SOS: what is it and how is it decoded

We also use the word SOS in ordinary speech. This is a signal that you need help. It’s no secret that SOS is the distress sign originally used on ships. That’s just how it appeared and why these three letters were chosen, and what alternative they have in general – remains a mystery to most. In this article we will talk about the history of the appearance of the famous signals for help.

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The history of navigation is calculated for centuries and even millennia. But initially, the methods of signaling were exclusively visual and audible. You can mention a variety of flags, signal lights or the sound of bells. The sailors even tried to report the shipwreck using bottle mail, but the effectiveness of such a means of communication was frankly low. Information reached the right people when there was no point in helping the wrecked.

But at the end of the 19th century, such a useful invention as radio received practical application. The parties used Morse code to communicate, but the developed competition between radiotelegraph companies forced them to form some common standards. It was especially important to highlight the distress signal so that it was understandable to everyone.

It took several years to approve the standard. At the First International Radiotelegraph Conference, held in Berlin in 1903, the need for the priority of a distress signal was recorded, but he himself was not identified. The Marconi company, meanwhile, introduced its own code – CQD ( – · – · – – · – – · · ). The first two characters carried out a general call to all stations ( – · – · – – · -), and the letter D ( – · ·), obviously, had a reference to “danger” – danger. However, ships with radios from other manufacturers used excellent options or simply texted about problems, asking for help.

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How did the SOS signal come about?

How did the SOS signal come about?

In 1906, the Second International Radiotelegraph Conference took place in Berlin. The main issue at it was the approval of a universal signal for help. The American representatives did not like the Marconi option, because similar signals were used on the coast, on the railways. As a result, it was decided to take as a basis the version of the German company Telefunken (Telefunken). Her additional signals were not similar to the letters of the Morse code, they did not have letter spacing, and the emphasis was on a large number of characters. The Notzeichen signal had as many as nine characters: three dots, three dashes, three dots (. . . — — — . . .). This made it possible to explicitly distinguish it from the general flow. And the symmetrical structure was convenient for recognition and memorization. The signal did not receive a letter name, the conference only designated it and the procedure for actions in case of receipt. On October 3, 1906, a single distress signal was approved, which became widely known as SOS.

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How does the abbreviation SOS stand for?

Initially, the signal was not associated with letters, but such a sequence corresponds to the SOS combination in Morse code. True, there is no pause between letters when transmitting. The letter combination “SOS”, associated with a distress signal, is arbitrarily chosen from several possible alphabetic or alphanumeric sequences from which this nine-character signal can be composed, because this sequence is easy to remember. Later, on the basis of three letters, they began to build word combinations corresponding to their spirit: “Save Our Souls” (save our souls) or “Swim Or Sink” (swim or drown), Stop Other Signals (stop other signals). Russian sailors began to use the following decoding: Save From Death.

According to legend, the first SOS signal sounded from the sinking Titanic in 1912. In fact, this was at least the eighth use of the signal.

How does the abbreviation SOS stand for?

The first SOS was filed in 1909 by the ship “Arapaho”, which lost its course off the east coast of North America. The signal was received by a station in North Carolina and passed on to the shipping company. And although since February 1, 1999, ships began to use a new, more advanced distress signal system, GMDSS, the SOS signal is still used, although much less often. The new automatic system makes it possible to send a distress signal even to a non-professional, and the “panic button” can be placed not only in the radio room, but anywhere on the ship.

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What does SOS mean in a phone?

Emergency call - SOS on iPhone.  How to make a call?

In many phones, for example, the iPhone (Apple Watch), it is possible to send an SOS signal – to make an emergency call to the rescue service (detailed).


But in voice communication using the radio, a different signal is used – Mayday. It is used in situations where the life of a person or people is in danger. It can be a crash not only of a ship, but also of an aircraft, as well as fires, explosions. And so that the signal is not confused with some similar one, it is transmitted three times in a row.

The history of the appearance of the Mayday signal is connected with aviation. The author of the idea is known – this is the senior radio operator of London’s Croydon Airport, Frederick Stanley Mockford. He was given the task of coming up with a signal that is easily understandable and distinguishable even in conditions of poor communication, which would be difficult to confuse with other messages. The phrase May Day is an English transcription of the French word m’aidez, which is a compact version of the phrase venez m’ader (help me). This choice was understandable – aircraft from Croydon flew mainly to Le Bourget, Paris. The phrase was clear to both the British and the French. It was put into circulation in 1923. Although there are dedicated distress frequencies, Mayday can be transmitted on any frequency.

There are signals for emergencies, but not carrying an immediate threat to people’s lives. For example, Pan-Pan, derived from the French word panne or “breakage”. This signal is classified as “urgency”. It can also be found on voice radio. Pan-pan speaks of some kind of emergency on a vehicle with a danger to passengers, but without an immediate threat to their lives. For example, a ship has problems with the engine – this is the reason for the Pan-pan signal. If a strong leak has opened and the ship is about to sink, then Mayday should be signaled. If earlier in such a situation a signal was sent using radiotelegraphy in the form of three dots, three dashes and three dots, today you can use GMDSS by simply pressing a special button.

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