Group test: Satellite-navigation systems

Satellite-navigation devices are sure to top many Christmas lists this year as their popularity goes through the roof. The boom can be attributed to improvements in accuracy and huge reductions in price.

Over the next few pages, we’ll explain the ins and outs of the technology and provide a close-up look at 10 of the very latest products available, showing you the sorts of things you should be looking for in a perfect sat-nav device.

Got straight to our reviews. For comparison tables see the pdf.

What is sat nav?
To put it simply, satellite navigation is a technology that enables you to pinpoint your location by locking onto radio signals sent by a network of satellites orbiting Earth – the Global Positioning System, or GPS.

Each satellite houses an extremely accurate atomic clock and continuously beams the time towards Earth. By locking onto several different satellite signals, a GPS receiver can quickly calculate its own latitude, longitude and altitude, accurate to within a few metres.

Combine this with the appropriate navigational software and it is possible to literally see where you are on a moving map in real time, plot a route to your destination and even receive voice directions at every turn.

Originally developed for military use, the US Department of Defense-run GPS satellite network is now used by countless people in countries across the world. It’s an integral part of many industries, from shipping and aeronautics to the emergency services – and even land surveying.

The US government made the decision to offer the GPS network for civilian use for free, hoping this would speed up the evolution of the technology – and it certainly has. New, improved satellites were launched last year, and a brand-new system that will use signals from the new European Galileo satellite network is currently under development.

Setting up
There are three varieties of in-car sat-nav devices available to help you get from A to B: the built-in sat-nav system; the GPS add-on upgrade kit for an existing device (such as a mobile phone or a handheld PC); and the dedicated GPS device.

A high-end motor vehicle, for example, may have a satellite navigation system pre-installed. If you own a compatible mobile phone or handheld PC, on the other hand, you may be able to cobble together a sat-nav device by adding a GPS receiver upgrade and navigation software.

For most people, though, the best bet is a dedicated portable GPS receiver with a built-in navigation system.

These are available in a range of shapes and sizes and are, for the most part, easy to fit: just mount the device on the dashboard and plug the power cord into the car’s cigarette lighter. It’s this device of system that we will focus on in this round-up.

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