L. Petrov
Steps towards phase delay VLBI
 
                   ABSTRACT
 
 
One of the promising ways for improving precision of estimation of
the targeted parameters of geodetic VLBI is to use phase delay measurements
which are roughly 40-fold more precise than group delay observables. However
phase delay ambiguities should be resolved before using these observables
in LSQ adjustments. This problem is solved almost always for the case of
relatively short baselines (1-10 km) where we are able to ignore an
atmosphere contribution to time delay, but it is still a challenge for the
case of longer baselines.
procedure for resolving phase delay ambiguity is presented. It exploits
the fact that phase misclosures are usually a small fraction of phase
ambiguity spacings. Phase delay measurements made in the network consisting
of three or more stations provide some redundancy.
It is shown that the proposed approach allows to resolve phase delay
ambiguities for a subset of observations. Some results of phase delay
solutions of EUROPE, IRIS-S and VLBA networks are presented. It was found
that the success rate of phase delay ambiguity resolution for intercontinental
baselines depends on the system sensitivity, the level of instrumental noise
and the number of observations. Phase delay ambiguities can be resolved for up
to 90% observations for the best, state-of-art VLBI experiments, although
a success rate 40-70% is more typical.
 
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In Proceedings of the 13th Working Meeting on European VLBI for Geodesy
and Astrometry, Viechtach, 1999
 
Keywords: phase delay, precision, accuracy