基于Chirp_z变换与方位变标地球同步轨道SAR成像算法

针对地球同步轨道合成孔径雷达(GEO SAR)成像距离向处理复杂，方位向空变性强问题，该文提出一种基于Chirp_z变换与方位变标的成像算法。首先在回波模型中考虑停-走-停假设带来的相位误差，然后给出目标点的斜距表达式，并利用泰勒级数对斜距进行了高阶展开，通过级数反演法得到信号频谱表达式，利用高效的Chirp_z变换校正距离走动，简化距离向处理，利用改进的变标因子校正方位向信号一次，二次，三次展开项系数线性时变性，并在方位频域内补偿变标操作引入的相位误差。仿真结果表明该算法能够实现地球同步轨道SAR聚集成像。

Imaging Algorithm for Geosynchronous Orbit SAR Based on Chirp_z Transform and Azimuth Scaling

Aiming at the problem of complex range processing and strong azimuth variant in GEosynchronous Orbit SAR (GEO SAR) imaging processing, an imaging algorithm based on Chirp_z transform and the azimuth scaling is proposed. Firstly, the stop-go-stop phase error is considered in the echo model, and then the slant distance expression which is expanded using the Taylor series is given. After that, a series of inversion method is used to get the signal spectrum expression. In order to simplifying the imaging processing at range direction, the Chirp_z transform is used to correct the range walk. And then, an improved scale factor is used to correct the linear time-varying coefficient of signal expand included the first order, the second order and the three order. The phase error introduced by scaling operation is compensated in frequency domain. Finally, the simulation results show that the algorithm can realize geosynchronous orbit SAR imaging.