Morse code is a character encoding scheme used in telecommunication that encodes text characters as standardized sequences of two different signal durations called dots and dashes or dits and dahs. 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. There is no distinction between lower case letters; each Morse code symbol is formed by a sequence of 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, the words are separated by a space equal to seven dots. To increase the efficiency of encoding, Morse code was designed so that the length of each symbol is 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 transmitted at the highest rate that the receiver is capable of decoding; the Morse code transmission rate is specified in groups per minute referred to as words per minute. Morse code is transmitted by on-off keying of an information carrying medium such as electric current, radio waves, visible light or sound waves; the current or wave is present during time period of the dot or dash and absent during the time between dots and dashes. Morse code can be memorized, 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, 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. 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 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. 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; the American artist Samuel F. B. Morse, the American physicist Joseph Henry, 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, therefore, developed an early forerunner to the modern International Morse code. William Cooke and Charles Wheatstone in England 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 as well as Carl August von Steinheil 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. The Morse system for telegraphy, 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, 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. The shorter marks were called "dots" and the longer ones "dashes", the letters most used were assigned the shorter sequences of dots and dashes; this code was used since 1844 and became known as Morse lan
The Baudot code, invented by Émile Baudot, is a character set predating EBCDIC and ASCII. It was the predecessor to the International Telegraph Alphabet No. 2, the teleprinter code in use until the advent of ASCII. Each character in the alphabet is represented by a series of five bits, sent over a communication channel such as a telegraph wire or a radio signal; the symbol rate measurement is known as baud, is derived from the same name. Technically, five-bit codes began in the 17th century, when Francis Bacon developed the cipher now called Bacon's cipher; the cipher was not designed for machine telecommunications and, although in theory it could be adapted to that purpose, it only covered 24 of the 26 letters of the English alphabet and contained no punctuation, numbers or control characters, rendering it of little use. Baudot invented his original code in 1870 and patented it in 1874, it was a 5-bit code, with equal on and off intervals, which allowed for transmission of the Roman alphabet, included punctuation and control signals.
It was based on an earlier code developed by Carl Friedrich Gauss and Wilhelm Weber in 1834. It was a Gray code, the code by itself was not patented because French patent law does not allow concepts to be patented. Baudot's original code was adapted to be sent from a manual keyboard, no teleprinter equipment was constructed that used it in its original form; the code was entered on a keyboard which had just five piano-type keys and was operated using two fingers of the left hand and three fingers of the right hand. Once the keys had been pressed, they were locked down until mechanical contacts in a distributor unit passed over the sector connected to that particular keyboard, when the keyboard was unlocked ready for the next character to be entered, with an audible click to warn the operator. Operators had to maintain a steady rhythm, the usual speed of operation was 30 words per minute; the table "shows the allocation of the Baudot code, employed in the British Post Office for continental and inland services.
A number of characters in the continental code are replaced by fractionals in the inland code. Code elements 1, 2 and 3 are transmitted by keys 1, 2 and 3, these are operated by the first three fingers of the right hand. Code elements 4 and 5 are transmitted by keys 4 and 5, these are operated by the first two fingers of the left hand."Baudot's code became known as the International Telegraph Alphabet No. 1. It is no longer used. In 1901, Baudot's code was modified by Donald Murray, prompted by his development of a typewriter-like keyboard; the Murray system employed an intermediate step. At the receiving end of the line, a printing mechanism would print on a paper tape, and/or a reperforator could be used to make a perforated copy of the message; as there was no longer a connection between the operator's hand movement and the bits transmitted, there was no concern about arranging the code to minimize operator fatigue, instead Murray designed the code to minimize wear on the machinery, assigning the code combinations with the fewest punched holes to the most used characters.
For example, the one-hole letters are E and T. The ten two-hole letters are AOINSHRDLZ similar to the "Etaoin shrdlu" order used in Linotype machines. Ten more letters have three holes, the four-hole letters are VXKQ; the Murray code introduced what became known as "format effectors" or "control characters" – the CR and LF codes. A few of Baudot's codes moved to the positions where they have stayed since: the NULL or BLANK and the DEL code. NULL/BLANK was used as an idle code for when no messages were being sent, but the same code was used to encode the space separation between words. Sequences of DEL codes were used at start or end of messages or between them, allowing easy separation of distinct messages.. Early British Creed machines used the Murray system. Murray's code was adopted by Western Union which used it until the 1950s, with a few changes that consisted of omitting some characters and adding more control codes. An explicit SPC character was introduced, in place of the BLANK/NULL, a new BEL code rang a bell or otherwise produced an audible signal at the receiver.
Additionally, the WRU or "Who aRe yoU?" Code was introduced, which caused a receiving machine to send an identification stream back to the sender. In 1924, the CCITT introduced the International Telegraph Alphabet No. 2 code as an international standard, based on the Western Union code with some minor changes. The US standardized on a version of ITA2 called the American Teletypewriter code, the basis for 5-bit teletypewriter codes until the debut of 7-bit ASCII in 1963; some code points were reserved for national-specific usage. The code position assigned to Null was in fact used only for the idle state of teleprinters. During long periods of idle time, the impulse rate was not synchronized between both devices. To start a message it was first necessary to calibrate the impulse rate a sequence of timed "mark" pu
JIS X 0208
JIS X 0208 is a 2-byte character set specified as a Japanese Industrial Standard, containing 6879 graphic characters suitable for writing text, place names, personal names, so forth in the Japanese language. The official title of the current standard is 7-bit and 8-bit double byte coded KANJI sets for information interchange, it was established as JIS C 6226 in 1978, has been revised in 1983, 1990, 1997. It is called Code page 952 by IBM; the 1978 version is called Code page 955 by IBM. The character set JIS X 0208 establishes is for the purpose of information interchange between data processing systems and the devices connected to them, or mutually between data communication systems; this character set can be used for text processing. Partial implementations of the character set are not considered compatible; because there are places where such things have happened as the original drafting committee of the first standard taking care to separate characters between level 1 and level 2 and the second standard shuffling some variant characters between the levels, at least in the first and second standards, it is conjectured that non-kanji and level 1-only implementation Japanese computer systems were at one time considered for development.
However, such implementations have never been specified as compatible, though an example like the early NEC PC-9801 did exist. Though there are provisions in the JIS X 0208:1997 standard concerning compatibility, at the present time, it is considered that this standard neither certifies compatibility nor is it an official manufacturing standard that amounts to a declaration of self-compatibility. De facto, JIS X 0208-“compatible” products are not considered to exist. Terminology such as “conformant” and “support” is included in JIS X 0208, but the semantics of these terms vary from person to person; the first encoding byte corresponds to 32 in decimal. Hence, the code set starting with 0x21 has a row number of 1, its cell 1 has a continuation byte of 0x21, so forth; some vendors use different Unicode mapping for this set than the one below. For example, Microsoft maps kuten 1-29 to U+2015, whereas Apple maps it to U+2014. Microsoft maps kuten 1-61 to U+FF0D, Apple maps it to U+2212. Unicode mapping of the wave dash differs between vendors.
See the cells with footnotes below. ASCII and JISCII punctuation may use alternative mappings to the Halfwidth and Fullwidth Forms block if used in an encoding which combines JIS X 0208 with ASCII or with JIS X 0201, such as Shift JIS, EUC-JP or ISO 2022-JP. Most of the characters in this set were added in 1983, except for characters 0x2221–0x222E, which were included in the original 1978 version of the standard. Characters in this set may use alternative Unicode mappings to the Halfwidth and Fullwidth Forms block if used in an encoding which combines JIS X 0208 with ASCII or with JIS X 0201, such as EUC-JP, Shift JIS or ISO 2022-JP; this row contains basic support for the modern Greek alphabet, without diacritics or the final sigma. This row contains the modern Russian alphabet and is not sufficient for representing other forms of the Cyrillic script. All characters in this set were added in 1983, were not present in the original 1978 revision of the standard. Rows 9 through 15 of the JIS X 0208 standard are left empty.
However, the following layout for row 13, first introduced by NEC, is a common extension. It is used by Windows-932, by the PostScript variant of MacJapanese, by JIS X 0213. Unlike the other extensions made by Windows-932/WHATWG and JIS X 0213, the two match rather than colliding, so decoding of most of this row is better supported than the other extensions made by JIS X 0213. In order to represent code points, column/line numbers are used for one-byte codes and kuten numbers are used for two-byte codes. For a way to identify a character without depending on a code, character names are used. All JIS X 0208 graphic character codes are represented with two bytes of at least seven bits each. However, every control character, as well as the plain space – although not the ideographic space – is represented with a one-byte code. In order to represent the bit combination of a one-byte code, two decimal numbers – a column number and a line number – are used. Three high-order bits out of seven or four high-order bits out of eight, counting from zero to seven or from zero to fifteen form the column number.
Four low-order bits counting from zero to fifteen form the line number. Each decimal number corresponds to one hexadecimal digit. For example, the bit combination corresponding to the graphic character "space" is 010 0000 as a 7-bit number, 0010 0000 as an 8-bit number. In column/line notation, this is represented as 2/0. Other representations of the same single-byte code include 0x20 as hexadecimal, or 32 as a single decimal number; the double-byte codes are laid out in 94 numbered groups, each called a row. Every row contains 94 numbered codes, each called a cell; this makes a total of 8836 possible code points.
Chinese telegraph code
The Chinese telegraph code, Chinese telegraphic code, or Chinese commercial code is a four-digit decimal code for electrically telegraphing messages written with Chinese characters. A codebook is provided for decoding the Chinese telegraph code, it shows one-to-one correspondence between Chinese characters and four-digit numbers from 0000 to 9999. Chinese characters are arranged and numbered in dictionary order according to their radicals and strokes; each page of the book shows a number in a 10 × 10 table. The most significant two digits of a code matches the page number, the next digit matches the row number, the least significant digit matches the column number, with 1 being the column on the far right. For example, the code 0022 for the character 中, meaning “center,” is given in page 00, row 2, column 2 of the codebook, the code 2429 for the character 文, meaning “script,” is given in page 24, row 2, column 9; the PRC’s Standard Telegraph Codebook provides codes for 7,000 Chinese characters.
Senders convert their messages written with Chinese characters to a sequence of digits according to the codebook. For instance, the phrase 中文信息, meaning “information in Chinese,” is rendered into the code as 0022 2429 0207 1873, it is transmitted using the Morse code. Receivers decode the Morse code to get a sequence of digits, chop it into an array of quadruplets, decode them one by one referring to the book; the codebook defines codes for Zhuyin alphabet, Latin alphabet, Cyrillic alphabet, various symbols including special symbols for months, days in a month, hours. Senders may translate their messages into numbers by themselves, or pay a small charge to have them translated by a telegrapher. Chinese expert telegraphers used to remember several thousands of codes of the most frequent use; the Standard Telegraph Codebook gives alternative three-letter code for Chinese characters. It compresses telegram messages and cuts international fees by 25% as compared to the four-digit code. Looking up a character given a number is straightforward: page, column.
However, looking up a number given a character is more difficult, as it requires analyzing the character. The Four-Corner Method was developed in the 1920s to allow people to more look up characters by the shape, remains in use today as a Chinese input method for computers; the first telegraph code for Chinese was brought into use soon after the Great Northern Telegraph Company introduced telegraphy to China in 1871. Septime Auguste Viguier, a Frenchman and customs officer in Shanghai, published a codebook, succeeding Danish astronomer Hans Carl Frederik Christian Schjellerup’s earlier work. In consideration of the former code’s insufficiency and disorder of characters, Zheng Guanying compiled a new codebook in 1881, it remained in effect until the Ministry of Transportation and Communications printed a new book in 1929. In 1933, a supplement was added to the book. After the establishment of the People’s Republic of China in 1949, the codebook forked into two different versions, due to revisions made in the Mainland China and Taiwan independently from each other.
The Mainland version, the Standard Telegraph Codebook, adopted the simplified Chinese characters in 1983. The Chinese telegraph code can be used for a Chinese input method for computers. Ordinary computer users today hardly master it. However, the related Four-Corner Method, which allows one to look up characters by shape, is used; the Hong Kong residents’ identification cards have the Chinese telegraph code for the holder’s Chinese name. Business forms provided by the government and corporations in Hong Kong require filling out telegraph codes for Chinese names; the codes help inputting Chinese characters to a computer. Chinese telegraph code is used extensively in law enforcement investigations worldwide that involve ethnic Chinese subjects where variant phonetic spellings of Chinese names can create confusion. Dialectical differences and differing romanization systems can create serious problems for investigators, but can be remedied by application of Chinese telegraph code. For instance, investigators following a subject in Taiwan named Hsiao Ai-Kuo might not know this is the same person known in mainland China as Xiao Aiguo and Hong Kong as Siu Oi-Kwok until codes are checked for the actual Chinese characters to determine all match as CTC: 5618/1947/0948 for 萧爱国 / 蕭愛國.
Chinese telegraph code is used on occasion in U. S. and Australian Immigration documents. For example, the DS-230 form for K1/K2 visa applicants requires the telegraph code of the applicant's name. Code point Four-Corner Method, a 4-digit structural encoding method designed to aid lookup of telegraph codes Telegraph code Wiktionary page of Standard Telegraph Codebook, 1983 Baark, Erik. 1997. Lightning Wires: The Telegraph and China’s Technological Modernization, 1860–1890. Greenwood Press. ISBN 0-313-30011-9. Baark, Erik. 1999. “Wires and people: The Great Northern Telegraph Company in China.” In China and Denmark: Relations Since 1674, edited by Kjeld Erik Brødsgaard and Mads Kirkebæk, Nordic Institute of Asian Studies, pp. 119–152. ISBN 87-87062-71-2. Immigration Department of Hong Kong. 2006. Card fac
Cooke and Wheatstone telegraph
The Cooke and Wheatstone telegraph was an early electrical telegraph system dating from the 1830s invented by English inventor William Fothergill Cooke and English scientist Charles Wheatstone. It was a form of needle telegraph, the first telegraph system to be put into commercial service; the receiver consisted of a number of needles which could be moved by electromagnetic coils to point to letters on a board. This feature was liked by early users who were unwilling to learn codes, employers who did not want to invest in staff training. In systems the letter board was dispensed with, the code was read directly from the movement of the needles; this came about because the number of needles was reduced. The change was motivated by the economic need to reduce the number of telegraph wires used, related to the number of needles; the change became more urgent as the insulation of some of the early installations deteriorated, causing some of the original wires to be unusable. Cooke and Wheatstone's most successful system was a one-needle system that continued in service into the 1930s.
Cooke and Wheatstone's telegraph played a part in the apprehension of the murderer John Tawell. Once it was known that Tawell had boarded a train to London, the telegraph was used to signal ahead to the terminus at Paddington and have him arrested there; the novelty of this use of the telegraph in crime-fighting generated a great deal of publicity and led to increased acceptance and use of the telegraph by the public. The telegraph arose from a collaboration between William Fothergill Cooke and Charles Wheatstone, best known to schoolchildren from the eponymous Wheatstone bridge; this was not a happy collaboration due to the differing objectives of the two men. Cooke was an entrepreneur who wished to patent and commercially exploit his inventions. Wheatstone, on the other hand, was an academic with no interest in commercial ventures, he intended to publish his results and allow others to make use of them. This difference in outlook led to a bitter dispute between the two men over claims to priority for the invention.
Their differences were taken to arbitration with Marc Isambard Brunel acting for Cooke and John Frederic Daniell acting for Wheatstone. Cooke bought out Wheatstone's interest in exchange for royalties. Cooke had some ideas for building a telegraph prior to his partnership with Wheatstone and had consulted scientist Michael Faraday for expert advice. In 1836, Cooke built both an experimental electrometer system and a mechanical telegraph involving a clockwork mechanism with an electromagnetic detent. However, much of the scientific knowledge for the model put into practice came from Wheatstone. Cooke's earlier ideas were abandoned. In January 1837 Cooke proposed a design for a 60-code telegraph to the directors of the Liverpool and Manchester Railway; this was too complicated for their purposes. Rope-haulage into main stations was common at this time to avoid noise and pollution, in this case the gradient was too steep for the locomotive to ascend unaided. All, required were a few simple signals such as an indication to the engine house to start hauling.
Cooke was requested to build a simpler version with fewer codes, which he did by the end of April 1837. However, the railway decided to use instead a pneumatic telegraph equipped with whistles. Soon after this Cooke went into partnership with Wheatstone. In May 1837 Cooke and Wheatstone patented a telegraph system which used a number of needles on a board that could be moved to point to letters of the alphabet; the patent recommended a five-needle system, but any number of needles could be used depending on the number of characters it was required to code. A four-needle system was installed between Euston and Camden Town in London on a rail line being constructed by Robert Stephenson between London and Birmingham, it was demonstrated on 25 July 1837. This was a similar application to the Liverpool project; the carriages were travelled under gravity into Euston. A system was needed to signal to an engine house at Camden Town to start hauling the carriages back up the incline to the waiting locomotive.
As at Liverpool, the electric telegraph was in the end rejected in favour of a pneumatic system with whistles. Cooke and Wheatstone had their first commercial success with a telegraph installed on the Great Western Railway over the 13 miles from Paddington station to West Drayton in 1838. Indeed, this was the first commercial telegraph in the world; this was a six-wire system. The cables were installed underground in a steel conduit. However, the cables soon began to fail as a result of deteriorating insulation; as an interim measure, a two-needle system was used with three of the remaining working underground wires, which despite using only two needles had a greater number of codes. Since the new code had to be learned, not just read off the display, this was the first time in telegraph history that skilled telegraph operators were required; when the line was extended to Slough in 1843, a one-needle, two-wire system was installed. Cooke changed from running the cables in buried lead pipes to the less expensive and easier to maintain system of suspending uninsulated wires on poles from ceramic insulators, a system which he patented, which became the commonest method.
This extension was done at Cooke's own expense, as the railway company was unwilling to finance a system it still considered experimental