ADAPTIVE SIGNAL PROCESSING ALGORITHM DEVELOPMENT FOR AIRBORNE EARLY EARNING RADAR

The detection of low velocity targets by a high PRF surveillance radar such as the E-3 AWASCS is exacerbated by the two different clutter return phenomena: the J-Hook return and the Horseshoe return. The J-Hook return is observed primarily when the antenna points downward. In these geometries the clutter screen below the antenna may not adequately suppress the elevation sidelobe return, which allows the J-Hook return to become strong.The Horseshoe return, which is viturally always present, is believed to be caused by reflections from the AWACS radome. The Horseshoe return tends to track near the aircraft's nadir point.The proposed research will provide greater insight into the causes of these two clutter returns. Also, the algorithms that will be investigated to mitigate these effects are described. The algorithms, which vary considerably in complexity operate at various levels including: 1) censoring the clutter retruns in the CFAR map, 2) multiple slant adaptive processing and 3) both single and multiple channel adaptive antenna processing.