What is GNSS?

Global Navigation Satellite System (GNSS) is the infrastructure that allows users with a compatible device to determine their position, velocity and local time by processing signals from satellites in space. GNSS signals are provided by a variety of satellite positioning systems, including global constellations and Satellite-Based Augmentation Systems. n Global constellations: l GPS: The first GNSS, fully operational since 1995, is managed by the US Department of Defence. l GLONASS: The Russian GNSS, completed in 1995 and fully operational since 2011, is managed by the Russian Aerospace Defence Forces. l Galileo: Europe’s GNSS, currently under development as the only civil GNSS, is owned and managed by the European Union. l BeiDou (COMPASS): The Chinese GNSS, set to supersede the COMPASS regional system operating since 2000, is managed by the governmental China Satellite Navigation Office. n Satellite-Based Augmentation Systems (SBAS), such as EGNOS (Europe), WAAS (North America), GAGAN (India) and MSAS (Japan). What aspects of GNSS are important? GNSS is used for many types of applications, covering the mass market, professional and safety-crit- ical applications – each requiring different service levels (Open Service, Safety of Life, Search and Rescue). Depending on user needs, important features of GNSS include: n Availability: Percentage of time the minimum number of satellites are in view, so the position, navigation or timing solution can be computed by the user. n Accuracy: difference between true and computed position (absolute positioning). n Continuity: Ability to provide the required performances during an operation without inter- ruption, once the operation has started. n Integrity: Additional user information on the reliability of the signal within the operational requirements. n Robustness to spoofing and jamming: Authentication information provided to users ensuring the signal comes from a satellite in space (enabling sensitive applications). n Indoor penetration: Ability of signal to penetrate inside buildings, e.g. through windows.