Service access

The EGNOS signal is broadcast by two Inmarsat-3 satellites – one positioned east of the Atlantic, and the other above Africa – and by ESA’s Artemis satellite, which is also above Africa. These three satellites’ orbits are in the equatorial plane, at three different longitudes, with each able to broadcast EGNOS services across Europe.

As with GPS satellites, each EGNOS satellite is allocated a unique PRN (Pseudo-Random Noise) number, which allows it to be identified by the user.

The NMEA standard, used in output mode by most commercially available receivers, allocates a unique identifier to each EGNOS satellite, as described in the table below.

Satellite PRN ID NMEA) Position

ARTEMIS

124

37

21.5E

INMARSAT AOR-E

120

33

15.5 W

INMARSAT IOR-W

126

39

25E

As a general rule, two satellites out of the three available are used operationally to broadcast the EGNOS message. The third is used for the purposes of maintenance, testing and validation (currently PRN126).

EGNOS Services

EGNOS offers all users of satellite radio navigation high-performance navigation and positioning services, superior to that currently available in Europe. The three services available are:

  • Open Service
  • Safety-of-Life Service
  • EGNOS Data Access Server (EDAS)

For the EGNOS Open Service, the signal-in-space has been continuously available since October 2009. EGNOS Open Service provides unprecedented positioning precision by improving the accuracy of GPS. EGNOS has demonstrated excellent signal quality throughout Europe.

The continuing monitoring of the augmentation signal shows it improves the accuracy of GPS to within one to two meters and is available more than 99 percent of the time. By comparison, someone using a GPS receiver that is not EGNOS enabled can only be sure of their position to within 17 metres.

A second key milestone will be achieved in 2010, when ESSP will be certified in compliance with the Single European Sky regulations. The Safety-Of-Life Service will be declared operationally ready.

EGNOS also provides a terrestrial commercial data service: EDAS (EGNOS Data Access Service).

EDAS disseminates EGNOS data in real-time and is the single point of access for the data collected and generated by the EGNOS infrastructure. EDAS allows users to "plug in" to EGNOS by providing access to satellite navigation data generated by ground stations distributed over Europe and North Africa.

EDAS

EGNOS provides a terrestrial commercial data service called the EGNOS Data Access Service (EDAS).

EDAS is the single point of access for the data collected and generated by the EGNOS infrastructure. It supports the multimodal use of EGNOS (and later on Galileo) by disseminating EGNOS’ services in real time.

In order to understand the market’s interest for EDAS data, the GSA has designed a beta test to allow industry, research institutes, and private and public organisations to free access to EDAS’ data. This test provides information to the provider of the EDAS service about potential users and how they use the data.

Access to the EDAS data is possible by one of the two following means:

  • Internet connection, which allows the full transmission of all data without a latency and data integrity guarantee.
  • Higher performance point-to-point (PTP) direct link to the EDAS server. In this case every user would pay for the full cost of the link.

The standard and easiest way to receive EDAS is over the internet. Simply by downloading the client software, users can receive EDAS through a typical broadband internet connection.

For more information on EDAS and how to access the service go to the EDAS website.