GPS distance accumulation

I went on a trail run with 3 watches in a winding, wooded trail.
On the left arm was the Fenix 5x and Fenix 3HR. On the right wrist was a 920XT

Strava has runners generally doing about 3.8-4.0

Fenix 5x
3.73 Miles
9% less than 3HR / 4% less than 920XT.
https://connect.garmin.com/modern/activity/1654768150

Fenix 3HR
4.08 Miles
https://connect.garmin.com/modern/activity/1654827632

920XT
https://connect.garmin.com/modern/activity/1654839970

Oh, and yes, GPS+Glonass and 1 second recording.

Kind of bummed, HOWEVER, it was with 2.40 software. will try with 2.9

I am not in the bail out and return it mode right now.

0 Crispin_Ellisdon over 7 years ago

Interesting how the distances vary again once the track lengths are re-calculated in www.mgpsfiles.com/app/. F3HR 4.1 miles and 920XT and F5X 3.9 miles; so the 920XT and F5X closer to the Strava distances you've seen. What's further puzzling, is when I zoomed in on the tracks overlayed on top of each other, none of the tracks have any obvious imperfections that would account for the discrepancy in distance. I also found on one of my early runs with F5 vs F3, that involved some twisty forest trails, the distance was slightly short on the F5 despite the recorded tracks being almost identical (and re-calculated to the same distance in mygpfiles). I've been off running with injury (hopefully back out running soon though) since the 2.72 beta came out with the GPS update, now consolidated in the 2.90 release, so I will be interested how you find distance accrual with the new software. There was no mention in the changelog notes of what the GPS update was delivering, so interesting to see if distance accrual in tough conditions was tweaked.

(I won't post the hyperlink to the mygpsfiles comparison I created from the gpx downloads from your GC activity links; as it's not my data to share/control - if you are happy for me to do so then please say and I'll add the link).

0 indymtb over 7 years ago

Interesting how the distances vary again once the track lengths are re-calculated in www.mgpsfiles.com/app/. F3HR 4.1 miles and 920XT and F5X 3.9 miles; so the 920XT and F5X closer to the Strava distances you've seen. What's further puzzling, is when I zoomed in on the tracks overlayed on top of each other, none of the tracks have any obvious imperfections that would account for the discrepancy in distance. I also found on one of my early runs with F5 vs F3, that involved some twisty forest trails, the distance was slightly short on the F5 despite the recorded tracks being almost identical (and re-calculated to the same distance in mygpfiles). I've been off running with injury (hopefully back out running soon though) since the 2.72 beta came out with the GPS update, now consolidated in the 2.90 release, so I will be interested how you find distance accrual with the new software. There was no mention in the changelog notes of what the GPS update was delivering, so interesting to see if distance accrual in tough conditions was tweaked.

(I won't post the hyperlink to the mygpsfiles comparison I created from the gpx downloads from your GC activity links; as it's not my data to share/control - if you are happy for me to do so then please say and I'll add the link).

Please do! The only thing I want to hide about the data is how slow I was. :)

0 Crispin_Ellisdon over 7 years ago

Please do!

and here it is http://www.mygpsfiles.com/app/#BeP0zQub (the speed is absolutely fine, so nothing that needs hiding there :))

0 phoglund_ over 7 years ago

Interesting how the distances vary again once the track lengths are re-calculated in www.mgpsfiles.com/app/. F3HR 4.1 miles and 920XT and F5X 3.9 miles; so the 920XT and F5X closer to the Strava distances .

It's not so strange I think, In newer watches distance is also calculated with help of the accelerometer in the watches and is saved in the distance track in the fit filé. That is the distance that GC show. Mygpsfile re-calculate the distance only based on gps-track. If the gps i ok, basically this test show that gps is ok, but acceloremeter measurement is worse. A god way of seeing this is with SportTracks and Trails plugin

0 ROGUENODE over 7 years ago

I did a slow 7mi trail run today with a small amount of up and down, a few switchbacks, and some heavy tree cover. I ran with both my Fx and my Suunto A3P. At the end of the run, I had 7.1mi on the 5x (and in GC), and 7.46mi on the A3P. Now, I didn't pause the A3P when stopped off trail to *ahem* take care of business or when I stopped to remove a jacked and stow some gloves, so I expected a bit of difference.

What's more interesting to me is when I drop both files into mygpsfiles.com to compare, they both come out as 7.5mi. It seems the gps file is better than the watch reporting. Wish the watch matched the gps track distance.

GPSFiles tracks