弹载SAR下降段成像算法研究

Research on the imaging algorithm for missile-borne SAR with downward movement

弹载SAR下降段成像中,弹体较大的下降速度和加速度将导致SAR回波信号的多普勒调频率沿方位向变化,影响方位聚焦.针对该问题,提出了一种利用方位非线性变标(NLCS)的弹载SAR下降段成像算法.该算法在距离徙动校正和距离压缩处理之后,通过引入方位非线性变标操作,补偿变化的多普勒调频率,并校正图像方位畸变,从而改善了方位聚焦深度和聚焦质量.数据仿真结果验证了算法的有效性.

During the downward movement for Missile-Borne SAR imaging, variation of Doppler FM rates for echo signal severely affects the focusing effect, which is introduced by high vertical velocity and acceleration. For this reason, by using azimuth nonlinear chirp scaling （ NLCS）, an imaging algorithm for Missile-Borne SAR is proposed in this paper. After range cell migration correction and range compression, variation of Doppler FM rates for the echo signal can be compensated and image distortion can be corrected by the operation of azimuth nonlinear chirp scaling, thus improving the focus depth and focusing effect. Simulation results are provided to validate the effectiveness of the proposed algorithm.