Line extenders (A.K.A. amplifiers) exisist at many points among a CATV route. These are quite different from an amplifier that you buy at Radio Shack, since they do a lot more than just amplify the signal. Line extenders actually repeat the signal and many times, DC power is inserted into the cable run to compensate for voltage drop, hence the name extender
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These are the fairly large bolted rectangular aluminum housings that you will see along aerial runs near poles. LE's can also be installed in pedestals, but only the larger ones and the pedestals typically include ventilation louvers to aid in heat dissipation. The dinky distribution pedestals (6" square or so) only include taps, or "splitters".
LE's have to be adjusted to compensate for temperature swings on a regular basis. Since metallic conductors offer more resistance when they are hot and less when they are cold, this is a constant maintenance issue for CATV companies.
Filters within pedestals are generally used to simply block subscribers from gaining access to channels or services that they aren't paying for. Nowadays, digital cable is becoming the norm, so the addressing of the cable receiver boxes actually control what you get and what you don't.
If you have more than four cable runs to sets, you probably should consider your own "personal" amplified splitter. Long cable runs, especially when done with low-quality builder's grade COAX cable are usually the culprit for poor signal quality. In addition, the electricians who install these cable runs frequently lack the proper crimping tools. They simply "mash it with their Kleins". This distorts the dielectric insulation and causes all kinds of wacky performance.
You can amplify the signal this way, but if the outgoing cables are bad, or poorly-terminated, you will see random performance. If the incoming signal is bad, then you will experience similar performance from all devices connected behing the amplified splitter.
There is a very good chance that your signal coming in is actually too "hot". An especially strong signal is just as bad as a weak one with regard to picture quality or Internet connectivity.
