A Novel Back-Projection-Based Target Motion Parameter Estimation Scheme for Dual-Channel SAR

Due to the reduction of imaging accuracy caused by the approximations of signal models, traditional synthetic aperture radar (SAR) moving target motion parameter estimation methods based on frequency-domain imaging algorithms may suffer from the problem of accuracy reduction. To solve this problem, a novel moving target motion parameter estimation scheme is proposed for dual-channel SAR based on the time-domain back-projection (BP) algorithm. First, the BP imaging model of a moving target is constructed for the dual-channel SAR, and the focus position and the phase response of the moving target are analyzed. We show that the radial velocity of the moving target is proportional to the center frequency of the azimuth wavenumber spectrum, which can be used to estimate the radial velocity. Afterward, the displaced phase center antenna based on BP is deduced for the clutter suppression, and the constant false alarm rate detector is used to detect moving targets. Then, the azimuth offset of the moving target between the two subaperture images is used to estimate the azimuth velocity since it is proportional to the azimuth velocity. Meanwhile, a modified refocusing method is applied for a more accurate azimuth-velocity estimation. Furthermore, the slant-range velocity is calculated by the geometric relationship among the radial velocity, azimuth velocity, and the slant-range velocity. The simulation and semiphysical simulation experiments verify that the proposed scheme can achieve higher accuracy in motion parameter estimation than the method based on the frequency-domain imaging algorithm in both the side-looking and squint-looking dual-channel SAR.