A Method for Calculating the Optimal Velocity Search Step Size for Airborne Three-Channel SAR Adaptive Clutter Suppression

For multichannel synthetic aperture radar (SAR) ground moving target indication (GMTI) systems, the clutter suppression method based on post-Doppler space time adaptive processing technology is popular due to its excellent performance. However, to coherently integrate a target's energy of each channel, this kind of method requires a search of target's velocity, which would introduce a large computation load when the search step size is too small. While the existing studies mainly focus on improving its performance in the cases of complex scenes and geometries, the studies on optimizing the search step size are rare. To address this issue, this article proposes a method for calculating the optimal velocity search step size of adaptive clutter suppression for the commonly used airborne three-channel SAR-GMTI systems. First, the signal models in the range Doppler domain are developed. Then, considering that both the signal-to-clutter-noise ratio loss of clutter suppression and the coherent integration gain loss are introduced by the mismatch of target's steer vector, the relationship between the coherent accumulation gain loss and the velocity search error is utilized to develop the analytical expression for the optimal velocity search step size. Experimental results validate the proposed method.