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文件名称:关于CATV美国标准
文件大小:114KB
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更新时间:2014-09-12 16:00:17
CATV美国标准
In the US, a TV channel is a 6 MHz wide chunk of bandspace. The bottom edge of the over-the-air channel 2 is 54 MHz and
the upper edge is 60 MHz. Within this 6 MHz space is a video carrier, a color carrier, and an audio carrier.
The frequency of the video carrier is 1.25 MHz above the lower edge, so for TV Channel 2 the video is at 55.25 MHz.
The color carrier is approx. 3.58 MHz above the video carrier (N.B. not the lower edge), so for TV Channel 2 it is 58.83
MHz.
The audio carrier is 4.5 MHz above the video carrier, so for TV Channel 2 it is 59.75 MHz.
The reason I mention all of this is that you have to be careful to note how a channel frequency is being specified. The two
common methods are