Constrained partially adaptive space-time processing for clutter suppression

A major problem in airborne radar or moving platform active sonar systems is the detection of low-Doppler target returns embedded in spatially distributed and Doppler-spread clutter returns received in a radar antenna or sonar array. This paper presents two novel partially adaptive space-time processing techniques for improving low-Doppler target detection which are based on employing an adaptive preprocessing structure composed of transversal FIR filters in each subarray of a partitioned planar array. Both methods use substantially reduced adaptive degrees of freedom compared to the “optimal”, fully adaptive space-time processing method with attendant significant computation advantages and improved performance in a nonstationary environment. Computer simulation results are presented that demonstrate the improved performance of the proposed techniques over conventional beamforming and filtering methods