Reception problem on one channel

john262 · 4-Jun-2015, 6:16 AM

Hi, I have a Winegard Freevision antenna mounted on the platform that my satellite dish used to be on before I took it down. I have it pointed at some transmitters located LOS 4.7 miles away. I know it's pointed in the right direction because I can actually see the transmitting towers from my roof so it was easy to point the antenna. I am not using a preamp or a distribution amp. I have it connected to a passive two-way splitter that feeds two TV's. Judging from my TVFool report I didn't think I needed any kind of amp.

Anyway, I get very good reception on every one of the channels that transmit 4.7 miles from my house but one. It's channel 17 or virtual channel 11. It keeps pixelating on me. Sometimes it will be good for maybe an hour or two at a time, then suddenly it becomes virtually unwatchable for a while, then it gets good again. This happens during all weather conditions.

The thing I don't understand is this channel has better signal strength than several other channels that don't pixelate, according to my TV's signal strength meter. Channel 17 usually has a signal strength reading of 68. But some of the other channels go as low as the low 50's yet they never break up on me like 17 does. I can be sitting watching channel 17 and suddenly it will start to break up on me and I will check the signal strength meter and it's 68. Then I switch over to channel 36 and it is at 52 yet it's coming in just fine.

So I'm wondering if anyone has an idea what's going on and if there is anything I can do about it. All of these transmitters that I get except for one are translators rebroadcasting distant stations.

I'm wondering if perhaps this isn't a problem with my antenna and maybe it's a technical problem with the channel 17 transmitter or perhaps with the fiber optic cable that feeds it. Thanks for your help.

John

ADTech · 4-Jun-2015, 10:07 AM

Move the antenna up and down the mast and retest.

If necessary, relocate the antenna elsewhere.

john262 · 4-Jun-2015, 10:49 AM

Quote:

Originally Posted by ADTech

Move the antenna up and down the mast and retest.

If necessary, relocate the antenna elsewhere.

Thanks. So you think that even with the strong signal according to my TV's signal strength meter that means that it's a problem with the antenna's location? It's a direct line of sight already with no obstructions such as trees and buildings in the way at all. And why would it be affecting only one channel? According to the FCC's database all of the UHF translators I am pointing at are the same power, 1 kw. So why would one 1 kw transmitter come in OK while the other doesn't when they are both in the exact same location? Just wondering. Thanks.

ADTech · 4-Jun-2015, 12:06 PM

It is a mistake to think that all signals from a given origin will be homogenous at some other arbitrary point in space at some distance. It just doesn't work that way. Your antenna may be in a spot that is getting an odd-ball reflection that just happens to coincide with that channel's operating frequency.

Try moving the antenna and re-testing. It's a simple step and doesn't cost anything but some time and work. That will tell you if it's a signal path anomaly or some problem with the origin.

It's also possible that there's a kink or other fault in your cabling or splitter that's causing a "suck-out" at a particular frequency. You'd have to run a temporary coax to test that idea.

You may well need to do some detective work to find out if it's an issue with your receiving system or if it's on the other end. Good luck.

john262 · 4-Jun-2015, 1:35 PM

Thanks for your help. I will try to move the antenna later today but it might be a while before I know if it helps because as I said sometimes it is good for several hours before it starts to go out on me again. For instance I just tried it now and it's great whereas last night it was virtually unwatchable.

And I take it that my TV's signal strength meter isn't reliable either because as I said it shows this channel with a stronger signal than others that I am having no problems with.

Tim · 4-Jun-2015, 2:18 PM

If those things don't help, you might also try contacting the station engineer. Perhaps they had an equipment failure and they are operating at lower power temporarily.

ADTech · 4-Jun-2015, 2:37 PM

Do continue to monitor the "signal meter" when you're having issues. The so-called meters usually are not giving an indication of actual strength (power) of the signal, but rather are an indication of the ability to decode the digital data stream that has been transmitted.

If you see the "meter" fluctuating rapidly in time with the disruptions, that's almost always an indication of interference of some sort. Multi-path is, by far, the most common type encountered. Small, not very directional antennas like the one you have are most susceptible to this issue.

rabbit73 · 4-Jun-2015, 6:20 PM

I wanted to look at your FM signals to see if they might be causing interference to your TV reception. I made an estimate of your location for a tvfool report that seemed to match yours:
http://www.tvfool.com/?option=com_wr...f1f071e1da6fc9

and I used that location to generate an FM FOOL report. See the attachment.

Quote:

Multi-path is, by far, the most common type encountered. Small, not very directional antennas like the one you have are most susceptible to this issue.

I agree with ADTech. A more directional antenna might help.

Quote:

I have it pointed at some transmitters located LOS 4.7 miles away. I know it's pointed in the right direction because I can actually see the transmitting towers from my roof

Channel 17 is not on that tower, it's on a tower at 5.0 miles away at a different azimuth. With an antenna that isn't very directional, it probably wouldn't make any difference, but what could it hurt to rotate it a little to the right? You could try a more directional antenna like the RCA ANT751.

There is a good chance that you are getting a reflected signal of CH 17 off the ridge at the rear of the antenna that is causing interference to the direct signal. An antenna with a good Front-to-Back ratio might help.

There is also the possibility of FM interference. Your strongest FM signal is KRJC with a strength of -16.8 dBm. It wouldn't cost much to insert an FM filter in the RG6 coax line as a test, but it would knock out real CH 6.
http://www.mcmelectronics.com/produc...-FM-88-/33-341
https://www.antennasdirect.com/store...on_filter.html

Is your coax grounded?

The coax shield should be grounded with a grounding block that is connected to the house electrical system ground with 10 gauge copper wire for electrical safety and to reject interference. For further compliance with the electrical code (NEC), the mast should also be grounded in a similar manner to drain any buildup of static charge, but the system will not survive a direct strike.

john262 · 4-Jun-2015, 6:38 PM

Thanks for all of your help everybody. I finally got a call back from the Elko TV District and they confirmed that there are some technical problems. I also checked with my neighbor who has cable and he said that the cable system has been running a notice on that channel telling the viewers that that there are technical problems. Apparently they get their signal with an antenna just like I do.

Anyway, it's not my antenna. That explains why it used to work before then for no apparent reason I started to have problems.

ADTech · 4-Jun-2015, 7:36 PM

Okay, that's good news that explains it.

Good luck!

john262 · 4-Jun-2015, 8:31 PM

Thank you for that very detailed reply. Yes the coax is grounded and the platform that it is attached to is grounded as well.

rabbit73 · 6-Jun-2015, 5:10 PM

Quote:

Anyway, it's not my antenna. That explains why it used to work before then for no apparent reason I started to have problems.

That explains why you were having a problem, but it doesn't explain why they are having a problem.

john262 · 7-Jun-2015, 8:32 PM

Quote:

Originally Posted by rabbit73

That explains why you were having a problem, but it doesn't explain why they are having a problem.

They didn't explain exactly what the problem was but I have been asking around and apparently they are notorious for this sort of thing. And I think that generally speaking remote translators like this are not maintained as well as a station's main transmitter.