An Autofocus Algorithm Based on Topography Searching for Airborne SAR

The coupling effect between the motion error and the topography results in quality degradation of the airborne SAR image. An autofocus algorithm based on topography searching is proposed to improve the focusing quality. It adjusts the target height to compute the motion compensation amount, and then selects the one with the best focusing quality as the final result. The algorithm is implemented by a block-by-block scheme to process the coarse-focused image, so the focusing quality of the whole image can be proved. The proposed algorithm is validated by simulation results.