How does a GPS work?

The initials GPS come after the English term Global Positioning System. The GPS works by means of a set of satellites that go into orbit in our Planet. Its function is to locate the position of the signal receiver.

The GPS satellites and receivers have an internal clock which registers time through an accuracy of nanoseconds. When the signal is broadcast, the hour when it left the satellite is sent. That signal, which travels at the speed of light, is kept by the receiver which calculates how long it took it to arrive. It is possible to mathematically determine what our position is because we know the position of satellites.

The GPS uses a triangulation system in order to locate the receiver. When we are lost we can ask someone “Where am I? We can be told the following answer: “It will take you 20 km to arrive in Leiria City.” It is obvious that we can be at 20 km whatever direction to Leiria. Thus it is possible to draw a circle having a radius of 20 km (having Leiria City as the centre), so as to determine the area we are placed. The same can be done having in mind other cities and applying the triangulation so as to accurately know our position. It also used a fourth satellite to know our altitude.

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