Adjustment for humidity values

[janegils]

I can see that when you click on 'edit' for a temp/humidity sensor you can enter an adjustment for the temperature readings.
But there seems to be not possible to enter adjustments for the humidity value, which would be even more useful since humidity sensors tend to be rather inaccurate.
A precision of +/-5% is fairly common.
As an example: I have two Esic temp/hum. sensors on my table now, and the temp. readings are identical, but the humidity values have a 9% difference.

Would others like to see this implemented?

[elythomaslumber]

9% is a big difference; but is the difference linear meaning always 9%?
Makes only sense to have an offset if the difference is always the same.

Regards

Hardy

[janegils]

Well, with som testing one can find the average offset, and at least get closer to the truth...

[marin849]

There are usually both an ofset and a scaling error!

I have just compared 15 sensors against each other. Tested sensors are the quite common Proove TSS320,Viking 02812. Both are using the Viking 2035/2038 protocol. Also 4 Viking temperature only sensors.

All of them are within +-0,5C for temperatures between 0-20C, and with ofset correction this is reduced to +-0.2. With linear correction its perfect. Of course it should be calibrated over a bigger interval than I did.

The humidity varies more: +-5% uncorrected. This is a lot since it means that one sensor can show 65% and another 75% which could be critical when monitoring or controlling humidity for corrosion or mold growth. With ofset corretion it is about +-3% and with linear about +-1,2%. The middle humidity point does look strange, maybe I had to short settling time on that one...

So with these observations linear correction would be really nice, especially for humidity!

[ThinkPad]

I would also like to see this.
I have a Z-Wave sensor with combined temperature and humidity status, i can correct the temperature, but not the humidity (which is about 10% off from two other sensors).

[sharif]

Is this feature on the roadmap?

I got few sensors which are showing about 7% more humidity and I would like to adjust this value/offset.
Only thing I can adjust at the moment is temperature (as already stated)

[michib]

+1 for the correction feature for humidity values.

[kubrik]

+1

[mayyam]

+1

____
may

[StratosHF]

+1

[zhoblom]

Yeah, that would be a tremendously helpful feature. It's ironic that temperature sensors that are nowadays pretty accurate can be offset-calibrated, but humidity ones can not.

Interestingly, there is provision in the code to do that. There is already AddjValue and AddjMulti for temperature, but similar block for humidity (using AddjValue2 and AddjMulti2 columns from DeviceStatus table) is there, but disabled:

Code: Select all

/*
        AddjValue=0.0f;
        AddjMulti=1.0f;
        m_sql.GetAddjustment2(HwdID, ID.c_str(),Unit,devType,subType,AddjValue,AddjMulti);
        Humidity+=int(AddjValue);
        if (Humidity>100)
                Humidity=100;
        if (Humidity<0)
                Humidity=0;
*/

It seems to me that at least for experimentation purposes and for local builds uncommenting this block and then just populating correct AddjValue2 and AddjMulti2 for a specific device in the DeviceStatus table (using sqlite3 command line utility for example) will suffice.

Also note that DB schema allows for two-point calibration, not just one offset, as in the GUI. So with a few extra lines of code one can get even better results than just offsetting humidity by a fixed offset.

Of course, adding GUI support would be some extra work on top.

[pa3gmi]

Also would like this option.

[mpx2]

I think that setting two reference points like 11 % and 75 % with offsets is enough.

[video]https://www.youtube.com/watch?v=AGycwfeHH_k[/video]

[tvurce]

+1 for humidity offset

Specialy Bosh BME280 is popular, but crap... 25 % deviation no problem

[JanAtHome]

+1 for humidity offset

[sperate]

+2 for humidity offset

[GJKNL]

+1

[magoafono]

+1 for humidity offset!