COoperative Network for GIOVE Observations (CONGO)
As a prototype for the satellites of the future European Global Navigation Satellite System Galileo, the European Space Agency (ESA) launched two satellites (GIOVE-A and GIOVE-B) as part of the Galileo in Orbit Validation Element (GIOVE). To gain experience with the signals transmitted by these satellites and to estimate satellite orbit and clock parameters, a global network of GIOVE-capable receivers was established. This Cooperative Network for GIOVE Observations (CONGO) is operated by Deutsches Zentrum für Luft- und Raumfahrt (DLR, Oberpfaffenhofen, Germany), Bundesamt für Kartographie und Geodäsie (BKG, Frankfurt, Germany), and Deutsches GeoForschungsZentrum (GFZ, Potsdam, Germany) in cooperation with several local station hosts. The data archiving as well as the orbit and clock determination are performed at IAPG.
Altogether 24 receivers are operated at 22 stations. One site is equipped with a Septentrio GeNeRx receiver, six sites with Leica GRX1200 receivers, and the other sites with Javad Triumph receivers. All stations provide dual-frequency observations of the GIOVE satellites in the E1 and E5a bands in addition to tracking of legacy L1 and L2 GPS signals. Individual stations furthermore support modernized GPS L2C and L5 signals, SBAS, GLONASS and QZSS (red squares) tracking or GIOVE E5b, E5 AltBOC, E6 tracking. All CONGO stations transmit their data in real-time via the Ntrip protocol.
Orbit and Clock Determination
The real-time streams are recorded, monitored, converted to RINEX 3.00 data, and archived at TUM. The RINEX data of the CONGO network is processed with a modified version of the Bernese GPS Software. In a first step, station coordinates, receiver clocks, and troposphere parameters are estimated in a GPS-only PPP solution. These parameters are kept fixed in the second step, the GIOVE orbit and clock estimation. Based on the orbit predictions, real-time clocks are computed by DLR.
Montenbruck, O.; Hauschild, A.; Hessels, U.; Steigenberger, P.; Hugentobler, U.: CONGO: First GPS/GIOVE tracking network for science, research; GPS World, Vol. 20, Nr. 9, pp 56-62, ISSN 1048-5104, 2009, External Link.
Cao, W.; Hauschild, A.; Steigenberger, P.; Langley, R. B.; Urquhart, L.; Santos, M.; Montenbruck, O.: Performance evaluation of integrated GPS/GIOVE precise point positioning; Proceedings of the 2010 International Technical Meeting (ITM) of the Institute of Navigation, pp 540-552, 2010, External Link, Download
Montenbruck, O.; Hauschild, A.; Erker, S.; Meurer, M.; Langley, R.; Steigenberger, P.: GPS L5, the real stuff; GPS World, Vol. 21, Nr. 7, pp 13-14, ISSN 1048-5104, 2010, Externer Link.
Montenbruck, O.; Hauschild, A.; Steigenberger, P.; Langley, R. B.: Three's the challenge: A close look at GPS SVN62 triple-frequency signal combinations finds carrier-phase variations on the new L5 ; GPS World, Vol. 21, Nr. 8, pp 8-19, ISSN 1048-5104, 2010, Externer Link.
Steigenberger, P.; Hugentobler, U.; Montenbruck, O.; Hauschild, A.: Precise orbit determination of GIOVE-B based on the CONGO network; Journal of Geodesy, Vol. 85, Nr. 6, pp 357-365, Springer, ISSN 0949-7714, DOI: 10.1007/s00190-011-0443-5, 2011, Externer Link.
A real-time orbit and clock product can be accessed from an FTP-server, where the latest SP3-file is provided with 5 min latency. Files are retained for one week. The FTP-Server can accessed as follows:
Local Station Hosts
- Geodätisches Observatorium Wettzell, Germany
- German Antarcitc Research Station (GARS) O'Higgins, Antarctica
- Hartebeesthoek Radio Astronomy Observatory, South Africa
- Japanese Space Exploration Agency, Japan
- Nanyang Technological University, Singapore
- Stanford University, USA
- Transportables Integriertes Geodätsiches Observatorium (TIGO), Chile
- University of Hawaii, USA
- University of New Brunswick, Canada
- University of New South Wales, Australia