Problema altimeter

[VoiGAS]

@marcos Did you use it starting an exercise or just as a display on the watch?
If you start an exercise the altimeter will calibrate itself during the first 10 minutes or so.
Without starting an exercise you have to calibrate it manually - that would be normal behaviour

[flo7z]

hello.
I am also experiencing “big” altimeter changes (values changes from 490m - after calibration with the GPS . and then drops at 390m if I stay at the same altitude over 30 mins, without pressure changes - still 1021 hPa).
I also noticed that the leevation gain during my workout has doubled for the same route, I believe since abou a month or two. Usually it would be 100m elevation gain and now it’s to 200m.
As shown on the screenshot, there is a drop in the middle (from 551m to 417m, gray shaded curve) ; I took a break (auto pause on) and did not go high or down. I guess it’s the auto calibraiton with FusefdAlti that does its job after a few minutes ?
But why the fluctuation when I stay at home jus after re-calibrating ?

any idea about the reason for this stranfge beahvior ?

I am using the S9PP with FW 2.37.48

I checked the forum about this issue but could not find similar cases.
thanks
Florian

[flo7z]

@flo7z

some pictures to illustrate the issue i am having (the pressure is correct, I checked the local weather app)

the trend of pressure is overnight, so I slept in my bed, whs is the altitude doing these spikes ?

Issues I am observing with workout are:
Elevation gain is too high.
Ascent and descent do not match anymore, 20% difference instead of a few percent before the issue started.
For example, a trail run with 650 m ascend and 540 descent (it should match since it’s a loop) is corrected by Strava at 380m !

[flo7z]

@flo7z

I noticed that this issue started in early November.
I checked the D+ against Strava and there is a clear difference (between the Suunto App and Strava), starting just after my 2-years warranty runs out…

The issue is at the start of my activity, I have crazy values of altitude and then after 10 minutes it’s fine (see on picture attached, this is supposed to be flat). But this messes up the overall d+/d- calculation.

Any suggestion on how to solve this ?
I am going to contact support I guess.

[flo7z]

@flo7z interesting to notice that by starting a second running workound just after finishing one, the issue is not happening.
I am thinking it’s due to the FusedAlti that has still the proper altitude and the GPS signal was still active on my watch maybe ?

[sartoric]

fusedalti needs 10 minutes to calibrate if the altitude is off.
try to wait a while in the activity screen before starting it.

anyway it should be applied retroactively

[Mff73]

@sartoric
Yes, it is the strange thing here : Fusedalti should have corrected beginning of altitude.
It looks like a very old behaviour

[flo7z]

@sartoric my altimeter is always on and it’s going crazy even when I’m at home, doing nothing

[ademgassymov]

@flo7z
After you start moving in a running/trekking types of exercise auto mode of alti-baro starts to measure altitude with gps that’s why you start getting correct readings. If you stop or when you’re in time mode it switches to barometric altitude and there’re several factors which influence - sea level pressure reference, actual pressure and temperature. I noticed that in summer when there’s not much temperature difference readings are usually correct. But in winter in this mode altitude can change even when you pull the watch from under your down jacket sleeve and temperature on the sensor drops quickly.
Recently I had an issue when altimeter suddenly started rising up to 9000m while I was quickly descending from 3700 to 3400 after a 15 minutes stop.

[flo7z]

@ademgassymov
I noticed the same, depending if I have a glove or not it changes the altitude accuracy.
Same when I take a small break, the watch goes on auto pause and this changes the altitude even if I don’t move .

What is strange to me is that the altitude was fine during two years and now it starts to go crazy.

[flo7z]

@ademgassymov
I finally got a proper elevation gain on a trail run. I succeeded because I left my watch 10 minutes outside, about 5°C, before to start my run.
The temperature seems to influence the altitude calculation a lot.

[Mff73]

@flo7z
it should not.
Altitude is correlated to sensor temperature, ok, but ascent/descent shouldn’t be influenced.
You might be facing a sensor issue (dirty or faulty).