GPSs are the key aid to navigation, allowing a civilian or military receiver to determine their precise location (longitude, latitude and altitude).
GPS is funded and controlled by the US Department of Defense (DoD). GPS provides specially coded satellite signals that can be processed by a ground receiver that contains an embedded digital signal processor.
GPS positioning is based on measuring the travel times of radio signal emitted by satellites to a receiver mostly located on the ground. These travel times can be obtained by measuring on the precise but ambiguous, GPS carries phases or on the, less precise GPS PRN codes.
The satellites are equipped with an atomic clock and radio equipment to broadcast a unique signal, called a ‘pseudo-random code,’ as well as ephemeris data about the exact location position of the satellite relative to Earths and astronomical reference frames.
The GPS concept was conceived by Ivan Getting (1912-2003) in the 1960s while he was –president of the Aerospace Corporation. Bradford Parkinson led the engineering team that developed the first experimental system in 1978.
GPS systems are used in archeology, oceanography, geographic, information systems, mining, space exploration and many other fields. The GPS has significantly enhanced functions such as mapping, aerial refueling and rendezvous, geodetic surveys, and search and rescue operations.
GPSs have been integrated into marine navigational systems, allowing for determination of position, speed, bearing, distance or travels, etc. Commercial and recreational operations have been revolutionized, effectively replacing the use of printed nautical charts.
Global Positioning System
