TV channels and program pre-selectors are two different concepts. Strictly speaking, a channel is a frequency range, and a television channel specifically refers to a television program transmitted in this frequency range. The frequency resources are owned by the state, and the government information industry management department is responsible for planning, management and supervision. According to the channel division standard of China's radio and television, each channel station uses 8MHz bandwidth. Because of the factors such as FM radio inserted in the middle, 68 TV channels can be arranged in the frequency range used by the actual TV in the sky. If it is wired The closed-circuit television system transmits television programs. Because there is no other radio service, 38 TV channels can be added on the basis of 68 TV channels, called supplementary channels.
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In other words, the color television receiver can receive 106 television channels under theoretical limit conditions. In fact, there are rarely more than 20 TV channels for actual wireless broadcasting in the same region. Even if cable TV systems with more TV programs are now transmitted, systems capable of transmitting more than 60 TV programs are rare.
The television program preselector of the liquid crystal television has the task of storing the relevant parameters of the television channel received by the antenna or the cable television system into the memory, and the parameters of a television channel are stored in a storage unit, each unit being commonly known as a unit. A program pre-selector (and many people call it a channel). A memory integrated circuit capable of storing 100 television channel information and a memory integrated circuit capable of storing 200 television channel information, it is difficult to say that the price should be different, and the technical difficulty is basically the same. .
However, from the perspective of facilitating the use of rear-projection television, each television program channel exists in a pre-selector. When actually watching a television program, it is easier to find a desired television program, and it is also convenient to find, compare and select a television program.
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