Sandaysoft

I've been using Oregon Scientific (WMR-968) for near some four years now. One of the characteristics or quirk is the temperature gauge in that at -10 degrees celcius (14 degrees fahrenheit), the humidity sensor locks down at whatever it was showing and remains that way until the temperature rises about -10 degrees celcius.

In order to get around that problem, which will cause bad quality checks with CWOP, I use the "cold-climate" sensor (THGN123N) and of course have to use it as an "extra sensor" or designate it my main temp/hum sensor. This particular year (and I am still watching it), it appears that it may not be all what it was claimed to be, as I had some nights that the temperatures were in the zero mark and it appears that this sensor may be locking down or not functioning in correct humidity reporting below the -10 celcius mark.

In light of that quirk of what seems to be a quirk of the Oregon Scientific only, I would like to see the option of manually shutting off the humidity reporting during that period of time when the temperatures are in that range, which would facilitate not receiving poor QC checks from CWOP - often times I will see some nearby stations in CWOP not reporting humidity and the available data such as temperature, wind speeds etc., is still accepted. Course the dewpoint data is also vacant as it cannot be calculated without the humidity data.

I do believe the option of extra sensors would enhance the overall experience with Cumulus, whether it be an option and accessible via the control panel configuration or manually altering the configuration initiation file.

Also, having the capability of designating one of those extra sensors as the "main" sensor would facilitate a faulty sensor. Currently I have a malfunctioning main temp/humidity sensor, which I have not replaced yet.

I did start to look into displaying extra sensor data from the Oregon stations, it's really a question of where to display the data, in the current version. There are the three slots that the Davis stations use, something could be put in there. If I found the time to do it.

Steve

I'm having the same problem. In fact, I suspected that the sensor unit was malfunctioning and bought a new temp / hydro unit. Same result - the humidity locks in once the temperature gets below a certain value.

This is indeed frustrating!

Has anyone reported this to Oregon?

I sent a technical request into Oregon today (1/1/2009). I'll let you know when I get a reply.

If this is indeed a known design problem with these sensors, it's reasonable that I add an option to cater for it.

Steve

I have not heard anything from Oregon Scientific technical support.

So far, we have seen this identical behavior with 3 of their temp/humidity units - so I think we can say that this is confirmed.

I suggest that you turn off the humidity reporting when the temperature is less than 15 deg. F.

I took one of my temp/humidity units apart. It has a small circuit board inside with both the temperature and humidity sensors. It appears that the humidity sensor is a resistive type - this requires a big temperature correction. This is why the temp and humidity sensors are found together. There is an integrated circuit in the middle of the board - but it is covered over with a big blob of black epoxy. I was hoping to find a number on the IC to determine what it does.

I think when the temperature falls below 15 deg. F, this is outside the humidity temperature correction range and the board just maintains the last good reading.

Unfortunately, the design of Cumulus precludes "turning off" reporting a particular item. When it receives 'bad' data, or no data at all, like these sensors it continues to report the last good value it had. It has no concept of a 'null' value.

However, if you're just talking about not reporting the value to APRS, I can do that

Steve

Steve -

I have examined some APRS/CWOP reporting stations data and we do have some not reporting humidity, so I don't believe that would be out of line to have that option that could be selected when this particular Oregon Scientific temperature condition occurs. I know that turning off the humidity, while its not complete data for a period of time, does eliminate one receiving bad QC reports because of the dew point discrepancy.

In light of what was said above, it's interesting that Oregon Scientific makes no reference to the humidity problem in their description or operating manual and I am quite sure they've been aware of it - I went through that manual several times with a fine tooth comb thinking I missed something, but alas is not there. My overall opinion on the "cold climate" sensor is still not totally conclusive - sometimes I think its' humidity operates below -10 celcius and sometimes it looks like it doesn't.

Don

I've added this to the latest beta:

http://www.nybbles.co.uk/downloads/beta185/CumulusSetup.exe

It doesn't report humidity to APRS when the temperature is below -10C. To enable, add

APRSHumidityCutoff=1

to the [APRS] section in cumulus.ini before starting.

Steve

This option is works well and definitely enhances the use for those of us that have the OS stations.

OK - thanks for the feedback.

Steve