Doubt about Suunto 9 Baro altimeter/barometer calibration

@Dimitrios-Kanellopoulos said in Doubt about Suunto 9 Baro altimeter/barometer calibration:

also your friends had the same? It can be also due to a storm that came too fast to be detected thus influencing the altitude.

Yes, I not tested in deep with their watches, but they comment me the same/similar differences on the altitude.

In general, lets leave aside the day with the bad weather, if you leave the watch at the table you should have the same altitude. (or wear it in house but no shower etc )

This mean that if I wait until a good weather arrive, the altitude go back to correct values from the -14 of today? Thanks, nice info to check.

Just as curious: what is the fridge test?
Do you need that I put on the fridge (lower area) or fridge freezer (upper)?
Thanks again!

Dimitrios Kanellopoulos

well let me set it like so :

In regards to weather:

When there is pressure change caused by good or bad weather the watch should record it as a pressure change. However, the watch only looks at the pressure. It has a pressure sensor. So there is threshold that defines if it’s altitude change or pressure change. 1hPA is ~6m (if I recall correct) so think about it a bit. If you see the pressure rarely changes more than 3hPA. Imagine that the storm alarm gets triggered if it drops 3-5hpa per I think 3 hours. So that means that if only in 3 hours you would have descented (in terms of alti) 24m or so it would trigger.

If the pressure changes faster than 1hpa or so it will assume you are moving vertically as well. Then the altitude will change. Can a weather change do this ? yes . not often.
Will it change back to the original? No most probably. Most rapid weather changes go over slowly and might not produce the same pressure drop as when they are approaching or might be less impact-full (leave a pressure permanent change)

Fridge will do . Leave it there to drop from eg 25c on you to ~10-0c and check that the temp changed and tell me the altitude diff after .

@Dimitrios-Kanellopoulos said in Doubt about Suunto 9 Baro altimeter/barometer calibration:

When there is pressure change caused by good or bad weather the watch should record it as a pressure change. However, the watch only looks at the pressure. It has a pressure sensor.

Thanks for your complete explanation! I understand this, but the watch not get the parameters of alti-baro profile from MS that when sense a pressure variations assign this to the weather and not to the altitude? Or I´m wrong and the watch do this only into a Sport Mode?

1hPA is ~6m (if I recall correct)

Near ~8m

Now I think that I get what you explain me. Sounds logic.
But the watch not have a method to compare this bigger differences with the GPS altitude to get a more precise altitude measurement? If not exist changes in the watch positions, mean that all this pressure difference is from the weather.

Fridge will do . Leave it there to drop from eg 25c on you to ~10-0c and check that the temp changed and tell me the altitude diff after .

Done, but the only that change was the temperature. I believe that is correct because we not change the pressure neither the altitude. Results:

1010hPa -14m 21ºc
After 20 minutes at fridge
1010hPa -14m 8ºc

Dimitrios Kanellopoulos

@flypg great results love the icons. Your sensor looks more than fine.

On time mode the watch does not use any fused alti stuff.

Those are used only during activity. When indoors using the gps would be a disaster.

Lets keep an eye on this.

Mff73

One little remark, is it me, or it there many more posts about altitude/ascent /fusedalti stuff these times?
Personnaly hiking today. Altitude spot on at home 550m. 4 hours hiking after 30min drive. Watch altitude at Summit was 100m under reality. OK.
Back home and altitude spot on again

Dimitrios Kanellopoulos

@Mff73 that doesnt make so sense does it?

Mff73

@Dimitrios-Kanellopoulos
Strange indeed.
My remark is more oriented on the fact that I read many posts here and in other forums, where people “complain” about this “altitude”.
Something behind or just more people doing ascent during summer .

johann.fuehrer

@Mff73 May I ask how you did drive? Bike, Train, Car? My assumption is, that when you go ie. by car, it is not recognized as movement and therefore the altimeter stays on the “home” level. I think this is how fused alti works. Could it be that there are really 100m altitude difference between “home” and end of drive and vice versa?

Mff73

@johann-fuehrer
Thanks for answering.
I made a mistake
Altitude ok at home before and after activity in watch mode.
Ride by car from 550m to 1610m (real) without recording, so watch in “auto” mode . Not checked the altitude at start
Then hike from 1610 to 2110 real (summit) and here is Altitude vs GPS altitude.
Conclusion : no fusedalti in my hiking activity.
Btw, alti at home is OK before and after.

johann.fuehrer

@Mff73 I think to solve this we would need to know the trigger for an altitude change when in watch mode - so when the watch assumes you are moving or static. Maybe some wrist movements triggers this from time to time. That would explain, why the difference is “only” 100m and not the full 1000m difference from “home” to hiking start point.

freeheeler

@johann-fuehrer
I know I’m a bit offtopic since I am an old fashioned Ambit guy, but it seems to be a topic about fused alti, too?!

On Friday I went on a biketour (the one that we had to dig out our phones and maps for since we could not create a new route in MC and could not sync SA to Ambit…) and while we were in the gondola to get to the start of our tour (yes, sometimes I skip the pedalling part ) I did the calibration manually as automatic calibration with fused alti always takes ages…
In SA, I noticed later that the total ascent and the maximum altitude must be wrong. Also the altitude profile is not really what it looks like on the map…
The orange dot was at the actual highest point which is on the map at about 1’600m.

johann.fuehrer

@TELE-HO You are sure your baro is ok? It looks like it could not keep up with a “quick” altitude change when going up (and also when going down). If your baro holes are blocked (partially) it might be that the higher pressure from the base that you had in your watch, could not get out through this holes quick enough and therefore showing a wrong altitude (too low). But it seems that later this gets better. But strange in any way…

johann.fuehrer

@TELE-HO would be interesting to see the change compared to a real altitude graph…

freeheeler

@johann-fuehrer
yes, almost new watch and I am aware of the baro holes issue from my earlier Suunto Core…
The activities before and after were recorded without any issue, like I am used to.
I am pretty sure I confused fused alti with manual setting while “climbing” in the gondola and then immediately starting the activity.

freeheeler

@TELE-HO
this is roughly the graph of the route when I draw it in MC map.

mario_b

@TELE-HO AFAIK if you manually calibrate the altitude while recording an activity, fused-alti will be disabled. not if you calibrate it before an activity. would be nice to see this activity in MC because allways when fused-alti calibrates the altitude for more then around 8 meters, you see the pressure change in the baro diagram.

johann.fuehrer

@TELE-HO Is it possible for you to merge this one and the recorded one in to one graph? Maybe quantified.io is helpful? I did nor use it yet, but have seen a lot of such stuff is done in there by others…

Dimitrios Kanellopoulos

@johann-fuehrer Jup that is possible

freeheeler

@mario_b
yes I am aware that you switch off fused alti when manual calibrating during an activity recording.
Here’s the sea level pressure with the altitude profile.

@Dimitrios-Kanellopoulos
I don’t know who to do an overlay… but if I do an overlay, it would be necessary to have it almost idential from the drawn to the recorded track to have the best comparison, right?

Dimitrios Kanellopoulos

@TELE-HO update 2 activiteis / routes to QS.
Select them on the table
Press merge
Use the distance axis when viewing