The CHAMP satellite and its on-board instruments continuously produced science data with an overall rate of 10.8kbit/s, and the satellite added 2.2kbit/s of spacecraft house-keeping data, in total 141MByte/d, which could to be downloaded to the 7.3m ground antenna of DLR's receiving station in Neustrelitz (53.5°N, 13°E).
With its telemetry bitrate of 1000kbit/s and a contact time of 28min/d at 450km and 20min/d at 300km S/C altitude during the three to five passes per day, Neustrelitz was capable to receive 210MByte/d (at 450km) and 150MByte/d (at 300km), respectively, of dump data. A second ground station ground station in Weilheim (48°N, 11°E), belonging to DLR's Mission Control Center, was operating as the commanding and satellite control station. It received 'real-time' science and H/K data at a bitrate of 32kbit/s and sent commands at 4kbit/s. Weilheim also served as a back-up station to Neustrelitz, then was being capable to switch to a 1000kbit/s down-link telemetry bitrate.
CHAMP's on-board mass memory unit was organized as a ring buffer and consisted of a science data segment of 100MByte and a H/K data segment of 25Mbyte storage capacity. The on-board data were written and dumped sequentially controlled by a write and dump pointer. The maximum buffer time (maximum time between two overflights over Neustrelitz) was 13 hours. If, by failure, the buffer run full, then the oldest data would have been overwritten.
CHAMP's Raw Data Centre was established at the receiving station Neustrelitz with the following functions: telemetry data reception (Transfer Frames) and long-term storage in the Raw Data Archive, demultiplexing and extraction of science and H/K application packets (level-0 data), immediate transfer of H/K packets to DLR/GSOC, and temporary storage of all level-0 data in the level-0 rolling archive for access by the instrument manufacturers and the processing centre at GFZ Potsdam, where the level-0 long-term archive is located.
The products of levels 1 through 4 were generated at the Science Data System GFZ Potsdam within the
and at DLR-DFD Neustrelitz within the
Product archiving, administration and retrieval were organized by the CHAMP Information System and Data Centre (ISDC), located at GFZ Potsdam, which also was the users' www- and ftp-based interface for access to all scientific products of levels 1 through 4.
CHAMP's standard science products were labeled from level-0 to level-4 according to the number of processing steps applied to the original data. Decommutation and Decoding of level-0 data resulted in level-1 products. These were dump-related files, associated with each individual instrument and source aboard CHAMP, and the data content was transformed from the telemetry format and units into an application software readable format and physical units. Level-1 products also include the ground station GPS and laser data. Level-2 products are preprocessed, edited and calibrated experiment data supplemented with necessary spacecraft housekeeping data and arranged in daily files. Level-3 products comprise the operational rapid products and fine processed, edited and definitely calibrated experiment data. Finally, level-4 leads to the geoscientific models derived from the analysis of CHAMP experiment data, supported and value-added by external models and observations.
Within the three fields of research and application persued with CHAMP, the following higher level products were generated: