Network−Based Techniques for RTK Applications

Gerhard Wübbena，Andreas Bagge，Martin Schmitz
[ Link to geopp.com ]

Overview – The accuracy of today’s RTK is limited by the distance dependent errors from orbit, ionosphere and troposphere as well as station dependent influences like multipath and antenna phase center variations. The basic idea of Geo++® GNSMART (GNSS − State Monitoring And Representation Technique) is to analyze the data from a reference station network to estimate and represent the state of individual components of the GPS error budget in real−time.
All stations of a network are processed simultaneously for best estimation of global parameters and to increase the reliability of the results. The complete state can normally not be used by the rover directly. Therefore GNSMART can derive several types of representations from the complete state model, adequate for special transmission or rover requirements to reduce the GNSS error budget significantly. The implementation was operable before the current solar activity maximum, and is currently installed on many reference stations around the world under different ionospheric conditions. Recent results show the capabilities of GNSMART. Horizontal accuracy of 1 centimeter can be achieved with initialization times of 30 seconds, often even within 10 seconds over distances of more than 30 kilometer.
This study was issued on 14th-16th November 2001 in the GPS Symposium hosted by GPS Society, Japan Institute of Navigation.