Group test: Satellite-navigation systems

We test 10 of the best sat-nav stocking fillers

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.

Dimensions
Like almost everything in the world of technology, GPS equipment is getting smaller. The best sat-nav devices, however, find a good balance between screen size and physical dimensions. For security reasons a removable sat-nav unit has to be small enough to slip into a pocket or handbag easily when you get out of the car.

Pocket-sized proportions shouldn’t come at the cost of screen size, though. The display needs to be big enough for the driver to view clearly – although we should point out that it’s unwise to be squinting at these things while you’re actually driving.

It’s not just the size of the screen that’s important, either. It should be bright enough to be viewed clearly in daylight, colourful enough so that elements of the map can be differentiated between and, preferably, feature some kind of anti-glare protection.

For most GPS devices, the screen isn’t just there for show, it’s also the main way of interacting with the unit. The majority of sat-nav products use touch-sensitive displays. Some budget GPS systems rely on buttons or joypads to navigate through the functions, menus and settings, but it’s easier if you can just tap in what you want onscreen.

Some expensive sat-nav devices accept voice commands, but that technology is still a little way off for cheaper GPS products. It’s more likely that the machine itself will be doing most of the talking. Many such devices can dictate directions, audibly instructing the driver when to turn left or right.

Maps and storage
As well as the hardware, the other key aspects of a sat-nav device are its software and maps. Most work in a similar way, with a simple Windows-style user interface that can be navigated via the touch-screen. You’ll find icons representing certain functions – a spanner icon for the settings page, for example, or a folded map icon for the map page.

In the worst cases, it is possible to get a little lost while trying to find your way around the menus. More helpful models may offer features such as predictive-text systems, which is handy when tapping in long addresses.

There will usually be some kind of map included in the package (UK street-level maps, at the very least), and further maps can be purchased separately. These are often sold on memory cards that can be slipped into the relevant slot on the device. Sometimes, however, the GPS device may need to be connected to a PC to transfer maps from a CD-Rom to the unit’s internal storage.

When it comes to planning a journey, the best sat-nav systems will offer a choice of routes between two points, as well as providing the option of stipulating additional stops along the way or specific areas or roads that you want to avoid.

This is really handy for van drivers and caravan towers who might otherwise find themselves directed down roads that are too narrow.

Locations can usually be found by doing an address search. Even better is a system that allows you to search for locations using a UK postcode. Strangely, this feature isn’t as widespread as you might think.

You should also find that it’s possible to plot your route via particular points of interest (POI).

This could be anything from a petrol station to a museum. Since the POI – and, indeed, maps in general – are prone to change over time, you may need to update them regularly, although this kind of service is often only provided via an additional subscription or one-off fee.

Because GPS devices work via direct line of sight to the satellites orbiting above us, coverage can be an issue. In a lot of cars, positioning the device directly beneath the windscreen will allow it to communicate with the satellite signal unhindered for most of the time.

Some types of windscreen glass may require you to fit an external GPS antenna, but this is not common.

More prevalent is the loss of signal caused by tunnels or dense overhead foliage. These days, GPS devices have systems that can compensate for the loss of satellite signal for up to 30 seconds. Any longer and the device may need to re-establish a lock on the satellites, which can take a couple of minutes.

Security
Car crime has increased around the country at a suspiciously similar rate to that of satellite navigation’s rise in popularity. And it doesn’t take much to work out that an expensive electronic gadget left on display in a vehicle’s windscreen might be something of an enticement for the average thief.

As manufacturers cotton on to this aspect, more and more are introducing security measures into their products. The majority, however, involve only a simple PIN code lockout.

Far more effective is removing temptation altogether by taking the GPS system with you whenever you get out of the car. We advise removing all trace of the device completely, including its cradle, cabling and even any suction marks on the windscreen.

Among the more useful extras are traffic alerts and warnings about the locations of speed cameras. Both may require ongoing updates, however, and many manufacturers offer these services only as part of a subscription-based added option. Others may include a month, a year or even a lifetime of free traffic alerts and speed cam updates.

There’s also a growing trend for including bonus applications, some more relevant than others. An electronic address book or imperial-to-metric converter might be quite useful, for example. Multimedia functions, such as a built-in mp3 player or photo browser, may be less pertinent but handy nonetheless.

This article is part of a group test of satellite-navigation devices.
See also: 
Garmin Nuvi 310
Magellan Roadmate 3050T
Medion GoPal PNA465
Mio Digiwalker C510E
Navman N40i
Navsure 300i
Novogo S700
Sony Nav-u Nv-U5 0T
TomTom One Europe
ViaMichelin X-950T
When sat nav goes wrong
Galileo project

A table of features can be read via our pdf download above.