Go to top of page
Broadcast ephemeris data

A large percentage of the GNSS sites provide broadcast navigation data in addition to observation data. The CDDIS creates daily broadcast ephemeris files from these site-specific files transmitted by the stations; these files (one for GPS, a second for GLONASS) contain the unique GPS or GLONASS satellite ephemeris messages for each day. A similar file is created at the start of the UTC day and updated on an hourly basis from the hourly broadcast navigation files. Users can therefore download a single file each day or hour, which contains all broadcast ephemeris messages required for post-processing.

Daily GPS Broadcast Ephemeris Files

The daily GPS broadcast ephemeris file is a merge of the individual site navigation files into one, non-redundant file that can be utilized by users instead of the many individual navigation files.

The daily file created at BKG each day contains unique navigation messages from sites in Europe.

The starting directory for the daily files is

ftp://cddis.gsfc.nasa.gov/gnss/data/daily/.

Append the following directory and file names to the starting directory:

YYYY/DDD/YYn/brdcDDD0.YYn.Z   (merged GPS broadcast ephemeris file)

OR

YYYY/brdc/brdcDDD0.YYn.Z   (merged GPS broadcast ephemeris file)

YYYY/DDD/YYn/ifagDDD0.YYn.Z   (daily file historically created at BKG)

as described in the table at the bottom of the page.

Hourly GPS Broadcast Ephemeris Files

The combined broadcast ephemeris file is generated on an hourly basis from all hourly navigation files archived at the CDDIS. The hourly navigation file contains all broadcast messages with the TOE of the day that are available when the file is created at the top of the hour. The file is updated each hour with new navigation messages.

At the end of the UTC day, when the final version of the file is generated, the file is copied to the daily directories and becomes the "daily" broadcast ephemeris file

The starting directory for the hourly files is

ftp://cddis.gsfc.nasa.gov/gnss/data/hourly/

Append the following directory and file names to the starting directory:

YYYY/DDD/hourDDDm.YYn.Z

as described in the table at the bottom of the page.

Daily GLONASS Broadcast Ephemeris Files

Similarly, the daily GLONASS-only broadcast ephemeris file can be found in the GLONASS navigation file subdirectory.

The starting directory for thedaily GLONASS-only files is

ftp://cddis.gsfc.nasa.gov/gnss/data/daily/.

Append the following directory and file names to the starting directory:

YYYY/DDD/YYg/brdcDDD0.YYg.Z

OR

YYYY/brdc/brdcDDD0.YYg.Z

The following codes are used in the paths and file names for the data:

Code Meaning
YYYY4-digit year
YY2-digit year
DDD 3-digit day of year
.Z compressed Unix file