GPS Devices - How Do They Work?

Unless you've been living under a rock, you certainly have heard of the Global Positioning System or GPS. There is a GPS for almost everyone: for hikers, drivers, bikers etc. You also find GPS modules on some advanced mobile telephones like the Nokia 6110 Navigator.

What is it?

In very simple terms, the Global Positioning System (GPS) uses radio signals from 4 satellites to locate the exact position of anything on Earth.

What does it cost?

Apart from the cost of buying one, using a GPS is free of charge. In fact some of the most basic GPS do just what they are about: guiding the driver from A to B via a graphic interface.

The most recent models come with a range of functions (MP3 player, slideshow, video player, blue tooth kit, and even digital TV!).

Some GPS have pre-installed POI (points of interest) such as garages, restaurants, parking etc. GPS makers have also added new value-added services such as live traffic update or a weather services like Tom-tom Weather on the GO 530/730/930).

You will need a subscription to most of those services however. Typically an annual subscription costs around $50, with unlimited updates.

Other options are free for a limited period only (for instance when a new map becomes available within 30 days of buying a new GPS, Tom-tom will let you download the map free).

What to look for?

• Ease of Use. If you are not too comfortable with gadgets, you might prefer going for a simple model. One that simply guides you from A to B without all the extras.

• Traffic Info. Some GPS offer real time info on traffic jams or road works. The GPS then recalculates your route - and offers an alternative one. These services are often charged so you'd better check before buying!

• Speed Cameras. Most GPS's come with a pre-installed list of speed cameras. And again here, you will need some form of subscription to update that list with new cameras.

• Maps. Some GPS only cover a limited geographic area. Others have more extensive maps like the Tom-tom Go 730. This type will be particularly useful for your holidays abroad. New maps can also be purchased as CD ROMs or on pre-loaded memory cards.

You can also download off the website of most GPS makers. After download, you then transfer the maps onto the GPS using either a memory card, a USB cable or a Bluetooth kit (if your GPS has Bluetooth).

• Screen Size. This usually varies between 3.6 and 4.3 inches. As a rule, especially for car GPS, information on the screen should not be too hard to read. But this should not be a problem considering that most new GPS's come with voice navigation.

By Amene Katanda