(
European
Geostationary
Navigation
Overlay
Service) A European system of earth stations and satellites that improves the tracking accuracy of the GPS and GLONASS navigation systems down to approximately 15 feet. Launched in 2004, EGNOS comprises 34 reference stations and three satellites that cover most of Europe. The stations track the navigation satellites and send correction signals to the EGNOS satellites, which transmit them to EGNOS-enabled receivers. See
GPS augmentation system and
Galileo.