View source for Morse code

{{short description|Transmission of language with brief pulses}}
{{Other uses|Morse Code (disambiguation)}}
{{pp-vandalism|small=yes}}
{{pp-move-indef}}
{{use dmy dates|date=May 2021}}
[[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 established it 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>
}}

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/>

==Development and history==
===Pre-Morse telegraphs and codes===
[[File:Single needle telegraph (Rankin Kennedy, Electrical Installations, Vol V, 1903).jpg|thumb|200px|left|Single needle telegraph instrument]]
Early in the nineteenth century, European experimenters made progress with electrical signaling systems, using a variety of techniques including [[static electricity]] and electricity from [[Voltaic pile]]s producing [[Electrochemistry|electrochemical]] and [[electromagnetism|electromagnetic]] changes. These experimental designs were precursors to practical telegraphic applications.<ref name=Fahie-1884/>
[[File:Telegraph key and sounder, L.C.T. (L. C. Tillotson) and Co., 8 Dey Street, NY - Bennington Museum - Bennington, VT - DSC08636.JPG|thumb|250px|right|[[Telegraph key]] and [[Telegraph sounder|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]]]]
Following the discovery of [[electromagnetism]] by [[Hans Christian Ørsted]] in 1820 and the invention of the [[electromagnet]] by [[William Sturgeon]] in 1824, there were developments in [[Electrical telegraph|electromagnetic telegraphy]] in Europe and America. Pulses of [[electric current]] were sent along wires to control an electromagnet in the receiving instrument. Many of the earliest telegraph systems used a single-needle system which gave a very simple and robust instrument. However, it was slow, as the receiving operator had to alternate between looking at the needle and writing down the message. In Morse code, a deflection of the needle to the left corresponded to a ''dit'' and a deflection to the right to a ''dah''.<ref name=UK-Engr-1919-1938/> The needle clicked each time it moved to the right or left. By making the two clicks sound different (by installing one ivory and one metal stop), transmissions on the single needle device became audible as well as visible, which led in turn to the ''Double Plate [[Telegraph sounder|Sounder]]'' System.<ref name=Freebody-1959/>

[[William Fothergill Cooke|William Cooke]] and [[Charles Wheatstone]] in [[United Kingdom|Britain]] developed an electrical telegraph that used electromagnets in its receivers. They obtained an English patent in June&nbsp;1837 and demonstrated it on the London and Birmingham Railway, making it the first commercial telegraph. [[Carl Friedrich Gauss]] and [[Wilhelm Eduard Weber]] (1833) as well as [[Carl August von Steinheil]] (1837) used codes with varying word lengths for their telegraph systems.<ref name=Smithsonian-Report-1879/> In 1841, Cooke and Wheatstone built a telegraph that printed the letters from a wheel of typefaces struck by a hammer.<ref name=Burns-2004/>{{rp|page=79}}

{{clear left}}

===Samuel Morse and Alfred Vail===
[[File:Morse Code Receiver.jpg|thumb|Morse code receiver that records on paper tape]]
The American artist [[Samuel F. B. Morse|Samuel Morse]], the American [[physicist]] [[Joseph Henry]], and mechanical engineer [[Alfred Vail]] developed an [[electrical telegraph]] system. The simple "on or off" nature of its signals made it desirable to find a method of transmitting natural language using only electrical pulses and the silence between them. Around 1837, Morse therefore developed such a method, an early forerunner to the modern International Morse code.<ref name=Burns-2004/>{{rp|page=79}}

The Morse system for [[telegraphy]], which was first used in about 1844, was designed to make indentations on a paper tape when electric currents were received. Morse's original telegraph receiver used a mechanical clockwork to move a paper tape. When an electrical current was received, an electromagnet engaged an armature that pushed a stylus onto the moving paper tape, making an indentation on the tape. When the current was interrupted, a spring retracted the stylus and that portion of the moving tape remained unmarked. Morse code was developed so that operators could translate the indentations marked on the paper tape into text messages.

In his earliest design for a code, Morse had planned to transmit only numerals, and to use a codebook to look up each word according to the number which had been sent. However, the code was soon expanded by [[Alfred Vail]] in 1840 to include letters and special characters, so it could be used more generally. Vail estimated the frequency of use of letters in the [[English language]] by counting the movable type he found in the type-cases of a local newspaper in [[Morristown, New Jersey]].<ref name=Burns-2004/>{{rp|page=84}} The shorter marks were called "dots" and the longer ones "dashes", and the letters most commonly used were assigned the shortest sequences of dots and dashes. This code, first used in 1844, was what later became known as ''Morse landline code'', ''[[American Morse code]]'', or ''Railroad Morse'', until the end of railroad telegraphy in the U.S. in the 1970s.{{citation needed|date=May 2021}}

===Operator-led change from graphical to audible code===
In the original Morse telegraph system, the receiver's armature made a clicking noise as it moved in and out of position to mark the paper tape. Early telegraph operators soon learned that they could translate the clicks directly into dots and dashes, and write these down by hand, thus making the paper tape unnecessary. When Morse code was adapted to [[radio communication]], the dots and dashes were sent as short and long tone pulses.

Later telegraphy training found that people become more proficient at receiving Morse code when it is taught "like a language", with each code perceived as a whole "word" instead of a sequence of separate dots and dashes, such as might be shown on a page.<ref name=ARRL-Learning-Morse/>

With the advent of tones produced by radiotelegraph receivers, the operators began to vocalize a dot as ''dit'', and a dash as ''dah'', to reflect the sounds of Morse code they heard. To conform to normal sending speed, ''dits'' which are not the last element of a code became voiced as ''di''. For example, the {{nobr|letter '''{{sc|L}}'''}} ({{morse|dot|dash|dot|dot}}) is voiced as {{nowrap| ''di dah di dit''}}.<ref name=Carron-1986/><ref name=Eckersley-1985/> Morse code was sometimes facetiously known as "iddy-umpty", a ''dit'' lampooned as "iddy" and a ''dah'' as "umpty", leading to the word "[[umpteen]]".<ref name=OED-iddy-umpty/>
[[File:Morse comparison.svg|thumb|350px|{{anchor|American Morse anchor}}Comparison of historical versions of Morse code with the current standard. ''Left'':&nbsp;Later [[American Morse code]] from 1844.<ref name=Smithsonian-Report-1879/> ''Center'':&nbsp;The modified and rationalized version used by [[Friedrich Clemens Gerke|Friedrich Gerke]] on German railways. ''Right'':&nbsp;Current [[International Telecommunication Union|ITU]] standard.]]

===Gerke's refinement of Morse's code <span class="anchor" id="Gerke code"></span>===
{{anchor|Hamburg}}The Morse code, as specified in the current international standard, ''International Morse Code Recommendation'', [[ITU-R]]&nbsp;M.1677-1,<ref name=ITU-R-M-1677/> was derived from a much-improved proposal by [[Friedrich Clemens Gerke|Friedrich Gerke]] in 1848 that became known as the "Hamburg alphabet", its only real defect being the use of an excessively long code ({{morse|dot|dash|dot|dot|dot}} and later the equal duration code {{morse|dash|dash|dash}}) for the frequently used vowel '''{{sc|O}}'''.

Gerke changed many of the codepoints, in the process doing away with the different length dashes and different inter-element spaces of [[American Morse code|American Morse]], leaving only two coding elements, the dot and the dash. Codes for [[German language|German]] [[Umlaut (linguistics)|umlaut]]ed vowels and '''{{sc|CH}}''' were introduced. Gerke's code was adopted in Germany and Austria in 1851.<ref name=Deutsch-Österreich-Telegr-1851/>

This finally led to the International Morse code in 1865. The International Morse code adopted most of Gerke's codepoints. The codes for '''{{sc|O}}''' and '''{{sc|P}}''' were taken from a code system developed by Steinheil. A new codepoint was added for '''{{sc|J}}''' since Gerke did not distinguish between '''{{sc|I}}''' and '''{{sc|J}}'''. Changes were also made to '''{{sc|X}}''', '''{{sc|Y}}''', and '''{{sc|Z}}'''. This left only four codepoints identical to the original Morse code, namely '''{{sc|E}}''', '''{{sc|H}}''', '''{{sc|K}}''' and '''{{sc|N}}''', and the latter two had their ''dahs'' extended to full length. The original American code being compared dates to 1838; the later American code shown in the table was developed in 1844.<ref name=Smithsonian-Report-1879/>

===Radiotelegraphy and aviation===
In the 1890s, Morse code began to be used extensively for early [[radio]] communication before it was possible to transmit voice. In the late 19th and early 20th&nbsp;centuries, most high-speed international communication used Morse code on telegraph lines, undersea cables, and radio circuits.

Although previous transmitters were bulky and the [[Spark-gap transmitter|spark gap system of transmission]] was dangerous and difficult to use, there had been some early attempts: In 1910, the U.S. Navy experimented with sending Morse from an airplane.<ref name=Howeth-1963/> However the first regular aviation radiotelegraphy was on [[airship]]s, which had space to accommodate the large, heavy radio equipment then in use. The same year, 1910, a radio on the airship [[America (airship)|''America'']] was instrumental in coordinating the rescue of its crew.<ref name=K2TQN-blog/>

During [[World War I|World War&nbsp;I]], [[Zeppelin|Zeppelin airships]] equipped with radio were used for bombing and naval scouting,<ref name=Pop-Sci-1918-04-Zeppelin/> and ground-based radio direction finders were used for airship navigation.<ref name=Pop-Sci-1918-04-Zeppelin/> Allied airships and military aircraft also made some use of radiotelegraphy.

However, there was little aeronautical radio in general use during [[World War I]], and in the 1920s, there was no radio system used by such important flights as that of [[Charles Lindbergh]] from [[New York City|New York]] to [[Paris]] in 1927. Once he and the ''[[Spirit of St. Louis]]'' were off the ground, Lindbergh was truly incommunicado and alone. Morse code in aviation began regular use in the mid-1920s. By 1928, when the first airplane flight was made by the [[Southern Cross (aircraft)|''Southern Cross'']] from California to Australia, one of its four crewmen was a radio operator who communicated with ground stations via [[wireless telegraphy|radio telegraph]].

Beginning in the 1930s, both civilian and military pilots were required to be able to use Morse code, both for use with early communications systems and for identification of navigational beacons that transmitted continuous two- or three-letter identifiers in Morse code. [[Aeronautical chart]]s show the identifier of each navigational aid next to its location on the map.

In addition, rapidly moving field armies could not have fought effectively without radiotelegraphy; they moved more quickly than their communications services could put up new telegraph and telephone lines. This was seen especially in the [[blitzkrieg]] offensives of the [[Nazi German]] [[Wehrmacht]] in [[Poland]], [[Belgium]], [[France]] (in 1940), the [[Soviet Union]], and in [[North Africa]]; by the [[British Army]] in [[North Africa]], [[Italy]], and the [[Netherlands]]; and by the [[U.S. Army]] in France and Belgium (in 1944), and in southern Germany in 1945.

=== Maritime flash telegraphy and radio telegraphy ===
[[File:U.S. Navy 151103-N-XX082-001 Morse Code training 2015.jpg|thumb|A U.S. Navy Morse Code training class in 2015. The sailors will use their new skills to collect [[signals intelligence]].]]
Radiotelegraphy using Morse code was vital during [[World War II]], especially in carrying messages between the [[warship]]s and the [[naval base]]s of the belligerents. Long-range ship-to-ship communication was by radio telegraphy, using [[encrypted]] messages because the voice radio systems on ships then were quite limited in both their range and their security. Radiotelegraphy was also extensively used by [[warplane]]s, especially by long-range [[scout plane|patrol planes]] that were sent out by navies to scout for enemy warships, cargo ships, and troop ships.

Morse code was used as an international standard for maritime distress until 1999 when it was replaced by the [[Global Maritime Distress and Safety System]]. When the [[French Navy]] ceased using Morse code on January 31, 1997, the final message transmitted was ''"Calling all. This is our last call before our eternal silence."''<ref name=Economist-1999-01-23/>

===Demise of commercial telegraphy===
In the United States the final commercial Morse code transmission was on July 12, 1999, signing off with Samuel Morse's original 1844 message, [[wikt:what hath God wrought|'''{{sc|What hath God wrought}}''']], and the [[prosign]] {{sc|'''{{overline|SK}}'''}} ("end of contact").<ref name=Maritime-Radio-Hist-Soc-pab1_7/>

{{as of|2015}}, the [[United States Air Force]] still trains ten people a year in Morse.<ref name=Swling-2015-12-10/>

The [[United States Coast Guard]] has ceased all use of Morse code on the radio, and no longer monitors any [[radio frequencies]] for Morse code transmissions, including the international [[medium frequency]] (MF) distress frequency of {{nobr|[[500 kHz]].<ref name=USCG-2011-Circ-1367-Amd/>}} However, the [[Federal Communications Commission]] still grants commercial radiotelegraph operator licenses to applicants who pass its code and written tests.<ref name=FCC-radiotelegraph/> Licensees have reactivated the old California coastal Morse station [[KPH (radio)|KPH]] and regularly transmit from the site under either this [[call sign]] or as KSM. Similarly, a few U.S. [[museum ship]] stations are operated by Morse enthusiasts.<ref name=Maritime-Radio-Hist-Soc-main/>

== Operator proficiency ==
[[File:Bencher paddle.jpg|thumb|A commercially manufactured iambic paddle used in conjunction with an electronic keyer to generate high-speed Morse code, the timing of which is controlled by the electronic keyer.{{efn|
These modern "iambic" keys are operated by one or two "paddles" pressed left and right, instead of pressing down a lever, as in the traditional telegraph keys, pictured at the start of this article. Operating paddle keys is similar to using the old [[Vibroplex]] clockwork telegraph keys: Pressing the paddle to the right generates a series of repeated ''dits'' until the paddle is released; pressing the paddle to the left produces a similar series of ''dahs''; and with two-paddle electronic keys, squeezing the two paddles from both sides produces an alternating {{nowrap| ''dit dah dit dah'' }} sequence.
:
For left-handed operators, the actions of the two paddles are often reversed.
}} ]]

Morse code speed is measured in [[words per minute]] ({{sc|wpm}}) or characters per minute ({{sc|cpm}}). Characters have differing lengths because they contain differing numbers of ''dits'' and ''dahs''. Consequently, words also have different lengths in terms of dot duration, even when they contain the same number of characters. For this reason, some standard word is adopted for measuring operators' transmission speeds: Two such standard words in common use are '''{{sc|PARIS}}''' and '''{{sc|CODEX}}'''.<ref name=Perera-W1TP-Teleg-Mus/> Operators skilled in Morse code can often understand ("copy") code in their heads at rates in excess of 40&nbsp;{{sc|wpm}}.

In addition to knowing, understanding, and being able to copy the standard written alpha-numeric and punctuation characters or symbols at high speeds, skilled high-speed operators must also be fully knowledgeable of all of the special unwritten Morse code symbols for the standard [[Prosigns for Morse code]] and the meanings of these special procedural signals in standard Morse code [[communications protocol]].

International contests in code copying are still occasionally held. In July&nbsp;1939 at a contest in [[Asheville, North Carolina]] in the United States, Theodore Roosevelt McElroy ('''{{sc|W1JYN}}''') set a still-standing record for Morse copying, 75.2&nbsp;{{sc|wpm}}.<ref name=Pierpont-N0HFF-2004/> Pierpont (2004) also notes that some operators may have passed 100&nbsp;{{sc|wpm}}.<ref name=Pierpont-N0HFF-2004/> By this time, they are "hearing" phrases and sentences rather than words. The fastest speed ever sent by a straight key was achieved in 1942 by Harry Turner ([[call sign|'''{{sc|W9YZE}}''']]) (d. 1992) who reached 35&nbsp;{{sc|wpm}} in a demonstration at a U.S. Army base. To accurately compare code copying speed records of different eras it is useful to keep in mind that different standard words (50&nbsp;dit durations versus 60&nbsp;dit durations) and different interword gaps (5&nbsp;dit durations versus 7&nbsp;dit durations) may have been used when determining such speed records. For example, speeds run with the '''{{sc|CODEX}}''' standard word and the '''{{sc|PARIS}}''' standard may differ by up to 20%.

Today among amateur operators there are several organizations that recognize high-speed code ability, one group consisting of those who can copy Morse at 60&nbsp;{{sc|wpm}}.<ref name=Morsecode-NL-EHSC/> Also, Certificates of Code Proficiency are issued by several amateur radio societies, including the [[American Radio Relay League]]. Their basic award starts at 10&nbsp;{{sc|wpm}} with endorsements as high as 40&nbsp;{{sc|wpm}}, and are available to anyone who can copy the transmitted text. Members of the [[Boy Scouts of America]] may put a Morse interpreter's strip on their uniforms if they meet the standards for translating code at 5&nbsp;{{sc|wpm}}.

[[File:Seaman send Morse code signals.jpg|thumb|left|upright|A U.S. Navy [[Signalman (rank)|signalman]] sends Morse code signals in 2005.]]

Through May&nbsp;2013, the First, Second, and Third Class (commercial) Radiotelegraph Licenses using code tests based upon the '''{{sc|CODEX}}''' standard word were still being issued in the United States by the Federal Communications Commission. The First Class license required 20&nbsp;{{sc|wpm}} code group and 25&nbsp;{{sc|wpm}} text code proficiency, the others 16&nbsp;{{sc|wpm}} code group test (five letter blocks sent as simulation of receiving encrypted text) and 20&nbsp;{{sc|wpm}} code text (plain language) test. It was also necessary to pass written tests on operating practice and electronics theory. A unique additional demand for the First Class was a requirement of a year of experience for operators of shipboard and coast stations using Morse. This allowed the holder to be chief operator on board a passenger ship. However, since 1999 the use of satellite and very high-frequency maritime communications systems ([[GMDSS]]) has made them obsolete. (By that point meeting experience requirement for the First was very difficult.)

Currently, only one class of license, the Radiotelegraph Operator License, is issued. This is granted either when the tests are passed or as the Second and First are renewed and become this lifetime license. For new applicants, it requires passing a written examination on electronic theory and radiotelegraphy practices, as well as 16&nbsp;{{sc|wpm}} code-group and 20&nbsp;{{sc|wpm}} text tests. However, the code exams are currently waived for holders of Amateur Extra Class licenses who obtained their operating privileges under the old 20&nbsp;{{sc|wpm}} test requirement.

== International Morse code ==
Morse codes of one version or another have been in use for more than 160&nbsp;years — longer than any other [[electrical]] message encoding system. What is called Morse code today is actually somewhat different from what was originally developed by Vail and Morse. The Modern International Morse code, or ''continental code'', was created by [[Friedrich Clemens Gerke]] in 1848 and initially used for telegraphy between [[Hamburg]] and [[Cuxhaven]] in Germany. Gerke changed nearly half of the alphabet and all of the [[Numerical digit|numerals]], providing the foundation for the modern form of the code. After some minor changes to the letters and a complete revision of the numerals, International Morse Code was standardized by the International Telegraphy Congress in 1865 in Paris, and later became the standard adopted by the [[International Telecommunication Union]] (ITU). Morse and Vail's final code specification, however, was only really used only for land-line telegraphy in the United States and Canada, with the International code used everywhere else, including all ships at sea and sailing in North American waters. Morse's version became known as ''[[American Morse code]]'' or ''railroad code'', and is now almost never used, with the possible exception of historical re-enactments.

===Aviation===
[[File:VFR Chart Cayo Largo Del Sur VOR-DME.png|thumb|Cayo Largo Del Sur VOR-DME]]
In [[aviation]], pilots use [[radio navigation]] aids. To allow pilots to ensure that the stations they intend to use are serviceable, the stations transmit a set of identification letters (usually a two-to-five-letter version of the station name) in Morse code. Station identification letters are shown on air navigation charts. For example, the [[VHF omnidirectional range|VOR-DME]] based at [[Vilo Acuña Airport]] in [[Cayo Largo del Sur|Cayo Largo del Sur, Cuba]] is identified by "[[call sign|UCL]]", and Morse code '''{{sc|UCL}}''' is repeatedly transmitted on its radio frequency. 

In some countries, during periods of maintenance, the facility may instead transmit the signal {{nobr|'''{{sc|TEST}}'''}} ({{nobr|{{Morse|dash}} {{Morse|dot}}{{Morse|dot|dot|dot}}{{Morse|dash}}}}), or the [[call sign|identification]] may be removed, which tells [[Aviator|pilots]] and [[navigator]]s that the station is unreliable. In Canada, the identification is removed entirely to signify the navigation aid is not to be used.<ref name=FAA-2015-Air-Nav/><ref name=Canada-AIM-2003-COM-3-2/>

In the aviation service, Morse is typically sent at a very slow speed of about 5&nbsp;words per minute. In the U.S., pilots do not actually have to know Morse to identify the transmitter because the dot/dash sequence is written out next to the transmitter's symbol on aeronautical charts. Some modern navigation receivers automatically translate the code into displayed letters.[[File:NonDirectional Beacon WG.ogg|thumb|right|The sound of non-directional beacon '''{{sc|WG}}''', on 248&nbsp;kHz, located at 49.8992&nbsp;North, 97.349197&nbsp;West,<ref name=Pilotnav-sps-10404/> near [[Winnipeg James Armstrong Richardson International Airport|Winnipeg's main airport]]]]

===Amateur radio===
[[File:VibroplexBug.jpg|thumb|right|[[Vibroplex]] brand semiautomatic key{{efn|name=bug_op_note}} (informally called a "bug" since it vaguely resembles a [[stick insect]]). ]]
International Morse code today is most popular among [[amateur radio]] operators, in the mode commonly referred to as "[[continuous wave]]" or "CW".{{efn|
The name ''[[continuous wave]]'' was chosen to distinguish the single-frequency [[List of amateur radio modes|transmission mode]] from the sliding-frequency [[damped wave (radio transmission)|damped wave signals]] from now-banned [[spark-gap transmitter]]s. Although the modern {{sc|on}} / {{sc|off}} signal itself is interrupted, not continuous, it does (ideally) maintain a single, constant frequency [[carrier wave]] throughout any one transmission.
}}
Other, faster keying methods are available in radio telegraphy, such as [[frequency-shift keying]] (FSK).

The original amateur radio operators used Morse code exclusively since voice-capable radio transmitters did not become commonly available until around 1920. Until 2003, the [[International Telecommunication Union]] mandated Morse code proficiency as part of the amateur radio licensing procedure worldwide. However, the [[World Radiocommunication Conference]] of 2003 made the Morse code requirement for amateur radio licensing optional.<ref name=IARU-2003-07-03/> Many countries subsequently removed the Morse requirement from their license requirements.<ref name=ARRL-Letter-2005-08-12/>
[[File:2022-11-06 0204 40 Meter CW.ogg|thumb|Morse code recorded on the [[40-meter band|40&nbsp;meter ham radio band]] (31&nbsp;sec).]]
Until 1991, a demonstration of the ability to send and receive Morse code at a minimum of five words per minute ({{sc|wpm}}) was required to receive an amateur radio license for use in the United States from the [[Federal Communications Commission]]. Demonstration of this ability was still required for the privilege to use the [[shortwave|shortwave bands]]. Until 2000, proficiency at the 20&nbsp;{{sc|wpm}} level was required to receive the highest level of amateur license (Amateur Extra Class); effective April 15, 2000, in the FCC reduced the Extra Class requirement to 5&nbsp;{{sc|wpm}}.<ref name=ARRL-2000-Part-97-amended/> Finally, effective on February 23, 2007, the FCC eliminated the Morse code proficiency requirements from all amateur radio licenses.

While voice and data transmissions are limited to specific amateur radio bands under U.S. rules, Morse code is permitted on all amateur bands: [[2200-meter band|LF]], [[630-meter band|MF low]], [[160-meter band|MF high]], [[High frequency|HF]], [[VHF]], and [[UHF]]. In some countries, certain portions of the amateur radio bands are reserved for transmission of Morse code signals only.

Because Morse code transmissions employ an [[on-off keying|on-off keyed]] radio signal, it requires less complex equipment than other [[List of amateur radio modes|radio transmission modes]]. Morse code also uses less [[signal bandwidth|bandwidth]] (typically only 100–150&nbsp;[[hertz|Hz]] wide, although only for a slow data rate) than voice communication (roughly 2,400~2,800&nbsp;Hz used by [[single-sideband modulation|SSB voice]]).

Morse code is usually received as a high-pitched audio tone, so transmissions are easier to copy than voice through the noise on congested frequencies, and it can be used in very high noise / low signal environments. The fact that the transmitted power is concentrated into a very limited bandwidth makes it possible to use narrow receiver filters, which suppress or eliminate interference on nearby frequencies. The narrow signal bandwidth also takes advantage of the natural aural selectivity of the human brain, further enhancing weak signal readability.{{citation needed|date=December 2020}} This efficiency makes CW extremely useful for [[DXing|DX (long distance) transmissions]], as well as for low-power transmissions (commonly called "[[QRP operation]]", from the [[Q-code]] for "reduce power"). There are several amateur clubs that require solid high speed copy, the highest of these has a standard of 60&nbsp;{{sc|WPM}}. The [[American Radio Relay League]] offers a code proficiency certification program that starts at 10&nbsp;{{sc|wpm}}.

The relatively limited speed at which Morse code can be sent led to the development of an extensive number of abbreviations to speed communication. These include prosigns, [[Q code]]s, and a set of [[Morse code abbreviations]] for typical message components. For example, '''{{sc|CQ}}''' is broadcast to be interpreted as "seek you" (I'd like to converse with anyone who can hear my signal). The abbreviations '''{{sc|OM}}''' (old man), '''{{sc|YL}}''' (young lady), and '''{{sc|XYL}}''' ("ex-young lady" – wife) are common. '''{{sc|YL}}''' or '''{{sc|OM}}''' is used by an operator when referring to the other operator (regardless of their actual age), and '''{{sc|XYL}}''' or '''{{sc|OM}}''' (rather than the expected '''{{sc|XYM}}''') is used by an operator when referring to his or her spouse. '''{{sc|QTH}}''' is "transmitting location" (spoken "my Q.T.H." is "my location"). The use of abbreviations for common terms permits conversation even when the operators speak different languages.

Although the traditional [[telegraph key]] (straight key) is still used by some amateurs, the use of mechanical semi-automatic [[keyer]]s{{efn|
name=bug_op_note|
The semiautomatic key paddle, when pressed to the right by the thumb, kicks a clockwork-like horizontal pendulum that generates a series of ''dits'', the length and timing of which are controlled by a sliding the pendulum 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 may use a key built as a mirror image of this one.
}} 
(informally called "bugs"), and of fully automatic electronic [[keyer]]s (called "single paddle" and either "double-paddle" or "iambic" keys) is prevalent today. [[Software]] is also frequently employed to produce and decode Morse code radio signals. The [[ARRL]] has a readability standard for robot encoders called ''ARRL Farnsworth spacing''<ref name=ARRL-x9004008-Farnsw/> that is supposed to have higher readability for both robot and human decoders. Some programs like WinMorse<ref name=Winmorse-custom-Farnsw/> have implemented the standard.

===Other uses===
Radio navigation aids such as [[VHF omnidirectional range|VOR]]s and [[Non-directional beacon|NDB]]s for aeronautical use broadcast identifying information in the form of Morse Code, though many [[VHF omnidirectional range|VOR]] stations now also provide voice identification.<ref name=FCC-AIM-ch-1/> Warships, including those of the [[U.S. Navy]], have long used [[signal lamp]]s to exchange messages in Morse code. Modern use continues, in part, as a way to communicate while maintaining [[radio silence]].

[[Automatic Transmitter Identification System (television)|Automatic Transmitter Identification System]] (ATIS) uses Morse code to identify uplink sources of analog satellite transmissions.
{{clear}}

Many [[amateur radio repeater]]s identify with Morse, even though they are used for voice communications.

===Applications for the general public===
[[File:SOS.svg|thumb|left|250px|Representation of Morse code '''{{overline|SOS}}''']]
An important application is signalling for help through [[SOS]], "{{morse|dot|dot|dot|dash|dash|dash|dot|dot|dot}}". This can be sent many ways: keying a radio on and off, flashing a mirror, toggling a flashlight, and similar methods. The [[SOS]] signal is not sent as three separate characters; rather, it is a [[prosigns for Morse code|prosign]] {{sc|'''{{overline|SOS}}'''}}, and is keyed without gaps between characters.<ref name=QSL-Prosigns/>

===Morse code as an assistive technology===
Morse code has been employed as an [[assistive technology]], helping people with a variety of [[disability|disabilities]] to communicate.<ref>{{cite book |first=Thomas W. |last=King |title=Modern Morse code in rehabilitation and education: New applications in assistive technology |publisher=Allyn & Bacon |date=2000 |isbn=9780205287512 |oclc=41070880 |url=https://archive.org/details/modernmorsecodei0000king/page/n8/mode/2up}}</ref><ref>{{cite web |first=Jim |last=Lubin |title=Morse Codes for Computer Access |date=2020 |publisher= |url=https://www.makoa.org/jlubin/morsecode.htm}}</ref>{{efn|
For people with severe disabilities, both one- and two-switch Morse can be difficult because both depend, to some extent, on timing. ... access products can also offer "three-switch Morse.". In three-switch Morse code, one switch signals dit, while another signals dah, just like two-switch Morse. But a third switch is used to indicate that the letter is complete. This removes the necessity of timing to send Morse code. – D.K. Anson (2018)<ref name=Anson-2018/>
}}<ref>{{cite web |title=Morse Code |date=2020 |publisher=Ace Centre (UK ACC Charity) |url=https://acecentre.org.uk/projects/morse-code}}</ref> For example, the Android operating system versions&nbsp;5.0 and higher allow users to input text using Morse Code as an alternative to a keypad or [[handwriting recognition]].<ref name=Google-android-9011881/>

Morse can be sent by persons with severe motion disabilities, as long as they have some minimal motor control. An original solution to the problem that caretakers have to learn to decode has been an electronic typewriter with the codes written on the keys. Codes were sung by users; see the voice typewriter employing Morse or votem.<ref name=Newell-Nabarro-1968/>

Morse code can also be translated by computer and used in a speaking communication aid. In some cases, this means alternately blowing into and sucking on a plastic tube ("[[sip-and-puff]]" interface). An important advantage of Morse code over [[Switch access scanning|row column scanning]] is that once learned, it does not require looking at a display. Also, it appears faster than scanning.

In one case reported in the radio amateur magazine ''[[QST]]'',<ref name=Ross-1992-03/> an old shipboard radio operator who had a [[stroke]] and lost the ability to speak or write could communicate with his physician (a radio amateur) by blinking his eyes in Morse. Two examples of communication in intensive care units were also published in ''[[QST magazine]]''.<ref name=Curt-1990-07/><ref name=Burch-1990-07/> Another example occurred in 1966 when [[prisoner of war]] [[Jeremiah Denton]], brought on television by his [[North Vietnam]]ese captors, Morse-blinked the word '''{{sc|TORTURE}}'''. In these two cases, interpreters were available to understand those series of eye-blinks.

==Representation, timing, and speeds==
{{Listen|filename=Wikipedia-Morse.ogg|title=A sample Morse code transmission|description=The text "Welcome to Wikipedia, the free encyclopedia that anyone can edit." sent as Morse code at 13&nbsp;{{sc|wpm}}.|format=[[Ogg]]}}

{{Listen |filename=A through Z in Morse code.ogg |title=Morse code '''{{sc|A}}'''–'''{{sc|Z}}''' |description='''{{sc|A B C D E F G H I J K L M N O P Q R S T U V W X Y Z}}''' in Morse code at 8&nbsp;{{sc|wpm}}. |format=[[Ogg]]}}
{{Inline audio|section}}
'''International Morse code is composed of five elements:'''<ref name=ITU-R-M-1677/>{{rp|at=§3}}

# short mark, dot or ''dit'' ({{morse|dot}}): "dit duration" is one time unit long
# long mark, dash or ''dah'' ({{morse|dash}}): three time units long
# inter-element gap between the ''dits'' and ''dahs'' within a character: one dot duration or one unit long
# short gap (between letters): three time units long
# medium gap (between words): seven time units long (formerly five<ref name=TR-Cairo-1938/>)

===Transmission===
Morse code can be transmitted in a number of ways: Originally as electrical pulses along a [[telegraph]] wire, but later extended to an audio tone, a radio signal with short and long tones, or high and low tones, or as a mechanical, audible, or visual signal (e.g. a flashing light) using devices like an [[Aldis lamp]] or a [[heliograph]], a common flashlight, or even a car horn. Some mine rescues have used pulling on a rope - a short pull for a dot and a long pull for a ''dah''. Ground forces send messages to aircraft with panel signalling, where a horizontal panel is a dah and a vertical panel a dit.<ref>[https://www.nato.int/nato_static_fl2014/assets/pdf/pdf_2018_01/20180111_nato-alphabet-sign-signal.pdf NATO phonetic alphabet, codes & signals.] Poster, 2018.</ref>

Morse messages are generally transmitted by a hand-operated device such as a [[telegraph key]], so there are variations introduced by the skill of the sender and receiver — more experienced operators can send and receive at faster speeds. In addition, individual operators differ slightly, for example, using slightly longer or shorter ''dahs'' or gaps, perhaps only for particular characters. This is called their "fist", and experienced operators can recognize specific individuals by it alone. A good operator who sends clearly and is easy to copy is said to have a "good fist". A "poor fist" is a characteristic of sloppy or hard to copy Morse code.

==== Digital storage ====
Morse code is transmitted using just two states (on and off). Morse code may be represented as a binary code, and that is what telegraph operators do when transmitting messages. Working from the above ITU definition and further defining a [[bit]] as a dot time, a Morse code sequence may be crudely represented a combination of the following five bit-strings:

# short mark, dot or ''dit'' ({{morse|dot}}): '1'b
# longer mark, dash or ''dah'' ({{morse|dash}}): '111'b
# intra-character gap (between the ''dits'' and ''dahs'' within a character): 0
# short gap (between letters): '000'b
# medium gap (between words): '0000000'b

The marks and gaps alternate: ''Dits'' and ''dahs'' are always separated by one of the gaps, and that the gaps are always separated by a ''dit'' or a ''dah''.

A more efficient binary encoding uses only two-bits for each ''dit'' or ''dah'' element, with the 1&nbsp;''dit''-length pause that must follow after each automatically included for every 2&nbsp;bit code. One possible coding is by number value for the length of signal tone sent one could use '01'b for a ''dit'' and the automatic single-dit pause after it, and '11'b for a ''dah'' and the automatic single-''dit'' following pause, and '00'b for the ''extra'' pause between letters (in effect, an end-of-letter mark). That leaves the code '10'b available for some other purpose, such as an escape character, or to more compactly represent the ''extra'' space between words (an end-of-word mark) instead of '00 00 00'b (only 6&nbsp;''dit'' lengths, since the 7th is automatically inserted as part of the prior ''dit'' or ''dah''). Although the ''dit'' and inter-letter pauses work out to be the same, for any letter containing a ''dah'', the two-bit encoding uses digital memory more compactly than the direct-conversion bit strings mentioned above. Including the letter-separating spaces, all International Morse letter codes pack into 12&nbsp;bits or less (5&nbsp;symbols), and most fit into 10&nbsp;bits or less (4&nbsp;symbols); most of the [[prosigns for Morse code|procedural signs]] fit into 14&nbsp;bits, with a few only needing 12&nbsp;bits (5&nbsp;symbols); and all digits require exactly 12&nbsp;bits.

For example, Morse '''{{sc|g}}''' ({{morse|dash|dash|dot}} + 2&nbsp;''extra'' empty dits for "end of letter") would binary-encode as '11'b, '11'b, '01'b, '00'b; when packed it is '1111 0100'b = 'F4'x, which stores into only one [[byte]] (two [[nibble]]s) (as does every three-element code). The bit encoding for the longer method mentioned earlier the same letter would encode as '1110'b, '1110'b, '1000'b = '1110 1110 1000'b = 'EE8'x, or one-and-a-half bytes (three nibbles). The space saving allows small devices, like portable memory keyers, to have more and longer International Morse code sequences in small, conventional device-driver [[microprocessor]]s' [[random access memory|RAM]] chips.

===Cable code===
The very long [[time constant]]s of 19th and early 20th&nbsp;century [[submarine communications cable]]s required a different form of Morse signalling. Instead of keying a voltage on and off for varying times, the dits and dahs were represented by two polarities of voltage impressed on the cable, for a uniform time.<ref name=Beauchamp-2001/>

===Timing===
Below is an illustration of timing conventions. The phrase '''{{sc|MORSE CODE}}''', in Morse code format, would normally be written something like this, where {{code|–}} represents ''dahs'' and {{code|·}} represents ''dits'':

<syntaxhighlight lang="text">
 −− −−− ·−· ··· ·       −·−· −−− −·· ·
 M   O   R   S  E        C    O   D  E
</syntaxhighlight>

Next is the exact conventional timing for this phrase, with {{code| ▓}} representing "signal on", and {{code|˽}} representing "signal off", each for the time length of exactly one dit:
{{disable VE top}}
{{smalldiv|1=
<syntaxhighlight lang="text">

          1         2         3         4         5         6         7         8
 12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789
 
  ———M———   —————O—————   ———R———   ——S——   E       —————C—————   —————O—————   ———D———   E
 
  ▓▓▓˽▓▓▓˽˽˽▓▓▓˽▓▓▓˽▓▓▓˽˽˽▓˽▓▓▓˽▓˽˽˽▓˽▓˽▓˽˽˽▓˽˽˽˽˽˽˽▓▓▓˽▓˽▓▓▓˽▓˽˽˽▓▓▓˽▓▓▓˽▓▓▓˽˽˽▓▓▓˽▓˽▓˽˽˽▓
     ↑           ↑        ↑       ↑             ↑
     |          dah      dit      |             |
 symbol space                letter space    word space

</syntaxhighlight>
}}
{{disable VE bottom}}

===Spoken representation===
Morse code is often spoken or written with ''dah'' for dashes, ''dit'' for dots located at the end of a character, and ''di'' for dots located at the beginning or internally within the character. Thus, the following Morse code sequence:
{{small| {{blockquote|
<syntaxhighlight lang="text">
M   O   R   S  E          C    O   D  E
−− −−− ·−· ··· · (space) −·−· −−− −·· ·
</syntaxhighlight>}} }}
is spoken (or sung):

{{small| {{blockquote|''{{nobr|Dah dah &emsp; dah dah dah &emsp; di dah dit &emsp; di di dit &emsp; dit, &emsp; }} &emsp; {{nobr| &emsp; Dah di dah dit &emsp; dah dah dah &emsp; dah di dit &emsp; dit. }}''}} }}

For use on radio, there is little point in learning to read ''written'' Morse as above; rather, the ''sounds'' of all of the letters and symbols need to be learned, for both sending and receiving.

===Speed in words per minute===
All Morse code elements depend on the dot / ''dit'' length. A ''dah'' is the length of 3&nbsp;dits (with no gaps between), and spacings are specified in number of ''dit'' lengths. An unambiguous method of specifying the transmission speed is to specify the ''dit'' duration as, for example, 50&nbsp;milliseconds.

Specifying the ''dit'' duration is, however, not the common practice. Usually, speeds are stated in words per minute. That introduces ambiguity because words have different numbers of characters, and characters have different ''dit'' lengths. It is not immediately clear how a specific word rate determines the ''dit'' duration in milliseconds.

Some method to standardize the transformation of a word rate to a ''dit'' duration is useful. A simple way to do this is to choose a ''dit'' duration that would send a typical word the desired number of times in one minute. If, for example, the operator wanted a character speed of 13&nbsp;words per minute, the operator would choose a ''dit'' rate that would send the typical word 13&nbsp;times in exactly one minute.

The typical word thus determines the ''dit'' length. It is common to assume that a word is 5&nbsp;characters long. There are two common typical words: '''{{sc|PARIS}}''' and '''{{sc|CODEX}}'''. '''{{sc|PARIS}}''' mimics a word rate that is typical of natural language words and reflects the benefits of Morse code's shorter code durations for common characters such as '''{{sc|e}}''' and '''{{sc|t}}'''. '''{{sc|CODEX}}''' offers a word rate that is typical of 5&nbsp;letter code groups (sequences of random letters). Using the word '''{{sc|PARIS}}''' as a standard, the number of ''dit'' units is 50 and a simple calculation shows that the ''dit'' length at 20&nbsp;words per minute is 60&nbsp;milliseconds. Using the word '''{{sc|CODEX}}''' with 60&nbsp;dit units, the ''dit'' length at 20&nbsp;words per minute is 50&nbsp;milliseconds.

Because Morse code is usually sent by hand, it is unlikely that an operator could be that precise with the ''dit'' length, and the individual characteristics and preferences of the operators usually override the standards.

For commercial radiotelegraph licenses in the United States, the Federal Communications Commission specifies tests for Morse code proficiency in words per minute and in code groups per minute.<ref name=US-CFR-Title-47/>{{rp|at=§13.207(c), §13.209(d)}} The [[FCC]] specifies that a "word" is 5&nbsp;characters long. The Commission specifies Morse code test elements at 16&nbsp;code groups per minute, 20&nbsp;words per minute, 20&nbsp;code groups per minute, and 25&nbsp;words per minute.<ref name=US-CFR-Title-47/>{{rp|at=§13.203(b)}} The word per minute rate would be close to the '''{{sc|PARIS}}''' standard, and the code groups per minute would be close to the '''{{sc|CODEX}}''' standard.

While the Federal Communications Commission no longer requires Morse code for amateur radio licenses, the old requirements were similar to the requirements for commercial radiotelegraph licenses.<ref name=US-CFR-Title-47/>{{rp|at=§97.503, 1996}}

A difference between amateur radio licenses and commercial radiotelegraph licenses is that commercial operators must be able to receive code groups of random characters along with plain language text. For each class of license, the code group speed requirement is slower than the plain language text requirement. For example, for the Radiotelegraph Operator License, the examinee must pass a 20&nbsp;word per minute plain text test and a 16&nbsp;word per minute code group test.<ref name=FCC-radiotelegraph/>

Based upon a 50&nbsp;dit duration standard word such as '''{{sc|PARIS}}''', the time for one ''dit'' duration or one unit can be computed by the formula:

:<math>~ T = \frac{\, 1,200 \,}{W} ~</math>

where: {{mvar|T}} is the unit time, or ''dit'' duration in milliseconds, and {{mvar|W}} is the speed in [[words per minute|{{sc|wpm}}]].

[[High-speed telegraphy]] contests are held; according to the ''[[Guinness Book of Records]]'' in June&nbsp;2005 at the [[International Amateur Radio Union]]'s 6th&nbsp;World Championship in High Speed Telegraphy in [[Primorsko]], Bulgaria, Andrei Bindasov of [[Belarus]] transmitted 230&nbsp;Morse code marks of mixed text in one minute.<ref name=Guinness-records-Morse/>

===Farnsworth speed===
Sometimes, especially while teaching Morse code, the timing rules above are changed so two different speeds are used: A character speed and a text speed. The character speed is how fast each individual letter is sent. The text speed is how fast the entire message is sent. For example, individual characters may be sent at a 13 words-per-minute rate, but the intercharacter and interword gaps may be lengthened so the word rate is only 5&nbsp;words per minute.

Using different character and text speeds is, in fact, a common practice, and is used in the Farnsworth method of [[#Learning methods|learning Morse code]].

===Alternative display of common characters in International Morse code===
{{See also|Huffman coding}}
Some methods of teaching Morse code use a [[dichotomic search]] table.
[[File:Morse code tree3.png|thumb|center|upright=3.5|International Morse code [[binary search]] tree: The graph branches left for each ''dit'' and right for each ''dah'' until the character representation is reached. Official [[International Telecommunication Union|ITU]] codes are shown as black letters on dark grey, and are complete, including punctuation; a few non-ITU extensions are shown in grey letters on light grey, but many others are left out. ITU [[Prosigns for Morse code|prosigns]] are circled in red with red text and are complete; unofficial prosigns are orange and are mostly complete.]]

== Learning methods ==
People learning Morse code using the ''Farnsworth method'' are taught to send and receive letters and other symbols at their full target speed, that is with normal relative timing of the ''dits'', ''dahs'', and spaces within each symbol for that speed. The Farnsworth method is named for Donald R. "Russ" Farnsworth, also known by his [[call sign]], W6TTB. However, initially exaggerated spaces between symbols and words are used, to give "thinking time" to make the sound "shape" of the letters and symbols easier to learn. The spacing can then be reduced with practice and familiarity.

Another popular teaching method is the '''Koch method''', invented in 1935 by the German engineer and former [[Sturmabteilung|stormtrooper]] Ludwig Koch,<ref>{{cite thesis |first=Ludwig |last=Koch |title=Arbeitspsychologische Untersuchung der Tätigkeit bei der Aufnahme von Morsezeichen |date=1936 |type=Dissertation |publisher=Technische Hochschule Carolo-Wilhelmina |url=https://www.qrpforum.de/index.php?attachment/23748-kochdissertation-pdf/ |id=10247-549-4}}</ref> which uses the full target speed from the outset but begins with just two characters. Once strings containing those two characters can be copied with 90% accuracy, an additional character is added, and so on until the full character set is mastered.

In North America, many thousands of individuals have increased their code recognition speed (after initial memorization of the characters) by listening to the regularly scheduled code practice transmissions broadcast by [[W1AW]], the American Radio Relay League's headquarters station.<ref>{{cite web |last1=AmericanRadio |first1=RelayLeague |title=W1AW Code Practice Schedule |url=http://www.arrl.org/w1aw-operating-schedule |website=ARRL |publisher=American Radio Relay League |access-date=3 June 2022}}</ref> {{As of|2015|post=,}} the United States military taught Morse code as an 81-day self-paced course, having phased out more traditional classes.<ref>{{Cite web|last=Linton|first=Tanja|date=April 30, 2015|title=Fort Huachuca bids farewell to Morse code training|url=https://www.army.mil/article/147247/fort_huachuca_bids_farewell_to_morse_code_training |access-date=2021-05-29|website=US Army }}</ref>

=== Mnemonics ===
{{main|Morse code mnemonics}}
[[File:Morse Code Mnemonic chart from Girl Guides handbook 1916.jpg|thumb|right|[[Scouting|Scout]] movement founder [[Robert Baden-Powell, 1st Baron Baden-Powell|Baden-Powell's]] mnemonic chart from 1918]]
Visual mnemonic charts have been devised over the ages. [[Robert Baden-Powell, 1st Baron Baden-Powell|Baden-Powell]] included one in the [[Girl Guides]] handbook<ref name=Baden-Powell-1938/> in 1918.

In the United Kingdom, many people learned the Morse code by means of a series of words or phrases that have the same rhythm as a Morse character. For instance, '''{{sc|Q}}''' in Morse is {{nowrap| ''dah dah di dah'' ,}} which can be memorized by the phrase "[[God Save the Queen]]", and the Morse for '''{{sc|F}}''' is {{nowrap| ''di di dah dit'' ,}} which can be memorized as "Did she like it?"{{efn|
A well-known Morse code rhythm from the Second World War period derives from [[Ludwig van Beethoven|Beethoven]]'s [[Symphony No. 5 (Beethoven)|Fifth Symphony]], the opening phrase of which was regularly played at the beginning of BBC broadcasts. The timing of the notes corresponds to the Morse for '''{{sc|V}}''', {{nowrap| ''di di di dah'' }} ({{morse|dot|dot|dot|dash}}), understood as ''"'V' for Victory"''<!-- (as well as the Roman numeral for the number five) -- inane -->.<ref name=Stanley-2000/><ref name=Studwell-1997/>
}}

{{clear}}

==Letters, numbers, punctuation, prosigns for Morse code and non-Latin variants==
{| class="wikitable sortable"
|- valign="top"
! Category || Character || Code
|- valign="top"
| Letters || '''[[A|A, a]]''' || {{audio|A morse code.ogg|{{morse|dot|dash}}}}
|- valign="top"
| Letters || '''[[B|B, b]]''' || {{audio|B morse code.ogg|{{morse|dash|dot|dot|dot}}}}
|- valign="top"
| Letters || '''[[C|C, c]]''' || {{audio|C morse code.ogg|{{morse|dash|dot|dash|dot}}}}
|- valign="top"
| Letters || '''[[D|D, d]]''' || {{audio|D morse code.ogg|{{morse|dash|dot|dot}}}}
|- valign="top"
| Letters || '''[[E|E, e]]''' || {{audio|E morse code.ogg|{{morse|dot}}}}
|- valign="top"
| Letters || '''[[F|F, f]]''' || {{audio|F morse code.ogg|{{morse|dot|dot|dash|dot}}}}
|- valign="top"
| Letters || '''[[G|G, g]]''' || {{audio|G morse code.ogg|{{morse|dash|dash|dot}}}}
|- valign="top"
| Letters || '''[[H|H, h]]''' || {{audio|H morse code.ogg|{{morse|dot|dot|dot|dot}}}}
|- valign="top"
| Letters || '''[[I|I, i]]''' || {{audio|I morse code.ogg|{{morse|dot|dot}}}}
|- valign="top"
| Letters || '''[[J|J, j]]''' || {{audio|J morse code.ogg|{{morse|dot|dash|dash|dash}}}}
|- valign="top"
| Letters || '''[[K|K, k]]''' <br/>[[Prosigns for Morse code|Prosign]] for general ''invitation to transmit'' || {{audio|K morse code.ogg|{{morse|dash|dot|dash}}}}
|- valign="top"
| Letters || '''[[L|L, l]]''' || {{audio|L morse code.ogg|{{morse|dot|dash|dot|dot}}}}
|- valign="top"
| Letters || '''[[M|M, m]]''' || {{audio|M morse code.ogg|{{morse|dash|dash}}}}
|- valign="top"
| Letters || '''[[N|N, n]]''' || {{audio|N morse code.ogg|{{morse|dash|dot}}}}
|- valign="top"
| Letters || '''[[O|O, o]]''' || {{audio|O morse code.ogg|{{morse|dash|dash|dash}}}}
|- valign="top"
| Letters || '''[[P|P, p]]''' || {{audio|P morse code.ogg|{{morse|dot|dash|dash|dot}}}}
|- valign="top"
| Letters || '''[[Q|Q, q]]''' || {{audio|Q morse code.ogg|{{morse|dash|dash|dot|dash}}}}
|- valign="top"
| Letters || '''[[R|R, r]]''' || {{audio|R morse code.ogg|{{morse|dot|dash|dot}}}}
|- valign="top"
| Letters || '''[[S|S, s]]''' || {{audio|S morse code.ogg|{{morse|dot|dot|dot}}}}
|- valign="top"
| Letters || '''[[T|T, t]]''' || {{audio|T morse code.ogg|{{morse|dash}}}}
|- valign="top"
| Letters || '''[[U|U, u]]''' || {{audio|U morse code.ogg|{{morse|dot|dot|dash}}}}
|- valign="top"
| Letters || '''[[V|V, v]]''' || {{audio|V morse code.ogg|{{morse|dot|dot|dot|dash}}}}
|- valign="top"
| Letters || '''[[W|W, w]]''' || {{audio|W morse code.ogg|{{morse|dot|dash|dash}}}}
|- valign="top"
| Letters || '''[[X|X, x]]''' || {{audio|X morse code.ogg|{{morse|dash|dot|dot|dash}}}}
|- valign="top"
| Letters || '''[[Y|Y, y]]''' || {{audio|Y morse code.ogg|{{morse|dash|dot|dash|dash}}}}
|- valign="top"
| Letters || '''[[Z|Z, z]]''' || {{audio|Z morse code.ogg|{{morse|dash|dash|dot|dot}}}}
|- valign="top"
| Numbers || '''[[0 (number)|0]]''' || {{audio|0 number morse code.ogg|{{morse|dash|dash|dash|dash|dash}}}}
|- valign="top"
| Numbers || '''[[1 (number)|1]]''' || {{audio|1 number morse code.ogg|{{morse|dot|dash|dash|dash|dash}}}}
|- valign="top"
| Numbers || '''[[2 (number)|2]]''' || {{audio|2 number morse code.ogg|{{morse|dot|dot|dash|dash|dash}}}}
|- valign="top"
| Numbers || '''[[3 (number)|3]]''' || {{audio|3 number morse code.ogg|{{morse|dot|dot|dot|dash|dash}}}}
|- valign="top"
| Numbers || '''[[4 (number)|4]]''' || {{audio|4 number morse code.ogg|{{morse|dot|dot|dot|dot|dash}}}}
|- valign="top"
| Numbers || '''[[5 (number)|5]]''' || {{audio|5 number morse code.ogg|{{morse|dot|dot|dot|dot|dot}}}}
|- valign="top"
| Numbers || '''[[6 (number)|6]]''' || {{audio|6 number morse code.ogg|{{morse|dash|dot|dot|dot|dot}}}}
|- valign="top"
| Numbers || '''[[7 (number)|7]]''' || {{audio|7 number morse code.ogg|{{morse|dash|dash|dot|dot|dot}}}}
|- valign="top"
| Numbers || '''[[8 (number)|8]]''' || {{audio|8 number morse code.ogg|{{morse|dash|dash|dash|dot|dot}}}}
|- valign="top"
| Numbers || '''[[9 (number)|9]]''' || {{audio|9 number morse code.ogg|{{morse|dash|dash|dash|dash|dot}}}}
|- valign="top"
| Punctuation || [[Full stop|'''Period''' ['''.''']<nowiki/>]] || {{audio|Morse Code - Period.ogg|{{morse|dot|dash|dot|dash|dot|dash}}}}
|- valign="top"
| Punctuation || [[Comma (punctuation)|'''Comma''' [''',''']<nowiki/>]] || {{audio|Morse Code - Comma.ogg|{{morse|dash|dash|dot|dot|dash|dash}}}}
|- valign="top"
| Punctuation || [[Question mark|'''Question mark''' ['''?''']<nowiki/>]] || {{audio|Morse Code - Question Mark.ogg|{{morse|dot|dot|dash|dash|dot|dot}}}}
|- valign="top"
| Punctuation || [[Apostrophe (punctuation)|'''Apostrophe''' ['''<nowiki/>'<nowiki/>''']<nowiki/>]] || {{audio|Morse Code - Apostrope.ogg|{{morse|dot|dash|dash|dash|dash|dot}}}}
|- valign="top"
| Nonstandard <br/> punctuation{{efn|name=not-in-either-ITU-R}} || [[Exclamation mark|'''Exclamation point''' ['''!''']<nowiki/>]] <br/> {{sc| {{overline|KW}} }} [[Digraph (orthography)|digraph]] || {{audio|Morse Code - Exclamation Point.ogg|{{morse|dash|dot|dash|dot|dash|dash}}}}
|- valign="top"
| Punctuation || [[Slash (punctuation)|'''Slash''']] or [[Fraction (mathematics)|'''Fraction bar''' ['''/''']<nowiki/>]] <br/> {{sc| {{overline|DN}} }} [[Digraph (orthography)|digraph]] || {{audio|Morse Code - Slash.ogg|{{morse|dash|dot|dot|dash|dot}}}}
|- valign="top"
| Punctuation || [[Parenthesis|'''Open parenthesis''' ['''(''']<nowiki/>]] <br/> {{sc| {{overline|KN}} }} [[Digraph (orthography)|digraph]] &emsp; Unofficial [[Prosigns for Morse code|prosign]] for '''''exclusive''' invitation to transmit'' || {{audio|Morse Code - Parenthesis (Open).ogg|{{morse|dash|dot|dash|dash|dot}}}}
|- valign="top"
| Punctuation || [[Parenthesis|'''Close parenthesis''' [''')''']<nowiki/>]] <br/> {{sc| {{overline|KK}} }} [[Digraph (orthography)|digraph]] || {{audio|Morse Code - Parenthesis (Close).ogg|{{morse|dash|dot|dash|dash|dot|dash}}}}
|- valign="top"
| Nonstandard<br/>punctuation{{efn|name=not-in-either-ITU-R}} || '''[[Ampersand]]''' ['''&''']{{efn|name=E_S_for_&_note}} <br/> {{sc| {{overline|AS}} }} [[Digraph (orthography)|digraph]] &emsp; [[Prosigns for Morse code|Prosign]] for ''wait'' || {{audio|Morse Code - Ampersand.ogg|{{morse|dot|dash|dot|dot|dot}}}}
|- valign="top"
| Punctuation || [[Colon (punctuation)|'''Colon''' [''':''']<nowiki/>]] || {{audio|Morse Code - Colon.ogg|{{morse|dash|dash|dash|dot|dot|dot}}}}
|- valign="top"
| Nonstandard<br/>punctuation{{efn|name=not-in-either-ITU-R|<br/>The character or symbol encoding is not in either [[ITU-R]]&nbsp;M.1172<ref name=ITU-R-M-1172/> or [[ITU-R]]&nbsp;M.1677-1&nbsp;.<ref name=ITU-R-M-1677/>}} || [[Semicolon|'''Semicolon''' [''';''']<nowiki/>]] || {{audio|Morse Code - Semicolon.ogg|{{morse|dash|dot|dash|dot|dash|dot}}}}
|- valign="top"
| Punctuation || [[Equal sign|'''Double dash''' ['''=''']<nowiki/>]] <br/> {{sc| {{overline|BT}} }} [[Digraph (orthography)|digraph]] &emsp; [[Prosigns for Morse code|Prosign]] for ''new section'' or ''new paragraph'' || {{audio|Morse Code - Equals.ogg|{{morse|dash|dot|dot|dot|dash}}}}
|- valign="top"
| Punctuation || [[Plus and minus signs|'''Plus sign''' ['''+''']<nowiki/>]] <br/> {{sc| {{overline|RN}} }} [[Digraph (orthography)|digraph]] &emsp; [[Prosigns for Morse code|Prosign]] for ''new message'' or ''new page'' || {{audio|Morse Code - Plus.ogg|{{morse|dot|dash|dot|dash|dot}}}}
|- valign="top"
| Punctuation || '''[[Hyphen]]''' or [[Plus and minus signs|'''Minus sign''' ['''-''']<nowiki/>]] || {{audio|Morse Code - Hyphen, Minus.ogg|{{morse|dash|dot|dot|dot|dot|dash}}}}
|- valign="top"
| Nonstandard<br/>punctuation{{efn|name=not-in-either-ITU-R}} || [[Underscore|'''Underscore''' [ '''_''' ]<nowiki/>]] || {{audio|Morse Code - Underscore.ogg|{{morse|dot|dot|dash|dash|dot|dash}}}}
|- valign="top"
| Punctuation || [[Quotation mark|'''Quotation mark''' ['''"''']<nowiki/>]] || {{audio|Morse Code - Quotation_Mark.ogg|{{morse|dot|dash|dot|dot|dash|dot}}}}
|- valign="top"
| Nonstandard <br/> punctuation{{efn|name=not-in-either-ITU-R}} || [[Dollar sign|'''Dollar sign''' ['''$''']<nowiki/>]] <br/> {{sc| {{overline|SX}} }} [[Digraph (orthography)|digraph]] || {{audio|Morse Code - Dollar Sign.ogg|{{morse|dot|dot|dot|dash|dot|dot|dash}}}}
|- valign="top"
| Punctuation || [[Commercial at|'''At sign''' ['''@''']<nowiki/>]] <br/> {{sc| {{overline|AC}} }} [[Digraph (orthography)|digraph]] || {{audio|Morse Code - At (Commercial At).ogg|{{morse|dot|dash|dash|dot|dash|dot}}}}
|- valign="top"
| [[Prosigns for Morse code|Prosigns]] || '''End of work''' <br/> {{sc| {{overline|SK}} }} [[Digraph (orthography)|digraph]]|| {{audio|Morse Prosign - End of Work.oga|{{morse|dot|dot|dot|dash|dot|dash}}}}
|- valign="top"
| [[Prosigns for Morse code|Prosigns]] || '''Error''' <br/> {{sc| {{overline|HH}} }} [[Digraph (orthography)|digraph]] || {{audio|Morse Prosign - Error.oga|{{morse|dot|dot|dot|dot|dot|dot|dot|dot}}}}
|- valign="top"
| [[Prosigns for Morse code|Prosigns]] || '''General invitation to transmit''' <br/> Also used for letter '''K''' || {{audio|Morse Prosign - Invitation to Transmit.oga|{{morse|dash|dot|dash}}}}
|- valign="top"
| [[Prosigns for Morse code|Prosigns]] || '''Starting signal''' <br/> {{sc| {{overline|CT}} }} [[Digraph (orthography)|digraph]] || {{audio|Morse Prosign - Starting Signal.oga|{{morse|dash|dot|dash|dot|dash}}}}
|- valign="top"
| [[Prosigns for Morse code|Prosigns]] || '''New message follows''' <br/> {{sc|  {{overline|RN}} }} [[Digraph (orthography)|digraph]] &emsp; Message or page separator{{efn|Single-line decoding display may use printed "+" for message separator prosign.}} || {{audio|Morse Code - Plus.ogg|{{morse|dot|dash|dot|dash|dot}}}}
|- valign="top"
| [[Prosigns for Morse code|Prosigns]] || '''Verified''' <br/> Also used for letter '''Ŝ''' || {{audio|Morse Prosign - Understood.oga|{{morse|dot|dot|dot|dash|dot}}}}
|- valign="top"
| [[Prosigns for Morse code|Prosigns]] || '''Wait''' <br/> Proposed for use as [[ampersand]]&nbsp;['''&''']{{efn|
name=E_S_for_&_note|
The well-established standard abbreviation for "and" is {{nobr|'''{{sc|E S}}''',}} adapted from the code for [[ampersand]] in [[American Morse Code|Railroad Morse]]. The code for  {{nobr|'''{{sc|E S}}'''}} {{nobr|({{morse|dot}}{{morse|dot|dot|dot}} ) }} is actually slightly shorter in duration than the '''wait''' prosign {{nobr|({{morse|dot|dash|dot|dot|dot}} ),}} so there is no motivative to replace it.
}} || {{audio|Morse Prosign - Wait.oga|{{morse|dot|dash|dot|dot|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[À|À, à]]''' <br/> Code shared with '''Å''' || {{audio|À, Å morse code.oga|{{morse|dot|dash|dash|dot|dash}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ä|Ä, ä]]''' <br/> Code shared with '''Æ''', '''Ą''' || {{audio|Ä, Æ, Ą morse code.oga|{{morse|dot|dash|dot|dash}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Å|Å, å]]''' <br/> Code shared with '''À''' || {{audio|À, Å morse code.oga|{{morse|dot|dash|dash|dot|dash}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ą|Ą, ą]]''' <br/> Code shared with '''Ä''', '''Æ''' || {{audio|Ä, Æ, Ą morse code.oga|{{morse|dot|dash|dot|dash}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Æ|Æ, æ]]''' <br/> Code shared with '''Ä''', '''Ą''' || {{audio|Ä, Æ, Ą morse code.oga|{{morse|dot|dash|dot|dash}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ć|Ć, ć]]''' <br/> Code shared with '''Ĉ''', '''Ç''' || {{audio|Ç,Ĉ,Ć Morse Code.oga|{{morse|dash|dot|dash|dot|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ĉ|Ĉ, ĉ]]''' <br/> Code shared with '''Ć''',  '''Ç''' || {{audio|Ç,Ĉ,Ć Morse Code.oga|{{morse|dash|dot|dash|dot|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ç|Ç, ç]]''' <br/> Code shared with '''Ć''', '''Ĉ''' || {{audio|Ç,Ĉ,Ć Morse Code.oga|{{morse|dash|dot|dash|dot|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ch (digraph)|CH, ch]]''' <br/> Code shared with '''Ĥ''', '''Š''' || {{audio|CH, Ĥ, Š Morse Code.oga|{{morse|dash|dash|dash|dash}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Đ|Đ, đ]]''' <br/> Code shared with '''É'''{{efn|name=solo-É}}, '''Ę''' &emsp; Distinct from [[Eth|''eth'' ('''Ð''', '''ð''')]] || {{audio|É, đ, Ę Morse Code.oga|{{morse|dot|dot|dash|dot|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ð|Ð, ð]]''' <br/> Distinct from [[D with stroke|D with stroke ('''Đ''', '''đ''')]] || {{audio|Ð Morse Code.oga|{{morse|dot|dot|dash|dash|dot}}}}
|- valign="top"
| non-Latin<br/>extensions || '''[[É|É, é]]'''{{efn|name=solo-É|Although not strictly a [[Latin alphabet]] character, the code for '''É''' is part of the [[ITU-R]] Morse code standard, and is the only accented character included in the recommendation.<ref name=ITU-R-M-1677/>}} <br/> Code shared with '''Đ''', '''Ę''' || {{audio|É, đ, Ę Morse Code.oga|{{morse|dot|dot|dash|dot|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[È|È, è]]''' <br/> Code shared with '''Ł''' || {{audio|È, Ł Morse Code.oga|{{morse|dot|dash|dot|dot|dash}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ę|Ę, ę]]''' <br/> Code shared with '''Đ''', '''É'''{{efn|name=solo-É}} || {{audio|É, đ, Ę Morse Code.oga|{{morse|dot|dot|dash|dot|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ĝ|Ĝ, ĝ]]''' || {{audio|Ĝ Morse Code.oga|{{morse|dash|dash|dot|dash|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ĥ|Ĥ, ĥ]]''' <br/> Code shared with '''CH''',  '''Š''' || {{audio|CH, Ĥ, Š Morse Code.oga|{{morse|dash|dash|dash|dash}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ĵ|Ĵ, ĵ]]''' || {{audio|Ĵ Morse Code.oga|{{morse|dot|dash|dash|dash|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ł|Ł, ł]]''' <br/> Code shared with '''È''' || {{audio|È, Ł Morse Code.oga|{{morse|dot|dash|dot|dot|dash}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ń|Ń, ń]]''' <br/> Code shared with '''Ñ''' || {{audio|Ñ, Ń Morse Code.oga|{{morse|dash|dash|dot|dash|dash}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ñ|Ñ, ñ]]''' <br/> Code shared with '''Ń''' || {{audio|Ñ, Ń Morse Code.oga|{{morse|dash|dash|dot|dash|dash}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ó|Ó, ó]]''' <br/> Code shared with '''Ö''', '''Ø''' || {{audio|Ö, Ø, Ó Morse Code.oga|{{morse|dash|dash|dash|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ö|Ö, ö]]''' <br/> Code shared with '''Ó''', '''Ø''' || {{audio|Ö, Ø, Ó Morse Code.oga|{{morse|dash|dash|dash|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ø|Ø, ø]]''' <br/> Code shared with '''Ó''', '''Ö''' || {{audio|Ö, Ø, Ó Morse Code.oga|{{morse|dash|dash|dash|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ś|Ś, ś]]''' || {{audio|Ś Morse Code.oga|{{morse|dot|dot|dot|dash|dot|dot|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ŝ|Ŝ, ŝ]]''' <br/> [[Prosigns for Morse code|Prosign]] for ''verified'' || {{audio|Ŝ Morse Code.oga|{{morse|dot|dot|dot|dash|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Š|Š, š]]''' <br/> Code shared with '''CH''', '''Ĥ''' || {{audio|CH, Ĥ, Š Morse Code.oga|{{morse|dash|dash|dash|dash}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Þ|Þ, þ]]''' || {{audio|Þ Morse Code.oga|{{morse|dot|dash|dash|dot|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ü|Ü, ü]]''' <br/> Code shared with '''Ŭ''' || {{audio|Ü, Ŭ Morse Code.oga|{{morse|dot|dot|dash|dash}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ŭ|Ŭ, ŭ]]''' <br/> Code shared with '''Ü''' || {{audio|Ü, Ŭ Morse Code.oga|{{morse|dot|dot|dash|dash}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ź|Ź, ź]]''' || {{audio|Ź Morse Code.oga|{{morse|dash|dash|dot|dot|dash|dot}}}}
|- valign="top"
| non-Latin{{efn|name=not-in-either-ITU-R}}<br/>extensions || '''[[Ż|Ż, ż]]''' || {{audio|Ż Morse Code.oga|{{morse|dash|dash|dot|dot|dash}}}}
|}

=== Cut numbers ===
Most numbers have an unofficial short-form, given in the table below. They are only used when both the sender and the receiver understand that numbers, and not letters, are intended;{{citation needed|date=October 2023}} for example, one often sees the most common [[R-S-T system|R-S-T signal report]] rendered as '''5{{sc|NN}}'''{{sup|[‡]}} instead of '''599'''.{{citation needed|date=October 2023}}

:{| class="wikitable"
|+ {{big| Cut numbers }}<br/>{{citation needed|date=October 2023}}
|-
! &ensp; Intended &emsp; <br/>&ensp; digit &emsp; 
! &ensp; 'Cut' number <br/>&ensp; code 
! &emsp; {{grey| Same as code in &emsp; <br/> &ensp; &ensp; Intl. Morse }}{{sup|[}}*{{sup|]}} &emsp; 
! {{grey| Normal code &emsp; <br/> &ensp; &ensp; (long form) }}{{sup|[}}*{{sup|]}} &emsp; 
|-
!  0 
|  &ensp; {{morse|dash}} 
|style="text-align:center;"|  {{grey|'''{{sc|T}}'''}}
|  &thinsp; {{grey| {{morse|dash|dash|dash|dash|dash}} }}
|- 
!  1 
|  &ensp; {{morse|dot|dash}} 
|style="text-align:center;"|  {{grey|'''{{sc|A}}'''}}
|  &thinsp; {{grey| {{morse|dot|dash|dash|dash|dash}} }}
|-
!  2 
|  &ensp; {{morse|dot|dot|dash}} 
|style="text-align:center;"|  {{grey|'''{{sc|U}}'''}}
|  &thinsp; {{grey| {{morse|dot|dot|dash|dash|dash}} }}
|-
!  3 
| &ensp; {{morse|dot|dot|dot|dash}} 
|style="text-align:center;"|  {{grey|'''{{sc|V}}'''}}
| &thinsp; {{grey| {{morse|dot|dot|dot|dash|dash}} }}
|-
!  4 
|  &emsp; {{grey|n/a}}{{sup|[†]}} 
|style="text-align:center;"|  &emsp; '''4'''{{sup|[†]}}  
|  &thinsp; {{morse|dot|dot|dot|dot|dash}}{{sup|[†]}}
|-
!  5 
|  &ensp; {{morse|dot}}{{sup|[‡]}} 
|style="text-align:center;"|  {{grey|'''{{sc|e}}'''}} or '''5'''{{sup|[‡]}} &ensp;
|  &thinsp; {{morse|dot|dot|dot|dot|dot}}{{sup|[‡]}} 
|-
!  6 
|  &emsp; {{grey|n/a}}{{sup|[†]}} 
|style="text-align:center;"|  &emsp; '''6'''{{sup|[†]}}  
|  &thinsp; {{morse|dash|dot|dot|dot|dot}}{{sup|[†]}}
|-
!  7  
|  &ensp; {{morse|dash|dot|dot|dot}} 
|style="text-align:center;"|  {{grey|'''{{sc|B}}'''}}
|  &thinsp; {{grey| {{morse|dash|dash|dot|dot|dot}} }}
|-
!  8 
|  &ensp; {{morse|dash|dot|dot}} 
|style="text-align:center;"|  {{grey|'''{{sc|D}}'''}}
|  &thinsp; {{grey| {{morse|dash|dash|dash|dot|dot}} }}
|-
!  9 
|  &ensp; {{morse|dash|dot}} 
|style="text-align:center;"|  {{grey|'''{{sc|N}}'''}}
|  &thinsp; {{grey| {{morse|dash|dash|dash|dash|dot}} }}
|-
|colspan=4 style="height:1px;"| 
|-
!  {{big|'''.'''}} 
|  &ensp; {{morse|dash|dot|dash}} 
|style="text-align:center;"|  {{grey|'''{{sc|K}}'''}}
|  &thinsp; {{grey| {{morse|dot|dash|dot|dash|dot|dash}} }}
|}

:{|
|-  style="vertical-align:top;"
!  &emsp; !!style="text-align:left;"| {{big| Table notes }}<br/>
|-  style="vertical-align:top;"
|style="text-align:center;"|  [*]&emsp;  || Codes that are ''not'' cut numbers, or are not numbers, are {{grey|'''shaded grey'''}} in the table.
|-  style="vertical-align:top;"
|style="text-align:center;"|  [†]&emsp;  || There are no distinct cut-number codes for '''4''' or '''6''', since cut numbers come from reducing multiple ''dahs'' in the standard Morse number codes to only one ''dah'', but keeping all the ''dits'' as-is.
|-  style="vertical-align:top;"
|style="text-align:center;"|  [‡]&emsp;  ||  Some operators just send the normal code for '''5''', even when using other cut numbers, since five ''dits'' are still fairly short (same duration as cut&nbsp;'''3''' and cut&nbsp;'''7'''), and a single ''dit'' could possibly be misinterpreted as a mistaken cut&nbsp;'''1''' or cut decimal point.{{citation needed|date=October 2023}}
|}

=== Prosigns ===
{{main|Prosigns for Morse code}}
Prosigns for Morse code are special (usually) unwritten procedural signals or symbols that are used to indicate changes in [[communications protocol]] status or [[white space (visual arts)|white space]] text formatting actions.

=== Symbol representations ===
The symbols ['''!'''], ['''$'''], and ['''&'''] are not defined inside the official [[ITU-R]] ''International Morse Code Recommendation'',<ref name=ITU-R-M-1677/> but informal conventions for them exist. (The ['''@'''] symbol was formally added in 2004.)

; Exclamation mark : There is no standard representation for the exclamation mark ['''!'''], although the {{sc| {{overline|KW}} }} [[Digraph (orthography)|digraph]] ({{morse|dash|dot|dash|dot|dash|dash}}) was proposed in the 1980s by the [[Heathkit]] Company.{{efn|[[Heathkit]] was a popular, long-standing vendor of kits for amateur radio equipment.}} While Morse code translation software prefers the Heathkit version, on-air use is not yet universal as some amateur radio operators in North America and the Caribbean continue to use the older {{sc| {{overline|MN}} }} digraph ({{morse|dash|dash|dash|dot}}){{efn| {{sc| {{overline|MN}} }} or {{sc| {{overline|OE}} }}, {{morse|dash|dash|dash|dot}}, is shared with unofficial '''{{sc|Ö}}''', '''{{sc|Ó}}''', and '''{{sc|Ø}}''' used in some non-Latin alphabets.}} copied over from [[American Morse code|American Morse landline code]].
; Currency symbols : The ITU has never formally codified any [[currency symbol]]s into Morse code: The unambiguous [[ISO 4217]] currency codes are preferred for transmission.
: The ['''$'''] sign code was represented in the [[Phillips Code]]{{efn|The [[Phillips Code]] was a huge collection of abbreviations used on land line telegraphy.}} as two characters "'''{{sc|SX}}'''", which became merged into {{sc| {{overline|SX}} }} ({{morse|dot|dot|dot|dash|dot|dot|dash}}).
; Ampersand [&] : The suggested unofficial encoding of the [[ampersand]] ['''&'''] sign listed above,{{efn|name=E_S_for_&_note}} often shown as {{sc| {{overline|AS}} }}, is also the official Morse [[Prosigns for Morse code|prosign]] for ''wait''. In addition, the [[American Morse code|American Morse encoding]] for an ampersand ({{morse|dot|aspace|dot|dot|dot}}) was similar to '''{{sc|ES}}''' ({{morse|dot}}{{morse|dot|dot|dot}}) and [[Amateur radio operators|hams]] have nearly universally carried over this use as an abbreviation for "and" (e.g. '''{{sc|WX HR COLD ES RAINY}}''' ''the weather here is cold and rainy'').
; Keyboard "at" sign [@] : On 24&nbsp;May 2004 – the 160th&nbsp;anniversary of the first public Morse telegraph transmission – the Radiocommunication Bureau of the International Telecommunication Union ([[ITU-R]]) formally added the ['''@'''] ("[[commercial at]]" or "commat") character to the official Morse character set, using the sequence denoted by the {{sc| {{overline|AC}} }} digraph: {{morse|dot|dash|dash|dot|dash|dot}}&nbsp;.<ref name=ITU-R-M-1677/><ref name=ARRL-News-2003-12-10/>
: This sequence was reported to have been chosen to represent "A[t] C[ommercial]", or a letter "a" inside a swirl represented by a letter "C". The new character facilitates sending [[email|e‑mail]] addresses by Morse code, and is notable since it is the first official addition to the Morse set of characters since [[World War I]].<ref name=ARRL-News-2003-12-10/>

===Diacritics and non-Latin extensions <span class="anchor" id="Non-Latin extensions"></span>===
{{Main|Morse code for non-Latin alphabets}}
The typical tactic for creating Morse codes for [[diacritic]]s and non-[[Latin alphabet|Latin]] alphabetic scripts has been to begin by simply using the International Morse codes used for letters whose sound matches the sound of the local alphabet. Because [[Gerke code]] (the predecessor to International Morse) was in official use in central Europe,<ref name=Deutsch-Österreich-Telegr-1851/> and included four characters not included in the International Morse standard ('''{{sc|Ä}}''', '''{{sc|Ö}}''', '''{{sc|Ü}}''', and '''{{sc|CH}}''') it has served as a beginning-point for other languages that use an [[alphabet]]ic script, but require codes for letters not accommodated by International Morse.

The usual method has been to first transliterate the sounds represented by the International code and the four unique Gerke codes into the local alphabet, hence [[Morse code for non-Latin alphabets|Greek, Hebrew]], [[Russian Morse code|Russian, and Ukrainian]] Morse codes. If more codes are needed, one can either invent a new code or convert an otherwise unused code from either code set to the non-Latin letter. For example:
* '''{{sc|[[Ñ]]}}''' in Spanish Morse is {{morse|dash|dash|dot|dash|dash}}, a language-specific code not used in either International or Gerke Morse.
* For the Greek letter {{char|[[Ψ]]}}, [[Morse code for non-Latin alphabets|Greek Morse code]] uses the International Morse code for '''{{sc|[[Q]]}}''', {{morse|dash|dash|dot|dash}}, which has no corresponding letter in modern Greek; {{char|[[Ψ]]}} and {{char|[[Q]]}} have no historical, phonetic, or shape relationship.

For [[Russian language|Russian]] and Bulgarian, [[Russian Morse code]] is used to map the Cyrillic characters to four-element codes. Many of the characters are encoded the same as their latin-alphabet look-alikes or sound-alikes ('''{{sc|A}}''', '''{{sc|O}}''', '''{{sc|E}}''', '''{{sc|I}}''', '''{{sc|T}}''', '''{{sc|M}}''', '''{{sc|N}}''', '''{{sc|R}}''', '''{{sc|K}}''', etc.). The Bulgarian alphabet contains 30&nbsp;characters, which exactly match all possible combinations of 1, 2, 3, and 4&nbsp;''dits'' and ''dahs'' (Russian '''{{sc|Ы}}''' is used as Bulgarian '''{{sc|Ь}}''', Russian '''{{sc|Ь}}''' is used as Bulgarian '''{{sc|Ъ}}'''). Russian requires two more codes, for letters '''{{sc|[[Э]]}}''' and '''{{sc|[[Ъ]]}}''' which are each encoded with 5&nbsp;elements.

Non-[[alphabet]]ic scripts require more radical adaption. Japanese Morse code ([[Wabun code]]) has a separate encoding for [[kana]] script; although many of the codes are used for International Morse, the sounds they represent are mostly unrelated. The Japanese / [[Wabun code|Wabun]] code includes special [[Prosigns for Morse code|prosigns]] for switching back-and-forth from International Morse: {{morse|dash|dot|dot|dash|dash|dash}} signals a switch from International Morse to [[Wabun code|Wabun]], and {{morse|dot|dot|dot|dash|dot}} to return from [[Wabun code|Wabun]] to International Morse.

For [[Chinese language|Chinese]], [[Chinese telegraph code]] is used to map [[Chinese characters]] to four-digit codes and send these digits out using standard Morse code. Korean Morse code<ref name=dik-archive/> uses the SKATS mapping, originally developed to allow Korean to be typed on western typewriters. SKATS maps [[hangul]] characters to arbitrary letters of the [[Latin script]] and has no relationship to pronunciation in [[Korean language|Korean]].

=== Unusual variants ===
During early World War&nbsp;I (1914–1916), Germany briefly experimented with 'dotty' and 'dashy' Morse, in essence adding a dot or a dash at the end of each Morse symbol. Each one was quickly broken by Allied SIGINT, and standard Morse was resumed by Spring&nbsp;1916. Only a small percentage of Western Front ([[North Atlantic]] and [[Mediterranean Sea]]) traffic was in 'dotty' or 'dashy' Morse during the entire war. In popular culture, this is mostly remembered in the book ''[[The Codebreakers]]'' by [[David Kahn (writer)|David Kahn]] and in the national archives of the UK and Australia (whose [[SIGINT]] operators copied most of this Morse variant). Kahn's cited sources come from the popular press and wireless magazines of the time.<ref name=Wythoff-2014/>

Other variations include forms of "fractional Morse" or "fractionated Morse", which recombine the characters of the Morse code{{endash}}encoded message and then encrypt them using a cipher in order to disguise the text.<ref name=Quadibloc-pp1323/>

==Decoding software==
Decoding software for Morse code ranges from software-defined wide-band radio receivers, coupled to the Reverse Beacon Network,<ref name=Reverse-Beacon/> which decodes signals and detects '''{{sc|CQ}}''' messages on [[Amateur radio frequency allocations|ham bands]], to smartphone applications.<ref name=Ziegenhain-2013/>

==See also==
{{columns-list|colwidth=15em|
* [[ACP 131]]
* [[Alfred Vail]]
* [[The CW Operators' Club|CW Operators' Club]]
* [[Guglielmo Marconi]]
* [[High-speed telegraphy]]
* [[Hog-Morse]]
* [[Instructograph]]
* [[Morse code abbreviations]]
* [[Morse code mnemonics]]
* [[NATO phonetic alphabet]]
* [[Radio code]]
* [[Tap code]]
* [[Wabun code]]
* [[Wireless telegraphy]]
}}

==Footnotes==
{{notelist}}

==References==
{{reflist|25em|refs=

<ref name=Anson-2018>
{{cite book
 |first=Denis K. |last=Anson
 |year=2018
 |chapter=Chapter&nbsp;5. Input strategies: Morse strategies
 |chapter-url={{GBurl|WAVnDwAAQBAJ|p=74}}
 |title=Assitive Technology for People with Disabilies
 |publisher=ABC-CLIO
 |isbn=978-1-4408-3512-4
 |page=74
}}
</ref>

<ref name=Army-1939-FM-24-5>
{{cite book
 |publisher=U.S. Army
 |department=Signal Corps
 |year=1939
 |title=Signal Communication
 |id=FM 24-5
 |pages=83, 101–108, 227
 |url=https://archive.org/details/Fm24-5-nsia/page/n1
}}
</ref>

<ref name=Army-1968-TM-11-459>
{{cite book
 |title= TM 11-459. International Morse Code (Instructions)
 |year=1968
 |pages=6–7
 |place=Washington, DC
 |publisher=Department of the Army / U.S. Government Printing Office
 |url=https://archive.org/details/us-army-11-459/page/n3
}}
</ref>

<ref name=ARRL-2000-Part-97-amended>
{{cite web
 | title=Amendment of Part&nbsp;97 of the Commission's Amateur Service Rules
 | series=1998 Biennial Regulatory Review
 | year= c. 2000
 | url=http://www.arrl.org/announce/regulatory/wt98-143ro.pdf
 | access-date=December 4, 2005
 |archive-url = https://web.archive.org/web/20051031180705/http://www.arrl.org/announce/regulatory/wt98-143ro.pdf <!-- Bot retrieved archive -->
 |archive-date = October 31, 2005
}}
</ref>

<ref name=ARRL-Learning-Morse>
{{cite web
 |title=Learning Morse code
 |website=Arrl.org
 |place=Newington, CT
 |publisher=[[American Radio Relay League]]
 |url=http://www.arrl.org/learning-morse-code
 |access-date=1 December 2017  |url-status=live
 |archive-url=https://web.archive.org/web/20170920205038/http://www.arrl.org/Learning-Morse-Code
 |archive-date=20 September 2017
}}
</ref>

<ref name=ARRL-Letter-2005-08-12>
{{cite news
 | title = Italy joins no-code ranks as FCC revives Morse debate in the U.S.
 | date = August 12, 2005
 | periodical = The ARRL Letter
 | volume = 24  | number = 31
 | url = http://www.arrl.org/arrlletter?issue=2005-08-12
 | access-date = 2012-04-02 | url-status=live
 | archive-url = https://web.archive.org/web/20111105103738/http://www.arrl.org/arrlletter?issue=2005-08-12
 | archive-date = November 5, 2011
}}
</ref>

<ref name=ARRL-News-2003-12-10>
{{cite news
 | title = International Morse code gets a new ITU home, new character
 | date = 2003-12-10
 | website = ARRL.org/news
 | place = Newington, CT
 | publisher = [[American Radio Relay League]]
 | url = http://www.arrl.org/news/stories/2003/12/10/2/?nc=1
 | access-date = 2007-02-27
 | archive-url = https://web.archive.org/web/20070930203318/http://www.arrl.org/news/stories/2003/12/10/2/?nc=1 <!-- Bot retrieved archive -->
 | archive-date = 2007-09-30
}}
</ref>

<ref name=ARRL-x9004008-Farnsw>
{{cite web
 |title=A standard for Morse timing using the Farnsworth technique
 |website=ARRL.org
 |url=http://www.arrl.org/files/file/Technology/x9004008.pdf
 |access-date=1 December 2017  |url-status=live
 |archive-url=https://web.archive.org/web/20180125150630/http://www.arrl.org/files/file/Technology/x9004008.pdf
 |archive-date=25 January 2018
}}
</ref>

<ref name=Baden-Powell-1938>
{{cite web
 |first=Robert |last=Baden-Powell |author-link=Robert Baden-Powell, 1st Baron Baden-Powell
 |date=1938
 |title=Girl Guiding
 |publisher=Pearson
 |page=61
 |url=http://oldscoutbooks.com/girlguiding.pdf
 |url-status=live  |access-date=2015-09-06
 |archive-url=https://web.archive.org/web/20151006042341/http://oldscoutbooks.com/girlguiding.pdf
 |archive-date=2015-10-06
 |quote=Some people find it easier to remember the [dots] and dashes by picturing them as forming the letters&nbsp;...{{rp|style=ama|at=page 61}}
}}
</ref>

<ref name=Beauchamp-2001>
{{cite book
 |first=Ken  |last=Beauchamp
 |year=2001
 |title=History of Telegraphy
 |publisher=Institution of Electrical Engineers IET
 |isbn=0852967926
 |page=150
}}
</ref>

<ref name=Beechey-1876>
{{cite book
 |first=F.S. |last=Beechey
 |year=1876
 |title=Electro-Telegraphy
 |page=71
 |place=London, UK
 |publisher=E. & F.N. Spon
 |url=https://archive.org/details/electrotelegrap00beecgoog/page/n74
 |via=Archive.org
}}
</ref>

<ref name=Burch-1990-07>
{{cite magazine
 |first=Donna |last=Burch
 |date=July 1990
 |title=Morse code from the heart
 |magazine=[[QST magazine]]
 |page=45
}}
</ref>

<ref name=Burns-2004>
{{cite book
 |first=R.W. |last=Burns
 |year=2004
 |title=Communications: An international history of the formative years
 |pages=79, 84
 |publisher=Institution of Electrical Engineers
 |isbn=0-86341-327-7
}}
</ref>

<ref name=Camm-1941>
{{cite book
 |first=F.J. |last=Camm
 |year=1941
 |title=Radio Engineers' Pocket Book
 |edition=2nd  |page=72
 |publisher=Chemical Publishing Co.
 |url=https://archive.org/details/RadioEngineersPocketBook/page/n71
 |via=Archive.org
}}
</ref>

<ref name=Canada-AIM-2003-COM-3-2>
{{cite web
 |title=COM&nbsp;3.2
 |series=Canadian AIM
 |year=2003
 |url=http://www.tc.gc.ca/media/documents/ca-publications/COM-AIM-2013-2_ENG-3.pdf
 |url-status=dead
 |archive-url=https://web.archive.org/web/20131122080042/http://www.tc.gc.ca/media/documents/ca-publications/COM-AIM-2013-2_ENG-3.pdf
 |archive-date=November 22, 2013
}}
</ref>

<ref name=Carron-1986>
{{cite book
 |first=L. Peter |last=Carron
 |year=1986
 |title=Morse Code: The essential language
 |series=Radio amateur's library  |volume=69
 |publisher=[[American Radio Relay League]]
 |isbn=0-87259-035-6
}}
</ref>

<ref name=Curt-1990-07>
{{cite magazine
 |first=Ronald J. |last=Curt
 |date=July 1990
 |title=In the blink of an eye
 |magazine=[[QST magazine]]
 |page=44
}}
</ref>

<ref name=Deutsch-Österreich-Telegr-1851>
{{cite report
 |title=[No title cited]
 |publisher=Deutsch-Österreichischer Telegraphenverein (German-Austrian Telegraph Union)
 |year=1851
 |lang=DE
 |quote=The Deutsch-Österreichischer Telegraphenverein officially adopted Gerke's redaction / revision of Morse code in 1851.
}}{{full citation needed|date=May 2021}}
</ref>

<ref name=dik-archive>
{{cite web
 |title=Morse  |series=Codes
 |website=homepages.cwi.nl/~dik  |language=en
 |url=http://homepages.cwi.nl/~dik/english/codes/morse.html
 |url-status=dead  |access-date=2021-05-19
 |archive-url=https://web.archive.org/web/20101109183046/http://homepages.cwi.nl/~dik/english/codes/morse.html
 |archive-date=2010-11-09
}}
</ref>

<ref name=Eckersley-1985>
{{cite book
 |editor-first=R.J. |editor-last=Eckersley
 |year=1985
 |title=Amateur Radio Operating Manual
 |publisher=[[Radio Society of Great Britain]]
 |isbn=0-900612-69-X
}}
</ref>

<ref name=Economist-1999-01-23>
{{cite magazine
 |title=An obituary for Morse code
 |date=23 January 1999
 |magazine=[[The Economist]]
 |url=https://www.economist.com/node/183572
 |archive-url=https://web.archive.org/web/20170330221624/https://www.economist.com/node/183572
 |archive-date=2017-03-30
}}
</ref>

<ref name=Everitt-1937>
{{cite book
 |first=W.L. |last=Everitt
 |year=1937
 |title=Communication Engineering
 |edition=2nd  |page=6
 |place=New York, NY
 |publisher=McGraw-Hill
 |url=https://archive.org/details/communicationeng00ever/page/n7/mode/2up
}}
</ref>

<ref name=FAA-2015-Air-Nav>
{{cite web
 |title=Chapter&nbsp;1. Air Navigation
 |work=faa.gov
 |date=3 January 2015
 |url=http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0101.html
 |access-date=January 21, 2015  |url-status=dead
 |archive-url=https://web.archive.org/web/20141201115959/http://www.faa.gov/air_traffic/publications/atpubs/aim/aim0101.html
 |archive-date=December 1, 2014
}}
</ref>

<ref name=FCC-AIM-ch-1>
{{cite book
 |chapter=Chapter&nbsp;1
 |title=Aeronautical Information Manual (AIM)
 |publisher=U.S. [[Federal Aviation Administration]]
 |chapter-url=http://www.faa.gov/air_traffic/publications/ATpubs/AIM/Chap1/aim0101.html
 |access-date=2007-12-10 |url-status=dead
 |archive-url=https://web.archive.org/web/20090904034127/http://www.faa.gov/air_traffic/publications/ATpubs/AIM/Chap1/aim0101.html
 |archive-date=September 4, 2009
}}
</ref>

<ref name=Fahie-1884>
{{cite book
 |last=Fahie |first=John Joseph
 |year=1884
 |title=A History of Electric Telegraphy, to the Year 1837
 |publisher=E. & F.N. Spon
 |url=https://www.princeton.edu/ssp/joseph-henry-project/telegraph/A_history_of_electric_telegraphy_to_the.pdf
 |access-date=21 November 2017  |url-status=live
 |archive-url=https://web.archive.org/web/20170715230109/http://www.princeton.edu/ssp/joseph-henry-project/telegraph/A_history_of_electric_telegraphy_to_the.pdf
 |archive-date=15 July 2017
}}
</ref>

<ref name=FCC-radiotelegraph>
{{cite web
 |title=Radiotelegraph Operator License (T)
 |website=fcc.gov
 |publisher=[[Federal Communications Commission]]
 |url=http://wireless.fcc.gov/commoperators/index.htm?job=tn
 |access-date=January 21, 2015 |url-status=live
 |archive-url=https://web.archive.org/web/20150113043918/http://wireless.fcc.gov/commoperators/index.htm?job=tn
 |archive-date=January 13, 2015
}}
</ref>

<ref name=Freebody-1959>
{{cite book
 |last=Freebody |first=J.W.
 |year=1959
 |chapter=Historical survey of telegraphy
 |title=Telegraphy
 |pages=28–29
 |place=London, UK
 |publisher=Sir Isaac Pitman & Sons, Ltd.
}}
</ref>

<ref name=Google-android-9011881>
{{cite web
 |title=Android accessibility help: Use Morse code
 |date=2018
 |website=Google support 
 |access-date=21 December 2018
 |url=https://support.google.com/accessibility/android/answer/9011881?co=GENIE.Platform%3DAndroid
}}
</ref>

<ref name=Guinness-records-Morse>
{{cite web
 |title=Fastest speed for a Morse code transmission
 |website=Guinnessworldrecords.com
 |url=http://www.guinnessworldrecords.com/world-records/fastest-speed-for-a-morse-code-transmission/
 |access-date=1 December 2017 |url-status=live
 |archive-url=https://web.archive.org/web/20170703145315/http://www.guinnessworldrecords.com/world-records/fastest-speed-for-a-morse-code-transmission/
 |archive-date=3 July 2017
}}
</ref>

<ref name=Howeth-1963>
{{cite book
 |first=Linwood S. |last=Howeth
 |year=1963
 |title=History of Communications-Electronics in the United States: Early Navy efforts to develop aircraft radio
 |publisher=For sale by the Superintendent of Documents, U. S. Govt. Print. Off.
 |url=https://babel.hathitrust.org/cgi/pt?id=mdp.39015002078809;view=1up;seq=221
}}
</ref>

<ref name=IARU-2003-07-03>
{{cite press release
 |title=rel 2003-07-03 att-2
 |publisher=The International Amateur Radio Union
 |website=IARU web (iaru.org)
 |url=http://www.iaru.org/rel030703att2.html
 |url-status=dead
 |archive-url=https://web.archive.org/web/20120906050331/http://www.iaru.org/rel030703att2.html
 |archive-date=September 6, 2012
}}
</ref>

<ref name=ITU-R-M-1172>
{{cite report
 |title=Miscellaneous abbreviations and signals to be used for radiocommunications in the maritime mobile service
 |series=ITU Recommendation
 |id=ITU-R M.1172
 |website=ITU.int
 |location=Geneva, CH
 |publisher=[[International Telecommunication Union]]
 |department=[[ITU-R|Radiocommunication Sector]]
 |url=https://www.itu.int/rec/R-REC-M.1172/en  |lang=en
}}
</ref>

<ref name=ITU-R-M-1677>
{{cite report
 |title=International Morse Code Recommendation
 |date=October 2009
 |series=ITU Recommendation
 |id=ITU-R M.1677-1
 |website=itu.int
 |publisher=[[International Telecommunication Union]]
 |department=[[ITU-R|Radiocommunication Sector]]
 |url=http://www.itu.int/rec/R-REC-M.1677-1-200910-I/
 |access-date=23 December 2011  |url-status=live
 |archive-url=https://web.archive.org/web/20121106142719/http://www.itu.int/rec/R-REC-M.1677-1-200910-I/
 |archive-date=6 November 2012
}}
</ref>

<ref name=K2TQN-blog>
{{cite web
 |title=K2TQN vintage radio column
 |website=K2tqn.com
 |type=blog
 |url=http://www.k2tqn.com/
 |access-date=1 December 2017 |url-status=live
 |archive-url=https://web.archive.org/web/20170911235907/http://k2tqn.com/
 |archive-date=11 September 2017
}}
</ref>

<ref name=Maritime-Radio-Hist-Soc-main>
{{cite web
 |title=Maritime Radio Historical Society
 |website=radiomarine.org
 |url=http://radiomarine.org/
 |access-date=1 December 2017 |url-status=live
 |archive-url=https://web.archive.org/web/20171009162131/http://www.radiomarine.org/
 |archive-date=9 October 2017
}}
</ref>

<ref name=Maritime-Radio-Hist-Soc-pab1_7>
{{cite web
 |title=Maritime Radio Historical Society
 |website=radiomarine.org
 |url=http://radiomarine.org/gallery/show?keyword=eom&panel=pab1_7#pab1_7undefined
 |access-date=1 December 2017  |url-status=live
 |archive-url=https://web.archive.org/web/20180125150630/http://radiomarine.org/gallery/show?keyword=eom&panel=pab1_7#pab1_7undefined
 |archive-date=25 January 2018
}}
</ref>

<ref name=Morsecode-NL-EHSC>
{{cite web
 |title=Extremely High Speed Club official web page
 |website=Morsecode.nl
 |url=http://www.morsecode.nl/ehsc%20club.html
 |access-date=1 December 2017  |url-status=live
 |archive-url=https://web.archive.org/web/20170628155518/http://morsecode.nl/ehsc%20club.html
 |archive-date=28 June 2017
}}
</ref>

<ref name=Navy-1957-RM32-10228B>
{{cite book
 |department=Bureau of Naval Personnel, U.S. Navy
 |year=1957
 |title=Radioman 3 & 2
 |id=RM32-10228B
 |place=Washington, DC
 |publisher=U.S. Government Printing Office
 |pages=105–111
 |url=http://www.navy-radio.com/manuals/rm32-10228B-1957.pdf
}}
</ref>

<ref name=Newell-Nabarro-1968>
{{cite journal |first1=A.F. |last1=Newell and |first2=C.D. |last2=Nabavi |title=VOTEM: the voice operated typewriter employing Morse code |journal=J. Phys. E: Sci. Instrum. |volume=2 |issue=8 |pages=655–657  |date=1969 |doi=10.1088/0022-3735/2/8/314 |pmid=5807885}}
</ref>

<ref name=OED-iddy-umpty>
{{cite dictionary
 |title=Iddy-umpty
 |dictionary=Oxford English Dictionary
 |url=http://www.oed.com/view/Entry/90951
 |access-date=22 October 2016  |url-access=subscription
}}
</ref>

<ref name=Perera-W1TP-Teleg-Mus>
{{cite web
 |last=Perera  |first=Tom
 |title=The "Morse" code and the continental code
 |website=W1TP Telegraph & Scientific Instruments Museums
 |url=http://w1tp.com/percode.htm
 |access-date=23 December 2011  |url-status=dead
 |archive-url=https://web.archive.org/web/20111209133401/http://w1tp.com/percode.htm
 |archive-date=9 December 2011
}}
</ref>

<ref name=Pierpont-N0HFF-2004>
{{cite book
 | last=Pierpont  | first=William G.
 | date=2004-05-13
 | orig-year=2002
 | title=The Art & Skill of Radio Telegraphy
 | url=http://www.pcpractice.com/CW/The%20Art%20&%20Skill%20of%20Radio%20Telegraphy%20-%203rd%20edition.pdf
 | access-date=2013-06-14
 | via=pcpractice.com
 | url-status=live
 | archive-url=https://web.archive.org/web/20120226193434/http://www.pcpractice.com/CW/The%20Art%20%26%20Skill%20of%20Radio%20Telegraphy%20-%203rd%20edition.pdf
 | archive-date=2012-02-26
}}
</ref>

<ref name=Pilotnav-sps-10404>
{{cite web
 |title=WG - Winnipeg
 |website=Pilotnav.com
 |url=http://www.pilotnav.com/navaid/sps-10404
 |access-date=1 December 2017  |url-status=live
 |archive-url=https://web.archive.org/web/20171202053301/http://www.pilotnav.com/navaid/sps-10404
 |archive-date=2 December 2017
}}
</ref>

<ref name=Pop-Sci-1918-04-Zeppelin>
{{cite magazine
 |title=How the Zeppelin raiders are guided by radio signals
 |date=April 1918
 |magazine=[[Popular Science Monthly]]
 |pages=632–634
 |url=https://babel.hathitrust.org/cgi/pt?id=uc1.a0005885587;view=1up;seq=652
 |access-date=March 4, 2018
}}
</ref>

<ref name=Preece-Sivewright-1891>
{{cite book
 |first1=W.H. |last1=Preece
 |first2=J.   |last2=Sivewright
 |year=1891
 |title=Telegraphy
 |page=40
 |place=London, UK
 |publisher=Longmans, Green, and Co.
 |url=https://archive.org/details/telegraphy07sivegoog/page/n56
}}
</ref>

<ref name=QSL-Prosigns>
{{cite web
 |title=Prosigns
 |publisher=QTH.Com
 |url=http://www.qsl.net/w8rit/prosigns.htm
 |access-date=January 21, 2015  |url-status=live
 |via=QSL.net
 |archive-url=https://web.archive.org/web/20150924105824/http://www.qsl.net/w8rit/prosigns.htm
 |archive-date=September 24, 2015
}}
</ref>

<ref name=Quadibloc-pp1323>
{{cite web
 |title=Fractionated Morse, and other oddities
 |series=Crypto
 |website=Quadibloc.com
 |url=http://www.quadibloc.com/crypto/pp1323.htm
 |access-date=2013-11-21
}}
</ref>

<ref name=Radio-mag-Handbook-1940>
{{cite book
 |editor1-first=W.W.   |editor1-last=Smith
 |editor2-first=Ray L. |editor2-last=Dawley
 |editor3-first=E.H.   |editor3-last=Conklin
 |collaboration=Editors of ''Radio'' magazine
 |display-editors=2
 |year=1940 
 |title=The "Radio" Handbook
 |page=178
 |edition=7th
 |place=Santa Barbara, CA
 |publisher=Editors and Engineers Ltd.
 |url=https://archive.org/details/The_Radio_Handbook_7th_Edition_1948/page/178/mode/1up?view=theater
 |access-date=2022-07-18
}}
</ref>

<ref name=Reverse-Beacon>
{{cite web
 |title=Welcome! - Reverse Beacon Network
 |website=Reversebeacon.net
 |url=http://www.reversebeacon.net/
 |access-date=1 December 2017  |url-status=live
 |archive-url=https://web.archive.org/web/20170912071400/http://reversebeacon.net/
 |archive-date=12 September 2017
}}
</ref>

<ref name=Ross-1992-03>
{{cite magazine
 |first=Dennis W. |last=Ross
 |date=March 1992
 |title=Morse code: A place in the mind
 |magazine=[[QST magazine]]
 |page=51
}}
</ref>

<ref name=Smithsonian-Report-1879>
{{cite report
 |title=Annual Report of the Board of Regents of the Smithsonian Institution for the Year 1878
 |year=1879
 |pages=358–360
 |place=Washington, DC
 |publisher=Smithsonian Institution
 |via=Archive.org
 |url=https://archive.org/details/annualreportofbo1878smit/page/358/mode/2up
 |access-date=2021-03-17
}}
</ref>

<ref name=Stanley-2000>
{{cite book
 |first=Glenn |last=Stanley
 |series=[[Cambridge Companions to Music]]
 |title=The Cambridge Companion to Beethoven
 |page=269
 |place=Cambridge, UK
 |publisher=Cambridge University Press
 |year=2000
 |isbn=0-521-58934-7
}}
</ref>

<ref name=Studwell-1997>
{{cite book
 |first=William Emmett |last=Studwell
 |year=1997
 |title=The Americana Song Reader
 |page=62
 |publisher=Routledge
 |isbn=0-7890-0150-0
}}
</ref>

<ref name=Swling-2015-12-10>
{{cite web
 |title=Morse code training in the Air Force
 |date=10 December 2015
 |website=Swling.com
 |url=http://swling.com/blog/2015/12/morse-code-training-in-the-air-force/
 |access-date=1 December 2017 |url-status=live
 |archive-url=https://web.archive.org/web/20170702064540/http://swling.com/blog/2015/12/morse-code-training-in-the-air-force/
 |archive-date=2 July 2017
}}
</ref>

<ref name=UK-Engr-1919-1938>
{{cite report
 |author=Engineer-in-Chief's Office
 |orig-year=1919 |year=1938
 |title=Elementary Principles of Telegraphy and Systems up to Morse Duplex
 |page=6
 |series=Technical Pamphlets for Workmen
 |place=London, UK
 |publisher=His Majesty's Stationery Office
}}
</ref>

<ref name=USCG-2011-Circ-1367-Amd>
{{cite web
 |title=Amendments to the International Aeronautical and Maritime Search and Rescue (IAMSAR) Manual
 |id=Circ&nbsp;1367, Amd
 |year=2011
 |website=USCG.mil
 |url=http://www.uscg.mil/hq/cg5/cg534/nsarc/MSC.1%20Circ%201367%20Amd%202011.pdf
 |access-date=1 December 2017
}}
</ref>

<ref name=US-CFR-Title-47>
United States Code of Federal Regulations
Title&nbsp;47 
§13.207(c), §13.209(d), §97.503&nbsp;[1996]
</ref>

<ref name=War-1943-TM-11-459>
{{cite book
 |publisher=War Department
 |year=1943
 |title=Instructions for Learning International Morse Characters
 |id=TM 11-459
 |pages=52, 68–72
 |url=https://archive.org/details/Tm11-459_676-nsia/page/n67
}}
</ref>

<ref name=Winmorse-custom-Farnsw>
{{cite web
 |title=Custom Farnsworth spacing configuration
 |publisher=Winmorse.com
 |url=http://www.winmorse.com/Documentation/Custom%20Farnsworth%20Spacing.htm
 |access-date=2013-11-21  |url-status=live
 |archive-url=https://web.archive.org/web/20160304044041/http://www.winmorse.com/Documentation/Custom%20Farnsworth%20Spacing.htm
 |archive-date=2016-03-04
}}
</ref>

<ref name=Wythoff-2014>
{{cite periodical
 |last=Wythoff |first=Grant
 |date=July 2014
 |title=The Invention of Wireless Cryptography
 |periodical=The Appendix: Futures of the Past
 |volume=2 |issue=3
 |url=http://theappendix.net/issues/2014/7/the-invention-of-wireless-cryptography
 |access-date=2015-01-28  |url-status=live
 |archive-url=https://web.archive.org/web/20141208040245/http://theappendix.net/issues/2014/7/the-invention-of-wireless-cryptography
 |archive-date=2014-12-08
}}
</ref>

<ref name=Ziegenhain-2013>
{{cite web
 |first=Gerolf  |last=Ziegenhain
 |date=2013-05-20
 |title=Morse decoder test – iPhone / iPad
 |website=Gerolfziegenhain.wordpress.com
 |url=http://gerolfziegenhain.wordpress.com/2013/05/20/morse-decoder-test-iphone-ipad/
 |access-date=2016-09-17 |url-status=live
 |archive-url=https://web.archive.org/web/20170727175641/https://gerolfziegenhain.wordpress.com/2013/05/20/morse-decoder-test-iphone-ipad/
 |archive-date=2017-07-27
}}
</ref>

}} <!-- End of "refs=" -->

==External links==
{{Commons|Morse code|Morse code}}

*{{cite encyclopedia
 |url=https://www.britannica.com/topic/Morse-Code
 |encyclopedia=Encyclopædia Britannica
 |title=Morse code
|date=16 October 2023
 }}

* {{cite web
 |title=Morse code
 |department=Radio Amateur
 |series=Recreation
 |website=[[Curlie]].org
 |url=https://curlie.org/Recreation/Radio/Amateur/Morse_Code/
}}

* {{cite web
 |title=Morse Code resources
 |website=DXZone.com
 |url=http://www.dxzone.com/catalog/Operating_Modes/Morse_code/
}}

* {{cite web
 |title=Morse code MP3 practice files
 |website=starling.us
 |url=http://starling.us/free/morse
}} — 200&nbsp;hours of at increasing speeds plus an ASCII-to-CW file generator program.

* {{cite AV media
 |title= International Morse code, hand sending
 |year=1966
 |publisher=[[United States Army|U.S. Army]]
 |medium=training film
 |website=YouTube
 |url=https://www.youtube.com/watch?v=R-petiNdCIY
}} Archived at [https://ghostarchive.org/varchive/youtube/20211211/R-petiNdCIY Ghostarchive]{{cbignore}} and the [https://web.archive.org/web/20120707064749/https://www.youtube.com/watch?v=R-petiNdCIY Wayback Machine]{{cbignore}}:

* {{cite AV media
 |title=Technique of hand sending
 |year=1944
 |series=Morse code radio operator training
 |publisher=[[United States Navy|U.S. Navy]]
 |medium=training film
 |website=YouTube
 |url=https://www.youtube.com/watch?v=iC5RQNSSZH0 
| archive-url=https://web.archive.org/web/20120707064836/https://www.youtube.com/watch?v=iC5RQNSSZH0| archive-date=2012-07-07 | url-status=dead}}

* {{cite web
 |title=Codes of the World
 |website=nonstopsystems.com
 |url=http://www.nonstopsystems.com/radio/pdf-hell/article-hell-codw-sowp.pdf
}}

{{Morse code}}
{{Telecommunications}}
{{character encoding}}
{{list of writing systems}}
{{Authority control}}

{{DEFAULTSORT:Morse Code}}
[[Category:Morse code| ]]
[[Category:American inventions]]
[[Category:Latin-script representations]]
[[Category:1848 introductions]]
[[Category:Scoutcraft]]
[[Category:Amateur radio]]