Dewpoint - different values. **solved**

[Lespius]

Hi,
I notice that the dewpoint displayed on Raw Sensor Data (5.5°) is not the same displayed on MinMAX Data (6.0°):




The correct value for Temp=11.2° and Hum=68% is 5.5°
This is a problem because templates like Weather34 have the wrong value through their API (6.0°).
You can check Brian's answer: viewtopic.php?f=56&t=14398&start=1140
Do you now what's wrong ?

Alain

[admin]

Images of your post is missing. No idea why values should differ and I am a bit skeptical that they really do.

[Lespius]

Ok, I will try to be more explicit.

On one hand you have this:
"Outdoor 5.9° 90% (dew 4.4°, ...)" --> here dewpoint = 4.4°

http://www.meteo-cugy.ch/template/imgs/Capture32.JPG

On the other hand you have the Outdoor Dewpoint sensor --> here dewpoint = 4.9°
"Outdoor dewpoint 4.9°"

http://www.meteo-cugy.ch/template/imgs/Capture33.JPG

So we have two different values for dewpoint: 4.4° and 4.9°
I have checked, with a temperature of 5.9° and a humidity of 90%, the correct value of the dewpoint is 4.4°
So the value of the sensor is wrong. I must say that I have even seen it higher than temperature, which is physically impossible

[admin]

The yellow color of "outdoor dewpoint" indicates that this logical sensor is manuall redirected to a certain physical temp sensor. Therefore, I am not suprised that values do not match. Can you please show your mapping page?

[Lespius]

No change here

http://www.meteo-cugy.ch/template/imgs/Capture36.JPG

[admin]

Hm, strange. Could you please provide me a remote login? Please send URL and PW to "info(at)smartbedded.com"
Might be an old calibration infos somewhere in the settings file. But hard to say without having access.

[Lespius]

Done.
I will be away for a week. So don't be surprised if I don't react.

[admin]

Root cause is that there has been a calibration of -0.5°C defined for "th0temp".
On the "Raw Data" tab the dewpoint gets calculated from calibrated "th0temp" sensor, while on "Min/Max" tab the dewpoint is taken based on the original "th0temp". When calibration should also apply to "th0dew" it needs to be defined separately for this sensor. I admit that calibrating a calculated dew point value seperately is not best practice, but as Meteobridge does see all sensor data as unconnected data items it has be that way.

I added a calibration of -0.5°C to "th0dew" as well and data looks fine again.

[Lespius]

Well done, thank you