Global Navigation Satellite Systems (GNSS) form a key technology in the communications, navigation, and surveillance (CNS) infrastructure. GNSS can support navigation applications in all phases of flight as well as surveillance applications such as ADS-B. It ensures:
- accuracy in terms of position, speed or time;
- integrity, by providing confidence in GNSS performance and providing an alert if confidence dips below a certain level;
- continuity of service - it is able to function without interruption;
- availability: the percentage of time a signal takes to meet the stated accuracy, integrity and continuity criteria.