The combination of normal equations or solutions from different VLBI analysis centers (so-called intra-technique combination) is a valuable method for mutual quality control. Furthermore, it is a prerequisite for the determination of highly accurate terrestrial reference frames (such as the DTRF) where intra-technique combinations of the techniques VLBI, SLR, GNSS and DORIS are combined (inter-technique combination). The primary research activities at DGFI-TUM in this context are the development and implementation of advanced approaches for intra-technique combination and investigations on the most appropriate stochastic modeling.
Jointly with the Bundesamt für Kartographie und Geodäsie (BKG), DGFI-TUM operates the IVS Combination Center that has been established by the International VLBI Service for Geodesy and Astrometry (IVS) in the year 2008. In this context, DGFI-TUM is in particular responsible for the further enhancement of the combination software DOGS-CS according to the newest scientific results and developments.