4. Global Positioning System

The way that GPS works is described in the mini-web below

How GPS works

However, this page describes the features of a car navigation system. Car navigation systems can either be built-in by the manufacturer or purchased as an independent sat-nav system. They all offer very similar features. Namely

• GPS signal locates your vehicle on an interactive map displayed on screen
• Maps can be held as DVDs within the car or stored in the devices' internal memory
• Maps cover the UK.
• Other country maps can also be purchased.
• Destination can be entered by post code, street address, list of favourites or indicate on the displayed interactive map.
• Home location can be stored to save having to re-type it in every time
• Intermediate points of interest can be selected, such as airport, city centre etc
• Types of road preference can be selected for the route - motorway, trunk roads
• Type of journey can be selected - fastest, scenic, avoid certain areas
• Can be told to not use minor roads
• As the journey progresses, time left, miles left and distance to the next way point is shown.
• Voice guidance can be selected to avoid looking at the map whilst driving
• Type of voice can be selected - male, female, even celebrity
• If you wander off-course, the sat-nav re-calculates the route dynamically
• Traffic congestion warnings may be integrated, derived from the radio travel news broadcast to the car radio (only with the in-built car systems).
• It may be radio linked to a paid-for commercial traffic advice service to help you decide what to do.

It is important that common sense prevails at all times.

There are tragic stories where the driver ignores clear warning road signs such as 'no right turn' just because the sat-nav told them to do so. Many lorries have run into problems traveling over unsuitable minor roads or under low bridges - again just because the sat-nav told them.