A Novel GMTI Method Based on Masking Technique

A novel approach of Ground Moving Target Indication (GMTI) based on subapertures and masking is developed in this paper. At first, Range Compressed and Azimuth Unfocused (RCAU) complex SAR image is split into two subapertures symmetrically in azimuth. Due to different behaviors of moving target and stationary target between the two subapertutes, the stationary target can be canceled and the moving target can be reserved by subtraction between the subapertures. The trajectory of moving target can be recovered and a image mask can be formed from this difference image. The phase history of the moving target can be restored on this mask by multiplying with the RCAU complex image. Then, the moving target is focused with a wider Doppler band matched filter and refined with Phase Gradient Autofocus (PGA) to aggregate energy and enhance detection probability. Finally, the moving target is detected with a 2-D Constant False Alarm Rate (CFAR). Combined with Along-Track Interferometry (ATI) the approach can extend velocity range of moving target extensively.