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Dew Point on WM-918's

Posted: Fri 26 Nov 2010 4:54 am
by serowe
Steve - how does Cumulus obtain the Dew Point on the Oregon WM-918?

The spikes I reported before on humidity also affect the dew point with very regular DP readings of 145, 162 and thereabouts.

Are these reported by the station or calculated internally by Cumulus as the spikes can happen consistently (well within a range of 20) for a few minutes to an hour or by itself (surrounded by zero readings)?

Re: Dew Point on WM-918's

Posted: Fri 26 Nov 2010 8:49 am
by steve
serowe wrote:Are these reported by the station or calculated internally by Cumulus
It depends on what you have told Cumulus to do. If you've told it to calculate dew point, it does so, from the current temperature and humidity reading. Otherwise the reading is taken from the station.

Re: Dew Point on WM-918's

Posted: Fri 26 Nov 2010 9:01 am
by serowe
Is there a default setting for this in V1? (will check but this doesn't sound like something I would have changed in the setup)

Re: Dew Point on WM-918's

Posted: Fri 26 Nov 2010 9:03 am
by serowe
Hmmm just checked and haven't checked this option.

So - what does Cumulus do if it gets erroneous readings? (in this case recall I know I have a sensor that occasionally gives dud readings so what would your calculations do if it sees humidity in excess of 100 (which, obviously, is incorrect?)

Re: Dew Point on WM-918's

Posted: Fri 26 Nov 2010 9:13 am
by steve
If it read a humidity greater than 100 it would use 100 instead.

Re: Dew Point on WM-918's

Posted: Fri 26 Nov 2010 9:18 am
by serowe
OK that might help my spikes then.

Re: Dew Point on WM-918's

Posted: Fri 26 Nov 2010 9:54 am
by serowe
OK back to questins on this one.

The values used for drawing the graphs - when a graph is drawn (let's use the Temp and Hum graph) is the graph ever redrawn or is a oint once plotted fixed in stone? eg if I have an erroneous reading plotted and I fix the Nov10log.txt file to remove the reading in error, what happens to the graph data?

Re: Dew Point on WM-918's

Posted: Fri 26 Nov 2010 10:03 am
by steve
You'll have Cumulus stopped to edit the file, so the graph will be redrawn when you start it.

Re: Dew Point on WM-918's

Posted: Fri 26 Nov 2010 10:49 am
by serowe
Nah - just have to do the editing real quick :)

All sorted - at least now I know how it re-draws the graphs. Thanks