一种方位时变GEO SAR成像处理新算法

针对地球同步轨道合成孔径雷达(GEO SAR)回波模型的距离空变和方位时变问题，提出一种基于改进距离-多普勒(RD)和方位向调频尺度变换(CS)的成像算法。首先引入四阶泰勒展开模型解决成像中存在的弯曲轨迹问题，然后对传统RD算法进行改进，补偿距离空变，最后对方位时变进行建模，通过方位向CS补偿方位时变，使GEO SAR能够进行更大场景的成像。结合天基雷达先进仿真系统(SBRAS)进行仿真，验证了该算法的有效性。

A New Algorithm for Azimuth Variant GEO SAR Imaging

In order to compensate the range and azimuth shift variations of the echo model in geosynchronous synthetic aperture radar (GEO SAR) imaging, an algorithm based on improved range doppler and azimuth chirp scaling (RD ACS) is proposed in the paper. First, the slant range model with 4 order Taylor expansion is introduced to solve the curved trajectory problem in GEO SAR imaging. Then, the conventional range doppler algorithm (RDA) is improved to compensate the range shift variation. And, an additional azimuth chirp scaling (ACS) is designed to compensate the azimuth shift variation according to a new azimuth variant model. The 2 dimensional (range and azimuth) focusing scope in GEO SAR imaging is enlarged obviously. The validity of the new algorithm is validated by the simulations with the space borne radar advance simulator (SBRAS).