Highly Squinted TOPSAR Imaging Based on Improved CS Algorithm

In order to meet the demand of highly squinted spaceborne or airborne TOPSAR imaging, in this paper, we study TOPSAR working mode in depth and propose a new improved CS algorithm based on time-domain range walking correction and azimuth nonlinear chirp scaling. Firstly, we theoretically analyze the signal model of highly squinted TOPSAR working mode in detail, and then comprehensively considering various important factors affecting the focusing performance of highly squinted TOPSAR algorithms, we design corresponding improvement measures to effectively compensate the two-dimensional space variances of range and azimuth frequency-modulation (FM) rate, the RCM space variance and the cubic term. In addition, the proposed algorithm is designed to resolve the ambiguity caused by azimuth spectrum alias and image time-domain alias. The algorithm proposed by this paper does not need to divide the aperture and avoid interpolation, and has high computation efficiency. Finally, the effectiveness and advantages of the proposed algorithm are verified by simulation experiments.