When my Garmin (eTrex Legend HCx) loses signal, it continues logging as if I had continued in a straight line for 30 seconds before either regaining signal or giving up and stopping logging, and I imagine you are seeing something similar.
I see this all the time when going into tunnels and worked around it by postprocessing the logs to drop any run of entries with identical or near-identical latitude and longitude deltas (to within 0.000002 degrees) leading up either to the end of a log or to a sudden change in speed (increasing or decreasing by 10mph in a single second). Eric On Wed, Apr 29, 2009 at 4:39 PM, Jim Ley <[email protected]> wrote: > Hi, > > Last week, and tuesday I did a cycle circuit race, previously (couple > of months ago the tracklog has been > pretty flawless, but both the last two times it was interestingly and > consistently > wrong on every lap, the same errors also happened on my girlfriends > Garmin. The logs were both recorded on a Garmin 705, you can get a > gzipped version of the tcx file here > http://jibbering.com/2009/04/screwy.tcx.gz (or screwy.gpx.gz for a gpx > version of it) > I also uploaded it to http://connect.garmin.com/activity/3973718 From > which you can see that the > Garmin recorded the distance log right (as the speed graphs are pretty > much correct) but the GPS positions were all way off. > > What happened was essentially that in a number of areas on every lap, > the log went crazy, and instead of following where I went, it went in > a weird straight line off course. In the map view of it > http://jibbering.com/2009/04/screwy.jpg or on the > satellite view on the garmin page you can see the circuit clearly, and > previously the logs have been accurately following it, but in both the > last two weeks races > it was just in a couple of parts of the course where it was on course, > the other times being peculiarly off course, with weird straight lines > - not just the ones where it suddenly jumped. > > Anyone have any insight into why this might've happened? Particularly > to two seperate devices. > > Also if anyone can think of a relatively simple way to "fix" the log - > to a reasonable approximation I would be happy. > > Cheers, > > Jim. > > _______________________________________________ > Geowanking mailing list > [email protected] > http://geowanking.org/mailman/listinfo/geowanking_geowanking.org >
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