| 单词 | cordless telephone |
| 释义 | cordless telephone A system comprising one or more telephone handsets that connect on a wireless radio frequency (RF) basis to a base station that connects via a standard plug and jack for access to the public switched telephone network (PSTN). The original cordless telephones (circa 1980) in the United States were assigned one of 10 channels in the 27 MHz range. In 1986, the Federal Communications Commission (FCC) changed the cordless frequency range to the 46 and 49 MHz bands and reduced the allowable power levels. Contemporary digital versions operate in the 900 MHz, 2.4 GHz, and 5.8 GHz bands, which are in the unlicensed industrial/scientific/medical (ISM) band. Contemporary standards include Cordless Telephony generation 1 (CT1), Cordless Telephony generation 1 plus (CT1+), Cordless Telephony generation 2 (CT2), Cordless Telephony generation2 plus (CT2+), Cordless Telephony generation 3 (CT3), Digital Enhanced (nee European) Cordless Telecommunications (DECT), Personal Handyphone System (PHS), Personal Access Communications Services (PACS), Personal Communications Services (PCS), and Personal Wireless Telecommunications (PWT). The cordless telephone was invented by Al Gross, who also invented the CB radio, paging system, and walkie talkie. See Gross, Al. See also CB radio service, CT1, CT1+, CT2, CT2+, CT3, DECT, FCC, ISM, jack, PACS, paging system, PCS, PHS, plug, PSTN, PWT, RF, walkie talkie, and wireless. |
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