基于稀疏字典分解的窄带雷达自旋目标干涉三维成像

空间微动目标干涉三维成像技术研究中，最关键的是对各散射点进行保相分离。当脉冲重复频率（PRF）不满足奈奎斯特采样定律时，基于图像处理的成像方法无法有效分离目标各散射点。提出了一种基于稀疏字典分解的窄带雷达自旋目标干涉三维成像方法，该方法能够直接从回波数据中分离出各散射点。首先，根据自旋目标回波信号特性构建稀疏字典，利用稀疏分解算法分解回波，得到各散射点子回波，其次通过时频分析并利用其保相性，获得各散射点的微动曲线，并提取出它们在时频平面上经过位置的干涉相位差，最后根据干涉相位差与坐标之间的关系重构散射点坐标，对空间自旋目标进行三维成像。仿真结果表明，在PRF不小于0.25倍奈奎斯特频率时，所提方法均能有效实现自旋目标三维成像。

Three-Dimensional Interferometric Imaging of Spinning Space Target Based on Sparse Dictionary Decomposition in Low-Resolution Radar

What is the most important is to separate the scatterers and keep their own phases simultaneously in the research of three-dimensional (3D) interferometric imaging for space micro motion target, however, when the pulse repetition frequency (PRF) does not satisfy the needs of the Nyquist Sampling Theorem, the image processing based method can''t effectively separate the scatterers. Therefore, a 3D interferometric imaging method based on sparse dictionary decomposition is proposed. The method can be used to separate each of the scatterers from echo data directly. First of all, according to the characteristics of target echo signal, an over-complete sparse dictionary is constructed, and then the echo is decomposed by using sparse decomposition algorithm to get the sub-echoes of each scatterer. Secondly, by means of time-frequency analysis and its performance of phase preservation, the micro motion curves of each scatterer are obtained, and the interferometric phase differences in the time-frequency plane are extracted. Finally, according to the relationship between interference phase differences and coordinates, the 3D imaging of space spinning target is constructed. The simulation results show that when PRF is greater than 0.25 times of Nyquist frequency, the proposed method can effectively achieve the 3D imaging of space spinning target.