An ISAR Approach for Refocusing the Maritime Moving Targets With the GF-3 SAR Satellite

Moving ship targets are always defocused in synthetic aperture radar (SAR) images under the influence of self-motion and sea waves. Inverse SAR (ISAR) technique is commonly used to focus non-cooperative targets by motion compensation. A novel refocusing method, improved rank one phase estimation (IROPE), is proposed in this paper. The ISAR processing is based on the proposed method, an iterative two-step convergence approach to obtain the phase error. The performance of the proposed method is tested by comparing it to other focusing algorithms using real spotlight complex image data of Gaofen-3 (GF-3) spaceborne SAR system. Results verify the effectiveness of the proposed method.