NASA Home Page JPL Home Page Caltech Home Page
NASA - Jet Propulstion Laboratory vertical separator + View the NASA Portal
JPL Home JPL - Earth JPL - Solar System JPL - Stars and Galaxies JPL - Technology
Global Differential GPS System
Home
About Us
System Description
- Overview
- Network
- Software
- References
Applications
Live Performance Monitoring
Customer Portal
Broadcast Ephemeris & Almanac

We distill the GPS broadcast ephemerides and almanacs from the navigation message received by our vast ground network, weeding out bit errors and data errors with strong majority voting schemes.

Both the broadcast ephemerides and the broadcast almanacs for each GPS satellite are available in a RINEX-like file format. We include the "Klobuchar" ionosphere correction parameters in the broadcast ephemeris files. The full resolution broadcast ephemerides are also available in a streaming socket format.

The almanac is also available in Yuma file format.

Additional broadcast parameters needed for some A-GPS protocols, but that are not part of the RINEX standard, are provided in a separate 'delta' file. We also embed in these 'delta' files real-time URE performance metrics from the GDGPS orbit determination process, for actual, up to the minute satellite performance status.

The RINEX broadcast ephemeris files are updated every 5 minutes. The ephemeris 'delta' files are updated every minute. The almanac files, in both the RINEX-like format and Yuma format are updated every 12.5 minutes. The broadcast ephemeris (with the parameters of the RINEX file) is also available as a continuous UDP data stream.

Access to all these products is available concurrently from multiple redundant data centers for optimal reliability.

Real-time GNSS
Products & Services
Precise, Global, Reliable
- Embedded Autonomous Ephemeris Prediction (AEP) software
- Orbit & Clock Corrections
- Orbit & Clock States
- Broadcast Ephemeris & Almanac
- Complete 50 bps Navigation Message
- Global Ionospheric (TEC) Maps
- Raw Measurements
- Predicted Orbit & Clock States
- Integrity & Performance Monitoring
- Global Virtual Reference Network
- Assisted GPS Data
- Assisted GLONASS Data
- GLONASS corrections, orbit and clocks

- Automatic Precise Positioning Service
- GREAT ALERT
- Consulting
link to First Gov NASA logo