Unambiguous Reconstruction for Multichannel Nonuniform Sampling SAR Signal Based on Image Fusion

Multichannel signal processing in azimuth is a vital technique to enable a wide-swath Synthetic Aperture Radar (SAR) with high azimuth resolution. However, the multichannel high-resolution and wide-swath (HRWS) SAR system always suffers from the problem of the azimuth nonuniform sampling resulting in the image ambiguity, when it does not satisfy the uniform sampling condition. In this paper, to suppress the azimuth image ambiguity, we propose a novel unambiguous reconstruction method based on image fusion. During this reconstruction processing, the Back Projection (BP) algorithm is first utilized for SAR imaging to obtain the designed sub-images. Then, the reconstruction expression is derived as the summation of the sub-images weighted by the interpolation coefficient. This method integrates the reconstruction into the imaging process and the image fusion makes the procedure simple. In addition, the interpolation period, which affects the reconstruction image quality and efficiency, is further analyzed. Moreover, as the curved trajectory platform brings more challenges for the unambiguous reconstruction, the performance of the proposed method applied to the curved trajectory platform is studied. Finally, experimental results clearly verify the effectiveness of the proposed method for ambiguity suppression and demonstrate its applicability to the curved trajectory.