Rception interference from traffic

[iaskalottaquestions]

I'm getting a lot of pixellation and signal loss from my OTA antenna whenever traffic goes by on the street; it seems to be worse with larger vehicles and happens mostly on one channel. At certain times of day, the traffic makes it unwatchable.

The antenna is roof mounted, 32' off the ground and oriented corectly toward the broadcast transmitters, which are about 20 miles away at 243°, set with a compass. RF cable is run from the antenna to the TV.

In looking around a bit, I've seen a couple suggestions. One, less practical for me, is to raise the antenna higher. Another is to point the antenna up at an angle higher toward the sky. For that, I'd need to make an adapter for the top of the mast.

Any thoughts on this?

Current antenna:





TV Fool report link:

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3de6a4c329c4fe6a

Sorry, couldn't find a way to edit spelling in title of thread.

 

[Fringe Reception]

iask,

Which channel is most affected by traffic? I relation to the transmitters @ 243 degrees, where is the 'offending' street (compass directions)? Please advise.

You could try lowering your antenna a foot at a time to see if your reception improves or move it to different locations on your roof and test it at a variety of heights.

Jim

 

[Fringe Reception]

iask,

Which channel is most affected by traffic? In relation to the transmitters @ 243 degrees, where is the 'offending' street (compass directions)? Please advise.

You could try lowering your antenna a foot at a time to see if your reception improves or move it to different locations on your roof and test it at a variety of heights.

Jim

 

[MrPogi]

Is your problem mostly channel 6 CBS? It's your only VHF-low band channel and VHF lo is susceptible to EMF noise.
I'd try moving the antenna up/down and N/S/E/W. But first I'd try moving the compass direction a few degrees. Moving from 243 by +/- 15 or so degrees may be just enough to attenuate the traffic noise.

 

[iaskalottaquestions]

Sorry it has taken me so long to reply, I've been having a LOT of trouble with the forum no matter what browser I use. But anyway, here I am & thanks for the responses.

My most troublesome channel is channel 18 NBC; followed by 6 CBS, with a bit less trouble.

The street with the traffic is in front of the antenna (reception end) and runs north-south.

I mounted the antenna as high as I could because there are also a couple trees in front of the antenna by the street that are (guessing) about 15-20' higher than the antenna.

 

[Fringe Reception]

iask,

Sorry for the issues accessing the Forum: the last software update has proven to be unstable and the vBulletin gurus have yet to resolve the issues.

As Mr Pogi mentioned above, Channel-6 is Low-Band VHF station which is far more susceptible to interference from electrical 'noise' sources such as HVAC fan motors, fluorescent light ballasts, some LED light bulbs, street lights (?) and high-voltage automotive ignition systems. Plus, your antenna is not designed to receive low-band VHF.

Channel-18 is located 120 degrees away from where your antenna is currently pointing, which likely explains your unstable reception. It likely would stabilize if you re-aimed your antenna but other channels would probably vanish.

First, I would try what we mentioned above: the physical location of your existing antenna may be in the 'wrong' place. Try it higher AND lower, then move it to other locations and try it at a variety of heights. That may be the key. DO NOT rescan your tuner because it already 'knows' the channels you want to receive.

If not successful, the next step would be to add a dedicated antenna for Channel-18 and use a 2-way switch to select it or your existing antenna: it may receive additional channels from 136 degrees. Option: rather than using a switch to select different antennas, there is a new device called a Jointenna which (allegedly) allows single-channel antennas to be 'joined' to an existing antenna system. No Forum members have experience with this yet, so we do not know how well they work.

Regarding Channel-6, do you remember the flat-wire dipole antennas that were supplied with FM Stereo tuners in the 1960s and 70s? They were about 7 feet wide, clear plastic and often put on ceilings or walls using thumb tacks. You could make a similar antenna (somewhat wider), test it and if it works combine it with either of the above antennas using a UHF/Low-Band/Signal/Joiner.

Please keep us posted.

Jim and the DTVUSA Forum Staff

 

[iaskalottaquestions]

Thanks for the suggestions, looks like a little roof-time is in my future.

 

[Fringe Reception]

iask .........

Yes, but (again) do NOT rescan your tuner. Work from what it already 'knows' (and has in its memory) ...

Jim

 

[iaskalottaquestions]

Thanks.

 

[iaskalottaquestions]

It's been several months now, but yesterday was the first time I have been up on the roof.

I lowered the antenna about a foot, and reoriented it to about 220°. The results were an improvement in the pixellation on channel 18 (WNYT), but a weaker signal on channel 6, to the point of sometimes losing the signal.

In regard to Fringe Reception's comment above about the old FM atnennas, I have an old FM antenna that looks like this:


Would it help the ch. 6 signal to orient that for that channel's reception and use a combiner to run it to the TV cable?

I suspect my problem is not only the traffic, but the trees in the signal path.

 

[Fringe Reception]

Iask,

In your first post you indicated your High-band VHF / UHF combination antenna is already aimed toward WRGB-6 and WXXA-7. You can add a dedicated high-band VHF to your existing coax using an inexpensive UVSJ (UHF/VHF/Signal/Joiner) which isolates the antennas so they don't compete against each other. That said, I think your omni-directional (compromised) FM antenna is a poor choice, however, it is certainly worth a try.

We rarely recommend omni antennas because they receive signals from all directions and if you recall 'scratchy-sounding' FM Stereo, that may be your result for channels 6 and 7 -- except -- digital tuners are confused by damaged signals. Back to TV, recall ghost on your screen in the analog days where a horse with a saddle has two saddle horns and two tails caused by the reception of a second identical signal arriving at your antenna after being reflected from a mountain or a large building: digital tuners cannot work with a doubled or tripled data stream.

My thought was to use an FM dipole (twin-lead dipole) like this for testing:
http://www.acehardware.com/product/...MI6u34tdrZ1gIVm7XACh0FFAkeEAQYAiABEgIM9PD_BwE

The best answer would probably be to combine a dedicated (directional) high-band VHF Yagi like this for channel 6 and channel 7: http://www.newark.com/stellar-labs/30-2475/fringe-directional-antenna-vhf/dp/48Y8141

Antenna height is more critical at lower frequencies (channels) and you may have a perfect signal at roof level, but little or poor signal 3 feet above, and a clean signal may again be present at 6 feet above your rooftop. "Walk" the antenna around until you find the best location before you select a permanent installation location.

Another possible issue is your close proximity to the channel 6 transmitter: you may have to add a signal attenuator to reduce the amount of energy your antenna receives, but we can deal with that later. I hope this helps.

Jim

 

[iaskalottaquestions]

Thanks. I did remember the old plastic/wire dipoles, in fact I think I have one somewhere. I thought the one I posted served the same purpose & didn't know that they are different (have one of those too, seems I never throw stuff out!).

Thanks for the informative post, I'll have to do some more experimenting & will get back afterwards.

 

[Fringe Reception]

iask,

Your 'S' shaped FM antenna is (in theory) omni-directional, but a folded dipole is bi-directional and it ignores signals coming to it from its sides. If you are experiencing multipath reception, the dipole should be a superior antenna.

Jim

 

[iaskalottaquestions]

I really appreciate all the assistance.

I got up on the roof and lowered the antenna about a foot and adjusted the direction again. That helped a lot with the pixellation from passing traffic, I'd say it's about 95% better, at least so it's not very disruptive at all when we watch. And it happens mostly in the early evening for some reason. Weather conditions affect its severity too, and traffic is fairly variable. So I think it's about as good as we'll get it considering our trees.

Thanks much.

 

[Fringe Reception]

iask,

My guess is you have found the ideal height, so next Spring when the weather improves consider moving it a foot or two sideways: that might be the trick to perfect your setup.

Jim

 

[iaskalottaquestions]

Thanks again.

 

[iaskalottaquestions]

I know this thread is old as dirt, but I think I've finally solved my problem by adding a smaller dedicated antenna aimed at 136° for the transmitter about 4 miles away for real channel 18 and using a signal combiner. My problem had gotten worse with thick leaves on the trees and summer weather, so I decided to try this. So far there has been no pixellation and I will continue to monitor it.

The larger top antenna is pointed at 243°, and the smaller, lower one at 136°, guided by the TVFool recommendations. TVFool charts

 

[Fringe Reception]

Iask,

Good job and congratulations!

Jim