A High Quality Processing Algorithm for Space-borne Spotlight SAR

Abstract:
A high quality Space-borne spotlight SAR processing Algorithm is presented, which mainly consists of the Deramp Range Migration (DRMA) and the estimation of the autofocusing parameters. Based on the Two-step algorithm and range migration algorithm, the DRMA for the high-resolution satellite-borne spotlight SAR is presented, which combines the advantages of SPECAN algorithm and Range Migration algorithm. Firstly, the proposed algorithm perform a bulk azimuth raw data compression and to achieve a pixel spacing no larger than the expected azimuth resolution of the fully focused image. Therefore, the azimuth spectral folding phenomenon is overcome. Secondly, the residual and precise focusing of the SAR data is achieved by applying the Range Migration which should be modified. Besides, the velocity and squint angle are important parameters for the DRMA. The estimation of the two parameters could be circumvented through estimating the Doppler parameters of the target locating in the centre of the scene. In order to avoid the azimuth spectral folding, the full aperture is divided into subapertures. Finally the least square technology is used to determine the Doppler centroid from the Doppler centroids of subapertures. And the Doppler frequency rate is achieved by the mapdrift technology. Presented results confirm the validity of the proposed algorithm.