Convert Morse to ASCII

By ITU convention, the gap between elements (dot/dash) of one letter is one dot length. The gap between letters is three dot lengths. The gap between words is seven dot lengths. In text representation, that translates to: one space between letter codes, and three spaces (or / or |) between words. This tool detects all three conventions.

A prosign (procedural signal) is two or more letters sent without an inter-letter gap – so they read as one symbol. Common ones: AR (.-.-.) = end of message, SK (…-.-) = end of contact, BT (-…-) = break / new paragraph, KN (-.–.) = invitation to specific station, SOS (…—…) = international distress. When you toggle prosigns on, the decoder emits them as [AR], [SK], etc. instead of mistaking them for single characters.

Same Morse pattern, different intent. .-.-. is the standard ITU code for the plus sign (+), but it’s also the AR prosign meaning “end of message”. The tool needs to know which you want – flip the “Recognize prosigns” toggle. Without it, you get +. With it, you get [AR]. Other ambiguities: .-... is both & and AS; -...- is both = and BT.

Using the PARIS standard: at N words per minute, one dot lasts 1.2 / N seconds. So at 20 WPM, dot = 60 ms, dash = 180 ms, intra-character gap = 60 ms, inter-character gap = 180 ms, word gap = 420 ms. Frequency is 700 Hz (standard radio sidetone) with a small linear ramp at the start/end of each tone to avoid clicks. Output is 8 kHz mono 16-bit WAV.

Yes – switch direction. ASCII → Morse handles A-Z, 0-9, and 16 punctuation marks per ITU. Case is ignored (Morse is case-insensitive). Word separator in the output is your choice: 3 spaces (standard), /, |, or HTML   for use in web pages.

Not in the default 26-letter table. Some Continental Morse extensions support Ä (.-.-), Ö (—.), Ü (..–), and CJK kana via JIS / Wabun code – but they’re not part of ITU International Morse. Tokens that don’t match any pattern get the unknown-token treatment (mark / skip / angle-bracket).

You used a single space between SOS and HELLO. The decoder reads that as inter-letter spacing, not inter-word. Fix: insert / between the words, or use three+ spaces. So ... --- ... / .... . .-.. .-.. --- or ... --- ... .... . .-.. .-.. --- (three spaces) both yield SOS HELLO.

Yes – it’s a vanilla 16-bit PCM WAV with a standard 44-byte header. Plays in any music app, importable into any audio editor (Audacity, Reaper, GarageBand). Use it for amateur-radio practice, podcasts, Morse-training apps, or accessibility demos.

No. All decoding, encoding, and audio generation happens in your browser using vanilla JavaScript and the Audio API. Open DevTools → Network and confirm zero requests fire after the page loads – even when you Play or Download.

Yes. Total bundle is under 24 KB. Once loaded, disconnect and keep using – useful for field work or amateur-radio operating positions where internet may be unreliable.