高低轨异构双基地SAR改进CS成像算法

针对地球同步轨道卫星发射-低轨道卫星被动接收的异构双基合成孔径雷达系统中，由于收发时延长和接收机速度快导致的“走-停”假设不成立，复杂成像几何下回波信号在距离向和方位向具有严重空变性的问题，提出一种基于二维时域扰动的改进线性调频变标成像算法．首先基于双基观测几何推导出非“走-停”假设下的信号模型；然后通过时域扰动的方法校正回波二维空变性；最后对残余相位进行补偿．仿真实验表明，该算法可实现高低轨双基合成孔径雷达高分辨率宽幅场景的良好聚焦，且具有很好的保相性能．

Improved CS imaging algorithm for the GEO-LEO BiSAR system

In the spaceborne bistatic synthetic aperture radar (BiSAR) system with a geosynchronous (GEO) illuminator and a low-earth-orbit (LEO) receiver, due to the long signal propagation time and high receiver velocity, the slant range error caused by “Stop-and-Go” assumption cannot be neglected. In addition, the spatial-variant characteristics of the echo signal caused by the complex bistatic configuration need to be considered. In this paper, an improved Chirp Scaling (CS) algorithm based on the time-domain perturbation is proposed. First, the signal model is derived based on the geometry. Then, the perturbation functions for correcting the spatial-variant characteristics are presented. Last, the phase compensation functions are generated to enhance the capability of the algorithm. Simulated data results show the validity of the presented method. The algorithm proposed in this paper is able to implement wide-swath and high-resolution imaging and produce the phase-preserved SAR image.