On 31 October 2020, anonymous ftp access will officially be discontinued at CDDIS. Beginning August 10, 2020, CDDIS will bandwidth limit ALL IPs using anonymous ftp to just 250KB/s transfer rates. CDDIS is STRONGLY recommending all users begin to transition to using alternate method of access to the CDDIS archive. Examples of alternate methods can be found at: https://cddis.nasa.gov/Data_and_Derived_Products/CDDIS_Archive_Access.html.

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Hourly 30-second data

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 one hour of data. IGS analysis centers retrieve these hourly data files to produce IGS "rapid" and "ultra-rapid" products such as satellite ephemerides, clocks, and Earth rotation parameters, which are then submitted to the CDDIS. The IGS Analysis Center Coordinator generates a daily, combined, rapid product with a 17-hour latency. The ultra-rapid (predicted) orbit and clock products are generated four times per day.

IGS stations forward hourly 30-second GNSS data in compressed RINEX format to the CDDIS within minutes following the end of the hour. At the present time, an average of 350 sites are archived in this fashion each day for availability to the global science community. Hourly GNSS data available in RINEX V2 format use the mmmmDDDH.YYt.Z filename convention and are in UNIX compressed format. Starting with data from 2016, all hourly GNSS data in RINEX V3 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/hourly area.

At the close of the UTC data, the station operators incorporate individual hourly GNSS data into a full day's data file, submitted to the CDDIS and made available in the daily GNSS data directories. These hourly files are stored in hourly subdirectories within the file system.

The starting directory for these files is:


Append the following directory and file names tot he starting directory using the format codes in the links below: