Sebastian Arcus <[email protected]> wrote: > I was looking at the eTrex series from Garmin to use for mapping on > OSM, > as they seem to be robust, compact and have specially long battery > life > (25 hours on 2 AA batteries). The main difference between 20 and 30 > seems to be that 30 has altimeter and compass, while 20 doesn't have > them. Is this important when recording GPS tracks to use for mapping > on > OSM? Doesn't compass and altitude data come from GPS satellites > anyway? > Or an internal altimeter and compass are more accurate? > > If anybody here has either of the above GPS units and uses them for > mapping, it would be useful to hear a first hand opinion. > > Thanks, > > Sebastian > > _______________________________________________ > newbies mailing list > [email protected] > http://lists.openstreetmap.org/listinfo/newbies
The altitude reading on civilian-model GPS units is not particularly reliable; the altitude information from the satellites has deliberate random errors built in, to make it difficult for someone to use a civilian GPS to plan an artillery or rocket attack. The GPS units used by the US military can decode more accurate, but encrypted, altitude data. -- John F. Eldredge -- [email protected] "Reserve your right to think, for even to think wrongly is better than not to think at all." -- Hypatia of Alexandria _______________________________________________ newbies mailing list [email protected] http://lists.openstreetmap.org/listinfo/newbies
