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THIRD ANNUAL
ASAP '95 WORKSHOP

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Cancellation of
Terrain-Scattered
Interference (TSI)

William C. Jones, Jr.
Westinghouse Electric Corporation
Baltimore, MD 21203

Abstract
This presentation introduces an approach for canceling terrain-scattered interference (TSI), or "hot clutter,'' in a high PRF airborne fire-control radar with a forward looking array antenna. TSI signals are modulated versions of a direct path jamming signal, and this presentation shows how the signal characteristics motivate an algorithm and antenna architecture for canceling them. Specifically, TSI is primarily a mainbeam problem, and each scattered signal component is a time-delayed, Doppler offset, eclipsed version of the jamming waveform. Each of these factors is shown to influence the cancellation techniques.

Results are shown for a beamspace approach, utilizing a monopulse beam cluster and employing multiple time taps, and Doppler offset channels. Simulation results show 12­20 dB of cancellation, to near or below noise level, and restoration of target detectability. Eclipsing effects of a high PRF waveform with 25% duty factor are included. The simulation uses a detailed model of the bistatic clutter environment.

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