MIMO下视阵列SAR倾角误差补偿算法

Inclination Angle Error Compensation Algorithm of MIMO Downward-looking Array SAR

结合POS真实数据形式,引入传统光学摄影测量的外方位元素,提出了基于倾角误差的MIMO下视阵列SAR误差补偿方法。该方法首先在三维空域补偿与波束无关的相位误差;其次将补偿后的回波数据变换到航迹向-跨航向二维波数域,并沿航迹向和跨航向均匀分为M和N段,获得MN个子块,每个子块补零并扩展到原尺寸后,将回波变换到航迹向-跨航向二维空域、距离向波数域,补偿与波数相关的相位误差;再次转换到三维空域,把每个子块补偿的数据直接相加,得到最终回波;最后使用三维RD成像算法得到聚焦正确的三维成像结果。通过仿真试验验证了方法的有效性。

Combined with the real POS data form,elements of exterior orientation of traditional optical photogrammetry were introduced,and inclination angle error compensation methods of MIMO downward-looking array SAR were designed.The beam-independent phase error was compensated in the three-dimensional spatial domain firstly.Then the compensated echo data was transformed into the two-dimensional wavenumber domain in along-track and cross-track directions,and was equally divided into M and N segments.The MN subblocks were zeroed and extended to the original size,transformed into the two-dimensional spatial domain in along-track and cross-track directions and wavenumber domain in range direction,and the beam-dependent phase error was compensated.Then,the subblock echo data were transformed into three-dimensional spatial domain,and added directly to the final data.Finally,the correct 3D imaging results could be obtained by 3D RD imaging algorithm.The effectiveness of the proposed method was verified by simulation experiments.