crollsurf wrote:Never seen that kind of a discrepancy before. I would normally think give or take 10%. What was the walk if you don't mind?
ribuck wrote:Take a look at your recorded track. Does it zig-zag all over the place? Then, the extra distance is due to the GPS "hunting" around the correct position. Possible solutions include carrying your GPS in a position where it has a better view of the sky (e.g. I put mine in the lid of my pack). I don't know the Fenix 5, but lots of GPS devices and apps have a setting to disregard all GPS points where you haven't moved a certain amount since the last one, and to wait until a GPS point arrives which has a definite and substantial movement (e.g. 20 metres) since the last one. If your recorded track shows lots of zig-zags around your rest stops, that's where the extra distance is coming from, and you definitely need a setting like the one I just described - or you can pause your track recording when taking rests.
ribuck wrote:Your GPS track looks pretty normal to me, so I'm surprised there's such a large discrepancy. The cause is definitely not the 2D/3D issue which you alluded to in your original post. GPS distances are measured in their projection onto a 2D surface, and in any case the difference would be less than 1%.
This is a long shot, since I think you would have noticed, but I don't suppose you accidentally recorded this as an extra segment on top of a previous 6km walk, in which case the total distance would show 27km but the distance for the second segment should show 21km.
wayno wrote:you can get aberations under trees, it does minute zig zags increasing the distance, update your firmware as well, can fix bugs....
Smart Recording saves GPS points when changes in direction, speed, heart rate or elevation are detected. Smart Recording is the default setting of Garmin's watches for the balance it achieves in detail and battery consumption.
Every Second recording will record a GPS point once per a second, regardless of direction, speed, heart rate or elevation. Every Second recording will produce highly detailed tracks of your activities. A more detailed track will lead to more accurate speed and distance data.
If you are looking for the most accurate speed and distance, we recommend using Every Second recording.
wayno wrote:an app like garmin express can specifially pull your latest firmware down connected to a computer via the cable. otherwise using garmin connect can have big delays before it gets the latest firmware
ribuck wrote:I don't know the Fenix 5, but lots of GPS devices and apps have a setting to disregard all GPS points
Dexter wrote:There's a few zig zaggy spots but they are where we stopped for lunch or camp before I paused the walk, and moved around a bit in the one spot.
keithj wrote:Consider uploading your original .GPX file to https://www.plotaroute.com/uploadroute and see how zig-zaggy it looks ?
Dexter wrote:keithj wrote:Consider uploading your original .GPX file to https://www.plotaroute.com/uploadroute and see how zig-zaggy it looks ?
Excellent. I'll give it a look! Would you suggest turning on auto pause? I have always been a little hesitant to trust it.
wayno wrote:Dexter wrote:keithj wrote:Consider uploading your original .GPX file to https://www.plotaroute.com/uploadroute and see how zig-zaggy it looks ?
Excellent. I'll give it a look! Would you suggest turning on auto pause? I have always been a little hesitant to trust it.
depends how much you stop , if you're stopping a lot to admire the view or take photos, theres a bit of a delay before it starts , if you dont stop that often, then no problems. garmin works out how long you were stationary in the resultant trip
Right? I think we've found the route of the problem here.peregrinator wrote:That's not a lunch break. It's a ten-course banquet.
Dexter wrote:I think we've found the route of the problem here.
iGBH wrote:I'd be really surprised it your lunch break explains the extra 6 kms. How long does it take you to normally walk 6kms? Lets assume at best an hour.
So on that basis, your lunch break would of needed to be an hour long walking pretty much flat out without stopping still. Doesn't sound like a lunch break to me.....
Dexter wrote:I think it's any time we stopped, which we do reasonably often (we take our time and enjoy the surroundings, take some photos etc). It likely would have reacted like this each time - so not just for the lunch break. It doesn't seem to always move around at walking pace either, and I have noticed some big speed spikes which I can assume is during these stopped periods. I have increased the GPS ping to 1s, and turned on auto pause. Hopefully that improves it a bit.
keithj wrote:Dexter wrote:I think it's any time we stopped, which we do reasonably often (we take our time and enjoy the surroundings, take some photos etc). It likely would have reacted like this each time - so not just for the lunch break. It doesn't seem to always move around at walking pace either, and I have noticed some big speed spikes which I can assume is during these stopped periods. I have increased the GPS ping to 1s, and turned on auto pause. Hopefully that improves it a bit.
big speed spikes happen when GPS gets a ping that takes longer than it should with a direct line of sight (e.g. under trees, close to cliffs/buildings, overhangs) and it triangulates that you've moved 100's meters between pings. This also adds that extra distance to your track... twice, because when the next correct signal happens, you'll skip back to where you really are. If you had lunch under a tree that may explain it.
You could attach your original GPX file for a definitive answer to the source of excess distance.
IMO increasing the ping to 1s isn't likely to make much difference - or may make it worse!!. Some GPS's or mapping web sites can automatically ignore these points that are 'unreasonable' such as moving at relatively high velocity & subsequently returning to a previous location.
Solutions include -
- avoid walking under the canopy or close to any hard surface a signal can bounce off
- manually pause when you stop (& remember to restart!)
- upload to a gps plotting website & manually delete the 'obviously' dud points
Mark F wrote:The big question is "does a 5-10% change in the length of your walk create problems for your completion or enjoyment of the walk?"
Far more problematic are signs and route descriptions that give very inaccurate distances.
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