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12.42 GNSS Instruments
12.42.2 Describe the basic principles and operation of a GNSS (Global Navigation Satellite System).
The Global Navigation Satellite System (GNSS) is a satellite-based navigation system that provides location and time information anywhere on or near the Earth's surface. The system consists of a network of satellites, ground control stations, and user receivers. GNSS satellites transmit signals that are received by GNSS receivers on the ground. The receiver uses the signals to determine its location, velocity, and time. The receiver calculates its position by measuring the time it takes for the signals to travel from the satellites to the receiver. The receiver uses the signals from multiple satellites to determine its position with high accuracy. There are several GNSS systems in operation, including the United States' GPS, Russia's GLONASS, China's BeiDou, and the European Union's Galileo. These systems use slightly different technology but operate on the same basic principles. GNSS has many applications, including navigation for aircraft, ships, and ground vehicles, surveying, mapping, and location-based services. The system is also used for scientific research, including monitoring the movement of tectonic plates and studying the Earth's atmosphere.