CQD established as international radio distress signal

In 1904, the Marconi Company established “CQD” as the first international radio distress signal. The signal “CQD” was derived from the general call “CQ,” used to alert all stations, with the addition of “D” to signify “distress.” This signal was intended to be universally recognized by ships and shore stations equipped with wireless telegraphy, ensuring a standardized method for indicating emergencies at sea. However, “CQD” was later supplanted by the more distinct and universally recognized “SOS” signal in 1906, following the International Radiotelegraph Convention. Despite its relatively short period of use, “CQD” played a crucial role in the early development of maritime distress signaling protocols.