The first pillar of Europe’s navigation programme, EGNOS, is alread operational, sharpening the accuracy of GPS signals across Europe. In addition, it informs users about the current integrity (level of reliability) of the system based on the GPS satellites’ orbits, atomic clock accuracy and ionospheric delay. If the accuracy of the signal falls below a given threshold, users are warned within six seconds.
The Open Service, for applications where human life is not at stake, such as personal navigation, goods tracking and precision farming, has been available since October 2009.
The Safety-of-Life Service, where human lives depend on the accuracy and integrity of the signals, became available for its primary purpose of aircraft navigation (beginning with vertical guidance for landing approaches) in March 2011.
The system is based on a network of ground stations, control centres and three geostationary satellites. The ground stations gather data on the current accuracy of GPS signals and embed it in the EGNOS signal, which is uplinked to the satellites to be transmitted to users.
EGNOS is designed against international standards set by the International Civil Aviation Organisation (ICAO) and its development was coordinated with other satellite-based augmentation systems around the world: MSAS in Japan, WAAS in the US, and GAGAN in India.
Tomorrow: EGNOS plus Galileo
Once Galileo becomes operational, a portfolio of navigation services will be offered by Galileo and EGNOS, based on varying user needs:
• Open Service The Galileo navigational signal will be accessible by the general public free of charge, providing improved global positioning.
• Public Regulated Service Two encrypted signals with controlled access for specific users such as governmental bodies.
• Search and Rescue Service Galileo will contribute to the international Cospas–Sarsat international system for search and rescue. A distress signal will be relayed to the Rescue Coordination Centre and Galileo will inform the user that their situation has been detected.
• Safety-of-Life Service Already available for aviation to the ICAO standard thanks to EGNOS, Galileo will further improve the service performance.
• Commercial Service Galileo will provide a signal for high data throughput and highly accurate authenticated data, particularly interesting for professional users. The potential applications of satellite navigation are virtually limitless. Beyond the safety, efficiency and comfort that satnav brings to the transport sector, it will become a valuable tool for nearly all economic sectors. Keeping track of where you are will be as important as knowing the time of day. Integration of satnav services with other technologies such as mobile communications or traditional navigation aids will multiply their usefulness.