CQ in Morse code

How to read it

ITU-R M.1172, the ITU’s list of abbreviations for the maritime radio service, defines CQ as a “General call to all stations”. ARRL’s glossary calls it “Calling any station”, the general call when requesting a conversation with anyone. ARRL says CQ came from the landline telegraph: the Marconi Company brought it into radio as a general call to all ships, other companies used KA, and the London Convention of 1912 adopted CQ as the international general call or “attention” signal.

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The rest of a call

ITU-R M.1677-1 sets the form of a call to a particular station: the call sign of the station wanted, not more than twice, the word DE, the caller’s own call sign, and the invitation to transmit, K (−·−). ARRL’s glossary gives DE as “from” or “this is” and K as “any station respond”. Both are among the Morse code abbreviations and Q codes (73, QTH, QSL).

KA, the older call

KA, the call the other companies used before 1912, is still in the ITU’s list as the “starting signal”, and ITU-R M.1677-1 gives the same signal, −·−·−, as the starting signal to precede every transmission.

CQ and CQD

CQD was a distress call, not a general call. White’s history of early radio says Marconi operators kept their company’s C.Q.D. for years after the 1906 convention set the international distress signal, SOS.