I’ve made a bit more progress with the VP2 now. I’ve added the USB to serial adapter to the WD PC, loaded up WL and connected the console to the PC. I’ve also put the ISS outside (just sat on a wall for now further away than it will be when it’s mounted) and I’m getting a decent signal from it.
This is about as far as I can go without climbing ladders and drilling walls to mount it properly. I’m going to tray to get that done on Monday or Tuesday.
One final question…I’ve put my height ASL into the console. Does this mean that the console displays SLP rather than local pressure? WL and the console show the same value, but did I read somewhere than WD sees the raw local pressure rather than SLP? The pressure shown by my WMR928 is about 2mb lower than the VP2 and that’s the kind of difference I’d expect between SLP and my local pressure (I’m at around 20m ASL).
It will also depend on the construction of the sensor and sensor housing. The sensor may be 3D or if it is horizontal it may be mounted under a lens which focuses any sunlight at most angles onto the sensor. I’ve not seen the VP2 sensors, but the docs suggest they have diffusers which I assume are used to help get light at low angles to land on the sensor?
Yes, no lens, it has a horizontal diffuser, and they expose a little of the vertical edge to enhance the performance at very low angles where the light will be bouncing off the top surface. There’s a good write up on this type of design here http://www.for.gov.bc.ca/hfd/pubs/Docs/Wp/Wp53.pdf
You do. The straight line is effectively the inverse of cloud cover (although other things like pollution could also affect the reading). The maximum number changes throughout the day and if you sensor is receiving the maximum (or very near maximum) then the sky is clear.
I’m glad we all meant the same thing once we worked out what we were saying :lol:
Best of luck with your mounting Chris, nearly got blown off my ladder yesterday with a 30 mph+ gust
I’ve not used a UV sensor for insolation, but when doing UV emission spectroscopy our apparatus utilised quartz because glass is a bigger UV absorber.( Have never seen a VP UV detector, so have no idea about it’s structure. )
Whew! Thought I was really being dense. I’ve been on a 5 hour road trip and haven’t thought about anything else since my last post. Glad you guys were able to work it out. Thanks for the discussion.
–Dave
Derivatives can be tricky to get your head round…comparing a maximum expected value (following a curve) with a maximum measured value (following a curve) can give a straight line.
However, it looks like the VP solar sensors are designed to try to give a reasonably flat response for a large range of angles of incidence, so they’re really measuring atmospheric effects for most of the day.
I have the 1-wire from Hobby Boards and it appears to be very sensitive but the bell curve is pronounced due to the design of the sensor, I believe. (Not due to the Hobby Board’s board, BTW.) Can’t speak to the VP sensors. But… I clearly (pun intended) understand about the ‘reasonably flat response for a large range of angles of incidence’. I think my saying 100% is what caused all the discussion, because in practice it would never be 100% due to the atmoshpere or any other attenuation.
I don’t use it for anything important but for ‘fun’. It is really interesting to run the mouse over the graph and see the clouds corresponding to the graph peaks and dips. Just another enjoyable part of WD and weather.
When I swapped from a LaCrosse to VP2 all I had to do was show it the correct comm port and change the station type. It was very easy from a WD standpoint.
–Dave