by Alain Hoffmann
driver has to know where he is so he can figure out how to get home again.
This task was much simplified when GPS systems came up. In the old time
you had to study maps carefully, work with a compass and draw lines on
What's a GPS?
It's a small electronic unit about the size of an pocket calculator. It
shows you your position in the standard form for navigation. Some units
have built-in maps which might be easier to use..
Please forgive me for using as much the Garmin Emap on these examples.
Besides the fact that I own one it seems to br establishing itself widely
as a new standard for 4wheeling. No, I don't have any financial interests
in Garmin (wish I had).
Above is an example of the Garmin
Emap showing its start-up screen (left) and the 300 Kilometre resolution
(right). Don't worry, most menus can be switched to show English, German
or French (amongst others) text. The data fields on top show the current
speed, the total trip distance since last reset and the precise time.
To the left is a compass rose which changes to an arrow when you are navigating.
The blank line below the data fields shows the name of the next street
to come up when you are moving. All those fields can be switched off so
only a full screen map is left.
How does GPS work?
GPS unit receives signals from satellites. From this signals it calculates
its position. Read here for a basic introduction.
Is it difficult to work with?
Yes and no. Most units will only show you your position as a string of
numbes and letters like N49°37.047,
E006°07.109. This is enough if you have some time to transfer
this on a map. .
Other units have an built-in map on which they show you your position.
This is by far the faster way to see where you are. The drawback of these
units are their price as the built-in memory has to be much larger. Those
units can be mastered in quite a short time..
The last possibility is to connect a GPS receiver to a laptop or a handheld PDA. Those can show an even larger degree
of map details but are also bulkier. Click here to see what a GPS connected to
a laptop looks like. When using it you will also see a moving arrow or similar on the map indicating your position.
Why do I need a GPS?
don't need one. Except if you drive into the Sahara. Or the Australian
Outback. Or an similar remote area where geographical features are not
available. But it's a useful tool. You also don't need 4-wheel-drive most
of the time. But in some cases it comes in mighty handy. This is exactly
the category GPSs fall in.
Above Left: A typical shot in 300
metres resolution. The thick lines show main roads, the thinner the line
the smaller the road. In many countries (like Luxembourg) even a good
deal of the green lanes are shown! To the right is the same part on the
computer screen before downloading to the GPS