Tap Code Translator
Tap code sends each letter as two groups of knocks: the row, then the column, in a 5 by 5 grid of letters. It is slower than Morse but far easier to learn. Type text to get the taps, or taps to get the text.
Type text to get the taps, or type taps as pairs of numbers or groups of dots to get the text back. Play knocks it out loud.
The tap code grid
How tap code works
The alphabet is written in a 5 by 5 grid. K shares a square with C, so the grid has 25 squares. Each letter is two numbers: its row, then its column. H is row 2, column 3: two knocks, a short pause, three knocks. A longer pause separates letters. You only need to remember the first letter of each row, A F L Q V, and count along.
Tap code and Morse code
Morse is faster, but its short and long signals are hard to make by knocking on a wall or a pipe. Tap code needs only one kind of knock, so it works anywhere a sound can be made. By convention X separates sentences and K acknowledges a message.
History
The grid goes back to the Polybius square of ancient Greece, and a Cyrillic version is said to have been used by prisoners in Tsarist Russia. It is best known from the Vietnam War: in June 1965 four American prisoners in Hỏa Lò prison, the “Hanoi Hilton”, introduced it, and it became more widely used there than Morse because it was easier to teach.
Source
English Wikipedia, Tap code.
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