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GNSS collectively refers to the worldwide positioning, navigation, and timing (PNT) determination capability available from one or more satellite constellations. Each GNSS system employs a constellation of satellites that operate in conjunction with a network of ground stations. Receivers and system integrity monitoring are augmented as necessary to support the required position, navigation, and timing performance for the intended operation.
NISTIR 8323r1 from USG FRP (2021) - adapted, ICAO 9849 - adapted