signal) general callers from other traffic and spurious emissions. This technique allows the other operators to zero-in as close to the caller's center frequency using the human ear to fine-tune their transceiver before engaging the caller in a two-way communication. The use of a CQ call is almost always used in single-sideband (SSB) voice or CW mode (morse code telegraphy). Unlike FM mode, in the SSB voice and CW mode areas of the amateur radio bands operators are free to center their transmissions where it is most optimal (such as away from adjacent traffic that can interfere) and not expected to use whole-number, divisible-by-five, or otherwise channelized center frequencies. CQ is constantly used on the HF shortwave amateur bands but very rarely used in the FM voice mode of transmission or on FM repeaters common on the VHF and UHF local bands since tuning of a repeater or FM signal does not require the aid of human perception to perfectly tune the signal. The code was used as part of the chorus to the song "Communications" by Slim Gaillard. See also Amateur radio CQ Amateur Radio, English-language magazine CQ ham radio'', Japanese-language magazine Q codes Universal Postal Union References General references Amateur radio Morse code Radio communications Operating signals