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Weather Equipment/Software => Weather Station Siting & Setup Tips => Topic started by: administrator on December 15, 2005, 12:52:32 PM

Title: VP2 Upgrade Adventure
Post by: administrator on December 15, 2005, 12:52:32 PM
I need to think through the installation of my new VP2 (Thanks again Brian) :D

I'm replacing an OS WMR928 which has the T/H and rain gauge as separate sensors, and the VP2 has all the sensors in one stack. So where I was able to put the 928's T/H sensor in a shady place and the rain gauge in a rainy place I now have to find a location that suits all the sensors at once which may be tricky. Here's the problem (without pictures I'm afraid)...

The front garden is out. Too public and the chief garden designer wouldn't allow me to put it there even if I wanted to risk it! The back garden is well below the level of the house (the peak of the roof is about 35 feet above the garden), so the house casts quite a rain shadow over the garden. The prevailing wind (and rain) comes from the west and the house is due west of the garden #-o The garden also has a lot of mature trees/bushes on all sides, so the only place to put the rain gauge without run-off from vegetation would be in the middle of the lawn. With two boys (7 & 9 yo) in the house this isn't a viable position! So I don't think that ground mounting (well on a post in the ground) is an option.

My current rain gauge is mounted on the edge of the (flat) kitchen roof. It gets a reasonable view to the west but it's rather too high (16ft above ground level) and therefore likely to be impacted by wind blowing rain over it. Not much I can do about that though.

So this sort of fixes where I can put the ISS. However, this means that I have to put the T/H sensor in the same place. I don't think this is ideal though. There are lots of white painted walls which will reflect radiation in the sun and I suspect there will be a fair amount of reflected heat from the kitchen roof (it's metallised felt) in the summer. There's also the exhaust from the central heating system about 6 feet away (horizontally). Finally there is also a place nearby where a thin layer of water gathers on the flat roof after rain (the roofers clearly didn't get the drainage slope quite right) and this could affect humidity readings. I'm worried that all of these may affect the T/H readings. I've added an optional daytime FARS to Santa's delivery and this will help, but will it be enough to counteract the adverse conditions? Can anyone think of any other options open to me?

One other thought...the main difference between the daytime FARS and the 24 hours FARS appears to be a rechargeable battery. I don't know why there isn't an option to add a 24 hours FARS, but there isn't so I couldn't get one. However, is it possible to modify the daytime FARS to add a battery and therefore turn it into a 24 hour unit? It doesn't sound like a huge mod and it should be possible using the standard connectors, i.e. not cutting any wires. Has anyone done this, or is there some reason why it wouldn't work?
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 15, 2005, 02:12:25 PM
How about a on a tripod on that flat roof?

Is the solar panel bigger on the FARS with battery? If so I would question that capability of the standard panel to both run the fan and charge the battery.
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 15, 2005, 04:47:51 PM
Mounting isn't too much of a problem. I think I can mount the ISS on a pole on the house wall or the small wall that runs tound round part of the edge of the flat roof. The heating and humidity effect of the roof environment is the real concern. Maybe I'm overreacting...if the FARS is designed to cope with the ISS exposed in full direct sunlight, then maybe any extra radiation from the walls/roof isn't going to affect things very much?

The standard ISS appears to have one solar panel on the SIM (?) cover (I've not picked up all the new terminology yet!). There's a replacement SIM cover with the FARS unit which has two solar panels on it. It's difficult to tell from the small pictures I can find of the VP2 with 24-hour FARS, but that appears to have a single solar panel on the SIM cover and an additional solar panel alongside the radiation shield. The extra panel looks like it might be bigger than the one on the SIM cover, so maybe that's the difference...a bigger panel is needed to charge the battery and run the fan simultaneously. If that's true, then I would have thought it might be possible for someone to come up with an addon with a suitable solar panel plus battery that uses the same plugs/sockets as the FARS addon to turn it into a 24-hour model. I'd have thought that a suitable solar panel plus battery would only cost £15-20.
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 15, 2005, 04:50:10 PM
I've added an optional daytime FARS to Santa's delivery and this will help, but will it be enough to counteract the adverse conditions? Can anyone think of any other options open to me?

Yeah, I've got at least two excellent spots for an additional VP2.  Just put it back in the box and send it my way and your problem is solved. ;)
--Dave
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 15, 2005, 05:39:12 PM
Unless global warming has really toasted you already I think you'll be OK with the amount of solar radiation it'll get, I mean these things do pretty well in Arizona  :)

I'll cruise the Davis site a bit later, I'm not very up to speed with the VP2 options (trying to stay untempted, but now I'm thinking I might just slip one into the house painting bill  :wink: )
Title: Re: VP2 Upgrade Adventure
Post by: aifan27 on December 15, 2005, 08:03:08 PM
Glad to hear that you have upgraded to the VP2, Chris!  :)

It's pretty difficult to really say what you could do without any pictures...but the tripod idea that niko mentioned sounds like a good idea.  How far is the flat roof away from the house?

--Tim
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 15, 2005, 08:27:11 PM
Pictures are tricky...it's dark when I go to work and dark when I get home. Maybe I'll manage to grab some at the weekend.

The flat roof is attached to the house. It extends about 7ft south and about the same east, so the corner is about as clear a spot as I've got.
Title: Re: VP2 Upgrade Adventure
Post by: mah291069 on December 15, 2005, 08:34:17 PM
Chris, you lucky BLEEP getting a VP2  :lol:
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 15, 2005, 08:48:26 PM
Just taking all the bits out of the box and reading the manual (yes actually reading it) to see how they all fit together!
Title: Re: VP2 Upgrade Adventure
Post by: aifan27 on December 15, 2005, 08:56:40 PM
To tell you the truth, I'm really curious to see how well the drip ring on the anemometer works out...

We're expecting a significant amount of sleet/ice here (possibly up to 0.25" of it  8O) and it's supposed to be breezy.

--Tim
Title: Re: VP2 Upgrade Adventure
Post by: Weather Display on December 15, 2005, 09:01:20 PM
if you live on or near hill tops/ridges, then your overnight temperatures can be alot higher than people in the same area who live in hollows/basins/flat areas ...
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 15, 2005, 10:59:47 PM
I'm making progress...

Console setup and data logger installed.
Anemometer set up and connected to transmitter
Rain gauge set up for 0.2mm.tip (what is the 0.1mm/tip setting for on the console?)
FARS built and connected to ISS.

That's enough for tonight. I need to get the serial to USB adapter next so that I can hook the console up to the PC and get WL installed. Then it's outside when I can get a man with a ladder to climb up high and bring my anemometer mast down to ground level.
Title: Re: VP2 Upgrade Adventure
Post by: mah291069 on December 15, 2005, 11:05:17 PM
I need to get the serial to USB adapter next so that I can hook the console up to the PC and get WL installed.


Sounds good. I have a new toy waiting to be set up too - a new PC is sat on the floor at the moment - I am waiting on a serial to USB converter too so I hope my lowly WMR928N works ok with that or I will have to get a serial port PCI card!!! I am away at the weekend so the new PC will have to wait until Monday to be powered up. So my weather data may disappear for a while.

One day I will get a Davis!

Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 15, 2005, 11:08:19 PM
Is it normal for the outdoor T/H sensor to give different readings to the indoor sensors (when they're in the same place)? I've got the console sat on top of the rain gauge, so the sensors are very close. The console is currently showing 19degC for outdoor and 22degC for indoor (my OS T/H sensor about 4 feet away is saying 21degC. Humidity is also different (53% outdoor and 45% indoor), but this might just be down to the temp difference. The console and ISS have been together in the same room for 24 hours, so they should have reached a stable and similar temp.

I'll monitor it for a while longer, but is this to be expected?
Title: Re: VP2 Upgrade Adventure
Post by: Weather Display on December 15, 2005, 11:11:31 PM
is the light on, on the console?
also the rain gauge is black...try moving it away from that
also i dont think the specs on the indoor temperature as as accurate as the outdoor temperature...so differences will occur...
Title: Re: VP2 Upgrade Adventure
Post by: gdumbleton on December 15, 2005, 11:20:10 PM
I just went through this with mine. I had a weather monitor II that was zapped with a serge from the computer and bought the VP2.

I did as you have done and put them in the same room for a long time. I would say that they should read the same if they are in the same room for a reasonable length of time. There is a way of adjusting that. If you look in your manual to see the procedure. The only thing that is the unknown is which temperature is the correct one so that you can adjust the right one.

I got another thermometer to put in the same place and decided which one was correct. Unless you have a hygrometer, it is a tossup about the humidity. I adjusted mine assuming that the indoor one was correct and may need to refine that based on humidity readings in my area.

This was my experience and method for doing this.

Gary
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 16, 2005, 12:16:45 AM
also i dont think the specs on the indoor temperature as as accurate as the outdoor temperature...so differences will occur...
I think this may have been true before but acc to the vp2 manual on the website they are both +/- 0.5 deg C. I'm not surprised by the discrepancy Chris is seeing though, there are so many possibilities for air currents or other effects acting differently on the two sensors. If it was all wrapped in a thermal insulating blanket for a while then I would expect them to the same within the limits of the spec.
Title: Re: VP2 Upgrade Adventure
Post by: zanman on December 16, 2005, 12:49:21 AM
I have my VP2 set up on the roof using a TV aerial stand - the bottom of the unit is a touch over 2 metres higher then the peak of the roof.
When I set it up, I had three different weather stations all located in a close proximity with all of them showing very similar data so didn't need to tweek anything.
Old Chinese Proverb - "Man with one watch always know time, man with two watch never know time"

Temperature radiation from the roof was my biggest concern on installing there, but I also had issues with location in the garden area - too many trees and shrubs - so up there it went. Temperatuers readings seem to closely mirror other data in the general area, so I am quite happy with the readings I get . In New Zealand of course it is unusual to have no wind at all to flow over the sensors so roof radiation is not usually an issue. Obviously, up there grass temperatures get missed.
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 16, 2005, 01:10:40 AM
Is that a "hot tin roof" ?
Title: Re: VP2 Upgrade Adventure
Post by: zanman on December 16, 2005, 02:55:25 AM
Is that a "hot tin roof" ?

Meow
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 16, 2005, 03:10:21 AM
 :lol:
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 16, 2005, 07:32:34 AM
The temp differences have settled down overnight which seems odd. Temps are now 16/17 (out/in) and humidity readings are now 61/57 (out/in).

They're close enough now (bearing in mind the +/- 0.5deg accuracy).
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 17, 2005, 09:36:06 AM
Some pictures (now that it's light enough!)

Looking West, this puts the current sensor positions in context...

A) Anemometer
B) 2m/70cm vertical antenna
C) Rain Gauge
D) G5RV wire antenna

Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 17, 2005, 09:38:42 AM
Looking North-East (two pics...one from inside which has some reflection from the glass)...

Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 17, 2005, 09:40:43 AM
Looking South-East (difficult shot with the sun this morning)...

Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 17, 2005, 09:43:18 AM
Looking North-West...
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 17, 2005, 09:47:07 AM
Looking South-West (rain gauge can just be seen on this)...
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 17, 2005, 09:53:30 AM
Last one. Looking West showing the rain gauge position better. The flat roof is about 12ft wide (East-West) and the gauge is probably about 12ft South from side wall of the house.
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 17, 2005, 11:16:02 AM
Having thought about this some more, I think if I ever want to add solar and/or UV sensors then I'll have to mount it somewhere near the current rain gauge. Anywhere else won't see enough of the sun. I assume it's not possible to mount these sensors away from the ISS? That's a little odd in a way, because they really need to be up above the roof, yet this isn't really the ideal place to site a rain gauge or the T/H sensor.
Title: Re: VP2 Upgrade Adventure
Post by: Foggy on December 17, 2005, 11:50:18 AM
I think if I ever want to add solar and/or UV sensors then I'll have to mount it somewhere near the current rain gauge. Anywhere else won't see enough of the sun. I assume it's not possible to mount these sensors away from the ISS? That's a little odd in a way, because they really need to be up above the roof, yet this isn't really the ideal place to site a rain gauge or the T/H sensor.

Yes it is possible.. but since the power output of the UV/solar sensors is very low they will transmit lower readings. I am very weary about sending my solar sensor up there.. would a solution  be to just increase the Wm offset% through weather display?

In New Zealand of course it is unusual to have no wind at all to flow over the sensors so roof radiation is not usually an issue.

It's a big issue here, as for places in basins.. like Kawerau, Alexandra, reefton etc.. That was a reason I didn't send it up there on the pole above the roof.. the variance would be far too much.
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 17, 2005, 12:17:41 PM
I wasn't proposing roof mounting because the readings would be lower (I doubt if an extra 20ft would make a huge difference after the light has travelled through around 100 miles of the Earth's atmophere). The reason for roof mounting is to ensure that they can see the sun as much as possible between sunrise and sunset. I thought the ideal place for mounting a rain gauge was in a reasonably large clearing in a group of trees...which is just the place you wouldn't want to put a solar/UV sensor!
Title: Re: VP2 Upgrade Adventure
Post by: weatheroz on December 17, 2005, 12:39:18 PM
I wasn't proposing roof mounting because the readings would be lower (I doubt if an extra 20ft would make a huge difference after the light has travelled through around 100 miles of the Earth's atmophere). The reason for roof mounting is to ensure that they can see the sun as much as possible between sunrise and sunset. I thought the ideal place for mounting a rain gauge was in a reasonably large clearing in a group of trees...which is just the place you wouldn't want to put a solar/UV sensor!
Well I've got my ISS 1.5m above ground on a pole, and even though there's no real shade to speak of, I start to get low UV readings from after 3pm (sunset is around 6:40pm), so you might be fairly safe having them where your rain gauge currently is.
 
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 17, 2005, 02:48:30 PM
Just a thought on my part and could be absolutely wrong.  But any site you look at has a bell curve for the graph. 

I don't think it matters how open the area is, as it is the angle the light hits the sensor unless of course it's shielded by trees, buildings or whatever.  When I was testing mine I could see on the graphs where the sensor had been pointed at the sun verses a level position.  I think the only way you could get a true reading would to have a tracking device that kept the sensor pointed directly pointed at the sun at all times (like one of the star tracking telescopes) or a program that would calculate the solar energy based on the time and angle of the sun in relation to the sensor.  But then again what the heck do I know.

--Dave
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 17, 2005, 03:38:15 PM
The bell curve is probably partly related to the inability of the sensors to operate well at low sun angles. However, even if you tracked the sun, you would still get a bell curve. Solar radiation, including UV, is greater at noon (approx) because that's the time when it's coming through the least atmosphere. In the morning and evening the radiation has to pass through a lot more atmosphere to reach you, so more of it is 'lost' on the way to the sensor. That's why you get sunburn much quicker at noon than at 0800!
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 17, 2005, 03:50:54 PM
By using Stuart's program you can see the expected max solar radiation vs the time which I assume takes that into account.  So if the sensor was pointed directly at the sun and the expected max radiation was 10 and the sensor saw and read 10 because of no angle to the sensor it would being seeing 100% of the max radiation.  The only time you would have less than the expected max would be due to clouds. 

So in my feeble mind, on a perfectly clear day with a view from horizon to horizon and a sensor pointed directly at the sun you would never go below 100% thus no bell curve.

--Dave
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 17, 2005, 04:04:52 PM
I think Stuart's program calculates the time of the maximum solar radiation for each day and the level of radiation expected at that time. The radiation either side of the maximum falls away to zero at sunrise/sunset.

This is shown in the data from an observatory like Mt Teide on Tenerife...http://www.iac.es/weather/otdata/rad_net.html
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 17, 2005, 04:14:24 PM
I'd bet their sensors aren't pointed directly at the sun.  I guess my point is if the max calculated radiation can be measured then no matter the value, even if .001, then 100% because your seeing the max that can be expected at that time.

Didn't someone on here have a sensor made of 3 solar cells from a calculator because he was trying to get closer to the angle of the sun during the day?  I think 180 solor sensors in an array would smooth out the curve greatly.

--Dave
   
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 17, 2005, 04:36:48 PM
I wasn't proposing roof mounting because the readings would be lower (I doubt if an extra 20ft would make a huge difference after the light has travelled through around 100 miles of the Earth's atmophere). The reason for roof mounting is to ensure that they can see the sun as much as possible between sunrise and sunset. I thought the ideal place for mounting a rain gauge was in a reasonably large clearing in a group of trees...which is just the place you wouldn't want to put a solar/UV sensor!

You can extend the cable for the solar sensor, 30 - 40 feet is not a problem. I mounted mine on the (unused) chimney with the anemometer to get it in a clear position. Noise will add some inaccurancy but it should be acceptable relative to the accuracy of the measurement itself.
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 17, 2005, 04:48:53 PM
What shape do you think the daily solar plot would be if the sensor tracked the sun? Maybe I'm misunderstanding what you're saying. It seems like you're saying that on a clear day with a sensor tracking the sun you'd get a straight line rather than a curve? Experience suggests that's not the case. On a sunny day stand in the sun at 0800, 1200 and 1600. You will feel much hotter in the sun at 1200 than at 0800 or 1600 because the solar radiation for the day is at it maximum (approx) at that time.
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 17, 2005, 04:53:18 PM
Just a thought on my part and could be absolutely wrong.  But any site you look at has a bell curve for the graph. 

I don't think it matters how open the area is, as it is the angle the light hits the sensor unless of course it's shielded by trees, buildings or whatever.  When I was testing mine I could see on the graphs where the sensor had been pointed at the sun verses a level position.  I think the only way you could get a true reading would to have a tracking device that kept the sensor pointed directly pointed at the sun at all times (like one of the star tracking telescopes) or a program that would calculate the solar energy based on the time and angle of the sun in relation to the sensor.  But then again what the heck do I know.

--Dave

That "bell curve" is exactly what this sensor should produce, it does not measure direct solar radiance which is measured with the sensor tracking the sun, it measures the the radiance on a horizontal surface, which will depend on the angle of the sun.
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 17, 2005, 04:56:09 PM
What shape do you think the daily solar plot would be if the sensor tracked the sun? Maybe I'm misunderstanding what you're saying. It seems like you're saying that on a clear day with a sensor tracking the sun you'd get a straight line rather than a curve? Experience suggests that's not the case. On a sunny day stand in the sun at 0800, 1200 and 1600. You will feel much hotter in the sun at 1200 than at 0800 or 1600 because the solar radiation for the day is at it maximum (approx) at that time.


Right, you would get a different curve due to the changing attenuation through the atmosphere and then some other effects at really low angles.
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 17, 2005, 04:56:36 PM
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).
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 17, 2005, 04:58:37 PM
Yes, the console will compensate based on the altitude you plugged in. WD gets the raw value and does its own compensation.
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 17, 2005, 05:33:45 PM
That "bell curve" is exactly what this sensor should produce, it does not measure direct solar radiance which is measured with the sensor tracking the sun, it measures the the radiance on a horizontal surface, which will depend on the angle of the sun.
Agree completely.  Sensor on a horizontal plane will and must produce a bell curve.  Sensor pointed directly at the sun at all times without interference will not produce such a curve.  Thanks for the discussion guys!

Back on topic:  Good luck with the VP2 and see the USB version is working for you.  I think that makes two of us. :)
--Dave
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 17, 2005, 06:03:34 PM
But it's not as cute as a Cambell Stokes http://www.russell-scientific.co.uk/meteorology/campbell_stokes_sunshine_recorder.html
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 17, 2005, 06:22:49 PM
Sensor pointed directly at the sun at all times without interference will not produce such a curve.

But it will still produce a curve, just with shallower gradients?

BTW the VP2 is serial...but I'm using a serial to USB converter because the PC only has a single COM port and I need two ports.
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 17, 2005, 06:48:33 PM
But it will still produce a curve, just with shallower gradients?

That was my opinion a few posts back, I don't think he is taking the atmosphere into account.
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 17, 2005, 06:53:04 PM
Quote
But it's not as cute as a Cambell Stokes

Wow, I like that.  I see a Feature Request coming....  Brian... can WD import the output of a Cambell Stokes??? ;)
Well all in all, I think my webcam is a better solar detector.

Sorry misunderstood about the USB.  Guess it's a party of one.

--Dave
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 17, 2005, 06:59:10 PM
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?
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 17, 2005, 07:07:54 PM
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
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 17, 2005, 07:15:05 PM
That was my opinion a few posts back, I don't think he is taking the atmosphere into account.
You're correct.  I'm thinking the values from the table were only calculating for the angle of incidence.  So in my theory, you calibrate a sensor, tracking the sun, for 'clear atmosphere' and then you get a straight line on a sunny day.
That's why I posted this.  Just trying to learn. 
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 17, 2005, 07:30:31 PM
You're correct.  I'm thinking the values from the table were only calculating for the angle of incidence.  So in my theory, you calibrate a sensor, tracking the sun, for 'clear atmosphere' and then you get a straight line on a sunny day.
That's why I posted this.  Just trying to learn. 
Hey, that's cool, it's a discussion group :)

If you take out the effect of the atmosphere you get the "solar constant" = 1,370 watts/sq meter = the solar radiation at the top of the atmosphere. 10% or more will be lost on the way down.
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 17, 2005, 09:42:14 PM
then you get a straight line on a sunny day.

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:
Title: Re: VP2 Upgrade Adventure
Post by: Kojack on December 17, 2005, 11:05:12 PM
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. )
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 18, 2005, 01:37:35 AM
I'm glad we all meant the same thing once we worked out what we were saying :lol:
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
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 18, 2005, 07:22:16 AM
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.
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 18, 2005, 01:21:38 PM
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.

--Dave
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 18, 2005, 03:42:55 PM
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.


If the sky was perfectly clear from sunrise to sunset the curve (of watts/meter sq) from the Davis sensor will be a sine curve.
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 19, 2005, 03:43:56 PM
I'm one step nearer to 'VP2 go'. I've spent the afternoon putting up a wall bracket and an 8ft metal pole. The ISS is now mounted on it.

Next job is to get an aerial rigger to replace my WMR928 anemometer with the VP2 one.

Then it's the big job...swap over from the WMR928 to the VP2 in WD. I might need some clues along the way there!

Title: Re: VP2 Upgrade Adventure
Post by: niko on December 19, 2005, 04:13:41 PM
if you didn't do it already I suggest testing the anemometer before it gets installed on the roof :)
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 19, 2005, 04:22:05 PM
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
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 19, 2005, 04:45:05 PM
The anemometer did work when I put it together, but I'll try it again before it goes up in the sky.

The kind of things I'm thinking about with the swap over are (and these are to remind me as well!)...

1) With the faster wind speed updates I could tweak my clientraw update frequency
2) I've got some extra sensors with the WMR928 which don't have equivalents on the VP2
3) The WMR928 needs a big baromete offset which will need removing.
4) I'll need to make sure the VP2 is using the same barometer values (local v SLP) in WD as the OS station
5) The COM port will need to change
6) I'll have to work out how to enable the VP2 data logger
7) I can presumably grab the VP2 forecast text now and make it available on my web page
8) My web page says the data is from a WMR928
9) Probably some more things!
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 19, 2005, 04:56:33 PM
One word - "backup"
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 19, 2005, 04:57:58 PM
One word - "backup"

Errr...what's one of those?
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 19, 2005, 05:00:16 PM
6) I'll have to work out how to enable the VP2 data logger

My LaCrosse was serial and VP2 is USB.  I was running both at the same time so mine may have been easier than what you're doing.  

You may want to fire up a second WD, get the VP running on it then make the switch.  I did install the WeatherLink software to make sure the VP was responding out of the box and to set the parms for the logger but haven't touched it since.

--Dave  
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 19, 2005, 05:01:26 PM
You may want to fire up a second WD, get the VP running on it then make the switch.
I like that idea too.
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 19, 2005, 05:05:43 PM
I've been thinking about doing that. I've got WL monitoring the VP2 on the same PC as WD is running on. I could install a second copy of WD just to make sure that WD was talking correctly to the VP2, but I think I'd still want to switch my current WD over to the VP2. It's got all the settings/configs in it that I've painfully crafted over the years and I wouldn't like to have to start again from scratch! I know I could fidde with INI files and the registry to make them match, but I'm not sure if there's any great benefit in that.
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 19, 2005, 05:14:51 PM
I'm suggesting you practice setting up the VP with WD, mess with the options etc, and then you can convert your main (now OS) install.
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 19, 2005, 05:48:41 PM
ISWYM.

The good news so far is that the VP2 in it's allocated position is tracking the OS outdoor temperature exactly a lot of the time, although it's been up to 0.2 degC out on occasions. That's pretty close though. It will be interesting to see what it's like if/when we get some sun...the VP2 is exposed and the OS is in the shade.
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 20, 2005, 03:52:18 PM
The VP2 seems to be working OK with WD and the temps, humidity and barometer seem to be tracking each other pretty well, so the change of equipment and location probably isn't going to dramatically affect my records. We got a bit of sun today, but not enough to make any real difference to the temperature, so I don't know how the VP2 temp sensor will behave under those conditions yet.

Tomorrow is probably the swap over day. I've got a man coming with a ladder to take my mast down, remove the WMR928 anemometer and fit the VP2 anemometer. I've checked that the anemometer is working OK and I'll make sure the allen screws are tight. Is there anything else I need to make sure I do with it before I put it way up high (out of reach)?
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 20, 2005, 04:34:36 PM
Make sure he knows north from south??? ;)
Do you have a remote transmitter or using the cable to ISS?  May want to decide the best route and how to secure the cable run and is it long enough.  I had to extend my by about 10' or 3 meters by your measurement.
--Dave
Title: Re: VP2 Upgrade Adventure
Post by: NorCal Dan on December 20, 2005, 04:58:13 PM
There was mention in another thread about using something like rainx on the anenometer.  I think a good paste wax might be just as effective.  Do yu get freezing rain at your location?  Thats about all I can think of...
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 20, 2005, 08:28:13 PM
I know which way North is. Luckily the wall that the mast is on is pretty much spot on N-S which makes mounting anemometers really easy. I've got an anemometer transmitter, but I'll mount it where I can get to it rather than up the pole.

Freezing rain isn't an issue in this area so I don't intend adding any type of protection for it. I've had anemometers up on this and my previous house for about 5 years now and I've not had a problem so far.
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 20, 2005, 08:44:06 PM
I know which way North is.

That was a joke.  I knew you would.  You can't like the weather and not know which way is North; unlike my wife.  One day my Dad asked her where the sun rose at our new house and she said that when we were in our other house it rose in the East but wasn't sure about the new house yet.  Gotta love her.  I won't even tell you what she thought about driving to Alaska.

--Dave
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 20, 2005, 09:07:12 PM
Sorry...I missed a smiley.

Driving to Alaska? There must be a joke in there somewhere?
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 20, 2005, 11:09:39 PM
That was a joke.  I knew you would.  You can't like the weather and not know which way is North; unlike my wife.  One day my Dad asked her where the sun rose at our new house and she said that when we were in our other house it rose in the East but wasn't sure about the new house yet.  Gotta love her.  I won't even tell you what she thought about driving to Alaska.

--Dave

Some years ago we had some visitors at work who got up very early on a Saturday morning and drove to the beach to watch the sunrise over the Pacific - they said they did because it they liked to do it back home in New Jersey   #-o
Title: Re: VP2 Upgrade Adventure
Post by: weatheroz on December 20, 2005, 11:33:37 PM
I know which way North is. Luckily the wall that the mast is on is pretty much spot on N-S which makes mounting anemometers really easy. I've got an anemometer transmitter, but I'll mount it where I can get to it rather than up the pole.

Just mount the transmitter down at the base of the pole, as there should be more than enough cable to have the anemometer up the top of the pole to get to the bottom of it.

That's what I'm planning on doing when I can get some help on a still day... unfortunately have had the help ready go on days when it's been a bit breezy, but not on still days. :(
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 21, 2005, 12:25:42 AM
Sorry...I missed a smiley.
Driving to Alaska? There must be a joke in there somewhere?
Actually I didn't put a smiley in as I thought it was so obvious.  My bad.

Some friends of ours were talking about driving to Alaska and my wife burst out laughing that anyone would think they could drive there.  Later I asked her why and she said that you couldn't drive to Alaska because it was an island.  I asked why she would think that and she found a map of the US which had the continuous states and Hawaii and Alaska shown off to the side surrounded by blue.  To her they both had to be islands.  That was years ago and she now has a better grasp of the world.  Boy am I glad she doesn't care or know how to use computers.

Chris, did you get the second WD running and recording?

--Dave
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 21, 2005, 07:34:12 AM
I assumed the Alaska thing was about how far it was, but I know what you mean about it being an island.

Yes...WD a second copy of WD is running now talking to the VP2.

Even the bottom of the pole the anemometer is on is too high to reach without a ong ladder, so I'll be bringing the transmitter down much lower!
 
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 21, 2005, 04:23:18 PM
Yippeee...I'm now live on the VP2. I think that putting the anemometer up has stopped the wind though. 10 minute average is just 1mph!
Title: Re: VP2 Upgrade Adventure
Post by: NorCal Dan on December 21, 2005, 04:29:56 PM
Congrats.  Glad everything worked out for the switch over.
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 21, 2005, 04:37:14 PM
It will take a while to spot all the bits that I no longer have. For example, I've remove the solar and ET info from the web pages, but then noticed that it's also included in the summary image #-o

10 minute wind average is now zero!
Title: Re: VP2 Upgrade Adventure
Post by: NorCal Dan on December 21, 2005, 04:47:42 PM
Looks ok from here...avg wind 0.8 MPH
Title: Re: VP2 Upgrade Adventure
Post by: niko on December 21, 2005, 05:16:42 PM
5 MPH SW, wait a minute, MPH ?  8O
Title: Re: VP2 Upgrade Adventure
Post by: Kojack on December 21, 2005, 05:49:30 PM
Phew!!!!!
Great result Chris.
After your saga I think I'll stick to my 928  :(   -so much for dreams. I have enough problems tweaking my 928 and the thought of what for me would be about 4 week's work is enough to send me to the local home for the confused elderly.

I'm jealous really and I think the Davis Santa's forgotten that I moved three years ago . [-o< for a miracle
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 21, 2005, 06:55:37 PM
5 MPH SW, wait a minute, MPH ?  8O

We still use that here...we're pragmatically metric :wink:
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 21, 2005, 06:57:30 PM
After your saga I think I'll stick to my 928  :(

It wasn't that bad really, so keep on with the dream.
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 21, 2005, 07:03:18 PM
Glad to see you got it all working.  Plans for solar next?  I haven't had mine for more than a month and think I would miss it already.

I was checking out you site and see that you have the forecast being 'scrolled' below the main icon.  What did you do to enable that?  I have the Davis forecast being replaced by a NOAA forecast but didn't know it was possible to animate it on the web page.

--Dave
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 21, 2005, 08:18:50 PM
I was checking out you site and see that you have the forecast being 'scrolled' below the main icon.  What did you do to enable that? 

I think...

Control Panel > Summary image/icons > Main Screen Icon Setup > Show the David VP...

Solar...eventually, but I need to save up first! The UV sensor is even more frighteningly priced! I must get round to trying to build one first though.
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 21, 2005, 08:35:46 PM
Control Panel > Summary image/icons > Main Screen Icon Setup > Show the David VP...
I have it displaying and scrolling on my WD at home but not on the web page from my site.  That's what I'm after.
--Dave
Title: Re: VP2 Upgrade Adventure
Post by: administrator on December 21, 2005, 08:40:42 PM
Ahhh...I think I know what it is. I have the console graphic animating showing the conditions at 1 minute intervals and the snapshots just happen to make it look like the forecast is scrolling across. If you look closely you'll see it jump on each time the clock jumps on.
Title: Re: VP2 Upgrade Adventure
Post by: daveq on December 21, 2005, 08:54:45 PM
Yeah, that appears to be it.  I didn't notice the other data being animated.  Thanks.
--Dave