Effects of residual motion compensation errors on the performance of airborne along-track interferometric SAR

在机载合成孔径雷达(synthetic aperture radar,SAR)运动补偿中一般存在两个近似:波束中心近似和参考高程近似,这两种近似会在机载单天线SAR系统和机载干涉SAR系统成像过程中引入运动补偿残余误差。本文针对机载顺轨干涉SAR(airborne along-track interferometric SAR,ATI-SAR)系统,分析了上述两种近似导致的运动补偿残余误差对干涉性能的影响。首先针对机载双天线ATI-SAR系统,在不存在参考高程误差和存在参考高程误差两种情况下分别推导了其运动补偿残余误差,然后利用机载仿真参数证明了推导公式的正确性,并展示了运补残余误差对ATI-SAR干涉相位的影响程度。结果表明,当不存在参考高程误差时,由于运补残余误差导致的干涉相位误差可以忽略;而当存在参考高程误差且参考高程误差大于某个门限值时,对于相应的测速精度要求,由于波束中心近似导致的干涉相位误差不可忽略。本文的研究为机载ATI-SAR误差源分析和信号处理提供了理论基础。

Two approximations, center-beam approximation and reference digital elevation model （DEM） approximation, are used in synthetic aperture radar （SAR） motion compensation procedures. They usually introduce residual motion compensation errors for airborne single-antenna SAR imaging and SAR interferometry. In this paper, we investigate the effects of residual uncompensated motion errors, which are caused by the above two approximations, on the performance of airborne along-track interferometric SAR （ATI-SAR）. The residual uncompensated errors caused by center-beam approximation in the absence and in the presence of elevation errors are derived, respectively. Airborne simulation parameters are used to verify the correctness of the analysis and to show the impacts of residual uncompensated errors on the interferometric phase errors for ATI-SAR. It is shown that the interferometric phase errors caused by the center-beam approximation with an accurate DEM could be neglected, while the interferometric phase errors caused by the center-beam approximation with an inaccurate DEM cannot be neglected when the elevation errors exceed a threshold. This research provides theoretical bases for the error source analysis and signal processing of airborne ATI-SAR.