North American Cable Television Frequencies
In North American cable TV networks, the radio frequencies used to carry signals to the customer are allocated to standardarized channel numbers listed in the CEA standard 542. Cable channel frequencies are generally different from off-air broadcast frequencies. Since the cable network is a closed system, frequencies used for over-the-air services such as mobile radio, cellular telephone, or aircraft communications can be assigned to carry television programming. The assignment of channel frequencies must on the one hand reduce the effects of distortion and mutual intereference generated within the cable television distribution system, and on the other hand maintain compatibility with the customer's connected equipment.
Slight frequency offsets are applied in some systems so that any signal leakage out of the cable distribution plant is less likely to cause objectionable interference to over-the-air users of the same frequencies.
Read more about North American Cable Television Frequencies: Harmonically Related Carriers (HRC), Incrementally-related Carriers (IRC), North America Cable Television Frequencies, Channel Usage, Digital Cable Channels
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