| 单词 | NMT 450 (Nordic Mobile Telephone 450 MHz) |
| 释义 | NMT 450 (Nordic Mobile Telephone 450 MHz) A 1G analog cellular radio technology developed and placed into service in the early 1980s in Scandinavian countries. NMT 450 operates in the 450 MHz band, employing frequency division multiple access (FDMA) to derive 200 channels with a width of 25 kHz. NMT 450 employs frequency division duplex (FDD) to achieve bidirectional communications, with the downlink in the 463–468 MHz band and the uplink in the 453–458 MHz band. Within each channel, frequency modulation (FM) is employed. See also 1G, analog, cellular radio, channel, downlink, FDD, FDMA, FM, and uplink. 74570c14.qxd 9/11/07 12:26 PM Page 338 |
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