分布式星载SAR系统时间同步和波束同步误差分析

三大同步是分布式星载SAR系统需要解决的关键问题之一。该文系统分析了时间同步和波束同步误差对分布式星载SAR系统的影响，时间同步部分首先推导了时间同步误差对成像的影响，其次基于时间同步误差模型和脉冲对传相位同步模型，分析时间同步和相位同步导致的相位误差之间的关系，波束同步部分基于星载双基SAR系统的不同姿态导引方式，分析波束指向误差和卫星姿态误差对合成天线方向图的影响，以及对多普勒去相干的影响，最后分析波束同步误差对距离向重叠幅宽的影响。仿真结果验证了本文理论分析的正确性，分析结果可以为分布式星载SAR的系统设计提供重要指导。 

Analysis of Time and Beam Synchronization Errors for Distributed Spaceborne SAR System

Synchronization is a key problem in distributed Synthetic Aperture Radar (SAR) systems. In this paper, we perform a complex mathematical deduction and then analyze the influences of time synchronization on the SAR imaging and interferometric process. We discuss the relationship between time and phase synchronization, considering that different oscillators in separated transmitters and receivers lead to both time and phase synchronization errors. With respect to beam synchronization, we present the effects of the accuracies of beam pointing and satellite attitude on the antenna gain, based on the attitude-steering strategy, which involves azimuth weighting of the Doppler spectra for independent zero-Doppler beam steering. We also analyze the influences of beam synchronization on Doppler decorrelation, Signal-to-Noise Ratio (SNR), and overlapping swath error. We conduct simulations to validate the analysis results. Our findings provide guidance for system design.