Résumé
This study addresses the effects of SAR signatures of moving vessels extracted from Sentinel-1 imagery, that suffer from a loss of focus due to the azimuthal velocity, e.g. target defocusing. The effects generated by SAR moving targets in the azimuthal direction result in residual Doppler chirps that can be estimated and characterized by processing Sentinel-1 Single Look Complex (SLC) images. We propose to employ the fractional Fourier transform (FrFT) in order to compensate the moving target defocusing effects in the SLC domain. In addition, different Sentinel-1 polarimetric representations of a target within the FrFT domain are also addressed and fused. The experimental results are based on Sentinel-1 Stripmap images and are cross compared with AIS data.