Morse Code Error Simulator
One transmission, one deliberate fault. Your job is not to copy the text but to say what is wrong with it.
Which fault was that?
Play it, then pick the fault. The clean version is one button away if you need the comparison, and both timelines are drawn underneath.
Why naming it is the point
Hearing that something is wrong takes a week. Saying what is wrong takes longer, and it is the part that is worth anything.
On the air it turns a vague complaint into a request. "You are hard to copy" tells the other operator nothing. "Your dashes are short" tells them exactly what to change, and they usually can - most sending faults are habits, not limits.
It also works on your own hand. You cannot fix a fault you cannot name.
The six faults
Each round contains exactly one of these, and nothing else is altered. That is deliberate: two faults at once and you learn to name neither.
- Dashes too short. The most common fault of all. A dash at twice a dot instead of three times starts sounding like a dot, and whole letters flip.
- Dashes too long. Rarer, and much less damaging - a long dash is still unmistakably a dash. It only costs time.
- Dots uneven. The dots vary in length. Nothing is individually wrong, but the ear loses its reference for what a short element is.
- Letter gaps too short. The dangerous one. Letters run together into a different letter - often a real one, so the result reads plausibly and is wrong.
- Letter gaps too long. Sounds hesitant, costs time, and is otherwise harmless. Beginners do this and should not be talked out of it too early.
- Speed drifts. Not jitter but a slow wander across the transmission. Hard to catch on a short word, which is why it is the one most people miss here.
Right quantity, wrong direction
Answering "dashes too long" when they were too short counts as a near miss, not a wrong answer. That is not generosity - it is a different state of knowledge.
Someone who says "the dashes" has identified the quantity that is off and only mixed up the sign. Someone who says "the gaps" has not heard the fault at all. Scoring those the same would hide the more useful information, which is how far along you actually are.
Near misses count half in the tally.
The numbers under the answer
After each round two figures appear: the worst deviation and the average one, both measured against the clean version of the same word.
They are worth watching over several rounds. A fault at 15 per cent average deviation is audible to a trained ear and invisible to a new one; at 40 per cent almost anyone hears that something is off, even if they cannot say what. If you are getting the 40s and missing the 15s, that is not a gap in knowledge but in listening time.
Frequently asked questions
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Do I need to copy the text?
No. The text is shown after you answer. The question is what is wrong with the sending, not what it says.
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Why only one fault at a time?
Because two faults at once teach you to name neither. Every other quantity is held exactly at the norm, so what you hear can only be the one thing.
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Which fault should I worry about in my own sending?
Short dashes and short letter gaps. The other four cost time or sound untidy; those two produce the wrong letters. The sending practice measures both in what you actually send.