MTPT方法估计机载SAR残余运动的两个影响因素

Two Factors Influencing Residual Motion Estimation in Airborne SAR Images with MTPT

由于导航系统测量精度的限制,载机的位置经常存在厘米级的误差,该误差称为残余运动误差。对于机载超高分辨SAR系统或机载重轨干涉SAR,必须估计并补偿该残余运动误差。MTPT方法可以估计单幅SAR图像中的残余运动误差,但是速度和斜距的误差会影响该方法的精度。该文在详细分析速度和斜距误差对MTPT方法进行残余运动估计的影响的基础上,利用仿真和实测SAR数据验证了这一点。同时还指出,MTPT方法虽然可以估计速度和斜距误差,但是它们的精度敏感于相位测量误差;在利用MTPT方法进行估计之前必须先利用其它更为准确的方法消除平台的速度误差和目标的斜距误差。

Due to the poor accuracy of navigation systems, deviations of the order of centimeters between the real and measured trajectories, called residual motion errors, frequently occur ill SAR images. For airborne SAR systems with very high resolution and airborne repeat-pass SAR interferometry, the residual motion errors must be estimated and compensated. Multi-squint Technique with Point Targets （MTPT） is able to estimate the residual motion errors for an individual SAR image, but errors in the platform velocity and the slant range will deteriorate the accuracy of the method. In this paper, we validate this by performing detailed analysis of the velocity and slant range to residual motion error estimation using both simulated arid real SAR data. It is also shown that MTPT is able to estimate the errors in the velocity and slant range, and it is sensitive to the phase error. Therefore, it is advised that the errors in the velocity and slant range should be removed using other precise methods before MTPT is utilized to estimate the residual motion errors.