双基地SAR动目标图像相位误差分析和二维稀疏重聚焦处理

MTs phase error analysis in bistatic SAR imagery and two-dimensional sparse-based refocus

双基地合成孔径雷达(Synthetic Aperture Radar,SAR)系统中,数据采集空间几何关系复杂,动目标回波距离徙动严重,重建图像中往往存在几何失真和散焦现象,需要进一步补偿运动相位误差。为此,分析并推导了双基地动目标极坐标格式图像的二维相位误差谱。根据相位误差模型建立字典,约束动目标回波谱在字典上的投影系数,进而实现杂波和动目标能量的分离和重聚焦成像。点目标仿真验证了算法的有效性。

In the system of bistatic synthetic aperture radars(SARs),the range cell migration of the moving targets is increased significantly due to the complex data collection geometry,resulting in geometry distortion and smearing in the derived imagery.It is essential to compensate for the motion phase error of MTs.This paper derives the two-dimensional phase error of MTs in bistatic polar formatted imagery.Based on the obtained equation,an over-complete dictionary is built and the spectrum of bistatic imagery is viewed as a sparse representation of the dictionary.The sparse constraint is used to restrain the projection coefficients of the sparse representation and to promote the separation of clutter and refocus of MTs.Finally,the point target simulation verifies the effectiveness of the algorithm.