CNES projects library

April 5, 2018


The EGNOS service corrects and augments GPS signals and certifies their integrity. The project is built around a network of ground stations and several geostationary satellite payloads covering the European Union.

Developed between 1995 and 2009, EGNOS (European Geostationary Navigation Overlay Service) was Europe’s first satellite navigation project. The service has delivered very good performance since its deployment and uptake by users is rising regularly. EGNOS receives and measures signals from the GPS constellation in Europe, compares them with the position of its stations, calculates positional and integrity errors and feeds them into a centralized system to provide ‘certified’ information. EGNOS payloads on several geostationary satellites then relay this information for processing by positioning satellites with location information.

While EGNOS augments precision, above all it delivers reliable positional information in real time. The service was designed for air navigation and serves other critical applications like rail, but it is also aiding agriculture and robotics, for example. EGNOS units—the first of which were developed in partnership with CNES—are flying on geostationary satellites as a result of partnership agreements secured in 1996, 2001, 2005, 2012 and 2014. But the system relies especially on an infrastructure of 40 Ranging and Integrity Monitoring Stations (RIMS) on the ground that receive and measure GPS signals, six Navigation Land Earth Stations (NLES) that serve as ‘reference points’ and two control centres handling EGNOS communications and operations.

EGNOS offers two services:

  • A Safety of Life (SoL) signal that exploits all the power of EGNOS to deliver optimum reliability. Recognized by civil aviation bodies, the SoL signal is increasingly used by airports for procedures on the ground and in flight, and for precise aircraft guidance.
  • EDAS (EGNOS Data Access Service), an open service providing access to raw positional data and corrections from satellites in real time.

EGNOS is today a vital tool for the air transport sector.

Long-term upgrades to this European service are planned, notably for 2025 to support multi-constellation and multi-frequency signals like those from Galileo.

Download the form to obtain the EGNOS guide (in french)