基于椭圆模型与改进NLCS的一站固定式大基线双站SAR成像算法  

Improved NLCS Algorithm Based on Ellipse Model for One-stationary Bistatic SAR with Large Baseline

作　　者：钟华[1] 胡剑[1] 张松[1] 孙闽红[1] ZHONG Hua HU Jian ZHANG Song SUN Minhong(School of Communication Engineering, Hangzhou Dianzi University, Hangzhou 310018, China)

机构地区：[1]杭州电子科技大学通信工程学院,杭州310018

出　　处：《电子与信息学报》2016年第12期3174-3181,共8页Journal of Electronics & Information Technology

基　　金：国家自然科学基金(61301248;61271214);中国航天科技创新基金~~

摘　　要：在一站固定式双站SAR成像处理中,该文针对距离-方位2维空变描述不够准确导致成像性能迅速下降的问题,提出一种新的椭圆模型精确描述一站固定式大基线双站SAR的距离-方位空变特性,并基于此推导了改进的非线性调频变标(NLCS)成像算法。在距离向,首先利用相位去斜完成距离去走动和多普勒中心矫正,接着对剩余距离单元徙动和距离方位高次耦合项进行了去除处理。在方位向,根据一站固定式双站SAR的2维空变特性,提出了一种用于描述回波距离-方位空变特性的椭圆模型,基于该模型对空变的回波方位调频率进行了分析,并重新推导NLCS算法的方位变标函数和方位压缩系数。理论分析与仿真结果证明,所提出的模型不仅揭示了一站固定式大基线双站SAR数据的2维空变特性,而且对回波的距离-方位空变给出了更精确的解析式描述,使得基于该模型改进的NLCS算法可以获得更好的成像处理效果。In One-Stationary Bistatic Synthetic Aperture Radar （OS-BiSAR） imaging, imprecise description of 2-D range-azimuth space-variant property usually leads to deterioration of final SAR image rapidly. In order to solve this issue, a new ellipse model is proposed to precisely describe range-azimuth space-variant property of OS-BiSAR with large baseline, and an improved Non-Linear Chirp Scaling （NLCS） algorithm is also derived based on this model. First, a phase de-ramp operation is performed to remove the linear Range Cell Migration （RCM） and Doppler centroid in range frequency domain. Then, the residual RCM and high order range-azimuth coupling terms are removed. Thirdly, a new ellipse model is established to describe range-azimuth space-variant property of OS-BiSAR, and then the azimuth frequency modulation rate of space-variant echo is analyzed. Moreover, azimuth scaling function of NLCS and azimuth compression factors are re-derived. Theoretical analysis and simulation results show that the proposed model not only reveals the property of 2-D azimuth-variant in OS-BiSAR, but also provides a precise analytical expression to depict the 2-D range-azimuth space-variant property of OS-BiSAR. Furthermore, simulation results validate that the improved NLCS algorithm based on this new model has high imaging performance.

关 键 词：SAR成像 双站SAR 一站固定式 非线性调频变标 椭圆模型 

分 类 号：TN957.52[电子电信—信号与信息处理]