The GPS refers to Global Positioning System. GPS is a space based global navigation system provided by United States' Department of Defense at free of cost. Using this system, you can access one’s or your exact location on earth at any time any day without bothering the weather condition. The GPS system works on three segments – Space segment, Control Segment and User Segment.

Space Segment comprises orbiting GPS Satellite or Space Vehicles (SV) and monitored, operated and controlled by US Air force. The Control Segment composed of a master control station (MCS), an alternate master control station, four dedicated ground antennas and six dedicated monitor stations. The control segment is based on various positions on the earth besides US territory.

The User segment comprises an antenna, receiver-processors, a highly stable clock (often a crystal oscillator) and a display for providing location and speed information to the user. A single receiver can monitor various satellite channels simultaneously and usually describes the number of channels.