The Global Positioning System (GPS) is a navigation system consisting of a network of 24 satellites. These satellites are placed into orbit by US department of defense. It was intended basically for military use though in the 1980’s it was allowed for civilian use.

The GPS works 24 hours a day, everywhere in the world, in any weather conditions. One can use the GPS without any charge.

GPS satellites orbits the earth twice in a day in a set orbit and are engaged in transmitting signals to the earth. Receivers use this transmitted information to decide the location of the person. Basically it calculates the difference between the time the signal is sent by a satellite with that taken to receive it. The difference in time reveals how distant the satellite is. Next the distance from some more satellites is measured and the receiver is able to determine the exact location of the user.

A GPS recover must be attached to the signal of minimum 3 satellites to determine 2 D position (longitude and latitude) and keep track of his movement. With 4 and more satellites, a 3 D position can be ascertained (altitude also). Once location is established other data like speed, distance etc can be calculated.

GPS is free for everyone. Anyone with a receiver will be provided location and time. The GPS consists of three sections: Satellites circling the earth, earthly monitoring and control stations and GPS receivers.

One can purchase GPS receivers readily available in the market. With these receivers one can correctly place where one is and easily proceed to your destination whether by driving, boating or flying.

GPS has evolved to a main transportation system, providing direction for ground, aviation and maritime movements. Emergency services rely on GPS for timing and location services to help support rescue missions.

Accurate timing provided by GPS helps in operations such as mobile phone operations, power grids control and banking operations. Farmers, scientists and many others perform their functions efficiently using GPS signals.

There are some factors that degrade GPS signals and affect accuracy of their readings: They are Ionosphere and Troposphere delays, receiver clock errors, orbital errors and purposeful degradation by US department of defense for defense purposes.