On the Analysis of VLBI Observations to GNSS Satellites

Conference poster, 2014

Space geodetic techniques such as Very Long Baseline Interferometry (VLBI) and Global Navigation Satellite Systems (GNSS) are used for the determination of celestial and terrestrial reference frames and Earth orientation parameters. It is of utmost importance to combine the observations from the different techniques to fully exploit the strengths and unique characteristics of the techniques, however, inaccurate local ties are problematic for a rigorous combination. To improve the link between the techniques, tests are under way to observe GNSS signals with VLBI radio telescopes directly, and to observe GNSS signals in GNSS antennas with subsequent processing in the VLBI system (“GNSS-VLBI Hybrid System”) including VLBI correlation. In both cases, the GNSS data type is the difference between the ranges from two stations to a satellite. However, it is still difficult to acquire those observations and thus we apply post-processed range measurements from a precise point positioning (PPP) solution with the C5++ software to build those single differences which are then used in the Vienna VLBI Software (VieVS). We use the CONT11 data set with identical clocks at seven sites to validate the models in VieVS and to assess the impact of the combined solution on the geodetic products.