在现有单通道圆形航迹合成孔径雷达(SAR)数据采集条件下,直接三维成像后高度向分辨性能受限。为此,文中研究了先进行二维处理后高度向分离成像的处理流程,提出了一种基于联合稀疏约束的单通道圆形航迹SAR 三维成像处理算法。首先,对传统二维成像中目标高度失配引入的相位误差进行了分析和推导。然后,计算不同位置处成像栅格的失配相位误差来构建过完备字典,并将二维成像处理后的雷达回波频谱在字典上进行联合稀疏约束投影。由于目标的失配相位误差与字典中各个向量之间的相干性存在差异,回波频谱的绝大部分能量会投影与其高度相匹配的字典向量位置处。结合联合稀疏约束计算则有助于实现回波投影能量的聚集和交叉分量的抑制,进而完成混合接收数据的分离和聚焦处理。最后,数值仿真验证了算法的有效性。

In the single channel circular synthetic aperture radar (SAR) system, the resolution in altitude dimension is limited severely. To solve this problem, a three dimensional(3D) imaging algorithm based on the joint sparse constraint, which consists of the two-dimensional(2D) processing followed by the separated imaging in the elevation dimension, is proposed in this paper. Firstly, the phase error introduced by the mismatched height in traditional 2D imaging is analyzed and deduced. Then, the mismatched phase errors of imaging grids at different locations are calculated to build an over-complete dictionary, and the spectrum of the processed radar data is projected on the dictionary based on the joint sparse constraint. Since the coherence relationships between the phase error of targets and the vectors in the dictionary are different, most of the energy of the spectrum will be projected on the positions corresponding with the matched height in the dictionary. The joint sparse constraint can realize the aggregation of projection energy and the suppression of cross components, thus implementing the separation of mixed received data and focus processing of targets with different heights. Finally, numerical simulation verifies the effectiveness of the algorithm.

TN953

国家自然科学基金资助项目(61801232)