GUIDES AND REFERENCES
Morse Code Audio Decoding Guide
Follow a clean recorded-signal example from tones to marks and letters. Automatic file decoding is not available on this page.
From a recording to a character
A decoder first separates a tone from background sound, detects intervals where it is present, then classifies their durations. A dot is one unit and a dash three. The off intervals distinguish marks, letters and words. A correct tone detector alone cannot determine where a word ends.
Consider A at 20 WPM and 600 Hz: sound from 0 to 60 ms, silence from 60 to 120 ms, then sound from 120 to 300 ms. That on/off/on sequence becomes the two-mark dot-dash pattern for A. If the middle silence were 180 ms instead, the same marks would be E followed by T. The table makes the classification explicit.
A reproducible clean-signal exercise
Open the main translator, enter A in International mode, set 20 WPM and 600 Hz, and download WAV. Repeat with ET. Listen to both and compare the gap. These generated files are controlled examples: they help explain what a recording decoder must detect, without pretending that this page scans them.
For an existing recording, retain the original and note likely pitch, background noise, clipped starts and changes of speed. Filtering around the desired tone can help, but another signal on the same frequency and weak or irregular marks remain difficult. An automatic result needs checking against the recording, especially when a plausible word hides an uncertain character.
Which job this site performs
The main tool decodes written dot/dash groups and generates audio. Voice input transcribes spoken words through the browser; it does not recognize Morse tones. This page has no recording upload or automatic decoding engine. For actual signal analysis, the linked experimental decoder is a separate website with its own controls and policies.
A at 20 WPM: envelope trace
| Time interval | Tone state | Interpretation |
|---|---|---|
| 0–60 ms | On | One-unit dot |
| 60–120 ms | Off | One-unit gap inside A |
| 120–300 ms | On | Three-unit dash |
| 300 ms | End | Complete A (.−) |
Worked examples
These patterns use International Morse. Spaces separate letters; / separates words. A slash in the original text is encoded as -..-.
- A
- Try this message
.-0.30 seconds at 20 WPM - ET
- Try this message
. -0.42 seconds at 20 WPM