I think I understand what you are asking.
By default, the Fine Offset driver reports only absolute pressure. WeeWX
uses this, as well as altitude and temperature, to calculate "altimeter"
and "barometer". Relative pressure is not emitted by the driver at all.
If for some reason you really want "relative pressure", here's what you
would need to do.
1. Figure out the relative pressure offset used by your console. From your
description, it sounds like it is 1011 - 950 mbar, or *+61 mbar*.
2. Figure out what unit system you are using. This is under section
[StdConvert] in weewx.conf. Unless you changed the default, this will
be "*target_unit
= US*".
3. Convert the offset you got in step #1 to this unit system. For
example, +61 mbar is *+1.801* inHg in the US system.
4. Use this number for a new [StdCalibrate] expression in weewx.conf. For
example, enter this in your weewx.conf:
[StdCalibrate]
[[Corrections]]
*rel_pressure = pressure + 1.801*
Restart weewx.
Now you will have relative pressure as observation type "rel_pressure". You
can then use this in your template as $current.rel_pressure. If you want
historical relative pressure as well, you will have to add rel_pressure to
your database schema.
But, frankly, I don't know why you would want to do this. The Fine Offset
"relative pressure" is a poor substitute for altimeter and sea-level
pressure.
-tk
On Sun, Sep 22, 2019 at 6:25 AM Miguel Ángel <[email protected]> wrote:
> Thanks for your reply Thomas, I had read this article and that's why I
> changed the names of sensors to try something. With relative pressure I
> want to say the absolute pressure plus an offset. (for example, the
> absolute pressure show 950hPa, and the relative pressure show 1011hPa, both
> in the station, but weewx only show 950hPa.) Actually I am not an expert in
> this topics, but I've always seen the pressure on these figures
> (1000-1020hPa), and now I get lost (with 940-960hPa).
>
> Miguel.
>
> El domingo, 22 de septiembre de 2019, 14:53:42 (UTC+2), Thomas Keffer
> escribió:
>>
>> Take a look at the Wiki article *Barometer, pressure, and altimeter
>> <https://github.com/weewx/weewx/wiki/Barometer,-pressure,-and-altimeter>*,
>> and see if that answers your question. If not, perhaps you can tell us what
>> you mean by "relative pressure."
>>
>> -t
>>
>> On Sun, Sep 22, 2019 at 5:43 AM Miguel Ángel <[email protected]> wrote:
>>
>>> Hi, I have recently installed WeeWX v3.9.2 in my Raspberry Pi 2, with
>>> the PCE-FWS 20. All is working, but this station has Absolute and Relative
>>> pressure, and in the section Barometer, WeeWX show me the Absolute pressure
>>> and I want to see the Relative pressure.
>>> I have tried changing names of sensors in index.html, but doesnt work,
>>> and I dont know how to change the source of the barometer. I use NeoWX, as
>>> skin (Standar show absolute pressure too).
>>>
>>> Miguel.
>>>
>>> --
>>> You received this message because you are subscribed to the Google
>>> Groups "weewx-user" group.
>>> To unsubscribe from this group and stop receiving emails from it, send
>>> an email to [email protected].
>>> To view this discussion on the web visit
>>> https://groups.google.com/d/msgid/weewx-user/d30f205c-8e1c-4011-82c2-2d279ab753f2%40googlegroups.com
>>> <https://groups.google.com/d/msgid/weewx-user/d30f205c-8e1c-4011-82c2-2d279ab753f2%40googlegroups.com?utm_medium=email&utm_source=footer>
>>> .
>>>
>> --
> You received this message because you are subscribed to the Google Groups
> "weewx-user" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to [email protected].
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/weewx-user/dcfdc929-53ef-43d4-9eb3-132a0a68974b%40googlegroups.com
> <https://groups.google.com/d/msgid/weewx-user/dcfdc929-53ef-43d4-9eb3-132a0a68974b%40googlegroups.com?utm_medium=email&utm_source=footer>
> .
>
--
You received this message because you are subscribed to the Google Groups
"weewx-user" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To view this discussion on the web visit
https://groups.google.com/d/msgid/weewx-user/CAPq0zEAtOEqkrL8o5MSh2KCxTpvg0h0jwM7TNtSzzXKAFhY4Wg%40mail.gmail.com.
