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Davis VP2 Relay Device

For discussion of DIY weather equipment - sensors, accessories, improvements to existing kit etc
Herbaldew
Posts: 100
Joined: Sun 12 Mar 2017 8:33 pm
Weather Station: VP2+
Operating System: Raspberry Pi OS (32-bit)
Location: US Mid-Atlantic

Re: Davis VP2 Relay Device

Post by Herbaldew »

mcrossley wrote:only one question are they far enough in front of the mast so they aren't shadowed at midsummer?

At my latitude the Sun rises/sets at midsummer approximately 45 degrees either side of North.
Turns out the answer is "no". Looks like I have about the same measurements here and I have a little bump in the chart at sunrise and sunset.

How far out from mast do you have your sensors?

Looking at the photo below, wouldn't I be better of with them on the north side of the mast?

Thanks - Herb

Image
Last edited by Herbaldew on Wed 23 Aug 2017 5:24 pm, edited 1 time in total.

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mcrossley
Posts: 6740
Joined: Thu 07 Jan 2010 9:44 pm
Weather Station: Davis VP2
Operating System: Buster Lite rPi
Location: Wilmslow, Cheshire, UK
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Re: Davis VP2 Relay Device

Post by mcrossley »

Herbaldew wrote:Looking at the photo below, wouldn't I be better off mounting the sensors on the north side of the mast?
Nope! Then the sensor would be shaded every day!

As you have your sensors side-by-side they will have to further out than if they were inline with the mast. This very poor sketch shows where they need to go...
IMG_20170823_171332-01.jpeg
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Herbaldew
Posts: 100
Joined: Sun 12 Mar 2017 8:33 pm
Weather Station: VP2+
Operating System: Raspberry Pi OS (32-bit)
Location: US Mid-Atlantic

Re: Davis VP2 Relay Device

Post by Herbaldew »

I think this will do it - find out for sure next June ;)

Image

AllyCat
Posts: 1073
Joined: Sat 26 Feb 2011 1:58 pm
Weather Station: Fine Offset 1080/1 & 3080
Operating System: Windows XP SP3
Location: SE London

Re: Davis VP2 Relay Device

Post by AllyCat »

Hi,
Herbaldew wrote: - find out for sure next June ;)
Or tell us your site Latitude and we can probably work it out now. ;)

Cheers, Alan.

Herbaldew
Posts: 100
Joined: Sun 12 Mar 2017 8:33 pm
Weather Station: VP2+
Operating System: Raspberry Pi OS (32-bit)
Location: US Mid-Atlantic

Re: Davis VP2 Relay Device

Post by Herbaldew »

38 North -75 West

I'm confident it is good with an inch or two to spare. I printed out that "rose" above and taped it to a large piece of cardboard. Then drew lines like in Mark's sketch laying out my "safe zone". Then took the actual mount and laid on the cardboard sliding it out from center (actually from the where the south side of the mast would be) until the sensors where in the "SZ", then added a couple inches just to be safe.

AllyCat
Posts: 1073
Joined: Sat 26 Feb 2011 1:58 pm
Weather Station: Fine Offset 1080/1 & 3080
Operating System: Windows XP SP3
Location: SE London

Re: Davis VP2 Relay Device

Post by AllyCat »

Hi,

For Latitude 38 degrees, the maximum day length appears to be 14.75 hours or about 220 degrees (i.e. from 70 to 290 degrees azimuth). So it looks as if you should be alright, but may need to also consider the diameter of the mast and sensor, and possibly reflections from the mast.

BTW a maximum of 18 hours daylight / 270 degrees appears to correspond with latitude 57 degrees, which is about mid-Scotland for us and Canada for you.

Cheers, Alan.

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mcrossley
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Weather Station: Davis VP2
Operating System: Buster Lite rPi
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Re: Davis VP2 Relay Device

Post by mcrossley »

AllyCat wrote:BTW a maximum of 18 hours daylight / 270 degrees appears to correspond with latitude 57 degrees, which is about mid-Scotland for us and Canada for you.
<pedantMode>Taking refraction into account 54.5N gives 270 degrees, but only 17h16m of daylight?</pedantMode>

Herbaldew
Posts: 100
Joined: Sun 12 Mar 2017 8:33 pm
Weather Station: VP2+
Operating System: Raspberry Pi OS (32-bit)
Location: US Mid-Atlantic

Re: Davis VP2 Relay Device

Post by Herbaldew »

Herbaldew wrote:Oops! I had a max wind of 253 MPH today.
Phantom gust number two last night - at least it was slower at a mere 190 MPH this time lol


Edit: Problem solved - see 2020 posts.
Last edited by Herbaldew on Tue 21 Jul 2020 10:27 pm, edited 1 time in total.

AllyCat
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Joined: Sat 26 Feb 2011 1:58 pm
Weather Station: Fine Offset 1080/1 & 3080
Operating System: Windows XP SP3
Location: SE London

Re: Davis VP2 Relay Device

Post by AllyCat »

Hi,
mcrossley wrote: <pedantMode>Taking refraction into account
Is it actually refraction, or mainly due to the "complexities" of the 3D geometry? I believe the (atmospheric) refraction is around 0.6 degree, which I wouldn't have thought could account for more than a few minutes of day length. But I realised when writing my post above, that the calculation of the azimuth for any given time might not be as simple as implied.

Although I have written (or to be honest adapted) a program to calculate sunrise and sunset times for any location and date, I've not yet extended it to calculate the sun's azimuth for any given time. One reason for that is the "model" calculation (written by a University lecturer) that I originally adapted, proved to be demonstrably wrong! So I then planned to "borrow" the nicely-documented calculation in your "sun plot" application, but haven't got around to doing that yet.

Cheers, Alan.

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mcrossley
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Weather Station: Davis VP2
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Location: Wilmslow, Cheshire, UK
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Re: Davis VP2 Relay Device

Post by mcrossley »

Hmm, fag packet calculation, at mid-summer for 54.5N, refraction extends the day approximately 22 mins, the azimuth angle by ~ 5.5 degrees (11 minutes, and 2.25 degrees at both sunrise and sunset). Is that enough I wonder?

safuser
Posts: 2
Joined: Sun 04 Sep 2016 12:25 pm
Weather Station: Davis VP2
Operating System: Win10

Re: Davis VP2 Relay Device

Post by safuser »

So I have RxTX successfully running on a Moteino and relaying to my VP2 console. Am attempting to get ISSRx and AnemometerTx to work on a Adafruit Feather 32u4 & M0 and having a few issues. The board seems to be freezing in setup at at the " radio.initialize(FREQ_BAND_US);" line?

I have added the following to DavisRFM69.h but am not sure the IRQ & PIN #s are correct? Found in another post & not sure I am reading pinouts right?

#elif defined (__AVR_ATmega32U4__) // Feather 32u4 w/Radio
#define RF69_IRQ_PIN 3
#define RF69_IRQ_NUM 0
#elif defined(ARDUINO_SAMD_FEATHER_M0) // Feather M0 w/Radio
#define RF69_IRQ_PIN 3
#define RF69_IRQ_NUM 3

Is there anything else that would need to be added/changed?

Also should BW_WIDE or BW_NARROW be used in US?


Any advice would be greatly appreciated!

Phil23
Posts: 508
Joined: Sat 16 Jul 2016 11:59 pm
Weather Station: Davis Vantage Pro2 Plus
Operating System: Win7 Pro
Location: Australia

Re: Davis VP2 Relay Device

Post by Phil23 »

mcrossley wrote:
Sun 01 Jan 2017 1:49 pm
New Year = New Project!
After having a read over this thread several times in the last few years, I've just had a lightbulb moment.

This project is not far off being converted to an additional ISS transmitter.

Lets face it, extra stations here & there would be great for stuff like soil temp, pool, river tank water etc, as well as fudging in air quality with a sensor discussed here...
https://www.siliconchip.com.au/Issue/20 ... e+BackPack

Catch has always been the prohibitive cost of the Davis units.

As you've successfully collected & relayed data, it seems the only code to be added would be to read say DS18B20 temp sensors (accurate enough for many tasks), & what other inputs were desired.

Would be so good to have the additional data available & sitting up on the CMX pages.


Cheers

Phil.

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laulau
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Weather Station: WeatherDuino Pro2
Operating System: Win 7
Location: Meyenheim, Alsace, FR
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Re: Davis VP2 Relay Device

Post by laulau »

Hi Mark,

i have an arduino with a RFM95 shield, do you think it's possible that it works with this module ?

Thanks
Laurent

Image

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mcrossley
Posts: 6740
Joined: Thu 07 Jan 2010 9:44 pm
Weather Station: Davis VP2
Operating System: Buster Lite rPi
Location: Wilmslow, Cheshire, UK
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Re: Davis VP2 Relay Device

Post by mcrossley »

I'm not sure, people have used the base library with other radio modules with slight tweaks to the code. You may find some more information if you search the WX forum.

Phil23
Posts: 508
Joined: Sat 16 Jul 2016 11:59 pm
Weather Station: Davis Vantage Pro2 Plus
Operating System: Win7 Pro
Location: Australia

Re: Davis VP2 Relay Device

Post by Phil23 »

Phil23 wrote:
Fri 14 Feb 2020 9:42 pm
This project is not far off being converted to an additional ISS transmitter.
After looking about for a few more days, I how get that this is pretty much the basis of what I was thinking, just not sure if I can get my head around the changes required for it to be say an additional temp or soil station.

Then there's the Aussie 915MHz frequency requirement; have only read a little on that, but see that they are supported.

Phil.

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