GPS stands for Global Positioning System, which is a satellite-based radio navigation system owned by the United States government and operated by the United States Space Force. It provides users with positioning, navigation, and timing (PNT) services anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. The system consists of three segments: the space segment, the control segment, and the user segment.
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Space Segment: The space segment consists of a nominal constellation of 24 operating satellites that transmit one-way signals that give the current GPS satellite position and time.
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Control Segment: The control segment consists of worldwide monitor and control stations that maintain the satellites in their proper orbits through occasional command maneuvers and adjust the satellite clocks. It tracks the GPS satellites, uploads updated navigational data, and maintains the health and status of the satellite constellation.
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User Segment: The user segment consists of the GPS receiver equipment, which receives the signals from the GPS satellites and uses them to calculate the users position, velocity, and time.
GPS was originally intended for military applications, but in the 1980s, the government made the system available for civilian use. GPS works in any weather conditions, anywhere in the world, 24 hours a day, and there are no subscription fees or setup charges to use GPS. The system provides critical capabilities to military, civil, and commercial users around the world.
