What (who) is Morse code - definition
![Baden-Powell's]] mnemonic chart from 1918](https://commons.wikimedia.org/wiki/Special:FilePath/Morse Code Mnemonic chart from Girl Guides handbook 1916.jpg?width=200 "Baden-Powell's]] mnemonic chart from 1918")
![prosigns]] are circled in red with red text; unofficial prosigns are orange.](https://commons.wikimedia.org/wiki/Special:FilePath/Morse code tree3.png?width=200 "prosigns]] are circled in red with red text; unofficial prosigns are orange.")
![ITU]] standard.](https://commons.wikimedia.org/wiki/Special:FilePath/Morse comparison.svg?width=200 "ITU]] standard.")
![Gotthard railway]], later by a [[shortwave radio]] amateur<ref>Gotthard morse key used by shortwave radio amateur [https://www.qrz.com/db/HB9BFM HB9BFM]. Retrieved 25 September 2021.</ref>](https://commons.wikimedia.org/wiki/Special:FilePath/Morsetaste.jpg?width=200 "Gotthard railway]], later by a [[shortwave radio]] amateur<ref>Gotthard morse key used by shortwave radio amateur [https://www.qrz.com/db/HB9BFM HB9BFM]. Retrieved 25 September 2021.</ref>")
![signalman]] sends Morse code signals in 2005.](https://commons.wikimedia.org/wiki/Special:FilePath/Seaman send Morse code signals.jpg?width=200 "signalman]] sends Morse code signals in 2005.")
.jpg?width=200 "Single needle telegraph instrument")
![sounder]]. The signal is "on" when the knob is pressed, and "off" when it is released. Length and timing of the ''dits'' and ''dahs'' are entirely controlled by the [[telegraphist]].](https://commons.wikimedia.org/wiki/Special:FilePath/Telegraph key and sounder, L.C.T. (L. C. Tillotson) and Co., 8 Dey Street, NY - Bennington Museum - Bennington, VT - DSC08636.JPG?width=200 "sounder]]. The signal is \"on\" when the knob is pressed, and \"off\" when it is released. Length and timing of the ''dits'' and ''dahs'' are entirely controlled by the [[telegraphist]].")
![A U.S. Navy Morse Code training class in 2015. The sailors will use their new skills to collect [[signals intelligence]].](https://commons.wikimedia.org/wiki/Special:FilePath/U.S. Navy 151103-N-XX082-001 Morse Code training 2015.jpg?width=200 "A U.S. Navy Morse Code training class in 2015. The sailors will use their new skills to collect [[signals intelligence]].")
![[[Vibroplex]] brand semiautomatic key (generically called a "bug"). The paddle, when pressed to the right by the thumb, generates a series of ''dits'', the length and timing of which are controlled by a sliding weight toward the rear of the unit. When pressed to the left by the knuckle of the index finger, the paddle generates a single ''dah'', the length of which is controlled by the operator. Multiple ''dahs'' require multiple presses. Left-handed operators use a key built as a mirror image of this one.](https://commons.wikimedia.org/wiki/Special:FilePath/VibroplexBug.jpg?width=200 "[[Vibroplex]] brand semiautomatic key (generically called a \"bug\"). The paddle, when pressed to the right by the thumb, generates a series of ''dits'', the length and timing of which are controlled by a sliding weight toward the rear of the unit. When pressed to the left by the knuckle of the index finger, the paddle generates a single ''dah'', the length of which is controlled by the operator. Multiple ''dahs'' require multiple presses. Left-handed operators use a key built as a mirror image of this one.")
Wikipedia
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. Morse code is named after Samuel Morse, one of the inventors of the telegraph.
International Morse code encodes the 26 basic Latin letters A through Z, one accented Latin letter (É), the Arabic numerals, and a small set of punctuation and procedural signals (prosigns). There is no distinction between upper and lower case letters. Each Morse code symbol is formed by a sequence of dits and dahs. The dit duration is the basic unit of time measurement in Morse code transmission. The duration of a dah is three times the duration of a dit. Each dit or dah within an encoded character is followed by a period of signal absence, called a space, equal to the dit duration. The letters of a word are separated by a space of duration equal to three dits, and words are separated by a space equal to seven dits.
Morse code can be memorized and sent in a form perceptible to the human senses, e.g. via sound waves or visible light, such that it can be directly interpreted by persons trained in the skill. Morse code is usually transmitted by on-off keying of an information-carrying medium such as electric current, radio waves, visible light, or sound waves. The current or wave is present during the time period of the dit or dah and absent during the time between dits and dahs.
Since many natural languages use more than the 26 letters of the Latin alphabet, Morse alphabets have been developed for those languages, largely by transliteration of existing codes.
To increase the efficiency of encoding, Morse code was originally designed so that the length of each symbol is approximately inverse to the frequency of occurrence of the character that it represents in text of the English language. Thus the most common letter in English, the letter E, has the shortest code – a single dit. Because the Morse code elements are specified by proportion rather than specific time durations, the code is usually transmitted at the highest rate that the receiver is capable of decoding. Morse code transmission rate (speed) is specified in groups per minute, commonly referred to as words per minute.
