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Cable television (CATV), also known as cable television, was developed from wireless television and first appeared in Pennsylvania in 1950. Cable TV still retains the broadcast system and signal modulation mode of wireless TV, and does not change the basic performance of the TV system. Cable TV sends recorded programs to users through cable (cable or optical cable), and then replays them on TV without radiating electromagnetic waves into the air, so it is also called closed-circuit television. Cable TV is a kind of pay TV that is paid by viewers rather than funders.
Cable Television (CATV for short), originally referred to as "public antenna television", now refers to all the cables or fiber optic copper cable hybrid systems used to transmit video signals to communities and households. The earliest cable television business appeared in 1948, when the cable television network was used to realize the simple retransmission of radio and television programs. In the early 1980s, cable TV network achieved a large coverage all over the world. Cable TV network enterprises are operating enterprises that provide cable TV services to users.
advantage
As the TV signal is transmitted through cable, it is not blocked by high buildings and mountains, so the viewing quality is good.
Cable TV can use adjacent frequency transmission, unlike wireless TV, which must use frequency separation transmission in a region to prevent interference, so spectrum resources can be fully utilized to provide more channels.
Cable TV can also realize two-way transmission of signals through cables, provide interactive two-way services, and easily realize charge management and carry out a variety of paid services.
Cable TV stations do not need expensive transmitters and huge iron towers, so the cost of building stations is low, which is conducive to rapid development.
The cable TV system not only receives and retransmits the programs of the big TV network, but also provides programs with different thematic content recorded by itself, providing subscribers with more program choices.
history