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GPS (Global Positioning System)

GPS is made up of a system of satellites operated by the US Department of Defense.

GPS is based on a total of at least 24 satellites orbiting the Earth and continuously transmitting signals of their position and time. The GPS receiver receives this data and calculates its own geographical position on the basis of the information broadcast by the various satellites.

Data from at least three satellites is required for positioning with an acceptable degree of accuracy. With data from four or more satellites it is possible in addition to determine the position's altitude above sea level. Positioning is accurate to within three meters. Once the navigation device has determined your position, this position can be used as a starting point for calculating a route.

The map data on your navigation device includes the geographical coordinates of all digitally recorded points of interest, streets and places. This enables the device to calculate a route between a starting point and a destination. Calculation of the current position and its representation on the map takes place once every second. In other words, your current position is always shown on the map.

When the GPS receiver is switched on for the first time, when it has been switched off for a long time or when a great distance is covered between it being switched off and back on again (e.g. after a flight), it must receive a complete data set from each satellite before it can calculate its position. This can take several minutes.

This entry was last updated on: Friday, October 17, 2014 1:37 PM

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