基于去调频技术的斜视聚束SAR成像方法  

A novel approach based on deramping technique for the squinted spotlight SAR imaging

作　　者：安道祥[1] 李欣[1] 黄晓涛[1] 周智敏[1] 

机构地区：[1]国防科学技术大学电子科学与工程学院,长沙410073

出　　处：《中国科学：信息科学》2012年第2期220-236,共17页Scientia Sinica(Informationis)

基　　金：教育部新世纪优秀人才支持计划(批准号:NCET-07-0223;NCET-10-0895);国家自然科学基金(批准号:60972121);全国优秀博士学位论文作者专项资金资助项目(批准号:201046);湖南省研究生科研创新项目(批准号:CX2009B009)资助

摘　　要：针对具有方位谱混叠现象的斜视聚束式合成孔径雷达(SAR)成像问题,本文研究了一种基于去调频技术的成像方法.文中首先分析了斜视聚束SAR中的方位谱混叠现象,从理论上找出了斜视角影响方位粗聚焦的根本原因.基于分析结果,引入了回波信号非线性相位校正预处理法,彻底消除了斜视角的影响,从而得到正确的粗聚焦结果.然后基于斜视成像模型,推导了预处理回波信号的方位粗聚焦和精聚焦处理过程.在精聚焦的方位滤波处理中,针对非线性相位校正预处理导致的场景聚焦深度限制问题,提出了一种改进的非线性调频变标(NLCS)算法,实现了回波信号的高精度方位压缩.仿真实验结果证明了文中理论分析的正确性和所提方法的有效性.This paper presents an imaging algorithm based on the deramp processing technique to resolve the imaging problem of the squinted spotlight synthetic aperture radar （SAR） in the presence of the azimuth spectrum folding phenomenon. First of all, we carried out the analysis of the azimuth spectrum folding phenomenon in squinted spotlight SAR, and found the reason for the squint angle impacts on the azimuth coarse focusing. Bused on the analysis result, a nonlinear phase correction preprocessing method is introduced, which can completely remove the influence of the squint angle on the azimuth coarse focusing, and the correct coarse focused result is obtained. Then, bused on the squinted SAP~ imaging model, the coarse focusing and precise focusing of the preprocessed echo data are deducted, respectively. In the azimuth matched filtering step of the precise focusing, a modified nonlinear chirp scaling （NLCS） Mgorithm is proposed for overcoming the azimuth depth of focus （ADOF） limitation problem, which is induced by the nonlinear phase correction preprocessing, and a high precise azimuth compression is achieved. Simulation experiment results prove the validity of the proposed algorithms.

关 键 词：斜视聚束SAR 方位谱混叠现象 非线性相位校正 聚焦深度 非线性调频变标 

分 类 号：TN958[电子电信—信号与信息处理]