OTA: The Big Trees Factor

21086 Views 55 Replies 20 Participants Last post by stampeder, May 23, 2011

stampeder

Discussion Starter · Jun 25, 2005 (Edited)

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.

21 - 40 of 56 Posts

Grand Audio

· #21 · Mar 24, 2009

300ohm said:
But keep in mind, thats more wind load, and more places for ice to form.

Don't have to worry about the ice down here, but get plenty of wind...hurricanes and tornados...more often than the ice.

If I can get this antenna to work consistantly, which it already outdoes the Terk TV44, I'll make a twin and make a 4228 out of it...lol.

Grand Audio

· #22 · Mar 24, 2009

Here's a screen capture off of google earth. I have a mobile home right under the trees below the pin cushion. The antenna is in center of the bare spot.

See less See more

stampeder

Discussion Starter · #23 · Mar 24, 2009

300ohm said:
a gimbal mount mast may be the solution

A gimbal mount! (cranial noise generator goes into overdrive, core temperature rises)

300ohm

· #24 · Mar 24, 2009

Looks like you have some chain sawing to do, heh.

hoopitup2000

· #25 · Mar 25, 2009 (Edited)

Stampeder,

With all those trees you are a prime candidate for multipath. I have numerous oak and maple trees at close range with extreme levels of mutipath. I tried the 4228 and it performed miserably, even with plenty of signal strength. I then tried the 91-XG and now reception is excellent. I see no difference in reception regardless of whether or not the trees have leaves on them.

Have you ever tried a yagi style antenna for UHF?

stampeder

Discussion Starter · #26 · Mar 25, 2009

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.

300ohm

· #27 · Mar 26, 2009

With all those trees you are a prime candidate for multipath.

Ive always thought along those lines too. The signal not only being blocked but bounced too.

A gimbal mount! (cranial noise generator goes into overdrive, core temperature rises

Grab a cold homebrew, heh.

balm

· #28 · Jun 24, 2009

trees on lake

300ohm,

I tried to understand the Holl_Ands links re. the effect of trees, but im not clear whether, in theory at least, it is better to have the antenna relatively close up to any interfering tree, or try for the furthest point away, given that there is no possibility to get the height to clear the tree at either position.

my thinking is the closer you are to the tree, the closer you are to any signal which is coming in relatively uninterrupted in the thinner parts of the tree, however the overall area of blockage would be larger.

On the other hand the further you are from the tree, the more chance the tree has had to distort the signal, however, the overall area of blockage becomes smaller

does that maky any sense, or should I just CUT DOWN all the trees!

balm

· #29 · Jun 29, 2009 (Edited by Moderator)

BBC Document on Tree Interference

for those interested, but somewhat outdated

http://www.bbc.co.uk/reception/info/pdf/trees_factsheet.pdf

kooguy

· #30 · Jun 29, 2009

At one point, I had a CM4221HD (15' off ground) point direct to some large maple trees about 100' away. After some long term testing, I find that the my signal reception is very much degraded consistently whenever there is wind blowing around.

balm

· #31 · Jun 29, 2009

yes the wind which causes the leaves to change positions, which in turn cause the diffracted waves, and reflected waves (if any), to change position (constantly), thereby by creating alternating weak signal spots, and stronger spots

oh well, at least there's no decision, nothing we can do about it, short of cutting all the trees (if there on your property of course!)

stampeder

Discussion Starter · #32 · Jun 29, 2009

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.

byebye_cable

· #33 · Jun 10, 2010

Any takers on how a single line of deciduous trees 50 meters away would affect me? They are very tall, no possibility of getting above them. At least they are not conifers.

Is 50 meters so far that the effect is minimized?

Tom.F.1

· #34 · Jun 11, 2010

byebye_cable said:
Any takers on how a single line of deciduous trees 50 meters away would affect me? They are very tall, no possibility of getting above them. At least they are not conifers.

Is 50 meters so far that the effect is minimized?

I installed a setup recently in Burlington for a guy with trees about 1/2 km away.
Two DB-8 antennas with 7777 preamp on a 8 ft mast, tripod on peak of roof on a very tall house.
No matter how we treid, we could not get all buffalo stations at once. Fox just wasn't there.
Same day, Install one DB-8 with 7777 in Erin, north of halton hills. Perfect reception of all buf/tor/ham. No trees.
Same two DB8 & 7777 setup on very tall chimney in Mississaga with trees. I told them it wouldn't work well, but they wanted to go ahead anyway. Got all stations except for NBC & CBS.
Trees aren't quite as bad as brick walls, but close.

stampeder

Discussion Starter · #35 · Jun 11, 2010

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!

Related to this topic, I found a handy calculator for estimating the height of obstructions based on your distance and angle from it:

http://www.satellite-calculations.com/Satellite/Elevation.htm

recneps77

· #36 · Jun 17, 2010

The 'big tree effect' is killing me right now.

There are very high winds and the large trees blocking my view of TO are waving like crazy. Every gust of wind drops the SNR so much that I get some dropouts for a second or two

It's only on City, though. The rest of TO is relatively stable.

This is the second time in ~3 years that this has been an issue, though, so not a huge deal.

Buffalo is extremely strong, though

byebye_cable

· #37 · Aug 23, 2010 (Edited)

Back to my single line of trees about 50 yards distant. The webpage below (I love this site) basically tells me to ANGLE my UHF Antenna so that it's pointing to the tops of the trees (about 5 to 10 degrees up in my case).

http://www.hdtvprimer.com/ANTENNAS/siting.html

Do the resident experts agree with this?

Unfortunately MCE isn't very precise when montoring signal quality, so it's hard for me to test this. I have very rare dropouts when it's windy.

majortom

· #38 · Aug 23, 2010

Unfortunately MCE isn't very precise when montoring signal quality, so it's hard for me to test this.

Sounds like ur using a PC Tuner of some sort? If so which one?
Try downloading the lite version (free) of TsReader, you should be able to get
a usable relative Signal Quality measurement from it (all cards are a lil different).

http://www.tsreader.com/tsreader/index.html

byebye_cable

· #39 · Aug 23, 2010

It's an HVR 1600. I'm allergic to installing anything on my MCE because I don't want to mess it up - however - that shoulds good, I'll take a look at it.

jgconnor

· #40 · Aug 23, 2010

Here in south Burlington, I had to move my Toronto facing antenna to the other end of my house to avoid facing into a line of white pines that prevented me from getting all the Toronto stations at once.

I still get occasional breakup on CFTO but hope that will improve once they increase the power.

My Buffalo antenna (70 feet away from the Toronto one) points at a hole in a large maple tree in my neighbour's yard. The only channel that is less reliable than I would like is CBS (virtual channel 4) which is hit or miss during the day, but much better at night.

BTW both antennas are CM4221HDs (hacked) and fed into their own CM7777.
They are joined and split inside the house to feed three tuners. It probably shouldn't work, but it does!

21 - 40 of 56 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.