DGPS uses a network of fixed, ground-based reference stations to broadcast the difference between the positions indicated by the satellite systems and the known fixed positions. These stations broadcast the difference between the measured satellite pseudoranges and actual (internally computed) pseudoranges, and receiver stations may correct their pseudoranges by the same amount. The digital correction signal is typically broadcast locally over ground-based transmitters of shorter range.
GNSS Augmentation of a global navigation satellite system (GNSS) is a method of improving the navigation system’s attributes, such as accuracy, reliability, and availability, through the integration of external information into the calculation process. Ground based augmentation systems are commonly composed of one or more accurately surveyed ground stations, which take measurements concerning the GNSS, and one or more radio transmitters, which transmit the information directly to the end user.
Generally, GBAS networks are considered localized, supporting receivers within 20 kilometres, and transmitting in the very high frequency (VHF) or ultra high frequency (UHF) bands.
To ensure such a range, customers working in the field of Land Survey, Marine Survey as well as Machine Control rely on Satel to achieve such distance.