Radial velocity estimation based on Radon transforms for SAR images of moving ground targets

With synthetic aperture radar (SAR), the radial velocity of a moving ground target may cause Doppler ambiguities and spectrum split, which seriously affect the detection and velocity estimates. A Radon transform (RT) based method was developed to efficiently resolve the Doppler ambiguities and spectrum split to obtain precise estimates of the Doppler centroid and radial velocity. First, the inclination angles of the range walk are determined for all possible ambiguity numbers based on the radar and platform parameters to project the ambiguity number to the inclination angle. Since the radial velocity is unknown, the RT for all prior angles are computed with the ambiguity number obtained by searching for the peak value. A Doppler spectrum detector is used to solve the spectrum split and to accurately estimate the baseband Doppler centroid using the energy balance approach. Numerical simulations demonstrate the effectiveness of this method. ©, 2015, Press of Tsinghua University. All right reserved.