How Instinct is calculating the correct elevation data?

Hi,

Just found out today that my Instinct is overestimating elevation.

It was calibrated to the correct elevation using DEM data, but then after a while it was showing constantly around 15% higher values compared to maps and another watch. It was also 15% higher when I got back to the starting point of the hike. The trail was rather easy with moderate elevation.

So as far as I know the altimeter is measuring change in air pressure comparing it to the fixed elevation that was recorded upon start.

But how the system would know if the change in air pressure is actually a result of elevation gain and not beause of change in weather?

Oddly enough a Forerunner 735 was spot on within a range of +/- 5 meters.

Thanks,

Adam

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Former Member over 4 years ago +1

8887529 said:
Oddly enough a Forerunner 735 was spot on

Not odd at all since the 735 didn't have a barometric altimeter. Your elevation was based on your GPS location and then it used geographical surveys…

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0 Former Member over 4 years ago

8887529 said:
Oddly enough a Forerunner 735 was spot on

Not odd at all since the 735 didn't have a barometric altimeter. Your elevation was based on your GPS location and then it used geographical surveys to determine your elevation on your 735. What was your barometric pressure pre and post run on your Instinct? If the pressure dropped during your run, or corrected itself to the right pressure because it wasn't calibrated, the watch might have interpreted it as elevation gain. I've included a link that shows the different barometer modes. You can can choose which fits best for your particular activity. As a side note, if you go into Garmin Connect you can enable elevation corrections and it will show your activity with the elevation like your 735 did. It's set to disabled by default for watches with barometers and you would have to do this following every activity if want to use that feature. I hope this helps.

support.garmin.com/.../

0 8887529 over 4 years ago in reply to Former Member

Thank you for your input, the watch is in elevation mode, so any change in air pressure translates into elevation gain (or loss). Hence the question, if I am out on a daylong hike, how the correct elevation is recorded if the air pressure changes?

I've read somewhere that the firmware should autocorrect but not sure...

As for the other watch, it had the small orange icon next to the elevation data, meaning it is based on a sensor (I assume that's what it means).

0 trux over 4 years ago in reply to 8887529

8887529 said:
if I am out on a daylong hike, how the correct elevation is recorded if the air pressure changes?

Theoretically, if you enable the option "Auto-Calibration during Activity", the watch should calibrate using the GPS, or the DEM method. It never really worked very well, usually causing more problems than improving the accuracy, but I did not test it since a longer time, so you may try using the option. Alternatively, you can calibrate the altimeter manually, up and then, while hiking.