Morse code translator you can hear

It is three letters on paper and one unbroken sound on the air. Spelled out as separate letters, S O S is ... --- ... with a gap after each one; as the distress call it is run together into a single nine-element symbol, ...---..., with no letter gaps at all, which is why it is properly written with a bar across the top. This page does both: type SOS and you get the three separate letters, type <SOS> and you get the run-together call. The letters were adopted internationally in 1908 because that pattern is unmistakable at speed and hard to mishear — Save Our Souls was invented by the public afterwards.

No — there is nothing in the code that distinguishes a capital from a small letter. Dash-dot-dash-dot is C whether you meant C or c, so every translator, this one included, hands decoded messages back in capitals. It also means case is the one thing a round trip cannot preserve: send Hello World, decode it again, and you get HELLO WORLD — identical in Morse, different on the page.

20 WPM is 100 characters a minute, built on a dot that lasts 60 milliseconds. Speed is measured against the word PARIS, which comes to exactly 50 units of time including the gap that follows it, so one unit is 1,200 divided by the speed in milliseconds: 240 ms at 5 WPM, 60 ms at 20, 30 ms at 40. A whole letter H at 20 WPM takes 420 ms. Beginners read comfortably at 5 to 13 WPM, most amateur radio conversation happens between 15 and 25, and contest operators work at 30 to 40, where the same H goes by in a fifth of a second.

Because the alphabet was fixed for a 19th-century telegraph and has barely moved since — the last character it gained was the @ sign, added by the ITU in 2004 so email addresses could be sent over the air. Emoji, the degree sign, curly brackets and the rest have no code, so this translator lists them under the panel instead of inventing one. Accented Latin letters are folded onto their plain forms, so café is sent as CAFE: codes do exist for ä, é, ñ, ö and ü, but they are national additions rather than part of the international standard, and an operator outside those countries would not recognise them.

Nine times in ten it is the spacing. Morse needs one space between letters and a wider gap between words, and a run like ...---... with no spaces anywhere could be SOS or half a dozen other readings, so a translator has nothing to cut on. Put single spaces between letters and a slash, a pipe or three spaces between words and it will decode. Anything that still matches no character comes back inside square brackets with the group intact, so you can see exactly which one failed — usually a sixth element that should not be there, or a dash your word processor turned into an em dash. This page accepts em dashes, en dashes, underscores and bullet dots as dashes and dots and converts them for you.

Yes, and the Farnsworth switch is the part that makes it work. Learning at a genuinely slow speed teaches you to count dots, a habit that stalls around 10 words a minute and then has to be painfully unlearned; Farnsworth timing, named after the operator whose method the ARRL code courses adopted, sends every letter at a brisk 18 WPM so you learn its rhythm as one sound, and buys the slower overall pace out of the silences instead. At an overall 5 WPM with Farnsworth on, a dot lasts 67 ms rather than 240 ms and you get 1.6 seconds after each letter to name it before the next one starts.

No — the translation, the tone and the flash all happen inside this browser tab. Dots and dashes are looked up in a table held in the page itself, and the sound is generated by your browser rather than fetched as an audio file, so neither your words nor the code is uploaded, logged or stored. After that first load nothing more is fetched, so practising somewhere without a signal works exactly as well.