Altitude and barometer issues.

tomviv

Before I send my S9 baro for repair I thought I’d post here to see if anyone could offer any advice. The problem is that the watch no longer seems to display the correct altitude during an activity and the barometric pressure is generally incorrect.
Before an activity I set the altitude to the correct height and by the end of a run I am supposedly below sea level, see the screenshots. This week I have been at sea level whilst I have been recording the runs with little altitude gain or loss. I have done both soft and hard reset and cleaned the sensor.
The barometer is always at least 9hPa out.
If I set the altitude to auto adjust, it eventually gets the correct altitude, so it seems the problem is only during an activity.

isazi

Avoid manually setting altitude just before an activity if you want Fusedalti to work.

tomviv

@isazi Thank you, I have tried this and the altitude is better. However, the barometer is still way out. Any suggestions?

sartoric

@tomviv said in Altitude and barometer issues.:

However, the barometer is still way out.

What do you mean for “way out” ?

tomviv

@sartoric around 8-9 hPa

ist-1973

@tomviv said in Altitude and barometer issues.:

around 8-9 hPa

If the altitude is set according to Google Earth Pro, then my barometer shows 10 - 11 hPa less than the actual pressure above sea level

Brad_Olwin

@tomviv @ist-1973 How do you know what the actual pressure is? This will vary depending on location and weather. I do not have a commercial weather site close to me so I cannot know exactly what the pressure is. My altitude will change when we have weather events. When I start an exercise FusedAlti will correct the altitude. I rarely adjust my altitude manually. The best way to do this is use the auto adjust, this requires the watch gets a good gps fix.

freeheeler

@tomviv
in addition to @Brad_Olwin 's comment, I’d like to add that you might want to read pressure as a relative value only, not as an absolute

surfboomerang

@tomviv I live at sea level and just checked my S9P.

Watch: Alt 0m, Baro 1021hPa
3 Offical weather stations around me within 30km: 1019.1 - 1019.3 hPa

Well within margins I would say and, as @freeheeler already mentioned, the speed in which pressure raises or drops is more important than the exact value.

sartoric

As an additional note, the baro sensors in our watches cannot be compared to a precision one used in most professional weather station, so there can be some discrepancies.

If you search the forum there is an old topic about pressure,sensors and precision

ist-1973

@sartoric The height is the same. The pressure is different.
Which clock shows correctly?

freeheeler

@ist-1973
that’s impossible to tell IMHO… what’s strange is that baro graph isn’t the same. did both watches stay together the past 12 hours?

sartoric

@freeheeler said in Altitude and barometer issues.:

did both watches stay together the past 12 hours?

And both should be in the same conditions, clean, not covered etc.

ist-1973

@sartoric Yes. Together.

ist-1973

@ist-1973 On the clock scale, the division price is different. 2 hPa, and 4 hPa

ist-1973

@ist-1973 The conditions are the same. Together on a closet shelf.

freeheeler

@ist-1973
strange… maybe you need to clean the sensor (soak it in water) and observe again

ist-1973

@freeheeler
Today I went for a run with my wife along the same route. Here is the data.
Difference in watch pressure 9 hPa![1659269024817.jpg]
(/assets/uploads/files/1659269649255-1659269024817.jpg) ![1659269024829.jpg]! (/assets/uploads/files/1659269685098-111.jpg)

freeheeler

@ist-1973
looks alright
I assume you can ignore the pressure difference as everything else looks good

tomviv

@freeheeler thank you. I think this is where I was going wrong although I’m assuming absolute pressure is at sea level, which is where I was for the week. Now I am back at home it makes more sense for the readings to be out by 8-9 hPa given my altitude.