EGNOS System

EGNOS is comprised of four functional segments:

Ground segment

A network of 40 Ranging Integrity Monitoring Stations (RIMS), 2 Mission Control Centres (MCC), 2 Navigation Land Earth Stations (NLES) per GEO, and the EGNOS Wide Area Network (EWAN), which provides the communication network for all the components of the ground segment.

  • 40 RIMS: the main function of the RIMS is to collect measurements from GPS satellites and transmit these raw data each second to the MCCs. The configuration used for the initial EGNOS OS includes 40 RIMS sites located over a wide geographical area.
  • 2 MCC: they receive the information from the RIMS and generate correction and satellite status messages to provide user integrity and enhance user accuracy. The MCC acts as the EGNOS system’s 'brain'. 
  • 2 NLESs per GEO: the NLESs transmit the EGNOS messages generated by the MCCs to the GEO satellites to be broadcast to the EGNOS users and to ensure the synchronisation with the GPS signal.

Space Segment

Composed of at least three GEO satellites broadcasting corrections and integrity information for GPS satellites in the L1 frequency band (1575,42 MHz). This space segment configuration provides a high level of redundancy over the whole service area in case of a geostationary satellite link failure. EGNOS operations are handled in such a way that, at any point in time, at least two of the three GEOs broadcast an operational signal.

Support segment

In addition to the stations/centres, the system has other ground support installations that perform the activities of system operations planning and performance assessment, namely the Performance Assessment and Checkout Facility (PACF) and the Application Specific Qualification Facility (ASQF) which are operated by the EGNOS Service Provider (ESSP).

  • PACF: provides support to EGNOS management in such area as performance analysis, troubleshooting and operational procedures, as well as upgrade of specification and validation, and support to maintenance.
  • ASQF: provides civil aviation and aeronautical certification authorities with the tools to qualify, validate and certify the different EGNOS applications.

User Segment

The EGNOS User segment is comprised of EGNOS receivers that enable their users to accurately compute their positions with integrity. To receive EGNOS signals, the end user must use an EGNOS-compatible receiver. Currently, EGNOS compatible receivers are available for such market segments as agriculture, aviation, maritime, rail, mapping/surveying, road an location based services (LBS).

For further information, visit the EGNOS User Support portal.

EGNOS ground segment

EGNOS ground segment, with locations of  Support Facilities, MCCs, RIMSs and NLES.

Updated: Apr 12, 2023