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受运动参数测量误差和大气扰动等因素影响,合成孔径雷达(SAR)图像通常会发生散焦,利用自聚焦对散焦的SAR图像进行后处理是一种有效的重聚焦手段。传统的自聚焦算法都只是针对方位一维相位误差的估计和补偿。随着成像分辨率的提高,自聚焦时残留距离徙动的校正成为SAR成像面临的一个新挑战。本文推导得到了极坐标格式算法处理后残留距离徙动和方位相位误差的解析表达式,分析了两者之间的内在关系,并利用该关系,提出了一种能够同时进行残留距离徙动和方位相位误差补偿的两维自聚焦算法。实测数据处理结果表明,在残留距离徙动效应不可忽略的条件下,该方法能够极大地改善原有自聚焦算法的聚焦性能。
Due to measurement error of movement parameters and atmospheric disturbance, synthetic aperture radar (SAR) images usually defocus, and post-processing of defocused SAR images by self-focusing is an effective refocusing method. The traditional self-focusing algorithms are only for the azimuth one-dimensional phase error estimation and compensation. As imaging resolution increases, the correction of residual distance migration during self-focusing becomes a new challenge for SAR imaging. In this paper, we derive analytical expressions of residual distance migration and azimuth phase error after processing polar coordinate format algorithm, and analyze the intrinsic relationship between the two. Based on the relationship, we propose a method that can simulate the residual distance migration and Two - dimensional self - focusing algorithm of azimuth phase error compensation. The experimental results show that this method can greatly improve the focusing performance of the original self-focusing algorithm under the condition that the residual distance migration can not be neglected.