GPSs (Global Positioning Systems)
Overview for Long Distance Backpacking
Global Positioning Systems use a network of satellites to triangulate your location, usually within a short distance, like 10'. Terrain can affect satellite reception.
You want as much built-in memory as possible to store maps and datapoints. Removable media, such as SD (secure digital) or MMC (multimedia card), adds to your flexibililty without adding to your weight. Ship maps for the GPS for the next several sections in your resupply. This media can also serve as storage for other data, for instance MP3s.
Manufacturers often make you use their map software. The map CD includes ways to upload a set of datapoints as well as their maps. You can't upload any old maps.
Some, but not all, come with a digital compass, a barometer (which will give you altitude if you are diligent), and other features.
Watch out for battery life.
These can be stand alone units or units to be integrated into a Palm or PocketPC device.
Garmin iQue 3600 information.
Go to http://gpsinformation.net/ for some info.
©2003 John E. Brennan