SOS

SOS, code letters of the international distress signal. The signal is expressed in International Morse code as … — — — … (three dots, three dashes, three dots). This combination was established by the International Radiotelegraphic Convention at Berlin in 1906. The letters (SOS) do not refer to any words but were selected because they are easy to transmit. The use of Morse code for sending distress calls is now superseded by automated systems using satellite relay; the U.S. Coast Guard no longer monitors Morse code transmissions. The distress code by radiotelephony is MAY DAY, which corresponds to the French "m'aider." The signal NC, not followed by a message, also has the same meaning.

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

More on SOS from Fact Monster:

  • Ferdinand of Aragon - Biography of Ferdinand of Aragon, One-half of Ferdinand and Isabella
  • This Day in History: August 11 - August 11 1909 Arapahoe became the first American ship to use the S.O.S. distress signal. 1934 The ...
  • Nick Jonas - Biography of Nick Jonas, Teenage lead singer for the Jonas Brothers band
  • Samuel F. B. Morse - Biography of Samuel F. B. Morse, The telegraphic pioneer who invented Morse Code
  • Rihanna - Biography of Rihanna, Singer of the hit single "Umbrella"

See more Encyclopedia articles on: Technology: Terms and Concepts