I found that additional information
at
https://www.manula.com/manuals/pws/davis-kb/1/en/topic/barometric-pressure-issues.
There they say, that Davis uses different calculations in different devices:
- VP2 and envoy consoles: sea-level pressure ("barometer", QFF)
- WeatherLinkLive: altimeter pressure ("altimeter", QNH)
- Vue consoles: user can choose between the two
So it seems, the author of the "weatherlinkliveudp" driver read the
documentation most carefully.
And to confuse the user or something, in the LOOP data record, Davis calls
the value, what we learnt is altimeter, "bar_sea_level".
The archive record contains all the three values barometer, altimeter, and
pressure (I checked). Since the "weatherlinkliveudp" driver does not
provide a value for barometer, may be, WeeWX calculates it by itself.
didier....@gmail.com schrieb am Samstag, 21. November 2020 um 20:54:45
UTC+1:
> Thank's a lot
> I'm learning a lot of things with you
>
> Le sam. 21 nov. 2020 à 18:59, vince <vince...@gmail.com> a écrit :
>
>> On Saturday, November 21, 2020 at 9:31:11 AM UTC-8 kk44...@gmail.com
>> wrote:
>>
>>> didier....@gmail.com schrieb am Samstag, 21. November 2020 um 16:09:22
>>> UTC+1:
>>>
>>>> Ooops, after 10 mn the 2 values have diverged (only 1 mbar)
>>>> The explanation is that weatherlinkliveudp driver uses "altimeter" and
>>>> WLLDriver uses "barometer" for the station info
>>>>
>>>
>>> That I do not understand. Does the driver only retrieves the readings
>>> from the hardware, doesn't it? So, which way the driver can influence which
>>> values is displayed?
>>>
>>>
>>
>> There are two pressure-related elements provided by the Davis hardware.
>> One is the pressure as reported by the sensor, the other is the pressure
>> corrected to sea-level pressure based on your altitude. The driver code
>> defines which sensor values it uses for what generic weewx database element
>>
>> Both drivers map 'bar_absolute' from the hardware to weewx 'pressure' in
>> the database.
>>
>> But...the two drivers map 'bar_sea_level' from the hardware to different
>> elements in weewx's database.
>>
>> - WLLDriver.py puts the value into 'barometer' in weewx
>> - weatherlinkliveudp.py puts the value into 'altimeter' in weewx
>>
>> According to
>> https://github.com/weewx/weewx/wiki/Barometer,-pressure,-and-altimeter,
>> the correction math differs slightly, so I'd expect slight differences
>> perhaps. A difference of 1 mbar to me isn't something to worry too much.
>> You're talking 0.1 percent offset. The sensor itself isn't that precise to
>> begin with.
>>
>>
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>
>
> --
> Quel temps fait-il à Auffargis <https://meteo-auffargis.decoodt.eu> ?
>
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