A Novel Compressive Sensing-Based Multichannel HRWS SAR Imaging Technique for Moving Targets

摘要

When high-resolution wide-swath (HRWS) multichannel synthetic aperture radar (MC-SAR) system is used for ocean observation, vast amount of redundant data is generated, significantly limiting its applications. Though compressive sensing (CS)-based method has been applied to the traditional single-channel or dual-channel SAR imaging system, it is no longer applicable for MC-SAR due to the existence of channel error when using the space-time equivalent sampling technique for azimuth signal reconstruction. By analyzing such periodic channel error, i.e., frequency-dependence phase mismatch (FD-PM), in this article, a novel dictionary is constructed for CS-based HRWS MC-SAR imaging after an improved range cell migration correction method is applied. As a result, a novel CS imaging mode is proposed for the ocean moving target based on the sparsity of the target scattering centers, by which the amount of data in MC-SAR can be reduced by sampling below the Nyquist sampling rate and the swath width can be further increased. Experimental results show that the proposed method clearly eliminates the azimuth defocus and blur caused by low sampling rate and FD-PM, and significantly reduces the amount of data to about one-third when compared to sampling at the Nyquist rate.