一种改进的星载分布式SAR相位保持成像算法

摘要

针对Chirp Scaling算法在推导中对相位采用近似处理而导致相位保持精度不能满足分布式星载InSAR系统对高程测量精度要求的问题,在对线性调频信号脉压处理中相位变化规律进行分析的基础上,结合星载分布式SAR数据处理对信号相关性的要求,推导了适用于星载分布式SAR数据处理的相位补偿公式,进而提出一种能够实现高精度相位保持的改进Chirp Scaling成像算法.算法精确补偿了包括复常数相位项、移零频所引入的线性相位项、距离向残留三次相位项及距离压缩后非均匀采样所引入的相位误差,并且能够实现分布式InSAR复图像对的粗配准.最后,给出了一种理论相位的计算方法,并通过计算机仿真验证了算法的有效性.%The approximate treatments in chirp scalinS ( CS) algorithm lead to phase errors, and unable to satisfy the requirement for height measurement accuracy of spaceborne distributed interferometric synthetic aperture radar ( InSAR) .In this article, on the basis of analysis for characteristics of residual phase error during pulse compression processing, a phase compensation function is derived in combination with the coherence requirements for spaceborne distributed InSAR data processing. And then an improved phase preservation chirp scaling algorithm is proposed to accurately compensate the phase errors, i. e. constant phase term,linear phase ermr term caused by shifting zero-frequency. residual cubic phase error term along range-direction and nonuniform sampling phase error term after range-compression. Furthermore, the improved algorithm has the capability to primarily implement registration procedure for distributed InSAR. Moreover, a method for calculating the theoretical phase function is presented. Finally , computer simulation results demonstrate the effectiveness of the proposed algorithm.