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OTA: The Big Trees Factor

21086 Views 55 Replies 20 Participants Last post by  stampeder
tigerbangs said:
Stampeder: get that 4228 and the 1111 up on the roof and quit your stalling!
Oh the irony! Here I am cheering on OTA converts, yet I can't enjoy it myself the way I'd like to! I am chomping at the bit to get those up and running but actually I've now done 2 test placements on the roof and the results were really awful due to the tall trees. I can't seem to find a sweet spot anywhere in the yard after dragging around my CM4228 on its mast, with my LG tuner with a 13" TV in tow. Also 4DTV_HD offered to come by with his spectrum analyzer to see if we can find one but I doubt that we would so I don't want to waste his time. I had to put my ugly little satellite dishes up on a 10' pole in my vegetable garden just to see the BEV sats.

:( My only choices are

1) put up a 60' tower
2) chainsaw massacre (illegal - the trees are protected, and we love them too)
3) move
4) climb that big tall fir tree and put all the gear up there (not!)

We'll see, but I tell ya its frustating, like having a Jacuzzi with no water connection. ;)
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robcreaser said:
One more choice would be to install a low noise amp. You didn't say in your test thread if you received low signal strength or no signal.
Thanks - my CM4228 runs through a Winegard AP8275 preamp so it has about the highest gain setup a person could get. Were you referring to that, or to a further amp in the chain? With the present setup most expected signals are too low for a lock.
Tom.F.1 said:
I just read my family Stampeders post about nowhere to mount the antenna. They voted for chopping down trees, but i like the 60ft tower idea.
Ooooooo.... them's fighting words around the Vancouver area! :) The relentless sprawl of suburban development is costing us more and more beautiful old firs and red cedars around here, and people have started to get really irate about tree chopping. We love our trees, so I just would not have the heart to cut them even if protecting them wasn't in a property covenant. I think we might even be leaning towards moving, but not because of my dear antennas! :D Nevertheless I've marked out other areas on maps out here that would get good reception. ;) Here are some photos of my tree predicament:
Trees as Antenna Masts

026163 said:
how would it work out if I wedged my CM4228 among the branches of a very tall tree in my yard
I investigated that sort of thing once before because I have a massive ~150 foot Douglas Fir on my property that stands above everything else for miles. My neighbourhood is also on a hill. Wow, the reception up there would be spectacular! Here's the problem:

No matter what the size of the tree, the ATSC digital TV standard is meant only for stationary reception and was never meant for moving antennas. A tree is a dynamic structure, even if it is completely dead, so by mounting even the best of antennas in one you are guaranteeing that with even a small amount of branch or trunk sway you will get minor pixelation and/or audio dropouts at the least, and complete dropouts in high winds at the worst.

Sorry to be the bearer of bad news. ;)
Grand Audio said:
I'm surrounded by 80' pine trees. With a lot of hickory and oak scattered amongst them. When the leaves and pine needles come back, I'll really be in trouble.
My world and welcome to it... :( Douglas fir, red cedar for year round attenuation, maple and birch for summer/autumn signal killing. Its an OTA nightmare here so I've had to take extreme measures short of getting out my old chainsaw and then getting fined/sued! :D
mclapp said:
Evergreen trees will really knock down a TV signal, I've seen many times when an antenna near the ground pointeing below the tree branches will work much better than one higher pointing into the bulk of the trees.
I can confirm that 100% - CM4228 at ground level below trees:

Massive trees on my property:
Thought about it. ;) 4 years ago i thought about putting them up on top of the Douglas Fir but the posts I gave mention why I didn't. Also a tree is a dynamic being, so ATSC digital locking would be constantly ruined by the motion in even a slight wind.

The red cedars are similar to sequoias in that the tops are very slender and not very solid. A guy in a nearby neighbourhood put his ham radio antenna up on one, but after a few wind storms it lay to rest so deeply entwined in the upper small branches that he had to leave it there. He has a metal tower and new antenna now.
True, but in moderate winds the flex of the tree goes down about 2 thirds its height, so the ATSC locking problem still exists. On analogue you get the visual equivalent of "wow and flutter" when the trees are moving. :)
Two or three times a year we get gale-force winds off the Pacific and the deadfall from out of those trees is awful. Occasionally we get a real whopper like the one that knocked down over a thousand such big trees all around Vancouver a couple of years ago.

You get some really nasty ones off the Atlantic, don't you?
300ohm said:
a gimbal mount mast may be the solution
A gimbal mount! (cranial noise generator goes into overdrive, core temperature rises)
Yep, I've looked at buying an 91-XG too for the great rejection but I'll be doing more testing for the time being. :)
kooguy since they're 100' away see the Antenna Tilt thread and give that idea some consideration.

Also the latest Generation 6 ATSC chipsets were designed to handle this sort of multipath interference better than previous versions, so that's a consideration for people in treed areas.

Check your local tree bylaws before cutting anything, even if they're on your own property. In my municipality there are certain "heritage trees" which cannot be topped or cut for any reason other than disease or imminent danger. I've heard that there are very strict tree-cutting bylaws in other cities too.
Elevation of Obstacle Calculator

Tom.F.1 said:
Trees aren't quite as bad as brick walls, but close.
Out here on Canada's Wet Coast the giant firs and cedars get waterlogged after a few days of rain and can be like a giant RF curtain! :D

Related to this topic, I found a handy calculator for estimating the height of obstructions based on your distance and angle from it:
Regarding the effect of leafy tree groves or forests on TV reception, this is a well known attenuation and/or multipath phenomena that particularly affects the UHF band. The effect on VHF-LO is basically nil, while FM Radio and VHF-HI seems to do okay through leafy areas.

Rain, mist, fog, low cloud, sleet, and heavy snowfall are other environmental TV signal attenuators. If you have a leafy area between your antenna and a fringe to deepest fringe station you have a double whammy if the weather gets really wet. Here on Canada's "Wet Coast" it is readily seen as such weather patterns change. Quebec's Eastern Townships see quite a change when the trees lose their leaves for the winter.
Late Spring in most of Canada this year

It has been a relatively late spring here on BC's south coast and much of Canada has had a soggy, gray spring so far, but now that the weather is getting warmer and the skies brighter the deciduous trees (maple, ash, beech, poplar, oak, elm, birch, etc.) are starting to really fill out, some blossoming.

As noted earlier in this thread UHF antennas are highly affected by trees, while VHF-LO are not, and VHF-HI usually are not.

Here on the West Coast the giant cedars and firs are in a growth phase too. My UHF 4-Bay bowtie reflector pointed at Mount Seymour is being touched by cedar boughs that were about a meter away last year! I have to get up there with my loppers today and cut them away again.
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