Estimation of Ship Velocity by Adaptive Processing of Single Aperture RADARSAT-2 Data: Validation with AIS Data from the Strait of Gibraltar

Abstract : Adaptive processing of RADARSAT-2 synthetic aperture radar (SAR) imagery of known ships acquired near the Strait of Gibraltar provides estimates of the ship radial speed along the radar line of site and the ship aspect angle, which can be combined to provide an estimate of the ship velocity in the absence of a visible ship wake. Using a Doppler offset algorithm, it was found that the standard deviation of the radial speed estimates was 0.85 m/s for 26 ships in two HH scenes, compared to 0.3 m/s using along-track interferometry (ATI) algorithms, and was 1.3 m/s for 9 ships in a VV scene, compared to 0.6 m/s using ATI algorithms. It was shown that ship aspect angle estimation can be complicated by wave-induced ship motion, which can smear or change the orientation of the imaged ship signature. Validation was carried out against coastal-received Automatic Identification System (AIS) data. It is apparent that ship velocity estimation is feasible for single aperture SARs in the absence of a visible ship wake signature, which could be useful for tracking ships that are not transmitting AIS data.