Co-location of space geodetics techniques in Space and on the ground
Konferensbidrag (offentliggjort, men ej förlagsutgivet), 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.
GNSS with VLBI
Two-way Measurement
L-band receiver