This section aims to bring you providers and retailers of in car navigation systems, both GPS and Satellite based. Designed for easy fitting in your car they will enable you to find your destination safely without using a map. Plotting your route using satellite or GPS navigation technology, using an inbuilt road map and knowledge of your cars speed and position to ensure that you take all the correct roads to reach your destination, also included are systems that will warn you of traffic conditions to ensure you do not encounter any delays.

How Satellite Navigation (GPS) Works

The Global Positioning System (Sat Nav) relies on 24 satellites in orbit at 11 000 nautical miles above the Earth in six orbital planes, each containing four satellites. Conceived as a military navigation system by the US Government, civilian usage has dramatically increased in recent years. In 2000, the ‘Selective Availability’ feature that degraded the accuracy for non-military users was switched off.

Each satellite takes 24 hours to complete one orbit of the Earth, and they are arranged such that at any one time at least four satellites are visual to a GPS receiver with a clear view of the sky. Tall buildings and trees can obscure reception of the signals.

Decoding the signals from the visible satellites, a GPS receiver can accurately calculate its position to within a few metres using a triangulation method. With enough satellites in range, it can also indicate altitude.