Decorrelation effects in bistatic TanDEM-X data

The TanDEM-X mission comprises two nearly identical satellites: TerraSAR-X and TanDEM-X. The primary objective of the mission is the generation of a worldwide and consistent digital elevation model (DEM) with an unprecedented accuracy. The two satellites fly in a close orbit configuration and act as a large single-pass radar interferometer with the opportunity for flexible baseline selection, allowing the acquisition of highly accurate cross- and along-track interferograms [1]. One of the key parameters in estimating interferometric performance is the coherence γ. Several error sources may contribute to a coherence loss: in this paper, the impact of limited signal-to-noise ratio (SNR), volume decorrelation, and quantization errors are investigated in detail. Furthermore, a novel azimuth-switched quantization (ASQ) technique is introduced and a preliminary performance assessment is presented.