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Aerospace and Electronic Systems Magazine, IEEE

Issue 5 • Date May 1991

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Displaying Results 1 - 6 of 6
  • Radar target classification and interpretation by means of structural descriptions of backscatter signals

    Publication Year: 1991 , Page(s): 3 - 7
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (522 KB)  

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

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  • High-resolution multiple target angle tracking

    Publication Year: 1991 , Page(s): 8 - 12
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (429 KB)  

    An approach to high-resolution multiple-target-angle tracking that uses the output of an array of sensors is presented. The results of direction-of-arrival estimation by eigenstructure analysis are extended to derive a recursive procedure for tracking moving sources. This procedure involves recursive eigenvalue decomposition and a zero-tracking algorithm, using the coefficient derived from the minimum-norm criterion. The algorithm has superresolution capability in that a pair of closely spaced target angles can be resolved and tracked even though the angular separation between them is less than the reciprocal of the aperture size. Simulation results verify that the algorithm works well in tracking multiple-target sources.<> View full abstract»

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  • A space-fed phased array for surveillance from space

    Publication Year: 1991 , Page(s): 13 - 17
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (513 KB)  

    A space-fed radar antenna called a venetian blind is proposed for all-weather wide-area surveillance from space. Radar requirements for tasked and untasked operation are discussed, and the process of selecting the venetian blind concept, which can support both, is described. In its untasked form (essentially a space-fed passive lens), it achieves off-axis squint angles of many beamwidths with negligible performance degradation. It is inherently insensitive to mechanical distortion and is a first step in the evolution to the more complex tasked system antenna. The antenna lens consists of easily manufactured slats with microstrip dipole radiating elements and matching networks on a dielectric substrate. Phase control is achieved with low-loss delay lines in the passive lens or active transmit/receive modules if electronic scan is desired.<> View full abstract»

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  • A flexible processor for a digital adaptive array radar

    Publication Year: 1991 , Page(s): 18 - 22
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (489 KB)  

    A digital beamforming processor for an adaptive array radar is described. The functionality and the architecture of the processor are strongly driven by a goal of achieving adaptive null depths in the 60-dB to 70-dB range, which necessitates substantial preprocessing of each channel. In particular, conversion to baseband quadrature channels is accomplished digitally using a single A/D converter per channel, and FIR (finite impulse response) equalizing filters are employed in each channel to match channel transfer functions. The processor is highly modular, and this not only distributes the total processing load, but also the I/O (input/output) bandwidth requirement. This is accomplished by distributing the adaptive beamforming algorithm systolically across a linear array of processing nodes. The processor is expandable to a different number of channels and sufficiently flexible to be applied to other problems of an array signal processing nature. Experimental data presented demonstrate that the processor is capable of supporting channel-to-channel cancellation of interfering signals to the level of -65 dB.<> View full abstract»

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  • Missing radar pulse clutter processing

    Publication Year: 1991 , Page(s): 23 - 27
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (403 KB)  

    The degradation of conventional clutter processing filters due to missing pulses resulting from RF interference blanking, ambiguous range returns when no filter pulses are used, or eclipsing is described. The effects of a missing pulse on uncompensated and optimum clutter filters are investigated. The maximum improvement factor method and other methods are compared to the optimum filtering. New methods and results using a minimax log energy search method are described and are shown to provide performance and/or implementation complexity advantages.<> View full abstract»

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  • Pulse Doppler signature of a rotary-wing aircraft

    Publication Year: 1991 , Page(s): 28 - 30
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (290 KB)  

    Field measurements of a modified Sikorsky S-55 helicopter target were carried out to investigate rotary-wing aircraft Doppler radar signature phenomenology. The results of the data analysis with regard to classification and identification of the aircraft based on its signature are presented. It was found that using the Doppler radar return and appropriate feature extraction techniques, the helicopter's design features can be estimated. Target backscatter from the main rotor blades, tail rotor blades, or hub can be used for target detection, acquisition, and classification as a rotary-wing aircraft. The extraction of configuration and blade count features can further define the helicopter for identification.<> View full abstract»

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The IEEE Aerospace and Electronic Systems Magazine publishes articles and tutorials concerned with the various aspects of systems for space, air, ocean, or ground environments.

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