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60-720: (Redirected from DAH ) [REDACTED] Look up dah in Wiktionary, the free dictionary. Dah or DAH may refer to: Morse code symbol Dah, Ivory Coast , a village in Montagnes District Dah, Ladakh , a village in Jammu and Kashmir, India Dah, Mali , a town in Ségou Region Dah (band) , former Yugoslav/Belgian band Air Algérie (ICAO code: DAH), Algerian airline Gwahatike language ,

120-470: A dah is three times the duration of a dit (although some telegraphers deliberately exaggerate the length of a dah for clearer signalling). Each dit or dah within an encoded character is followed by a period of signal absence, called a space , equal to the dit duration. The letters of a word are separated by a space of duration equal to three dits , and words are separated by a space equal to seven dits . Morse code can be memorized and sent in

180-465: A PNG Finisterre language, ISO 639 code dah Dominica Award of Honour , an award of the Commonwealth of Dominica - postnominal letters are 'D.A.H.' See also [ edit ] Daha (disambiguation) Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Dah . If an internal link led you here, you may wish to change

240-462: A code became voiced as di . For example, the letter L (   ▄ ▄▄▄ ▄ ▄  ) is voiced as di dah di dit . Morse code was sometimes facetiously known as "iddy-umpty", a dit lampooned as "iddy" and a dah as "umpty", leading to the word " umpteen ". The Morse code, as specified in the current international standard, International Morse Code Recommendation , ITU-R  M.1677-1,

300-578: A code proficiency certification program that starts at 10  WPM . The relatively limited speed at which Morse code can be sent led to the development of an extensive number of abbreviations to speed communication. These include prosigns, Q 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). The abbreviations OM (old man), YL (young lady), and XYL ("ex-young lady" – wife) are common. YL or OM

360-416: A code system developed by Steinheil. A new codepoint was added for J since Gerke did not distinguish between I and J . Changes were also made to X , Y , and Z . This left only four codepoints identical to the original Morse code, namely E , H , K and N , and the latter two had their dahs extended to full length. The original American code being compared dates to 1838;

420-550: A codebook to look up each word according to the number which had been sent. However, the code was soon expanded by Alfred Vail in 1840 to include letters and special characters, so it could be used more generally. Vail estimated the frequency of use of letters in the English language by counting the movable type he found in the type-cases of a local newspaper in Morristown, New Jersey . The shorter marks were called "dots" and

480-407: A form perceptible to the human senses, e.g. via sound waves or visible light, such that it can be directly interpreted by persons trained in the skill. 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. The current or wave is present during the time period of the dit or dah and absent during

540-408: A method, an early forerunner to the modern International Morse code. 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

600-560: A slow data rate) than voice communication (roughly 2,400~2,800 Hz used by SSB voice ). Morse code is usually received as a high-pitched audio tone, so transmissions are easier to copy than voice through the noise on congested frequencies, and it can be used in very high noise / low signal environments. The fact that the transmitted power is concentrated into a very limited bandwidth makes it possible to use narrow receiver filters, which suppress or eliminate interference on nearby frequencies. The narrow signal bandwidth also takes advantage of

660-487: 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 dit durations versus 60 dit durations) and different interword gaps (5 dit durations versus 7 dit durations) may have been used when determining such speed records. For example, speeds run with

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720-404: A stylus onto the moving paper tape, making an indentation on the tape. When the current was interrupted, a spring retracted the stylus and that portion of the moving tape remained unmarked. Morse code was developed so that operators could translate the indentations marked on the paper tape into text messages. In his earliest design for a code, Morse had planned to transmit only numerals, and to use

780-517: A telegraph that printed the letters from a wheel of typefaces struck by a hammer. The American artist Samuel Morse , the American physicist Joseph Henry , and mechanical engineer Alfred Vail developed an electrical telegraph system. The simple "on or off" nature of its signals made it desirable to find a method of transmitting natural language using only electrical pulses and the silence between them. Around 1837, Morse therefore developed such

840-435: A way to communicate while maintaining radio silence . Automatic Transmitter Identification System (ATIS) uses Morse code to identify uplink sources of analog satellite transmissions. On-off keying On–off keying is most commonly used to transmit Morse code over radio frequencies (referred to as CW ( continuous wave ) operation), although in principle any digital encoding scheme may be used. OOK has been used in

900-427: Is a telecommunications method which encodes text characters as standardized sequences of two different signal durations, called dots and dashes , or dits and dahs . Morse code is named after Samuel Morse , one of the early developers of the system adopted for electrical telegraphy . International Morse code encodes the 26  basic Latin letters A to Z , one accented Latin letter ( É ),

960-471: 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

1020-570: Is most popular among amateur radio operators, in the mode commonly referred to as " continuous wave " or "CW". Other, faster keying methods are available in radio telegraphy, such as frequency-shift keying (FSK). The original amateur radio operators used Morse code exclusively since voice-capable radio transmitters did not become commonly available until around 1920. Until 2003, the International Telecommunication Union mandated Morse code proficiency as part of

1080-434: Is not to be used. 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. International Morse code today

1140-530: Is supposed to have higher readability for both robot and human decoders. Some programs like WinMorse have implemented the standard. 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. 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

1200-416: Is taught "like a language", with each code perceived as a whole "word" instead of a sequence of separate dots and dashes, such as might be shown on a page. With the advent of tones produced by radiotelegraph receivers, the operators began to vocalize a dot as dit , and a dash as dah , to reflect the sounds of Morse code they heard. To conform to normal sending speed, dits which are not the last element of

1260-413: Is used by an operator when referring to the other operator (regardless of their actual age), and XYL or OM (rather than the expected XYM ) is used by an operator when referring to his or her spouse. QTH is "transmitting location" (spoken "my Q.T.H." is "my location"). The use of abbreviations for common terms permits conversation even when the operators speak different languages. Although

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1320-694: 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 . 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

1380-777: The Spirit of St. Louis were off the ground, Lindbergh was truly incommunicado and alone. Morse code in aviation began regular use in the mid-1920s. By 1928, when the first airplane flight was made by the Southern Cross from California to Australia, one of its four crewmen was a 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 that transmitted continuous two- or three-letter identifiers in Morse code. Aeronautical charts show

1440-455: The Arabic numerals , and a small set of punctuation and procedural signals ( prosigns ). There is no distinction between upper and lower case letters. Each Morse code symbol is formed by a sequence of dits and dahs . The dit duration can vary for signal clarity and operator skill, but for any one message, once established it is the basic unit of time measurement in Morse code. The duration of

1500-770: The Double Plate Sounder System. 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 telegraph systems. In 1841, Cooke and Wheatstone built

1560-466: The ISM bands to transfer data between computers , for example. OOK is more spectrally efficient than frequency-shift keying , but more sensitive to noise when using a regenerative receiver or a poorly implemented superheterodyne receiver . For a given data rate, the bandwidth of a BPSK (Binary Phase Shift keying) signal and the bandwidth of OOK signal are equal. In addition to RF carrier waves, OOK

1620-700: 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. 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

1680-725: The prosign SK ("end of contact"). As of 2015 , the United States Air Force still trains ten people a year in Morse. 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 . However, the Federal Communications Commission still grants commercial radiotelegraph operator licenses to applicants who pass its code and written tests. Licensees have reactivated

1740-420: The spark gap system of transmission was dangerous and difficult to use, there had been some early attempts: In 1910, the U.S. Navy experimented with sending Morse from an airplane. However the first regular aviation radiotelegraphy was on airships , which had space to accommodate the large, heavy radio equipment then in use. The same year, 1910, a radio on the airship America was instrumental in coordinating

1800-701: 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 low , MF high , HF , VHF , and UHF . In some countries, certain portions of the amateur radio bands are reserved for transmission of Morse code signals only. Because Morse code transmissions employ an on-off keyed radio signal, it requires less complex equipment than other radio transmission modes . Morse code also uses less bandwidth (typically only 100–150  Hz wide, although only for

1860-532: The International code used everywhere else, including all ships at sea and sailing in North American waters. Morse's version became known as American Morse code or railroad code , and is now almost never used, with the possible exception of historical re-enactments. In aviation , pilots use radio navigation aids. To allow pilots to ensure that the stations they intend to use are serviceable,

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1920-630: 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 code-group 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 codes of one version or another have been in use for more than 160 years — longer than any other electrical message encoding system. What

1980-552: The United States from the Federal Communications Commission . Demonstration of this ability was still required for the privilege to use the shortwave 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, in the FCC reduced the Extra Class requirement to 5  WPM . Finally, effective on February 23, 2007,

2040-544: The amateur radio licensing procedure worldwide. However, the World Radiocommunication Conference of 2003 made the Morse code requirement for amateur radio licensing optional. Many countries subsequently removed the Morse requirement from their license requirements. 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

2100-543: The character that it represents in text of the English language. Thus the most common letter in English, the letter E , has the shortest code – a single dit . Because the Morse code elements are specified by proportion rather than specific time durations, the code is usually transmitted at the highest rate that the receiver is capable of decoding. Morse code transmission rate ( speed ) is specified in groups per minute , commonly referred to as words per minute . Early in

2160-565: The code. After some minor changes to the letters and a complete revision of the numerals, International Morse Code was standardized by the International Telegraphy Congress in 1865 in Paris, and later became the standard adopted by the International Telecommunication Union (ITU). Morse and Vail's final code specification, however, was only really used only for land-line telegraphy in the United States and Canada, with

2220-414: The facility may instead transmit the signal TEST (   ▄▄▄    ▄    ▄ ▄ ▄    ▄▄▄  ), or the identification 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

2280-612: The frequently used vowel O . Gerke changed many of the codepoints, in the process doing away with the different length dashes and different inter-element spaces of American Morse , leaving only two coding elements, the dot and the dash. Codes for German umlauted vowels and CH were introduced. Gerke's code was adopted in Germany and Austria in 1851. This finally led to the International Morse code in 1865. The International Morse code adopted most of Gerke's codepoints. The codes for O and P were taken from

2340-552: 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

2400-538: The identifier of each navigational aid next to its location on the map. In addition, rapidly moving field armies could not have fought effectively without radiotelegraphy; they moved more quickly than their communications services could put up new telegraph and telephone lines. This was seen especially in the blitzkrieg offensives of the Nazi German Wehrmacht in Poland , Belgium , France (in 1940),

2460-506: 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

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2520-409: The later American code shown in the table was developed in 1844. 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. Although previous transmitters were bulky and

2580-409: The link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Dah&oldid=1174878644 " Categories : Disambiguation pages Place name disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Morse code Morse code

2640-443: The longer ones "dashes", and the letters most commonly used were assigned the shortest sequences of dots and dashes. This code, first used in 1844, was what later became known as Morse landline code , American Morse code , or Railroad Morse , until the end of railroad telegraphy in the U.S. in the 1970s. In the original Morse telegraph system, the receiver's armature made a clicking noise as it moved in and out of position to mark

2700-505: The natural aural selectivity of the human brain, further enhancing weak signal readability. This efficiency makes CW extremely useful for DX (long distance) transmissions , as well as for low-power transmissions (commonly called " QRP operation ", from the Q-code for "reduce power"). There are several amateur clubs that require solid high speed copy, the highest of these has a standard of 60  WPM . The American Radio Relay League offers

2760-406: The needle and writing down the message. In Morse code, a deflection of the needle to the left corresponded to a dit and a deflection to the right to a dah . The needle clicked each time it moved to the right or left. By making the two clicks sound different (by installing one ivory and one metal stop), transmissions on the single needle device became audible as well as visible, which led in turn to

2820-422: 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 experimental designs were precursors to practical telegraphic applications. Following the discovery of electromagnetism by Hans Christian Ørsted in 1820 and

2880-494: The old California coastal Morse station KPH and regularly transmit from the site under either this call sign or as KSM. Similarly, a few U.S. museum ship stations are operated by Morse enthusiasts. 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 dits and dahs . Consequently, words also have different lengths in terms of dot duration, even when they contain

2940-472: 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

3000-408: The paper tape. Early telegraph operators soon learned that they could translate the clicks directly into dots and dashes, and write these down by hand, thus making the paper tape unnecessary. When Morse code was adapted to radio communication , the dots and dashes were sent as short and long tone pulses. Later telegraphy training found that people become more proficient at receiving Morse code when it

3060-527: The rescue of its crew. During World War I , Zeppelin airships equipped with radio were used for bombing and naval scouting, and ground-based radio direction finders were used for airship navigation. 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

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3120-538: The same number of characters. For this reason, some standard word is adopted for measuring operators' transmission speeds: Two such standard words in common use are PARIS and CODEX . 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

3180-688: 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, Theodore Roosevelt McElroy ( W1JYN ) set a still-standing record for Morse copying, 75.2  WPM . Pierpont (2004) also notes that some operators may have passed 100  WPM . By this time, they are "hearing" phrases and sentences rather than words. The fastest speed ever sent by

3240-546: 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 identified by " UCL ", and Morse code UCL is repeatedly transmitted on its radio frequency. In some countries, during periods of maintenance,

3300-462: The time between dits and dahs . Since many natural languages use more than the 26 letters of the Latin alphabet , Morse alphabets have been developed for those languages, largely by transliteration of existing codes. To increase the efficiency of transmission, Morse code was originally designed so that the duration of each symbol is approximately inverse to the frequency of occurrence of

3360-469: The traditional telegraph key (straight key) is still used by some amateurs, the use of mechanical semi-automatic keyers (informally called "bugs"), and of fully automatic electronic keyers (called "single paddle" and either "double-paddle" or "iambic" keys) is prevalent today. Software is also frequently employed to produce and decode Morse code radio signals. The ARRL has a readability standard for robot encoders called ARRL Farnsworth spacing that

3420-669: 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 . 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,

3480-435: 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 navies to scout for enemy warships, cargo ships, and troop ships. Morse code was used as an international standard for maritime distress until 1999 when it

3540-408: Was derived from a much-improved proposal by Friedrich Gerke in 1848 that became known as the "Hamburg alphabet", its only real defect being the use of an excessively long code (   ▄ ▄▄▄ ▄ ▄ ▄  and later the equal duration code   ▄▄▄ ▄▄▄ ▄▄▄  ) for

3600-549: Was replaced by the Global Maritime Distress and Safety System . When the French Navy ceased using Morse code on January 31, 1997, the final message transmitted was "Calling all. This is our last call before our eternal silence." 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

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