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29th Asilomar Conference on Signals, Systems and computers, ACSSC 1995

作者： Goldstein, J. Scott Kogon, Stephen M. Reed, Irving S. Williams, Douglas B. Holder, E. Jeff USAF Rome Laboratory RL/C3BA 525 Brooks Rd. Grifilss AFBNY13441-4505 United States Statistical Signal and Image Processing Laboratory Department of Electrical Engineering University of Southern California Los AngelesCA90089-2565 United States Digital Signal Processing Laboratory School of Electrical and Computer Engineering Georgia Institute of Technology AtlantaGA30332-0250 United States

ISBN: (纸本)0818673702

This paper is concerned with reducing the rank of the adaptive weight vector in radar array signal processing. The motivation for reducing the rank is that modern space-time processing requires many more weights than can be supported on airborne and spacesegment platforms. The loss incurred in partially adaptive radar processing is that the steady-state Wiener solution of the lower rank weight vector may not perform as well as the full rank solution. Hence, this paper will be concerned with the Wiener solution of partially adaptive radar arrays and compare the performance of principal component techniques with the recently developed crossspectral technique. © 1996 IEEE.

关键词： Array processing

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The tail of sea-surface radar backscatter distribution and its dependence on the long waves

The tail of sea-surface radar backscatter distribution and i...

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IEEE International Symposium on Geoscience and remote sensing (IGARSS)

作者： S. Haimov R.K. Moore Radar Systems and Remote Sensing Laboratory Department of Electrical Engineering and Computer Science University of Kansas Lawrence KS USA

A technique for studying radar sea backscatter modulation and non-Bragg scattering is developed. It is based on simultaneous measurements of the radar backscattered field and the surface elevation from the same location on the sea surface. Instantaneous ocean wave frequencies are determined from the surface elevation using a parametric auto-regressive (AR) model. They are used to calculate the average received power and the radar power distribution tail contribution (sea spikes) with respect to the phase of the long (12- to 150-m) ocean waves. The analysis shows that sea spikes are the result of different non-linear phenomena and are present at every wave location, not only at the crest.

关键词： Probability distribution Backscatter Sea surface Radar scattering Ocean waves Sea measurements Radar measurements Frequency Surface waves Power distribution

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MMIC-based FM-CW radar for multipolarization backscatter measurements

MMIC-based FM-CW radar for multipolarization backscatter mea...

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IEEE International Symposium on Geoscience and remote sensing (IGARSS)

作者： G. Prescott S. Gogineni D. Depardo H. Chakravarthula R. Hosseinmostafa Radar Systems and Remote Sensing Laboratory Department of Electrical Engineering and Computer Science University of Kansas Lawrence KS USA

Presents a compact multipolarization radar that is designed around a new FM-CW microwave monolithic integrated circuit (MMIC). The FM-CW MMIC device consists of a varactor-tuned oscillator, an amplifier, an active circulator and a mixer. The radar is designed to transmit either a vertically or horizontally polarized signal and to receive both co- and cross-polarized signals simultaneously. The MMIC device is integrated with an external receiver and GaAs transfer switch to obtain all four linear polarizations. The cross-polarization receiver was assembled using a GaAs MMIC mixer and amplifier. The signal processor is a standard commercially available digital signal processing (DSP) board, which is connected to the bus of a personal computer. The radar and signal processor were developed by undergraduate students enrolled in a one-semester senior design course. The total cost of the radar, including the DSP board, was less than $10,000.

关键词： Radar Backscatter MMICs Digital signal processing Signal design Polarization Gallium arsenide Switches Signal processing Microwave devices

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Alternate cutoff radius criterion for probe-fed, circular microstrip patches

Alternate cutoff radius criterion for probe-fed, circular mi...

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Antennas and Propagation Society International Symposium

作者： D. Chatterjee R.G. Plumb Radar Systems and Remote Sensing Laboratory Department of Electrical Engineering and Computer Science University of Kansas Lawrence KS USA

The effects of the patch size on probe-excited surface currents are relatively unknown. A simple yet rigorous criterion for selecting the cutoff radius of a circular microstrip patch is obtained from the contour integral representations of the infinite series terms of the probe-to-patch attachment mode current. This criterion predicts that by suitably selecting the patch dimensions and the substrate parameters, higher order terms may be suppressed. It is also shown that this criterion has remarkably similar features to earlier results, based on suppressing the lowest order TM/sub 01/ surface wave mode. Use of this result in optimizing patch radius for efficient feed and radiation performances is also suggested.

关键词： Surface waves Feeds Geometry Probes Radar remote sensing remote sensing Laboratories Microstrip antenna arrays Eigenvalues and eigenfunctions Clocks

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Ultra-wideband radar measurements over bare and snow-covered saline ice

Ultra-wideband radar measurements over bare and snow-covered...

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IEEE International Symposium on Geoscience and remote sensing (IGARSS)

作者： S. Gogineni K. Jezek Radar Systems and Remote Sensing Laboratory Department of Electrical Engineering and Computer Science University of Kansas Lawrence KS USA Byrd Polar Research Center Ohio State Uinversity Columbus OH USA

The authors developed an ultra-wideband radar operating over the frequencies from 2 to 18 GHz. They used this system in conjunction with a plane-wave illuminator to perform radar scattering measurements over bare and snow-covered saline ice. They made these measurements over saline ice grown in an outdoor pond at the U.S. Army Cold Regions Research and engineering laboratory, Hanover, NH. They collected radar data over incidence angles from 0/spl deg/ to 50/spl deg/ in conjunction with measurements of surface roughness, snow properties and ice structure. The combination of wide bandwidth and plane-wave illumination allowed them uniquely to identify returns from air-snow and snow-ice interfaces. They found that the snow-ice returns were at about 10 dB higher than those from the air-snow interface. The results also show that scattering from bare saline ice is dominated by ice surface at frequencies lower than about 10 GHz and incidence angles less than about 30/spl deg/. They also determined angular and spectral responses for smooth bare, snow-covered and pancake ice. For pancake ice the scattering coefficient at 30/spl deg/ increased from -22 at 2 GHz to about -10 at 15 GHz. Over incidence angles from 0/spl deg/ to 30/spl deg/ at 5.5 GHz, the scattering coefficient decreased by about 30 dB for pancake ice, and by about 45 dB for bare and snow-covered ice. They also compared data from laboratory observations with field measurement made during the International Arctic Ocean Experiment in 1991. For pancake ice the average scattering coefficient from laboratory observations is within 1 dB of field observations. This shows that simulation of pancake ice in the laboratory is successful.

关键词： Ultra wideband technology Radar measurements Radar scattering Sea measurements Laboratories Frequency Ice surface Performance evaluation Data engineering Rough surfaces

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MODELING BALUNS WITH THE METHOD OF MOMENTS

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IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 1994年第8期42卷 1195-1198页

作者： DEMAREST, K PLUMB, R HUANG, ZB Department of Electrical Engineering and Computer Science Radar Systems and Remote Sensing Laboratory University of Kansas Lawrence KS USA

When using the method of moments (MoM) to model large arrays with large numbers of balanced feeds, the feed baluns can always be incorporated into the analysis by combining the multiport admittance matrix for the array with the admittance matrices of the baluns. This technique is straightforward but requires that the MoM equations be solved for a large number of right-hand sides. This paper shows how the effects of perfect baluns can be incorporated directly into the MoM equations, requiring only one right-hand side. This technique yields the exact results with a significant savings in computing resources.

关键词： Impedance matching Moment methods Feeds Array signal processing Message-oriented middleware Admittance Antennas and propagation Adaptive arrays Speech processing Electrons

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RADAR BACKSCATTER SIGNATURES OF THIN SEA-ICE IN THE CENTRAL ARCTIC

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INTERNATIONAL JOURNAL OF remote sensing 1994年第5期15卷 1149-1154页

作者： BEAVEN, SG GOGINENI, SP SHANABLEH, M [a]Radar Systems and Remote Sensing Laboratory Department of Electrical Engineering and Computer Science University of Kansas 2291 Irving Hill Road Lawrence Kansas 66045-2969 USA

Monitoring the early stages of sea ice growth is vital because the changing sea ice cover controls the heat exchange between the ocean and air. New ice growth is also responsible for adding brine into the upper portion of the water column. Thin sea ice also significantly affects the albedo of the surface as it changes from a sea surface to an ice surface. To investigate the ability of radars to map thin ice we performed radar backscatter measurements early in the fall freeze-up as part of the International Arctic Ocean Expedition '91 (IAOE'91). We collected data over the thin ice types of light nilas, dark nilas, and pancake/slush ice using a ship-based, C-band FM radar with all four linear polarizations. Our results indicate that radars must be able to measure sigma0 as low as - 30 dB for W polarization and - 34 dB for HH polarization. The noise-equivalent sigma0 for the ERS-1 Synthetic-Aperture Radar is - 24 dB and for RADARSAT is - 23 dB. This implies that these sensors are not capable of monitoring thin sea ice types such as dark nilas and grease ice but may be able to detect slightly thicker ice, such as light nilas and pancake ice, due to their higher backscatter.

关键词： Radar

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Velocity tuned generalized Sobel operators for multiresolution computation of optical flow

Velocity tuned generalized Sobel operators for multiresoluti...

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The 1994 1st IEEE International Conference on image processing

作者： Gökstorp, M. Danielsson, P.-E. Image Processing Laboratory Computer Engineering Division Department of Electrical Engineering Linköping University LinköpingS-581 83 Sweden

Optical flow computation may be divided into four processing steps where the first is extraction of image features suitable for flow estimation. Using a generalization of the basic flow constraint it is possible to estimate flow vectors from a set of feature images obtained from the input image sequence. Generalized Sobel operators provide a suitable set of feature extraction operators. The set of five filters up to second order provides good approximations of ideal edge and line detectors. A review of spatial and frequency constraints on optical flow suggests a multiresolution approach to optical flow where the initial feature extractors consists of velocity tuned operators. We show that two-dimensional generalized Sobel operators may be extended to spatio-temporal velocity tuned filters for optical flow estimation. Experimental results compare well to existing methods. © 1994 IEEE.

关键词： Optical flows

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Parallel D-eigenvalues and parallel D-eigenvectors for linear time-varying systems

Parallel D-eigenvalues and parallel D-eigenvectors for linea...

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Southeastern Symposium on System Theory

作者： J.J. Zhu Electrical and Computer Engineering Department Remote Sensing and Image Processing Laboratory Louisiana State University Baton Rouge LA USA

Singular behavior of PD-eigenvalues of an nth-order scalar polynomial differential operator (SPDO) /spl Dscrsub /spl alpha=/spl deltasup n/+/spl Sigmasub k=1sup nspl alphasub k/(t)/spl deltasup k/spl minus/1/, where /spl delta/=d/dt, is investigated. Main results of this paper include: (i) definition and properties of PD-eigenvectors associated with PD-eigenvalues, (ii) definitions and properties of generalized PD-eigenvectors and generalized PD-eigenvalues for singular PD-eigenvalues; (iii) application of (i) and (ii) in stability analysis of linear time-varying (LTV) systems /spl Dscrsub /spl alpha/spl lcub/y/spl rcub/=0, and (iv) application (i) and (ii) in the realization of PD-characteristic equation. The new results will have a significant impact on applications of the unified eigenvalue theory to the analysis and control of LTV control systems, and its further development.< >

关键词： Time varying systems Eigenvalues and eigenfunctions Control systems Polynomials Stability analysis Control system analysis Riccati equations remote sensing image processing Laboratories

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Meromorphic D-similarity transformation for linear time-varying systems

Meromorphic D-similarity transformation for linear time-vary...

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Southeastern Symposium on System Theory

作者： J.J. Zhu Electrical and Computer Engineering Department Remote Sensing and Image Processing Laboratory Louisiana State University Baton Rouge LA USA

This study constitutes an effort in identifying a class of unbounded coordinate transformations for vector linear time-varying systems of the form x/spl dot/=A(t)x. Main results of this paper include: (i) the definition and properties of meromorphic D-similarity transformations, (ii) two theorems on stability preserving meromorphic transformations. The results appear to be somewhat restrictive, but certainly shed some light on this intriguing yet difficult problem.< >

关键词： Time varying systems Polynomials Vectors Stability analysis remote sensing image processing Laboratories Asymptotic stability

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