Same trail and very different ascent/descent

Bogdan1921

Hello,
In 2020 I was on an hiking trail and this month I’ve repet it.
In 2020 the data looks good (the peak of the mountain it’s at 2190m) but the data from this year looks not great (big difference on ascent/descent).
The watch was sync before the start, and calibrated. It’s not the first time when I see that this data are not pretty relevant.
Also the watch is updated at the latest version.
What can be the issue?
Thanks

2020: https://ibb.co/fkcLGXX
2023: https://ibb.co/C57yb8P

zhang965

Hello,

No man ever steps in the same river twice.

I’ve just checked my previous runs which are in the same place, I never get similar ascent/descent with S9/s9p/S9PP/SV

Bogdan1921

@zhang965

Yes but the difference is to much:

Ascent for example: 1102 vs 2106

zhang965

@Bogdan1921

I got 60m vs 24m same place in 2 weeks

el2thek

@Bogdan1921 the 2020 graph is a lot smoother. Did you have something covering the watch (like a sleeve) this time. I have read that something covering the baro sensor can cause changes in pressure and as a result affect the altitude reading.

Bogdan1921

@el2thek
Yes, this time I had a long sleeve jacket.

@Bogdan1921 unless it was an air tight sleeve, it shouldn’t matter that much IMHO.

The way altitude gain/loss is calculated might be different between the 2020 and 2023 firmware… wild guess.

zhang965

FusedAlti
FusedAlti provides an altitude reading that is a combination of GPS and barometric altitude. It minimizes the effect of temporary and offset errors in the final altitude reading.

NOTE:
By default, altitude is measured with FusedAlti during exercises that use GPS and during navigation. When GPS is switched off, altitude is measured with the barometric sensor.

https://www.suunto.com/en-gb/Support/Product-support/suunto_vertical/suunto_vertical/settings/fusedalti/

isazi

@twekkel how ascent and descent are compute changed in 2021 with the introduction of a new algorithm, although difference should not be this large. It was very windy and/or rainy this year?

Bogdan1921

@isazi

It was approximaty the same conditions, without rain.

isazi

@Bogdan1921 strange, the alti profile is definitely more nervous in 2023, something was bothering the baro sensor it seems. I would clean the watch to be sure nothing is clogging the sensor from the inside, but it looks like something was pushing air in and out.

Bogdan1921

@isazi

Yes that’s the next step, I will clean the watch and see in the feature how it works. Thanks