小默 發問時間: 社會與文化語言 · 10 年前

Channels in a television

There is how many channel in a television?

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I do not want translation. I want to know how many channels are in a television. I need it for my reseach paper.

3 個解答

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  • 10 年前
    最佳解答

    A television channel is a physical or virtual channel over which a television station or television network is distributed. For example, in North

    America, "channel 2" refers to the broadcast or cable band of 54 to

    60 MHz, with carrier

    frequencies of 55.25 MHz for NTSC analog

    video (VSB)

    and 59.75 MHz for analog audio (FM),

    or 55.31 MHz for digital ATSC (8VSB).

    Channels may be shared by many different television stations or

    cable-distributed channels depending on the location and service

    provider.

    Depending on the multinational bandplan

    for a given region, analog television channels are typically 6, 7, or 8 MHz

    in bandwidth, and therefore television channel frequencies

    vary as well. Channel numbering is also different. Digital television channels are the same for legacy reasons, however through multiplexing,

    each physical radio frequency (RF) channel can carry

    several digital subchannels. On satellites, each transponder

    normally carries one channel, however small, independent channels can

    be used on each transponder, with some loss of bandwidth due to the need for guard

    bands between unrelated transmissions. ISDB, used in Japan and Brazil,

    has a similar segmented mode.

    Channel

    separation on over-the-air channels is accomplished by skipping at

    least one channel between two analog stations' frequency allocations. (It should be

    noted that there are gaps between certain channels, where numbers are

    sequential, but frequencies are not contiguous, such as the skip from VHF

    low to high, and the jump to UHF.) On cable TV, it is possible

    to use adjacent channels only because they are all

    at the same power, something which could only be done over the air if

    the two stations were transmitted at the same power and height from the same location. For digital TV, selectivity is inherently better,

    therefore channels adjacent (either to analog or digital stations) can

    be used even in the same area.

  • 10 年前

    How many channels are there ...?

  • 10 年前

    There is how many channel in a television?

    電視有多少頻道?

    參考資料: 自已
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