GPS, an acronym for Global Positioning System, refers to a worldwide satellite-based radionavigation system. This infrastructure comprises a constellation of twenty-four satellites orbiting the Earth, maintained and supported by the U.S. Department of Defense. While its inception and primary design were intended for military objectives, its availability was extended to civilian applications after the year nineteen-eighty. The system operates continuously—twenty-four hours a day—under all weather conditions across the globe, providing services to users free of charge. These satellites complete two precise orbits around the Earth daily, transmitting coded signals containing vital data to terrestrial receivers.
The operational principle of GPS relies on calculating the time difference between the transmission and reception of a signal from a satellite. This duration determines the exact distance of the receiver from the satellite. By measuring distances from multiple satellites, the system can pinpoint the user’s location and display it on electronic maps. A GPS receiver requires signals from at least three satellites to determine a two-dimensional position (latitude and longitude), whereas a minimum of four satellites is essential for a three-dimensional fix, which includes altitude above sea level. Furthermore, GPS technology is extensively utilized for velocity measurement, navigation, search operations, long-distance tracking, route sketching, and calculating sunrise and sunset times.