[Watch] SSU : altitude changes with temperature

Mff73

@Dimitrios-Kanellopoulos
Will try as soon as my SSU come back from Finland

Mff73

Hi, Suunto receive my watch, let’s wait 7 days from now :), but UPS said that it has been delivered on monday, so repair delay is calculated from when Suunto decided to registered the delivery
No matter, i am quite happy with my old Ambit, it is so reliable, just old fashion, no bluetooth, charger is a pain to clip, buttons have some arthritis , no fusedalti, but descent/ascent is spot on, and no difference between start/end of move.
Wait and see.

Dimitrios Kanellopoulos

I am reading in anxiety in every notification I get from this post. Good morning pal.

Mff73

@Dimitrios-Kanellopoulos
My only anxiety is that Suunto techs find nothing wrong.
But I send them à link of my video where I show that altitude lost 10m on a few seconds, just putting fingers behind.
In Suunto techs I trust.

Please @Dimitrios-Kanellopoulos , do not put too stress on you regarding my or others issues

Dimitrios Kanellopoulos

@Mff73 have another user with same issue let’s see.

Mff73

Just receive my new toy. Some driving to do towards week-end location, some drinks with friends there, and I will be ready to test

Mff73

Hello,
No vidéo to share, none of my test managed to change à single meter of altitude : neither fingers, nor température (reasonnable).
My new precious is perfect, old one was defective.

77alex77

@Mff73 said in [Watch] SSU : altitude changes with temperature:

Hello,
No vidéo to share, none of my test managed to change à single meter of altitude : neither fingers, nor température (reasonnable).
My new precious is perfect, old one was defective.

Hello,

Glad to see that you have gotten a new watch. I would like to ask you something of you don’t mind : could you check carefully how the altitude changes with the OUTDOOR feature. Actually my Suunto 9 has a very strange behaviour with altitude.

When I do a move with starting point equals to ending point, ascent does not match exactly with descent, I get almost 20m of difference, it is not logical at all.

During my vacation, I lived at 350m and every day I went to the Mediterranean sea. The altitude provided by my Suunto 9 was about 350m at home (ok) and about 20m at sea (nok) instead of a value in between 0 and 5m. I did several times a manual/automatic calibration at sea but the issue remained : I left the sea with altitude at 5m (ok), once at home altitude was about 350m (ok) then the day after when I went to the sea the altitude was about 20m (nok).

I have contacted Suunto service to get their point of view.

Thanks

Dimitrios Kanellopoulos

This is normal behaviour.

The altitude calibration from the GPS is never correct near by sea level. I am now actually at sea level for 1 mont and most devices report GPS altitude of -7.

To obtain the altitude check also some phone app about what GPS reports.

When you run the watch uses a feature called fused alti that calibrates constantly the altitude according to GPS reference combined with the readings of the pressure sensor.
When you start a move at the first 10 mins it tries to calibrate the altitude of the starting point. Eg like auto calibrating it your self , but actuality happening while running.
Thus you can have a different end point.

Also keep in mind the pressure sensor can be offset by many factors that’s why fused alti is there. To “peek” also from another altitude source.

Regarding the different gains , the barometric pressure change can affect it, however , also the route can.
That is why Suunto count ascent , at a -+3m threshold.

That means that if you don’t climb 3m in some minutes and you only climb 2 then it does not count.

So for example of you were runninh stairs up, and you did 2 stairs of 1m each it will not count. But if you did 1step again after doing the steps it would. This exists there to reduce noise, eg even arm movement that passes 1m etc etc.

I hope it helps.

PS to test your sensor , try to rub behind the watch , eg increase temp and see if altitude changes. Or if you are at the sea place , wear the watch , leave it aside, wear it again and you should have always the same altitude. That’s is how I detect those so far.

77alex77

@Dimitrios-Kanellopoulos said in [Watch] SSU : altitude changes with temperature:

This is normal behaviour.

The altitude calibration from the GPS is never correct near by sea level. I am now actually at sea level for 1 mont and most devices report GPS altitude of -7.

To obtain the altitude check also some phone app about what GPS reports.

When you run the watch uses a feature called fused alti that calibrates constantly the altitude according to GPS reference combined with the readings of the pressure sensor.
When you start a move at the first 10 mins it tries to calibrate the altitude of the starting point. Eg like auto calibrating it your self , but actuality happening while running.
Thus you can have a different end point.

Also keep in mind the pressure sensor can be offset by many factors that’s why fused alti is there. To “peek” also from another altitude source.

Regarding the different gains , the barometric pressure change can affect it, however , also the route can.
That is why Suunto count ascent , at a -+3m threshold.

That means that if you don’t climb 3m in some minutes and you only climb 2 then it does not count.

So for example of you were runninh stairs up, and you did 2 stairs of 1m each it will not count. But if you did 1step again after doing the steps it would. This exists there to reduce noise, eg even arm movement that passes 1m etc etc.

I hope it helps.

PS to test your sensor , try to rub behind the watch , eg increase temp and see if altitude changes. Or if you are at the sea place , wear the watch , leave it aside, wear it again and you should have always the same altitude. That’s is how I detect those so far.

Hello and thank you for your explanation. I’m going to think about it.