CQ (call)
CQis a station code used bywirelessoperators derived from long established telegraphic practice on undersea cables and landlines, particularly used by those communicating inMorse code,(▄▄▄ ▄ ▄▄▄ ▄▄▄▄ ▄▄▄ ▄ ▄▄▄), but also by voice operators, to make a general call (called aCQ call). Transmitting the lettersCQon a particularradiofrequencymeans that the transmission is a broadcast or "General Call" to anyone listening, and when the operator sends "K" or says "Go Ahead" it is an invitation for any licensed radio station listening on that frequency to respond. Its use on radio matched the existing use on Morse landline telegraphy and dates from the earliest wireless stations. It was widely used in point-to-point diplomatic and press services, maritime, aviation, and police services until those services eliminated Morse radiotelegraphy. It is still widely used inamateur radiowhich still has active use of Morse radiotelegraphy.[1]
History and usage
[edit]The CQ station code was originally used by land line and undersea cable telegraphy operators in theUnited Kingdom.[2]An early land line reference to CQ is contained inElectrical Tables and Formulæ: For Use of Telegraph Inspectors and Operators(1871), which lists "The call for 'all stations' (C Q)...".[3]Additionally, in 1884 the telegraphic station code "CQ" was mentioned inThe Practical Telegraphist(1884), which lists "CQ all stations";[4]andThe Telegraphist(August 1884).[5]
International MorseCQwas adopted by theMarconi Companyin 1904 for use inwireless telegraphy,at that time viaspark-gap transmitters,and was adopted internationally at theLondon 1912 International Radiotelegraph Convention,and is still in use.[6]
A variant of theCQcall,CQD,was the first code used as a distress signal. It was proposed by the Marconi Company and adopted in 1904, but was replaced between 1906 and 1908 by theSOSprosign.When theTitanicsank in 1912, it initially transmitted the distress callCQD DE MGY(withMGYbeing the ship's call sign).Titanic's radio operator subsequently alternated betweenSOSandCQDcalls afterwards.[7]
Inamateur radiouse, aCQcall can be qualified by appending more letters, as inCQ DX(meaning "calling all stations located on a different continent from the caller" ), or theITUcall signprefix for a particular country (e.g.CQ VKfor "callingAustralia"orCQ JAfor "callingJapan"). The originator of the call is normally identified by appending the lettersDE(Frenchfor "from", also means "this is..." ) and the call sign of the transmitting station.[1]Another common qualifier isCQ TEST DE,followed by thesender's station ID,which is used inham radio contests.When usingCW mode,unattended receivers connected to a computer may automatically decode the signal and log it on theReverse Beacon Network.
In the use ofsingle-sideband (SSB)voice orCW mode(morse code telegraphy), an amateur radio operator often makes a general call by transmittingCQrepeatedly (such asCQ CQ CQ) so that other operators scanning for such calls are aided by the familiar rhythmic sound in quickly discriminating distant (weak signal) general callers from other traffic andspurious 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.[1][8]
The use of a CQ call is almost always used in single-sideband (SSB) voice or CW mode (morse code telegraphy). UnlikeFM 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 in constant use on theamateur bandsonshortwavebut very rarely used in theFMvoice mode of transmission or on FM repeaters common on theVHFandUHFlocal bands, since tuning of a repeater or FM signal does not require the aid of human perception to perfectly tune the signal.[1]
The code "dah dit dah dit, dah dah dit dah" (the vocalization of▄▄▄ ▄ ▄▄▄ ▄▄▄▄ ▄▄▄ ▄ ▄▄▄) was used as part of the chorus to the song "Communications" bySlim Gaillard.
See also
[edit]- CQ Amateur Radio,English-language magazine
- CQ ham radio,Japanese-language magazine
- Q codes
- Universal Postal Union
References
[edit]- ^abcdSessions, Ken W. (1974).How to be a Ham.G/L Tab Books.ISBN978-0-8306-4673-9.
Including latest FCC rules
- ^de Groot, Edward."R.M.S Titanic = MGY & other radio arcana".oceanliner.org.Ocean Liner Museum.Retrieved19 May2021.
- ^Clark, Latimer & Robert Sabine (1871)."Rules for Signalling".Electrical Tables and Formulæ: For Use of Telegraph Inspectors and Operators.London, UK: E. & F.N. Spon. p. 243.Retrieved16 January2024.
- ^Lynd, William (1884)."Alphabetical index to the official codes".The Practical Telegraphist and Guide to the Telegraph Service.London, UK: Wyman & Sons. p. 15.Retrieved10 September2023.
- ^Lynd, William, ed. (1 August 1884)."Ocean telegraphy: Introduction".The Telegraphist: A monthly journal of popular electrical science.Vol. 1, no. 9. p. 110.Retrieved10 September2023.
- ^Baarslag, Karl (1948).Famous Sea Rescues.Grosset & Dunlap.
Formerly titled:SOS to the Rescue
- ^Campbell, Ballard C. (2008).Disasters, Accidents, and Crises in American History: A reference guide to the nation's most catastrophic events.Infobase Publishing. p. 3 ff.ISBN978-1-4381-3012-5.
- ^Betts, Alan (2002).Foundation Licence Now.Potters Bar, UK: Radio Society of Great Britain. p. 23 ff.ISBN978-1-872309-80-4.
General references
[edit]- Straw, R Dean, ed. (October 2005).The ARRL Handbook for Radio Communications 2006(83rd ed.). Newington, CT: American Radio Relay League.ISBN0-87259-949-3.OCLC62026192.
- Bergquist, Carl J (2001-05-01).Ham Radio Operator's Guide(2nd ed.). Indianapolis: Prompt Publications.ISBN0-7906-1238-0.OCLC47051066.
- Dennison, Mike; Chris Lorek, eds. (June 2005).Radio Communication Handbook(8th ed.). Potters Bar, Hertfordshire, England: Radio Society of Great Britain.ISBN1-905086-08-3.OCLC123027893.
- Commercial Traffic Regulations, 1915.Government Printing Office, Washington, DC: United States Naval Radio Service.