An On-Board Imaging Processing Algorithm for Stripmap Mode of Azimuth Multichannel Spaceborne SAR

Abstract

In the traditional processing methods of azimuth multi-channel spaceborne synthetic aperture radar (SAR), the azimuth spectrum reconstruction and subsequent azimuth focusing are always via full-aperture processing. However, if the multi-channel full-aperture echo data are stored on the satellite, and then the full-aperture algorithms are used for the on-board imaging processing, the huge amount of echo data will require more on-board storage resources and computing resources, and the imaging processing time will become longer. To solve above problems, a novel on-board imaging processing algorithm via the idea that the data acquisition and the on-board imaging processing of the sub-aperture data are carried out simultaneously is proposed in this paper. In the algorithm, the azimuth spectrum ambiguity is eliminated by the sub-aperture azimuth spectrum reconstruction. Then, the range cell migration correction (RCMC) and the range compression for the unambiguous sub-aperture signals are accomplished by the chirp scaling algorithm (CSA). After that, the low-resolution subaperture images are got via the sub-aperture focusing. By coherently combining all sub-aperture images, the final result with high-resolution of all echo data can be obtained. At last, the simulation for the point targets is given to verify the effectiveness of the proposed algorithm.