Necessity is the mother of invention so goes the adage. In many of the really innovative and revolutionary inventions, war had been the mother. Global Positioning System or GPS, the very first of the many inventions, is a product that was primarily developed and meant for war. After Russia launched their satellite Sputnik’ in 1957, two scientists in the Johns Hopkins Applied Physics Laboratory in Howard County, Maryland, USA wanted to find a way to predict its position in its orbit. They realized this can be done using the theory of the Doppler Effect. That was the origin of research for developing GPS.
There were lot of earlier developments for specific needs. The developers drew heavily on these systems. Initially, the GPS was exclusively for the defense services only. Later on, it was found to be useful civilians as well. As a matter of fact, the US survey was the first to request for the data and it was made available to civilians by a presidential order. However, the civilians got the application with lesser accuracy. The most accurate positioning data was exclusively for the defense. The GPS was fully deployed by the year 1996, and since then the US has carried out various upgrades. On 1st May 2000 President Clinton ordered the switching off the Selective availability and all stared getting the same data. All nations can use the GPS data with the caveat that America can withhold the use to any nation. Currently 31 satellites are in orbit and working well.
Russians guessed that the use will not be as open as it appears. After all it was developed to target Russian missiles, submarines and other weapon platforms. They developed their own system called GLONASS that resembled the GPS. That system was completed and achieved complete global coverage only by mid-2000. Other nations who have global positioning systems are European Union with their Galileo, China with their BeiDou Navigation Satellite System, India too has a Global Position System with coverage limited to its immediate neighborhood and using 7 satellites.
Global positioning satellites orbit in very precise orbits. Each of them transmits a unique signal having the orbital information. GPS receivers use this information and trilateration to calculate the user’s exact location. A minimum of 24 satellites are required to cover the entire globe.
One of the most popular and easily visible application of GPS in our daily lives is in fleet tracking and individual GPS instruments used by motorists and drivers to drive to desired locations.