GPS tracking uses the global positioning system developed by the U.S. Department of Defense for the U.S. military, which has now been made available to the general public as a free service. GPS receivers allow people with the correct software to monitor the movement of people, vehicles and other assets. Personal tracking is often completed using cell phone coverage from handsets that is now often equipped with personal tracking software.
The Global Positioning System was developed using a network of satellites orbiting the Earth every 12 hours and 24 satellites must be in operation at all times for GPS to work correctly. Three backup satellites circle the planet at all times to provide assistance in case of the failure of an active satellite. The basic concept of GPS positioning is a mathematical concept known as trilateration, which means three GPS satellites are needed to send signals to a receiver to gain an exact fix on the location of the receiver. Satellites require a certain amount of information to fix the position of a receiver, including the distance between the receiver and satellite.
Tracking via GPS needs an active signal sent from the GPS receiver to a database or monitoring station via a cellular telephone network. To track a person, package or vehicle from a remote location the person or organization wishing to complete the tracking must have access to a piece of software designed specifically for tracking. The receiver used must also be equipped with a built-in cellular modem that is used to transmit data on the location of the item being tracked. The inclusion of GPS hardware and software is now commonplace on mobile phones, which has made it easy for the tracking of people carrying a cell phone to be completed. During personal tracking, a signal is received from at least three satellites to determine the exact location of the hardware; the location is then transmitted in real-time to the software user over the network of a cellular network carrier.
GPS tracking is not currently possible without a piece of hardware placed in a location where it can receive signals at all times. In some cases, tracking is completed via a wireless telephone being programmed to receive SMS messages informing the telephone user of the location at specified times during the day and night. Computer software that is loaded with maps can also be used in order to allow tracking via the internet using software accessed via a personal computer.
Source by Terence Liew