一种超高分辨率机载聚束SAR两维自聚焦算法  

2-D Autofocus Algorithm for Ultra-high Resolution Airborne Spotlight SAR Imaging

作　　者：毛新华[1] 朱岱寅[1] 朱兆达[1] 

机构地区：[1]南京航空航天大学电子信息工程学院,江苏南京210016

出　　处：《航空学报》2012年第7期1289-1295,共7页Acta Aeronautica et Astronautica Sinica

基　　金：国防基础科研计划(B2520110008);国家自然科学基金(61071165);航空科学基金(20102052024);中国博士后科学基金特别资助(201003586);教育部"新世纪人才支持计划"(NCET-09-0069);中央高校基本科研业务费专项资金(NS2012097)~~

摘　　要：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。Synthetic aperture radar （SAR） images are often blurred by phase perturbations induced by uncompensated sen- sor motion and/or unknown propagation effects caused by turbulent media. To get refocused images, autofocus proves to be useful post-processing technique applied to estimate and compensate the unknown phase errors. However, an important drawback of the conventional autofocus algorithms is that they are able to compensate for only one-dimensional azimuth phase errors. As the resolution increase, residual range cell migration, which makes the defocus inherently two-dimensional （2-D）, becomes a new challenge. In this paper, the analytical relationship between the residual range cell migration and az- imuth phase error in polar format imagery is developed. Utilizing this relationship, a 2-D autofocus algorithm that can simul- taneously compensate for the residual range migration and azimuth phase error is proposed. The results of real data process- ing validate the effectiveness of the proposed method.

关 键 词：合成孔径雷达 超高分辨率成像 自聚焦 残留距离徙动 方位相位误差 

分 类 号：V243.2[航空宇航科学与技术—飞行器设计] TN958[电子电信—信号与信息处理]