GPS and Satellite Navigation

Over the last few the popularity of Satellite Navigation systems has rocketed among motorists. Growing demand for 'Sat Nav' devices has led to a major increase in production from a number of electronics manufacturers, meaning consumers now have a wide range of models available to them at appealing prices.

How do Sat Nav systems work?

Sat Nav systems depends on a constellation of 26 US satellites in orbit around Earth. These are known as the Global Positioning System (GPS)*. Signals being constantly beamed to earth from each satellite can be read by the receiving equipment in your Sat Nav unit, and as long as the receiver can read the position of at least three satellites it can locate its exact position on the surface of the earth using a process of mathematical triangulation. Using sophisticated digital mapping and some clever software, the position is then laid over a standard road map which accurately reveals your vehicle's position to within ten metres.

Built-in software can also calculate the easiest route between any two points on the map and can combine average road speeds and other data to advise you on arrival times and road conditions.

A few Sat Nav devices also offer basic traffic information for free, but with most, traffic information is an optional extra, paid for via a one-off fee, or a monthly or annual subscription.

*GPS is run by the US military and is currently the only fully functional Global Navigation Satellite System (GNSS) in the world.

Which Sat Nav is best for me?

There are many different types of satellite navigation devices on the market. Deciding on which one to go for depends on the following criteria:

Portable or fixed

If you need to move your Sat Nav between vehicles then you should opt for a portable Sat Nav system. These devices can be used in any car - even hire cars abroad - and can also be taken on walks. However, if portability isn't an issue and you require a more sophisticated device that is also less vulnerable to theft and loss, then a fixed or 'hard-install' Sat Nav system would be more suitable.

Where you travel

Do you need a device with European or USA mapping software or do you only travel within the UK?

What extra features you require

Do you require features such as a built-in MP3 player, built-in Bluetooth, touch-screen controls, hands-free calling, speed camera detector, points of interest locator, traffic updates, widescreen display, an internal hard drive (useful for storing and updating map data), etc. Remember, the greater the specification the more expensive the unit.

Sat Nav Makers

There are many Sat Nav brands on the market. The most popular include TomTom, Garmin and Navman, which all use the latest and most advanced GPS software technology in their models.

Other brands include Sony, Snooper, Mio, Medion and Navigon.