SVSS Weather Station - RC Groups
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Nov 17, 2010, 12:16 PM
Team Hello Kitty
SoaringDude's Avatar
Discussion

SVSS Weather Station


It was great to see the club vote "yes" on the Weather Station project at the 11-13 meeting pending the final field lease with the county.

The next step is to hear back from the Yolo Bowmen by this Saturday (11-20) and see if they are willing to let us install the weather station equipment and Internet satellite dish at their clubhouse.

If we get a thumbs up, I'll post a link to a special Wx Station project website that has equipment details, how it works, next steps, latest cost estimates, etc.

One more thing: based on a question from a club member about possible reliability issues with the weather equipment, I did more research and found an excellent weather enthusiast forum with lots of feedback on the equipment we are planning to use.

Nov 20 update: we just got the green light from the Yolo Bowmen organization to move forward with our weather station project! With that I am now publishing the Weather Station Project Website. Full details are there.

Chris B.
Last edited by SoaringDude; Nov 20, 2010 at 06:51 PM. Reason: Nov 20 update
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Nov 17, 2010, 04:41 PM
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Quote:
Originally Posted by SoaringDude
It was great to see the club vote "yes" on the Weather Station project at the 11-13 meeting pending the final field lease with the county.
Chris,

Would you post a few links to the weather station you propose as well as the satellite service? I would like to study them a bit. Thanks!

Jon
Last edited by jpherit; Nov 17, 2010 at 09:32 PM.
Nov 17, 2010, 11:25 PM
Team Hello Kitty
SoaringDude's Avatar
Hi Jon,

Sure, here are a few links. And if it's a "go" this weekend I'll post a link to the wx station project site that has more details.

WildBlue Satellite Internet "WildBlue Value" is what we would get since it's more than enough for the wx data transfers. They say installation is "free" but for us it will probably cost ~$70.

Vantage Vue wireless weather station by Davis Instruments The Vantage Pro2 is their more expensive unit but does not give us any real advantages. We will also need the yagi antenna Davis p/n 7660. Details later.

WeatherPlug This replaces what normally would be a PC that receives the Vantage Vue wx data and streams it live to the WeatherUnderground website as well as other custom weather displays we can set up.

Weather Underground example personal weather station We will be able to configure our weather data to look like this. We could also display PWS "stickers" that show real-time wx on the SVSS website if Dudley wants to add it.

More soon...

Chris B.
Nov 18, 2010, 02:32 PM
Registered User
Quote:
Originally Posted by SoaringDude
Hi Jon,

Sure, here are a few links. And if it's a "go" this weekend I'll post a link to the wx station project site that has more details.

WildBlue Satellite Internet "WildBlue Value" is what we would get since it's more than enough for the wx data transfers. They say installation is "free" but for us it will probably cost ~$70.

Vantage Vue wireless weather station by Davis Instruments The Vantage Pro2 is their more expensive unit but does not give us any real advantages. We will also need the yagi antenna Davis p/n 7660. Details later.

WeatherPlug This replaces what normally would be a PC that receives the Vantage Vue wx data and streams it live to the WeatherUnderground website as well as other custom weather displays we can set up.

Weather Underground example personal weather station We will be able to configure our weather data to look like this. We could also display PWS "stickers" that show real-time wx on the SVSS website if Dudley wants to add it.

More soon...

Chris B.
Hi Chris,

Even one Yagi is borderline I think. I would put one at each end of the link. The company gives 1000 ft as "maximum range" I don't know how much, if any, fade margin is built into the power budget they use to get that number but Google Earth shows the path in question to be ~900 ft with one tree line in the way. Normally one would like 10 db or so of headroom for fade due to fog, rain, system degradation, etc. I have read that a "typical" loss for a single tree line is about 10 db at 900 MHz. Could be worse, could be better if you can sight some holes in the tree coverage. So, if there is no fade margin in the power budget (take that as worst case) we would need 20 db of total antenna gain to make a comfortable signal power budget. That means Yagi's are needed at both transmitter and receiver to get 20 db given the typical Yagi gain of 10 db.

Jon
Nov 18, 2010, 04:28 PM
Team Hello Kitty
SoaringDude's Avatar
Jon,

The 1000' limit you reference is between the stock wireless console and the stock sensor array. That spec presumes a clear line of sight and few trees, walls, etc. A single yagi (Davis p/n 7660) mounted on the roof of the clubhouse as compared with the indoor integral whip antenna will increase the effective range--conservatively, and through some trees--to 2500ft.

FWIW, it's not possible to retrofit any other type of antenna on the sensor array but then again we wouldn't want to do that. Worse case, if we can't do the yagi antenna then we can install a solar repeater (Davis p/n 7627) mid-way between the console and sensor array and accomplish the same thing. The yagi is a cleaner and more reliable approach.

Regarding fading due to fog and rain, the short distance and relatively low frequency in our setup makes that consideration a non-issue. You might be interested in this reference on the topic (see charts on page vii).

Chris B.
Last edited by SoaringDude; Nov 18, 2010 at 04:38 PM.
Nov 18, 2010, 09:39 PM
Registered User
Yes, scattering and attenuation by rain and fog is negligible at 900 MHz. What I was referring to was the increase in scattering and attenuation as water accumulates on tree leaves from rain and fog which is more significant. If one believes the 9 db attenuation by a dry tree that I have read then your single Yagi solution, owing to the Yagi 10 db gain, will result in effectively the same "range" as published and it should work OK if the company has built in some headroom into its power budget. However, again depending upon their headroom, the link could fail or become unreliable when the trees are wet.

Putting a Yagi at both ends of the link would likely insure operation in the rain. If the company has a generous amount of headroom included and the tree attenuation is not as bad as what I have read, then the link would work just fine. I guess all I am saying is it is possible that one Yagi is not enough for all possible situations. We need to experiment, but it would be prudent to have a backup plan should we find one Yagi is not enough. I agree that a repeater is not the ideal solution. Why can't we put a Yagi on both ends of the link? They are not that expensive.


Quote:
Originally Posted by SoaringDude
Jon,

The 1000' limit you reference is between the stock wireless console and the stock sensor array. That spec presumes a clear line of sight and few trees, walls, etc. A single yagi (Davis p/n 7660) mounted on the roof of the clubhouse as compared with the indoor integral whip antenna will increase the effective range--conservatively, and through some trees--to 2500ft.

FWIW, it's not possible to retrofit any other type of antenna on the sensor array but then again we wouldn't want to do that. Worse case, if we can't do the yagi antenna then we can install a solar repeater (Davis p/n 7627) mid-way between the console and sensor array and accomplish the same thing. The yagi is a cleaner and more reliable approach.

Regarding fading due to fog and rain, the short distance and relatively low frequency in our setup makes that consideration a non-issue. You might be interested in this reference on the topic (see charts on page vii).

Chris B.
Nov 19, 2010, 01:40 AM
Team Hello Kitty
SoaringDude's Avatar
Jon,

All good questions and topics to work through. Can I suggest we take this offline? I think that would be more efficient. I'll PM you my phone number--call me sometime Friday if you have time.

I have my fingers crossed that we get the go-ahead from the Bowmen club. If we don't this is all academic.

Chris B.
Nov 19, 2010, 02:07 AM
Team Hello Kitty
SoaringDude's Avatar
In the meantime I found this report (see Table 2-1) from the Univ of Texas that corroborates what Jon is saying. Film at 11...
Nov 20, 2010, 09:53 AM
Registered User
Chris,

OK

However I was occupied all day Friday and could not call.

Jon



Quote:
Originally Posted by SoaringDude
Jon,

All good questions and topics to work through. Can I suggest we take this offline? I think that would be more efficient. I'll PM you my phone number--call me sometime Friday if you have time.

I have my fingers crossed that we get the go-ahead from the Bowmen club. If we don't this is all academic.

Chris B.
Nov 20, 2010, 10:06 AM
Team Hello Kitty
SoaringDude's Avatar
I'm giving a presentation to the Yolo Bowmen today at 10am at their club meeting. Hopefully we will be able to answer all their questions and get their blessing soon. I'll keep everyone posted.

Afternoon update: Exciting news! The Yolo Bowmen have given us an enthusiastic thumbs up for our weather station project. You can now track the weather station project via the SVSS Weather Station Project site. If you have feedback or comments on any aspect of the project, you can provide it either in this forum thread or by adding comments directly to the project website pages (using your Google/Gmail account).

Chris B.
Last edited by SoaringDude; Nov 20, 2010 at 07:15 PM. Reason: Afternoon update
Nov 26, 2010, 11:10 PM
Team Hello Kitty
SoaringDude's Avatar

Post from Richard


(copied this post from Richard from main SVSS intro thread to here)
Chris,

A couple of questions / ideas on the weather station design.

1) If the installation of a yagi at the clubhouse is not sufficient in pulling in the signal from the sensor, is it possible to simply have a buried coax line running from the clubhouse to a location in the clear or closer to the sensor and then install a cemented pole in the ground and mount the yagi there instead? You might not even need a yagi at this point.

2) Instead of a stacked yagi configuration, how about just adding a receiver pre-amp instead?

3) If the Archery clubhouse is going to have WiFi, perhaps a WiFi base remote camera be added at a later time. I saw a remote pan and tilt Internet webcam at CostCo the other day for only around $180. Also, will the WiFi be reachable from the SVSS shade structure?

Richard
Nov 27, 2010, 12:31 AM
Registered User
Here's a link to an 18dbi 900 Mhz Yagi. Perhaps something like this or even better exists.

http://www.wlanparts.com/product/90E...AGI-18DBI.html

Or if you want to homebrew an antenna here's a construction article for a 9-10 db yagi:

http://www.ehow.com/how_7531213_buil...i-antenna.html
Last edited by KA6IPK; Nov 27, 2010 at 12:48 AM.
Nov 27, 2010, 01:39 AM
Team Hello Kitty
SoaringDude's Avatar
Quote:
Originally Posted by KA6IPK
Here's a link to an 18dbi 900 Mhz Yagi. Perhaps something like this or even better exists.

http://www.wlanparts.com/product/90E...AGI-18DBI.html

Or if you want to homebrew an antenna here's a construction article for a 9-10 db yagi:

http://www.ehow.com/how_7531213_buil...i-antenna.html
Great find on the 18dBi yagi, Richard. That's $37 cheaper than the one spec'ed now. Can't find a spec sheet for it, listing shows mfgr as "OEM."

Chris B.
Nov 27, 2010, 11:50 AM
Team Hello Kitty
SoaringDude's Avatar
Quote:
Originally Posted by KA6IPK
2) Instead of a stacked yagi configuration, how about just adding a receiver pre-amp instead?

Richard
Great idea. After doing a little research the best use of a receiver preamp in our setup would be to locate it right at the yagi antenna (i.e. on the mast) and use just enough preamp gain to compensate for coax line losses. That way the overall signal-to-noise ratio is not further degraded and you don't run the chance of overloading the Vantage Vue console receiver front end (they imply a signal max of -20dBm).

Spec-wise, the lower the noise figure the better. Assuming a 50 foot run of RG-6 coax, we would lose about 3db of signal. So a preamp could buy us back that loss. Most preamps I looked at have very high gains (>20dB) which will not help us out unless we use much longer coax runs. Want to suggest specific models?
Nov 27, 2010, 11:57 AM
Team Hello Kitty
SoaringDude's Avatar
Quote:
Originally Posted by KA6IPK
1) If the installation of a yagi at the clubhouse is not sufficient in pulling in the signal from the sensor, is it possible to simply have a buried coax line running from the clubhouse to a location in the clear or closer to the sensor and then install a cemented pole in the ground and mount the yagi there instead? You might not even need a yagi at this point.
Richard
Interesting idea. Here are a few trade-offs I see:

A. RG-6 satellite grade coax has 5.5dB loss per 100ft at 900mHz. So if we ran coax 1/3 way to the sensor unit (i.e. ~300 ft) and past most of the trees, we would lose 16dB of signal (almost the full gain of the yagi). So we would have 650 feet to go as if we were receiving with the standard whip antenna. Might work. We could pay more for lower-loss coax or use a preamp as you also suggested.

B. The second and perhaps bigger issue may be digging the trench itself. Would need an okay from the Yolo Bowmen and probably would need county permits too. If our initial tests show we need more gain, we can explore this or a variant thereof.

Chris B.


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