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Contributor
ract
Posts: 11
Registered: ‎01-04-2011

Cable signal strength

Until the digital transition, I never had any need for any Comcast service calls to deal with TV service issues (all channels were analog, no Comcast equipment needed). Since the digital transition, several service calls have been necessary to deal with issues associated with the various Comcast equipment necessary to receive digital channels. Each service tech that visits the house always checks the signal strength on the cable coming out of the wall. In the past, none of them mentioned any problems with the signal strength. The other day, a service tech checked the signal strength and said it was "screaming"; I think he meant it was too strong. He said it was in the "red" on his meter and it should be in the "green". He seemed concerned about this and wanted to fix it; but I refused. My question is what is the down side to having a cable TV signal that is too strong?

Cable Expert
WarEagle57
Posts: 10,674
Registered: ‎12-31-2004

Re: Cable signal strength

You should've let him fix it.

Contributor
ract
Posts: 11
Registered: ‎01-04-2011

Re: Cable signal strength

OK, but why?  I don't understand the harm, if any.  Will my equipment be harmed or will the Comcast system be harmed in some way?

Cable Expert
WarEagle57
Posts: 10,674
Registered: ‎12-31-2004

Re: Cable signal strength

I don't know about harm, but signals that are too strong can result in poor reception and distortion.

Contributor
ract
Posts: 11
Registered: ‎01-04-2011

Re: Cable signal strength

Thanks for the prompt response.  However, everything works perfectly; that is why I am afraid to let them tinker.

Cable Expert
WarEagle57
Posts: 10,674
Registered: ‎12-31-2004

Re: Cable signal strength

OK.  If you subsequently have problems you might mention the signal strength as a possible factor.

Visitor
Ravingndrooling
Posts: 4
Registered: ‎12-07-2010

Re: Cable signal strength

Too much signal is just as bad as not enough. Digital works a little different then analog as far as your video is concerned. With analog, as the signal gets weaker, the picture can get progressively worse. Digital is a waterfall kind of thing. It drops and drops and drops, once it reaches a certain point, it just stops working. Digital also works well with a negative signal level. Don't mis-understand, even though it's a negative number, you are still getting plenty of signal. The whole cable system is designed to run at a certain level(dbmv) at the back of the box. If you are getting too much signal, something is wrong...Either an amp or a node is out of balance or a house amp is in play when it shouldn't be. I would suggest you keep having them come out until it is fixed. If it's too much signal, it is THEIR problem and needs to be fixed. If it's not enough signal, it could be numerous things....When the tech came out to your home, did he pull off your wall plates and check the connection behind them, did he change the splitters and connections at the side of your house or in the attic if necessary? You could have a bad piece of cable as well. Analog will tolerate a lot more then digital will, before things go south. I say keep calling until its fixed...if it gets to be out of hand, start asking for compensation..... 

Contributor
ract
Posts: 11
Registered: ‎01-04-2011

Re: Cable signal strength

[ Edited ]

Thanks for the prompt response. This is not Comcast's fault and there does not appear to be any reluctance on the part of Comcast to fix the problem. The service tech was eager to jump in and start taking my set-up apart to run checks and replace equipment. He seemed concerned about the problem and wanted to fix it; but I refused because all the equipment appeared to work perfectly. I was also surprised since none of the service techs that have ever visited (most service calls have been in the past year) mentioned this problem. Despite the horror stories that I see on the forums, blogs, etc., I have been pleased with the Comcast service for the most part. The TV and internet service has been practically problem free. When the Comcast service techs have shown up to perform these onsite service calls, they have shown up on time and performed well.

 

I was happy with analog TV; I watch no sports and watch most movies in the theater or on DVD. Until the digital transition, I never had any need for any Comcast service calls to deal with TV service issues (all channels were analog, no Comcast equipment needed). Below is a description of my pre-transition set-up and current set-up. The primary TV (along with all of the DVRs) is located on the second floor. Since the digital transition, several service calls have been necessary to deal with issues associated with the various Comcast equipment (mostly cable cards) necessary to receive digital channels. At some point during the transition, I began to lose digital signal to the equipment on the second floor; this never happened with analog. I added a Motorola Model BDA amplifier. The amplifier is located close to the incoming cable and serves all equipment, except the office TV and internet modem. This is probably the cause of the problem; however, when I take the amplifier out of the set-up, I lose signal on the second floor.

 

Using the only diagnostic tool I have (the TiVo DVR diagnostic function), the signal strength is 100% and SNR is 37, which according to TiVo indicates a too strong signal.

 

Of course, as a consumer, fear sets in when someone wants to tinker with some electronic equipment that appears to be working correctly. Anyway, I plan to discuss this with Comcast and see if some other solution is available to fix the problem. Thanks for everyone's help.

 

 

PRE-TRANSITION SET-UP

 

Analog TV, with three single-tuner analog hard disk DVRs [with TV Guide on Screen (TVGOS) programming info] & standard cable service (no Comcast equipment/have always disliked the idea of set top boxes, bulky/no interest in VOD)

 

Two secondary analog TV's (kitchen and office, downstairs); one other analog TV (upstairs) with no Comcast equipment.

 

 

CURRENT SET-UP

 

HD plasma TV, with cable card, as primary TV; Comcast DVR service and Digital Preferred package; and two Tivo DVRs, only one with a cable card. Although most recordings are SD versions of local network shows, some were cable channel (i.e. TNT, USA, & FX) shows (due to the elimination of most analog channels via the digital transition, a cable card was needed for the Tivo to pick up these shows).

 

Two secondary HD LCD TV's (kitchen and office, downstairs), with digital adapter service for each; one other HD LCD TV (upstairs) with no Comcast equipment (QAM tuner).

 

Visitor
Ravingndrooling
Posts: 4
Registered: ‎12-07-2010

Re: Cable signal strength

OK, let's take this apart one piece at a time. Did your service techs check all the fittings? Even the ones behind the wall plate? This is important! It doesn't take more then one bad fitting to bother a digi box/dvr. Even with a "low" signal, I have seen digis run fine as long as the fittings and cable were all perfect. You stated you bought a house amp, does the amp in question have a return path? It should state this on the amp. If it does not, it will cause problems. Digi boxes run on a two way system. If the box can't send signal upstream it will eventually shut itself down. Now, if you have to use an amp, and it is putting out too much signal for your box, there are attenuators that will cut the signal and can be put behind the boxes themselves. If you are only having problems upstairs, maybe there is a way to isolate those outlets and only use the amp for them? Digital info is sent on much higher freqs then analog, so the loss of signal per foot of cable compared to analog is much greater. Almost twice depending on the channels that you are having problems with. If I had to guess, you are having problems with a group of channels, not just one. You are more then likely having problems with a particular "QAM" or group of digital channels. I understand your reluctance to have a tech adjusting things, but, if you want it to work the way it is supposed to, I don't think you have a choice. If I had you for a service call, knowing what you have told me so far, I would start from the beginning and change everything(splitters, fittings, jumpers) and check the signal at every point that I could. This would also rule out there being a bad piece of cable. You may find you won't even need a house amp, but you DO have to let the techs do their job to find out.  There is a science to it for sure, but making it an art helps too. I stopped counting how many digis I have installed or serviced after 5000....so, I am pretty good with them...I have been an installer, service tech for over a decade with a couple of years of line tech thrown in for kicks, but I don't know it all...LOL If you have other questions, please email me, I'm more then happy to answer anything cable, inet or phone related. Even though I have never worked for Comcast, the cable system works the same.