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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. 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.
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. 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. 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.
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. Because many non-English natural languages use other than the 26 Roman letters, Morse alphabets have been developed for those languages. 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. 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. 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.
The American artist Samuel F. 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 , 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 and demonstrated it on the London and Birmingham Railway, making it the first commercial telegraph. Carl Friedrich Gauss and Wilhelm Eduard Weber as well as Carl August von Steinheil used codes with varying word lengths for their telegraphs.
In , Cooke and Wheatstone built a telegraph that printed the letters from a wheel of typefaces struck by a hammer. The Morse system for telegraphy , which was first used in about , 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 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. This code, first used in , became known as Morse landline code or American Morse code.
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.
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". The Morse code, as it is used internationally today, was derived from a much-refined proposal by Friedrich Clemens Gerke in 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. This finally led to the International Morse code in 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 , not the code shown in the table which was developed in the s. In the s, 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 s. Although previous transmitters were bulky and the spark gap system of transmission was difficult to use, there had been some earlier attempts. In , the US Navy experimented with sending Morse from an airplane. However, there was little aeronautical radio in general use during World War I , and in the s, there was no radio system used by such important flights as that of Charles Lindbergh from New York to Paris in 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 on the Southern Cross , one of its four crewmen was its radio operator who communicated with ground stations via radio telegraph.
Beginning in the s, 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. Army in France and Belgium in , and in southern Germany in Morse code was used as an international standard for maritime distress until when it was replaced by the Global Maritime Distress and Safety System. When the French Navy ceased using Morse code on January 31, , the final message transmitted was "Calling all.
This is our last cry before our eternal silence. Similarly, a few U. 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. 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. 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. 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.
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. 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 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. Morse code has been in use for more than 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 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.
Translation of "alfabet morse'a" in English