Co-location of space geodetics techniques in Space and on the ground

Other conference contribution, 2013

The most demanding goal of the Global Geodetic Observing System (GGOS) initiative is the definition of station positions to an accuracy of 1 mm and the corresponding velocities to 0.1 mm/year. Fundamental stations are core sites in this respect, because they collocate the geodetic relevant space techniques. However this requires unprecedented control over local ties, intra- and inter-technique biases. To improve the accuracy of the geodetic techniques, new concepts for the monitoring and controlling of local ties and biases have to be implemented.We are developing a symmetric two-way measurement technique to identify unaccounted system delays within and between the instrumentation of the Geodetic Observatory Wettzell. It requires redesign of the VLBI (Very Long Baseline Interferometry) phase calibration generator to be compatible with such an two-way measurement technique and VLBI2010. Another activity is the mapping of Global Navigation Satellite System (GNSS) satellites into the frame of the quasars using VLBI telescope, in geodetic mode. This corresponds to a collocation of geodetic techniques in space. The receiver of the 20 m radio telescope Wettzell (RTW) has been modified to measure the GNSS L1 signal without changing the physical reference point. Preliminary experiments have already been executed.