Fast factorized backprojection (FFBP) takes advantage of high accuracy of time-domain algorithms while also possessing high efficiency comparable with conventional frequency domain algorithms. When phase errors need to be compensated for high-resolution synthetic aperture radar (SAR) imaging, however, neither polar formatted subimages within FFBP flow nor the final Cartesian image formed by FFBP is suitable for phase gradient autofocus (PGA). This is because these kinds of images are not capable of providing PGA with a clear Fourier transform relationship (FTR) between image domain and range-compressed phase history domain. In this paper, we make some essential modifications to the original FFBP and present a scheme to incorporate overlapped-subaperture frame for an accurate PGA processing. The raw data collected by an airborne high-resolution spotlight SAR are used to demonstrate the performance of this algorithm.

中文翻译：

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联合修正的快速分解背投影和自动对焦的高精度Spotlight SAR成像

快速分解反投影（FFBP）充分利用了时域算法的高精度，同时还具有与传统频域算法相当的效率。但是，当需要为高分辨率合成孔径雷达（SAR）成像补偿相位误差时，FFBP内的极性格式化子图像和FFBP形成的最终笛卡尔图像都不适合于相位梯度自动聚焦（PGA）。这是因为这些类型的图像无法为PGA提供图像域和范围压缩的相位历史域之间的清晰傅里叶变换关系（FTR）。在本文中，我们对原始FFBP进行了一些必要的修改，并提出了一种方案，该方案将重叠的衬托框架并入以进行精确的PGA处理。