基于修正均匀冗余阵列正反编码的稀疏阵列SAR下视三维成像处理

Downward-looking 3D Imaging Processing of Sparse Array SAR Based on Modified Uniformly Redundant Arrays Positive and Negative Coding

该文研究基于频分正交信号的机载交轨稀疏阵列SAR下视3维成像问题。为解决孔径综合方法带来的重复频率高、数据冗余量大和运动补偿等问题,提出一种基于修正均匀冗余阵列(Modified Uniformly Redundant Arrays,MURA)编码和干涉处理频域稀疏的3维成像方法,直接在距离频域稀疏采样条件下对目标场景进行下视3维成像。引入MURA编码对回波数据在阵列采样平面进行正反编码调制,分别获得两幅3维复图像,并通过干涉处理使信号3维频谱集中在低频段,利用频域低通滤波或压缩感知(Compressed Sensing,CS)实现目标场景3维成像。该方法具有回波数据利用率高和工作重复频率低的特点。仿真分析和试验数据验证了方法的有效性。

The three-dimensional （3D） imaging of airborne sparse array SAR is studied. In order to avoid data redundancy, high Pulse Repetition Frequency （PRF） and motion compensation caused by aperture synthesis, the Modified Uniformly Redundant Arrays （MURA） is introduced for random modulation on echo data along the array antenna sampling plane. The MURA positive and negative coded echo signals are processed to form 3D complex images, respectively, and by interferometry of two images the 3D frequency spectrum of the signal is concentrated in low frequency band. Therefore, using low-pass filter or Compressed Sensing （CS） processing in frequency domain, 3D image with sufficient performance is obtained under the condition of sparse sampling in the frequency domain. The method has the characteristics of high utilization rate of echo data and low repetition frequency of the system. Simulation results and experimental data of the anechoic chamber verify the effectiveness of the proposed method.