Increasing Interference above 600 MHz - AVS Forum
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post #1 of 9 Old 03-12-2011, 09:39 PM - Thread Starter
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TWC digital cable with Cisco 8640 stb. I'm having signal strength/interference issues with my HD channels starting at about 600 MHz (by "issues", I mean that channels at or above this frequency are unwatchable). For channels at the lower end of the problem range, the QAM tuner will often get a lock, but the signal strength is only -19 to -20db, resulting in a severely pixilated picture and audio that cuts in & out. By ~650 MHz, the tuner often can't lock on to the signal at all. The HD on-demand channels display a "temporarily unavailable" message.

If I remove the STB & connect to my TV's tuner, I can sometimes receive the local HD signals, but many of the analog channels show a lot of "bleed" interference.

From the service entrance, the feed (all cables are RG-6) enters a 2-way 5-1000 MHz splitter: one output goes to the cable modem, the other to the STB. I've replaced every interior cable, and I've even connected the STB directly to the cable entering the house: no change.

TWC techs have been here 5 times, and each time they've checked the signal strength (not sure what frequency, as I've only recently figured out the pattern) and declared it satisfactory.

The big kicker is that the problem is intermittent. Even though it's happening more & more frequently, the signals always seem to be no worse than -18db when the tech is here, which is just strong enough to produce clear HD picture & sound.

I've tried 4 different STBs (2 8300s and 2 8640s) and all have the issue. The problem SEEMS to be worse during prime time, but that may just be because that's when my wife is trying to watch her shows. If I reboot the STB, it will frequently display "E-13" as it tries to download the info it needs, and will then reboot itself every 20-30 minutes until it is successful. Lately, this has taken over 24 hours after the reboot before the system is usable again.

We live in an old neighborhood, so all of the lines are overhead. The problems seem worse during bad weather, but the techs each claim to have visually inspected the line from the pole, and they all say it looks fine. None of my neighbors seem to have any problems (I've confirmed that their channels work when ours don't).

I'm at the end of my rope, and satellite is looking better & better, but my wife doesn't want a dish if we can help it. Any ideas on what it could be & how we can fix it would be greatly appreciated. Thanks.
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post #2 of 9 Old 03-13-2011, 08:27 AM
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Did they check the connection on the pole? Had a similar problem (analog ingress) with Comcast at my mothers house which ended up being a bad connection at the pole. (Water damage) This is of course after they insisted the house needed re-wiring. I had to make sure I was at the house to show them where the problem was. (3rd service call)

As soon as FIOS was available, the bad Comcast experience made the decision to switch a no brainer.
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post #3 of 9 Old 03-13-2011, 08:52 AM - Thread Starter
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They claimed to have checked from the house to the pole, but I have my doubts (especially since there were 3+ feet of snow on the ground during two of the visits).

Anyone know if water seepage is more likely to affect the higher frequency signals? I want to be armed with as much info as possible to counter TWC's reluctance to replace the wire from the pole.

As for FIOS, I would switch in a heartbeat, but my neighborhood doesn't appear set to get it anytime soon. Besides, I think they're only offering Internet service in my area (Schenectady, NY) for the foreseeable future...

As an aside, does Verizon ever install FIOS where their right-of-way is overhead?

Thanks.
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post #4 of 9 Old 03-13-2011, 09:15 AM
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Quote:
Originally Posted by yte0012 View Post

As an aside, does Verizon ever install FIOS where their right-of-way is overhead?

If by overhead you mean aerial (inner duct attached to telephone poles) then yes they absolutely do.
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post #5 of 9 Old 03-13-2011, 10:03 AM
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Quote:
Originally Posted by yte0012 View Post

Anyone know if water seepage is more likely to affect the higher frequency signals?

Absolutely
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post #6 of 9 Old 03-13-2011, 04:01 PM
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If you have signal levels if -18 you have issues and this should have been caught by the techs. Lowest I would remotely accept would be -10 and even that is pushing it. Your signal to noise is also probably shot at those levels.

And only having 2 outlets connected leads me to think either it's a plant problem on the street( probably not the case if neighbors are fine) or a drop line from pole to house. Water will definitely affect the high end and now would be the time to check it, now that hopefully you're above freezing temps where you live.You can even if you want go to the demark point at you house where to outside line connect to the inside and check for yourself. Just make sure you check before and splitters, should be a groundblock there. The techs would have been able to detect it even in freezing weather but if they are leaving you with such poor signal levels I would not put much faith in the ones that have been there already. Just visibly checking a drop doesn't always tell you if it's good or bad. Ive seen newer drops with no cuts nicks or chews be filled with water or just plain bad but it looked just like it came off the reel.

Also you have a cable modem and most cable modems if you type in 192.168.100.1 in your address bar you can pull up your modem diagnostics and see what you have for levels on your Internet frequency. If you check this randomly and notice a significant change of signal that correlates with your tv issue then you can almost be assured it gas nothing to do with your inside wiring. And if you have a motorola modem or arris it will tell you your signal to noise measurement as well. This should be no lower than 32 but preferably higher than that.

I'd call them back and make sure you are left with no lower than -10 with a signal to noise of at least 33 on all frequencies. If it's a street issue it could take longer than that visit , but don't accept that" there isn't anything wrong with the signal" if it's still at -18.

Make sure you find out what you have for signal levels before it hits your 2 way splitter or at the ground block. And then what you have at the set. Good luck and if you have any updates please let us know.
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post #7 of 9 Old 03-13-2011, 04:27 PM
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In my experience, signal dropoff starting around 500-600MHz usually indicates water in the cable or a splitter.
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post #8 of 9 Old 03-14-2011, 03:45 AM - Thread Starter
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Thanks for all the replies - I'll be calling TWC this morning. I'll let you know what happens after the next tech visit.
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post #9 of 9 Old 03-14-2011, 03:54 AM - Thread Starter
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Thanks for all your replies. I'll be back to let you know what happens (hopefully after they replace my drop in the next couple of days).
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