Towards the Retrieval of 2-D Vessel Velocities with Single-Platform Spaceborne SAR: Experimental Results with the TerraSAR-X 2-Looks TOPS Mode

Abstract

In this contribution, we propose the use of 2-looks Synthetic Aperture Radar data to retrieve azimuth velocities of moving targets with a single platform. The established technique to retrieve velocities of moving targets is Along-track Interferometry (ATI), which provides a measurement of the velocity in the radar line of sight direction by employing two or more phase centers separated in the along-track direction. The use of 2-looks data allows to observe targets at two different instants of time, with a Doppler separation, enabling the retrieval of the target velocity in the azimuth direction. We introduce the 2-looks Terrain Observation by Progressive Scans (TOPS) mode, presenting the performance that can be achieved with the TerraSAR-X system. Moreover, we present experimental results with real data acquired with TerraSAR-X over coastal areas to retrieve velocities of vessels. A validation of the results with Automatic Identification System (AIS) data (ground truth) provides accuracies below 1 m/s.