Airborne radars are potentially vulnerable to ground bounce jamming, where the jammer illuminates terrain in the radar's search beam. This poses a difficult ECCM problem, since the scattered jamming arrives from a large region with a spread in both delays and Doppler shifts. The radar must suppress both the ground bounce jamming and ground clutter return. The proposed study addresses adaptive signal processing techniques as a solution to this problem in surveillance radars. The proposal contains simulation results showing that multiple auxiliary beams, each containing scattered jamming from a different area on the ground, can be used successfully as auxiliary inputs to a ground bounce jamming canceler. Simulation and flight tests have shown that space-time adaptive processing (STAP) is an effective method of suppressing clutter and detecting moving targets in airborne radars. During the Phase I study, different signal processing architectures for simultaneously rejecting both types of interference, using multiple beams as ground bounce jamming auxiliary inputs and STAP for clutter cancellation, will be simulated and compared in performance and complexity. Anticipated Benefits/Potential Applications - The techniques developed on this program will lead to improved capability for detecting moving targets from airborne radars. The most important current applications are improved ECCM and ability to detect low echo area targets in DoD radars. The interference suppression capability will also be important in future commercial radars and communication systems.