Global Positioning System
Global Positioning System abbreviated as GPS, is a satellite based radio navigation system. The GPS is also referred to as NAVSTAR. It is headed by United States Government and operated by United States Air Force. GPS receivers receive the signals from other navigation devices. The location of the devices is calculated using the time taken by signals to reach the destination at the speed of light. It consists of well spaced 24 satellites orbiting around earth each with rotation time of 12 hours. There are 4 satellites placed in each of 6 orbital planes. GPS is used in many applications like Airlines, shipping companies, trucking firms, and drivers to track vehicles. Now as the GPS can also be installed on portable devices like mobiles/PDAs, it has become easy to track the stolen devices. The China and Russia are in process of launching new satellite which may improve the accuracy of tracking the locations.