GPS Technology Essays

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Physics Assignment Global Positioning System GPS, of the Global Positioning System, is a system of satellites that orbit the earth above us that send signals continuously to ground stations that monitor and control GPS operations. GPS signals can be detected by GPS receivers, which by itself can calculate the location of the receiver by around ten metres. Such the accuracy and reliability of the GPS system that its is a required item for a long trip without and contact with humans. The GPS system was originally intended for military use; its use was to track and detect ships and submarines by the US military in the 1960s. As time moved on, and as the development progressed, its use changed, from only a military use to a more civilian…show more content…
The receiver compares its own time with the time sent by a satellite and uses the difference between the two times to calculate its distance from the satellite. (Light travels at 186,000 miles per second: if the satellite time happened to be, for example, one-thousandth of a second behind the GPS receiver's time, then the receiver would calculate that it was 186 miles from that satellite.) By checking its time against the time of three satellites whose positions are known, a receiver could pinpoint its longitude , latitude , and altitude. The method just described would require that both the satellites and the receiver carry clocks of remarkable accuracy. However, having a receiver pick up a signal from a fourth satellite allows the receiver to get by with a relatively simple quartz clock--like that used in most watches. Once the receiver has made contact with four satellites, the system takes over and computes its position almost instantaneously. For the system to work, the receiver has to know exactly where the satellites are and the satellites have to be able to keep reliable and extraordinarily accurate time. Accuracy is ensured by having each satellite carry four atomic clocks, the most accurate timing devices ever made. Reliability is ensured by the satellites' 11,000-mile-high orbits, which put them far above the atmosphere
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