Roles of Gps

Global Positioning System
The global positioning system, which is more commonly known as the GPS, is now a common used piece of technology in our everyday lives, with phones, cars and machines all utilising the device. It is used in many ways, from navigating a plane or just finding out where you are.
Where did the Come From
The GPS was in use many decades before ordinary civilians had access to the technology, with the first use of the device in 1960, in which the United States were using the idea for navy and army purposes. 1 The GPS was eventually developed and over approximately one or two decades, it was put to use for both military and civilian uses. GPS devices, which were used back in the 20th century, were only accurate to about one hundred metres whilst with the advancements in technology, the GPS is only   a couple of metres behind 2,3. The GPS had seen its first ever civilian use when Korean Airlines Flight 007 strayed off course due to a faulty INS system and was eventually shot down by the soviets. 6
How does it work?
A GPS works through a process called triangulation, where three satellites orbiting around earth each pinpoint a specific point on earth through a series of network triangles and then the waves that the GPS emits are reflected back off the satellite. With this information, the device is able to almost pinpoint the exact information using the time it takes for the wave to reach the satellite and back. This is done and repeated to through three satellites, where the GPS device undergoes a process called trilateration, where circles are drawn from each GPS (the GPS can detect how far away a GPS is from the ground and hence determine the radius of the circle). This is done three times to three different satellites and the exact location is drawn where the three circles from the three different satellites intersect 5
However, for the GPS to also measure the altitude, four satellites need to be used.4
The information that GPS use are...