二阶运动补偿对低频超宽带SAR视线误差补偿的影响

Second-order Motion Compensation Effects on Light of Sight Error Compensation in Low-frequency Ultra Wide-band SAR

视线误差补偿是低频超宽带合成孔径雷达(UWB SAR)成像处理的关键,该文主要研究基于测量数据的距离空变视线误差补偿,即二阶补偿。标准的二阶补偿在推导的过程中,对回波进行了一定的近似,认为距离空变视线误差对回波距离迁徙校正(RCMC)没有影响,而这个近似条件,在低频超宽带SAR中是不满足的。针对这个问题,该文对二阶补偿在低频超宽带SAR中的应用进行了分析,研究了3种二阶补偿方法,即:二阶补偿位于RCMC之后完成;二阶补偿位于RCMC之前完成;沿距离向划分子带进行二阶补偿。文中对3种二阶补偿方法进行了对比分析,并对每种补偿方法中存在的误差进行了分析。最后采用仿真以及实测低频超宽带SAR数据验证了文中分析的正确性。

The MOtion COmpensation（MOCO） of Light Of Sight（LOS） error is very important in low-frequency Ultra Wide-Band Synthetic Aperture Radar（UWB SAR）.In this paper,the second-order MOCO is studied which compensate the range-variant component of LOS error.In second-order MOCO,the assumption that there is no effect of range-variant LOS error on the Range Cell Migration Correction（RCMC） is supposed,which is not satisfied in UWB SAR.This paper analyzes the application of the second-order MOCO in low-frequency UWB SAR.Three methods which can be applied to compensate the range-variant LOS error are presented.First method implements the second-order MOCO after RCMC,second method implements it before RCMC,and the last method implements it in sub-band which is split along range direction.The three methods are compared and analyzed in this paper.Finally,the effectiveness of theoretical analysis is validated with simulation and real low-frequency UWB SAR data.