Trees, wind & signal breakup

[rmccolman]

Hi Guys,

We live in a somewhat challenging reception area, with the bulk of transmitters around 40 or more miles away. Only 2 transmitters are rated "Good" on Rabbitears.info, with 11 rated "Fair." (The remainder, which we don't try to watch, are rated "Poor" or "Bad.") On TVFool, none of the transmitters are listed as LOS; everything within 50 or so miles is listed as either 1Edge or 2Edge (most 2Edge). However, the terrain and distance aren't the real problem for us, as we have a rotor-mounted Televes DATBOSS Mix LR UHF VHF antenna with supplied preamp roughly 25 feet off the ground.

When winds are reasonably calm -- 0-15 (or so) MPH -- we don't have much signal breakup at all, despite shooting through a lot of trees that are probably at least 50-60 feet tall. But when the winds are 20+ MPH during the warmer months when leaves are on the trees, the signal breakup can be considerable on some stations, with substantial bursts of breakup every few seconds on several stations, interlaced with stable signal for a few seconds in-between.

My thought is that the only way to remedy this would be to mount the antenna on a tower at least 40 feet high, otherwise simply live with the breakups on windy days. (We don't get a huge number of windy days here, but we do get some.) The Televes performs far better than any other antenna we've had, but significant wind and leafy trees can prove a challenge even for it. Do note that we use the rotor to zero in on the stations we're watching (transmitters are clustered in multiple directions), so we are optimizing antenna aim.

Any thoughts on a solution besides jacking the antenna up considerably higher than we have it now?

I figure that a tower mounting is likely the only solution, but I thought I'd see if anyone has any other bright ideas.

Thanks,

Richard

 

[TheKrell]

Any thoughts on a solution besides jacking the antenna up considerably higher than we have it now?

I am having a hard time understanding how the wind blowing the trees can cause this breakup. Surely the wind alone can't do that, unless of course you have a loose connection. Does this breakup happen when there are no leaves on the trees?

 

[rmccolman]

I am having a hard time understanding how the wind blowing the trees can cause this breakup. Surely the wind alone can't do that, unless of course you have a loose connection. Does this breakup happen when there are no leaves on the trees?

Little to no signal breakup when the winds are calm. As I mentioned in my original post, we get very little of this effect on windy days in the cold weather months when there are few leaves on the trees. As was mentioned in the YouTube video referenced below, the phenomenon affects UHF much more than VHF, and is more prevalent the higher the frequency.

For more info on this effect, check out the links below:

Why does the wind adversely affect over-the-air television transmission?

Why does the wind adversely affect over-the-air television transmission? Continue reading →

wxguys.ssec.wisc.edu

Richard

 

[rmccolman]

And the same as was mentioned in the video, our VHF stations aren't affected by this.

Richard

 

[TheKrell]

And the same as was mentioned in the video, our VHF stations aren't affected by this.

Richard

And the link says "multipath". OK, I stand corrected. I would still check your connections anyhow, if you haven't done so already.

And I just lost a white pine tree to high winds! Fortunately it's lying in my front yard and not on the house.

 

[Tvland1]

I get a little bit of signal loss on windy days with my Televes setup on the camper due to movement of the telescopic mast.. your antenna is probably moving because of the rotor shaking back and forth.. ALL of the rotors I've had except the Yaesu have movement.

I like the way he says at first the station's are about 70 miles as the crow flys then says he can see the transmitter with binoculars 20 miles away....

 

[rabbit73]

But when the winds are 20+ MPH during the warmer months when leaves are on the trees, the signal breakup can be considerable on some stations, with substantial bursts of breakup every few seconds on several stations, interlaced with stable signal for a few seconds in-between.

Hello, Richard

The trees are probably the main cause of the problem; it's a form of multipath. But you should check for other causes.

The tree outside my window certainly messes with my signals on a windy day.

Video of signal during heavy winds
Download and view now (I use VLC Media Player)
CH16TreeInPath4.mp4

Download now, view later
https://www.dropbox.com/s/ig3va499k237ayu/CH16TreeInPath4.mp4?dl=1

The video was made with the GE34792 antenna; the GE29884 does better.

My thought is that the only way to remedy this would be to mount the antenna on a tower at least 40 feet high, otherwise simply live with the breakups on windy days. (We don't get a huge number of windy days here, but we do get some.)

Mounting it above the trees would give the best reception.

Any thoughts on a solution besides jacking the antenna up considerably higher than we have it now?

I figure that a tower mounting is likely the only solution, but I thought I'd see if anyone has any other bright ideas.

It is possible that ATSC 3.0 signals will be able to handle multipath better.

 

[rmccolman]

Interesting thoughts, guys.

As an experiment, I could go up on the roof on a calm wind day and try shaking the short mast section above the rotor to see if I can induce signal breakups on UHF channels.

Checking the coax connections is always a good idea. In this case, however, I'm a bit skeptical that loose connections are a contributor, since while I was getting some signal breakup on UHF channels with wind, the VHF stations at the same time were exhibiting little to no breakup.

Thanks all,

Richard