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dalepa

join:2012-03-19
Houston, TX

[DVR] Can someone explain this?

Click for full size
I just got cable and dvr rng200 yesterday and plugged it in... I then noticed that ch629 was pixelating at tie and got worse when I actually wanted to watch my first show, and now today it's giving me "one moment please" message

I only have 3 HD channels that are out, while the other 17 HD channels and all the non HD channels are fine.

I tried a different non dvr receiver and it has the same problem...

From the RF Statistics page, the Current QAM Status and Level is yellow for the 3 channels only as seen in the image above.

I was hoping that someone could explain how RF could be bad for some freq and and not the others if a bad cable is involved?

Or maybe there is some issue at the signal source, or maybe just these freq have interference?

I'm having a cable guy come out, but my first impression of Comcast's DVR and channel setup is really bad as compared to coming from dish 2 years ago.


FifthE1ement
Tech Nut

join:2005-03-16
Fort Lauderdale, FL

This happened to me before and it was my cable. Once it was changed my channels came back. I thought it was odd that only a few channels stopped working and all the rest worked. But I'm betting that is what happening to you too. And my issue creeped up on its own out of the blue one day. Give changing the splitters and cables a chance and let us know what happened?

5th
--
"The relationship between what we see and what we know is never settled..."


dalepa

join:2012-03-19
Houston, TX

Click for full size
Maybe some one is watching here, after 2 days of pixelations and completely being out today, ch629 came back right after posting this...

I'm getting a lock at -9 dBmV and I'm still getting Lots of Corr Bytes, but no pixelations yet...

dalepa

join:2012-03-19
Houston, TX

Started to get some pixelation again...

I just noticed that ch621 is having pixelation, and I noticed that the Freq is the same (669mhz) on BOTH ch621 and ch629 channels which are the worse.

I have 2 other channels that share Freq on 501MHz and both having Pixelation issues.

So multiple channels share the same Freq?

Other HD channels are not having any issues.



SeaSeaTee5

join:2010-05-06
Maryland
reply to dalepa

Looks like a suck-out in the area of that QAM. You need a service call. Could be anything from an in-house to a plant issue. A tech should be able to check that specific frequency and determine the cause. I've seen it caused by anything from a bad jumper, a damaged drop or even a bad amp out on the plant.


dalepa

join:2012-03-19
Houston, TX

Thanks for the info...

I didn't realize that there are factors that can effect one frequency channel and not the others...

I assumed that if there was an signal issue with one HD channel, they all would have issues.

But from looking at the status, just 2 Freq are having problems causing 4 channels to be out.


dalepa

join:2012-03-19
Houston, TX
reply to dalepa

Looks like I found the problem.

There is a 1 in to 4 out way splitter in the attic, and when I unplug 2 of the out cables, the signal is better...

So can anyone suggest a better 4 way splitter, or other ideas?


dishrich

join:2006-05-12
Springfield, IL

said by dalepa:

Looks like I found the problem.

There is a 1 in to 4 out way splitter in the attic, and when I unplug 2 of the out cables, the signal is better...

So can anyone suggest a better 4 way splitter, or other ideas?

Well first of all, the fact it gets better JUST by unplugging 2 other cables, tells me it may NOT be a splitter problem, per se. Regardless of how many (active) cables you have connected to a splitter, it STILL "draws" the total signal down to whatever (remaining) sets you have connected. The fact it gets better by disco'g lines, tells me you might have some sort of issues on those other drops. (bad cabling, connectors, shorts, etc.) Those kind of issues (on other lines) can cause problems back through the splitter, & through the other lines/sets.

Assuming you really use those other (2) drops, you're going to need to thoroughly check those outs; maybe replace bad connectors, wall plates. Maybe it's old cable that should be totally replaced in the first place.

If you are NOT using all 4 ports on the splitter, then you should get a smaller, appropriate splitter & ONLY connect the drops you're actively using. That right there alone might solve your problems...


SeaSeaTee5

join:2010-05-06
Maryland
reply to dalepa

Here's one of the 4-way splitters Comcast uses:

»www.amazon.com/Antronix-CMC2004H···splitter

A suck-out may only affect 1 QAM, but can easily affect more. 1 QAM can carry anywhere up to 12 channels. If it has all HD channels on the QAM, it might only affect 3 channels. The adjacent QAMs could be affected as well, but they may be channel numbers that are nowhere near to the channels you are noticing.

Hopefully it's just the splitter. A service call would find out for sure and the tech will replace the splitter with a good quality one like the one above.


dalepa

join:2012-03-19
Houston, TX
reply to dishrich

yep, looks like i might have bad cables and/or connectors... i bet the splitter is fine..

Do rats like to chew cables? one cable had several places that metal is showings and it looks like something has been chewing on it.

I'm showing -8 now and no problems... Is -8 normal, or should that be higher with 2/1 split?



SeaSeaTee5

join:2010-05-06
Maryland

Yes, rodents like to chew on cable to keep their teeth sharp. Squirrel chew on outside cable is pretty common.

Your signal will double when you go from a 4 way to a 2 way splitter. Generally -10dBmV is the minimum amount of signal needed for a digital signal. You are right on that threshold so I'm not surprised that your picture would go in and out depending on which splitter you are using.

If you have damaged cable you are possibly letting in ingress as well. Not only could this affect your picture quality, but it can also add upstream interference on the cable plant. This could not only affect your modem performance, but can affect others in your node as well. If it's bad enough, your service could be interrupted until it is corrected.


dishrich

join:2006-05-12
Springfield, IL
reply to dalepa

said by dalepa:

one cable had several places that metal is showings and it looks like something has been chewing on it.

If you still need those locs active, you then MUST replace that cable somehow...ANY metal showing is not good.


flwpwr

@comcast.net
reply to dalepa

Interesting theories especially the suck out on certain frequencies.

That said...
Your levels are not that bad that I woudl expect a OMP message, more likely there is an issue somewhere with the signal.

If you have a neighbor you can cask see if they see the same thing. 669 Mhz is up there so unless its some sort of cellular data carrier its probably just someone did not tighten something down correctly but the SNR says 27 which is low for a 256 qam carrier. Just checked my box mine says 37 on that frequency range. With -10 dB/mV I would say no less than 32 should be there, and more likley 34+. I would remove the cables from the wall and box and reconnect them, make sure to put some gumption on it, no limp wristing, if no improvement call in.