Doubt about Suunto 9 Baro altimeter/barometer calibration

mario_b

i was confused before too. i think that the S9 also like the Ambit3 is not showing ambient pressure, but showing sea level pressure calculated with QNH. that calculates the from the ambient pressure and Altitude the sea level pressure without taking care of the temperature. the temperature is always calculated with 15° celsius. like METAR (METeorological Aerodrome Report) so for all the airplanes. local weather stations taking care of the surrounding temperature which gives you completly different values. search for your nearest Airport and METAR in google. for example METAR vienna and stay on the same elevation. you should get a quite accurate reading.
using QNH calculations gives you a great way traveling to a destination and set your watch to a pressure anywhere in the world, if you took that QNH value for getting nearly accurate altitude values.

@dombo Yes, exactly. Later I noted this thanks to the Suunto Support. Thanks.
@mario_b Exactly, METAR is a great reference around the world and with useful information.

I pasted here the explanation/information in case that be useful for some other.

The watch shows:

altitude
sea level pressure

It will not show the absolute pressure. These values are interdependent - when you set one, the other one is changed so to be compatible with the absolute pressure the watch is measuring.

An example of this is set altitude to 0, you would see a sea level pressure equal to the absolute pressure - 1016 hPA. Setting altitude to 38 meters, the watch would know that absolute air pressure is 1016 hPA and infer that sea level pressure is higher - 1021 hPA.

Absolute air pressure is measured constantly (though not displayed): Absolute air pressure + altitude reference = Sea level air pressure

Absolute air pressure + sea level air pressure reference = Altitude

Changes in local weather conditions will affect altitude readings. If local weather changes often, it is advisable to reset the current altitude reference value frequently, preferably before starting your journey when the reference values are available.

Mff73

Hey guys, nice discussions, but hope you are not confusing SA setting for Altitude source, and watch ?
The only settings currently in SA, is to choose if your smarphone will determine altitude with GPS or Baro, if you intend to record an activity with SA and your smartphone (not your watch).
The settings for watch activities altitude source are still not changeable in SA, still only in MC for now.
Does it make senses ?

DavorP

@Mff73 Can you access altitude source settings for Spartan Ultra. This is screenshot of my settings in SA 4.2.4. (SSU)

Mff73

@DavorP
Sorry but you are confusing, i will try to explain.

SuuntoApp is SA, it is an app on your smartphone, your phone have a GPS, and the app could record activities with phone GPS data. This setting in the App is to determine if the Altitude come from GPS or Baro, only for the app recordings.

Your watch, SSU, but for all others users, can also record activities on its own, have settings and these settings are not managable currently via SuuntoApp. They are still managed in Movescount on the web.

Activities from the watch are synced to SA, but both kind of recordings (and thus alti settings) are different.

Does it make sense ?

DavorP

@Mff73 Now I see, thanks for clarifying…

@Mff73 Thanks, now I feel like an idiot! jajajajajaa

Looks that this mean that the watch started to display correct informations after altitude calibration (auto-adjust).

Personally I don’t use the SA to record activities. For me is not sense because for this I have my watch, but maybe for other users is useful. I always imagined that this settings was for the watch, like when I did from MC. Maybe they need add some sentence into the SA on this setting to clarify this or I’m be the main idiot that not understood this

The settings for watch activities altitude source are still not changeable in SA, still only in MC for now.

I hope that soon is added on SA for each Sport Mode and for the overall watch. Because I moved to use SA and can’t control this now

mario_b

Personally I don’t use the SA to record activities. For me is not sense because for this I have my watch, but maybe for other users is useful.

@flypg i would not underestimate that feature. 3 reasons for that.
-when you forgot your watch or forgot to charge it or on vacation you forgot your charging cable (like I did)
-when your watch (hopefully not) has to go to a service
-or when your in training and just wanna record your effort. (PTE, EPOC, recovery time) i use that when I am bouldering or training at the climbing gym. I don’t take my watch or phone with me. I but on the smart belt start the activity on the phone and lock everything in in the dressing room. (I would destroy the watch while bouldering for sure)

@mario_b Nice tips, I mainly use my watch to not use any other instrument or device during activities. Until now I could cover this objetive.
Is good share different focus or usage of each one of the same product because we learn from other perspectives. Thanks!

Mff73

@flypg said in Doubt about Suunto 9 Baro altimeter/barometer calibration:

@Mff73 Thanks, now I feel like an idiot! jajajajajaa

This setting could confuse when thinking the app is 100% watch related.
Agree that Suunto should add some tip on this.

And to conclude, Idiots don’t know they are idiots, so if you feel idiot, you are probably not .

Hello everyone, I kept watching this, and after see that other users with Suunto 9 have problem with their altimeters, I did more tests. I really don´t know if this is a problem or is a normal behavior of the firmware. I can´t understand for what the Suunto 9 Baro displays me frequently wrong altimeter data. The sensor is clean and works perfect, I runned tests and take perfectly the altimeter and pressure variations, etc.
After a correct calibration that my S9B display me a correct value of altimeter and pressure, if I mantain in the same area and the weather goes wrong, the pressure goes down (OK) and the altimeter drop the value that displays.
For example, from a nice day of high pressure in a correct altimeter data of around 35mts, on the same place after 3 days, but with bad weather, the S9B displays me a drop on the pressure (OK) and a altimeter data of -14m… (minus-negative) ¿?
I really don´t understand this behavior. This never happen to me with the A3P.
What mean? That on S9B I need re-calibrate each day?
Also I received a Storm Alarm on a beautiful sunny day and today that we have storm with hail, nothing. I can understand this, maybe the drop of the pressure on sunny day was more violent than today, OK, but the changes on the altimeter not sounds logic.
Can be possible that something is wrong on the firmware of the S9B?
@Dimitrios-Kanellopoulos I add you in case that you miss this because I see that you have more similar reports about the altimeter. Thanks to everyone.

Dimitrios Kanellopoulos

@flypg I suspect it needs cleaning / service.
All the above show from my experience this behavour.
Do me a favor and put the watch in the fridge for 10mins. Will the altitude rise ? (and the temp of coursE)

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

I suspect it needs cleaning / service.

Thanks!!!
This for me is strange, because I see this behavior since new. Also I tested the same behavior in other S9B and S9B Titanium from friends :S It would be a lot of coincidence.

All the above show from my experience this behavour.
Do me a favor and put the watch in the fridge for 10mins. Will the altitude rise ? (and the temp of coursE)

@Dimitrios-Kanellopoulos OK, I do on the afternoon: fridge or fridge freezer?
Thanks again!

Dimitrios Kanellopoulos

@flypg 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.

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 )

@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?