An Azimuth-Variant Autofocus Scheme of Bistatic Forward-Looking Synthetic Aperture Radar
An Azimuth-Variant Autofocus Scheme of Bistatic Forward-Looking Synthetic Aperture Radar
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DOI：
10.1109/lgrs.2017.2671879
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发表时间：
2017-03
影响因子：
4.8
通讯作者：
Wenchao Li;Junjie Wu;Yulin Huang;Jianyu Yang;Haiguang Yang
中科院分区：
文献类型：
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作者：
Wenchao Li;Junjie Wu;Yulin Huang;Jianyu Yang;Haiguang Yang
在双基地前视合成孔径雷达（BFSAR）中，当距离走动在方位时域进行补偿时，传统的自聚焦算法不能准确估计相位误差。该问题的根源在于方位时域线性距离徙动校正后的方位多普勒系数的影响。原则上，可以执行非线性线性调频缩放处理以去除方位角方差。然而，由于运动误差引起的多普勒参数的多普勒方位变化没有被考虑，最终的图像将出现严重的散焦。为了科普这个问题，提出了在BFSAR常规自动聚焦之前进行估计-评估-均衡的方案。与传统的自动聚焦方法不同，在自动聚焦之前额外地估计和均衡方位变化的多普勒系数，因此，可以精确地估计相位误差。BFSAR数据处理结果验证了该方法对改善BFSAR自聚焦的有效性。
In bistatic forward-looking synthetic aperture radar (BFSAR), conventional autofocus algorithms cannot estimate the phase errors accurately when the range walk is compensated in the azimuthal time domain. This problem stems from the influence of the azimuth-variant Doppler coefficients after linear range cell migration correction in azimuthal time domain. In principle, nonlinear chirp scaling processing can be carried out to remove the azimuth variance. Nevertheless, Doppler azimuth variations of the Doppler parameters induced by the motion errors are not taken into consideration and serious defocus would emerge in the final image. To cope with such a problem, an estimation–evaluation–equalization scheme is proposed before conventional autofocus for BFSAR. Different from the conventional autofocus method, the azimuth-variant Doppler coefficients are additionally estimated and equalized before autofocus, and as a consequence, phase errors can be precisely estimated. The BFSAR data processing results demonstrate the validity of the proposed method on the improvement of autofocus in BFSAR.