+badger10 Posted September 5, 2012 Share Posted September 5, 2012 A friend of mine is having problems with his GPSMAP62ST. He went on a hike up around Bumping Lake (Washington State) and had between 20-200 feet difference on his track. The 62 is set to true north. I can see 10-20 feet difference but 200 plus feet on a hike. This is on a road or improved path and not bushwacking. The path is on the base map that came with the 62. It is up to date and the compass is always calibrated. The compass is set to auto so I don't know if that would cause that much of a difference. Any ideas? Quote Link to comment
+Atlas Cached Posted September 5, 2012 Share Posted September 5, 2012 Oh yeah. The basemaps that are pre-loaded on the Garmin GPSr are commonly off by as much as 300 feet, or more. Try loading some real maps from GPSFileDepot. Since you are in WA state, I don't think you will find anything better than Northwest Topos. Quote Link to comment
tr_s Posted September 5, 2012 Share Posted September 5, 2012 Actually, that sounds normal to occasionally see even on a 1:25 000 topo, even if it's on the high side. At least some topos have been poorly vectorised from the raw data resulting in those types of discrepancies, or the data was old/imprecise/not that good in the first place. Quote Link to comment
Grasscatcher Posted September 5, 2012 Share Posted September 5, 2012 Another way.... Try to re-do the hike and GPS it again if possible. Now......does the GPS repeat with itself? ie,duplicate the first results reasonably closely? Maybe it's the map(s) that are incorrect not the GPS. You can narrow it down pretty quickly. Also, depending on the terrain, incorrect results can be a result of "multipath" error which is caused by reflected satellite signals.....hiking in a canyon, or close to a cliff face etc. Quote Link to comment
+Viajero Perdido Posted September 5, 2012 Share Posted September 5, 2012 When the map and the terrain disagree, believe the terrain. (My favourite tagline.) The path under your feet is real, and the track log your GPS unit recorded should be pretty close to reality. Trails on the map, not so much. Those are often based on old data, perhaps from aerial photos, or even wild guesses. Quote Link to comment
+Atlas Cached Posted September 5, 2012 Share Posted September 5, 2012 (edited) When the map and the terrain disagree, believe the terrain. (My favourite tagline.) I like it! I'm gonna have to use that one As obvious as it sounds, we still have people trust their GPS first and drive off bridges..... Edited September 5, 2012 by Atlas Cached Quote Link to comment
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