| 单词 | guard band |
| 释义 | guard band A frequency band that exists between two information-bearing channels, a guard band pro- vides channel separation in order to avoid mutual interference.Analog voice grade bandwidth, for example, is defined as 4,000 Hz (4 kHz). As illustrated in Figure G-2, the voice signal runs in the 300–3,300 Hz range, and signaling and control functions take place in the 3,300–3,700 Hz range. The 0–300 Hz range and the 3,700–4,000 Hz range are used as guard bands. These guard bands prevent mutual interference between voice channels when multiplexed using frequency division multiplexing (FDM). Guard bands are equally important in video communications.An analog community antenna television (CATV, aka cable TV) video channel has a width of approximately 6,000,000 Hz, or 6 MHz, of which approximately 4.5 MHz is used for transmission of the video signal.The balance of the bandwidth is used for guard bands, also known as transition bands in this context, to separate adjacent channels riding the common, analog coaxial cable system. See also bandwidth, CATV, channel, FDM, frequency band, interference, MUX, and voice grade. 4,000 Hz Guardband 3,700 Hz Signaling & Control 3,300 Hz Voice 300 Hz Guardband 0 Hz |
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