Along-track velocity estimation for SAR moving target in complex image domain

A new along-track velocity estimation method is proposed for synthetic aperture radar (SAR) ground moving target in the complex image domain. For a target with relatively large along-track velocity, its complex response is a linear frequency-modulated (LFM) signal in the image domain. Its Doppler rate is mainly determined by the along-track velocity, while the effect of the cross-track velocity can be ignored. In this paper, the along-track velocity of a detected target in the image domain can be estimated based on the Doppler rate retrieval via fractional Fourier transform. The proposed method can be well combined with the SAR-GMTI algorithms in image domain, where the signal to clutter-plus-noise ratio is higher than other domains. Finally, some results of numerical experiments are provided to demonstrate the effectiveness of the proposed method.