基于Hermite的SAR卫星轨道插值干涉测量应用研究

Research and Application of in SAR Satellite Orbit Interferometry Based on the Hermite Interpolation

合成孔径雷达(SAR,synthetic aperture radar)卫星轨道参数是干涉测量技术中影像配准、基线估算、平地相位去除等环节的重要参数,但部分SAR卫星轨道参数采样间隔较大,导致干涉测量过程中产生残余相位,发生较大的系统误差;利用编程工具,对卫星原始轨道状态矢量进行了埃尔米特插值法拟合,等距插值计算后,发现可以缩小轨道参数采样间隔,提高干涉测量精度;以覆盖巴姆地区的Envisat卫星为例,分别获取了基于粗轨、埃尔米特插值轨道参数和代尔夫特精密轨道参数得到的干涉测量图,定性判断出埃尔米特插值法可有效提高SAR卫星轨道精度;再以覆盖陕西地区的AOLS卫星为例,插值轨道矢量采样间隔分别为10秒、5秒、2秒,发现间隔为5秒时相干性最优;结果表明:采用埃尔米特插值法可有效增加SAR卫星轨道状态矢量数量,消除系统误差,提高干涉测量精度。

Satellite orbit parameters of synthetic aperture radar(SAR)are important parameters for image registration,baseline estimation and phase removal from flat ground in interferometry technology.However,the large sampling interval of some SAR satellite orbit parameters leads to residual phase and large systematic errors in the interferometry technology.In this paper,the programming tool is used to fit the original orbit state vector of the satellite by the Hermite interpolation method,and the isometric interpolation calculation is used to reduce the sampling interval and improve the accuracy of interferometric measurement.Taking the Envisat satellites covering the Bam area as an example,the interferometric maps based on rough orbit,the Hermite interpolation orbit parameters and the Delft precision orbit parameters are obtained separately,and it was qualitatively concluded that the Hermite interpolation method could effectively improve the orbit accuracy of the SAR satellites.Taking the AOLS satellite covering Shanxi province as an example,the sampling interval of interpolation orbital vector is 10 s,5 s and 2 s respectively,and it is found that the coherence is optimal when the sampling interval is 5 s.The results show that the Hermite interpolation method can effectively increase the number of the SAR satellite orbit state vectors,eliminate the systematic errors and improve the accuracy of interferometry.