基于去调频技术的斜视聚束SAR成像方法

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.

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

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.Based 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,based on the squinted SAR 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) algorithm 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.