Compressed sensing digital receiver and orthogonal reconstructing algorithm for wideband ISAR radar

Abstract

This paper proposes a novel design of intermediate frequency (IF) digital receiver for wideband inverse synthetic aperture radar (ISAR) based on compressed sensing (CS). For the convenience in engineering application, we use random sampling in the digital receiver and make it possible to digitize the wideband IF signal using a commercial off-the-shelf analog-to-digital converter with sub-Nyquist sample rate. Besides, a novel basis for the sparse representation of real-valued ISAR radar echoes is built in this paper, and an orthogonal CS reconstructing algorithm is proposed based on this. Using our proposed method, the complex-valued range profile of target can be directly reconstructed from the subsampled real raw echo. The phase information of target range profile, which is very important for the coherent processing in ISAR imaging, is well reserved during the reconstruction. As a result, the down converter and matched filter, which are essential in conventional radar receiver, can be eliminated in our CS digital receiver. A series of simulation validates our design and demonstrates the feasibility of the sub-Nyquist sampling. The simulation results of ISAR imaging verify the validity and superiority of the proposed orthogonal reconstructing method.

摘要

创新点

本文基于压缩感知理论针对宽带ISAR成像雷达提出了一种全新架构的数字接收机。 本系统采用利于工程实现的随机采样方法, 利用现有ADC芯片实现了对雷达回波信号低于奈奎斯特速率的欠采样。 此外, 本文提出一种正交重构算法, 能够从欠采样的实信号中重构复数的雷达目标一维距离像, 并在重构中较好的保留了回波的相位信息, 便于ISAR图像处理。 因此, 正交重构能够完美替代常规数字接收机中的数字下变频器和匹配滤波器, 极大简化接收机设计。 针对本文提出的设计和重构算法, 论文开展了一系列仿真实验, 实验结果证明了系统的可行性和正交重构算法的可靠性。