Morse Code Translator

A dot, a dash, and silence. What makes Morse harder than a substitution cipher is that the silence carries as much meaning as the sound, and all of it is measured against one unit that never appears on its own.

Timing is the whole thing

dot                 1 unit of sound
dash                3 units of sound
gap inside a letter 1 unit of silence
gap between letters 3 units of silence
gap between words   7 units of silence

Everything is measured in that one unit. Shrink it and
the whole message speeds up in proportion.

Get the ratios wrong and a fluent operator cannot read it, even though every dot and dash is correct. Send the letter gaps too short and words run together. Send them too long and the receiver hears separate letters instead of a word.

Why speed is quoted against PARIS

P     A    R    I  S
.--.  .-   .-.  .. ...

31 units of letters
19 units of gaps
50 units in total, counting the word gap at the end

At 20 words a minute, PARIS goes out twenty times, so
one unit is 60 milliseconds.

Words per minute needs a word to count, and different words take different times to send. PARIS was picked because it comes to exactly fifty units including the gap after it, which makes the arithmetic trivial: one unit in milliseconds is 1200 divided by the speed.

The other standard is CODEX, at sixty units, used mostly for teleprinter speeds. A message quoted in one and sent at the other is out by twenty per cent.

Farnsworth spacing

Learning Morse at five words a minute teaches you to count dots, and that habit stops you ever getting past about ten. The fix, worked out at the ARRL in the 1950s, is to send each letter at full speed and stretch only the gaps between them.

The two sliders above do exactly that. Put the character speed at 18 and the overall at 5 and you hear real letter rhythm with time to think in between. Set them the same and you get ordinary timing.

SOS is not three letters

... --- ...

Sent as one run, with no letter gaps in it. Written as
three letters it would be S O S with pauses, which is
not the same signal and does not sound like it either.

SOS is a prosign, sent as one continuous run. It was chosen in 1906 for being unmistakable and easy to send under pressure, not because it stands for anything. Save Our Souls came afterwards.

Several prosigns share a pattern with a punctuation mark, so the same dots and dashes mean different things depending on context. BT and the equals sign are identical, as are AR and plus, and AS and ampersand. There is no way to tell them apart from the signal alone.

What is actually standard

ITU-R M.1677-1 covers the letters, the digits and a short list of punctuation. Everything else is convention. The accented letters vary by country, the dollar sign is an American addition, and the at sign was only added in 2004, which makes it the newest character in a code from 1865.

Reading here is deliberately relaxed about how the marks are typed. Middle dots, bullets, underscores, en dashes, minus signs and pipes are all understood, because people paste Morse from wherever they found it.

Where the gaps go when it is written down

Two conventions are common: a slash between words, or one space between letters and three between words. Both are read here. When there is no slash, the shortest run of spaces in the message is taken as the letter gap and anything longer as a word gap, so a message padded out for legibility does not come back as a string of single letters.

It is still in use

Aviation and marine beacons still identify themselves in Morse, which is why a pilot tuning a VOR listens for three letters before trusting it. Amateur radio uses it because a human ear can pull a tone out of noise that would swallow speech entirely.

It also survives as an accessibility input. Somebody who can operate one switch can send anything, which is a property no keyboard has.