一种基于图像后处理的极坐标格式算法波前弯曲补偿方法  

Image Domain Space-variant Post-processing for Wavefront Curvature Correction in Polar Format Spotlight SAR Image

作　　者：毛新华[1] 朱岱寅[1] 叶少华[2] 朱兆达[1] 

机构地区：[1]南京航空航天大学信息科学与技术学院,江苏南京210016 [2]中国雷华电子技术研究所,江苏无锡214063

出　　处：《电子学报》2010年第1期244-250,共7页Acta Electronica Sinica

基　　金：国家自然科学基金(No.60502030);航空科学基金(No.20080152004);教育部博士点基金(No.20070280753);中国博士后基金(No.20090461119)

摘　　要：极坐标格式算法(PFA)波前弯曲误差分析是对波前弯曲进行有效补偿的基础,以往波前弯曲误差推导过程中都对差分距离采用了二阶近似,在对大场景范围进行近场、高分辨率成像时已不能满足要求.本文采用新的方法对波前弯曲误差进行了精确的推导,得到了波前弯曲误差在空间频域的二阶泰勒展开表达式.利用推导的波前弯曲误差公式,在PFA图像域通过空变滤波和几何失真校正分别对二次和一次相位误差进行补偿,极大地改善了波前弯曲对PFA成像场景大小的限制.最后通过仿真数据处理验证了分析结果.The polar format algorithm（PFA） for spotlight synthetic aperture radar（SAR） is based on the assumption of strictly planar wavefronts.Thus,the realistic wavefront curvature introduces phase error terms which cause space-variant geometric distortion and defocus on the formed imagery.In previous study,all the analysis on phase error induced by wavefront curvature is based on the second order approximation of the differential range.It still can＇t meet the required precision when imaging very large scenes at close range with high resolution.In this paper,a generalized squint mode 3D imaging geometry is considered to derive the phase history expression in wavenumber domain with consideration of the accurate differential range.Based on the phase model derived,image domain post-processing steps,including space-variant filtering and geometric distortion correction,are employed to compensate the quadratic and linear phase error terms.Simulation results validate the theoretical analysis.

关 键 词：合成孔径雷达 极坐标格式算法 波前弯曲 空变滤波 几何失真校正 

分 类 号：TN57[电子电信]