

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

    E-print Network

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

  6. Sub-array level simulation of an active electronically scanned array radar for integrated system design

    Microsoft Academic Search

    N. W. Ramsey; C. McComb; D. W. Greig

    2002-01-01

    An overview of a complete simulation of an active electronically scanned array (AESA) radar system is given. The Airborne Radar Environment Simulation (ARES) tool has been developed to represent signals emanating from the radar's environment at the sub-array level. This data forms the input to a test bed simulation in which signal processing algorithms can be developed, in particular adaptive

  7. Measuring Antenna Patterns for Ocean Surface Current HF Radars with Ships of Opportunity

    E-print Network

    California at Santa Barbara, University of

    Measuring Antenna Patterns for Ocean Surface Current HF Radars with Ships of Opportunity BRIAN M-finding HF radars from ships of opportunity. Positions obtained from the Automatic Identification System (AIS) are used to identify signals backscattered from ships in ocean current radar data. These signals and ship

  8. Output resistance of the common-emitter amplifier

    Microsoft Academic Search

    D. L. Rode

    2005-01-01

    Contrary to a long-held belief, the output resistance of the common-emitter (CE) amplifier is not independent of its signal-source resistance. Although it is widely accepted that the output resistance of the CE amplifier is approximately equal to the ratio of the Early voltage to the collector current VA\\/IC, independent of the resistance of the signal source, it is shown herein

  9. Future Trends in Automotive Radar \\/ Imaging Radar

    Microsoft Academic Search

    J. Wenger

    1998-01-01

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

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

    SciTech Connect

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

    1995-01-23

    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.

  11. Principles of weather radar network design at attenuating frequencies

    NASA Astrophysics Data System (ADS)

    Junyent, F.; Lim, S.; Chandrasekar, V.

    2009-09-01

    The Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) is investigating the use of dense networks of short-range radars for weather sensing. A first test-bed of this new paradigm is currently deployed in southwest Oklahoma. The potential benefits of closely deployed, overlapping, short-range weather radars are easy to see intuitively, amounting to a greater ability to measure at lower beam heights, mitigating the effects of the Earth curvature, an increased spatial and temporal resolution in the measurements, the ability to perform multiple-radar measurements, and the capability of optimally and adaptively tasking the individual radars according to the meteorological scene. All of the previous points can be achieved while using less complex radar units than those in operational use today. All of the described potential benefits are governed by relationships between the characteristics of the individual radars composing the network and the network spatial distribution. Using the same network layout for two different classes of radars will create different coverage characteristics. Similarly, deploying one class of radars in two different network layouts will not yield the same coverage results. The relationship between the individual radar characteristics and the resulting network characteristics was presented in (Junyent and Chandrasekar, JAOT, 2009), and applied to both characterization and design of weather radar networks. In this paper, the previously developed radar network characterization analytical and numerical tools are extended to include radar signal attenuation statistics. Signal attenuation is becoming a greater concern as radar systems operating at higher frequencies such as C and X band are becoming commonplace. Attenuation effects when the radar signal is propagating through rain will influence parameters such as minimum detectable reflectivity and number of overlapping radars, which are also dependent both on single radar characteristics and network topology. Taking into account attenuation statistics collected at particular radar operating frequencies in the weather radar network design process, the attenuation margin for both the radar network and the individual radars composing the network can be obtained. Based on the attenuation margins, the number of overlapping of radars capable of sampling a given point in the network in the presence of a given spatial attenuation distribution can also be obtained.

  12. Tangential velocity measurement using interferometric MTI radar

    DOEpatents

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

    2006-01-03

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

  13. CESM: A new category of radar ECCM

    NASA Astrophysics Data System (ADS)

    Johnston, Stephen L.

    1995-02-01

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

  14. Radar frequency radiation

    Microsoft Academic Search

    E. Malowicki

    1981-01-01

    A method is presented for the determination of radar frequency radiation power densities that the PAVE PAWS radar system could produce in its air and ground environment. The effort was prompted by the concern of the people in the vicinity of OTIS AFB MA and BEALE AFB CA about the possible radar frequency radiation hazard of the PAVE PAWS radar.

  15. GMTI MIMO radar

    Microsoft Academic Search

    D. W. Bliss; K. W. Forsythe; S. K. Davis; G. S. Fawcett; D. J. Rabideau; L. L. Horowitz; S. Kraut

    2009-01-01

    Multiple-input multiple-output (MIMO) extensions to radar systems enable a number of advantages compared to traditional approaches. These advantages include improved angle estimation and target detection. In this paper, MIMO ground moving target indication (GMTI) radar is addressed. The concept of coherent MIMO radar is introduced. Comparisons are presented comparing MIMO GMTI and traditional radar performance. Simulations and theoretical bounds for

  16. Spaceborne weather radar

    Microsoft Academic Search

    Robert Meneghini; Toshiaki Kozu

    1990-01-01

    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

  17. Wind shear radar simulation

    NASA Technical Reports Server (NTRS)

    Britt, Charles L.

    1988-01-01

    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.

  18. FM/CW radar system

    NASA Technical Reports Server (NTRS)

    Brey, H.; Geise, P. E., Jr. (inventors)

    1978-01-01

    An FM/CW radar system is presented with improved noise discrimination in which the received signal is multiplied by a sample of the transmitted signal, and the product signal is employed to deflect a laser beam as a function of frequency. The position of the beam is thus indicative of a discrete frequency, and it is detected by the frequency encoded positions of an array of photodiodes. The outputs of the photodiodes are scanned, then threshold detected, and used to obtain the range and velocity of a target.

  19. Imaging radar polarimetry - A review

    NASA Technical Reports Server (NTRS)

    Zebker, Howard A.; Van Zyl, Jakob J.

    1991-01-01

    The authors present a tutorial review of the broad sweep of topics relating to imaging radar polarimetry, ranging from mathematical foundations to hardware and from implementation approaches to signal processing and calibration. The authors examine current developments in sensor technology and implementation for recording polarimetric measurements, and describe techniques and areas of application for this form of remotely sensed data. Those aspects of ground signal processing and calibration peculiar to the polarimetric signals are addressed. Several of the currently operating instruments and some of the implementations planned for future use are discussed.

  20. Detecting and mitigating wind turbine clutter for airspace radar systems.

    PubMed

    Wang, Wen-Qin

    2013-01-01

    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

  1. Comet radar explorer

    NASA Astrophysics Data System (ADS)

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

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

  2. The Italian involvement in Cassini radar

    NASA Astrophysics Data System (ADS)

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

    1991-12-01

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

  3. Determination of the Sources of Radar Scattering

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Zoughi, R.

    1984-01-01

    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.

  4. Highly Integrated Radar Sensor-on-Chip

    NASA Astrophysics Data System (ADS)

    Mende, Ralph

    2012-05-01

    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.

  5. Simulating Line-Of-Sight Radar Returns

    NASA Technical Reports Server (NTRS)

    Moran, F. J.; Phillips, J. D.

    1988-01-01

    Computational method developed to model return signals of ground-mapping radar system for use in simulations where terrain is polygonal form commonly used with computer-generated imagery (CGI). Approach involves fast rejection of polygons not visible to radar return. Technique used to determine which objects in scene visible from specified vantage point and also to determine movements of robot arms avoiding obstacles. Test circles used in algorithm quickly rejects terrain features not traversed by radar line of sight. If circle does not cross line of sight, then all mountains in it rejected.

  6. A transceiver module of the Mu radar

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

  7. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T. (La Jolla, CA)

    1990-01-01

    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.

  8. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T. (La Jolla, CA)

    1990-01-01

    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.

  9. SBRAS — an advanced simulator of spaceborne radar

    Microsoft Academic Search

    Min Wang; Diannong Liang; Haifeng Huang; Zhen Dong

    2007-01-01

    An application-oriented spaceborne radar advanced simulator (SBRAS) is presented in this paper. SBRAS is initiated by the technical and economical requirements to verify formation-flying distributed satellites synthetic aperture radar (SAR) scheme and simplify the instrument hardware design. The simulator develops a full flow of signal processing including formation design, SAR raw data simulation of nature scene, imaging, InSAR processing, digital

  10. Thirty-Two Aircraft Radar Track Simulator

    Microsoft Academic Search

    L. Packer; M. Raphael; H. Saks

    1959-01-01

    This paper describes a Radar Track Simulator which generates the track of thirty-two aircraft in x, y, and h coordinates accurate to one-hundreth of a mile and produces video accurate to one-hundreth of a mile in range, one milliradian in azimuth and two milliradians in elevation. The output video signals are modified by the radar beam pattern, aircraft scintillation noise,

  11. Removal of RFI in wideband radars

    Microsoft Academic Search

    C. T. C. Le; S. Hensley; E. Chapin

    1998-01-01

    The least-mean-square (LMS) adaptive filter is applied to suppress narrow-band radiofrequency interference (RFI) in wideband synthetic aperture radar (SAR) signals. Simulation is used to show the working principles of the adaptive filter and to obtain the optimum filter's parameters. The algorithm is tested with P-band synthetic aperture radar (SAR) data collected by the NASA\\/JPL airborne SAR (AIRSAR) in different noisy

  12. Analysis of local variation of soil surface parameters with TerraSAR-X radar data over bare agricultural fields

    E-print Network

    Paris-Sud XI, Université de

    1 Analysis of local variation of soil surface parameters with TerraSAR-X radar data over bare TerraSAR-X radar data taken over bare soils, and to study the spatial variability of these parameters surfaces from space [3-8]. For bare soils, the radar signal, which depends on various radar parameters

  13. Space communication and radar with lasers

    Microsoft Academic Search

    W. J. Witteman

    2005-01-01

    Sensitive heterodyne detection with lasers applied .to radar and satellite communication is seriously hampered by the large electronic bandwidth due to random Doppler shift and frequency instability. These drawbacks can be circumvented by dual signal heterodyne detection. The system consists of mixing the local oscillator with two signal beams and the lock-in amplification at the beat frequency of the two

  14. Ultrawideband microwave-radar conceptual design

    Microsoft Academic Search

    Merrill Skolnik; Grealie Andrews; J. P. Hansen

    1995-01-01

    This paper outlines the special considerations that characterize the design of an UWB radar for the detection of low-altitude missiles over the sea. It discusses the factors which enter into the choice of frequency, and the selection of the transmitter, antenna, and receiver. Reviewed are signal processing issues concerning detection of UWB signals in noise and clutter, nondoppler MTI based

  15. Multistatic Synthetic Aperture Radar Image Formation

    Microsoft Academic Search

    V. Krishnan; J. Swoboda; Can Evren Yarman; Birsen Yazici

    2010-01-01

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

  16. Combustion powered thermophotovoltaic emitter system

    SciTech Connect

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

    1995-07-01

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

  17. SMAP RADAR Processing and Calibration

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  18. Radar images analysis for scattering surfaces characterization

    NASA Astrophysics Data System (ADS)

    Piazza, Enrico

    1998-10-01

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

  19. Development of optical field emitter arrays

    E-print Network

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

    2013-01-01

    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 ...

  20. Shielding in ungated field emitter arrays

    NASA Astrophysics Data System (ADS)

    Harris, J. R.; Jensen, K. L.; Shiffler, D. A.; Petillo, J. J.

    2015-05-01

    Cathodes consisting of arrays of high aspect ratio field emitters are of great interest as sources of electron beams for vacuum electronic devices. The desire for high currents and current densities drives the cathode designer towards a denser array, but for ungated emitters, denser arrays also lead to increased shielding, in which the field enhancement factor ? of each emitter is reduced due to the presence of the other emitters in the array. To facilitate the study of these arrays, we have developed a method for modeling high aspect ratio emitters using tapered dipole line charges. This method can be used to investigate proximity effects from similar emitters an arbitrary distance away and is much less computationally demanding than competing simulation approaches. Here, we introduce this method and use it to study shielding as a function of array geometry. Emitters with aspect ratios of 102-104 are modeled, and the shielding-induced reduction in ? is considered as a function of tip-to-tip spacing for emitter pairs and for large arrays with triangular and square unit cells. Shielding is found to be negligible when the emitter spacing is greater than the emitter height for the two-emitter array, or about 2.5 times the emitter height in the large arrays, in agreement with previously published results. Because the onset of shielding occurs at virtually the same emitter spacing in the square and triangular arrays, the triangular array is preferred for its higher emitter density at a given emitter spacing. The primary contribution to shielding in large arrays is found to come from emitters within a distance of three times the unit cell spacing for both square and triangular arrays.

  1. A new method of emittance measurement for electron beams from the Micro-emitter

    Microsoft Academic Search

    Hiroshi Ishizuka; Yuriko Nakahara; Sunao Kawasaki; Stephen Musyoki; Hiroshi Shimizu; Akihiko Watanabe; Makoto Shiho

    1994-01-01

    Recently a new type of cathode called Micor-emitter has been put in progress. This cathode is a microfabricated field emitter having the characteristics of very low emittance and high brightness. We cannot measure the emittance of the cathode with conventional methods like the pepper-pot method. The reasons are: (1) the angle between the electron orbit and the axis is very

  2. Ultra Low Emittance Light Sources

    SciTech Connect

    Bengtsson,J.

    2008-06-23

    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.

  3. Teaching the common emitter amplifier

    Microsoft Academic Search

    Mark D Ellse

    1984-01-01

    If one wishes to teach some device electronics in schools it will have to be very limited. It is not productive to measure all the common emitter and common base characteristics of the bipolar transistor as required by at least one A-level syllabus. To do so wastes pupil time and leads to considerable confusion. Nor should the study be extended

  4. Soviet oceanographic synthetic aperture radar (SAR) research

    SciTech Connect

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

    1991-01-01

    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.

  5. FPGA based Ultra-Wideband pseudo-noise radar

    Microsoft Academic Search

    Amutha Jayakumar; Asha Durafe

    2011-01-01

    A high accuracy experimental platform for Ultra Wide Band (UWB) PN radar performance evaluation has been created. This PN radar platform could be used for the applications such as unmanned- aerial-vehicle anti-collision and short-range distance measurement etc (3). It includes compact size X-band radar transceiver, baseband signal processing in FPGA, high speed analog to digital converter (ADC), and Matlab tools.

  6. Radar backscatter modelling

    NASA Astrophysics Data System (ADS)

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

    1984-04-01

    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.

  7. Sensitivity and signal to noise ratio improvement of a one micron ladar system incorporating a neodymium doped optical fiber preamplifier. Laser radar testbed

    Microsoft Academic Search

    Michael S. Salisbury

    1994-01-01

    In an effort to increase the signal to noise ratio of a continuous wave, one micron all solid state ladar system, a rare earth doped optical fiber amplifier has been investigated as a preamplifier for ladar return signals. This details the experimental system used and provides a theoretical analysis of the fiber amplifier's effect on heterodyne and direct detection. The

  8. Nonlocality from N>2 independent single-photon emitters

    Microsoft Academic Search

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

    2010-01-01

    We demonstrate that intensity correlations of second order in the fluorescence light of N>2 single-photon emitters may violate locality while the visibility of the signal remains below 1\\/(2)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

  9. Nonlocality from N>2 independent single-photon emitters

    Microsoft Academic Search

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

    2010-01-01

    We demonstrate that intensity correlations of second order in the fluorescence light of N>2 single-photon emitters may violate locality while the visibility of the signal remains below 1\\/2≈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

  10. Multi-damage Detection with Embedded Ultrasonic Structural Radar Algorithm using Piezoelectric Wafer

    E-print Network

    Giurgiutiu, Victor

    -time Fourier transform and continuous wavelet transform for time-frequency analysis, continuous wavelet damage. The signal processing methods include discrete wavelet transform for signal denoising, short structural radar, piezoelectric wafer active sensor, signal processing, de-noising, Continuous Wavelet

  11. Remorque RADAR Description technique

    E-print Network

    Heurteaux, Yanick

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

  12. Waveform Design for Multistatic Radar Detection

    Microsoft Academic Search

    Steven Kay

    2009-01-01

    We derive the optimal Neyman-Pearson (NP) detector and its performance, and then present a methodology for the design of the transmit signal for a multistatic radar receiver. The detector assumes a Swerling I extended target model as well as signal-dependent noise, i.e., clutter. It is shown that the NP detection performance does not immediately lead to an obvious signal design

  13. Radar and sonar probing of potash 

    E-print Network

    Lopez Aguilar, Luis Felipe

    1986-01-01

    parameters are listed in Table 5. 21 Table 4. Linear sonar transmitter/receiver specifications Pulsed power output Operating frequency Type transmission Source level Minimum detectable signal Range scales Pulse lengths Pulse repetition rate Power... did not penetrate the potash and no signals were recovered. The large saturated signals observed for 3. 5 to 4. 0 microseconds are attributed to reverberation from the mine walls. The Foxtrot system is a high-resolution, pulsed radar operating at 4...

  14. On the sensitivity of weather radars

    Microsoft Academic Search

    Paul L. Smith

    1986-01-01

    This paper discusses the subject of weather radar system sensitivity from a general point of view, with emphasis on the influence of wavelength. Expressions for the echo signal-to-noise ratio are examined using a detection theory approach to develop factors describing the effects of different signal processing techniques. Then the variation of the equivalent signal-to-noise ratio with wavelength under certain typical

  15. Cassini Titan Radar Mapper

    Microsoft Academic Search

    CHARLES ELACHI; E. Im; L. E. Roth; C. L. Werner

    1991-01-01

    The Cassini Titan Radar Mapper is a multimode radar instrument designed to probe the optically inaccessible surface of Titan, Saturn's largest moon. The instrument is to be included in the payload of the Cassini Saturn Mission, scheduled for launch in 1995. The individual modes of Cassini Radar Mapper will allow topographic mapping and surface imaging at few hundred meters resolution.

  16. Lunar radar backscatter studies

    NASA Technical Reports Server (NTRS)

    Thompson, T. W.

    1979-01-01

    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.

  17. Inverse synthetic aperture 3-D imaging laser radar

    Microsoft Academic Search

    Jin He; Xiao-you Yang; Jian-feng Wang; Qun Zhang

    2010-01-01

    Three-dimensional (3-D) Image can represent target's physical characteristic well and improve target recognition capability, however, conventional optical imaging radar which is limited by the array units or scan system cannot realize the high resolution imaging for moving targets. This paper combines the inverse synthetic aperture technology, laser signal and interferometric technique to suggest a new radar system which is called

  18. Ambiguity Functions for Spatially Coherent and Incoherent Multistatic Radar

    Microsoft Academic Search

    T. Derham; S. Doughty; C. Baker; K. Woodbridge

    2010-01-01

    The ambiguity function is a key tool for determining the target resolution capability of a radar system. Recently, multistatic radar systems have been proposed where target detection is jointly performed on a vector of captured signals arising from multiple spatially dispersed transmitters and\\/or receivers. In the work presented here, expressions for the ambiguity functions of such systems are derived based

  19. Information-theoretic structure of multistatic radar imaging

    Microsoft Academic Search

    Zachary Chance; Raghu G. Rajy; David J. Love

    2011-01-01

    Using an information theoretical perspective, we explore quantitative methods for exploiting the spatial diversity offered by multiple widely separated antennas for radar imaging applications. While decomposing the operation of multistatic radar into multiple bistatic components, we proceed to character- ize relevant conditional mutual information quantities between the underlying channel and bistatic output signals. The target scene is statistically characterized to

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

    Microsoft Academic Search

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

    2010-01-01

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

  1. Performance analysis of various UWB radar approaches for medical diagnostics

    Microsoft Academic Search

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

    2011-01-01

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

  2. Space-time adaptive processing for airborne radar

    Microsoft Academic Search

    James Ward

    1994-01-01

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

  3. A 24GHz CMOS RF Transceiver for Car Radar Applications

    E-print Network

    Nam, Sangwook

    System Design 2.1 Overall Architecture In FMCW radar system, detection range and minimum detectable incoming interference signal. Also, when array system is adopted to increase detection range, phaseA 24GHz CMOS RF Transceiver for Car Radar Applications # Sungho Lee 1,2 , Kyoungwon Min1

  4. Recent Breakthroughs in RF Photonics for Radar Systems

    Microsoft Academic Search

    K. Garenaux; T. Merlet; M. Alouini; J. Lopez; N. Vodjdani; R. Boula-Picard; C. Fourdin; J. Chazelas

    2007-01-01

    Radar systems require transmission of very high purity signals. Photonics is now mature enough to achieve analog transmission with very low noise, strong immunity, and wide-bandwidth even in harsh environments. We present our recent developments of optimized optical links dedicated to radar and multifunction systems

  5. Analysis of Eccentered Dipole Antenna for Borehole Radar

    Microsoft Academic Search

    Satoshi Ebihara; Yoshihiro Inoue

    2009-01-01

    A dipole antenna in a borehole may be placed away from the center of the borehole, and this eccentricity produces additional complicated electromagnetic fields, which may influence borehole radar signals. In this paper, we analyze an eccentric dipole antenna in a borehole for borehole radars. Our approach is an extended version of the pseudoanalytical formulation that was previously applied for

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

    E-print Network

    Boyer, Edmond

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

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

    E-print Network

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

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

    E-print Network

    Paris-Sud XI, Université de

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

  9. Near field focusing algorithm for high frequency ground penetration imaging radar

    Microsoft Academic Search

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

    1999-01-01

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

  10. Performance analysis of pulse Doppler digital radars with application to the Shuttle Ku-band system

    Microsoft Academic Search

    W. K. Alem; C. L. Weber

    1978-01-01

    A pulse Doppler digital radar is one of the primary components of the Ku-band integrated radar and communication equipment on the Space Shuttle. The performance of the Ku-band rendezvous radar to be used on the Space Shuttle is analyzed in four parts. First an overall functional block diagram description is presented to illustrate the signal processing in the detection and

  11. Adaptive Space/Frequency Processing for Distributed Aperture Radars Raviraj Advea

    E-print Network

    Adve, Raviraj

    or orthogonal signals). Multistatic radars can provide significantly improved target tracking and interferenceAdaptive Space/Frequency Processing for Distributed Aperture Radars Raviraj Advea , Richard baseline of such a distributed radar results in angular resolution that is orders of magnitude better than

  12. Imaging method: A strong tool for moving target tracking by a multistatic UWB radar system

    Microsoft Academic Search

    D. Kocur; J. Gamec; M. Svecova; M. Gamcova; J. Rovnakova

    2010-01-01

    In this paper, imaging method for moving target tracking by a multistatic ultra-wideband radar system is described. The task of moving target tracking consists in estimation of a target trajectory based on processing of raw radar data obtained from all receiving channels of a radar system. Then, the imaging method applied for target tracking consists of such signal processing phases

  13. MULTISTATIC PASSIVE RADAR IMAGING USING THE SMOOTHED PSEUDO WIGNER-VILLE DISTRIBUTION

    E-print Network

    Lanterman, Aaron

    MULTISTATIC PASSIVE RADAR IMAGING USING THE SMOOTHED PSEUDO WIGNER-VILLE DISTRIBUTION Yong Wu investigate passive radar imaging of aircraft using reflected TV signals. We apply a Smoothed Pseudo Wigner. In the second simulation, a more re- alistic simulated passive radar dataset is used. A set of in- stantaneous

  14. Synthetic Signatures of Volcanic Ash Cloud Particles From X-Band Dual-Polarization Radar

    Microsoft Academic Search

    Frank Silvio Marzano; Errico Picciotti; Gianfranco Vulpiani; Mario Montopoli

    2012-01-01

    Weather radar retrieval, in terms of detection, estimation, and sensitivity, of volcanic ash plumes is dependent not only on the radar system specifications but also on the range and ash cloud distribution. The minimum detectable signal can be increased, for a given radar and ash plume scenario, by decreasing the observation range and increasing the operational frequency and also by

  15. A Time Series Weather Radar Simulator Based on High-Resolution Atmospheric Models

    Microsoft Academic Search

    B. L. Cheong; R. D. Palmer; M. Xue

    2008-01-01

    A three-dimensional radar simulator capable of generating simulated raw time series data for a weather radar has been designed and implemented. The characteristics of the radar signals (amplitude, phase) are derived from the atmospheric fields from a high-resolution numerical weather model, although actual measured fields could be used. A field of thousands of scatterers is populated within the field of

  16. The Design of a High Performance MMW Radar System for Autonomous Land Vehicle Navigation

    Microsoft Academic Search

    S. Clark; H. Durrant Whyte

    This paper describes the design of a high performance 77GHz millimetre wave radar, signal processing and control system for use in autonomous vehicle navigation. The radar front end and intermediate frequency components are described together with a method of distinguishing pre-placed target beacons from other reflectors using the polarisation of the reflected signal. Digital signal processing hardware is described which

  17. Comparison between UWB and CW radar sensors for breath activity monitoring

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

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

  19. Metamaterial selective emitters for photodiodes

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

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

    PubMed

    Crothers, Laura R; Cummings, Molly E

    2013-05-01

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

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

    Microsoft Academic Search

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

    2000-01-01

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

  2. Combustion powered thermophotovoltaic emitter system

    SciTech Connect

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

    1995-12-31

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

  3. Radar Meteorology Tutorial

    NSDL National Science Digital Library

    McNoldy, Brian

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

  4. Transverse Emittance Reduction with Tapered Foil

    SciTech Connect

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

    2011-12-09

    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.

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

    E-print Network

    Scerri, Paul

    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

  6. Two terminal micropower radar sensor

    DOEpatents

    McEwan, Thomas E. (Livermore, CA)

    1995-01-01

    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.

  7. Radar waveform diversity for tracking

    NASA Astrophysics Data System (ADS)

    Grishin, Yury

    2009-06-01

    The paper presents a brief survey of the main approaches for solving the problem of radar waveform selection for optimal tracking. The traditional approach to the system design has been to treat the detection and tracking subsystems as completely separate entities. In last years some new types of radars equipped with highly agile software driven waveform generators have appeared. This makes it possible to change the transmitted waveform at each time step for obtaining minimal tracking errors. Thus the problem of the waveform selection can be formulated as the optimisation problem of the following form: for given class of signals and target movement model to find the tracking filter structure and waveform parameter sequence which result in a minimum variance estimate of the target state vector. Two main approaches to waveform optimising have been considered in the paper: the control theoretic approach and information theoretic approach. The relationships between sensor characteristics and tracking algorithm are discussed.

  8. Two terminal micropower radar sensor

    DOEpatents

    McEwan, T.E.

    1995-11-07

    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.

  9. Modern Radar Techniques for Geophysical Applications: Two Examples

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    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.

  10. Radar systems for a polar mission, volume 1

    NASA Technical Reports Server (NTRS)

    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

    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.

  11. Development of a Low-Cost UAV Doppler Radar Data System

    NASA Technical Reports Server (NTRS)

    Knuble, Joseph; Li, Lihua; Heymsfield, Gerry

    2005-01-01

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

  12. Sensitivity and signal to noise ratio improvement of a one micron ladar system incorporating a neodymium doped optical fiber preamplifier. Laser radar testbed

    NASA Astrophysics Data System (ADS)

    Salisbury, Michael S.

    1994-02-01

    In an effort to increase the signal to noise ratio of a continuous wave, one micron all solid state ladar system, a rare earth doped optical fiber amplifier has been investigated as a preamplifier for ladar return signals. This details the experimental system used and provides a theoretical analysis of the fiber amplifier's effect on heterodyne and direct detection. The SNR is plotted as a function of the return signal power, and a SNR threshold defines a minimum detectable signal power. The return signals required to attain the SNR threshold are compared for four cases: direct detection with and without the fiber amplifier, and heterodyne detection with and without the fiber amplifier. For direct detection, these results predict a sensitivity increase of 21.0 dB, yet for heterodyne detection the predicted sensitivity increase is only 4.0 dB. These SNR equations are then used to predict experimental improvements of 42.0 dB and 4.0 dB for the direct detection and heterodyne detection experiments, respectively. Experimentally measured increases in SNR are then compared to these predictions. Specifically, for direct detection a SNR increase of 36.5 dB has been measured, and for heterodyne detection the experimental work yielded an increase of 8.0 dB.

  13. Ultrafast oscilloscope based on laser-triggered field emitters.

    PubMed

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

    2015-01-15

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

  14. FREQUENCY DEPENDENT ATTENUATION ANALYSIS OF GROUND-PENETRATING RADAR DATA

    E-print Network

    Barrash, Warren

    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

  15. Comparison between radar and rain gauges data at different distances from radar and correlation existing between the rainfall values in the adjacent pixels

    NASA Astrophysics Data System (ADS)

    Sebastianelli, S.; Russo, F.; Napolitano, F.; Baldini, L.

    2010-07-01

    Rainfall intensity data in pixels very far from radar are less correlated than values in pixels near the radar, because at far distances the width of a range-bin is comparable or bigger than the pixel width, so in a pixel there are one or just a few rainfall intensity values. Vice versa, near the radar, there are many radar resolution bins which belong to a single pixel, so great correlation between rainfall intensity values for contiguous pixels is expected. Moreover, the signal returned from precipitation at far distance from radar antenna can be due to a radar sample volume partially or completely filled with mixed phase or ice particles, or can be quite close to the minimum detectable signal. All these phenomena can influence the goodness of rainfall estimates, introducing errors which increase as the distance from radar increases. The objective of this work is to characterize these errors as a function of the distance. For this aim is possible to compare the rainfall data obtained by rain gauges at different distances from radar with rainfall radar data at the same distances, verifying the correlation existing between the rainfall values in the adjacent pixels and how the difference between radar and rain gauges data changes. The radar data utilized in this work have been collected from the CNR-ISAC (Institute of Atmospheric Sciences and Climate of the National Research Council) Polar 55C radar in Rome Tor Vergata during 2008.

  16. Alpine radar conversion for LAWR

    NASA Astrophysics Data System (ADS)

    Savina, M.; Burlando, P.

    2012-04-01

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

  17. Emittance, surface structure, and electron emission

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  18. Study to investigate and evaluate means of optimizing the Ku-band combined radar\\/communication functions for the space shuttle

    Microsoft Academic Search

    C. L. Weber; S. Udalov; W. Alem

    1977-01-01

    The performance of the space shuttle orbiter's Ku-Band integrated radar and communications equipment is analyzed for the radar mode of operation. The block diagram of the rendezvous radar subsystem is described. Power budgets for passive target detection are calculated, based on the estimated values of system losses. Requirements for processing of radar signals in the search and track modes are

  19. EMITTANCE CONTROL FOR VERY SHORT BUNCHES

    SciTech Connect

    Bane, K

    2004-07-20

    Many recent accelerator projects call for the production of high energy bunches of electrons or positrons that are simultaneously short, intense, and have small emittances. Examples of such projects are the Self-Amplified Spontaneous Emission (SASE) FEL's, such as the Linac Coherent Light Source (LCLS). A major challenge is keeping in check forces that increase beam emittances in accelerator components, such as: wakefields of accelerator structures and surface roughness, and coherent synchrotron radiation. We describe such forces and discuss emittance control.

  20. Emittance Growth in the NLCTA First Chicane

    SciTech Connect

    Sun, Yipeng; Adolphsen, Chris; /SLAC

    2011-08-19

    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.

  1. Common-Emitter Transistor Video Amplifiers

    Microsoft Academic Search

    Georg Bruun

    1956-01-01

    A design procedure and theory are given for the common-emitter transistor video amplifier with and without a feedback resistor in the emitter lead. In the analysis a junction transistor of the alloy type is represented by the Johnson-Giacoletto hybrid-pi equivalent circuit for the common-emitter transistor. The design theory accounts for the most significant part of the bilateralness of the transistor

  2. A new method of emittance measurement for electron beams from the Micro-emitter

    NASA Astrophysics Data System (ADS)

    Ishizuka, Hiroshi; Nakahara, Yuriko; Kawasaki, Sunao; Musyoki, Stephen; Shimizu, Hiroshi; Watanabe, Akihiko; Shiho, Makoto

    1994-03-01

    Recently a new type of cathode called Micor-emitter has been put in progress. This cathode is a microfabricated field emitter having the characteristics of very low emittance and high brightness. We cannot measure the emittance of the cathode with conventional methods like the pepper-pot method. The reasons are: (1) the angle between the electron orbit and the axis is very small and (2) we cannot focus the electron beam in the vacuum or on the surface of the material since the current density of the cathode is extremely high. For the emittance measurement for such low emittance and high brightness cathode, we need to expand the beam, and measure the beam's cross section without any slits or apertures. We studied and proposed a new emittance measurement method for the Micro-emitter.

  3. Directional emittance corrections for thermal infrared imaging

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

  4. Directional emittance corrections for thermal infrared imaging

    NASA Astrophysics Data System (ADS)

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

    1992-04-01

    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.

  5. Directional emittance corrections for thermal infrared imaging

    NASA Astrophysics Data System (ADS)

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

    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.

  6. Minimum emittance in TBA and MBA lattices

    NASA Astrophysics Data System (ADS)

    Xu, Gang; Peng, Yue-Mei

    2015-03-01

    For reaching a small emittance in a modern light source, triple bend achromats (TBA), theoretical minimum emittance (TME) and even multiple bend achromats (MBA) have been considered. This paper derived the necessary condition for achieving minimum emittance in TBA and MBA theoretically, where the bending angle of inner dipoles has a factor of 31/3 bigger than that of the outer dipoles. Here, we also calculated the conditions attaining the minimum emittance of TBA related to phase advance in some special cases with a pure mathematics method. These results may give some directions on lattice design.

  7. PROTON BEAM EMITTANCE GROWTH AT RHIC

    SciTech Connect

    ZHANG,S.; PTITSYN, V.

    2007-06-25

    With significant beam intensity improvement in RHIC polarized proton runs in 2005 and 2006, the emittance growth becomes a luminosity limiting factor. The beam emittance growth has a dependence on the dynamic pressure rise, which in RHIC proton runs is mainly caused by the electron cloud. The beam instability is usually absent, and the emittance growth rate is much slower than the ones caused by the head-tail instability. It is suspected that the emittance growth is caused by the electron cloud below the instability threshold.

  8. Apollo experience report: Lunar module landing radar and rendezvous radar

    NASA Technical Reports Server (NTRS)

    Rozas, P.; Cunningham, A. R.

    1972-01-01

    A developmental history of the Apollo lunar module landing and rendezvous radar subsystems is presented. The Apollo radar subsystems are discussed from initial concept planning to flight configuration testing. The major radar subsystem accomplishments and problems are discussed.

  9. An overview of impulse radar phenomenon

    Microsoft Academic Search

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

    1992-01-01

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

  10. The Multiple Doppler Radar Workshop, November 1979

    Microsoft Academic Search

    R. E. Carbone; F. I. Harris; P. H. Hildebrand; R. A. Kropfli; L. J. Miller; W. Moninger; R. G. Strauch; R. J. Doviak; K. W. Johnson; S. P. Nelson; P. S. Ray; M. Gilet

    1980-01-01

    The findings of the Multiple Doppler Radar Workshop are summarized by a series of six papers. Part I of this series briefly reviews the history of multiple Doppler experimentation, fundamental concepts of Doppler signal theory, and organization and objectives of the Workshop. Invited presentations by dynamicists and cloud physicists are also summarized.Experimental design and procedures (Part II) are shown to

  11. Interkosmos laser radar for satellite tracking

    Microsoft Academic Search

    P. S. Dixit; P. K. Rao

    1980-01-01

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

  12. Outdoor Radar Mapping Using Measurement Likelihood Estimation

    Microsoft Academic Search

    John Mullane; Martin David Adams; Wijerupage Sardha Wijesoma

    2007-01-01

    Summary. This paper fuses target detection and occupancy mapping theory to develop an improved method for outdoor mapping with a radar sensor. It is shown that the occupancy mapping problem is directly coupled with the signal detection processing which occurs in a range sensor, and that the required measurement like- lihoods are those commonly encountered in both the target detection

  13. Course Syllabus Weather Radar Theory and Practice

    E-print Network

    Droegemeier, Kelvin K.

    Motivation and Historical Perspective of Weather Radar Chapter 2 Electromagnetic Waves and Propagation and P. Hobbs, 2006 Fundamentals of Signals and Systems, 2nd Ed, E. W. Kamen and B. S. Heck, 2000 Probability, Random Variables, and Stochastic Processes, 3rd Ed, A. Papoulis, 1991 Fundamental of Applied

  14. Quantification of Reflection Patterns in Ground-Penetrating Radar Data

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

    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.

  15. Observation and theory of the radar aurora

    SciTech Connect

    Sahr, J.D.

    1990-01-01

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

  16. Staggered Costas signals

    Microsoft Academic Search

    Avraham Freedman; Nadav Levanon

    1986-01-01

    A radar signal, based on coherent processing of a train of staggered Costas (1984) bursts is based on a minimum number of collocation of their individual ambiguity function sidelobe peaks. The resulting ambiguity function combines qualities of both 'thumbtack' and 'bed of nails' signals. Comparison with linear-FM, V-FM, and complementary phase coded signals is given, as well as comparison with

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

    E-print Network

    Vaidyanathan, P. P.

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

  18. Radar in transition

    NASA Astrophysics Data System (ADS)

    Barton, D. K.

    1984-12-01

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

  19. Fiber optic relayed laser radar

    NASA Astrophysics Data System (ADS)

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

    1995-08-01

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

  20. Radar performance improvement

    Microsoft Academic Search

    G. R. Little

    1976-01-01

    The AN\\/APQ-153 fire control radar modified to provide angle tracking was evaluated for improved performance. The frequency agile modifications are discussed along with the range-rate improvement modifications, and the radar to computer interface. A parametric design and comparison of noncoherent and coherent radar systems are presented. It is shown that the shuttle rendezvous range and range-rate requirements can be made

  1. Caribbean Radar Cases

    NSDL National Science Digital Library

    2014-09-14

    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.

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

    NASA Astrophysics Data System (ADS)

    Prasath, V. B. Surya; Haddad, Oussama

    2014-01-01

    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.

  3. Design and realization of a multimission-capable 70 GHz FM/CW radar reception system

    NASA Astrophysics Data System (ADS)

    Kreutzer, E.

    1982-01-01

    A radar which can present three-dimensional scenes on a two-dimensional screen at intervals of a few hundredths of a second is described. Signal and system theory for FM/CW radars is first reviewed, and the system design for the FM/CW radar under consideration is presented. A comparative signal analysis of two radar reception systems is given, and the effect of nonideal FM/CW signals on the orientation spectrum is considered. Finally, the realization and technical measurement testing of the system are addressed.

  4. Equatorial radar system

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    A large clear air radar with the sensitivity of an incoherent scatter radar for observing the whole equatorial atmosphere up to 1000 km altitude is now being designed in Japan. The radar, called the Equatorial Radar, will be built in Pontianak, Kalimantan Island, Indonesia (0.03 N, 109.3 E). The system is a 47 MHz monostatic Doppler radar with an active phased array configuration similar to that of the MU radar in Japan, which has been in successful operation since 1983. It will have a PA product of more than 5 x 10(9) sq. Wm (P = average transmitter power, A = effective antenna aperture) with sensitivity more than 10 times that of the MU radar. This system configuration enables pulse-to-pulse beam steering within 25 deg from the zenith. As is the case of the MU radar, a variety of sophisticated operations will be made feasible under the supervision of the radar controller. A brief description of the system configuration is presented.

  5. The Invisible Radar Triangle

    NSDL National Science Digital Library

    2014-09-18

    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.

  6. Generalized radar/radiometry imaging problems

    E-print Network

    Genève, Université de

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

  7. Comparative analyses for the prediction of streamflow from small watershed by use of digitized radar data 

    E-print Network

    Braatz, Dean Thomas

    1973-01-01

    characteristics of the WSR-57. Table 2. Characteristics of the WSR-57 weather radar used by NSSL. (Source: NWS, NOAA) Band Wavelength Peak power Pulse repetition frequency (PRF) Pulse length Minimum detectable signal Beam wid th Antenna gain Normal scan... on radar data, After several years of development, the automatic radar- signal processing and data communication system is undergoing evaluation during the testing period of the D/RADEX as to its operational performance. Basically, each automatic...

  8. Thermophotovoltaic Generators Using Selective Metallic Emitters

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  9. Modern signal processing

    NASA Astrophysics Data System (ADS)

    Kailath, T.

    An instructional and reference manual concerning the design and applications of signal processing systems is presented. Among the specific topics addressed are: advanced filter design; speech processing; and communications processing. Attention is also given to: radar and sonar signal processing; image processing; sophisticated analog signal processing devices; and VLSI technologies. The relations between signal processing algorithms, special purpose hardware architectures; and mathematical principles of signal processing techniques are also considered.

  10. Selective Emitter Pumped Rare Earth Laser

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

  11. Emittance Growth in a Plasma Wakefield Accelerator

    E-print Network

    Mete, O; Xia, G; Labiche, M

    2015-01-01

    The interaction of the witness beam with the surrounding plasma particles and wakefields was studied. The impli- cations of the elastic scattering process on beam emittance and, emittance evolution under the focusing and acceleration provided by plasma wakefields were discussed. Simulations results from GEANT4 are presented in this paper.

  12. Turbulent scattering for radars: A summary

    NASA Astrophysics Data System (ADS)

    Lübken, Franz-Josef

    2014-01-01

    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.

  13. Bistatic radar studies of the planets

    NASA Technical Reports Server (NTRS)

    Linscott, Ivan R.; Tyler, G. Leonard; Marouf, Essam A.; Simpson, Richard A.

    1991-01-01

    The use of bistatic radar for planetary studies is discussed with the objective of presenting important, new capabilities for spaceborne systems. The success of bistatic radar, as a probe of the solar system's planets and moons, is reviewed. The relevance of new micropower and signal processing technologies is assessed, and the scientific opportunities for extending the study of planetary surfaces, atmospheres, and rings are presented. Ground based and spaceborne systems are discussed. The study of planetary surfaces, atmospheres, and rings is reviewed. The opportunities presented by the Next Generation Explorer (NGE) equipped with these new technologies are summarized.

  14. Emittance measurements of the CLIO electron beam

    NASA Astrophysics Data System (ADS)

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

    1997-02-01

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

  15. SMAP Radar Processing and Expected Performance

    NASA Astrophysics Data System (ADS)

    West, R. D.; Jaruwatanadilok, S.

    2011-12-01

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

  16. Facilitating cloud radar and lidar algorithms: the Cloudnet Instrument Synergy/Target Categorization product

    E-print Network

    Hogan, Robin

    estimates of their associated error. Instrument sensitivity: Knowledge of the minimum de- tectable signal of the radar allows one to take account of clouds that may not be detected in comparisons with a model. Data quality flags: These inform the user when signals are contaminated by ground clutter, unknown radar atten

  17. Java Radar Analysis Tool

    NASA Technical Reports Server (NTRS)

    Zaczek, Mariusz P.

    2005-01-01

    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.

  18. Noncooperative rendezvous radar system

    NASA Technical Reports Server (NTRS)

    1974-01-01

    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.

  19. Decoders for MST radars

    NASA Technical Reports Server (NTRS)

    Woodman, R. F.

    1983-01-01

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

  20. Phased-array radars

    Microsoft Academic Search

    Eli Brookner

    1985-01-01

    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

  1. Determination of radar MTF

    SciTech Connect

    Chambers, D. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    The ultimate goal of the Current Meter Array (CMA) is to be able to compare the current patterns detected with the array with radar images of the water surface. The internal wave current patterns modulate the waves on the water surface giving a detectable modulation of the radar cross-section (RCS). The function relating the RCS modulations to the current patterns is the Modulation Transfer Function (MTF). By comparing radar images directly with co-located CMA measurements the MTF can be determined. In this talk radar images and CMA measurements from a recent experiment at Loch Linnhe, Scotland, will be used to make the first direct determination of MTF for an X and S band radar at low grazing angles. The technical problems associated with comparing radar images to CMA data will be explained and the solution method discussed. The results suggest the both current and strain rate contribute equally to the radar modulation for X band. For S band, the strain rate contributes more than the current. The magnitude of the MTF and the RCS modulations are consistent with previous estimates when the wind is blowing perpendicular to the radar look direction.

  2. Positron emitter labeled enzyme inhibitors

    DOEpatents

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

    1987-05-22

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

  3. Microlensless interdigitated photoconductive terahertz emitters.

    PubMed

    Singh, Abhishek; Prabhu, S S

    2015-01-26

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

  4. Looking at Radar Images

    NSDL National Science Digital Library

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

  5. SOURCESCAT - A very fine resolution radar scatterometer

    NASA Astrophysics Data System (ADS)

    Zoughi, R.; Wu, L. K.; Moore, R. K.

    1985-11-01

    A short-range, high resolution FM-CW radar system has been used to investigate the sources of backscatter in various types of crops, trees, surfaces and man-made targets. A transmitted signal bandwidth of 2.0 GHz at 10.0 GHz center frequency provides a range resolution of 11 cm. A focused parabolic antenna, providing narrow effective antenna beamwidths in both the azimuth and the elevation directions, gives a 16 cm illumination area diameter at a target range of 4.0 m. Amplitude weighting of the received signal is implemented to reduce range sidelobe levels due to the internal system reflections and leakage signals from the transmitter into the receiver. Due to this amplitude weighting, the range resolution is 11.0 cm, rather than the 6.6 cm possible with 2 GHz bandwidth. This report discusses the design steps taken in construction of their radar system.

  6. 4748 IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 62, NO. 18, SEPTEMBER 15, 2014 IRCI Free Range Reconstruction for SAR Imaging

    E-print Network

    Xia, Xiang-Gen

    ORTHOGONAL frequency-division multiplexing (OFDM) signals are firstly presented for radar signal processing in [1], and recently studied and used in radar appli- cations, such as moving target detection [2 access (WiMAX) signals, are also investigated for radar applications in [7]­[12]. Using OFDM signals

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

    SciTech Connect

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

    1994-11-18

    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.

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

    SciTech Connect

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

    1994-12-19

    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.

  9. 162 IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 33, NO. 1, JANUARY 1995 Behavior of the Ocean Radar Cross-

    E-print Network

    Miami, University of

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

  10. Performance of Scanning Millimeter-Wave Radar in a Tropical Environment Jorge M. Villa and Sandra L. Cruz-Pol

    E-print Network

    Cruz-Pol, Sandra L.

    : sekelsky@mirls.ecs.umass.edu Abstract-The minimum detectable radar reflectivity (dBZemin) is computed radiometer measurements are used to model radar signal extinction for the Maritime Continent ThunderstormPerformance of Scanning Millimeter-Wave Radar in a Tropical Environment Jorge M. Villa and Sandra L

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

    NASA Technical Reports Server (NTRS)

    Statman, Joseph; Jamnejad, Vahraz; Nguyen, Lee

    2012-01-01

    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.

  12. Development and characterization analysis of a radar polarimeter

    NASA Technical Reports Server (NTRS)

    Bong, S.; Blanchard, A. J.

    1983-01-01

    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.

  13. Threshold Calculation for Coherent Detection in Dual-Polarization Weather Radars

    Microsoft Academic Search

    Igor R. Ivic; Dusan S. Zrnic; Tian-You Yu

    2012-01-01

    It is customary to censor signals in conventional weather radar using estimates of signal-to-noise ratio (SNR) and\\/or magnitude of autocorrelation coefficient at lag one. Dual-polarized weather radar provides a pair of highly correlated signals from the two orthogonally polarized returns. A novel censoring technique, previously proposed, sums powers, autocorrelations, and correlation between signals in the two channels and compares the

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

    NASA Astrophysics Data System (ADS)

    Shuai, Yong; Tan, Heping; Liang, Yingchun

    2014-03-01

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

  15. Rendezvous radar for the orbital maneuvering vehicle

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    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.

  16. Rendezvous radar for the orbital maneuvering vehicle

    NASA Astrophysics Data System (ADS)

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

    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.

  17. Optically isolated signal coupler with linear response

    DOEpatents

    Kronberg, James W. (Aiken, SC)

    1994-01-01

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

  18. L-band radar sensing of soil moisture

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    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.

  19. Use and Interpretation of Radar

    NSDL National Science Digital Library

    John Nielsen-Gammon

    1996-01-01

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

  20. Radar remote sensing in biology

    USGS Publications Warehouse

    Moore, Richard K.; Simonett, David S.

    1967-01-01

    The present status of research on discrimination of natural and cultivated vegetation using radar imaging systems is sketched. The value of multiple polarization radar in improved discrimination of vegetation types over monoscopic radars is also documented. Possible future use of multi-frequency, multi-polarization radar systems for all weather agricultural survey is noted.

  1. Multinozzle Emitter Arrays for Nanoelectrospray Mass Spectrometry

    SciTech Connect

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

    2011-06-16

    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.

  2. Novel light sources using micro field emitters

    NASA Astrophysics Data System (ADS)

    Mimura, H.; Neo, Y.; Aoki, T.

    2008-05-01

    The paper describes the applications of micro- or nano-field emitters to a novel and compact light source. We have developed a compact pulse x-ray tube and demonstrated high-speed x-ray radiography images. We have also developed the electron-beam pumped ultraviolet (UV) light source consisting of a field emitter and a Si electron transparent film. This light source clearly showed a light emission due to Xe excimers in a vacuum UV region. In addition to them, we have successfully demonstrated Smith-Purcell radiation using a field emitter in a near infrared region.

  3. Design of fiber optic relayed laser radar

    NASA Astrophysics Data System (ADS)

    Tilleman, Michael M.; Krishnaswami, Kannan

    1996-11-01

    We have designed a new ladar (laser radar) for the detection of objects off the line of sight. The ladar operates by transmitting a signal through free space into a fiber optic relay, and receiving the returning signal from an obstacle. The transmitted signal is a laser diode emitting at 1550 nm, ideal from the aspects of eye safety and minimum loss in a silica fiber. Its immediate application is in railroad- transportation safety, where it detects obstacles present on the track with a very high probability of detection and a very low probability of false alarm.

  4. Radar frequency radiation

    NASA Astrophysics Data System (ADS)

    Malowicki, E.

    1981-11-01

    A method is presented for the determination of radar frequency radiation power densities that the PAVE PAWS radar system could produce in its air and ground environment. The effort was prompted by the concern of the people in the vicinity of OTIS AFB MA and BEALE AFB CA about the possible radar frequency radiation hazard of the PAVE PAWS radar. The method is based on the following main assumptions that: (a) the total field can be computed as the vector summation of the individual fields due to each antenna element; (b) the individual field can be calculated using distances for which the field point is in the far field of the antenna element. An RFR computer program was coded for the RADC HE 6180 digital computer and exercised to calculate the radiation levels in the air and ground space for the present baseline and the possible Six DB and 10 DB growth systems of the PAVE PAWS radar system at OTIS AFB MA. The average radiation levels due to the surveillance fence were computed for three regions: in the air space in front of the radar, at the radar hazard fence at OTIS AFB MA and at representative ground points in the OTIS AFB vicinity. It was concluded that the radar frequency radiation of PAVE PAWS does not present a hazard to personnel provided there is no entry to the air hazard zone or to the area within the hazard fence. The method developed offers a cost effective way to determine radiation levels from a phased array radar especially in the near field and transition regions.

  5. Staggered Costas signals

    NASA Astrophysics Data System (ADS)

    Freedman, Avraham; Levanon, Nadav

    1986-11-01

    A radar signal, based on coherent processing of a train of staggered Costas (1984) bursts is based on a minimum number of collocation of their individual ambiguity function sidelobe peaks. The resulting ambiguity function combines qualities of both 'thumbtack' and 'bed of nails' signals. Comparison with linear-FM, V-FM, and complementary phase coded signals is given, as well as comparison with hybrid signals consisting of both phase and frequency coding.

  6. Spaceborne laser radar.

    PubMed

    Flom, T

    1972-02-01

    Laser radar systems are being developed to acquire and track targets in applications such as the rendezvous and docking of two spacecraft. To search effectively for and locate a target using a narrow laser beam, a scanning system is needed. This paper describes a scan technique whereby a narrow laser beam is synchronously scanned with an equally narrow receiver field-of-view without the aid of mechanical gimbals. Equations are developed in order to examine the maximum acquisition and tracking rates, and the maximum target range for a scanning laser radar system. A recently built prototype of a small, lightweight, low-power-consuming scanning laser radar is described. PMID:20111497

  7. Radar transmitter procedures

    NASA Astrophysics Data System (ADS)

    1993-03-01

    This ITOP outlines the test methods used in evaluating the performance and characteristics of general types of radar transmitters to include single or variable frequency transmitters. The test methods serve as a guide in determining the overall efficiency of such equipment as a function of their design and their recorded performance. This ITOP is limited to methods for measuring the performance of the radar transmitter under test as a major component. Some performance aspects of the transmitter can be tested only when configured as part of a total radar system.

  8. Some effects of range upon AN/CPS-9 radar reflectivities in thunderstorms 

    E-print Network

    Sanford, Tom E

    1961-01-01

    the radar signal beam was at such an angle that it passed above all storms within range of and detectable by the radar set. Echoes at ranges of less than 30 mi and greater than 200 mi were not considered in this study. The radar photographs were projected... on a Richardson film viewer for easy analysis, and the elevation angles and receiver gain steps for the minimum received signal were recorded and punched on IBM punch cards. Computations of radar reflectivity factors and heights were performed...

  9. Radar ECCM's new area: Anti-STEALTH and anti-ARM

    NASA Astrophysics Data System (ADS)

    Li, Nengjing

    1987-07-01

    While stealth and anti-radar missiles will become major threats to military radars, many countermeasures are also being developed. The commonly used countermeasures against these two threats are: the use of bistatic (or multistatic) systems and low carrier frequencies. Some techniques are also effective against electronic jamming, e.g., low probability intercept techniques (including super-low sidelobe antenna, frequency hopping, flexible and variable coded signals), bistatic (multistatic) systems, weak signal detection and high radar mobility. Clearly, these techniques should be the focal point for current radar research.

  10. Digitized dual wavelength radar data from a Texas thunderstorm 

    E-print Network

    Radlein, Robin Ann

    1977-01-01

    ) Antenna beam width~8(horizontal) ](vertical) 0 ' 5 5 1 54 1 54 0 5 5 1 54 1 ~ 52 Antenna Gain, G~ db Minimum detectable signal, dhm 2 3 -6 Radar Constant, C, w km m mm 40 5 -107 5 1 0089%10 40 3 -107 5 8, 609%10 13 radar beam... of the most important tools for the detection of severe local storms such as tornadoes~ hailstorms~ and severe thunderstorms The usefulness of early radars was limited~ however, by the capacity of the operator to recognize the type and severity of a storm...

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

    PubMed Central

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

    2009-01-01

    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

  12. Electrospray emitters For diffusion vacuum pumps

    E-print Network

    Diaz Gómez Maqueo, Pablo (Pablo Ly)

    2011-01-01

    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 ...

  13. Emitters of N-photon bundles

    PubMed Central

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

    2014-01-01

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

  14. SAR raw signal simulation for urban structures

    Microsoft Academic Search

    Giorgio Franceschetti; Antonio Iodice; Daniele Riccio; Giuseppe Ruello

    2003-01-01

    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

  15. Shared-spectrum multistatic radar: Preliminary experimental results

    Microsoft Academic Search

    Aaron K. Shackelford; Jean de Graaf; S. Talapatra; K. Gerlach; S. D. Blunt

    2007-01-01

    In this paper we present preliminary experimental results demonstrating the ability of the multistatic adaptive pulse compression (MAPC) algorithm to suppress the mutual-interference generated by shared-spectrum radar signals, thus enabling shared-spectrum radar. The MAPC algorithm, a waveform diversity technique wherein multiple known transmitted waveforms are adaptively pulse compressed using reiterative minimum mean-square error (RMMSE) estimation, has been shown to successfully

  16. Range-dependence Issues in Multistatic STAP-based Radar

    Microsoft Academic Search

    Xavier Neyt; Marc Acheroy; Jacques G. Verly

    2006-01-01

    Multisatic radar systems offer the potential to overcome some of the limitations of the monostatic or bistatic systems. In particular, the ability to build larger apertures allows to increase spatial accuracy. Space-time adaptive processing (STAP) is a method of choice in the context of slow-moving target detection. However, the statistics of signals from multistatic radars are typically range-dependent. This range-dependence

  17. Reconfigurable data acquisition system for weather radar applications

    Microsoft Academic Search

    Rishi Khasgiwale; Luko Krnan; Atchuthan Perinkulam; Russell Tessier

    2005-01-01

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

  18. Radar image processing module development program, phase 3

    NASA Technical Reports Server (NTRS)

    1977-01-01

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

  19. Emitter Wrap-Through solar cell

    SciTech Connect

    Gee, J.M.; Schubert, W.K.; Basore, P.A.

    1992-01-01

    The authors present a new 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 EWT cells, respectively.

  20. Emission current formation in plasma electron emitters

    SciTech Connect

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

    2010-12-15

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

  1. Energy efficiency of electron plasma emitters

    SciTech Connect

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

    2011-12-15

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

  2. Reducing RFQ output emittance by external bunching

    SciTech Connect

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

    1994-05-01

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

  3. Coaxial inverted geometry transistor having buried emitter

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

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

  4. Normalized emittance of SITEX negative ion source

    SciTech Connect

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

    1983-01-01

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

  5. Emittance measurement in a magnetic field

    SciTech Connect

    Boyd, J.K.

    1991-04-15

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

  6. Two decades of array signal processing research: the parametric approach

    Microsoft Academic Search

    H. Krim; M. Viberg

    1996-01-01

    The quintessential goal of sensor array signal processing is the estimation of parameters by fusing temporal and spatial information, captured via sampling a wavefield with a set of judiciously placed antenna sensors. The wavefield is assumed to be generated by a finite number of emitters, and contains information about signal parameters characterizing the emitters. A review of the area of

  7. Phase noise effects on turbulent weather radar spectrum parameter estimation

    Microsoft Academic Search

    Jonggil Lee; Ernest G. Baxa

    1990-01-01

    Accurate weather spectrum moment estimation is important in the use of weather radar for hazardous windshear detection. The effect of the stable local oscillator (STALO) instability (jitter) on the spectrum moment estimation algorithm is investigated. Uncertainty in the stable local oscillator will affect both the transmitted signal and the received signal since the STALO provides transmitted and reference carriers. The

  8. Directional borehole radar with dipole antenna array using optical modulators

    Microsoft Academic Search

    Satoshi Ebihara

    2004-01-01

    In this paper, we describe a directional borehole radar comprising a dipole antenna array with an optical modulator capable of determining the position of targets in three dimensions (3-D). Optical modulators using a Mach-Zehnder interferometer are used to transform electrical signals into optical signals at the feeding points of the dipole antennas. The advantages of using these modulators are that

  9. Radar - The Future

    NASA Astrophysics Data System (ADS)

    Warwick, G.

    1985-02-01

    Progress in civil and military radar units since the invention of radar in 1935 is summarized, noting the trend to multipurpose units. The earliest systems functioned at 10 cm, then 3 cm after development of a cavity magnetron to provide power for shorter wavelengths. Military needs are driving improvements in three-dimensional scanning capabilities, Primarily to locate aircraft in the presence of ground clutter and sea surface scattering. Autonomous, separate transmitter and receiver units are being tested. Lengthening ground-based radar wavelengths to tens of meters will permit over-the-horizon sensing with backscattering, ionospheric bounce, or induction of a potential in the sea surface as the possible techniques. Mode S monopulse radars will permit transponder queries between small and large aircraft. Finally, pulse Doppler SAR systems may afford terrain recognition with no corroborating data except an expert systems data base.

  10. Caribbean Radar Products

    NSDL National Science Digital Library

    2014-09-14

    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.

  11. Millimeter Waves Ballistic Radar

    Microsoft Academic Search

    A. N. Zubkov; V. S. Gavrilov; Ya. M. Kempa; Z. V. Dufanets; N. A. Naumets

    2006-01-01

    Solid-state Doppler millimeter waves ballistic radar designed for measuring of exterior and interior ballistic parameters of highly dynamical faint objects is developed. The coherence characteristics of transmit-receive module are supported by the floating heterodyne oscillation behavior

  12. Measurement of Distance down to Zero Meters by Standing Wave Radar

    NASA Astrophysics Data System (ADS)

    Uebo, Tetsuji

    Various types of radars have been developed and used until now—such as Pulse, FM-CW, and Spread Spectrum. Additionally, another type of radar has been proposed recently. The radar measures distance by using standing wave and has been named as “Standing Wave Radar." Standing wave radar has a shorter minimum detectable range and higher accuracy compared to other types. However, the radar can not measure distance down to zero meters like other types of radars. Minimum detectable range of the standing wave radar depends on a usable frequency range. A wider frequency range is required if we need to measure shorter distance. We show a new method for measuring distance down to zero meters without expanding the frequency range. Specifically, we derive an analytic signal, which is a complex sinusoidal signal, by processing the signals obtained from multiple detectors, and we calculate and obtain distances by Fourier transform of the analytic signal. We then verify the validity of our method by simulations based on numerical calculation. The results show that it is possible to measure distance down to zero meters. In our method, measurement errors are caused by gain deviation of the detectors. They are several cm if the gain deviations are less than ±1%. Prevalent radars still have a common defect that they can not measure distance from zero to the minimum detectable range. We expect that the defect will be eliminated by putting our method into practical use.

  13. Cassini Radar hardware technologies

    SciTech Connect

    Wheeler, K.; Renick, P. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States)

    1996-03-01

    The hardware development portion of the Cassini Radar task is complete. The flight model Digital Assembly and Energy Storage Assembly have been integrated and tested, as has the engineering/qualification model Radio Frequency Electronics Assembly. Integration of the flight model Radio Frequency Electronics Assembly is ready to begin. The intent of this paper is to describe some of the more interesting technologies implemented in the electronics to achieve the requirements of the Cassini Radar experiment. {copyright} {ital 1996 American Institute of Physics.}

  14. Phased-array radars

    NASA Astrophysics Data System (ADS)

    Brookner, E.

    1985-02-01

    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.

  15. Multiresolution GMTI radar

    Microsoft Academic Search

    J. R. Guerci; A. O. Steinhardt

    2003-01-01

    The detection and tracking of ground moving vehicles from airborne radar can be challenging at slow target velocities due to the close space-time (angle-Doppler) proximity of strong competing mainbeam clutter. Moreover, in complex non-stationary clutter environments, conventional space-time adaptive processing (STAP) cannot be relied upon to provide precision ing. In this paper, we re-examine GMTI radar from a multiresolution perspective

  16. Weather Radar Network Design

    Microsoft Academic Search

    Francesc Junyent; V. Chandrasekar

    2008-01-01

    The Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) is investigating the use of dense networks of short-range radars for weather sensing. A first test-bed of this new paradigm is currently deployed in southwest Oklahoma. The potential benefits of closely deployed, overlapping, short-range weather radars are easy to see intuitively amounting to a greater ability to measure

  17. Doppler Radar Technology

    NSDL National Science Digital Library

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

  18. Radar network characterization

    Microsoft Academic Search

    Francesc Junyent; V. Chandrasekar

    2007-01-01

    The use of dense networks of small radars for weather sensing is being investigated by the Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere, with a first test-bed of this new paradigm well underway. The potential benefits of closely-deployed, overlapping, short-range weather radars are easy to see intuitively, and can be summarized as a greater ability to mitigate

  19. Some non-precipitation radar echoes as observed by CPS-9 radar 

    E-print Network

    Luckenbach, Guenther Edward

    1959-01-01

    10 3 1 degree Beam width (horizontal) 1 degree Pulse Length short (0. 5 p sec*) 150 m long (5. 0 p sec ) 1, 500 m p (min) r Wave Length Minimum detectable signal 3. 2 cm short pulse 1. 6 x 10 watt -13 long pulse 1. 6 x 10 watt The variable... will be a challenge to researchers to investigate in detail each of the echo types. I ortance of the Stud The detection of precipitation radar echoes has long been accepted as the dominant observation in radar meteorological practices. The high...

  20. An update on the multi-channel phased array Weather Radar at the National Weather Radar Testbed

    Microsoft Academic Search

    M. Yeary; G. Crain; A. Zahrai; R. Kelley; J. Meier; Y. Zhang; I. Ivic; C. Curtis; R. Palmer; T.-Y. Yu; R. Doviak

    2011-01-01

    The first phased array radar dedicated to weather observation and analysis is now instrumented with eight, simultaneous digital receivers. The multi-channel receiver will collect signals from the sum, azimuth-difference, elevation- difference, and five broad-beamed auxiliary channels. The multi-channel receiver will allow the direct implementation of interferometry techniques to estimate crossbeam wind, shear and turbulence within a radar resolution volume. Access

  1. Ultrawideband imaging radar based on OFDM: system simulation analysis

    NASA Astrophysics Data System (ADS)

    Garmatyuk, Dmitriy

    2006-05-01

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

  2. A chip-scale, telecommunications-band frequency conversion interface for quantum emitters

    E-print Network

    Agha, Imad; Davanco, Marcelo; Srinivasan, Kartik

    2013-01-01

    We describe a chip-scale frequency conversion interface designed for connecting photons generated by single quantum emitters to the 1550 nm telecommunications band. Four-wave-mixing Bragg scattering in silicon nitride waveguides is used to demonstrate frequency upconversion and downconversion between the 980 nm and 1550 nm wavelength regions, with signal-to-background levels > 10. Finite element simulations and the split-step Fourier method are used to develop waveguide designs that can connect shorter wavelength (637 nm to 852 nm) quantum emitters with 1550 nm. Finally, the conditions for achieving the conversion efficiencies needed for practical demonstrations of frequency conversion of quantum states of light are discussed.

  3. Radar Observations of Asteroid 2063 Bacchus

    Microsoft Academic Search

    Lance A. M. Benner; R. Scott Hudson; Steven J. Ostro; Keith D. Rosema; Jon D. Giorgini; Donald K. Yeomans; Raymond F. Jurgens; David L. Mitchell; Ron Winkler; Randy Rose; Martin A. Slade; Michael L. Thomas; Petr Pravec

    1999-01-01

    We report Doppler-only (cw) and delay-Doppler radar observations of Bacchus obtained at Goldstone at a transmitter frequency of 8510 MHz (3.5 cm) on 1996 March 22, 24, and 29. Weighted, optimally filtered sums of cw and delay-Doppler echoes achieve signal-to-noise ratios of ?80 and ?25, respectively, and cover about 180° of rotation phase (period=14.90 h; Pravec et al. 1998). Our

  4. Overview of detection theory in multistatic radar

    Microsoft Academic Search

    E. Daddio; A. Farina

    1986-01-01

    The detection problem with multistatic radar systems is considered, resorting to the theory of detection of coherent target signals having a Gaussian probability density embedded in coherent Gaussian-distributed disturbances (i.e. clutter and\\/or directional jamming). A novelty of the paper is related to the capability of dealing with any type of time autocorrelation function of both target and disturbance. The spatial

  5. SOURCESCAT - A very fine resolution radar scatterometer

    Microsoft Academic Search

    R. Zoughi; L. K. Wu; R. K. Moore

    1985-01-01

    A short-range, high resolution FM-CW radar system has been used to investigate the sources of backscatter in various types of crops, trees, surfaces and man-made targets. A transmitted signal bandwidth of 2.0 GHz at 10.0 GHz center frequency provides a range resolution of 11 cm. A focused parabolic antenna, providing narrow effective antenna beamwidths in both the azimuth and the

  6. Distributed aperture radar using small satellites

    Microsoft Academic Search

    Ken Molz

    1989-01-01

    Recent work on key technological problems of self-cohering and high-speed processing has led to a concept for distributed space based radar. Experimentally demonstrated self-cohering techniques allow a cluster of small satellites to form a coherent aperture even though the position of each satellite in the cluster is not precisely known. The signal processing of the receive beams has been sized,

  7. Progress in coherent laser radar

    NASA Technical Reports Server (NTRS)

    Vaughan, J. M.

    1986-01-01

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

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

    E-print Network

    Rutledge, Steven

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

  9. A FMCW Radar Acquisition and Process System Based on LabVIEW

    Microsoft Academic Search

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

    2009-01-01

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

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

    Microsoft Academic Search

    Miguel Angel Rico-Ramirez; Ian David Cluckie

    2008-01-01

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

  11. Radar Range Sidelobe Reduction Using Adaptive Pulse Compression Technique

    NASA Technical Reports Server (NTRS)

    Li, Lihua; Coon, Michael; McLinden, Matthew

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  13. Weather Radar and Instrumentation: Laboratory Modules

    NSDL National Science Digital Library

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

  14. Radar Observations of Asteroid 7822 (1991 CS)

    NASA Astrophysics Data System (ADS)

    Benner, Lance A. M.; Ostro, Steven J.; Rosema, Keith D.; Giorgini, Jon D.; Choate, Dennis; Jurgens, Raymond F.; Rose, Randy; Slade, Martin A.; Thomas, Michael L.; Winkler, Ron; Yeomans, Donald K.

    1999-02-01

    We report Doppler-only (cw) radar observations of near-Earth asteroid 1991 CS obtained at Goldstone at a transmitter frequency of 8510 MHz (3.5 cm) on 1996 August 26, 27, 28, and 29. Weighted, optimally filtered sums of cw echoes achieve signal-to-noise ratios in excess of 300 per day and thoroughly cover the asteroid in rotation phase (synodic period=2.39 h, obtained photometrically by P. Pravecet al.1998,Icarus136, 124-153). A weighted sum of all cw spectra gives an OC radar cross section of 0.24±0.08 km2and a circular polarization ratio of 0.28±0.001. Our observations place up to 50 0.98-Hz resolution cells on 1991 CS at echo powers greater than 2 standard deviations of the noise. Variations of ?10 Hz in the echo's 2-? bandwidth are evident on each day and are consistent with the rotation period. Inversion of echo edge frequencies yields convex hulls of the pole-on silhouette for each day. The hulls have a mean elongation and rms dispersion of 1.18±0.02 and place a lower bound on the maximum pole-on dimension of 1.3 km/cos?, where ? is the angle between the radar line-of-sight and the asteroid's apparent equator. The hulls suggest that 1991 CS has the least elongated pole-on silhouette of any of the nine near-Earth asteroids for which similar shape information from radar observations is available. If we assume that the projected area of 1991 CS is the same as that of a sphere with a diameter of 1.1 km, equal to the lower bound on the minimum breadth of the pole-on silhouette on August 28 and 29, then 1991 CS's radar cross section and absolute magnitude of 17.5 correspond to upper limits on the radar and optical geometric albedos of 0.25 and 0.14 that are consistent with its S-class taxonomy. The circular polarization ratio and radar albedo do not vary substantially as a function of rotation phase, suggesting that the near-surface of 1991 CS is relatively uniform. Among the 20 S-class asteroid radar detections previously reported, the circular polarization ratio of 1991 CS is greater than 11, comparable to 4, and less than 5.

  15. Radar observations of asteroid 7822 (1991 CS)

    NASA Astrophysics Data System (ADS)

    Benner, L. A. M.; Ostro, S. J.; Rosema, K. D.; Giorgini, J. D.; Choate, D.; Jurgens, R. F.; Rose, R.; Slade, M. A.; Thomas, M. L.; Winkler, R.; Yeomans, D. K.

    1998-09-01

    We report Doppler-only (cw) radar observations of 1991 CS obtained at Goldstone at a transmitter frequency of 8510 MHz (3.5 cm) on 1996 August 26, 27, 28, and 29. Weighted, optimally filtered sums of cw echoes achieve signal-to-noise ratios in excess of 300 per day that thoroughly cover the asteroid in rotation phase (synodic period = 2.39 h, obtained photometrically by Pravec et al., submitted). A weighted sum of all cw spectra gives an OC radar cross section of 0.24+/-0.08 km(2) and a circular polarization ratio of 0.28+/-0.001. Our observations place up to fifty 0.98-Hz resolution cells on 1991 CS at echo powers greater than two standard deviations of the noise. Variations of 10 Hz in the echo's 2-sigma bandwidth are evident on each day and are consistent with the rotation period. Inversion of echo edge frequencies yields convex hulls of the pole-on silhouette for each day. The hulls have a mean elongation and rms dispersion of 1.18+/-0.02 and place a lower bound on the maximum pole-on dimension of 1.3 km/cos(delta), where delta is the angle between the radar line-of-sight and the asteroid's pole direction (which is unknown). The hulls suggest that 1991 CS has the least elongated pole-on silhouette of any of the eight near-Earth asteroids for which similar shape information from radar observations is available. If we assume that the projected area of 1991 CS is the same as that of a sphere with a diameter of 1.1 km, equal to the lower bound on the minimum breadth of the pole-on silhouette on August 28 and 29, then 1991 CS' radar cross section and absolute magnitude of 17.5 correspond to upper limits on the radar and optical geometric albedos of 0.25 and 0.14 that are consistent with its S-class taxonomy. The circular polarization ratio and radar albedo do not vary substantially as a function of rotation phase, suggesting that the near-surface of 1991 CS is relatively uniform. Among the twenty S-class asteroid radar detections previously reported, the circular polarization ratio of 1991 CS is greater than eleven, comparable to four, and less than five.

  16. A fully photonics-based coherent radar system.

    PubMed

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

    2014-03-20

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

  17. Optical signal processing

    NASA Technical Reports Server (NTRS)

    Casasent, D.

    1978-01-01

    The article discusses several optical configurations used for signal processing. Electronic-to-optical transducers are outlined, noting fixed window transducers and moving window acousto-optic transducers. Folded spectrum techniques are considered, with reference to wideband RF signal analysis, fetal electroencephalogram analysis, engine vibration analysis, signal buried in noise, and spatial filtering. Various methods for radar signal processing are described, such as phased-array antennas, the optical processing of phased-array data, pulsed Doppler and FM radar systems, a multichannel one-dimensional optical correlator, correlations with long coded waveforms, and Doppler signal processing. Means for noncoherent optical signal processing are noted, including an optical correlator for speech recognition and a noncoherent optical correlator.

  18. Power centroid radar and its rise from the universal cybernetics duality

    NASA Astrophysics Data System (ADS)

    Feria, Erlan H.

    2014-05-01

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

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

    Microsoft Academic Search

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

    2004-01-01

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

  20. SRTM Radar - Landsat Image Comparison, Patagonia, Argentina

    NASA Technical Reports Server (NTRS)

    2000-01-01

    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)

  1. RADAR: THE CASSINI TITAN RADAR MAPPER C. ELACHI1,

    E-print Network

    RADAR: THE CASSINI TITAN RADAR MAPPER C. ELACHI1, , M. D. ALLISON2 , L. BORGARELLI3 , P. ENCRENAZ4; Accepted in final form 3 June 1999) Abstract. The Cassini RADAR instrument is a multimode 13.8 GHz multiple coefficient as low as -40 dB. 1. Introduction The Cassini spacecraft, launched on October 15, 1997, carries

  2. Minimum radar cross section bounds for passive radar responsive tags

    Microsoft Academic Search

    P. Bidigare; T. Stevens; B Correll; M. Beauvais

    2004-01-01

    A common problem in ground moving target indication (GMTI) radar is detecting a target with even a large radar cross section (RCS) when its line-of-sight velocity falls below the minimum detectable velocity (MDV) for that radar system. In a cooperative scenario, a target may employ a tagging device, which can shift or spread its Doppler signature to become more detectable.

  3. The "Radar-Progress" active space experiment

    NASA Astrophysics Data System (ADS)

    Khakhinov, Vitaly; Mikhalev, Alexander; Potekhin, Alexander; Alsatkin, Sergey; Podlesnyi, Alexey; Beletsky, Alexandr; Klunko, Evgeny; Tverdokhlebova, Ekaterina; Timofeeva, Nataliya; Lebedev, Valentin; Kushnarev, Dmitrii; Kurshakov, Mikhail; Manzheley, Andrey

    Central Research Institute of Machine Building and Institute of Solar-Terrestrial Physics Siberian Branch of Russian Academy of Sciences have carried out the "Radar-Progress" active space experiment since 2006. After main mission, some of the “Progress” cargo vehicles have been for the experiment. The “Progress” starts orbital maneuvering subsystem engines during the flyby over Irkutsk Incoherent Scatter Radar at 340 - 410 km altitude. Engines operate for 5 - 11 s. Engines exhaust products are a source of ionosphere disturbances. The flow directions and amount of injected exhaust products varied from flight to flight. The flows directed to Irkutsk Radar are almost parallel to the geomagnetic field lines. The following measurements have been performed: - radar characteristics; - height profiles of electron density; - spatial-temporal structure of ionosphere disturbances; - intensity of nightglow emissions in several spectral lines; - onboard VHF transmitter signal parameters; - brightness of the “Progress” in optical ranges; - geomagnetic field variations. These results were obtained with unique research facilities of Center for collective using "Angara". The study has been supported by the grant 13-05-00456-a and 13-02-00957-a of the Russian Foundation for Basic Research.

  4. Space Charge Suppression for Uneven Emittances

    SciTech Connect

    Burov, A.; Derbenev, Ya.; /Fermilab /JLAB Newport News

    2009-01-01

    The intensity of low and intermediate energy accelerators and storage rings is limited by space charge effects. An increase of the space charge tune shift may lead to lifetime degradation and coherent instability. A method to suppress the space charge effect is suggested for a beam with two uneven emittances. It has been shown that for a beam with uneven emittances, use of the circular optics makes the space charge tune shift equal to its planar value in the large-emittance direction. This removes a limit on the smaller emittance from the space charge side. Thus, since flat beams can be extremely bright, they could find their use in various applications: ion-electron colliders, nuclear fusion, medicine, and others. One additional possibility for the use of these beams relates to the fact that in a matched solenoid the CAM-dominated beam is transformed into a parallel beam. This transformation is essential for relativistic electron cooling of antiprotons at Fermilab. The two transverse emittances can be made significantly different either by means of a special injection procedure (painting), or by cooling, or by extraction of the beam from a magnetized gun. In any case, use of the circular optics appears to open a special possibility for extremely bright beams.

  5. Current limiting of field emitter array cathodes

    SciTech Connect

    Lee, K.J.

    1986-01-01

    The Field Emitter Array (FEA) cathode possesses high emission potential (approx.30A/cm/sup 2/) at low applied voltages (100-200 volts) but performance has been hampered by non-uniform emission across the array. Poor emission uniformity is mainly related to small variations in emitter tip geometry (of the order of 10-100A), which cannot be rectified by present fabrication techniques. To improve emission uniformity from the arrays, this dissertation investigated the use of current-limiting resistors, individually dedicated to and in series with each emitter, to compensate for the differences in emission. A thin film of silicon was deposited on the backside of a ZrO/sub 2/-W composite chip (the substrate on which emitter structure was based) to form series resistors. Characterization of the silicon film was carried out in a SEM with a micromanipulator capable of making contact with a single tungsten pin so that direct I-V measurement of individual series resistors was possible. To supplement the experimental effort, a mathematical mode of the Current-Limited Field Emitter Array (CLFEA) cathode was devised. A study of the model indicated the Fowler-Nordheim (F-N) plot of resistor current-limited emission from an array would have an upturning curvature.

  6. Enhanced angular current intensity from Schottky emitters.

    PubMed

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

    2010-09-01

    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

  7. ETAII 6 MEV PEPPERPOT EMITTANCE MEASUREMENT

    SciTech Connect

    Paul, A C; Richardson, R; Weir, J

    2004-10-18

    We measured the beam emittance at the ETAII accelerator using a pepper-pot diagnostic at nominal parameters of 6 MeV and 2000 Amperes. During the coarse of these experiments, a ''new tune'' was introduced which significantly improved the beam quality. The source of a background pedestal was investigated and eliminated. The measured ''new tune'' emittance is {var_epsilon}= 8.05 {plus_minus} 0. 53 cm - mr or a normalized emittance of {var_epsilon}{sub n} = 943 {plus_minus} 63 mm - mr In 1990 the ETAII programmatic emphasis was on free electron lasers and the paramount parameter was whole beam brightness. The published brightness for ETAII after its first major rebuild was J = 1 - 3 x 10{sup 8} A/(m - rad){sup 2} at a current and energy of 1000-1400 Amperes and 2.5 MeV. The average normalized emittance derived from table 2 of that report is 864 mm-mr corresponding to a real emittance of 14.8 cm-mr.

  8. Microwave emissions from police radar 

    E-print Network

    Fink, John Michael

    1994-01-01

    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...

  9. Venus wind-altitude radar

    NASA Technical Reports Server (NTRS)

    Levanon, N.

    1974-01-01

    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.

  10. Systems and Methods for Radar Data Communication

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

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

    SciTech Connect

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

    2006-11-20

    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.

  12. Noise Considerations in Self-Mixing IMPATT-Diode Oscillators for Short-Range Doppler RADAR Applications

    Microsoft Academic Search

    M.-S. Gupta; R. J. Lomax; G. I. Haddad

    1974-01-01

    The influence of the oscillator noise on the minimum detectable signal of a Doppler RADAR with a self-mixing IMPATT-diode oscillator is evaluated. For very short-range RADARs, it is the AM noise which limits the signal-to-noise ratio and thus the range.

  13. A review of array radars

    Microsoft Academic Search

    E. Brookner

    1981-01-01

    Achievements in the area of array radars are illustrated by such activities as the operational deployment of the large high-power, high-range-resolution Cobra Dane; the operational deployment of two all-solid-state high-power, large UHF Pave Paws radars; and the development of the SAM multifunction Patriot radar. This paper reviews the following topics: array radars steered in azimuth and elevation by phase shifting

  14. Radar sector blanker

    NASA Astrophysics Data System (ADS)

    Hall, Roger B.

    1994-03-01

    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.

  15. Head erosion with emittance growth in PWFA

    SciTech Connect

    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

    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.

  16. Parallel signal processing

    NASA Astrophysics Data System (ADS)

    McWhirter, John G.

    1989-12-01

    The potential application of parallel computing techniques to digital signal processing for radar is discussed and two types of regular array processor are discussed. The first type of processor is the systolic or wavefront processor. The application of this type of processor to adaptive beamforming is discussed and the joint STL-RSRE adaptive antenna processor test-bed is reviewed. The second type of regular array processor is the SIMD parallel computer. One such processor, the Mil-DAP, is described, and its application to a varied range of radar signal processing tasks is discussed.

  17. The Clementine Bistatic Radar Experiment

    Microsoft Academic Search

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

    1996-01-01

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

  18. The Shuttle Radar Topography Mission

    Microsoft Academic Search

    Tom G. Farr; Paul A. Rosen; Edward Caro; Robert Crippen; Riley Duren; Scott Hensley; Michael Kobrick; Mimi Paller; Ernesto Rodriguez; Ladislav Roth; David Seal; Scott Shaffer; Joanne Shimada; Jeffrey Umland; Marian Werner; Michael Oskin; Douglas Burbank; Douglas Alsdorf

    2007-01-01

    The Shuttle Radar Topography Mission produced the most complete, highest-resolution digital elevation model of the Earth. The project was a joint endeavor of NASA, the National Geospatial-Intelligence Agency, and the German and Italian Space Agencies and flew in February 2000. It used dual radar antennas to acquire interferometric radar data, processed to digital topographic data at 1 arc sec resolution.

  19. SEASAT Synthetic Aperture Radar Data

    NASA Technical Reports Server (NTRS)

    Henderson, F. M.

    1981-01-01

    The potential of radar imagery from space altitudes is discussed and the advantages of radar over passive sensor systems are outlined. Specific reference is made to the SEASAT synthetic aperture radar. Possible applications include oil spill monitoring, snow and ice reconnaissance, mineral exploration, and monitoring phenomena in the urban environment.

  20. Review of current radar interests

    Microsoft Academic Search

    M. I. Skolnik

    1974-01-01

    Current radar applications and problem areas are reviewed. Air traffic control, aircraft and ship navigation, remote sensing, and law enforcement are some of the applications mentioned. Both the Gemini and the Apollo space vehicles used radar for rendezvous and docking, and Apollo also utilized it for lunar landing. Equipment improvements suggested include better isolation in CW radar, efficient linear transmitters,