The two core satellite constellations are the Global Positioning System (GPS) of the US and the Global Navigation Satellite System (GLONASS) of Russia/India. The third constellation will be the European Union Galileo system when it becomes fully operational. These systems provide independent capabilities and can be used in combination with future core constellations and augmentation systems. Signals from core satellite are received by ground reference stations and any errors in the signals are identified. Each station in the network relays the data to area-wide master stations where correction information for specific geographical areas is computed. The correction message is prepared and uplinked to a geostationary communication satellite (GEO) via a ground uplink station. This message is broadcast to receivers on board aircraft flying within the broadcast coverage area of the system. The system is known in the US as WAAS (Wide Area Augmentation System), in Europe as EGNOS (European Geostationary Navigation Overlay System), in Japan as MSAS (MTSAT Satellite Based Augmentation System) and in India as GAGAN (GPS-aided geo-augmented navigation).
The two core satellite constellations are the Global Position,ing System (GPS) of the US and the Global Navigation Satellite System (GLONASS) of Russia/India. The third constellation will be the European Union Galileo system when it becomes fully operational. These systems provide independent capabilities and can be used in combination with future core constellations and augmentation systems. Signals from core satellite are received by ground referen?ce stations and any errors in the signals are identified. Each station in the network relays the data to area-wide master stations where correction information for specific geographical areas ?is computed. The correction message is pr!epared and uplinked to a geostationary communication satellite (GEO) via a ground uplink station. This messa,ge is broadcast to receivers on board aircraft flying within the broadcast coverage area of the system. The system is known in the US as WAAS (Wide Area Augmentation System), in Europe as EGNOS (European Geostationary Navigation Overlay System), in Japan as MSAS (MTSAT Satellite Based Augmentation System) and in India as GAGAN (GPS-aided geo-augmented navigation).