Author Topic: WS-2902a sensor antenna and snow  (Read 686 times)

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Offline madkiwi

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WS-2902a sensor antenna and snow
« on: December 05, 2018, 02:23:29 PM »
Ambient Tech Support was nice enough to send me a new sensor array after I asked about the blackout when we had a snow event. Apparently that was before they talked to their engineers, because in a followup email they told me the array may be functioning perfectly but the snow/ice buildup will block transmissions and a new sensor array won't change that.

Talked with my brother (electrical engineer who works in the semiconductor fab industry) and he pointed out that water only a few thousandths of an inch will block 915 MHz radio waves.

He was visiting this week and on examining the array he figured the protuberance on top next to the UV sensor is the antenna (I didn't allow him to take it apart though) and if snow was to pile up on it that would be enough to disrupt the transmissions. In his opinion that was a poor design choice, he thinks modifying the antenna with the antenna extending downwards would be best for our climate.

Because I wasn't letting him dismantle the unit (or the new one) we have not figured out how easy this would be, although one thing was noted- a 1/4 wavelength antenna would be 78 mm long, that bump on the array is less than 1/2 of that. So our guess is that the antenna is the correct length but only part of it extended beyond the body of the array.

I have to decide if I want to make a modification, at least I have a "spare" array to tinker with. Could be as simple as drilling a small hole on the underside and reorienting the antenna downwards, then sealing around the hole with silicone.

Thoughts? Anyone done this already?
WS-2902A WU:KMTFLRE23
WS-2813 WU:KMTMISS015


Offline DoctorKnow

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Re: WS-2902a sensor antenna and snow
« Reply #2 on: December 05, 2018, 03:59:46 PM »
The acurite 5 in 1 antenna is installed pointing down. I guess this is why...

Offline davefr

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Re: WS-2902a sensor antenna and snow
« Reply #3 on: December 06, 2018, 01:21:35 PM »
I thought someone here was experimenting with adding an external Yagi antenna to the sensor.  Curious if anything came of it?

Offline StephenR0

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Re: WS-2902a sensor antenna and snow
« Reply #4 on: December 07, 2018, 11:40:33 AM »
Here is the FCC site for the WS-2902a sensor array, the WH65B.

https://fccid.io/WA5WH65BV1

The internal pictures are here.

https://fccid.io/WA5WH65BV1/Internal-Photos/Internal-Photos-3627166

In the second picture, you can see the antenna.  It looks to me like a very common quarter wave antenna curled in a coil to minimize length.  I haven't taken mine apart either.  Like your brother, I had supposed that the thing on the top was where the antenna went, although I don't know for sure.

Offline kbellis

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Re: WS-2902a sensor antenna and snow
« Reply #5 on: December 19, 2018, 09:25:39 AM »
Ambient Tech Support was nice enough to send me a new sensor array after I asked about the blackout when we had a snow event.
That was nice! How was the overall experience of getting an RMA, swap completed, shipped, etc. go?


He was visiting this week and on examining the array he figured the protuberance on top next to the UV sensor is the antenna (I didn't allow him to take it apart though) and if snow was to pile up on it that would be enough to disrupt the transmissions. In his opinion that was a poor design choice, he thinks modifying the antenna with the antenna extending downwards would be best for our climate.
Good call! Even if it wasn't in a snowy clime, having the antenna underneath makes sense as the receiver (console) isn't likely to be positioned above the outdoor array.




I have to decide if I want to make a modification, at least I have a "spare" array to tinker with. Could be as simple as drilling a small hole on the underside and reorienting the antenna downwards, then sealing around the hole with silicone.
Doesn't sound so simple to me, particularly after glancing at the PCB. Instead, I'd think about trying to make a little rigid hoody for it, but it would need to be shaped not only for the asymmetrical aspects of the array arm, but also shaped to face the receiver's position; e.g. directional towards the southeast. Keep the height of the hoody no higher than the neighboring UV sensor.

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Offline kbellis

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Re: WS-2902a sensor antenna and snow
« Reply #6 on: December 19, 2018, 09:31:10 AM »
Here is the FCC site for the WS-2902a sensor array, the WH65B.

https://fccid.io/WA5WH65BV1

The internal pictures are here.

https://fccid.io/WA5WH65BV1/Internal-Photos/Internal-Photos-3627166

In the second picture, you can see the antenna.  It looks to me like a very common quarter wave antenna curled in a coil to minimize length.  I haven't taken mine apart either.  Like your brother, I had supposed that the thing on the top was where the antenna went, although I don't know for sure.

Brilliant! How did you find this?
Is there another set of photos and documentation for the receiver (console)?
And thanks for posting!!

Offline StephenR0

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Re: WS-2902a sensor antenna and snow
« Reply #7 on: December 19, 2018, 09:52:19 AM »
The FCC public database turned up when I was researching using an SDR to get data from the sensor array.  Here's the page for all the Fine Offset products.

https://fccid.io/WA5

The page for the WS-2902 console is here.

https://fccid.io/WA5WH2902

There's also some interesting things in the other pages.  :-)

Offline kbellis

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Re: WS-2902a sensor antenna and snow
« Reply #8 on: December 19, 2018, 10:06:45 AM »
Fantastic! Thanks Stephen.

Offline danoh

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Re: WS-2902a sensor antenna and snow
« Reply #9 on: December 31, 2018, 02:24:53 PM »
Have you tried to spray the top side of the sensor array with silicone?  Maybe the ice and snow won't build up on it.

Offline kbellis

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Re: WS-2902a sensor antenna and snow
« Reply #10 on: December 31, 2018, 02:31:05 PM »
Yes, but we've only had one snow event since Christmas, a wet one that turned into rain.
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Also, should anybody else care, I photographed before and after application of the DuPont product which slightly dull the high gloss finish of the WS-2902A - I'll be happy to post those photos if asked.

Kind regards and Happy New Year!

Kelly

Offline kbellis

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Re: WS-2902a sensor antenna and snow
« Reply #11 on: January 01, 2019, 04:11:52 PM »
Have you tried to spray the top side of the sensor array with silicone?  Maybe the ice and snow won't build up on it.
Maybe worth noting, the DuPont Snow & Ice Repellent is a Teflon spray, not silicone, and works well on other things like snow blower chutes and snow shovels.

Offline MikeWest

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Re: WS-2902a sensor antenna and snow
« Reply #12 on: January 11, 2019, 03:13:32 PM »
Last winter I had snow on my 2902 array that was deeper than the cups were tall.  I never had a drop out of temps, obviously the solar and wind sensors were not detecting anything but I never lost comms with the array.

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« Last Edit: January 11, 2019, 03:16:30 PM by MikeWest »
So many trees in NJ!


 

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