Barometric pressure difference
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If by cleaning the sensor the pressure difference improved from -33hPa to just -5hPa, it seems the problem was the dirt accumulated over the sensor, no? Moreover, a few hPa of difference isn’t a big problem I think - if it’s a constant deviation - since all the correlated values are derived by pressure differences, so the absolute value isn’t a big problem. My Race has a couple hPa of deviation from our very precise barometer we have in the lab.
The problem of overestimated total ascents and descents is an issue frequently reported, likely not related to defective sensors. -
Hello, finally after a few days of monitoring after the intensive cleaning of the sensor, it would seem that the values indicated by the latter have become compliant again.
I checked several times the difference between the watch and the barometer at home which serves as a reference, and this difference oscillates between -2hpa and +1hpa which is quite reasonable in terms of precision.
It was therefore a problem of cleanliness of the sensor.
It is therefore necessary not to hesitate to clean it intensely with soapy water, rub it with a soft bristle brush then rinse with clean water.
Last information, when the watch is immersed or wet during a shower, the altitude no longer varies as it was the case before cleaning. This can therefore be a good indicator of the need for cleaning.
I think the subject can be closed, knowing that the problem is resolved. Thank you all for your comments and contributions to this topic. -
@Chris_Dx I followed your procedure of cleaning with a soft brush after immersion and it worked for me as well. My barometer is accurate for the first time in 6+ months! It also does not drastically change altitude when wet. Thanks for being the one to try it first, I was a little hesitant to clean the sensor with a brush as I was not aware of how fragile the sensor was.
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@Stefano-M64
I am cleaning my SV sensor regularly, but now when weather is quite warm my Verical shows around + 5hPa against nearest professional Czech Meteorological Institute weather station which is 5 km from my home. Strange is that in winter when it was cold they displayed the same value as the station. My wife has Race and and she had the opposite problem. In winter Race was off by -4 hPa and now when is warm it is O.K. And at the same time, I don’t feel like they measure ascent and descent incorrectly. Temperature sensor in both watches look also O.K. -
@PetrMisek the point is simple, we cannot expect that the consumer baro sensor of our beloved watch can be precise and stable (that is, not drifting) as the professional ones. In our lab we have one good reference barometer that was paid about 4’000 euros (ten times the price of my Race), and there are for sure more expensive models. In any case, also professional barometers need to be tested and re-calibrated.
Nevertheless, all the metrics we need are computed by means of pressure differences, so the absolute value is not that important. -
@Stefano-M64 yes yes I know that, I wrote this just for fun, because it also depends a lot on the ambient air temperature
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@PetrMisek maybe there is also an option to calibrate the sensor, does anyone know? I think that for the S9B this option was somewhere in the service menu
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I think there is room for improvement in the way the watch calculates altitude and pressure . For instance leaving the watch idle for some days one can observe that the altitude changes while it shouldn’t be the case … I assume the watch misjudges the changes in barometric pressure as altitude variation despite the fact there is no movement .
In ambit 3peak times there was an option to define those changes as altitude or barometric or automatic …
Unfortunate in recent days this is not the case -
I work in metrology laboratory, so I tested all my watch
. I compared Garmin Fenix F7 and lately F7Pro with some Huawei and Amazfit. Garmin was the worst, but only one or two hPa. But that doesn’t matter at all, if there was an option to manually enter sea level pressure and altitude. And even without that, it works normally, the trend is important.
Now my Race shows almost spot on with the etalon, if I set the altitude to zero, because the etalon measures ambient pressure.I found the link:
https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-7-series/340572/f7-pressure-laboratory-compare-just-for-fun -
@Jan-Suchánek Nice tests! As a scientist I deeply appreciate the data over anecdotal reports.
