Morse code
The Morse code (also called Morse code or Morse code ) is a telegraphy technique for transmitting letters , numbers and other characters . A direct signal is switched on and off according to a characteristic time scheme .
The code can be transmitted as a sound signal , as a radio signal , as an electrical pulse with a Morse code key over a telephone line , mechanically or optically ( e.g. with a flashing light ) - or with any other medium with which two different states (such as sound or no sound ) can be displayed clearly and variable in terms of time. This transmission method is called Morse code.
The Morse code sometimes described in emergencies by knocking on metallic connections therefore only partially fulfills this requirement, but can be understood with a little practice due to the characteristic rhythm of Morse code. This hearing technology is derived from the "knockers" from the early days of telegraph technology , consisting of a powerful relay in an acoustic concave mirror, which made the sound of the Morse code audible even in larger operating rooms before the loudspeaker was invented.
history
Samuel Morse invented a simple electromagnetic write telegraph in 1837 . The code used at that time only comprised the ten digits; the transmitted numbers had to be translated into letters and words using a table.
Alfred Lewis Vail , a Morse employee, developed the first code from 1838, which also included letters. It consisted of characters of three different lengths and pauses of different lengths. This code was used operationally from 1844 (as the Morse Landline Code or American Morse Code on American railways and telegraph companies until the 1960s).
The pauses of different lengths represented an inadequacy of the code, so that Friedrich Clemens Gerke rewrote it in 1848 for the commissioning of the electromagnetic telegraph connection between Hamburg and Cuxhaven . After a few other small changes, this code was standardized at the International Telegraph Congress in Paris in 1865 and later standardized by the International Telecommunication Union (ITU) with the introduction of wireless telegraphy as the International Morse Code .
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A distress call was first mored over radio in 1909. This event led to the widespread introduction of maritime radio after the more conservative shipowners first rejected the new technology.
Morse code was replaced with the introduction of teleprinters from the telegraph networks. Due to its simplicity, it retained its importance in radio operations for a long time until it was gradually replaced by other methods. It still had a large field of application in maritime radio traffic until it lost its importance there with the introduction of the global distress and safety radio system (GMDSS) on February 1, 1999. The Morse code is still used in amateur radio (often referred to as the "CW" operating mode ), whereby in Germany knowledge of Morse was required until 2003 in order to participate in radio operations on shortwave frequencies below 30 MHz . The Morse code can also be found for teaching purposes with prospective telecommunications technicians .
Morse code are still used today in aviation and shipping to identify radio navigation systems (see radio beacons ). In addition to the actual navigation signal, these also send out an audible Morse code consisting of the three-letter identifier of the radio beacon. For example, the Barmen radio beacon sends its BAM ( - · · · · - - - ). Morse code is also still used in maritime shipping: radar beacons also respond with an echo to which their identifier is modulated in Morse code. The lighthouse in Kiel, for example, gives the acoustic signal KI every 30 seconds . Propagation beacons on Cubesat satellites typically also use Morse code.
In December 2014, the German Conference of Ministers of Education and Culture announced that Morse code would be included in the nationwide register of intangible cultural heritage in accordance with the UNESCO Convention on the Preservation of Intangible Cultural Heritage . In its justification, the German UNESCO Commission mentioned the special importance of radio amateurs , who uphold the rules and customs of Morse code and thus ensured that the forms and functions of the application remain alive.
International Morse Code
The Morse code uses only a simple continuous ( unmodulated ) signal as a basis . This means that it requires significantly less technical effort for sending and receiving than other forms of radio communication . It also works with a lot of interfering noises (with an unfavorable signal-to-noise ratio ), as you can clearly hear the unambiguous beat. Morse code requires only a small bandwidth and can therefore be inserted or filtered out even in overloaded radio bands. The simple on / off signals only require a low transmission power, even for long distances.
In the case of a radio signal that only consists of a carrier directly modulated with the Morse code ( A1A ), it is difficult to record Morse code in conventional amplitude modulation (AM) receivers because the Morse code hardly has any signal components in the audible range ; you have to use an SSB receiver set to a slightly offset frequency or switch on a beat oscillator (BFO) as a telegraph overlay in order to hear a clear tone.
Timing scheme and illustration
To visualize the code, dot ( ·) for the short tone, dash ( −) for long tone and space for pause in different widths (sometimes also commas or slashes for word separation) are used. The spoken syllables di (t) (dot) and dah (dash) are used for acoustic illustration and for learning and training purposes (for fluent pronunciation, di is common within characters and dit at the end of the character ). The word sequence Morse Code is z. B. written like this
M O R S E C O D E −− −−− ·−· ··· · −·−· −−− −·· ·
And as dahdah dahdahdah didahdit dididit dit, dahdidahdit dahdahdah dahdidit dit spoken.
The length of a diet determines the speed at which it can be sent. It is the basic unit of time to which all other times are traced back:
- A dah has a length of 3 dit .
- The length of the break is:
- 1 dit between two sent symbols,
- 3 Dit between letters in a word as well
- 7 Dit between words.
For the following example "MORSE CODE" this time signal results (here ="Signal on" and _"Signal off"):
===_===___===_===_===___=_===_=___=_=_=___=_______===_=_===_=___===_===_===___===_=_=___= ↑ ↑ ↑ ↑ ↑ Dah| | Di Wortabstand | Buchstabenabstand Symbolabstand
Standard code table
Here is a table showing the full alphabet and other common characters. There is no distinction between uppercase and lowercase letters in Morse code. The "zero" is crossed out in handwriting to distinguish it (like the symbol for average) to avoid confusion with the capital letter "O".
| Latin letters | Digits | Umlauts, ligatures, etc. Letters with diacritics |
Punctuation marks and special characters |
Signals (without Q groups ) |
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The choice of codes for the various characters is based on the frequency of letters in the English language (estimated by Alfred Vail) . Letters that appear more often should have a shorter code than less common ones in order to minimize the characters to be transmitted (see entropy coding ). The following table is well suited for decoding and shows the choice of codes based on the assumed frequency from left (often) to right (rarely).
| T - | M - - | O - - - | CH - - - - |
| Ö - - - · | |||
| G - - · | Q - - · - | ||
| Z - - · · | |||
| N - | K - · - | Y - - - | |
| C - - - | |||
| D - · · | X - · · - | ||
| B - · · · | |||
| E | A - | W - - | J - - - |
| P - - | |||
| R - | Ä · - · - | ||
| L · - · · | |||
| I · · | U · · - | Ü · - - | |
| F · · - · | |||
| S · · · | V · · · - | ||
| H · · · · |
SOS
In April 1904 at the German Imperial Navy , the Morse group three short, three long, three short · · · - - - · · · (as didididahdahdahdididit pronounced) introduced as a distress signal; With effect from April 1, 1905, it was also prescribed for public ship radio in Germany. This conspicuous Morse Code group was intended as an emergency signal to interrupt radio communication and, like a siren, was intended to call all other radio stations to radio silence. It was therefore not to be sent as a call, but to be repeated until all other stations had stopped transmitting. This should be followed by the content of the emergency call.
@-Character
The at sign (@), also called monkey tail or spider monkey , was added to the international Morse Code in May 2004 by the International Telecommunication Union (ITU), so that e-mail addresses can now also be morsed without unofficial detours . It is given as A followed by C without a pause ( · - - · - · ). This second update of the Morse code in about 40 years happened on the occasion of its 160th anniversary. In practice, however, the previous alternative, A followed by T, is still often used.
The first update of the Morse code was the necessary distinction between "open brackets" and "close brackets" (before that there was only "KK", ie - · - - · - ), which was introduced around 1960. As a result, the unofficial “KN” popular with radio amateurs officially got a different meaning.
Importance of short and long breaks
The opinion is sometimes expressed that the Morse code does not meet the Fano requirement . The coding for the letter E (“dit”) is also the beginning of the coding for the letters A (“di-dah”), F (“di-di-dah-dit”), etc. That would mean that the Morse code would be unusable because, for example, it would not be possible to distinguish whether the letter A or the character string ET was encoded.
However, Morse Code uses pauses of different lengths. The code of each character ends with a long pause, while the signals that belong to the code of a character are separated by short pauses. This allows the coding of the letter A (short signal, short pause, long signal, long pause) to be clearly distinguished from the coding of the character string ET (short signal, long pause, long signal, long pause). Because the code of each character ends with a long pause, but there are only short pauses within the code of one character, no code can be the beginning of another. So the Fano condition is met.
Sound samples
(20 words per minute, corresponds to 100 letters per minute), text and code:
AAA WIKIPEDIA DIE FREIE ENZYKLOPAEDIE AR
·- ·- ·- ·-- ·· -·- ·· ·--· · -·· ·· ·- -·· ·· · ··-· ·-· · ·· · · -· --·· -·-- -·- ·-·· --- ·--· ·- · -·· ·· · ·- ·-·
Speeds
Text: "Wikipedia the free encyclopedia". See also definition of speed .
| Letters per minute | Words per minute | Seconds | Sound sample |
|---|---|---|---|
| 40 | 8th | 42 | |
| 60 | 12 | 28 | |
| 80 | 16 | 21st | |
| 100 | 20th | 17th | |
| 120 | 24 | 14th |
The individual "handwriting"
Every radio operator has his own individual keystrokes and speeds at which he can be recognized by others - analogous to the uniqueness of handwriting. This fact took z. B. the Imperial Japanese Navy to outsmart the US communications intelligence in the attack on Pearl Harbor . The main radio operators of the main attacking warships were transferred and took up routine operations from other transmitters.
Transmission technology
Morse code is displayed optically (light Morse code) or acoustically (aural code or aural reading). When using light morse, u. a. the inertia of the light source or the eyes is a problem. A light bulb continues to glow after being switched off, so that the Morse code "blurs" at the end. When using Morse code with a rotating beacon (e.g. masthead light), a correspondingly slow transmission speed must be selected. To counteract this, Morse Code headlights with a screen in front of the light source were developed. The light source remains on all the time, but is darkened or opened accordingly by a locking mechanism. These closing flaps are also known as blinkers. The Morse code is no longer broadcast around, but only in a preferred direction.
Industrial engineering
The Morse code is used for the written record or display of texts which are transmitted in Morse Code. At the end of a letter there is a slash, at the end of a word two slashes, and at the end of a sentence three slashes are inserted. There are four slashes at the end of a paragraph.
Q groups
The use of so-called Q groups ( Q keys ) speeds up the transmission. This also enables international message transmissions without knowing the other language.
CQ
In the case of a general call, a "CQ" ( homonymous homophone for English seek you ) is given as an abbreviation instead of the call sign .
Call (example):
< cq cq cq de dl1xyz dl1xyz dl1xyz pse k < Bedeutung: Allgemeiner Anruf von dl1xyz – bitte kommen …
Transfer rate
The transmission rate with Morse code is measured in letters per minute (BpM) or in words per minute (WpM), whereby one “word” corresponds to 5 letters. Counting in "words" has its origins in the habit of grouping the endless columns of letters of ciphered military texts in groups of 5 letters, the so-called groups of five, for better legibility. The question of BpM or WpM is purely a matter of taste, but there is a kind of habit: radio amateurs in Europe z. B. usually use BpM, which in the US use WpM.
Since not all letters are the same length and therefore take different lengths in Morse code, the specification BpM alone would be very imprecise. The word PARIS was therefore selected as a reference for speed measurement. Both short and long letters appear in it. The word PARIS ( · - - · · - · - · · · · · · ) therefore forms an average value in the time it takes for transmission. If you give the word PARIS with its 5 letters 12 times in one minute, the speed is 60 bpm.
The word PARIS (including the following word gap) has a length of 50 dits (see above, example: the E consists of two dits: period + pause). The higher the transfer rate, the shorter the dits. 1 WpM corresponds to 50 dits per minute, therefore:
| Transfer rate [WpM] |
Length of a dit [ms] |
≈ BpM |
|---|---|---|
| 1 | 1200 | 5 |
| 5 | 240 | 25th |
| 12 | 100 | 60 |
| 20th | 60 | 100 |
| 50 | 24 | 250 |
Beginners can hardly get beyond 5 WpM. This is because letters and characters are not perceived as a unit - comparable to a novice reader who struggles to understand the meanings of words through the sound of individual letters.
The test speed for radio amateurs was 12 WpM. With a lot of practice you can exceed the 20 WpM mark, very good radio operators achieve over 50 WpM. The world record for Morse code (transcribing letters in groups of five) is 88 WpM (440 letters per minute), see fast telegraph .
When using light Morse code (i.e. when using Morse code with light signals) z. For example, between two ships at sea, the transmission speed is around 8 WpM (40 BpM), with signals "Blinkis" from the German Navy. For comparison: a newscaster transmits 100 to 200 words per minute, an ISDN data line approx. 50,000 words per minute.
Learn to recognize Morse code
Koch method
One of the most effective training techniques that has been developed was published and used in 1936 by the German psychologist Ludwig Koch . The basic principle is based on the formation of reflexes. You learn the Morse code directly at high speed (with at least 20 WpM, at the beginning with a longer distance between the characters, i.e. effectively 15 WpM). This prevents the involuntary formation of translation tables in the brain. In addition, Morse code given more slowly sound musically very different from Morse code given quickly. At the beginning, two characters are selected that do not sound similar, e.g. B. K and M, which you write down for five minutes. If you have written 90 percent of the two characters correctly, you have already learned them permanently and at top speed and then add the third character.
Recognition (decoding) of Morse code
In the past, an alphabetical listing of letters, digits and special characters was used to learn Morse code for beginners (like the standard code table shown above). From this, he had to take the dot-dash sequences (signal sequences) that he had to "give". Morse code words were used as an aid to facilitate learning in the initial phase.
In addition, there was the opposite way, namely the recognition of the Morse code. This recognition is a decoding of the Morse code, it is not a problem for radio operators and light marshals, because they hear or see and recognize the transmitted Morse code automatically, it has become their flesh and blood. You have practiced and learned to “hear” and “see”.
However, the beginner needed an inverse Morse code table to decode the signal sequence of a transmitted character. The alphabetically arranged table shown above is not suitable for this, because the entire alphabet must be searched for every Morse code to see whether the signal sequence you are looking for is there and to which Morse code it belongs.
The Morse code table shown in the picture on the right is arranged inversely according to signal sequences. It consists of two binary trees , one with the root “dot” and the other with the root “dash”. These two roots are in the upper left corner of the Morse board. The respective tree branches out over 6 to 8 levels, with the name of the Morse code at the nodes, which extends from the root to this node.
When decoding, you started from the respective root (dot or dash) at the top left and followed the branches until the Morse code was "processed". The name (letter, number, special character) is then at the node.
The alternative Wernicke Morse Table also has a representation based on nodes. This differs in the structural grouping of letters, numbers, umlauts, ligatures, diacriticals and special characters as well as signals.
Others
Knocking Morse
In the early days of telegraphy, before loudspeakers and sinusoidal tone generators were used, or when the lines for sound transmission were too long - amplifiers were still unknown - the characters were identified solely by moving coil deflections when the contacts were closed or opened, or by “knockers”, relays if there was enough current flow on a sounding plate, made audible. Two clicks in quick succession stand for a point, longer apart clicks for a line. This knocking or cracking technique was rare and was used, for example, in American telegraphy and in the first attempts with the transatlantic line. The last known uses of the technique were in US Navy survival training programs. This method of transmitting letters with pure knock signals, known as the knock code , is used among prisoners in the prison environment. It is called Kasper in the crooks language .
Morse code in the film
Morse code is often used in many (cinema) films to represent “secret” communication. However, there is usually no connection between the audible characters and the content that the actors read from the characters: A few Morse letters sometimes create longer messages that contain many words and sentences. Often in the film, messages are sent via Morse code as a knock signal (for example from cell to cell in prison). You cannot knock "long" or "short", in this case the pause between the individual knock signals counts (see " Knock Morse "). Different knocking noises would also be a possibility or even an alphabet of knocking characters ( e.g. Polybios cipher ).
Morse code on television and radio
Some television shows used Morse signals, often as jingles , embedded in music. In the news broadcast today in the ZDF the Morse code for the word "today" is used ( · · · · · · · - - · ). After the ARD - Tagesschau the weather report with the Q-group “QAM” ( - - · - · - - - ) for “weather report” was ended. The theme music from ARD-Brennpunkt was also backed by the Morse code for "Brennpunkt". The West German Broadcasting (WDR) used as a prefix of the radio program, the gemorste word "time signal" over a long period time signal . The radio program RADIO 700 has been using the “QAM” signal at the end of the weather report since 2008 and the SWR1 Rhineland-Palatinate station of Südwestrundfunk , interspersed in the background, has been used again since 2009 to mark the weather report.
A well-known use of a Morse code was the use of the letter V ( · · · - ) as a symbol for “Victory” by the BBC during World War II. This was later interpreted as a tribute to the very similar sounding rhythm of the head motif of the first movement of Beethoven's 5th Symphony , but was not originally intended.
Morse code and music
Musicians have also discovered Morse code for themselves and thus hide messages in their pieces, for example Kraftwerk . Further examples are the title Lucifer from The Alan Parsons Project or the song In the Name of God by Dream Theater , whose hidden Morse code was only discovered several months after the CD was released. A popular example is the song YYZ by Rush , in which the associated Morse code runs through the song as a rhythm. On the album Amarok by the musician Mike Oldfield there is a morphed “farewell” to the owner of his previous record company: “ Fuck off RB”. With RB Richard Branson , the owner of Virgin Records , is meant. In his piece Communication , the jazz musician Slim Gaillard mores the general call "CQ" in the chorus.
Morse code in science fiction literature
In many scenarios of future literature , the end of the world threatens , which a hero tries to stop. In some cases, he receives secret or coded warnings that come from the future, for example in the science fiction thriller The Tomorrow Code , in which two New Zealand teenagers receive warnings from the future that are encrypted using Morse code.
Morse code vs. SMS
In the NBC television series The Tonight Show with Jay Leno on May 13, 2005, there was a little competition to determine whether SMS -Input or Morse code is faster. Here, two young people competed against two radio amateurs. The two radio amateurs, who had been working on it for 38 and 43 years respectively, were faster than the youngsters.
Morse code and cell phone ringtones
A well-known Morse ringtone is the SMS tone “Special” used by Nokia (in phonetic spelling “dididit dahdah dididit”), which - according to its purpose - symbolizes the sequence of letters SMS. This should not be confused with the Morse code for SOS (“didididahdahdahdididit”). Another Morse ringtone (also from Nokia) is "connecting people" as an alarm clock signal.
Traces on Mars
The Mars rover Curiosity - built by the Jet Propulsion Laboratory (JPL) - rolls on tires whose profile presses the Morse code for J, P and L into the ground. The tire tracks are used to recognize the locomotion, especially on the optically rather monotonous ground without these tire marks. The orientation of the vehicle and the extent to which tires are slipping can be identified from the lane, with the aim of making driving more efficient.
Morse code and navigation marks
In seafaring, there are navigation signs that emit Morse code in the form of light signals. For example, a barrel with the designation “Mo (A) 8s” mores the character “A” with a return of 8 seconds.
There are also radar word beacons that morse code letters in response to a received radar signal.
Morse code in aviation
Morse code is used for radio beacons in aviation. Morse code can be found, for example, in the dying NDB (non-directional radio beacon) and the currently more important VOR (rotary radio beacon). The NDB or VOR source is selected based on the frequency and verified using the Morse code. Usually the code is 3 letters long. The pilot can switch the received signal to his headphones at the receiver for eavesdropping.
Morse code and telephone
The older di-dah ( · - ) for the dial tone represents the Morse code "a" for office.
literature
- William G. Pierpont (N0HFF): The Art of Radiotelegraphy - A Guide to Learning, Using, Mastering and Enjoying International Morse Code as a Communication Tool . (PDF; 3.7 MB) 3rd revised. Edition. July 19, 2001, from the American by Olaf Rettkowski, DL9AI, May 17, 2007, original title: The Art and Skill of Radio-Telegraphy. - This book can be distributed freely (see preface) and is available in several languages.
- Rudolf Grötsch: Correct Morse Code - A Guide for Morse Instruction. 11th ext. Edition. Jakob Schneider Verlag, Berlin-Tempelhof 1964.
- High Command of the Wehrmacht : regulation H.Dv. 426, L.Dv. 407 - Instructions for training in Morse code. 1941.
- Wolfgang Buddrus: They were radio operators: memories of a past job. 3. Edition. Books on Demand , 2014, ISBN 978-3-7322-7235-8 .
Web links
- Recommendation ITU-R M.1677-1. (PDF; 1.4 MB) Specification of the Morse code
- AGCW-DL e. V. - Telegraphy Working Group
- Text to Morse & Morse to Text Converter
- Coding and decoding of Morse text in different spellings
- CW player for receiving, sending and learning
Individual evidence
- ↑ Ralf Klee, Broder-Jürgen Trede: 100 years of distress call: Morse code until the sinking. one day , January 23, 2009; Retrieved January 25, 2017.
- ↑ Virginia Lovelace: January 23rd, 1909 - The day when Jack Binns became the first hero of wireless acclaimed throughout the world for his efforts during a daring rescue at sea. To Jack Binns - Wireless Hero. Online at JackBinns.org, accessed January 25, 2017.
- ↑ Award of 27 cultural forms as intangible cultural heritage in Germany - the cooperative idea will be nominated by UNESCO at the end of March. (PDF; 93 kB) Press release of the Conference of Ministers of Education, March 16, 2015, on KMK.org; Retrieved January 25, 2017.
- ↑ Morse code. German UNESCO Commission, year of admission 2014, UNESCO.de; Retrieved January 25, 2017.
- ^ RW Burns: Communications: an international history of the formative years. Institution of Electrical Engineers, London 2004, ISBN 0-86341-327-7 , p. 84.
- ^ Regulations for the use of spark telegraphy in public transport, Official Gazette of the Reichs-Postamt, Berlin, March 30, 1905.
- ↑ Update for the Morse alphabet . heise online
- ^ Morse Code Enters The 21st Century . slashdot.org
- ^ The publications by Ludwig Koch can be found on a CD from the AGCW-DL . AGCW-DL Arbeitsgemeinschaft Telegrafie e. V.
- ^ Wernicke Morse Table. Wernicke Morse Table
- ↑ DK5KE - Morse code
- ^ David B. Dennis: Beethoven in German Politics, 1870-1989. Yale University Press, New Haven 1996, ISBN 0-300-06399-7 , pp. 170 f., Limited preview in Google Book Search, accessed on December 24, 2016.
- ↑ Ludwig Szopinski (DK5KE): Morse code without funk - a special stylistic device in music. In: DK5KE Morse code - music with Morse code. Online at QSL.net, accessed December 24, 2016.
- ^ SMS vs Morse. Video on metacafe.com (95 seconds), accessed on December 24, 2016.
- ↑ Nokia tones from Morse codes
- ↑ The last hurray for NASA. ORF press report, August 15, 2012, online at ORF.at, accessed on January 14, 2017.
- ↑ Christoph Seidler: Mars vehicle "Curiosity": powerful hum on the approach. In: Spiegel. August 3, 2012, online at Spiegel.de, accessed on January 14, 2017.
- ↑ Rover Leaves Tracks in Morse Code jpl.nasa.gov, News, August 29, 2012, accessed December 9, 2018.