高分辨率星载斜视SAR的姿态导引

Attitude Steering for High Resolution Spaceborne Squint SAR

高分辨星载斜视合成孔径雷达回波信号中,多普勒中心频率随距离向的变化通常是十分显著的。这种变化导致系统需要更高的脉冲重复频率来实现方位向无混叠采样。然而,过高的脉冲重复频率将引起严重的距离模糊、极大的数据率,并将限制成像区域大小。本文推导了一种新的全零多普勒导引方法,并在此基础上提出了一种最小化多普勒中心频率随距离变化的姿态导引方法,从而能够最大限度地降低系统脉冲重复频率。根据星地空间几何关系和姿态导引原理,文中推导了实现全零多普勒导引的偏航角和俯仰角的解析表达式,并进一步给出了最小化多普勒中心频率随距离变化的姿态导引规律。最后通过计算机仿真,验证了该方法的有效性。

In terms of high resolution spaceborne synthetic aperture radar（SAR）,the variation of Doppler centroid frequency with range is generally dramatic.Because of this variation,higher pulse repetition frequency（PRF） is required for the sake of non-overlapped azimuth sampling.However,high PRF means severe range ambiguity,huge data rate and constraint on imaging swath.In order to decrease the requisite PRF,a novel method of attitude steering for minimizing the variation of Doppler centroid frequency with range is presented.This method is on the basis of the innovative total zero Doppler steering.According to the imaging geometry and the principle of steering,the analytic expressions of yaw steering angle and pitch steering angle for total zero Doppler steering are concisely derived,and the rule of attitude steering for minimizing the variation of Doppler centroid frequency with range is proposed.Simulations demonstrate the validity of the method in this paper.