To overcome this situation, the Deutsches Zentrum für Luftund Raumfahrt (DLR, Oberpfaffenhofen, Germany) initiated the installation of the COperative Network for Giove Observations (CONGO) two years ago. In a joint effort with Bundesamt für Kartographie und Geodäsie (BKG, Frankfurt, Germany) it grew to a global network with currently 10 stations. Whereas the GESS network operates the same receiver and antenna type at all sites, the CONGO stations include equipment from different manufacturers. This heterogeneous configuration more closely resembles a future GNSS network for scientific applications where hardware biases will play an important role.