Design
The tap code is based on a Polybius square, a 5×5 grid of letters representing all the letters of the Latin alphabet, except for K, which is represented by C. Each letter is communicated by tapping two numbers: the first designating the row (horizontally) and the second designating the column (vertically). The letter "X" is used to break up sentences. The tap code requires the listener to only discriminate the timing of the taps to isolate letters. For example, to specify the letter "A", one taps once, pauses, and then taps once again.
Or to communicate the word "water", the cipher would be the following (the pause between each number in a pair is smaller than the pause between one pair and the next):
| W | A | T | E | R |
|---|---|---|---|---|
|
5, 2 |
1, 1 |
4, 4 |
1, 5 |
4, 2 |
|
····· ·· |
· · |
···· ···· |
· ····· |
···· ·· |
Because of the difficulty and length of time required for specifying a single letter, prisoners often devise abbreviations and acronyms for common items or phrases, such as "GN" for Good night, or "GBU" for God bless you.
By comparison, Morse code is harder to send by tapping or banging because it requires the ability to create two differently sounding taps (representing the dits and dahs of Morse code). A Morse code novice would also need to keep a "cheat sheet" until he or she remembers every letter's code, which the captors would likely confiscate. Tap code can be more easily decoded in one's head by mentally using the table.
Read more about this topic: Tap Code
Famous quotes containing the word design:
“Teaching is the perpetual end and office of all things. Teaching, instruction is the main design that shines through the sky and earth.”
—Ralph Waldo Emerson (1803–1882)
“With wonderful art he grinds into paint for his picture all his moods and experiences, so that all his forces may be brought to the encounter. Apparently writing without a particular design or responsibility, setting down his soliloquies from time to time, taking advantage of all his humors, when at length the hour comes to declare himself, he puts down in plain English, without quotation marks, what he, Thomas Carlyle, is ready to defend in the face of the world.”
—Henry David Thoreau (1817–1862)
“For I choose that my remembrances of him should be pleasing, affecting, religious. I will love him as a glorified friend, after the free way of friendship, and not pay him a stiff sign of respect, as men do to those whom they fear. A passage read from his discourses, a moving provocation to works like his, any act or meeting which tends to awaken a pure thought, a flow of love, an original design of virtue, I call a worthy, a true commemoration.”
—Ralph Waldo Emerson (1803–1882)