任意椭圆轨道下星载SAR多普勒参数的精确计算

国内外已有文献在推导星载SAR多普勒参数计算公式的过程中,均未考虑椭圆轨道下卫星航迹角不为零的影响,这使得已有公式只能近似地使用在近圆轨道上。如果用于大偏心率轨道,误差较大,将严重降低多普勒参数估计过程的收敛速度。为此,本文将航迹角的影响因素考虑在内,推导出可在任意偏心率轨道下使用的计算公式。针对小偏心率和大偏心率轨道,分别设计了一组仿真试验并进行了对比,结果表明:在大偏心率轨道下,航迹角对多普勒参数确有重要影响。

Precise computation of Doppler parameters for spaceborne SAR in arbitrary elliptic orbits

The fact,that the flight-path angle of a satellite is not equal to zero in elliptic orbits,is neglected in the deduction processes of the existing formulae that are used to compute the Doppler parameters for spaceborne SAR.The consequence is that the existing formulae can only be approximately used in nearly circular orbits.If the existing formulae are applied to a satellite with large eccentricity,the error may be so large as to cause the convergence speeds of Doppler parameters estimation algorithms to decrease significantly.This paper derives several precise analytical formulae that can be used for satellites with any eccentricity.During the deduction process,the effect of flight-path angle is considered as a key issue.Two simulation experiments are performed,one for a small eccentricity orbit while the other for a large eccentricity orbit.Results show that when the eccentricity of the orbit is relatively large,the flight-path angle of satellite indeed has strong effects on the Doppler parameters of spaceborne SAR.