GPS is an acronym for Global positioning system. Technically GPS is a network formed by connecting various satellites. This network is used to determine the location of the user on Earth. The device used to determine the position of the user is called a GPS receiver. For example when we use our phones to determine our location on Earth through GPS – our phone is acting as a GPS receiver.
Not only position on Earth, GPS receiver can be used to determine the movement of the user. The direction, speed, height etc. can also be determined. GPS receivers nowadays are preloaded with data like road maps, hotel locations, gas station locations, coffee shop locations etc. Such GPS devices are mainly used by people travelling by automobiles. Similarly there are GPS receivers for those travelling by air and water. Such GPS devices are nowadays majorly used by people to plan their journey.
How does GPS work?
There are about 30 satellites orbiting around the Earth. A GPS receiver can receive radio signals from about 6 to 12 satellites at a time. These radio signals contain accurate time and position of the satellite. Each satellite has an atomic clock set by NORAD. This clock is set several times a day. After receiving a radio signal from a satellite the GPS receiver calculates the time difference between the sending time and the receiving time.
GPS receiver then makes mathematical calculations to determine the distance of the satellite from itself. It also calculates the angle between the satellite and itself by using the positions and distance of the satellite. The receiver then performs trigonometric calculations using this angle value to determine its exact location on Earth. Usually GPS receiver needs radio signals from at-least four satellites to accomplish the above mentioned calculations. A GPS receiver can calculate its position through above process many times in a single second thus the change in these values helps the GPS receiver to calculate its speed and direction.