GPS

A GPS tracking unit is a device that uses the Global Positioning System to determine the precise location of a vehicle, person, or other asset to which it is attached and to record the position of the asset at regular intervals. The recorded location data can be stored within the tracking unit, or it may be transmitted to a central location data base, or internet-connected computer, using a cellular (GPRS), radio, or satellite modem embedded in the unit. This allows the asset's location to be displayed against a map backdrop either in real-time or when analyzing the track later, using customized software. Such systems are not new; amateur radio operators have been operating their free GPS-based nationwide real time Automatic packet reporting system [APRS] since 1982. The Global Positioning System (GPS) radio occultation (RO) technique offers a valuable new data source for global and continuous monitoring of the Earth’s atmosphere.