High-Rate/Low-Latency (HR/LL) GPS Global Ground Tracking Network

R. Galas, Ch. Reigber, M. Ramatschi

The High-Rate/Low-Latency (HR/LL) GPS ground tracking network is established jointly by GFZ and JPL to ensure adequate ground data availability for CHAMP and GRACE satellite missions. Below only the GFZ network is presented.

Station: Lon: Lat: Owner/Type: Comment:

Click on the station location in the map above or click on the following log filenames to view the station log file: potm0107.log ban20107.log obem0107.log wuh20104.log sutm0107.log ous20105.log nya20107.log lpgm0105.log mizu0107.log jogj0110.log kstu0102.log ulab0107.log zwen0009.log tash0201.log riog_20020628.log hlfx_20030305.log

The network meets the following requirements:

• Tracking stations are self-controlled and remotely maintained.
• On site computers have ring-data-archive of size of at least two weeks.
• Sampling rate of GPS data is 1 sec.
• The data files are delivered in "near-real-time mode" to the GFZ (in portions covering 15 min. time span).
• Station status files are transmitted as well.
• Latency of observation files does not exceed 20-30 min.

Each of the station is composed of:

• An "off the shell" precise, dual frequency, geodetic GPS receiver.
• A meteorological station.
• An industry standard computer (running under Linux OS).
• A power controller with relays and a watch-dog.
• A battery with a charger.
• Dedicated (permanent) Internet access.

Field tracking station (version with redundant components)

14 stations are equipped with the "BenchMark ACT" receivers from AOA and one Ashtech Z-12 receiver is installed at Rio Grande. The GPS data is logged and accumulated on site onto 15-min files in the receiver binary format. Some Auxiliary data (e.g. meteorological, station-status) are transmitted as hourly files. Recently he station are being equipped with external frequency standards (rubidium or cesium) and some of them are upgraded to disseminate GOP data in real-time (real-time data streaming).