Yup. Cable TV is common usage for CATV or Community Antenna Television. CATV was just MATV (Master Antenna Television) on a grander scale. A MATV system would serve a building or group of buildings under common ownership from a single antenna or antenna location. A CATV system took this a step further and served whole towns. It had its roots back in the 50's in areas that were blocked by hills or mountains and couldn't receive off-air reception. Somebody had the idea to put an antenna on top of the mountain and run a cable down to the town and then to each house. This worked better than a repeater and didn't require an FCC license.
Then with the advent of satellite delivered programing that debuted HBO and Showtime and a bit later MTV and Playboy in the 80's CATV became the "golden egg" for a lot of entrepreneurs who saw the opportunity to make a lot of money. And make money they did because in about 10 years all these small operators were bought up by the few MSO's (multiple system operators) that we have today.
Technologically CATV went from at most 12 channels (or whatever was available off-air)to 35 and now to hundreds. As Joe mentioned, when the channel capacity got up there so did the frequency spectrum that it required. Even though this frequency spectrum was "sealed" within the cables of the system leakage does occur. Because some of these same frequencies are used over the air for such things as aircraft navigation cable engineers were forced to deviate from the standard channel assignments so that carriers on the cable were not near these critical terrestial frequencies. HRC and IRC offsets allowed amplifiers to operate with less harmonic distortion.
One of the biggest advances was when fiber replaced coaxial trunks. Trunk lines can be thought of as like primaries that feed step down transformers that in turn serve neighborhoods. The reason for this was not a higher quality signal but rather it allowed set top boxes to to send a signal back to the head end for pay-per view. This was never really successful with the old coaxial trunks because no matter how well you built the plant, sooner or later things would loosen up and ingress from RF sources outside the cable system stomped all over your return signal.
So, now that cable operators had the higher bandwidth of fiber they began to think of other revenue producing avenues besides more channels of drivel. Digital cable along with broadband internet and telephone is what they have come up with so far. But keep in mind, as far as the signal on the fiber and coax, it's still good old analog.
-Hal
