Morse Code Translator

How the Morse Code Translator works

Morse code encodes each character as a sequence of short and long signals — dots and dashes, or more properly dits and dahs. Samuel Morse and Alfred Vail built the first version for the electric telegraph, and the line from Washington to Baltimore carried "What hath God wrought" in 1844. The American code was later reworked in Germany into the simpler Continental code, which the International Telegraph Convention adopted in 1865. That International Morse Code is the one in use today, and its current definition is ITU-R Recommendation M.1677.

Why a Morse code translator still earns its keep

Morse survives because it gets through where nothing else does. A single on-off tone occupies a few tens of hertz of bandwidth, so a weak signal that would be lost as speech can still be read by ear under heavy noise. Ships relied on it until the Global Maritime Distress and Safety System replaced it in 1999, and the United States stopped requiring it for amateur radio licences only in 2007. It is still in daily use today:

• Aviation. VOR and NDB radio beacons transmit a two- or three-letter identifier in Morse so a pilot can confirm the right station is tuned before trusting it for navigation.
• Amateur radio. CW (continuous wave) remains a favourite mode for low-power and long-distance contacts, and contest operators send it at thirty words per minute or more.
• Accessibility. Morse input is built into some phone keyboards, letting people with very limited movement type with one or two switches.
• Signalling in a pinch. A torch, a whistle or a tapped pipe can all carry it. In 1966 a prisoner of war, Jeremiah Denton, blinked T-O-R-T-U-R-E in Morse during a filmed propaganda interview.

The timing is the code

In a real transmission a dash is three times the length of a dot, the gap between the parts of one letter is one dot long, the gap between letters is three dots, and the gap between words is seven. Speed is measured against the word PARIS, which takes exactly fifty dot units including its trailing gap, so a dot lasts 1,200 ÷ WPM milliseconds: 60 ms at 20 words per minute.

Written down, that structure survives as a single space between letters and a longer break between words. That's why the word separator matters: .... ../.--- --- . and .... .. .--- --- . say the same thing, and both conventions are common. The decoder accepts either.

What it covers

All twenty-six letters, the digits nought to nine, and the punctuation the standard defines — full stop, comma, question mark, apostrophe, exclamation mark, slash, brackets, ampersand, colon, semicolon, equals, plus, hyphen, underscore, quotation mark and the at sign, which was added in 2004 for email addresses. Morse has no upper and lower case, so decoded text comes back in capitals and case is discarded on the way in. Anything with no defined code is dropped rather than guessed at, and when decoding, the codes that were dropped are listed under Not decoded.

People write dots and dashes with whatever their keyboard offers — a bullet for a dot, an en dash or an underscore for a dash. Those are normalised before decoding, so a Morse string copied out of a book or a forum post usually just works.

... --- ... is SOS, adopted in 1906 because it is unmistakable, not because it stands for anything. .-.-. is the end-of-message prosign and ...-.- signs off. Prosigns run together without letter gaps in real use, which is why decoding them here gives you letters rather than the prosign.

Tips and pitfalls

• Spaces carry meaning. Without letter gaps, ... could be S, EEE, IE or EI. If a decode looks like nonsense, check the spacing first: missing or doubled spaces are the most common fault.
• Learn it by sound, not by chart. Operators who memorise dots and dashes visually hit a wall around ten words per minute because they are counting. The Koch method teaches characters at full speed from day one, and Farnsworth timing stretches the gaps rather than the characters so the rhythm of each letter stays intact.
• Short letters are the common ones. E is a single dot and T a single dash because Vail sized the code by counting type in a printer's case. Once you know that, the alphabet stops looking random.

Decoding from audio

Upload a recording — WAV, MP3, OGG or anything else the browser can play — and the tool measures the loudness of the signal every five milliseconds, decides where the tone is on and off, and sorts the on-periods into dots and dashes by their length. The shortest cluster of tones sets the dot length. Gaps under two dots sit inside a letter, gaps under five separate letters, and anything longer is a word break. The recording never leaves your browser.

How to read the result

Under an audio decode you get the "Morse heard" line and a speed in words per minute. Read the Morse line before trusting the text. If whole words have merged, the sender's word gaps were short. If letters split into pairs of Es and Ts, the keying was uneven and the dot length was set too small. Clean, evenly keyed audio from a practice oscillator or keyer decodes reliably. A hand-keyed recording with wandering timing or heavy background noise may come back with a few wrong letters, and the Morse line shows exactly where.

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