Translator
Type in either box; the other updates live. Play it to hear the rhythm and watch the timeline.
Dot / dash timeline
Playback settings
The actual dot and dash speed.
Overall speed; slows the gaps, not the letters.
Koch trainer
Learn two characters at full speed
Each round plays a short group built from the characters you have unlocked, sent at full character speed. Type what you hear. Hold 90% accuracy across a round and the next character unlocks.
Listening...
Per-character accuracy
Built from every Koch trainer round you have run. Darker and redder means more misses.
No accuracy data yet. Run a Koch trainer round to see it here.
Straight-key practice
Hold the spacebar, or press and hold the pad below, to key. Release to send the next element. Finish to decode your timing.
Hold spacebar or press here to key
Decoded text
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-Dit:dah ratio (ideal 3.0)
-Spacing consistency
Reference chart
Code tree
Each branch is a dit to the left, a dah to the right.
Letters and digits
Prosigns
Common Q-codes
Flash mode
Encodes text to a screen flash. Tries the device torch first where the browser supports it.