Global Positioning System (GPS) is defined as the constellation of satellites and was designed as a dual-use system with the primary purpose of enhancing the effectiveness of U.S. and allied military forces.
GPS is rapidly becoming an integral component of the emerging Global Information Infrastructure, with applications ranging from mapping and surveying to international air traffic management and global change research.
Developed by the United States Department of Defense, it is officially named NAVSTAR GPS (Contrary to popular belief, NAVSTAR is not an acronym, but simply a name given by Mr. John Walsh, a key decision maker when it came to the budget for the GPS program). The satellite constellation is managed by the United States Air Force 50th Space Wing.
The cost of maintaining the system is approximately US$750 million per year, including the replacement of aging satellites, and research and development. Despite these costs, GPS is free for civilian use as a public good.GPS has become a widely used aid to navigation worldwide, and a useful tool for map-making, land surveying, commerce, and scientific uses.
GPS also provides a precise time reference used in many applications including scientific study of earthquakes, and synchronization of telecommunications networks.
method of operation.
A GPS receiver calculates its position by measuring the distance between itself and three or more GPS satellites. Measuring the time delay between transmission and reception of each GPS microwave signal gives the distance to each satellite, since the signal travels at a known speed near the speed of light.