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超高分辨率条件下,机载合成孔径雷达(SAR)发射信号带宽大,合成孔径时间比较长,对成像处理算法的精度和效率要求较高。现有近似频率域处理和时间域滤波反投影(FBP)算法聚焦SAR数据时均存在诸多问题。基于微局部分析方法,提出了一种新颖的频率域滤波反投影(FD-FBP)成像处理方案。首先,利用Keystone变换简化了数据距离多普勒(RD)域徙动表达式。然后,在RD域进行反投影操作,对参考位置处反投影数据进行移位、相位补偿和FFT等操作即可以得到图像,从而在保证算法精确性的前提下有效降低了运算效率,实现了频率域方法的高效率和时间域方法的精确性特点的结合。最后,点目标仿真和实测数据处理以及与FBP等算法的对比验证了该方法的有效性。
Under the conditions of ultra-high resolution, SAR signal transmission bandwidth is large, and the synthetic aperture time is relatively long, which requires high precision and efficiency of the imaging processing algorithm. The existing approximate frequency domain processing and time domain filtering back projection (FBP) algorithms have many problems in focusing SAR data. Based on the micro-local analysis method, a novel frequency domain filtering back projection (FD-FBP) imaging processing scheme is proposed. First, the Keystone transform is used to simplify the data distance Doppler (RD) domain migration expression. Then, the back-projection operation is performed in the RD domain, and the image can be obtained by performing the operations such as the back-projection data at the reference position, the phase compensation and the FFT operation, thereby effectively reducing the computational efficiency under the premise of ensuring the accuracy of the algorithm, The combination of the high efficiency of domain methods and the accuracy of time domain methods. Finally, the point-target simulation and measured data processing and comparison with FBP and other algorithms verify the effectiveness of the proposed method.