Sudden pressure value increase in CWOP after upgrading to build 4064

[suanlian]

Screenshot 2024-12-15 222420.png

After almost 24hr since upgrading to build 4064, I noticed that there is a sudden abnormal increase in pressure values of my feed to CWOP.

Screenshot 2024-12-15 222135.png

See here.

Screenshot 2024-12-15 224133.png

My max pressure doesn't exceed 1022hPa in the last 24hrs.

Anybody experience this?

[Ulric2]

How do the values compare to the actual atmospheric pressure? You can find a value for your atmospheric pressure on this site http://weatherobs.com/

Maybe your station just needs calibrating? If the power to the station has been interrupted by a change of batteries or unhooking a power supply, it's not unusual for the pressure sensor to need recalibration.

[SamiS]

Bit of a wild guess, but I wonder if it is related to this from changelog of b4063:

Code: Select all

 
 Adds calibration for Station pressure (and so also for Altimeter pressure)
Note: If you use the option for Cumulus to calculate sea level pressure, 
then this new station pressure calibration is the one that will applied to the SLP as well

https://github.com/cumulusmx/CumulusMX/ ... ANGELOG.md

[mcrossley]

Ah!

This reminded me I meant to create a discussion on this before I released v4.3.0. It didn't even make the change log. My bad.

Whilst updating the APRS/CWOP code I noticed that the upload protocol specification says you should send the Altimeter Pressure value, but MX was sending the Sea Level pressure value, I changed MX to send Altimeter pending a decision.

I meant to open a discussion about which was correct. The spec or Cumulus?

However my sieve like brain got distracted and I completely forgot about this.

[PaulMy]

Code: Select all

Whilst updating the APRS/CWOP code I noticed that the upload protocol specification says you should send the Altimeter Pressure value, but MX was sending the Sea Level pressure value, I changed MX to send Altimeter pending a decision.

In the past I had read that the Davis Vue console provides the Altimeter pressure as required by CWOP, but if I recall some very old comments by Steve that that was not provided in CU1. I don't recall any other discussion on CMX other than the changes Mark made some months ago on the Sea Level Pressure option.

I meant to open a discussion about which was correct. The spec or Cumulus?

I would think sending Altimeter pressure would be the correct to send.

I know there is a lot of posting on pressure and it is interesting when a new record is broken like mine a couple days ago at an alltime high of 1045.6 hPa. But for weather watching I had learned that it is not the actual pressure measurement but the trend of the pressure that is important for observation.

Enjoy,
Paul

[suanlian]

How do the values compare to the actual atmospheric pressure? You can find a value for your atmospheric pressure on this site http://weatherobs.com/

Maybe your station just needs calibrating? If the power to the station has been interrupted by a change of batteries or unhooking a power supply, it's not unusual for the pressure sensor to need recalibration.

What I mean to say is my manually calibrated Station SLP = Cumulus MX displayed values ≠ APRS/CWOP displayed values

[suanlian]

Whilst updating the APRS/CWOP code I noticed that the upload protocol specification says you should send the Altimeter Pressure value, but MX was sending the Sea Level pressure value, I changed MX to send Altimeter pending a decision.

Screenshot 2024-12-23 013800.png

Does this mean that Cumulus MX sends it's own calculated values to APRS/CWOP no matter what I select in the settings here?

[mcrossley]

Screenshot 2024-12-23 013800.png
Does this mean that Cumulus MX sends it's own calculated values to APRS/CWOP no matter what I select in the settings here?

It depends on the station, some send an Altimeter pressure, some only send sea level* and absolute (station). In the latter case the Altimeter pressure is calculated by Cumulus.

* and some like the Ecowitt family don't even send that, they send an altitude compenstated pressure.

[suanlian]

Screenshot 2024-12-23 013800.png
Does this mean that Cumulus MX sends it's own calculated values to APRS/CWOP no matter what I select in the settings here?

It depends on the station, some send an Altimeter pressure, some only send sea level* and absolute (station). In the latter case the Altimeter pressure is calculated by Cumulus.

* and some like the Ecowitt family don't even send that, they send an altitude compenstated pressure.

Well I'm using an Ambient Weather WS-2902D. While this issue doesn't appear to bother many people, I am concerned because (if my understanding is correct) APRS/CWOP data is used by many other weather services. My area doesn't have any other PWS around and the nearest Airport (publicly reporting weather data) is 60+km away. That airport doesn't even report weather data 24hrs, they operate only when there are flights, mostly during sunshine hours. So it is very difficult already to calculate (what I think is) the correct pressure value for may station as there are no other personal weather stations to compare it against, only one airport. An option to select the SLP value would be nice for me, I think, as my APRS/CWOP feed would be different from what I feed elsewhere, if that make sense

[qisdtech]

Just trying to clarify something. Was there a new toggle or option to change the pressure that CumulusMX sends to APRS/CWOP after 4064?
I found the one toggle in settings for Sea Level Pressure, but enabling that option still does not seem to change anything either on the dashboard or CWOP data. Issue I'm having is CWOP data is reading 1014mb and everywhere else, including on the VP2 console, 1018mb. The 1018mb is the correct value based on the surrounding weather stations for my area. Is there another setting I should adjust? I have confirmed my elevation in the console, in CMX and the CWOP site all match. Thanks for your time. I'm running CMS v. 4.3.3

[mcrossley]

At the moment no. But I think the point is CWOP and your console should not match (unless you live at sea level) - they use different pressure values.