星载寄生式InSAR系统相关性及相对测高精度分析

结合星载寄生式干涉合成孔径雷达(InSAR)的工作原理及高稳定频率源的工作特性,给出了时间和频率同步误差模型。基于该误差模型,分析了时间和频率同步误差对干涉相位的影响,首次推导了同步误差导致的信号去相关。基于星载寄生式InSAR系统的空间几何关系和图像信号模型,详细分析了热噪声、模糊、量化噪声、基线、方位向、配准误差及体散射等去相关效应,给出了考虑上述全部去相关因素时系统的相对测高精度,并仿真分析了以Envisat为主星的寄生式InSAR系统在ASAR雷达7个不同波位下的相对测高性能。理论分析和仿真结果表明,在合理选择轨道和雷达参数的前提下,系统可以达到很好的测高精度。

Analysis of Correlation and Relative Height Accuracy for Spaceborne Parasitic InSAR System

The time and frequency synchronization error models are given according to the theory of spaceborne parasitic interferometric synthetic aperture radar(InSAR) and the work characteristic of ultra stable oscillator(USO).The effect of time and frequency synchronization error on interferometric phase is analyzed based on the error models.The decorrelation caused by the time and frequency synchronization errors is presented for the first time.Based on the formation configuration and image signal model of the spaceborne parasitic InSAR system,the thermal noise decorrelation,ambiguity noise decorrelation,block adaptive quantization(BAQ) noise decorrelation,baseline decorrelation,Doppler decorrelation,mis-coregistration decorrelation and volume scatter decorrelation are analyzed.The relative height accuracy of the system is deduced when all the signal decorrelations are taken into account.The relative height accuracy of the seven sub-swaths of ASAR system on Envisat is simulated.The theory analysis and simulation results indicate the spaceborne parasitic InSAR system can achieve perfect performance if the orbit and radar parameters are correct designed.