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CQD and SOS The distress signal CQD originated from the signal CQ, expressing "seeking you," or "all stations." The signal CQ was commonly used among wireless operators -- and land-based telegraphers before them -- as a time-saving means of addressing all stations from one signal. The ability of CQ to convey distress was eventually diminished by frequent use. Therefore, in 1904 Guglielmo Marconi's wireless company announced the distress signal CQD would be used, signifying "Seeking you. Distress!" Or, "All stations. Distress!"

However, while British wireless operators favored the CQD as their distress signal, the signal was not used universally. The Germans used SOE. The Americans used NC, which meant "call for help without delay." Each of these signals was sent as a sequence of distinct letters, with brief spaces in between. In an effort to achieve a faster and more attention-grabbing signal, delegates at the second International Radio Telegraphic Conference, held in Berlin in 1906, suggested a simpler signal -- SOS, which would be sent as a continuous stream,...---..., instead of a sequence of letters. By 1908 this proposal was ratified by all conference members except the United States.

Although the U.S. lagged in adopting the new signal, the first SOS was transmitted from the American vessel "Arapahoe" in 1909, after a propeller shaft snapped. But CQD remained popular-primarily with the British. Wireless operator Jack Binns used CQD signals to save the sinking "Republic" in 1909. In 1912 the wireless operators aboard the "Titanic," Harold Bride and Jack Phillips, called for help using both SOS and CQD distress signals.

After the sinking of the "Titanic," the United States officially adopted the SOS as its distress signal. The use of SOS soon became universal, and the standard signal ruled the high seas until early 1999. Then, in an agreement engineered by the United Nations, Morse Code itself was officially retired as a method of marine communication. Its replacement, the Global Maritime Distress and Safety System, relies on a system of satellites to relay distress signals.

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