EGNOS – the first pan-European satellite navigation system
The European Geostationary Navigation Overlay Service (EGNOS) is the first pan-European satellite navigation system. It augments the US GPS satellite navigation system and makes it suitable for safety-critical applications such as flying aircraft or navigating ships through narrow channels.
Consisting of three geostationary satellites and a network of ground stations, EGNOS achieves its aim by transmitting a signal containing information on the reliability and accuracy of the positioning signals sent out by GPS. It allows users in Europe and beyond to determine their position within 1.5 metres.
Known as a satellite-based augmentation system (SBAS), EGNOS provides both correction and integrity information about the GPS system, delivering opportunities for Europeans to use the more accurate positioning data for improving existing services or developing a wide range of new services.
As a satellite navigation augmentation system, EGNOS improves the accuracy of GPS by providing a positioning accuracy to within three metres. By comparison, someone using a GPS receiver without EGNOS can only be sure of their position to within 17 metres.
EGNOS also provides verification of the system’s integrity, which relates to the trust that can be placed in the correctness of the location information supplied by the navigation system. In addition, it provides timely warnings when the system or its data should not be used for navigation. Integrity is a feature which meets the demands of safety-critical applications in sectors such as aviation and maritime, where lives might be endangered if the location signals are incorrect.
EGNOS’ infrastructure consists of three geostationary satellites over Europe and a network of ground stations. Since it is based on GPS, the EGNOS signal does not require major changes to receivers. Today, many GPS receivers available on the market are also EGNOS enabled.
The development of EGNOS arose from a tripartite agreement between the European Space Agency (ESA), the European Commission (EC) and Eurocontrol, the European Organisation for the Safety of Air Navigation. It is the precursor to Galileo, the global navigation satellite system (GNSS) being developed by the European Union. EGNOS and Galileo are now part of Europe’s GNSS programmes managed by the European Commission.
EGNOS will offer three services. These are:
- Open Service: The service is provided free of charge without any guarantee or resulting liability. It is open for use to anyone with an EGNOS-enabled satellite navigation receiver. This can be any receiver compatible with satellite-based augmentation systems. The Open Service was launched on 1 October 2009.
- Safety-of-life Service: EGNOS provides a valuable integrity message warning the user of any malfunction of the GPS signal within six seconds. This integrity message is essential when satellite navigation is used for applications where lives are at stake. The EGNOS Safety-of-life Service was certified for civil aviation in 2011.
- Commercial Service: EGNOS provides a terrestrial commercial data service called the EGNOS Data Access Service (EDAS). EDAS disseminates EGNOS data in real time and is the single point of access for the data collected and generated by the EGNOS infrastructure.