First results of TanDEM-X along-track interferometry

The interferometric imaging modes of the TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurements) satellite formation offer improved along-track interferometric capabilities e.g. through longer and multiple baselines. While the first provide high sensitivities to ground motions, the latter enable to resolve ambiguities. The extraction of motion information from TanDEM-X data by means of ATI is challenging due to the hybrid nature of the interferometric baseline. This is generally composed of an across-track (XTI) and an along-track interferometric (ATI) component B_ATI and requires a separation of the respective interferometric phase contributions.