Morse code

Morse code

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Transmission of language with brief pulses

Chart of the Morse code 26 letters and 10 numerals.^[1]

Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called dots and dashes or dits and dahs.^[2][3] Morse code is named for Samuel F. B. Morse, an inventor of the telegraph.

The International Morse Code encodes the 26 English letters A through Z, some non-English letters, the Arabic numerals and a small set of punctuation and procedural signals (prosigns). There is no distinction between upper and lower case letters.^[1] Each Morse code symbol is formed by a sequence of dots and dashes. The dot duration is the basic unit of time measurement in Morse code transmission. The duration of a dash is three times the duration of a dot. Each dot or dash within a character is followed by period of signal absence, called a space, equal to the dot duration. The letters of a word are separated by a space of duration equal to three dots, and the words are separated by a space equal to seven dots.^[1] To increase the efficiency of encoding, Morse code was designed so that the length of each symbol is approximately inverse to the frequency of occurrence in text of the English language character that it represents. Thus the most common letter in English, the letter "E", has the shortest code: a single dot. 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. The Morse code transmission rate (speed) is specified in groups per minute, commonly referred to as words per minute.^[4]

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.^[5][6] The current or wave is present during the time period of the dot or dash and absent during the time between dots and dashes.^[7][8]

Morse code can be memorized, and Morse code signalling in a form perceptible to the human senses, such as sound waves or visible light, can be directly interpreted by persons trained in the skill.^[9][10]

Because many non-English natural languages use other than the 26 Roman letters, Morse alphabets have been developed for those languages.^[11]

SOS, the standard emergency signal, is a Morse code prosign

In an emergency, Morse code can be generated by improvised methods such as turning a light on and off, tapping on an object or sounding a horn or whistle, making it one of the simplest and most versatile methods of telecommunication. The most common distress signal is SOS – three dots, three dashes, and three dots – internationally recognized by treaty.

Contents

• 1Development and history
• 2User proficiency
• 3International Morse Code
  • 3.1Aviation
  • 3.2Amateur radio
  • 3.3Other uses
  • 3.4Applications for the general public
  • 3.5Morse code as an assistive technology
• 4Representation, timing, and speeds
  • 4.1Transmission
  • 4.2Cable code
  • 4.3Timing
  • 4.4Spoken representation
  • 4.5Speed in words per minute
  • 4.6Farnsworth speed
  • 4.7Alternative display of common characters in International Morse code
  • 4.8Link budget issues
• 5Learning methods
  • 5.1Mnemonics
• 6Letters, numbers, punctuation, prosigns for Morse code and non-English variants
  • 6.1Prosigns
  • 6.2Symbol representations
  • 6.3Non-Latin extensions
  • 6.4Unusual variants
• 7Decoding software
• 8See also
• 9References
• 10Bibliography
• 11External links

Development and history

Single needle telegraph instrument

Telegraph key and sounder. The signal is on" when the knob is pressed, and "off" when it is released. Length and timing of the dots and dashes are entirely controlled by the telegraphist.

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 piles producing electrochemical and electromagnetic changes. These numerous ingenious experimental designs were precursors to practical telegraphic applications.^[12]

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 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 dot and a deflection to the right to a dash.^[13] By making the two clicks sound different with one ivory and one metal stop, the single needle device became an audible instrument, which led in turn to the Double Plate Sounder System.^[14]

Morse code receiver, recording on paper tape

The American artist Samuel F. B. Morse, the American physicist Joseph Henry, and Alfred Vail developed an electrical telegraph system. It needed a method to transmit natural language using only electrical pulses and the silence between them. Around 1837, Morse, therefore, developed an early forerunner to the modern International Morse code. William Cooke and Charles Wheatstone in Britain developed an electrical telegraph that used electromagnets in its receivers. They obtained an English patent in June 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 telegraphs. In 1841, Cooke and Wheatstone built a telegraph that printed the letters from a wheel of typefaces struck by a hammer.^[15]

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 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.^[16] The shorter marks were called "dots" and the longer ones "dashes", and the letters most commonly used were assigned the shorter sequences of dots and dashes. This code was used since 1844 and became known as Morse landline code or American Morse code.

Comparison of historical versions of Morse code with the current standard. 1. American Morse code as originally defined. 2. The modified and rationalized version used by Gerke on German railways. 3. The current ITU standard.

In the original Morse telegraphs, the receiver's armature made a clicking noise as it moved in and out of position to mark the paper tape. The 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. It was later found that people become more proficient at receiving Morse code when it is taught as a language that is heard, instead of one read from a page.^[17]

To reflect the sounds of Morse code receivers, the operators began to vocalize a dot as "dit", and a dash as "dah". Dots which are not the final element of a character became vocalized as "di". For example, the letter "c" was then vocalized as "dah-di-dah-dit".^[18][19] Morse code was sometimes facetiously known as "iddy-umpty" and a dash as "umpty", leading to the word "umpteen".^[20]

The Morse code, as it is used internationally today, was derived from a much refined proposal by Friedrich Clemens Gerke in 1848 that became known as the "Hamburg alphabet". Gerke changed many of the codepoints, in the process doing away with the different length dashes and different inter-element spaces of American Morse, leaving only two coding elements, the dot and the dash. Codes for German umlauted vowels and "ch" were introduced. Gerke's code was adopted by the Deutsch-Österreichischer Telegraphenverein (German-Austrian Telegraph Society) in 1851. This finally led to the International Morse code in 1865. The International Morse code adopted most of Gerke's codepoints. The codepoints for "O" and "P" were taken from Steinheil's code. A new codepoint was added for "J" since Gerke did not distinguish between "I" and "J". Changes were also made to "Q", "X", "Y", "Z". This left only four codepoints identical to the original Morse code, namely "E", "H", "K" and "N", and the latter two have had their dashes lengthened. The original code being compared dates to 1838, not the code shown in the table which was developed in the 1840s.^[21]

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 centuries, most high-speed international communication used Morse code on telegraph lines, undersea cables and radio circuits. In aviation, Morse code in radio systems started to be used on a regular basis in the 1920s. Although previous transmitters were bulky and the spark gap system of transmission was difficult to use, there had been some earlier attempts. In 1910, the US Navy experimented with sending Morse from an airplane.^[22] That same year, a radio on the airship America had been instrumental in coordinating the rescue of its crew.^[23] Zeppelin airships equipped with radio were used for bombing and naval scouting during World War I,^[24] and ground-based radio direction finders were used for airship navigation.^[24] 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 to Paris in 1927. once he and the Spirit of St. Louis were off the ground, Lindbergh was truly alone and incommunicado. on the other hand, when the first airplane flight was made from California to Australia in 1928 on the Southern Cross, one of its four crewmen was its radio operator who communicated with ground stations via 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 which transmitted continuous two- or three-letter identifiers in Morse code. Aeronautical charts show the identifier of each navigational aid next to its location on the map.

Radiotelegraphy using Morse code was vital during World War II, especially in carrying messages between the warships and the naval bases 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 warplanes, especially by long-range patrol planes that were sent out by those navies to scout for enemy warships, cargo ships, and troop ships.

In addition, rapidly moving armies in the field could not have fought effectively without radiotelegraphy because they moved more rapidly than telegraph and telephone lines could be erected. 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.

A U.S. Navy Morse Code training class in 2015. The sailors will use their new skills to collect signals intelligence.

Morse code was used as an international standard for maritime distress until 1999 when it was replaced by the Global Maritime Distress 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 cry before our eternal silence."^[25] In the United States the final commercial Morse code transmission was on July 12, 1999, signing off with Samuel Morse's original 1844 message, "What hath God wrought", and the prosign "SK".^[26]

As of 2015, the United States Air Force still trains ten people a year in Morse.^[27] 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 500 kHz.^[28] However, the Federal Communications Commission still grants commercial radiotelegraph operator licenses to applicants who pass its code and written tests.^[29] Licensees have reactivated the old California coastal Morse station KPH and regularly transmit from the site under either this Call sign or as KSM. Similarly, a few US Museum ship stations are operated by Morse enthusiasts.^[30]

User proficiency

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. Manipulation of dual-lever paddles is similar to the Vibroplex, but pressing the right paddle generates a series of dahs, and squeezing the paddles produces dit-dah-dit-dah sequence. The actions are reversed for left-handed operators.

Morse code speed is measured in words per minute (wpm) or characters per minute (cpm). Characters have differing lengths because they contain differing numbers of dots and dashes. Consequently, words also have different lengths in terms of dot duration, even when they contain the same number of characters. For this reason, a standard word is helpful to measure operator transmission speed. "PARIS" and "CODEX" are two such standard words.^[31] Operators skilled in Morse code can often understand ("copy") code in their heads at rates in excess of 40 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 1939 at a contest in Asheville, North Carolina in the United States Ted R. McElroy W1JYN set a still-standing record for Morse copying, 75.2 wpm.^[32] William Pierpont N0HFF also notes that some operators may have passed 100 wpm.^[32] 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 W9YZE (d. 1992) who reached 35 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 dot durations versus 60 dot durations) and different interword gaps (5 dot durations versus 7 dot durations) may have been used when determining such speed records. For example, speeds run with the CODEX standard word and the 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 wpm.^[33] Also, Certificates of Code Proficiency are issued by several amateur radio societies, including the American Radio Relay League. Their basic award starts at 10 wpm with endorsements as high as 40 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 wpm.

International Morse Code

Morse code has been in use for more than 160 years—longer than any other electrical coding 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 numerals, providing the foundation for the modern form of the code. After some minor changes, International Morse Code was standardized at the International Telegraphy Congress in 1865 in Paris and was later made the standard by the International Telecommunication Union (ITU). Morse's original code specification, largely limited to use in the United States and Canada, became known as American Morse code or railroad code. American Morse code is now seldom used except in historical re-enactments.

Aviation

Cayo Largo Del Sur VOR-DME.

In aviation, pilots use radio navigation aids. To ensure that the stations the pilots are using 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 VOR-DME based at Vilo Acuña Airport in Cayo Largo del Sur, Cuba is coded as "UCL", and UCL in Morse code is transmitted on its radio frequency. In some countries, during periods of maintenance, the facility may radiate a T-E-S-T code (▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄) or the code may be removed which tells pilots and navigators that the station is unreliable. In Canada, the identification is removed entirely to signify the navigation aid is not to be used.^[34][35] In the aviation service, Morse is typically sent at a very slow speed of about 5 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.

Menu

0:00

The sound of non directional beacon WG, on 248 kHz, located at 49.8992 North, 97.349197 West,^[36] near Winnipeg's main airport

Amateur radio

Vibroplex brand semiautomatic key (generically called a "bug"). The paddle, when pressed to the right by the thumb, generates a series of dits, the length and timing of which are controlled by a sliding weight toward the rear of the unit. When pressed to the left by the knuckle of the index finger, the paddle generates a single dah, the length of which is controlled by the operator. Multiple dahs require multiple presses. Left-handed operators use a key built as a mirror image of this one.

International Morse code today is most popular among amateur radio operators, in the mode commonly referred to as "continuous wave" or "CW". (This name was chosen to distinguish it from the damped wave emissions from spark transmitters, not because the transmission is continuous.) Other keying methods are available in radio telegraphy, such as frequency shift keying.

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.^[37] Many countries subsequently removed the Morse requirement from their licence requirements.^[38]

Until 1991, a demonstration of the ability to send and receive Morse code at a minimum of five words per minute (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 HF bands. Until 2000, proficiency at the 20 wpm level was required to receive the highest level of amateur license (Amateur Extra Class); effective April 15, 2000, the FCC reduced the Extra Class requirement to five wpm.^[39] 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—LF, MF, HF, VHF, and UHF. In some countries, certain portions of the amateur radio bands are reserved for transmission of Morse code signals only.

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 codes, and a set of Morse code abbreviations for typical message components. For example, CQ is broadcast to be interpreted as "seek you" (I'd like to converse with anyone who can hear my signal). OM (old man), YL (young lady) and XYL ("ex-YL" – wife) are common abbreviations. YL or OM is used by an operator when referring to the other operator, XYL or OM is used by an operator when referring to his or her spouse. QTH is "location" ("My QTH" 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 keyers (known as "bugs") and of fully automatic electronic keyers is prevalent today. Software is also frequently employed to produce and decode Morse code radio signals.

Many amateur radio repeaters identify with Morse, even though they are used for voice communications.

Other uses

A U.S. Navy signalman sends Morse code signals in 2005.

Through May 2013, the First, Second, and Third Class (commercial) Radiotelegraph Licenses using code tests based upon the CODEX standard word were still being issued in the United States by the Federal Communications Commission. The First Class license required 20 WPM code group and 25 WPM text code proficiency, the others 16 WPM code group test (five letter blocks sent as simulation of receiving encrypted text) and 20 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 WPM codegroup and 20 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 WPM test requirement.

Radio navigation aids such as VORs and NDBs for aeronautical use broadcast identifying information in the form of Morse Code, though many VOR stations now also provide voice identification.^[40] Warships, including those of the U.S. Navy, have long used signal lamps to exchange messages in Morse code. Modern use continues, in part, as a way to communicate while maintaining radio silence.

ATIS (Automatic Transmitter Identification System) uses Morse code to identify uplink sources of analog satellite transmissions.

Applications for the general public

Representation of SOS-Morse code.

An important application is signalling for help through SOS, "▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄". This can be sent many ways: keying a radio on and off, flashing a mirror, toggling a flashlight, and similar methods. SOS is not three separate characters, rather, it is a prosign SOS, and is keyed without gaps between characters.^[41]

Some Nokia mobile phones offer an option to alert the user of an incoming text message with the Morse tone "▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄" (representing SMS or Short Message Service).^[42] In addition, applications are now available for mobile phones that enable short messages to be input in Morse Code.^[43]

Morse code as an assistive technology

Morse code has been employed as an assistive technology, helping people with a variety of disabilities to communicate. For example, the Android operating system versions 5.0 and higher allow users to input text using Morse Code as an alternative to a keypad or handwriting recognition.^[44]

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, Newell and 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 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,^[45] 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,^[46][47] Another example occurred in 1966 when prisoner of war Jeremiah Denton, brought on television by his North Vietnamese captors, Morse-blinked the word TORTURE. In these two cases, interpreters were available to understand those series of eye-blinks.

Representation, timing, and speeds

	A sample Morse code transmission Menu 0:00 The text "Welcome to Wikipedia, the free encyclopedia that anyone can edit." sent as Morse code at 13 wpm.
Problems playing this file? See media help.

	Morse code A through Z Menu 0:00 "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 wpm.
Problems playing this file? See media help.

This section includes inline links to audio files. If you have trouble playing the files, see Wikipedia Media help.

International Morse code is composed of five elements:^[1]

1. short mark, dot or "dit" (▄▄▄▄): "dot duration" is one time unit long
2. longer mark, dash or "dah" (▄▄▄▄▄▄): three time units long
3. inter-element gap between the dots and dashes within a character: one dot duration or one unit long
4. short gap (between letters): three time units long
5. medium gap (between words): seven time units long

Transmission

Morse code can be transmitted in a number of ways: originally as electrical pulses along a telegraph wire, but also as an audio tone, a radio signal with short and long 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 dash.

Morse code is transmitted using just two states (on and off). Historians have called it the first digital code. 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 made from a combination of the following five bit-strings:

1. short mark, dot or "dit" (▄▄▄▄): 1
2. longer mark, dash or "dah" (▄▄▄▄▄▄): 111
3. intra-character gap (between the dots and dashes within a character): 0
4. short gap (between letters): 000
5. medium gap (between words): 0000000

Note that the marks and gaps alternate: dots and dashes are always separated by one of the gaps, and that the gaps are always separated by a dot or a dash.

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 dashes 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.

Cable code

The very long time constants of 19th and early 20th century submarine communications cables 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.^[48]

Timing

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

−− −−− ·−· ··· ·       −·−· −−− −·· ·
M   O   R   S  E        C    O   D  E

Next is the exact conventional timing for this phrase, with = representing "signal on", and . representing "signal off", each for the time length of exactly one dit:

         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

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:

M   O   R   S  E          C    O   D  E
−− −−− ·−· ··· · (space) −·−· −−− −·· ·

is orally:

Dah-dah dah-dah-dah di-dah-dit di-di-dit dit, Dah-di-dah-dit dah-dah-dah dah-di-dit dit.

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 length. A dash is the length of 3 dots, and spacings are specified in number of dot lengths. An unambiguous method of specifying the transmission speed is to specify the dot duration as, for example, 50 milliseconds.

Specifying the dot 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 dot lengths. It is not immediately clear how a specific word rate determines the dot duration in milliseconds.

Some method to standardize the transformation of a word rate to a dot duration is useful. A simple way to do this is to choose a dot 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 words per minute, the operator would choose a dot rate that would send the typical word 13 times in exactly one minute.

The typical word thus determines the dot length. It is common to assume that a word is 5 characters long. There are two common typical words: "PARIS" and "CODEX". 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 "e" and "t". CODEX offers a word rate that is typical of 5-letter code groups (sequences of random letters). Using the word PARIS as a standard, the number of dot units is 50 and a simple calculation shows that the dot length at 20 words per minute is 60 milliseconds. Using the word CODEX with 60 dot units, the dot length at 20 words per minute is 50 milliseconds.

Because Morse code is usually sent by hand, it is unlikely that an operator could be that precise with the dot 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.^[49] The Commission specifies that a word is 5 characters long. The Commission specifies Morse code test elements at 16 code groups per minute, 20 words per minute, 20 code groups per minute, and 25 words per minute.^[50] The word per minute rate would be close to the PARIS standard, and the code groups per minute would be close to the 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.^[51]

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 word per minute plain text test and a 16 word per minute code group test.^[29]

Based upon a 50 dot duration standard word such as PARIS, the time for one dot duration or one unit can be computed by the formula:

T = 1200 / W

Where: T is the unit time, or dot duration in milliseconds, and W is the speed in wpm.

High-speed telegraphy contests are held; according to the Guinness Book of Records in June 2005 at the International Amateur Radio Union's 6th World Championship in High Speed Telegraphy in Primorsko, Bulgaria, Andrei Bindasov of Belarus transmitted 230 morse code marks of mixed text in one minute.^[52]

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 words per minute.

Using different character and text speeds is, in fact, a common practice, and is used in the Farnsworth method of 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.

Graphical representation of the dichotomic search table. The graph branches left for each dot and right for each dash until the character representation is exhausted.

Link budget issues

Morse Code cannot be treated as a classical radioteletype (RTTY) signal when it comes to calculating a link margin or a link budget for the simple reason of it possessing variable length dots and dashes as well as variant timing between letters and words. For the purposes of Information Theory and Channel Coding comparisons, the word PARIS is used to determine Morse Code's properties because it has an even number of dots and dashes.

Morse Code, when transmitted essentially, creates an AM signal (even in on/off keying mode), assumptions about signal can be made with respect to similarly timed RTTY signalling. Because Morse code transmissions employ an on-off keyed radio signal, it requires less complex transmission equipment than other forms of radio communication.

Morse code also requires less signal bandwidth than voice communication, typically 100–150 Hz, compared to the roughly 2400 Hz used by single-sideband voice, although at a lower data rate.

Morse code is usually heard at the receiver as a medium-pitched on/off audio tone (600–1000 Hz), 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 transmitted power is concentrated into a limited bandwidth so narrow receiver filters can be used to suppress interference from adjacent frequencies. The audio tone is usually created by use of a beat frequency oscillator.

The narrow signal bandwidth also takes advantage of the natural aural selectivity of the human brain, further enhancing weak signal readability. This efficiency makes CW extremely useful for DX (distance) transmissions, as well as for low-power transmissions (commonly called "QRP operation", from the Q-code for "reduce power").

The ARRL has a readability standard for robot encoders called ARRL Farnsworth Spacing^[53] that is supposed to have higher readability for both robot and human decoders. Some programs like WinMorse^[54] have implemented the standard.

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 dots, dashes, 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, named after German psychologist Ludwig Koch, 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.^{[citation needed]}

Mnemonics

Main article: Morse code mnemonics

Scout movement founder Baden-Powell's mnemonic chart from 1918

Visual mnemonic charts have been devised over the ages. Baden-Powell included one in the Girl Guides handbook^[55] 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, "Q" in Morse is dah-dah-di-dah, which can be memorized by the phrase "God save the Queen", and the Morse for "F" is di-di-dah-dit, which can be memorized as "Did she like it."

A well-known Morse code rhythm from the Second World War period derives from Beethoven's 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 "V", di-di-di-dah, understood as "V for Victory" (as well as the Roman numeral for the number five).^[56][57]

Letters, numbers, punctuation, prosigns for Morse code and non-English variants

Category	Character	Code
Letters	A, a	· − Menu 0:00
Letters	B, b	− · · ·  Menu 0:00
Letters	C, c	− · − ·  Menu 0:00
Letters	D, d	− · ·  Menu 0:00
Letters	E, e	·  Menu 0:00
Letters	F, f	· · − ·  Menu 0:00
Letters	G, g	− − ·  Menu 0:00
Letters	H, h	· · · ·  Menu 0:00
Letters	I, i	· ·  Menu 0:00
Letters	J, j	· − − −  Menu 0:00
Letters	K, k Prosign for "Invitation to transmit"	− · −  Menu 0:00
Letters	L, l	· − · ·  Menu 0:00
Letters	M, m	− −  Menu 0:00
Letters	N, n	− ·  Menu 0:00
Letters	O, o	− − −  Menu 0:00
Letters	P, p	· − − ·  Menu 0:00
Letters	Q, q	− − · −  Menu 0:00
Letters	R, r	· − ·  Menu 0:00
Letters	S, s	· · ·  Menu 0:00
Letters	T, t	−  Menu 0:00
Letters	U, u	· · −  Menu 0:00
Letters	V, v	· · · −  Menu 0:00
Letters	W, w	· − −  Menu 0:00
Letters	X, x	− · · −  Menu 0:00
Letters	Y, y	− · − −  Menu 0:00
Letters	Z, z	− − · ·  Menu 0:00
Numbers	0	− − − − −  Menu 0:00
Numbers	1	· − − − −  Menu 0:00
Numbers	2	· · − − −  Menu 0:00
Numbers	3	· · · − −  Menu 0:00
Numbers	4	· · · · −  Menu 0:00
Numbers	5	· · · · ·  Menu 0:00
Numbers	6	− · · · ·  Menu 0:00
Numbers	7	− − · · ·  Menu 0:00
Numbers	8	− − − · ·  Menu 0:00
Numbers	9	− − − − ·  Menu 0:00
Punctuation	Period [.]	· − · − · −  Menu 0:00
Punctuation	Comma [,]	− − · · − −  Menu 0:00
Punctuation	Question Mark [?]	· · − − · ·  Menu 0:00
Punctuation	Apostrophe [']	· − − − − ·  Menu 0:00
Punctuation	Exclamation Point [!] KW digraph Not in ITU-R recommendation	− · − · − −  Menu 0:00
Punctuation	Slash/Fraction Bar [/]	− · · − ·  Menu 0:00
Punctuation	Parenthesis (Open)	− · − − ·  Menu 0:00
Punctuation	Parenthesis (Close)	− · − − · −  Menu 0:00
Punctuation	Ampersand (or "Wait") [&] AS digraph Prosign for "WAIT"	· − · · ·  Menu 0:00
Punctuation	Colon [:]	− − − · · ·  Menu 0:00
Punctuation	Semicolon [;] Not in ITU-R ITU-R M.1172 or ITU-R M.1677-1	− · − · − ·  Menu 0:00
Punctuation	Double Dash [=]	− · · · −  Menu 0:00
Punctuation	Plus sign [+]	· − · − ·  Menu 0:00
Punctuation	Hyphen, Minus Sign [-]	− · · · · −  Menu 0:00
Punctuation	Underscore [_] Not in ITU-R ITU-R M.1172 or ITU-R M.1677-1	· · − − · −  Menu 0:00
Punctuation	Quotation mark ["]	· − · · − ·  Menu 0:00
Punctuation	Dollar sign [$] SX digraph Not in ITU-R ITU-R M.1172 or ITU-R M.1677-1	· · · − · · −  Menu 0:00
Punctuation	At Sign [@] AC digraph	· − − · − ·  Menu 0:00
Prosigns	End of work	· · · − · −  Menu 0:00
Prosigns	Error	· · · · · · · ·  Menu 0:00
Prosigns	Invitation to Transmit Also used for K	− · −  Menu 0:00
Prosigns	Starting Signal	− · − · −  Menu 0:00
Prosigns	New Page Signal AR digraph Message separator Single-line display may use printed "+"	· − · − ·  Menu 0:00
Prosigns	Understood Also used for Ŝ	· · · − ·  Menu 0:00
Prosigns	Wait also used for Ampersand [&]	· − · · ·  Menu 0:00
Non-English extensions	À, à Shared by À, Å	· − − · −  Menu 0:00
Non-English extensions	Ä, ä Shared by Ä, Æ, Ą	· − · −  Menu 0:00
Non-English Extensions	Å, å Shared by À, Å	· − − · −  Menu 0:00
Non-English extensions	Ą, ą Shared by Ä, Æ, Ą	· − · −  Menu 0:00
Non-English extensions	Æ, æ Shared by Ä, Æ, Ą	· − · −  Menu 0:00
Non-English extensions	Ć, ć Shared by Ć, Ĉ, Ç	− · − · · Menu 0:00
Non-English extensions	Ĉ, ĉ Shared by Ć, Ĉ, Ç	− · − · ·  Menu 0:00
Non-English Extensions	Ç, ç Shared by Ć, Ĉ, Ç	− · − · ·  Menu 0:00
Non-English extensions	CH, ch Shared by CH, Ĥ, Š	− − − −  Menu 0:00
Non-English extensions	Đ, đ Shared by Đ, É, Ę Not to be confused with Eth (Ð, ð) (É is the only accented character included in ITU-R recommendation)	· · − · ·  Menu 0:00
Non-English extensions	Ð, ð Not to be confused with D with stroke (Đ, đ)	· · − − ·  Menu 0:00
Non-English extensions	É, é Shared by Đ, É, Ę (É is the only accented character included in ITU-R recommendation)	· · − · ·  Menu 0:00
Non-English extensions	È, è Shared by È, Ł	· − · · −  Menu 0:00
Non-English extensions	Ę, ę Shared by Đ, É, Ę (É is the only accented character included in ITU-R recommendation)	· · − · ·  Menu 0:00
Non-English extensions	Ĝ, ĝ	− − · − ·  Menu 0:00
Non-English extensions	Ĥ, ĥ Shared by CH, Ĥ, Š	− − − −  Menu 0:00
Non-English extensions	Ĵ, ĵ	· − − − ·  Menu 0:00
Non-English extensions	Ł, ł Shared by È, Ł	· − · · −  Menu 0:00
Non-English extensions	Ń, ń Shared by Ń, Ñ	− − · − −  Menu 0:00
Non-English extensions	Ñ, ñ Shared by Ń, Ñ	− − · − −  Menu 0:00
Non-English extensions	Ó, ó Shared by Ó, Ö, Ø	− − − ·  Menu 0:00
Non-English extensions	Ö, ö Shared by Ó, Ö, Ø	− − − · Menu 0:00
Non-English extensions	Ø, ø Shared by Ó, Ö, Ø	− − − · Menu 0:00
Non-English extensions	Ś, ś	· · · − · · · Menu 0:00
Non-English extensions	Ŝ, ŝ Prosign for "Understood"	· · · − · Menu 0:00
Non-English extensions	Š, š Shared by CH, Ĥ, Š	− − − − Menu 0:00
Non-English extensions	Þ, þ	· − − · · Menu 0:00
Non-English extensions	Ü, ü Shared by Ü, Ŭ	· · − − Menu 0:00
Non-English extensions	Ŭ, ŭ Shared by Ü, Ŭ	· · − − Menu 0:00
Non-English extensions	Ź, ź	− − · · − · Menu 0:00
Non-English extensions	Ż, ż	− − · · − Menu 0:00

Prosigns

Main article: 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 text formatting actions.

Symbol representations

The symbols !, $ and & are not defined inside the ITU recommendation on Morse code, but conventions for them exist. The @ symbol was formally added in 2004.

Exclamation mark

There is no standard representation for the exclamation mark (!), although the KW digraph (▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄) was proposed in the 1980s by the Heathkit Company (a vendor of assembly 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 prefer the older MN digraph (▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄) carried over from American landline telegraphy code.

Currency symbols

• The ITU has never codified formal Morse Code representations for currencies as the ISO 4217 Currency Codes are preferred for transmission.
• The $ sign code was represented in the Phillips Code, a huge collection of abbreviations used on land line telegraphy, as SX.

Ampersand

• The representation of the & sign given above, often shown as AS, is also the Morse prosign for wait. In addition, the American landline representation of an ampersand was similar to "ES" (▄▄▄▄▄▄▄▄▄▄▄) and hams have carried over this usage as a synonym for "and" (WX HR COLD ES RAINY, "the weather here is cold & rainy").

Keyboard AT @

• On May 24, 2004 — the 160th 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 AC digraph (▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄).
• This sequence was reportedly chosen to represent "A[T] C[OMMERCIAL]" or a letter "a" inside a swirl represented by a "C".^[58] The new character facilitates sending email addresses by Morse code and is notable since it is the first official addition to the Morse set of characters since World War I.

Non-Latin extensions

Main article: Other alphabets in Morse code

For 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 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. For 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 way (A, O, E, I, T, M, N, R, K, etc.). Bulgarian alphabet contains 30 characters, which exactly match all possible combinations of 1, 2, 3, and 4 dots and dashes (Russian Ы is used as Bulgarian Ь, Russian Ь is used as Bulgarian Ъ). Russian requires 2 extra characters, "Э" and "Ъ" which are encoded with 5 elements.

Unusual variants

During early World War 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 restored by Spring 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 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.^[59]

Other forms of 'Fractional Morse' or 'Fractionated Morse' have emerged.^[60]

Decoding software

Decoding software for Morse code ranges from software-defined wide-band radio receivers coupled to the Reverse Beacon Network,^[61] which decodes signals and detects CQ messages on ham bands, to smartphone applications.^[62]

See also

• ACP-131
• CW Operators' Club
• Guglielmo Marconi
• High-speed telegraphy
• Hog morse
• Instructograph
• Morse code abbreviations
• Morse code mnemonics
• NATO phonetic alphabet
• Tap code
• Alfred Vail
• Wabun code
• Wireless telegraphy
• Theodore Roosevelt McElroy

References

1. ^ Jump up to: ^{a b c d} "International Morse code Recommendation ITU-R M.1677-1". itu.int. International Telecommunication Union. October 2009. Archived from the original on 6 November 2012. Retrieved 23 December 2011.
2. ^ F. S. Beechey, Electro-Telegraphy, London: E. & F. N. Spon, 1876, p. 71
3. ^ F. J. Camm, Radio Engineer's Pocket Book, 2nd ed., Chemical Publishing Co., 1941, p. 72
4. ^ Headquarters, Department of the Army, TM 11-459, International Morse Code (Instructions), Washington, D.C.: U.S.G.P.O., 1968 pp. 7-8
5. ^ W.H. Preece, J. Sivewright, Telegraphy, London: Longmans, Green and Co., 1891, p. 40
6. ^ U.S. Army, FM 24-5, Signal Communication, 1939, pp. 83, 101-108, 227
7. ^ W. L. Everitt, Communication Engineering, 2nd ed. New York: McGraw-Hill, 1937, p. 6
8. ^ Editors and Engineers, The "Radio" Handbook, Los Angeles: Editors and Engineers, 1942, p. 180
9. ^ Headquarters, Department of the Army, TM 11-459, International Morse Code (Instructions), Washington, D.C.: U.S.G.P.O., 1968, pp. 6-7
10. ^ U. S. Navy, Bureau of Naval Personnel, Radioman 3 & 2, Washington, D.C.: U.S.G.P.O., 1957, pp. 105-111
11. ^ War Department, TM 11-459, Instructions for Learning International Morse Characters, 1943, pp. 52, 68-72
12. ^ Fahie, John Joseph (1884). A History of Electric Telegraphy, to the Year 1837 (PDF). E. & F.N. Spon. Archived (PDF) from the original on 15 July 2017. Retrieved 21 November 2017.
13. ^ Engineer-in-Chief's Office (1938) [1919], Elementary Principles of Telegraphy and Systems up to Morse Duplex, Technical Pamphlets for Workmen, London: His Majesty's Stationery Office, p. 6
14. ^ Freebody 1959, pp. 28-29.
15. ^ Burns 2004, p. 79
16. ^ Burns 2004, p. 84
17. ^ "Learning Morse Code". Arrl.org. Archived from the original on 20 September 2017. Retrieved 1 December 2017.
18. ^ L. Peter Carron, "Morse Code: The Essential Language", Radio amateur's library, issue 69, American Radio Relay League, 1986 ISBN 0-87259-035-6.
19. ^ R. J. Eckersley, Amateur radio operating manual, Radio Society of Great Britain, 1985 ISBN 0-900612-69-X.
20. ^ "Iddy-umpty". Oxford English Dictionary. Retrieved 22 October 2016. (available online to subscribers)
21. ^ Annual Report of the Board of Regents of the Smithsonian Instution for 1878, pp. 358–360, Smithsonian Institution, 1879.
22. ^ Captain Linwood S. Howeth (1963). History of Communications-Electronics in the United States: Early Navy Efforts to Develop Aircraft Radio Navy.
23. ^ "K2TQN Vintage Radio Column". K2tqn.com. Archived from the original on 11 September 2017. Retrieved 1 December 2017.
24. ^ Jump up to: ^{a b} "How the Zeppelin Raiders Are Guided by Radio Signals". Popular Science Monthly. April 1918. pp. 632–634. Retrieved March 4, 2018. Cite magazine requires |magazine= (help)
25. ^ "An obituary for Morse code" Archived 2017-03-30 at the Wayback Machine, The Economist, January 23, 1999.
26. ^ "Maritime Radio Historical Society". radiomarine.org. Archived from the original on 25 January 2018. Retrieved 1 December 2017.
27. ^ "Morse code training in the Air Force". Swling.com. 10 December 2015. Archived from the original on 2 July 2017. Retrieved 1 December 2017.
28. ^ "Amendments to the International Aeronautical and Maritime Search and Rescue (IAMSAR) Manual" (PDF). Uscg.mil. Retrieved 1 December 2017.
29. ^ Jump up to: ^{a b} "Radiotelegraph Operator License (T)". fcc.gov. Federal Communications Commission. Archived from the original on January 13, 2015. Retrieved January 21, 2015.
30. ^ "Maritime Radio Historical Society". radiomarine.org. Archived from the original on 9 October 2017. Retrieved 1 December 2017.
31. ^ Perera, Tom. "The "Morse" Code and the Continental Code". W1TP Telegraph & Scientific Instruments Museums. Archived from the original on 9 December 2011. Retrieved 23 December 2011.
32. ^ Jump up to: ^{a b} "The Art & Skill of Radio Telegraphy" (PDF). 2002. Archived (PDF) from the original on 2012-02-26. Retrieved 2013-06-14.
33. ^ "Extremely High Speed Club official web page". Morsecode.nl. Archived from the original on 28 June 2017. Retrieved 1 December 2017.
34. ^ "Chapter 1. Air Navigation". faa.gov. January 3, 2015. Archived from the original on December 1, 2014. Retrieved January 21, 2015.
35. ^ "COM 3.2, Canadian AIM" (PDF). Archived from the original (PDF) on November 22, 2013.
36. ^ "WG - WINNIPEG". Pilotnav.com. Archived from the original on 2 December 2017. Retrieved 1 December 2017.
37. ^ "IARUWeb: The International Amateur Radio Union". Archived from the original on September 6, 2012.
38. ^ "Italy Joins No-Code Ranks as FCC Revives Morse Debate in the US". The ARRL Letter. 24 (31). August 12, 2005. Archived from the original on November 5, 2011. Retrieved 2012-04-02.
39. ^ "1998 Biennial Regulatory Review — Amendment of Part 97 of the Commission's Amateur Service Rules" (PDF). Archived from the original (PDF) on October 31, 2005. Retrieved December 4, 2005.
40. ^ "Aeronautical Information Manual (AIM)". Archived from the original on September 4, 2009. Retrieved 2007-12-10.
41. ^ "Prosigns". Qsl.net. QTH.Com. Archived from the original on September 24, 2015. Retrieved January 21, 2015.
42. ^ "#FactsOnly: The Most Interesting Things You Didn't Know About Nokia". Complex. Retrieved 2018-05-13.
43. ^ Nokia files patent for Morse Code-generating cellphone Archived 2017-06-25 at the Wayback Machine, 12 March 2005, Engadget.
44. ^ "Android Accessibility Help: Use Morse Code". Google. 2018. Retrieved 21 December 2018.
45. ^ Dennis W. Ross, "Morse Code: A Place in the Mind," QST, March, 1992, p. 51.
46. ^ Ronald J. Curt, "In the Blink of an Eye," QST, July 1990 p. 44.
47. ^ Donna Burch, "Morse Code from the Heart," QST July 1990 p. 45.
48. ^ Ken Beauchamp, History of Telegraphy, Institution of Electrical Engineers IET, 2001 ISBN 0852967926 page 150
49. ^ Title 47 Code of Federal Regulations §13.207(c) and Title 47 Code of Federal Regulations §13.209(d)
50. ^ 47 CFR §13.203(b)
51. ^ Title 47 Code of Federal Regulations §97.503, 1996 version
52. ^ "Fastest speed for a morse code transmission". Guinnessworldrecords.com. Archived from the original on 3 July 2017. Retrieved 1 December 2017.
53. ^ "A Standard for Morse Timing Using the Farnsworth Technique" (PDF). Arrl.org. Archived (PDF) from the original on 25 January 2018. Retrieved 1 December 2017.
54. ^ "Custom Farnsworth Spacing Configuration". Winmorse.com. Archived from the original on 2016-03-04. Retrieved 2013-11-21.
55. ^ "Girl Guiding by Lord Baden-Powell" (PDF). Pearson. 1938. Archived (PDF) from the original on 2015-10-06. Retrieved 2015-09-06. Some people find it easier to remember the does [sic] and dashes by picturing them as forming the letters— thus:— (p61)
56. ^ Glenn Stanley, The Cambridge Companion to Beethoven, p.269, Cambridge University Press, 2000 ISBN 0-521-58934-7.
57. ^ William Emmett Studwell, The Americana Song Reader, p.62, Routledge, 1997 ISBN 0-7890-0150-0.
58. ^ "International Morse Code Gets a New ITU Home, New Character". Archived from the original on September 30, 2007. Retrieved February 27, 2007.
59. ^ Wythoff, Grant (July 2014). "The Invention of Wireless Cryptography". The Appendix: Futures of the Past. 2 (3). Archived from the original on 2014-12-08. Retrieved 2015-01-28.
60. ^ "Fractionated Morse, and Other Oddities". Quadibloc.com. Retrieved 2013-11-21.
61. ^ "Welcome! - Reverse Beacon Network". Reversebeacon.net. Archived from the original on 12 September 2017. Retrieved 1 December 2017.
62. ^ "Morse Decoder Test – iPhone / iPad | Gerolf Ziegenhain". Gerolfziegenhain.wordpress.com. 2013-05-20. Archived from the original on 2017-07-27. Retrieved 2016-09-17.

Bibliography

• Burns, R. W. (2004), Communications: an international history of the formative years, Institution of Electrical Engineers, ISBN 0-86341-327-7
• Freebody, J. W. (1959), "Historical Survey of Telegraphy", Telegraphy, London: Sir Isaac Pitman & Sons, Ltd.

External links

Wikimedia Commons has media related to Morse code.

• Morse code at Curlie
• "Everyone Knows Morse". TV Tropes.. Includes a list of uses and appearances of Morse Code in movies, television episodes, and other popular culture.
• Morse Code resources
• Morse code MP3 practice files. 200 hours of at increasing speeds plus an ASCII-to-CW file generator program.
• International Morse Code, Hand Sending US Army training video 1966.
• Morse Code Radio Operator Training "Technique of Hand Sending" US Navy 1944.
• Codes of the World

show v t e International Morse code
Transmission methods	Electrical telegraph On–off keying Continuous wave Modulated continuous wave Heliograph Signal lamp
Notable signals	SOS CQD Morse code mnemonics Prosigns for Morse code Morse code abbreviations Q code Z code
Other writing systems in Morse code	American Morse code Greek alphabet Cyrillic script Russian Hebrew script Arabic script Wabun code Chinese telegraph code

show v t e Telecommunications
History	Beacon Broadcasting Cable protection system Cable TV Communications satellite Computer network Data compression audio DCT image video Digital media Internet video online video platform social media streaming Drums Edholm's law Electrical telegraph Fax Heliographs Hydraulic telegraph Information Age Information revolution Internet Mass media Mobile phone Smartphone Optical telecommunication Optical telegraphy Pager Photophone Prepaid mobile phone Radio Radiotelephone Satellite communications Semaphore Semiconductor device MOSFET transistor Smoke signals Telecommunications history Telautograph Telegraphy Teleprinter (teletype) Telephone The Telephone Cases Television digital streaming Undersea telegraph line Videotelephony Whistled language Wireless revolution
Pioneers	Nasir Ahmed Edwin Howard Armstrong Mohamed M. Atalla John Logie Baird Paul Baran John Bardeen Alexander Graham Bell Tim Berners-Lee Jagadish Chandra Bose Walter Houser Brattain Vint Cerf Claude Chappe Yogen Dalal Donald Davies Lee de Forest Philo Farnsworth Reginald Fessenden Elisha Gray Oliver Heaviside Erna Schneider Hoover Harold Hopkins Internet pioneers Bob Kahn Dawon Kahng Charles K. Kao Narinder Singh Kapany Hedy Lamarr Innocenzo Manzetti Guglielmo Marconi Robert Metcalfe Antonio Meucci Jun-ichi Nishizawa Radia Perlman Alexander Stepanovich Popov Johann Philipp Reis Claude Shannon Henry Sutton Nikola Tesla Camille Tissot Alfred Vail Charles Wheatstone Vladimir K. Zworykin
Transmission media	Coaxial cable Fiber-optic communication optical fiber Free-space optical communication Molecular communication Radio waves wireless Transmission line data transmission circuit telecommunication circuit
Network topology and switching	Bandwidth Links Nodes terminal Network switching (circuit packet) Telephone exchange
Multiplexing	Space-division Frequency-division Time-division Polarization-division Orbital angular-momentum Code-division
Networks	ARPANET BITNET Cellular network Computer CYCLADES Ethernet FidoNet Internet Internet2 ISDN LAN Mobile NGN NPL network Public Switched Telephone Radio Telecommunications equipment Television Telex WAN Wireless network World Wide Web
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show v t e Character encodings
Early telecommunications	ASCII ISO/IEC 646 ISO/IEC 6937 / ITU T.51 ITU T.61 BCDIC Baudot code Morse code Telegraph code Wabun code Special telegraphy codes Non-Latin Chinese Cyrillic Needle telegraph codes
ISO/IEC 8859	Approved -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -13 -14 -15 -16 Abandoned -12 Adaptations ISO-IR-182 ISO-IR-200 ISO-IR-201 Proposed but not approved ISO-IR-111 ISO-IR-197 French/Dutch/Turkish draft
Bibliographic use	ANSEL ISO 5426 / 5426-2 / 5427 / 5428 / 6438 / 6861 / 6862 / 10585 / 10586 / 10754 / 11822 MARC-8
National standards	ArmSCII BraSCII CNS 11643 ELOT 927 GOST 10859 GB 18030 HKSCS I.S. 434 ISCII JIS X 0201 JIS X 0208 JIS X 0212 JIS X 0213 KOI-7 KPS 9566 KS X 1001 PASCII SI 960 TIS-620 TSCII VISCII VSCII YUSCII
ISO/IEC 2022	7-bit CN CN-EXT JP JP-EXT JP-1 JP-2 JP-3 KR ISO/IEC 4873 ISO/IEC 8859 ISO/IEC 10367 Extended Unix Code / EUC CN KR JP TW CCCII
MacOS code pages ("scripts")	Armenian Arabic Barents Cyrillic Celtic CentEuro ChineseSimp / EUC-CN ChineseTrad / Big5 Croatian Cyrillic Devanagari Dingbats Farsi (Persian) Gaelic Georgian Greek Gujarati Gurmukhi Hebrew Iceland Inuit Japanese / ShiftJIS Keyboard Korean / EUC-KR Latin (Kermit) Maltese/Esperanto Ogham / I.S. 434 Roman Romanian Sámi Symbol Thai / TIS-620 Turkish Turkic Cyrillic Ukrainian VT100
DOS code pages	100 111 112 113 151 152 161 162 163 164 165 166 210 220 301 437 449 489 620 667 668 707 708 709 710 711 714 715 720 721 737 768 770 771 772 773 774 775 776 777 778 790 850 851 852 853 854 855/872 856 857 858 859 860 861 862 863 864/17248 865 866/808 867 868 869 874/1161/1162 876 877 878 881 882 883 884 885 891 895 896 897 898 899 900 903 904 906 907 909 910 911 926 927 928 929 932 934 936 938 941 942 943 944 946 947 948 949 950/1370 951 966 991 1034 1039 1040 1041 1042 1043 1044 1046 1086 1088 1092 1093 1098 1108 1109 1114 1115 1116 1117 1118 1119 1125/848 1126 1127 1131/849 1139 1167 1168 1300 1351 1361 1362 1363 1372 1373 1374 1375 1380 1381 1385 1386 1391 1392 1393 1394 57781 58152 58210 58335 59234 59829 60258 60853 61282 62306 CS Indic CSX Indic CSX+ Indic CWI-2 Iran System Kamenický KOI8 Mazovia MIK
IBM AIX code pages	367 371 806 813 819 895 896 912 913 914 915 916 919 920 921/901 922/902 923 952 953 954 955 956 957 958 959 960 961 963 964 965 970 971 1004 1006 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1029 1036 1089 1111 1124 1129/1163 1133 1350 1382 1383
IBM Apple MacIntosh emulations	1275 1280 1281 1282 1283 1284 1285 1286
IBM Adobe emulations	1038 1276 1277
IBM DEC emulations	1020 1021 1023 1090 1100 1101 1102 1103 1104 1105 1106 1107 1287 1288
IBM HP emulations	1050 1051 1052 1053 1054 1055 1056 1057 1058
Windows code pages	CER-GS 874/1162 (TIS-620) 932/943 (Shift JIS) 936/1386 (GBK) 950/1370 (Big5) 949/1363 (EUC-KR) 1169 1174 Extended Latin-8 1200 (UTF-16LE) 1201 (UTF-16BE) 1250 1251 1252 1253 1254 1255 1256 1257 1258 1261 1270 54936 (GB18030) 65001 (UTF-8)
EBCDICcode pages	1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37/1140 37-2 38 39 40 251 252 254 256 257 258 259 260 264 273/1141 274 275 276 277/1142 278/1143 279 280/1144 281 282 283 284/1145 285/1146 286 287 288 289 290 293 297/1147 298 300 310 320 321 322 330 351 352 353 355 357 358 359 360 361 363 382 383 384 385 386 387 388 389 390 391 392 393 394 395 410 420/16804 421 423 424/8616/12712 425 435 500/1148 803 829 833 834 835 836 837 838/1160 839 870/1110/1153 871/1149 875/4971/9067 880 881 882 883 884 885 886 887 888 889 890 892 893 905 918 924 930/1390 931 933/1364 935/1388 937/1371 939/1399 1001 1002 1003 1005 1007 1024 1025/1154 1026/1155 1027 1028 1030 1031 1032 1033 1037 1047 1068 1069 1070 1071 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1087 1091 1097 1112/1156 1113 1122/1157 1123/1158 1130/1164 1132 1136 1137 1150 1151 1152 1159 1165 1166 1278 1279 1303 1364 1376 1377 JEF KEIS
Platform specific	Acorn Adobe Standard Adobe Latin 1 Amstrad CPC Apple I Apple II Apple III ATASCII Atari ST BICS Casio calculators CDC Compucolor II DEC Radix-50 DEC MCS/NRCS DG International ELWRO-Junior FIELDATA GEM GEOS GSM 03.38 HP Roman Extension HP Roman-8 HP Roman-9 HP FOCAL HP RPL LICS LMBCS Mattel Aquarius Minitel MSX NEC APC NeXT OricSCII PCW PETSCII Sega SC-3000 Sharp calculators Sharp MZ Sinclair QL Teletext TI calculators TRS-80 Ventura International Ventura Symbol Videotex WISCII XCCS ZX80 ZX81 ZX Spectrum
Unicode / ISO/IEC 10646	UTF-1 UTF-7 UTF-8 UTF-16 (UTF-16LE/UTF-16BE) / UCS-2 UTF-32 (UTF-32LE/UTF-32BE) / UCS-4 UTF-EBCDIC GB 18030 BOCU-1 CESU-8 SCSU
TeX typesetting system	Cork LGR LY1 OML OMS OMX OT1 OT2 OT3 OT4 T2A T2B T2C T2D T3 T4 T5 TS1 TS3 U X2
Miscellaneous code pages	ABICOMP APL 293 310 (Graphic Escape) 351 (GDDM) 907 (OEM) ISO-IR-68 ARIB STD-B24 HZ IEC-P27-1 INIS 7-bit 8-bit Cyrillic ISO-IR-169 ISO 2033 Johab SEASCII Stanford/ITS TACE16 TRON UTF-5 UTF-6 WTF-8
Related topics	Code page Control character (C0 C1) CCSID Character encodings in HTML Charset detection Han unification Hardware ISO 6429/IEC 6429/ANSI X3.64 Mojibake
Character sets

show v t e Types of writing systems
Overview History of writing Grapheme Lists Writing systems undeciphered inventors constructed Languages by writing system / by first written accounts
hide Types show Abjads Numerals Aramaic Hatran Arabic Egyptian hieroglyphs Pitman shorthand Hebrew Ashuri Cursive Rashi Solitreo Tifinagh Manichaean Nabataean Old North Arabian Pahlavi Pegon Phoenician Paleo-Hebrew Proto-Sinaitic Psalter Pahlavi Punic Samaritan South Arabian Zabur Musnad Sogdian Syriac ʾEsṭrangēlā Serṭā Maḏnḥāyā Teeline Shorthand Ugaritic show Abugidas Brahmic Northern Bengali Bhaikshuki Bhujinmol Brāhmī Devanāgarī Dogri Gujarati Gupta Gurmukhī Kaithi Kalinga Kharosthi Khojki Khudawadi Laṇḍā Lepcha Limbu Mahajani Meitei Modi Multani Nāgarī Nandinagari Odia ʼPhags-pa Pracalit (Newar) Ranjana Sharada Saurashtra Siddhaṃ Soyombo Sylheti Nagari Takri Tibetan Uchen Umê Tirhuta Tocharian Zanabazar Square Zhang-Zhung Drusha Marchen Marchung Pungs-chen Pungs-chung Southern Ahom Balinese Batak Baybayin Bhattiprolu Buhid Burmese Chakma Cham Grantha Goykanadi Hanunuo (Hanunó'o) Javanese Kadamba Kannada Karen Kawi Khmer Kulitan Lanna Lao Leke Lontara Malayalam Maldivian Dhives Akuru Eveyla Akuru Thaana Mon (Old Mon) Pallava Pyu Rejang Rencong Sinhala Sundanese (Old Sundanese) Tagbanwa Tai Le Tai Tham Tai Viet Tamil Telugu Thai Tigalari Vatteluttu Kolezhuthu Malayanma Others Boyd's syllabic shorthand Canadian syllabics Blackfoot Déné syllabics Fox I Geʽez Gunjala Gondi Japanese Braille Jenticha Kayah Li Kharosthi Mandombe Masaram Gondi Meroitic Miao Mwangwego Sorang Sompeng Pahawh Hmong Thomas Natural Shorthand Warang Citi show Alphabets Linear Abkhaz Adlam Armenian Avestan Avoiuli Bassa Vah Borama Carian Caucasian Albanian Coorgi–Cox alphabet Coptic Cyrillic Deseret Duployan shorthand Chinook writing Early Cyrillic Eclectic shorthand Elbasan Etruscan Evenki Fox II Fraser Gabelsberger shorthand Garay Georgian Asomtavruli Nuskhuri Mkhedruli Glagolitic Gothic Gregg shorthand Greek Greco-Iberian alphabet Hangul Hanifi IPA Kaddare Klingon Latin Beneventan Blackletter Carolingian minuscule Fraktur Gaelic Insular Kurrent Merovingian Sigla Sütterlin Tironian notes Visigothic Luo Lycian Lydian Manchu Mandaic Medefaidrin Molodtsov Mongolian Mru Neo-Tifinagh New Tai Lue N'Ko Ogham Oirat Ol Chiki Old Hungarian Old Italic Old Permic Orkhon Old Uyghur Osage Osmanya Pau Cin Hau Runic Anglo-Saxon Cipher Dalecarlian Elder Futhark Younger Futhark Gothic Marcomannic Medieval Staveless Sidetic Shavian Somali Tifinagh Vagindra Visible Speech Vithkuqi Wancho Zaghawa Non-linear Braille Maritime flags Telegraph code New York Point Flag semaphore Moon type show Ideograms and pictograms Adinkra Aztec Blissymbol Dongba Ersu Shaba Emoji IConji Isotype Kaidā Míkmaq Mixtec New Epoch Notation Painting Nsibidi Ojibwe Hieroglyphs Siglas poveiras Testerian Yerkish Zapotec show Logograms Chinese family of scripts Chinese Characters Simplified Traditional Oracle bone script Bronze Script Seal Script large small bird-worm Hanja Idu Kanji Chữ nôm Zhuang Chinese-influenced Jurchen Khitan large script Sui Tangut Cuneiform Akkadian Assyrian Elamite Hittite Luwian Sumerian Other logo-syllabic Anatolian Bagam Cretan Isthmian Maya Proto-Elamite Yi (Classical) Logo-consonantal Demotic Hieratic Hieroglyphs Numerals Hindu-Arabic Abjad Attic (Greek) Muisca Roman show Semi-syllabaries Full Celtiberian Northeastern Iberian Southeastern Iberian Khom Redundant Espanca Pahawh Hmong Khitan small script Southwest Paleohispanic Zhuyin fuhao show Somacheirograms ASLwrite SignWriting si5s Stokoe Notation show Syllabaries Afaka Bamum Bété Byblos Canadian Aboriginal Cherokee Cypriot Cypro-Minoan Ditema tsa Dinoko Eskayan Geba Great Lakes Algonquian Iban Japanese Hiragana Katakana Man'yōgana Hentaigana Sogana Jindai moji Kikakui Kpelle Linear B Linear Elamite Lisu Loma Nüshu Nwagu Aneke script Old Persian Cuneiform Sumerian Vai Woleai Yi (Modern) Yugtun
show v t e Braille ⠃⠗⠁⠊⠇⠇⠑ Braille cell 1829 braille International uniformity ASCII braille Unicode braille patterns Braille scripts French-ordered scripts (see for more) Albanian Amharic Arabic Armenian Azerbaijani Belarusian Bharati Devanagari (Hindi / Marathi / Nepali) Bengali Punjabi Sinhala Tamil Urdu etc. Bulgarian Burmese Cambodian Cantonese Catalan Chinese (Mandarin, mainland) Czech Dutch Dzongkha (Bhutanese) English (Unified English) Esperanto Estonian Faroese French Georgian German Ghanaian Greek Guarani Hawaiian Hebrew Hungarian Icelandic Inuktitut (reassigned vowels) Iñupiaq IPA Irish Italian Kazakh Kyrgyz Latvian Lithuanian Maltese Mongolian Māori Navajo Nigerian Northern Sami Persian Philippine Polish Portuguese Romanian Russian Samoan Scandinavian Slovak South African Spanish Tatar Taiwanese Mandarin (largely reassigned) Thai & Lao (Japanese vowels) Tibetan Turkish Ukrainian Vietnamese Welsh Yugoslav Reordered scripts Algerian Braille (obsolete) Frequency-based scripts American Braille (obsolete) Independent scripts Japanese Korean Two-Cell Chinese Eight-dot scripts Luxembourgish Kanji Gardner–Salinas braille codes (GS8) Symbols in braille Braille music Canadian currency marks Computer Braille Code Gardner–Salinas braille codes (science; GS8/GS6) International Phonetic Alphabet (IPA) Nemeth braille code Braille technology Braille e-book Braille embosser Braille translator Braille watch Mountbatten Brailler Optical braille recognition Perforation Perkins Brailler Refreshable braille display Slate and stylus Braigo Persons Louis Braille Charles Barbier Valentin Haüy Thakur Vishva Narain Singh Sabriye Tenberken William Bell Wait Organisations Braille Institute of America Braille Without Borders Japan Braille Library National Braille Association Blindness organizations Schools for the blind American Printing House for the Blind Other tactile alphabets Decapoint Moon type New York Point Night writing Vibratese Related topics Accessible publishing Braille literacy RoboBraille
show v t e Electronic writing systems Emoticons Emoji iConji Leet Unicode show v t e Internet slang dialects 3arabizi Alay (Indonesia) Denglisch Doge DoggoLingo Fingilish (Persian) Greeklish Gyaru-moji (Japan) Jejemon (Philippines) Leet ("1337") Lolspeak / LOLspeak / Kitteh Martian language (Chinese) Miguxês (Portuguese) O RLY? Padonkaffsky jargon (Russian) Translit Volapuk See alsoEnglish internet slang(at Wiktionary) SMS language

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• American inventions
• Morse code
• Latin-script representations
• 1848 introductions
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