A novel FFBP-based autofocus for SAR imaging

Fast factorized back projection (FFBP) is capable to be applied almost in all kinds of SAR imaging. However, due to the residual motion errors (RME) preserved in the SAR images, autofocusing must be carried out under the framework of FFBP to achieve high-quality SAR images. In this paper, a new autofocus method is proposed based on FFBP algorithm. It explores the point-like targets distributed in the defocused images to get the first derivative of the RME, and then by an integration operation, the RME is obtained. Simulated and real SAR data are used to demonstrate its feasibility and effectiveness.