DMS Weather Project: Build Log

[benemorius]

I don’t think the solution to the rain sensor is in software this time. I think it’s due to wind gusts flexing the pole with enough acceleration to flip the rain bucket. If true, this would be electrically indistinguishable from legitimate rain and so can’t easily be resolved in software. I’ve released the code already in a previous post. I just haven’t posted it on github yet, but I’ll do that as soon as I get some time.

I believe we’re going to need a physical modification in order to fix the false rain issue. Either stiffen the pole, or add guy wires, or move the rain sensor lower on the pole, or something else. Basically, the top of the pole (where the rain sensor is) is whipping around violently enough to cause the rain bucket inside to move. Each time it moves far enough to trip its sensor is equivalent to ~0.3mm of rain filling and tipping the bucket, and the software is interpreting it as such.

[HankCowdog]

I allowed for the possibility of guy wirea in the design. We can also shorten the mast back down to 6’. That will reduce flex by about half.

We can add eyebolts to the corners of the base and the top of the mast, then use piano wire/picture frame wire with turnbuckles to tighten the guy wires and add rigidity to the mast.

[benemorius]

We can add eyebolts to the corners of the base and the top of the mast, then use piano wire/picture frame wire with turnbuckles to tighten the guy wires and add rigidity to the mast.

This seems like an adequate solution to me, just based on visual observation of the mast during common daytime wind conditions (15 km/h; 30 km/h gusts). I suspect we need fairly minimal stiffening, but this is of course not remotely empirical, and I’d enjoy seeing more considered input. I regret that I don’t have a video to post showing the mast motion, but anyone can go on the roof at any time to observe it.

Tonight I modified the sensor script to report rain in negative magnitude in order to prevent propagation to wunderground (negative values are considered invalid by weewx), and added a logfile on the pi at /root/rpiweather.log so we can still see whether and when the rain sensor is activating. Running cat /root/rpiweather.log | grep -v "\-0.000 mm" on the pi will print a timestamped line for each occasion where the rain sensor bucket tipped, including false positives due to mast motion. This can be used to verify whether rain is indeed being reported during clear skies.

[benemorius]

Delightfully, the negative rain still shows up in the charts at http://dallas.ms/weather even though it isn’t reaching wunderground. It does look to me like there’s a correlation between wind and false rain. The magic wind speed seems to be about 40 km/h gusts.

another:

[actionjackson]

Upcoming Meeting

When: Thursday, 3/9
Time: 7 p.m. - 9 p.m.
Where: Interactive Classroom

We will finish up with the documentation, how others get involved. We will also discuss updating the website.

@HankCowdog
@benemorius
@LisaSelk
@sciborg
@brianbterry
@Gimli

All others are welcomed.

[sciborg]

A pic of our fearless leader! @actionjackson

[actionjackson]

contacting wunderground to get our station back up. we will have to hold off on our documentation set up until then.

[actionjackson]

Took down the weather station. The box will be located in Science on the black shelf named Weather Station.

1. Raspberry PI 3
2. OurWeather Plus board
3. Temperature Sensors
4. Rain Sensor

So from what I’ve gathered the servers went down two days ago. Around this time our station stopped reporting data all together. You cant access our page going through the Weather link. Possibly a corrupt SD card?

I’ll be working on it the next couple of days I’ll be up here, all day Sunday if anyone wants to join in.

[actionjackson]

3-20-17 Update

Thanks @benemorius making a script to restart Weewx. He found that because the servers went down including our, virtual server, that prevented the pi from serving up data to our website and wunderground.

Thank you @wandrson for your suggestion of using a white box to house our electronics. @MrPink suggested that we try spray painting it white. We did and just by looking at today’s results it seems that we were able to be in range with other personal weather stations(pws) by about ±5 degrees.

[actionjackson]

3-26-17 Update
Ok I’ve updated our github and wiki project page with documentation of how to get involved. My part of the project is done.If anybody sees something in the documentation that needs updating or clarifying, please do so or notify this log. It’s expected that people read our build log, visit our wiki page and/or read weewx documentation for installation help.

Weather Station Wiki
DMS Weather Github
Weewx.com

Possible Projects:

1. Place the rain sensor in a secure place where the wind will not activate it.
2. Redesign the weather station website so it is useful to outside users. Web Developer for DMS Weather

[actionjackson]

Hey guys we have a Science Committee Meeting Monday, April 24, 7 p.m. - 8 p.m. Purple Classroom. Since we are being funded by Science we need a representative to inform the committee of what the project is and know the guidelines that will effect our funding. Afterwards please post what guidelines are required discussed at the meeting on this thread.

This can be a great way to start in on this project, you don’t have to be apart of this project to represent us, I can fill you in on all the details. If you’re interested PM me.

@HankCowdog
@David_Steele
@sciborg
@benemorius
@Gimli
@bscharff
@brianbterry

[actionjackson]

Reminder Science Committee Meeting this Monday, April 24, 7 p.m. - 8 p.m.

[LisaSelk]

Thanks for the reminder!
…AND all the work you’ve done to help make the weather station a reality! :dms:

[Cairenn_Day]

Ia there a link to check it out? Since
I am 20 miles away, it would be nice
to check it at times

[LisaSelk]

https://dallasmakerspace.org/weather

[Cairenn_Day]

Thanks, I will keep that tabbed

[mblatz]

Noticed that the “Current Weather Conditions” for DMS indicated it was about ~38C° (or about 100° American) around 4:00p.m. today. Was it really?

[Cairenn_Day]

Roof we have a problem, it wasn t that hot!

[benemorius]

No it was not. It was closer to 30 or 33. The wind has been much calmer this past week (by a factor of 3 or 4) and it seems likely that this can account for the artificially high temperature reading.

We would still do well to improve the enclosure I think. The existing one has been painted white to help reduce solar heating, but it was still not expected to work well during the summer months, if I recall correctly. I’d guess we need to make it even more reflective, and perhaps increase the ventilation too. Or perhaps an umbrella of sorts is the way to go.

[TBJK]

Well when you have an instrument on a roof, you are more likely to get radiant heat built up. Controls wise ins the past we would always mount a OAT sensor on the north face of the building as high as we could get it in the shade.