Sparse Flight 3-D Imaging of Spaceborne SAR Based on Frequency Domain Sparse Compressed Sensing

The space-borne Synthetic Aperture Radar (SAR) sparse flight three-dimensional (3-D) imaging technology through the multiple observations in cross-track direction obtains the 3-D spatial distribution of the observed scene. In this paper, the orbit distribution of single satellite SAR sparse flight is given. In order to shorten effectively the satellite revisit time, the formation of double star SAR orbit distribution is given. The corresponding cross-track equivalent aperture length is 20 km. A sparse 3-D imaging method based on interferometry and compressed sensing is proposed. The referential complex image is formed by using part of the echoes of the sparse flight, and the SAR 3-D image signals which are to be reconstruct are processed by interferometry. This method makes the signal sparse in the frequency domain. Under the large orbit distribution range, the frequency domain range direction and cross-track linear measurement matrix is established, which is beneficial to the Compressed Sensing(CS) theory to solve jointly the image frequency spectrum under sparse representation, and avoid the echoes coupling between the range and cross-track direction. Inversely transforming the resulting spectrum into the spatial domain, the reconstruction result can be obtained. Simulation results show that under the condition of sparse sampling rate of 74.4%, the imaging performance of the proposed method is still comparable to that of full sampling.