Cable Noise Reduction

[drparent]

Alright, here's the deal:
I've noticed that my cable signal has gotten noisier in the past few months. I want to improve the picture quality. The problem is, I'm getting conflicting reports on what kinds of devices can decrease video noise.

I've been told that I need a signal booster/amplifier, and that this will improve the picture quality. I did a bit of research, and I came across multiple explanations of amplifiers, how they work, and what they do. Some of them say that amplifiers used close to the source will "improve picture quality" when you have long runs of cable. Others say that if you use amplifiers, you will "increase the signal strength," but introduce MORE video noise and other distortions.

So what do I need?
Is an amplifier still the way to go as long as I don't use a bunch of them in the same run of cable?
If I do need an amplifier, how do I determine the dB level that is appropriate for my situation, and should I go powered or powerless (or does it matter)?

Note that I don't want to use a software filter - this is affecting my TV watching as well as my capping.

If you can't give me an answer, can you direct me somewhere where I might find one? I'm just about Googled out, and I'd rather not deal with the guy at Radioshack...

[edDV]

Alright, here's the deal:
I've noticed that my cable signal has gotten noisier in the past few months. I want to improve the picture quality. The problem is, I'm getting conflicting reports on what kinds of devices can decrease video noise.

I've been told that I need a signal booster/amplifier, and that this will improve the picture quality. I did a bit of research, and I came across multiple explanations of amplifiers, how they work, and what they do. Some of them say that amplifiers used close to the source will "improve picture quality" when you have long runs of cable. Others say that if you use amplifiers, you will "increase the signal strength," but introduce MORE video noise and other distortions.

So what do I need?

You need to contact your cable comapny and TELL them to fix the problem. If this happened recently, someone may be illegally tapping off the signal upstream of you. This happens often in apartment buildings, etc. The cable company will kick them off and adjust your levels.

In a normal house to house cable system, the video gain is adjusted on the telephone pole outside. If your level is low, you may see noise increase as you split the signal. If the signal is too strong, you will see noise with only one device connected and often have sound distortion as well.

Get the cable company to fix it.

[lordsmurf]

Your cable line is messed up. Tell those lazy SOBs to go and fix it.

My cable company tried to tell me over and over "it's the lines in your house" until a storm knocked over the poll and ripped wires off my home. Turns out, when they replaced all the wires, the signal was suddenly clean.

My fault, my ass.

Don't put up with cable companies, they will jerk you around all day just to avoid fixing broken crap that is THEIR FAULT.

[drparent]

Get the cable company to fix it.

I've called the cable company and they're looking into it, but that still doesn't answer the question of what effect an amplifier actually has on video noise and in what situations those effects occur.

My levels may have dropped because more people in my area are switching to cable internet, and I don't know how much the cable company can do about that without doing some major work on the lines.

I'd like to be educated on the topic in addition to fixing the problem. Even if it was someone stealing my cable, would an amplifier help?

[edDV]

Get the cable company to fix it.

I've called the cable company and they're looking into it, but that still doesn't answer the question of what effect an amplifier actually has on video noise and in what situations those effects occur.

My levels may have dropped because more people in my area are switching to cable internet, and I don't know how much the cable company can do about that without doing some major work on the lines.

I'd like to be educated on the topic in addition to fixing the problem. Even if it was someone stealing my cable, would an amplifier help?

Back when I signed up for "digital" channels here, I was on the end of the street and the signal was unstable. Their first guy played around with it but only made things worse. I complained loudly and got the supervisor tech out there. They finally added or replaced amps all the way up the main street to correct the problem.

Once the signal is bad, you can't do that much to get the noise out. Cable systems use modulated RF over zero to 550-850+MHz bandwidths divided into 6MHz channels.
http://electronics.howstuffworks.com/cable-tv.htm

Lower "analog channels" are similar to over the air RF channels and show similar noise issues. Analog noise reduction may work on those channels.

Noise introduced at the RF level for upper "digital" QAM MPeg channels causes demoulation errors that are much worse than simple noise. It will be more difficult to correct those errors.

The cable repair guy will bring a scope and attempt to flatten the RF frequencey response over the full 550-850 MHz bandwidth and then set the gain. Simple splitters should be sufficient in the house. Any amplified splitter would need to maintain flat RF response over as much as a GHz depending on how modern your cable system is. Otherwise it will do more harm than good.

Some cable amplifiers are designed only for the lower "analog" channels and lack the bandwidth equalization to pass the upper "digital" channels and may block capability for two way internet cable modem.

[junkmalle]

that still doesn't answer the question of what effect an amplifier actually has on video noise and in what situations those effects occur.

An amplifier simply amplifies the incoming signal. If the signal coming into your house is noisy the noise will be amplified along with the signal. If the signal coming into your house is clean and then is attenuated by bad cabling or too many loads (TVs, VCRs, etc) an amplifier may help.

my cable signal has gotten noisier in the past few months

That pretty much points at a problem outside your house. Unless you've made changes to the wiring in the house or added more loads.

[drparent]

I decided to lug my computer around and test all my cable outlets, since my monitor is better than any of my TVs. I determined that the outlets downstairs have a significantly better picture than the ones upstairs (almost no noise at all downstairs, in fact).

I'll have to mess with my setup and see if I can get a better picture upstairs. There isn't anyway I can attach something between the downstairs and upstairs cables since they're all inside the walls. (God, I hope I don't have a rat chewing on wires in there...)

Thanks for your responses.