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Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called dots and dashes, or dits and dahs. [3] [4] Morse code is named after Samuel Morse, one of the early developers of the system adopted for electrical telegraphy .
X. Y. Z. The tap code, sometimes called the knock code, is a way to encode text messages on a letter-by-letter basis in a very simple way. The message is transmitted using a series of tap sounds, hence its name. [1] The tap code has been commonly used by prisoners to communicate with each other. The method of communicating is usually by tapping ...
The arms were rotated by ropes, and later chains. The barred arm positions indicated numbers 1 to 6 clockwise from the bottom left and the unbarred arm 7,8,9, STOP and REPEAT. The vane positions indicate code numbers. A message was sent by sending numbers sequentially to make up a code. As with other systems the code was decoded via a code book.
SOS is a Morse code distress signal ( ), used internationally, originally established for maritime use. In formal notation SOS is written with an overscore line ( SOS ), to indicate that the Morse code equivalents for the individual letters of "SOS" are transmitted as an unbroken sequence of three dots / three dashes / three dots, with no ...
The pigpen cipher (alternatively referred to as the masonic cipher, Freemason's cipher, Rosicrucian cipher, Napoleon cipher, and tic-tac-toe cipher) [2] [3] is a geometric simple substitution cipher, which exchanges letters for symbols which are fragments of a grid. The example key shows one way the letters can be assigned to the grid.
In telephony, beep lines [a] were improvised conference calls hosted over busy signals, loop-around test tones, or certain automated informational service numbers, active in the United States from the mid-1950s to the mid-1980s. [5] [6] [7] [1] [3] These lines allowed callers to communicate with up to dozens of other people simultaneously, the ...
Patricia Davies (née Owtram; born 19 June 1923) is an English former codebreaker who served as a special duties linguist in the Women’s Royal Naval Service during World War II. She and her younger sister Jean Argles are often referred to as "The Codebreaking Sisters". [1] As a teenage interceptor, Davies listened to radio transmissions in ...
Caesar cipher. The action of a Caesar cipher is to replace each plaintext letter with a different one a fixed number of places down the alphabet. The cipher illustrated here uses a left shift of 3, so that (for example) each occurrence of E in the plaintext becomes B in the ciphertext. In cryptography, a Caesar cipher, also known as Caesar's ...