EGNOS (European Geostationary Navigation Overlay Service) is essentially Europe’s ‘pre-GALILEO’ system, its first concrete venture into satellite navigation. EGNOS is to deliver services based on GPS and Glonass signals, providing augmentation signals re-transmitted by geostationary satellites and a network of ground stations.
EGNOS augments the two satellite navigation systems now operating, the US GPS and Russian GLONASS systems, and makes them suitable for safety critical applications such as flying aircraft or navigating ships through narrow channels.
EGNOS will increase the accuracy of existing satellite positioning services to below five metres, compared with about 20 meters with GPS and GLONASS. Moreover, it provides a crucial ‘integrity message’, informing users in the event of problems with the satellites. It will also transmit an extremely accurate universal time signal.