The CDDIS archive contains GNSS data from the global network of permanent GNSS receivers supporting the IGS operating at a 30-second sampling rate and containing 24 hours of data (00:00-23:59 UTC). IGS analysis centers retrieve these data daily to produce IGS products. These products, such as the daily and weekly satellite ephemerides, station positions and velocities, satellite and station clock information, and the Earth rotation parameters, are in turn, submitted to the CDDIS.
IGS regional data collection centers forward their data holdings of these daily, 30-second GNSS data in compressed RINEX format to the CDDIS on a daily basis. At the present time, an average of nearly 500 sites are archived in this fashion each day for availability to the global science community. In general, a majority of the data delivered to and archived in the CDDIS are available to the user community within a few minutes (to a few hours) after the end of the observation day.
Daily GNSS data available in RINEX V2 format use the mmmmDDD#.YYt.Z filename convention and are in UNIX compressed format. Starting with data from 2016, all daily GNSS data in RINEX V3 format that use the RINEX V3 filenaming convention and the gzip compression format are archived with data in RINEX V2 format, in subdirectories in the /gnss/data/daily area.
For RINEX V2 data, the CDDIS utilizes UNAVCO's TEQC (Translation, Editing and Quality Checking) software on incoming daily 30-second files for quality checking purposes. Metadata are extracted from the TEQC output and stored in the CDDIS database. Data quality information is also maintained in daily "status" files that reflect the timeliness of the data delivered as well as statistics on number of data points, cycle slips, and multipath. Users can thus obtain a snapshot of data availability and quality by viewing the contents of these summary files. Valid data are then archived on-line in daily subdirectories by year, day, and file type within the file system.
The CDDIS provides a report that summarizes the contents of a day’s GNSS data holdings. These "status files" reflect timeliness of the data delivered as well as statistics, extracted from the TEQC summaries, on number of data points, cycle slips, and multipath. The user can receive a snapshot of data availability and quality by viewing the contents of such a summary file.
RINEX V2 and RINEX V3 files are archived in the same directories.
The starting directory for the files is:
Append the following directory names to the starting directory to access individual files:
|DDD||3-digit day of year|
|t||type of data:
d = Hatanaka-compressed observation data
f = Compass/Beidou broadcast ephemeris
g = GLONASS broadcast ephemeris data
h = SBAS broadcast ephemeris
l = Galileo broadcast ephemeris
m = meteorological data
n = GPS broadcast ephemeris data
o = observation data
p = Combined broadcast ephemeris
q = QZSS broadcast ephemeris
s = observation summary files (output of TEQC)
Append the following file names using the format codes below:
mmmmDDD#.YYt.ZRINEX V2 format View code table
XXXXMRCCC_K_YYYYDDDHHMM_01D_30S_tt.FFF.gzRINEX V3 format View code table