一种基于极坐标格式算法的高分辨SAR成像自聚焦算法  

Autofocus Algorithm of High Resolution SAR Based on Polar Format Algorithm Processing

作　　者：曾乐天[1] 梁毅[1] 邢孟道[1] 

机构地区：[1]西安电子科技大学雷达信号处理国家重点实验室,西安710071

出　　处：《电子与信息学报》2015年第6期1409-1415,共7页Journal of Electronics & Information Technology

基　　金：中央高校基本科研业务费专项资金(K5051302046);国家自然科学基金优秀青年基金(61222108)资助课题

摘　　要：针对机载聚束合成孔径雷达(SAR)惯导精度无法满足高分辨SAR成像的问题,该文提出了一种结合极坐标格式算法(PFA)的自聚焦算法,即"由粗到精"的混合多阶段参数化最小熵(Hybrid Multistage Parameterized Minimum Entropy,HMPME)距离单元徙动校正方法和基于图像对比度增强(Contrast Enhancement,CE)的变步长迭代相位误差校正方法。该自聚焦算法可以直接嵌入到PFA处理中,精确地补偿了惯导测量精度不足引起的越距离单元徙动(Range Cell Migration,RCM)和相位误差,且对于低对比度、低信噪比场景数据有良好的聚焦性能。最后,利用仿真实验和实测机载聚束SAR数据验证了所提算法的有效性。Equipped with an airborne spotlight SAR, inertia navigation system can not measure the motion errors with the required accuracy for high resolution SAR imaging, which may degrade severely the quality of a SAR image. In this paper, a novel autofocus algorithm that can be directly embedded in Polar Format Algorithm （PFA） is proposed, that is, a Hybrid Multistage Parameterized Minimum Entropy （HMPME） algorithm to proceed Range Cell Migration （RCM） correction and a scaled-stepsize iterative phase correction method based on Contrast Enhancement （CE）. The autofocus processing accurately compensates the effects of range cell migration and phase errors. Also, this algorithm is most robust in processing images of low contrast and low signal-to-noise ratio. Finally simulations and experiments with real spotlight SAR data validate the effectiveness of the proposed algorithm.

关 键 词：合成孔径雷达 极坐标格式算法 自聚焦 参数化最小熵 对比度增强 

分 类 号：TN957.52[电子电信—信号与信息处理]