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Re: Hydreon RG-11 results

Posted: Wed 04 Jul 2012 6:55 pm
by steve
It would be possible, yes, but for now I'm holding off doing any more with the RG-11 until it becomes clear whether or not it's actually going to work reliably with the COM port connection.

In the meanwhile, you could use Select-A-Graph and create the graph manually.

Re: Hydreon RG-11 results

Posted: Wed 04 Jul 2012 8:27 pm
by duke
steve wrote:In the meanwhile, you could use Select-A-Graph and create the graph manually.
Is it possible to upload that to a website on a regular basis or just use the screen shot of it?

Re: Hydreon RG-11 results

Posted: Thu 05 Jul 2012 7:26 am
by steve
You can add it as an extra file to be uploaded automatically, yes. But you have to create it manually.

Re: Hydreon RG-11 results

Posted: Sat 07 Jul 2012 8:02 am
by apenwith
Hi
Results of July week one
Week1.jpg
Regards
Alan

Re: Hydreon RG-11 results

Posted: Sat 07 Jul 2012 8:52 am
by duke
That does not look promising. Especially as the two RG11's still do not agree with each other. It does not even come close to the results from Hydreon I posted here.

Re: Hydreon RG-11 results

Posted: Sat 07 Jul 2012 9:30 am
by apenwith
I would not take too much notice of the earlier part of the week - things were still quite experimental then but I put what there was anyway. The manual site is about 10M from the Cumulus site and closer to ground level so there could be differences. The performance in heavy rain is worrying though.
Alan

Re: Hydreon RG-11 results

Posted: Sat 07 Jul 2012 9:58 am
by bruce45
hi
i dont think we should be dismissing the rg11 just yet after all it is only the first rain results with the mod.
as for comparing results with other stations this really can only be used as a guide as rainfall can be so localised.
the met office gauges are for rain rate per square metre/yard so unless we are setup to there spec (which is unlikely) the readings that we record has to be taken for that location not an area.
yes the rg11 dose seem to be under recording but the rain rates could have alot to do with it. light rain could stick to the cover before forming larger drops that can be recorded.larger drops could bounce off and not record correctly.
the tip bucket is good but after a sudden shower there can still be water in the bucket after it has stopped raining so the next rain that comes may only take one or two drops to cause the tip which is ok for overall rainfall but not accurate for rainfall rate.

so far we have had no rain since the testing was done.

bruce

Re: Hydreon RG-11 results

Posted: Sat 07 Jul 2012 10:32 am
by duke
as for comparing results with other stations this really can only be used as a guide as rainfall can be so localised.

I asked for that so our rain graph uploads would contain a line for TB and RG so we could compare the 2. Not to each others.

I am curious how accurate the RG's are compared to each other? I shall shortly have 2 on the same mount about a foot apart. Can I run 2 instances of Cumulus on my weather server to record data from both in TB mode?

Re: Hydreon RG-11 results

Posted: Sat 07 Jul 2012 10:37 am
by apenwith
HI
as rainfall can be so localised
The manual site has all the gauges within a 1M radius (RG11 and Manual Gauge only 40cm apart) so they should be comparable. I surmise that as raindrops accumulate into bigger drops they are spaced further apart and might miss the small diamater of the RG altogether. So the bigger the catchment area the better the result (Pro 1 Sq M standard). Oddly enough the ratio of my various readings is not that far away from the ratio of the catchment areas of the instruments for last night's heavy rain. The nearby Met Station (20Km) reported 38mm so my higher readings are probably reasonable.
Regards
Alan

Re: Hydreon RG-11 results

Posted: Sat 07 Jul 2012 10:43 am
by steve
duke wrote:Can I run 2 instances of Cumulus on my weather server to record data from both in TB mode?
Yes, but they would probably have to be on separate serial ports. The other issue is that Cumulus expects to be connected to a weather station, so you'd have to work out a way around that, possibly using the NoSensorCheck setting.

Re: Hydreon RG-11 results

Posted: Sat 07 Jul 2012 8:45 pm
by bruce45
ok some early results with light rain no wind and the rg11 set at 0.001 inch dip switch 1 on.

rg11 0.09 inches tip bucket 0.08 inches

the bucket could tip next time it rains.

Alan

had to do the watering in the greenhouse and was able to watch the drops over the dome. the area were the screws fix i dont think would record rain. there is a shield inside to look at only certain areas. when it drys up ill try dropping water from a pippet and see what happends.

i was 6 foot but down to 5'6" all the running around the house to the gauge :lol:

Steve

sorry about the question before.

note to self: engage brain before typing.

forgot about the multiplier

will see how things go over night.

bruce

Re: Hydreon RG-11 results

Posted: Sun 08 Jul 2012 8:27 am
by apenwith
Hi
Experiment:-
Using a plastic beaker with four pin holes in the base I measured 5mm of 'rain' using the manual gauge. I dripped this onto the RG and exactly 5mm of rain was recorded. So my conclucion is that a) standard sized drops improve the accuracy and b) it suggests that my surmise of bigger drops spaced further apart missing the target areas is likely. The next step will be to try a bigger catchment area and factor down the readings.
Regards
Alan

Re: Hydreon RG-11 results

Posted: Sun 08 Jul 2012 8:46 am
by bruce45
interesting results Alan.
there does seem to be only 4 areas that drops are detected. any drops above this would have to run down over these areas to be detected.

from my over night results the rg11 was recording about the same as the tip bucket but around 7am got 0.3 inches more so have reset the logs and see how it goes

Re: Hydreon RG-11 results

Posted: Sun 08 Jul 2012 9:01 am
by apenwith
Hi
As you say there might only be small areas (four ?) where the RG senses so working out an optimum catchment area would be a bit of a guess. I intend to make my funnel the same size as the manual gauge and use the manual reading to calibrate against.
Alan

Re: Hydreon RG-11 results

Posted: Sun 08 Jul 2012 9:12 am
by bruce45
sounds like a plan.

what about if there was a tube fitted around the dome (with slots at the base to let the water out) and then inside that was the flat base of your beacker with the pin holes over each area. then above that could be the collecting area of what ever size.