During the 1980s and early 90s, the growing number of cable networks, improved programming, increased channel capacity (which reached 150 in some systems by 1992), and greater freedom in terms of programming content greatly expanded the industry. There are 10,828 operating cable systems in the United States serving 28,798 communities and 62 million subscribers; this comprises about 64% of all households. Viewers pay a monthly fee for a package of cable television programming, known as basic cable, and additional monthly fees for networks such as HBO, which are known as pay TV services. Cable television offers a wide variety of specialized programming, including channels devoted to specific interests, such as news, sports, movies, business information, weather, cooking, home shopping, and family viewing. It can also transmit programs from foreign cities, such as the proceedings of the British House of Commons. The industry finances its programming from subscriber fees and advertising revenue. New technologies, such as fiber optics, digital compression, and interactive television, allow cable operators to offer more programming choices and services. The cable lines installed by cable operators are also to use to provide broadband Internet access to the homes of subscribers.
See G. Mair, Inside HBO (1984); T. Baldwin, Cable Communications (1988).
The coaxial cable, which is virtually immune to external interference, consists of two concentric conductors separated by an insulator; the current in the inner conductor draws the current in the outer conductor toward the center rather than letting it dissipate outwards. Because they can carry a large number of signals simultaneously, coaxial cables are also used in cable television systems. The newest form of cable is the fiber-optic cable, developed in the 1970s. Instead of a copper conductor, a silica glass fiber carries digitized signals as pulses of light.
The insulated wire that conducts electricity from generator to consumer is also called a cable; it often contains multiple conductors and must be of sufficient gauge to carry large currents. Its insulation must withstand high voltages.
See his letters, ed. by L. L. Leffingwell (1928, repr. 1967); biography by L. D. Rubin (1969); study by P. C. Butcher (1959).
System that distributes television signals by means of coaxial or fibre-optic cables. Cable television systems originated in the U.S. in the late 1940s to improve reception in remote and hilly areas, where broadcast signals were weak. In the 1960s they were introduced in large metropolitan areas where reception is sometimes degraded by reflection of signals from tall buildings. Since the mid-1970s there has been a proliferation of cable systems that offer special services and which generally charge a monthly fee. Besides providing high-quality signals, some systems can deliver hundreds of channels. Another feature increasingly offered by cable operators is two-way, interactive communication by which viewers can, for example, participate in public-opinion polls as well as connect to the Internet. Cable operators are also involved in the development of video compression, digital transmission, and high-definition television.
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