Clarion MAP680 portable sat-nav

Car owners guide to: Satellite Navigation > Portable Sat Nav

Portable Satellite Navigation became the latest high-tech "must have" for UK consumers as far back as 2005, and the huge demand created a big choice of Sat Nav models within a short time. As the initial surge later eased, prices became even more attractive and the technology and mapping software also improved further, with more "driver's view" 3D style mapping and extra detail on intersections and roundabouts.

Apart from price, the ease of fitting and their portability make these devices especially attractive to the average motorist. Unlike fitted in-car navigation systems, they can be transferred easily from car to car - great if you hire cars for business or on holiday, or if your partner occasionally makes a longer trip in their own car.

While in-car Sat Nav systems need to be professionally installed, portable systems often come with a screen mounted arm and cigarette lighter power cable, making fitting quick and easy, if somewhat untidy.

These portable units tend to have smaller screens, smaller map memory and a less convenient user interface compared to fitted systems. That said, several do give clear 3D colour mapping; the embedded memory capacities are rising as data chip costs decrease; and they are generally easy to setup after the first few trial runs. Where they tend to be less user friendly is during the journey if you need to make quick changes.

The digital mapping may be more simplified (with fewer 'Points of Interest' or POIs) but is generally good, since it all tends to come from the same software mapping companies. You may need to be clued up on how to connect the device to a computer in order to load mapping data into its memory, since they don't have a built-in CD or DVD reader. Some may incorporate an external data reader, such as SD card. Most provide spoken directions but the voice quality may be relatively poor because of the small built-in amplifier and speaker.

The ease of fitting is clearly an advantage since there's no (or very little) fitting cost involved. However, as well as giving a rather untidy appearance and being somewhat prone to detaching itself in strong sunlight, the typical glass-mounted arm makes a very visible target for thieves.

Portable navigation units have replaced the car stereo as the most desirable item for the opportunist thief. Unlike a CD player they are neither difficult to remove or protected by a security code or removable panel.

Even if you religiously remove the device from the arm and carry it with you (not always convenient as some are more portable than others in terms of their shape) the hawk-eyed thief who sees the arm on the windscreen may well break in anyway, assuming that the device will be in the glove-box. Our advice is to always remove the arm from the windscreen when you park.

Summary

In terms of their basic navigational performance, these Sat Nav devices are certainly impressive, up to a point. They really do help to make driving less stressful until, that is, you grow to rely on it too much. It happens to most owners - these things are so nice that you sometimes disengage your own built-in navigation (that is, the one in your head!). If you switch off your own common sense, these things can have you driving up roads normally only navigated by cows!

Such instances are not normally down to poor GPS reception or mapping, but simply the unit choosing the shortest or theoretically quickest route. But these portable units do have some performance limitations.

They generally don't incorporate a gyroscope (this provides information on which direction you're headed, independent of satellite reception) or accept a speed pulse feed (this monitors the car's speed and therefore how far you've travelled since the last GPS position) and so they rely entirely on good satellite reception.

Also, be aware that if your vehicle has a heated or reflective windscreen, you will very probably need to buy and mount a separate internal or external antenna.

A demonstration of any one of the number of fixed Sat Nav systems will highlight the restrictions of many of the portable devices. Their smaller displays, less friendly user-interface, slower calculation time, occasional GPS glitches and - apart from on the upper-end models - lack of live traffic information (TMC) updates become important factors if you expect to use a navigation system on many of your journeys, especially in business travel. But the thing about these portable devices is that they have successfully introduced a huge number of people to in-car Sat Nav and, once you've tried it, you don't want to live without it.