Just recently switched from Dish to Comcast (long story, don’t ask. The reasons belong in a pit thread about the Mountain West Conference and their stupid media deal with CSTV and Comcast, but I’m not going there).
Anyway, I have noticed when I’m watching some of the digital channels that from time to time the picture will freeze for a couple of seconds, then break up with a lot of pixellation of the picture, and then resume normal viewing.
For you video gurus out there, is this more likely to be a problem with:
[ul]
[li]My receiver? (I doubt this one)[/li][li]The wiring inside my house?[/li][li]The wiring between the cable company and the house?[/li][li]The equipment at the cable company?[/li][li]The network transmission between the “source” and my cable company?[/li][li]Some combination of the above?[/li][/ul] Is there a technical name for this phenomenon? I’d like to know what I’m talking about when I call to complain.
[QUOTE=FatBaldGuy]
[ul][li]The network transmission between the “source” and my cable company?[/ul][/li][/QUOTE]
Bingo. Cable distributors generally get their source from satellites in the form of digital signals. If something, such as heavy rain clouds momentarily interrupts the signal, you get that pixellation, caused by missing or incomplete picture information–you can see similar effects when watching digital satellite TV such as your former provider.
From what you have supplied, it could be any of those things. The phenomena is caused by a signal drop or corruption in the feed, so bad that the system is unable to do full error-recovery and shows you the best image it can put together at the moment.
Can you narrow it down? Like, just one channel, just a time of day, just one TV set, just one show (I have noticed it happening more in sporting events where there are remote cameras).
My WAG is it is probably upstream from your TV, since cable & satellite companies and TV source signals have error correction, but I don’t think end-viewer TVs do (I could be wrong). If you have a second TV or a spare cable, this would help diagnose it.
Thanks for the quick reply. I did see this very rarely on dish, but it seems to happen a lot on Comcast. I’m wondering if they just have a lot of poorly maintained receiving dishes at my local office.
This problem drove me from cable to DirecTV. In our case, the cable co’s Earth station is some distance from our town. The signal is then microwaved to a tower at the cable company here in town, and then distributed to subscribers. If there was a cloud somewhere between the Earth station and town, the signal would degrade. For digital channels, we got the described pixilation. For analog channels, we got snow.
I had this problem once too and the solution was to get the cable guy out to the house to test the line at the TV. I then had to replace the RG59 cabling from the basement splitter to the TV with RG6. Digital channels transmit more data than the RG59 cable could support. After the cable upgrade the channels came in fine.
It could also be a low quality splice or splitter in line with the feed (probably somewhere in your house wiring).
I did the wiring upgrade myself so I know that the solution was in the new cable.
Q.E.D. has it. We have cable here in Colombia and sometimes we get a little breakup between the Cable company and the Sattelite. When I asked them about that, they confirmed it.
That’s interesting, because when we changed over to cable Comcast sent an inspector a few days after the install to verify everything.
He said that the cable running from the equipment block on the outside of the house to the splitter in the basement was RG59, and that the installer should have replaced it with RG6. We had them come out and replace the cable, but we were having the video problems before the change and after the change with no noticeable difference.
Even so, the cabling inside your walls might be RG59. Or there is a splitter somewhere else in the house in line with your tv that’s not rated for 1+GHZ.
Could even be a case of a loose connector or a poorly prepared end fitting.
I would think that the cable guy could test the signal at the main splitter and then go to your tv and check it there.
No, I can guarantee that all of the cable between the splitter and my receiver is RG6 and installed properly, because I did it myself. I’m inclined to agree with Q.E.D. that it is weather interference somewhere upstream.
I recently had cable installed. When we first brought it up this was happening on some stations (not all) almost continuously. The cable guy tested the lines and connections and stated that, while our signal was within the normal tolerance, it was on the low side of that scale. He said our cable is running a long way down the street, which could be why the degradation of the signal.
So he installed a repeater/amplifier/whatever box where the cable hits our house. This eliminated about 98% of the problem, although I do see it happen once in a while.