CATV Signal Level - need input please. [Archive] - Audio & Video Forums


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01-24-2005, 11:23 AM
Does anyone know what a good, normal level, cable signal is (I assume in dB's). Source level that is, before any kind of splitters, etc. Got a new 60" Sony LCD and want to get everything hooked up and set-up right. Trying to figure out if we have a weak signal and need an amplifier or if the signal is too strong - which is kinda what the cable company has hinted at.


01-26-2005, 09:03 PM
Don't quote me on this, but I believe a good signal coming into the house is around 20dB from the street. I can't remember exactly since it was a long time ago that I was last troubleshooting signal levels. I know cable modem needs to see a slightly higher signal level than a digital cable tv box to operate. If I am not mistaken a cable modem needs to see at least 0-5dB at the outlet, wheras a digital tv cable box must only see around -5dB to 0dB in order to operate. Corrections welcome of course...

01-27-2005, 02:28 AM
What indications of problems do you have? Attenuators (not just boosters) are available at RatShack if your signal is too strong.

Generally, if you have enough signal to drive at least one setup (with no splitters) they will consider you good to go. I started out with one TV and one VCR.

Later, I was able to split the signal several times and still maintain a good picture on 4 TV's, 3 VCR's and a cable modem (off the first split) without needing additional equipment.

That's indicativce of a pretty strong signal and I never had a problem.

01-27-2005, 06:30 AM
Well, this is a new home in a new neighborhood. We moved in Dec. 3rd and, if I remember correctly, the picture was pretty good. Only recently have I noticed most of the analog channels are grainy and wavy. I can see these ghostly lines in the picture and it just looks bad. I know we had a better picture at our previous home, same setup. Anyways, Comcast came out and said the signal level was too high and was causing the problem. I think my wife said he measured it at 18dB. I have a 4 way splitter and a cable modem also. I do have an amplifier, variable gain from Radio Shack but haven't tried that yet. Weak signal or strong one??? Heck I don't know. Can too strong of a signal damage any equipment?

Thanks again.

01-27-2005, 06:32 AM
I think I'm gonna bypass the splitter and hook the source coming in directly to the main living room feed. If my picture gets better, it's a weak signal problem. If it get's worse, it's too high. By the way, Comcast has done nothing to correct the problem. They had to put in another service order for a line tech to come out. Who knows when that will be.

01-27-2005, 03:03 PM
I think I'm gonna bypass the splitter and hook the source coming in directly to the main living room feed.That's a good place to start. Look at what I'm running (also comcast) and I don't need a booster.

Booster amps cause more problems than they solve since they can overdrive the receivers, even at what you would consider a low setting.

I'm using an old RatShack 70 channel amp with variable gain on my FM antenna system which is split three ways. I have the gain set as low as it can go and the gain is still remarkable.

Remember, Rat Shack sells cheap signal attenuators if the signal IS too strong.