Glossary definition of Global Positioning System

Also known as: GPS

Global Positioning System (GPS) is a worldwide location and navigation system based on a set of satellites orbiting the Earth, which can be used to determine terrestrial position, velocity, and time. The GPS system is owned and operated by the U.S. Department of Defense, but is available for use by the worldwide general public.

With the help of their onboard atomic clocks, each satellite constantly broadcasts position and time signals. The spacing of the satellites is such that four of them will be available at any point on or near the Earth, and a GPS receiver can triangulate its geographical position (longitude and latitude) from three satellites, and height above sea level from the fourth satellite. For most generally available GPS receivers the location accuracy will be somewhere between 10 to 100 metres, however, with special military-approved equipment, accuracy can be improved to within one metre. Some GPS receivers can also use their display screen to indicate the receiver's position on a map.

GPS is used in a wide range of civil applications, in scientific, maritime and environmental fields. However GPS has found increasing use in personal pursuits, such as hiking, sailing and flying. Vehicle navigation systems are available, and GPS receivers in cars can be used to give traffic and weather information relative to the driver's location. When moving, suitable GPS receivers can calculate speed, travel directions and even estimate time of arrival at a destination.

GPS technology is now low-cost, and increasing numbers of handsets will incorporate GPS receivers, so providing users with the benefits of a location system in mobile equipment. Future UMTS terminals may use GPS to process location-dependent information, or for planned navigation services.