The SLR data in the CDDIS are in the form of on-site normal point and full-rate data. In the early days of laser ranging data analysis, scientists typically required SLR full-rate data; these data included all valid points or returns from the satellite. Since 1988, SLR normal points have been produced from the global full-rate data set. Normal point data are compressed data using sampling over time based upon the presence of some minimum number of data points in the sampling interval. The monthly data volume is considerably reduced. Since the early 1990's, normal point are generated on-site by laser ranging systems and transmitted daily (and sometimes hourly) to a regional processing center via electronic means.
The data from each satellite are stored in separate files and directories, by satellite. Each file contains all data received during the last 24-hour period. Additionally, a single file containing all data received during the last 24 hours is available.
Data from the global laser ranging network are organized in subdirectories by
- File content (normal points, full-rate)
- List of SLR sites (see ILRS website for details: (http://ilrs.gsfc.nasa.gov/network/stations/index.html)
- Map of SLR sites
- Normal point data from 1991 through present
- Full-rate data from 1976 through present
- Coverage satellite dependent (see ILRS website for details: http://ilrs.gsfc.nasa.gov/missions/satellite_missions/index.html)
- Normal point data: ~1.25 Mbyte/day, 40 Mbyte/month
- Full-rate SLR data: ~10 Mbytes/day (compressed)
- Normal point data: Consolidated Laser Ranging Data (CRD) format, 2012 through present; ILRS Normal Point data format (formerly known as the CSTG format) prior to 2012
- Full-rate data: Consolidated Laser Ranging Data (CRD) format, 2012 through present; ILRS Full-Rate Data format (formerly known as the MERIT-II format, V2/V3) prior to 2012