Editing Morse code (section)

{{short description|Transmission of language with brief pulses}}
{{Other uses|Morse Code (disambiguation)}}
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[[File:International Morse Code.svg|thumb|upright=1.2|Chart of the Morse code 26&nbsp;letters and 10&nbsp;numerals<ref name=ITU-R-M-1677/>]]
{{anchor|MorseKey}}[[File:Morsetaste.jpg|thumb|right|This Morse key was originally used by [[Gotthard railway#The Gotthard railway telegraph network|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>]]

'''Morse code''' is a [[telecommunications]] method which [[Character encoding|encodes]] [[Written language|text]] characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''.<ref name=Beechey-1876/><ref name=Camm-1941/> Morse code is named after [[Samuel Morse]], one of the early developers of the system adopted for [[electrical telegraph]]y.

'''International Morse code''' encodes the 26&nbsp;[[ISO basic Latin alphabet|basic Latin letters]] '''{{sc|A}}''' to '''{{sc|Z}}''', one [[Diacritic|accented]] Latin letter ('''{{sc|É}}'''), the [[Arabic numerals]], and a small set of punctuation and procedural signals ([[Prosigns for Morse code|prosigns]]). There is no distinction between upper and lower case letters.<ref name=ITU-R-M-1677/> Each Morse code symbol is formed by a sequence of ''dits'' and ''dahs''. The ''dit'' duration can vary for signal clarity and operator skill, but for any one message, once the [[rhythm]] is established, a [[beat (music)|half-beat]] is the basic unit of time measurement in Morse code. The duration of a ''dah'' is three times the duration of a ''dit'' (although some telegraphers deliberately exaggerate the length of a ''dah'' for clearer signalling). 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 [[Delimiter|separated by]] a space of duration equal to three ''dits'', and words are separated by a space equal to seven ''dits''.<ref name=ITU-R-M-1677/><ref name=TR-Paris-1949>{{cite report |title=Telegraph Regulations |orig-year=1947 |year=1949 |series=ITU History |place=Geneva, CH |publisher=[[International Telecommunication Union]] |url=https://search.itu.int/history/HistoryDigitalCollectionDocLibrary/1.36.48.en.100.pdf |page=42 |quote=the space between two words is equal to seven dots;}} — Annexed to the ''International Telecommunication Convention'', Atlantic City, 1947; revised Paris, 1949.</ref>{{efn|
Until 1949, words were separated by a space equal to five ''dits''.<ref name=TR-Cairo-1938>{{cite report |title=Telegraph Regulations |orig-year=1932 |year=1938 |series=ITU History |place=Geneva, CH |publisher=[[International Telecommunication Union]] |url=https://search.itu.int/history/HistoryDigitalCollectionDocLibrary/1.35.48.en.100.pdf#search=morse%201938 |page=39 |quote=The space between two words is equal to five dots.}} — Annexed to the ''International Telecommunication Convention'', Madrid, 1932; revised Cairo, 1938.</ref>
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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.<ref name=Army-1968-TM-11-459/><ref name=Navy-1957-RM32-10228B/> 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.<ref name=Preece-Sivewright-1891/><ref name=Army-1939-FM-24-5/> The current or wave is present during the time period of the ''dit'' or ''dah'' and absent during the time between ''dits'' and ''dahs''.<ref name=Everitt-1937/><ref name=Radio-mag-Handbook-1940/>

Since many natural languages use more than the 26&nbsp;letters of the [[Latin alphabet]], [[Morse code for non-Latin alphabets|Morse alphabets]] have been developed for those languages, largely by transliteration of existing codes.<ref name=War-1943-TM-11-459/>

To increase the efficiency of transmission, Morse code was originally designed so that the duration of each symbol is approximately [[Entropy encoding|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 '''{{sc|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''.{{efn|The time needed to transmit the word '''{{sc|paris}}''' is typically used as the standard "word" for calculating the "word per minute" rate. Other standard "words" such as '''{{sc|codex}}''' are also used.<ref name=Army-1968-TM-11-459/>}}<ref name=Army-1968-TM-11-459/>