Morse decoder and CW practice audio in the browser
Signal-Pirat decodes Morse code (CW) right in the browser – from a WAV or MP3 file or live via microphone or receiver output. It also plays text as Morse audio and saves it as WAV. Nothing to install, nothing leaves the browser.
Open in the browser
No installation, no sign-up needed.
What the page does
- Decode Morse from a recording; the pitch is detected automatically
- Live decoding via microphone or receiver output
- Play text as Morse and save it as WAV
- Farnsworth timing: fast characters, slower spacing – for learning by ear
- Error-free in test runs from 10 to 35 WpM from about 3 dB SNR
Background
Morse characters consist of dots and dashes in a 1 : 3 ratio, separated by gaps of 1, 3 and 7 dot units. The dot length in milliseconds is 1200 divided by the speed in words per minute (standard word PARIS). The decoder measures the tone with the Goertzel algorithm, separates keying and gaps and classifies the gaps by their distribution – so Farnsworth timing and long pauses are read correctly.
In practice
How it works: tune the receiver to a CW signal, set the pitch to about 600 to 800 Hz and connect the audio output to the computer; a microphone in front of the speaker will do in a pinch. A narrow CW filter in the receiver improves results considerably. If you are learning Morse, start with characters at 20 WpM and wide spacing and gradually shorten the spacing.
Frequently asked questions
Does the Morse decoder work on a smartphone?
Yes, in current browsers with microphone access. Best with a single clean CW signal.
Which speeds are recognised?
Error-free in test runs from 10 to 35 words per minute; hand keying with strongly varying speed causes more errors.