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Whole number readings on Pressure?

Discussion specific to Oregon Scientific weather stations
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g0wfs
Posts: 6
Joined: Sat 03 Oct 2009 1:16 pm
Weather Station: WMR200
Operating System: Windows XP SP3
Location: UK

Whole number readings on Pressure?

Post by g0wfs »

OK I have a simple query regarding a WMR200 and Cumulus :-)

Example scenario..

Pressure is dropping and is currently shown as 1030mb. It doesn't change on Cumulus screen until 1029 mb is reached. E.G. it is shown as 1030.0 mb, then leaps to 1029.0 mb. But, it is being reported as dropping by 0.3 mb an hour in the box below?

However, uploads to weather sites (like WOW) report the pressure with the digit which follows the decimal point included. So pressure gets reported as say 1029.7mb, then 1029.4 mb and so on.

So my query is simple..

If Cumulus knows about the more precise pressure when reading from the console, then why does it not report it on the cumulus software screen itself?

Using whole numbers also makes Cumulus own (pressure) graph look very blocky? In fact you can have a flat line for hours if pressure doesn't change much. Whereas looking at your own uploaded pressure data in graph format is just fine (when viewed via WOW etc). As the small variations in pressure will be shown, because they have been reported in the uploaded data which Cumulus dumped on them.

So the more precise readings seam to exist, but just don't appear to be used on (or by) Cumulus itself :-(
Nidge
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steve
Cumulus Author
Posts: 26701
Joined: Mon 02 Jun 2008 6:49 pm
Weather Station: None
Operating System: None
Location: Vienne, France
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Re: Whole number readings on Pressure?

Post by steve »

The station supplies pressure in whole numbers of mb.

The rate of change is calculated over a three hour period, and that figure is divided by three to make a convenient 'per hour' figure; so a 1 mb drop over three hours gives a rate of 0.3 mb/hr.

WU and WOW (and the other sites which use the same protocol) require pressure to be uploaded in 'inHg', so the conversion to inHg and back to mb introduces a rounding error.
Steve
g0wfs
Posts: 6
Joined: Sat 03 Oct 2009 1:16 pm
Weather Station: WMR200
Operating System: Windows XP SP3
Location: UK

Re: Whole number readings on Pressure?

Post by g0wfs »

Hi Steve,

Thanks for the reply..
steve wrote:The station supplies pressure in whole numbers of mb.
Yes I understand that part.
steve wrote:WU and WOW (and the other sites which use the same protocol) require pressure to be uploaded in 'inHg', so the conversion to inHg and back to mb introduces a rounding error.
Ah OK. So basically, that is the way it is then when using a WMR200. No work around.
Nidge
aussiewmr
Posts: 104
Joined: Wed 23 Sep 2009 8:27 am
Weather Station: Davis VP2+
Operating System: Windows 10 Pro 1903
Location: Brisbane Australia
Contact:

Re: Whole number readings on Pressure?

Post by aussiewmr »

Yep - that was my biggest gripe about the WMR200 - the fact the pressure was in 1mb resolution.
Pretty poor for a $600 ish piece of kit.
It eventually failed on me hence the new WS. (the rain gauge tx failed, UV unit lasted only 6 months and the outdoor sensor was intermittent - would lose signal).

Still maybe the quality is better 2 years down the track.

Phil
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