Using a Garmin Etrex GPS with Linux, in France


I've been enjoying some trekking in the mountains, lately, and I've been interested in playing around with a GPS device. I've bought the Garmin Etrex, was 212 euros in 2002, kinda good price compared to the competition (but it already failed two times - suddenly, doesn't switch on anymore :( - so I'm not sure I would advice it to you).

One important problem dealing with GPS devices is the format in which the positions are handled. Each country has more or less invented its own way of projecting earth positions to maps, ending up with a shitload of incompatible systems. In France, the National Geographic Institute doesn't want to sell electronic maps suitable for GPS upload, and has only recently accepted to add the UTM/UPS positions to their 1:25000 trekking maps.

After buying a cable to connect my PC to my GPS device, and using the nice program gpspoint to transfer data under Linux, I've discovered that data transmission will only be done in WGS84 latitude/longitude in degrees. Problem being that converting these coordinates to/from UTM/UPS is quite complicated...

Gpspoint's author directed me to a nice guy, Johan Montagnat, who wrote some Java code to convert positions values from/to various formats. I've extracted the WGS84 <-> UTM code and converted it to a small Perl script you may find useful to download. Using it is straitforward. Hope it helps.


Last updated: Fri Apr 25 11:50:22 2003
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