Very unusual behavior I observed a while ago in my Garmin Legend. It showed my location correctly on built-in world map, but erred by 9-12 minutes (about 15 miles) in latitute and longitude. This behaviour remained the same when I panned the map on the screen instead of actually moving myself - position of marker on the screen map was accompanied by wrong latitude/longitude, when I compared them to topo-map. World map is poorly detailed, and was useless in this area (and I couldn't use my paper-map either, being offshore, without any specific landmarks in view - and without knowing my position). Luckily, I've noticed this before sailing off and simply used a compass to stay on course. This only happened in some specific world map area - panning other areas showed everything correct. Also, in a couple of days , when I moved about 30 miles away, everything was back to normal. And I know for sure that this particular section of world map was displayed with correct latitude/longitude a year ago. Just have no ideas what might have happened. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Alex, I have noticed similar errors from trip to trip, but only maybe fifty meters or so at most, though. A shoreline will be displaced maybe 20 meters to 30 meters one direction, and a fixed navaid will show as similarly displaced on return to its location. It could be a search of this site may help: http://gpsinformation.net/ It is maintained by two retired aerospace engineers, who have no affiliation with any GPS manufacturer, and who have taken on the task of evaluating and delineating limitations of various receivers. If you determine what is causing this, I would like to know! -- Dave Kruger Astoria, OR ----- Original Message ----- From: "alex" <al.m_at_3web.net> > Very unusual behavior I observed a while ago in my Garmin Legend. It > showed > my location correctly on built-in world map, but erred by 9-12 minutes > (about > 15 miles) in latitute and longitude. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Hey Alex, Three possibilities come to mind: 1. What part of the world were you in? If it's a "hotspot," might the US military, who run the GPS system, be scrambling the signals available to civilian GPS so as not to assist their opponents? 2. Could you or someone else have accidently reset the map datumn in your unit? That's effectly resetting the zero points for the x any axes or lat and long, and might account for the weirdness, especially if a "custom user" datumn were entered. 3. Solar flares scrambling the signals? Cheers, Philip "alex" <al.m_at_3web.net> wrote: >Very unusual behavior I observed a while ago in my Garmin Legend. It showed >my location correctly on built-in world map, but erred by 9-12 minutes (about >15 miles) in latitute and longitude. This behaviour remained the same when I >panned the map on the screen instead of actually moving myself - position of >marker on the screen map was accompanied by wrong latitude/longitude, when I >compared them to topo-map. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
> 1. What part of the world were you in? If it's a "hotspot," might the US military, who run the GPS system, be scrambling the signals available to civilian GPS so as not to assist their opponents? Far from hotspots (Baja), and I can tell you even more - I noticed this error for this particular worldmap area, planning and marking waypoints, prior to flying there from Canada. > 2. Could you or someone else have accidently reset the map datumn in your unit? That's effectly resetting the zero points for the x any axes or lat and long, and might account for the weirdness, especially if a "custom user" datumn were entered. Well, it returned back to normal after a couple of days, without my interference. I confess, I touched "map datum" settings trying to eliminate the error AFTER the error began to annoy me, (changed it from US to Mex) - which was one of my blind and unnecessary actions :-), but didn't notice any changes. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Although, some of your problems are not necessarily related, I suggest a reading of Nigel Calder's, How To Read A Nautical Chart (12 bucks, live a little). It discusses in the chapter, The Limits Of Accuracy, many such problems related to how accurate our charts are and how accurate our GPS units are. If you compound inaccuracies occassionally found in the chart with those sometimes found with GPS, you might see some of the larger variations reported here. Rob G *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Hi all, thought you might find this helpful for some Christmas shopping and river advocacy support, all in one. Happy water trails, cheers, tom RFW Riverwire AUCTION OFFERINGS EXPANDED Release date: November 29, 2004 A womens Wonderjacket 200 lifejacket, Pyranha S6 kayak, a raft frame and a pair of Sawyers new composite oars have joined the mens lifejacket, rafts, inflatable kayaks and a smorgasbord of accessories, books and maps, hotel deals, raft rentals and clothing. If you havent signed up yet, nows an ideal time to register as a bidder and check out the goods at www.rrfw.org/auction.php. Dont wait too long, though, the auction starts at noon, Wednesday, December 1st and ends Sunday, December 5th at midnight, Mountain Standard Time. Support our wilderness conservation and fair access efforts and do your holiday shopping all at once! A big THANK YOU to our terrific sponsors and item donors. Check them out at the website, too, with links from our sponsor page. RRFW would also like to remind people in the Phoenix and San Francisco areas of Grand Canyon National Parks CRMP meetings this week. Both will be held from 4:00pm to 8:00pm. The Phoenix meeting is Tuesday, November 30, 2004 at the Glendale Community College Student Lounge, 6000 W. Olive Avenue, Glendale: www.gc.maricopa.edu/map/. The San Francisco meeting will be Thursday, December 2, 2004 at The Presidio of San Francisco, Presidio Officers' Club, 50 Moraga Avenue, San Francisco: www.presidio.gov/Visiting/DirectionsShuttle/OfficersClub.htm. We will be at both meetings and hope to see you there, too. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ RIVERWIRE is a free service to the community of river lovers from River Runners for Wilderness. Membership is FREE! Send your e-mail address to riverwire_at_rrfw.org and we'll add you to the RRFW RIVERWIRE e-mail list. To join, visit our website at www.rrfw.org and click on the membership link. RRFW is a project of Living Rivers. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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