A Fast Time-Domain SAR Imaging and Corresponding Autofocus Method Based on Hybrid Coordinate System
A Fast Time-Domain SAR Imaging and Corresponding Autofocus Method Based on Hybrid Coordinate System
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DOI：
10.1109/tgrs.2019.2921917
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发表时间：
2019-07
影响因子：
8.2
通讯作者：
Yi Liang;Guofei Li;Jun Wen;Gang Zhang;Yanfeng Dang;M. Xing
中科院分区：
文献类型：
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作者：
Yi Liang;Guofei Li;Jun Wen;Gang Zhang;Yanfeng Dang;M. Xing
与频域算法相比，时域算法（TDA）可以实现任意轨迹和大积分角条件下的图像聚焦。然而，快速TDA的坐标变换需要在距离和方位角方向上进行插值，这不可避免地增加了计算量并引入插值误差。本文提出了一种基于混合坐标（HC）系统的快速时域成像和相应的自动对焦方法。首先，在快速TDA过程中对插值操作进行了优化。它将二维插补转换为仅在方位角方向上的一维插补，提高了执行效率并减少了插补误差。接下来，研究了基于高斯-牛顿迭代的 3-D 轨迹偏差估计方法，用于 HC 系统中的运动补偿。通过迭代优化，准确估计飞行过程中的3D运动误差，并精确补偿空变相位误差。该方法具有良好的鲁棒性和普适性。仿真结果和实际数据处理验证了本文方法的有效性和实用性。
Compared with frequency-domain algorithms, time-domain algorithms (TDAs) can achieve image focusing under the conditions of arbitrary trajectories and large integration angles. However, the interpolations in both range and bearing angle directions are required in the coordinate transformation of fast TDAs, which inevitably increases the computational load and introduces interpolation errors. In this paper, a fast time-domain imaging and corresponding autofocus method based on the hybrid coordinate (HC) system is proposed. First, the interpolation operation is optimized in the process of fast TDAs. It transforms the 2-D interpolation into 1-D interpolation only in the bearing angle direction, which improves the execution efficiency and reduces the interpolation error. Next, a 3-D trajectory deviation estimation method based on Gauss–Newton iteration is investigated for the motion compensation in the HC system. By iterative optimization, the 3-D motion errors during the flight are estimated accurately, and the space-variant phase error is compensated precisely. This method has good robustness and universality. Simulation results and real data processing demonstrate the effectiveness and the practicability of the method presented in this paper.