Imaging and locating multiple ground moving targets based on keystone transform and FrFT for single channel SAR system

Synthetic aperture radar (SAR) imaging techniques have been successfully developed for static ground targets, but if the moving target returns are processed in the conventional imaging way, the resulting SAR image of moving targets will appear blurred and be misplaced in azimuth direction. In this paper, we proposed a method which is based on keystone transform and fractional Fourier transform (FrFT) to solve these problems. Firstly, first order keystone transform is performed on range compression results to correct range walk, then estimates of Doppler Centroid and Doppler modulation rate are obtained by using fractional Fourier transform, finally focused image of multiple moving targets is achieved by making use of the Doppler estimates. It can ascertain initial positions of multiple moving targets; moreover, it can estimate azimuth velocity, radial velocity and radial acceleration for every moving target. The simulation results show that this method can image and locate multiple ground moving targets effectively.