Weather Station Hardware > Hydreon RG-11 Optical Rain Gauge/Sensor

Rain junkie? Use an RG11 in 0.0001" or drop counting mode

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Elsewhere here several years ago I posted here about my experiments with an audio disdrometer or rain detector. It plugged into a computer mike or line input and ran on Radio SkyPipe, a chart recorder program.

Yesterday, as I killed a glass of 20 bits Chuck* in the Think Tank, watching rain fall on the water surface and on the weather equipment on the post at the fence corner, I got to thinking about the 3 rg11s there, and what I could do differently with them.

So, as a part of my learning Opto22, I reprogrammed 2 of the RG11s, one as a one-ten thousandth" tipping bucket emulator and one in drop counting mode.

If you are a rain fall junkie, and hundredth of an inch tips aren't fast enough, or if you want an indication of how hard it's raining between tips, try one of these modes out. If you connected the RG11 to a relay or beeper, you'd get an auditory feel for how fast it's raining.

I have them each configured as counter inputs on my Opto22 system. By the time it rains again, I hope to have some code written to reset the counters, say, every 10 seconds and then graph it.

I also have that Opto22 controller uploading directly to a MySQL database.

I was running the tipping bucket emulator in thousandths mode for a while. As noted elsewhere and by Hydreon themselves, it's not real accurate compared to a real tipping bucket, about 25% low...

Comparing the 2 modes running now, last night, over about 45 minutes, the 0.0001" emulator recorded .0214" and the drop counter 550 drops. In that time, the VP2 recorded 0.01" of rain.

Here's a little comparison data from this morning's rain here in SLO.

Davis VP2                           0.78"
RG11 0.0001" TB emulator      2505 clicks or 0.2505"
RG11 Drop counter                22,390 drops

Those are probably off a little simply because I just grabbed them at a single point in time. What I should really do is wait for a Davis tip and then read the other numbers. But, the RG11s are so sensitive, they just keep clicking up as I'm trying to read. I really shoud wait til the end of the storm for a decent comparison.

So how many drops equals .01?


--- Quote from: ocala on April 07, 2015, 06:36:50 PM ---So how many drops equals .01?

--- End quote ---

Lemme look at my notes...

For the end of the storm we had 0.80" per the VP2. Per the RG11, it recorded 22,788 drops.

22788/80 = 284.85 drops per 0.01"

I wanted to do some of my own correlation calcs regarding drops and tips and such. I called Hydreon to find out the active sensing area they considered the RG11 to have.

They don't know....

I guess I'll do some experimenting and see what I can figure out. It's certainly less than the full diameter of the clear dome.


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