Road-Aided Doppler Ambiguity Resolver for SAR Ground Moving Target in the Image Domain

A new Doppler ambiguity resolver (DAR) is proposed for ground moving targets of synthetic aperture radar (SAR) in the image domain. Based on the range-Doppler imaging of a static scene, the moving target's response is analyzed in the image domain, and the target's response slope is jointly determined by three motion parameters, i.e., azimuth velocity, ambiguous range velocity, and Doppler ambiguity number. A new DAR utilizing these three parameters is then proposed via the following steps. First, the moving target is detected after ground clutter cancelation between dual-channel images. Second, the ambiguous range velocity is estimated, and the road and its slope are extracted from the SAR image to establish the relationship between the 2-D velocities. Third, the Doppler ambiguity number is determined based on the response slope, the road slope, and the estimated ambiguous range velocity. Compared with the existing DARs in the 2-D time domain, the proposed algorithm works better in the most common signal-to-clutter-noise ratio scenarios. Finally, the results of the numerical experiments are provided to demonstrate the effectiveness of the proposed method.