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grebleem / weewx-weatherlinkliveudp

Weewx Driver with UDP
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Corrected barometer readings #4

Closed uajqq closed 4 years ago

uajqq commented 4 years ago

After leaving my station running for a few minutes, I noted the pressure being reported to Davis WeatherLink Cloud was a few mbar off as compared to weewx. It looks like the pressure the Davis console is reporting (bar_sea_level) should properly map to barometer, not altimeter (even though, confusingly, it does say in the Davis docs that the WeatherLink Live console is using the altimeter method). Making this change causes my weewx data to match what is being reported to WeatherLink Cloud (and my nearby METAR station), so I assume it’s the correct setting.

grebleem commented 4 years ago

No, that is not correct. The confusing part is that on the Davis Cloud side the graph says 'Barometer', but actually it is the Pressure at Sea Level. You can confirm this by doing a http request to http://10.1.1.47/v1/current_conditions (where 10.1.1.47 is the ip of you'e wll. It will give you a JSON file with the current conditions. Like this

Screenshot 2020-07-07 at 08 10 01 Screenshot 2020-07-07 at 08 11 09

You can see that the Davis 'barometer' is just the bar sensor reading with elevation adjustment. (also in my comments, this is coming from the Davis Api site). The barometer requires a bit more info to determine, see this link: https://github.com/weewx/weewx/wiki/Barometer,-pressure,-and-altimeter

Also a METAR is only corrected for altitude. Are you sure the altitude you set in Wheather link live is correct? Also check the time of the METAR, it could be an hour old.

uajqq commented 4 years ago

The elevation/altitude is correct (verified with map and GPS) and the data are up to date within 15 minutes. I’m confused why setting the data to “altitude” would be causing this much of a shift. Setting it to “barometer” makes it align with every other data source, including every nearby Davis station; setting it to “altitude” makes it read consistently 4 mbar too high (a difference of over 100 feet!).

What am I missing? Is there a weewx setting that needs to be adjusted?

grebleem commented 4 years ago

Did you set the altitude in the weewx.conf?

On 7 Jul 2020, at 13:50, uajqq notifications@github.com wrote:

The elevation/altitude is correct (verified with map and GPS) and the data are up to date within 15 minutes. I’m confused why setting the data to “altitude” would be causing this much of a shift. Setting it to “barometer” makes it align with every other data source, including every nearby Davis station; setting it to “altitude” makes it read consistently 4 mbar too high (a difference of over 100 feet!).

What am I missing? Is there a weewx setting that needs to be adjusted?

— You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub https://github.com/grebleem/weewx-weatherlinkliveudp/pull/4#issuecomment-654802067, or unsubscribe https://github.com/notifications/unsubscribe-auth/ABZOS6IBAI46SWVT6PMROQLR2MDZZANCNFSM4OSKG5MA.

uajqq commented 4 years ago

Sure enough, I forgot to update weewx.conf from my old station to match the altitude of the WeatherLink Live device, not the sensor suite. Sending data to weewx altimeter is now reporting as expected and matches everything. Thank you!!

grebleem commented 4 years ago

No problem, glad I could help!

On 7 Jul 2020, at 14:33, uajqq notifications@github.com wrote:

Sure enough, I forgot to update weewx.conf from my old station to match the altitude of the WeatherLink Live device, not the sensor suite. Sending data to weewx altimeter is now reporting as expected and matches everything. Thank you!!

— You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub https://github.com/grebleem/weewx-weatherlinkliveudp/pull/4#issuecomment-654824191, or unsubscribe https://github.com/notifications/unsubscribe-auth/ABZOS6KGFMF3AFUYLJS6OWTR2MIYJANCNFSM4OSKG5MA.