Research on Ship Positioning for Spaceborne SAR based on WVD

Spaceborne synthetic aperture radar plays a crucial role in marine target detection due to its ability to image such targets and perform all-time, all-weather surveillance. However, when the ship is moving, the imaging results will be offset in azimuth due to radial velocity. In order to correct the offset and restore the exact position of the ship, a large number of methods were proposed to correct the offset by estimating the radial velocity. In this paper, the idea of using the signal energy center to directly estimate the real azimuth position of the target is adopted, by using the Wigner-Wiley distribution(WVD) as a time-frequency transformation method to process signal from the range gate where the target is located, the energy center of the signal is estimated, resulting in accurate positioning and motion state estimation of the ship. The simulation results show that the proposed method has high estimation accuracy and strong robustness, even if the SNR reaches 14 dB, it can still accurately position ships(error within 50 m). Moreover, it has the potential of iterative calculation to improve the estimation accuracy.