Preliminary Results of Hot
|Larry E. Brennan
Adaptive Sensors, Inc.
P.O. Box 590
Orange Beach, AL 36561
Abstract Jamming scattered from terrain (hot clutter) into the main beam may limit the performance of radars, particularly high performance systems using digital adaptive processing to detect low echo area targets in clutter and sidelobe jamming. The angular nulling and Doppler filtering techniques effective against radar clutter and sidelobe jamming are not capable of suppressing hot clutter, which is spread in delay, angle, and bistatic velocity. Methods of canceling hot clutter using adaptive transversal filters in auxiliary channels, either beams pointed at jammers or other beams containing hot clutter, have been proposed and validated by simulation.
Terrain scattered jamming was recorded at White Sands Missile Range (WSMR) using the MIT Lincoln Laboratory RSTER radar. This data was used to test the performance of hot clutter cancellation algorithms. In the early recorded data, the jammer was located on a mountaintop so the scattering process was not changing. Results obtained with this data demonstrated the presence of hot clutter and feasibility of canceling both radar clutter and scattered jamming. Later data was recorded with an airborne jammer illuminating the terrain. Mitigation is more difficult in this case due to the rapidly changing scattering process (bistatic Doppler spread). The distribution of hot clutter in delay and bistatic Doppler was observed by cross-correlating the hot clutter input with the output of a beam pointed at the jammer. Some preliminary results of hot clutter cancellation tests using the airborne jammer data are presented.
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