地形数据误差对宽波束SAR运动补偿的影响

Effect of outer DEM precision on ride-beam SAR motion compensation

随着合成孔径雷达(SAR)技术的发展,各种应用如重轨干涉、差分干涉等,对雷达图像的要求也在变高。在机载SAR系统中,随着波束角变宽,传统的基于平地假设的运动补偿算法,已经无法再满足应用需求,需要使用外部DEM才能得到好的补偿效果。本文主要研究外部DEM精度对宽波束SAR运动补偿的影响,分析了不同高程误差条件下,由运动误差带来的视线向斜距差异,得到各种运动误差补偿后对成像质量的影响,然后针对对图像的相干性受残余运动误差的影响进行了理论推导,并通过仿真实验进行了验证,结果证明了理论分析的正确性。

Along with the development of synethic aperture radar （SAR） technology,many applications of （SAR）, such as repeat-pass interferometry SAR（InSAR）, and difference InSAR, require higher quality images. The traditional motion compensation （MoCo） method for airborn SAR based on flag-earth hypothesis could not meet the requirement as the beam width arises. As a result,outer digital elevation model （DEM） data is introduced for more accurate compensation. This paper mainly focuses on the effect of outer DEM precision on wide-beam SAR MoCo. Different motions and outer DEM errors are analyzed to gain the effect on range errors along light of sight（LOS）, and on image qualities after MoCo. Image coherence affected by residual motion error is also derived. Emulations support the result.