An Integrated Interframe Stabilization and Fast Imaging Method for Video Synthetic Aperture Radar

Video image stability and imaging efficiency are two main problems in the application of current video synthetic aperture radar (ViSAR) systems. High resolution millimeter-wave ViSAR imaging is susceptible to inter-frame drift caused by motion errors, which seriously affects video stability. Image domain based registration algorithms would be affected by speckle noise, which causes distortions in synthetic aperture radar (SAR) images. Moreover, the high aperture overlapped rate in ViSAR results in redundant computations in multi-frame imaging. Therefore, how to achieve multi-frame fast imaging with high stability is a significant research direction of ViSAR. In this paper, a novel integrated method of fast multi-frame imaging and stabilization for video SAR is proposed. This approach mainly contains two aspects. First, in order to address video inter-frame drift compensation, the generating mechanism of drift error is analyzed from the imaging aspect. A gradient function is constructed to accurately estimate motion error by maximizing the correlation between sub-aperture images. Next, based on accurate frame motion error estimation, a sub-aperture complex-weighted fast back projection (SCFBP) algorithm is proposed, which combines the inter-frame motion error compensation in the signal domain. Simulations and real measured data experiments illustrate that the proposed method effectively improves the inter-frame stability and accelerates multi-frame imaging for video SAR.