| Have you ever been lost, chances are you always have a fairly good idea of where you are.
With satellite navigation devices, also known as GPS you can pin point your location to within a few feet of where you are.
Sat nav uses the Global Positioning System, a net work of satellites which transmits signals to receiver equipment on the ground. At least 24 satellites are in operation around the world at any time.
A sat nav system in a car receives signals from several satellites at one time to triangulate a precise location. This information is combined with Mapping information in the sat nav system to establish the exact position of the car and calculate the route.
If you move, the GPS co-ordinates change and the map is plotted again.
The software within the system plans the best route to your destination, taking into account any factors you specify, such as avoiding toll roads or motorways.
Sat nav systems with traffic modules have the ability to alert you to busy, congested roads and some can re-route your journey to avoid these. The traffic information is supplied via a separate service to the GPS.
Most sat nav screens Offer simplified views of just the roads, this is easier for driving.
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