Q:

How does GPS work?

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Quick Answer

A global positioning system, or GPS, works by a process called trilateration. There are anywhere from 24 to 32 satellites, a master control station with four control and monitoring stations and GPS receivers all working together to pinpoint a location.

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Full Answer

Simply put, a GPS system works when satellite signals are intercepted by the GPS receiver. The receiver then calculates how far away the satellites are and uses that information to pinpoint a person's location. Even though there are up to 32 satellites sending out signals, only three signals are required to find a location. This is where the name "trilateration" comes from. However, more satellite signals can be used, and the more that are received, the more accurate the location. The extra satellite signals are used to confirm the signals and location from the first three satellites. The combinations are all tested in order to get a precise result.

Timed signals are used to measure the distance from the GPS to the satellites. When the satellite signals are picked up by the GPS unit, there is a small time lag which is just a fraction of a second. This time lag is converted into distance to each satellite by the receiver. This difference is what is used to calculate the GPS unit's precise position.

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