Orbit accuracy estimation by multi-squint phase: First Sentinel-1 results

In this paper, we propose a model-based procedure to estimate the accuracy of Sentinel-1 orbit products by the Multi-Squint (MS) phase. The technique exploits the results of single baseline MS analyses collected for each possible master and slave combination in a stack to estimate the absolute orbit error. Accordingly, as first step we state the geometric model of the InSAR phase and the MS phase model as derivative of the In-SAR phase geometric model with respect to the squint angle, then we describe the algorithm to estimate two components of baseline error using the theoretical model. In this paper we focus on the TOPSAR acquisition modes of Sentinel-1 assuming at the most a linear error in the known slave trajectory. In particular, we describe a dedicated methodology to measure baselines accuracy using bursts and swaths overlaps in data acquired by IW and EW acquisition modes. Finally, we suggest a technique to estimate, by a weigthed least-squase inversion, the absolute orbit error of each image in a stack. Experimental results of single and multi-baseline MS analysis obtained on Sentinel-1 data will be displayed.