Editing Morse code (section)

==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}}

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===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 [[letter frequency]] of English by counting the [[movable type]] he found in the [[Type case|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}}'''. The codes for the digits '''0'''–'''9''' in International Morse were completely revised from both Morse's original and Gerke's revised systems. 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/>