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反投影(BP)算法是一类经典的合成孔径雷达(SAR)成像处理方法。BP在已知航迹条件下可以实现数据的高精度聚焦。但是,BP重建图像中,运动误差导致的目标散焦通常沿着不同的方向存在,残留距离徙动不能严格限制在一个距离分辨率单元内,运动补偿困难。文中提出了一种修正投影栅格的子带宽相位梯度自聚焦(PGA)处理方案。其中,基于数据采集平面的非均匀栅格重建图像,完全去除了目标散焦方向的空变特性。然后,对子带宽分解的反投影数据进行PGA运动补偿并拼接得到全分辨率图像。最后,点目标仿真验证了该方法的有效性。
Backprojection (BP) algorithm is a classic class of synthetic aperture radar (SAR) imaging processing methods. BP in the known track conditions can achieve high-precision data focus. However, in BP reconstruction images, the target defocus caused by the motion error often exists in different directions. The residual distance migration can not be strictly limited to a distance resolution unit, and the motion compensation is difficult. In this paper, a sub-bandwidth phase-gradient self-focusing (PGA) scheme is proposed to correct the projection grid. Among them, the non-uniform grid reconstruction image based on the data acquisition plane completely removes the air-gap characteristic of the target defocus direction. Then, PGA motion compensation and splicing are performed on the back-projection data of the sub-bandwidth decomposition to obtain a full-resolution image. Finally, point-target simulation verifies the effectiveness of this method.