星载SAR椭圆轨道全零多普勒导引方法研究

摘要

Doppler centroid frequency influences the azimuth ambiguities and the location accuracy directly.Total zero Doppler steering method isused to reduce the Doppler centroid frequency to 0Hz by adjusting the yaw and pitch,but residual Doppler centroid frequency still exists.In the paper,the Doppler centroid frequency expression based on elliptical orbit is derived analytically.The Doppler centroid frequency is divided into two parts： one part is related to only pitch,and the other part is related to both yaw and pitch.Assume the two parts are both equal to zero.The pitch angle is calculated firstly,and then the yaw angle is concluded.The residual Doppler centroid frequency is almost 0Hz.The TerraSAR-X satellite parameters are used in the simulation.The simulation results indicate that the residual Doppler centroid frequency is about 0.03Hz,which is much smaller than that of the instantaneous circular orbit total zero Doppler steering,so the new method completes total zero Doppler steering effectively.%多普勒中心频率在星载合成孔径雷达（SAR）成像中,直接影响方位向的模糊度及图像的定位精度。全零多普勒导引方法通过调整偏航角和俯仰角,使多普勒中心频率为零,但现有方法都导致残余多普勒中心频率较大。文章利用椭圆轨道下多普勒中心频率的表达式,将多普勒中心频率分为仅与俯仰角相关部分,以及与俯仰角和偏航角都相关的部分,令两部分分别等于零,首先求得俯仰角,再利用俯仰角得到偏航角,从而有效地减小了残余多普勒中心频率。利用德国＂陆地合成孔径雷达-X＂（TerraSAR-X）卫星参数进行仿真,结果表明：使用文章提出的方法,