The system of knowing one's exact position on this earth is known as the 'Global Positioning System'. Precise positioning of any location can easily be done with the help of this System. If anyone has a Global Positioning System receiver and if the sky remains clear then no one is going to be lost on this Earth. The receiver is a pocket-sized gadget that makes us inform about our exact position on this earth at any moment. One thing is that this pocket-sized gadget or receiver is very expensive and it also involves a lot of technical ingenuity.
The primary function of Global Positioning System is the navigation in three dimensions. The Navigation receivers are used for aircraft, ships, and ground vehicles and sometimes it is also carried in hands by individual.

The working of the System

The GP System provides some special satellite signals which is processed in the receiver. These GPS receivers not only track the exact location but can also compute velocity and time. The positions can even be computed in three dimensional views with the help of four GPS satellite signals. The Space Segment of the Global Positioning System consists of 27 Earth-orbiting GPS satellites. There are 24 operational and 3 extra (in case one fails) GPS satellites. These satellites move round the Earth in 12 hours and send radio signals from space that is being received by the GPS receiver.
The control of the Positioning System consists of different tracking stations that are located across the world. These monitoring stations help in tracking signals from those GPS satellites that are continuously orbiting the earth. The Space Vehicles transmit microwave carrier signals. The users of the Global Positioning System have GPS receivers that can convert the satellite signals by which one can estimate the actual position, velocity and time. Four satellites are required to track the three dimensional location and time.
The operation of the system is based on a simple mathematical principle called Trilateration. The Trilateration may be of two types i.e. 2-D Trilateration and 3-D Trilateration. In order to make the simple mathematical calculation the GPS receiver should know two things. Firstly the location of the place is to be traced by at least three satellites above the place. Second is the distance between the place and each of those Space Vehicles. Units those have multiple receivers can pick up signals from several GPS satellites at a same time. These radio waves are electromagnetic energy that travels at the speed of light.

Overview

GPS is specially a Satellite Navigation System that helps in tracking the exact location with the help of satellites. The Global Positioning System is mainly funded and controlled by the U.S Department of Defense (DOD). The system was initially designed for the operation of U. S. military. But today, there are also many civil users of GPS across the whole world. The civil users are allowed to use the Standard Positioning Service without any kind of charge or restrictions.