Unlike broadcast television, cable television's origins were unportentous: known as CATV (Community Antenna Television), cable was first used to deliver a clear signal to rural communities. At the time, a CATV system generally consisted of a single large antenna mounted in a high, clear area to receive signals from distant broadcasters. Cables were fed to the houses in the community, usually delivering two or three channels. In the mid-1960s, new technology allowed for up to twelve channels to be carried through a single cable. In order to fill these new channels, cable operators began to import television signals from more distant sources, allowing viewers to watch stations from large cities and neighboring states. With access to a wider variety of stations, the demand for cable increased.
Apart from dramatically improved reception, cable television held the capacity for educational, cultural, and community service, since it was feasible for cable systems to be bidirectional: viewers could use their cable television to answer questions or participate in polls, among other things, all from their armchairs. Still, though cable penetration increased steadily, it did so very slowly.
In the early 1970s several small companies in California and on the East Coast began offering pay-per-view broadcasting: first-run films and major sporting events delivered by cable to a viewer's home for a monthly fee. This caused demand to skyrocket, and by 1975 the first nationwide pay-per-view cable station--Home Box Office (HBO)--was in service.
What makes cable transmission practical is its use of coaxial cable, which consists of an insulated tube of conducting material that contains a central conductor at its core. The thick, layered cable allows transmission of a wide band of frequencies and rejects interference from automobiles, electrical appliances, and the like. As coaxial technology improved, the number of stations available to cable operators rose from twelve to more than fifty; with the help of digital video compression, that number can be increased to almost 150. The antennas once used to deliver a signal to a cable system are long since gone, replaced by microwave dishes often fed by communication satellites. Once a signal is delivered to a cable company in this manner, it is distributed over cable lines to customers. Broadcasts are often scrambled to prevent non-subscribers from splicing into a cable line without paying for the service.
In the mid-1990s, coaxial cable began being replaced by fiber optic cable, or a combination of both called hybrid fiber-coaxial (HFC). Fiber optic cable, which consists of thin strands of glass, and the combination are superior because they can carry more channels and improve the quality of the signal. In 1998, about 50% of all subscribers got their cable via fiber-optic technology, and that number continues to grow. With digital compression, in which the video signal is compressed digitally, many more viewing options are available to consumers. This also reflects the proliferation of cable television networks that now can find space on cable systems.
Another area of innovation in the cable television industry is the combination of television with computers. The twenty-first century could bring widespread use of these infant technologies. Set-top computer boxes will sit on most new digital televisions; these boxes have computer chips to manage a variety of information and entertainment possibilities, including the increasing number of available networks. The boxes also transmit better picture and sound. Cable modems are superior to computer modems using telephone lines because they have a high capacity and high speed connection is readily available in most non-rural areas. Cable modems have many of the same functions as telephone modems, including Internet access and telecommuting.
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