How they work

A hand-held GPS is a cellphone-sized gadget that can tell you exactly where you are, anywhere in the world. It can also show you a map of where you are, and then tell you which way to go next.

GPS units bounce signals between orbiting satellites. The more there are in the sky above you at one time, the more accurately it will be able to pinpoint your coordinates.

A minimum of three satellites is required for a location fix (aka “signal acquisition”). You need to factor this in next time you’re taking a GPS on your tramp – will you have access to open areas where you can see a lot of sky? Foliage, bad weather (such as snow or hail), cliffs and other obstacles all interfere with a proper reading.

Tip: Treat your GPS unit as an aid to your navigation – you should still have knowledge of basic map and compass reading.