Performance Evaluation of the TanDEM-X Quad Polarization Acquisitions in the Science Phase

Abstract:
The TanDEM-X mission consists of two SAR satellites flying in close formation with adjustable along- and cross-track baselines. The main objective of the mission is to acquire and generate a digital elevation model (DEM) of the complete Earth’s land surface with high accuracy and high resolution. As further objective, different experimental modes can be commanded and are intended for the investigation of new potential applications of SAR data. The TanDEM-X dual-receive antenna (DRA) mode allows the acquisition of experimental quad polarization data. Acquisitions in this mode have been systematically commanded during the TanDEM-X science phase between December 2014 and December 2015. Monostatic acquisitions with an along-track separation of 76 km and bistatic acquisitions with variable effective baselines from 150 m up to 4 km have been commanded for the first time within a spaceborne mission. This paper investigates the performance of the TanDEM-X full polarimetric products over the complete science phase. Main focus is given to the evaluation of SAR parameters such as resolution, signal-to-noise ratio (SNR), ambiguities, and quantization settings, and to the analysis of the resulting interferometric performance, with the investigation of quality parameters such as coherence and relative height error.