Cumulus Support

Hi

Is it possible to implement the temperature spike removal for a Davis Station ?

Sometimes I've some undesired spikes that MX doesn't skip. It seems Cumulus wiki says that temperature spike removal is only concerning to Fine Offset stations:

https://cumuluswiki.org/a/Cumulus.ini#Spike_Removal

Thanks in advance

It's possible, but I'm a bit reluctant to do it. Generally the Davis sensor readings are reliable and we only see odd values when sensors are failing. There are a couple of reasons I'm reluctant. First it would mask failing sensors, second we already see a few people caught by setting inappropriate spike values and wonder why their data keeps flatlining.

Having said that if people really want it, then it can go on the to-do list.

If it's implemented at some point it would be interessing to have an alarm if spike removal triggers

mcrossley wrote: ↑Wed 13 May 2020 3:32 pm if people really want it, then it can go on the to-do list

Sometimes bad ideas are wanted, but you can decline.
You have a say as well because implemented bad ideas may lead to more support effort which in itself is an argument not to implement.

I understand your reluctancy mcrossley but i think by default the temperature spike removal is 999 (ºC) so nothing to be afraid of if you have a non-faulty sensor
The spike removal would be set only for those who want to skip these unwanted spikes and set it on purpose.

I have a homemade SHT75 sensor for the Davis and I am very happy with its readings (compared to a sht35 in the same Davis sunscreen attached to an orange pi pc) but not as well isolated as I wanted so in certain storms (those with wind) temperature on screen turns to dashes.

Yesterday it was the last time and surprisingly the console did not register the 1,2ºC that MX registered.

As you say if more people wants it would be an interesting option.

laulau wrote: ↑Wed 13 May 2020 4:26 pm If it's implemented at some point it would be interessing to have an alarm if spike removal triggers

Good idea

Out of interest, what sort of spikes are you seeing?

mcrossley wrote: ↑Wed 13 May 2020 6:27 pm Out of interest, what sort of spikes are you seeing?

I see humidity spikes of 5% when the air is moist (>90% generally), most often in the winter. They don't happen all the time - in a protracted damp spell I see them once or twice in a 24-hour period. Very recognisable pattern on the graphs - you get a gradual trend in RH then suddenly have a reading which is 5% higher, then the next data point is back to the original level. They cause a corresponding spike in dew point temperature.

mcrossley wrote: ↑Wed 13 May 2020 6:27 pm Out of interest, what sort of spikes are you seeing?

Yesterday during a storm the temperature went suddenly from 14,9°C to 1,2°C in MX graphs during two minutes and again went to 14,9°C. Humidity didn't have such a spike.

freddie wrote: ↑Wed 13 May 2020 7:53 pm I see humidity spikes of 5% when the air is moist (>90% generally), most often in the winter.

I do see similar, though not usually as much as 5%, I think it is down to Davis not using a proper membrane to protect the sensor, just that useless wire gauze. It's allowing droplets to form. I did think that I'd get one of the proper Goretex type shields that Sensirion sell for the sensor and see if it fixed it. I think it would also extend the life of the sensor by preventing contaminants from getting to it as well.

Atlas wrote: ↑Wed 13 May 2020 7:57 pm Yesterday during a storm the temperature went suddenly from 14,9°C to 1,2°C in MX graphs during two minutes and again went to 14,9°C. Humidity didn't have such a spike.

Don't forget that spike removal only works if the change is between consecutive readings, temperature is read every 10 - 12 seconds. With traditional Fine Offsets it is every 48 seconds.

mcrossley wrote: ↑Wed 13 May 2020 9:23 pm
I do see similar, though not usually as much as 5%, I think it is down to Davis not using a proper membrane to protect the sensor, just that useless wire gauze. It's allowing droplets to form. I did think that I'd get one of the proper Goretex type shields that Sensirion sell for the sensor and see if it fixed it. I think it would also extend the life of the sensor by preventing contaminants from getting to it as well.

Yes, I agree that Davis protection membrane is very deficient. I think it has a lot of volume and that interferes with response change of temperature and humidity. The SHT35 beside SHT75 has a SF2 filter cap and is much more sensitive to temp/hum changes. The SF2 filter cap has minimal air room with the sensor.
For SHT1X old series exists SF1.

SHT35 working here every 8 secs:

http://www.meteoarchena.es/sht35.php

mcrossley wrote: ↑Wed 13 May 2020 9:23 pm
Don't forget that spike removal only works if the change is between consecutive readings, temperature is read every 10 - 12 seconds. With traditional Fine Offsets it is every 48 seconds.

Got it, I'm aware of that.

Hi,
Where can i find informations about T/H connection to IIS ?
Thanks

laulau wrote: ↑Thu 14 May 2020 8:16 am Hi,
Where can i find informations about T/H connection to IIS ?
Thanks

Physical or protocol connection?

Physical rj12 on IIS or transmitter (i know wind and rain pinout)
The protocole connection are in VPtools

I knocked this up years ago, any help?

Many thanks
Perhaps you also have the equivalent for Sun and Uv ?