Ground moving target imaging and motion parameter estimation using radon-second-order WVD transform

For a SAR system with a moving target, long synthetic aperture time may greatly improve the SAR imaging quality, whereas defocusing may occur due to the range cell migration (RCM) and Doppler frequency migration (DFM) effects. To address those issues, a key procedure is to perform the accurate motion compensation, and then, the motion parameter estimation becomes essential. In this paper, a novel motion parameter estimation method named Second-order WVD (SoWVD) transform is proposed, which can achieve motion parameter estimation by 2-D Fourier transform (FT) instead of the exhaustive search of the trajectory slope in time-frequency plane by Wigner-Hough transform (WHT). In the sequel, a new SAR imaging method based on a combined Radon-SoWVD transform is developed, which can simultaneously eliminate the RCM and DFM effects without the restriction of Doppler ambiguity. After compensating target motion effect according to the estimated motion parameters, a ground moving target can be finely imaged. Real data processing results are provided to demonstrate the validity of the proposed imaging method.