SOS as sent
Text
SOS
Morse
... --- ...
Three dots, three dashes, three dots. At 20 words per minute the whole sign lasts about one and a half seconds - at 5 WPM, about six.
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SOS in Morse Code
··· −−− ··· - the translator opens on the distress signal. Press Play to hear it, switch on Flash light to signal it with your screen.
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What is SOS in Morse code?
In Morse code SOS is written ... --- .... As three separate letters that would be S (...), O (---) and S (...), but a distress call is sent as a single prosign - nine symbols with only the one-unit gaps between them, no letter gaps - which is why it is sometimes written with a bar over it. Above, the translator writes it as three letters so you can see the parts; the sound is the same pattern either way.
The signal was adopted at the 1906 Berlin radiotelegraph convention and became the worldwide standard in 1908. It replaced the Marconi company's CQD and won because of its rhythm: three short, three long, three short is unmistakable through static, at any speed, to an operator who knows no other Morse at all. It was never an abbreviation - the readings "Save Our Souls" and "Save Our Ship" were invented afterwards to help people remember it.
Press Play to hear SOS at the speed on the slider, turn on Flash light to signal it with a phone screen (dark for the gaps, bright for the symbols), or download it as a .wav. Type anything else in the box and the page becomes the ordinary translator again.
What to know about the SOS signal
- SOS is
... --- .... Nine symbols, and as a distress call there is no letter gap between the S, the O and the S - it is one sign. - It means nothing. "Save Our Souls" is a mnemonic added after the fact; the signal was chosen for its rhythm, not its letters.
- Sound is not the only way to send it: three short, three long, three short works with a torch, a whistle, a car horn or by tapping on a pipe.
- In light,
SOScan also be written out visually - three short flashes, three long, three short - and the Flash light option above does exactly that. - The voice equivalent on a radio is "Mayday", said three times; SOS belongs to Morse and to visual signals.
SOS and the other distress signals
The signal SOS replaced
Text
CQD
Morse
-.-. --.- -..
CQ was the general call to all stations and D was added for distress. Titanic's operators sent both CQD and SOS in 1912; SOS was still new.
A distress message with a position
Text
SOS SOS SOS DE CODDY 51N 30W
Morse
... --- ... / ... --- ... / ... --- ... / -.. . / -.-. --- -.. -.. -.-- / ..... .---- -. / ...-- ----- .--
The traditional form: the sign three times, DE ("from") and the sender's name, then the position. Paste it into the translator and play it.
Mistakes people make with SOS
- Sending it as three separate letters with full letter gaps. It still reads as SOS, but the real distress sign is continuous - practise it as one rhythm.
- Reading it as O-S-O by starting in the middle. A run of dashes between dots is always the O of SOS; three dashes first means you missed the start.
- Flashing it too fast to be seen. A light signal needs a slower pace than sound - around one flash per second for the dots, three seconds for the dashes.
- Thinking a smartphone SOS setting sends Morse. The emergency SOS feature on phones calls a number; the Morse signal is for when there is no network.
SOS in Morse code FAQ
What does SOS stand for?
Nothing. It was chosen at the 1906 radiotelegraph convention because three dots, three dashes, three dots is simple to send and impossible to confuse. "Save Our Souls" and "Save Our Ship" are backronyms people made up later to remember it by.
How do you send SOS with a flashlight?
Three short flashes, three long flashes, three short flashes, then a pause, and repeat. Keep the long flashes about three times the length of the short ones. Turn on Flash light above and press Play to see the rhythm - the pane goes bright for each symbol.
How long does SOS take to send in Morse code?
The sign is 27 units long (dots of 1, dashes of 3, gaps of 1 inside each letter, 3 between letters). At 20 words per minute a unit is 60 milliseconds, so about 1.6 seconds; at 5 WPM about 6.5 seconds. Drag the Speed slider to hear the difference.
Is SOS still used today?
Morse SOS stopped being the official maritime distress signal in 1999, when ships moved to the satellite-based GMDSS system. It is still universally recognised, still taught, and still works as a visual and sound signal anywhere there is no radio.
What is the difference between SOS and Mayday?
SOS is the Morse and visual distress signal. Mayday is its spoken equivalent on voice radio, from the French "m'aider" (help me), always said three times. Both mean grave and imminent danger to life; for urgency without immediate danger the spoken signal is Pan-pan.
