Garmin Footpod autocalibration

Former Member over 8 years ago

Hello,

I'm wondering whether the value of autocalibration is shown in the menu just as is it when entering manually the calibration factor for the Footpod. Does anybody know?

Right now it seems that the calibration factor did not change although it should have. Apparently my current cal. factor is actually too high - I entered it manually after running a supposedly measured track. Then I ran somewhere else where I was given a certain distance ran based on the GPS reading ("Footpod indoor only" and "Auto calibration off") while the Footpod was only showing the speed.

A couple of runs later I wanted to cross check how much the distance differ between the GPS and the Footpod. That there is a difference is easily possible because the nature of the ground with the manually entered cal. factor is gravel and that of the recent running trails is mulch. It turns out that the Footpod gives a higher distance on the gravel. Also, I tend to trust the GPS value because its result was rather consistent during the last couple of identical running trails.

It follows that the cal. factor for the Footpod is too high for that one type of ground. After the running session with "Autocalibration on" the cal. factor didn't change nominally, it's still the same as before.

0 loaruns over 8 years ago

"trails" may be your issue.

Garmin footpad calibration used to be a hot topic- it never seemed to happen, but it has gotten better. There are some minimum requirements, however:

You need to run at least 20 minutes without stopping
GPS reception must be high quality and uninterrupted
You should be running in a relatively straight line.

The last two are less likely with trails.

Good luck.

0 Former Member over 8 years ago

Crispin Ellison is the guy you need to talk to. :-)
I saved a thread where he explains lots of things in view of the taking of the foot pod (which has been in its box for a year now). I hope it helps: https://forums.garmin.com/forum/on-the-trail/wrist-worn/fenix-3/138157-?357420-Footpod-calibration-factor-changes-value-walking-vs-running=

0 Crispin_Ellisdon over 8 years ago

Z-74 is probably bigging me up more than I deserve; others out there have lots of knowledge on this too. From my experience of Fenix 3 and 5, the foot pod auto calc calibration factor (CF) feature requires some/all of your run to be at a steady pace, with reasonable GPS reception and on flattish ground. Exactly what the trigger in the device software is for accepting or rejecting data to determine a new CF, only Garmin and your selected deity know. So, if you're finding the Auto Calc CF is not working for the sort of runs (trail) that you are doing, then record a run with the Speed/Pace set to Always and Distance set to Indoor or Off (so that recorded distance is from GPS). Extract the .fit activity file and use the Fellrnr tool here http://fellrnr.com//Utilities/Calibr...ation_beta.exe . By default the tool compares the recorded pace from the foot pod with the recorded distance from GPS to give you a new calibration factor adjusted from the current one you enter (just remember a CF of 98.5 on the Fenix is a CF of 985 in the tool). The tool even allows you to zero in on a specific portion of your run (manual lap key is your friend here) and enter a known distance if you don't trust the GPS distance recorded to the .fit file (highly likely if you're running on twisty trails in the woods where the Auto Calc CF doesn't work). More detail on the Fellrnr site here http://fellrnr.com/wiki/Garmin_Foot_Pod_Calibration . Also, I haven't used the tool in a while, so I don't know whether it copes with the very latest .fit file formats.

0 Former Member over 8 years ago

You people have accepted "trails" as if I was running the Alps frequently :p
Which I'm not.

Both different running "routs" are located in two different city parks and it's flat as Earth is flat (in a relative way). The only thing that really sets those two parks apart is that one has gravel and the other mulch.

Given that every time I go for the jog I give the watch plenty of time to say hello to all the satelites and that jogging in parks involves trees and curves, I guess I'll never experience the autocalibration thing.

So, my workaround was simply to compare the two measured distances by GPS and the footpod and then apply it to the calibration factor formula:
actual distance/measured distance*current calibration factor=normal calibration factor

actual distance=value measured by GPS and kept in mind
measured distance=value measured by footpod and shown on the watch
current calibration factor=CF in use by the watch
normal calibration factor=desired true CF

0 phoglund_ over 7 years ago

New question on the same topic:
Is it possible to have both the distance measured from pod and GPS to be saved to the fit file with an app or data field?

0 Crispin_Ellisdon over 7 years ago

Yes. Both the Fenix 5 series and Fenix 3 before still records the GPS track regardless of whether the foot pod settings are configured for pace and/or distance to come from the foot pod.