Joint Estimation of Doppler Parameters for SAR with Large Range Migration

By exploiting the statistical property of synthetic aperture radar (SAR) range-Doppler domain signal, a novel approach is proposed in this paper to solve the dilemma whether it is better to first estimate Doppler parameter or to determine range migration (RM) trajectory. The approach is performed in the range compressed range-Doppler domain. Its basic idea is to search for the ambiguity number m_opt and platform velocity v_opt which minimize the contrast of the sequence made up of the signal intensity distributed over the RM trajectory determined by them. The better auto-focus performance can be obtained from the data aligned according to the RM trajectory determined by them. The better auto-focus performance can be obtained from the data aligned according to the RM trajectory determined by m_opt and v_opt and furthermore, the correct PRF-ambiguity number can also be computed, accordingly