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Morse code

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Portrait of Samuel F. B. Morse.Image provided by Classroom Clip Art (http://classroomclipart.com)
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Portrait of Samuel F. B. Morse.Image provided by Classroom Clip Art (http://classroomclipart.com)

Morse code is a method for transmitting information, using standardized sequences of short and long marks or pulses — commonly known as "dots" and "dashes" — for the letters, numerals and special characters of a message. Originally created for Samuel Morse's electric telegraph in the mid-1830s, it was also extensively used for early radio communication beginning in the 1890s. However, with the development of more advanced communications technologies, the use of Morse code is now largely obsolete, although it is still employed for a few specialized purposes, including navigational radio beacons, and by CW (continuous wave) amateur radio operators. Morse code is the only digital modulation mode designed to be easily read by humans without a computer, making it appropriate for sending automated digital data in voice channels.

Morse code can be transmitted in a number of ways: originally as electrical pulses along a telegraph wire, but also as an audio tone, as a radio signal with short and long pulses or tones, or as a mechanical or visual signal (e.g. a flashing light). Because Morse code is transmitted using just two states — on and off — it was an early form of a digital code. International Morse code is composed of six elements:

  1. short mark, dot or 'dit' (·)
  2. longer mark, dash or 'dah' (-)
  3. intra-character gap (between the dots and dashes within a character)
  4. short gap (between letters)
  5. medium gap (between words)
  6. long gap (between sentences)

However, the variable length of the Morse characters made it hard to adapt to automated communication, so it was largely replaced by more regular formats, including the Baudot code and ASCII.

What is called Morse code today actually differs somewhat from what was originally developed by Morse and his assistant, Alfred Vail. In 1848 a refinement of the code sequences, including changes to eleven of the letters, was developed in Germany and eventually adopted as the worldwide standard as "International Morse". Morse's original code specification, largely limited to use in the United States, became known as Railroad or American Morse code, and is now very rarely used.

Contents

Development

Beginning in the mid-1830s, Samuel Morse and Alfred Vail developed an electric telegraph, which used electrical currents to control an electromagnet that was located at the receiving end of the transmission wire. The technological limits of the time made it impossible to print individual characters in a readable form, so the inventors had to devise an alternate method of communication. Beginning in 1837, William Cooke and Charles Wheatstone operated electric telegraphs in England, which also controlled electromagnets in the receivers, however, in their systems needle pointers were rotated in order to indicate the characters being sent. In contrast, Morse and Vail's initial telegraph system, which first went into operation in 1844, marked a paper tape — when an electrical current was transmitted, the receiver's electromagnet rotated an armature, so that it began to scratch a moving tape, and when the current was removed the receiver retracted the armature, so that portion of the tape was left unmarked.

The Morse code was developed so that operators could translate the indentions marked on the paper tape into text messages. Initially, Morse had planned to only transmit numerals, and use a dictionary to look up each word according to the number which had been sent. However, the code was expanded to include letters and special characters, so it could be used for more complete messages. The shorter marks were called "dots", and the longer ones "dashes", and the letters most commonly used in the English language were assigned the shortest sequences.

In the original Morse telegraphs, the receiver's armature made a clicking noise as it moved into and out of position for marking the tape. Operators soon learned to directly read the clicks as the beginning and end of dots and dashes, meaning that it was no longer necessary to use the tape.

When Morse code was adopted to radio, the dots and dashes were normally sent as short and long tones. It was later found that people become more proficient at receiving Morse code when is taught as a language that is heard, instead of one read from a page[1] (http://www.arrl.org/FandES/ead/learncw/)[2] (http://www.1728.com/morstest.htm)[3] (http://www.arsqrp.com/ars/pages/back_issues/2000_text/1200_text/morse.html). To reflect the sound of Morse code, practitioners vocalise a dash as "dah", and a dot as "dit". When a dit is not the final element of a character, its sound is shortened to "di-" to maintain a better vocal rhythm.

Morse messages are generally transmitted by a hand-operated device such as a telegraph key, so there are variations introduced by the skill of the sender and receiver — more experienced operators can send and receive at faster speeds. In general, any code representing written symbols as variable length signals can be called a Morse code, but the term is used specifically for the two kinds of Morse code used for the English alphabet and associated symbols.

Telegraph companies charged based on the length of the message sent. Elaborate commercial codes were developed that encoded common phrases in five-letter groups that were sent as single words. Examples: BYOXO ("Are you trying to crawl out of it?"), LIOUY ("Why do you not answer my question?"), and AYYLU ("Not clearly coded, repeat more clearly."). The letters of these five-letter code words were sent individually using Morse code. In computer networking terminology one would say the commercial code is layered on top of Morse code, which in turn is layered on top of binary code, which in turn is layered on top of a physical telegraph wire. Still in use in Amateur Radio are the Q code and Z code; they were and are used by the operators themselves for service information like link quality, frequency changes, and telegram numbering.

When considered as a standard for information encoding, Morse code had a successful lifespan that has not yet been surpassed by any other electronic encoding scheme. Morse code was used as an international standard for maritime communication until 1999 when it was replaced by the Global Maritime Distress Safety System. When the French navy ceased using Morse code in 1997, the final message transmitted was "Calling all. This is our last cry before our eternal silence." See also: international distress frequency

Recently a few widely publicized speed contests have been held between expert Morse code operators and expert cellphone SMS text messaging users (see external links). Morse code has consistently won the contests, leading to speculation that cellphone manufacturers may eventually build a Morse code interface into cellphones. The interface would automatically translate the Morse code input into text so that it could be sent to any SMS capable cellphone so therefore the receiver of the message need not know Morse code to read it. Other speculated applications include taking an existing assistive application of Morse code and using the vibrating alert feature on the cellphone to translate SMS messages to Morse code for silent, hands free "reading" of the incoming messages. Several cellphones already have informative audible Morse code ring tones and alert messages, for example: many Nokia cellphones have an option to beep SMS in Morse code when it receives an SMS text message. These kinds of innovations could lead to a Morse code revival. There are third party applications already available for some cellphones that allow Morse code input for sending SMS (see external links).

Modern International Morse code

The Modern International Morse code was invented by Friedrich Clemens Gerke in 1848 and used for the telegraphy between Hamburg and Cuxhaven in Germany. After some minor changes in 1865 it has been standardised at the International Telegraphy congress in Paris (1865), and later normed by the ITU as International Morse code.

International Morse code is still in use today, although it has become almost exclusively the province of amateur radio operators. Until 2003 the International Telecommunications Union (ITU) mandated Morse code proficiency as part of the amateur radio licensing procedure throughout the world. In some countries, certain parts of the amateur radio bands are still reserved for transmission of Morse code signals only.

Since Morse relies on only an (on-off keyed) radio signal, it requires less complex equipment than other forms of radio communication, and it can be used in very high noise / low signal environments. It also requires less bandwidth than voice communications, typically 100-150 Hz, compared to the roughly 4000 Hz of single-sideband voice. The extensive use of pro-signs, Q codes, and restricted format of typical messages facilitates communication between amateur radio operators who do not share a common mother tongue and would have great difficulty in communicating using voice modes.

Morse code is also very popular among QRP operators for enabling very long distance, low-power communication. Readability can be sustained by trained operators even though the signal is only faintly readable. This level of "penetration" is due to the fact that all transmitted energy is concentrated in a very small bandwidth making the use of a narrow receiver bandwidth practical. A narrow bandwidth receiver uses filters to exclude interference on frequencies close to the desired frequency. Concentrating the transmitted energy in a small bandwidth gives the signal a "spectral brightness" that is much higher than the average natural noise (but see also spread spectrum).

In the United States until 1991, a demonstration of the ability to send and receive Morse code at 5 words per minute (WPM) was required to receive an FCC amateur radio license. Demonstration of this ability is still required for the privilege to use the HF bands. Until 2000, proficiency at the 20 WPM level was required to receive the highest level of amateur license (Extra Class); effective April 15, 2000, the FCC reduced the Extra Class requirement to 5 WPM.Template:Ref

The World Radiocommunication Conference of 2003 (WRC-03) made optional the international Morse code requirement for amateur radio licensing. In July, 2005, the Federal Communications Commission published a Notice of Proposed Rulemaking that, if made a permanent FCC Rule, would eliminate all Morse code testing for Amateur Radio licensees. As with all informal rulemaking under the Administrative Procedures Act, it will take time for the Rule to go into effect, as a long Comment period must be observed. Most expect the period of Comment and debate to be contentious, as many amateur operators believe eliminating code testing to be detrimental and contrary to the heritage of radio, while others strongly hold that requiring code is outdated, and keeps new blood out of the hobby.

Amateur and military radio operators skilled in Morse code can often understand ("copy") code in their heads at rates in excess of 40 WPM. Although the traditional telegraph key (straight key)is still used by many amateurs, the use of semi- and fully-automatic electronic keyers (known as "bugs") is prevalent today. Computer software is also frequently employed to produce and decode Morse code RF signals.

A commercially manufactured iambic paddle used in conjunction with an electronic keyer to generate high-speed Morse code.
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A commercially manufactured iambic paddle used in conjunction with an electronic keyer to generate high-speed Morse code.

As of 2004 commercial radiotelegraph licenses are still being issued in the United States by the Federal Communications Commission. Designed for shipboard and coast station operators, they are awarded to applicants who pass written examinations on advanced radio theory and show 20 WPM code proficiency (this requirement is waived for "old" Extra Class licensees). However, since 1999 the use of satellite and very high frequency maritime communications systems (GMDSS) have essentially made them obsolete.

On May 24 2004, the 160th anniversary of the first telegraphic transmission, the ITU added the "@" (the "commercial at" or "commat") character to the Morse character set and is the digraph "AC" (probably to represent "A[T] C[OMMERCIAL]" or the letter "a" inside the swirl appearing to be a "C").Template:Ref The new character facilitates sending electronic mail addresses by Morse code and is notable since it is the first official addition to the Morse set of characters since World War I.

Morse code as an assistive technology

Morse code has a 21st century role as an assistive technology, helping people with a variety of disabilities to communicate. Morse can be sent by someone with severe motion disability, as long as they have some minimal motor control. In some cases this means alternately blowing into and sucking on a plastic tube ("puff and sip" interface). People with severe motion disabilities in addition to sensory disabilities (e.g. people who are deaf and/or blind, and have severe motion disabilities) can receive Morse through a skin buzzer. Products are available that allow a computer operating system to be controlled by Morse code, allowing the user access to the Internet and electronic mail. See: Morse2000 assistive communications siteTemplate:Ref

Representation and timing

There are two "symbols" used to represent letters, called dots and dashes or (more commonly among CW users) dits and dahs. The length of the dit determines the speed at which the message is sent, and is used as the timing reference. Here is an illustration of the timing conventions. Its intent is to show exact timing — it would normally be written something like this:

-- --- ·-· ··· ·   /      -·-· --- -·· ·
M  O   R   S   E  (space) C    O   D   E

where - represents dah and · represents dit. Here's the exact conventional timing for the same message (= represents signal on, . represents signal off, each for the length of a dit):

===.===...===.===.===...=.===.=...=.=.=...=.......===.=.===.=...===.===.===...===.=.=...=
   ^              ^     ^     ^               ^               ^
   |              dah   di    dit             |               |
   symbol space                               word space      letter space

In text-book, full-speed Morse, a dah is conventionally 3 times as long as a dit. Spacing between dits and dahs in a character is the length of one dit. Spacing between letters in a word is the length of a dah (3 dits). Spacing between words is 7 dits.

Those learning Morse are often taught to send and understand letters and other symbols at their full target speed, that is with normal relative timing of the dots, dashes and spaces within each symbol for that speed. Exaggerated spaces between symbols and words are used to give 'thinking time', which can be reduced with practice and familiarity. This makes the sound 'shape' of the letters and symbols easier to learn. This teaching method is referred to as the Farnsworth method.

Morse code is often spoken or written as follows:

-- --- ·-· ··· · / -·-· --- -·· ·

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

Note that there is little point in learning to read written Morse as above, rather the sounds of all of the letters and symbols need to be learned, both to send and to receive.

The speed of Morse code is typically specified in "words per minute" (WPM). The Paris standard defines the speed of Morse transmission as the dot and dash timing needed to send the word "Paris" a given number of times per minute. The word Paris is chosen because it is precisely 50 "dits" based on the text book timing.

It has been claimed that musicians learn the rhythms of the Morse code characters faster than non-musicians. Conversely, Morse code has been used in music, both as a source for rhythmic patterns and as recorded samples, such as Vladimir Ussachevsky's Wireless Fantasy and in the Rock band Rush's song YYZ, based on the Morse code for Toronto's Pearson International Airport's IATA code. The theme tune to the BBC's television series Inspector Morse is another example.

Letters, numbers, punctuation, prosigns

|}

Common punctuation

International code
Period [.] ·-·-·-
Comma [,] --··--
Question mark [?] ··--··
Apostrophe ['] ·----·
Exclamation mark [!] -·-·--
Slash [/] -··-·
Parentheses ( ) -·--·-
Ampersand [&] · ···
Colon [:] ---···
Semicolon [;] -·-·-·
Double dash [=] -···-
Fraction bar -··-·
Hyphen [-] -····-
Underscore [_] ··-- ·-
Quotation mark ["] ·-··-·
At sign [@] ·--·-·

The "@" symbol was added in 2004, and combines A and C into one character.

Special symbols (prosigns)

Prosigns or procedural signals are dot/dash sequences that have a special meaning. They can often be viewed as if they were composed of one, two or three Morse code alphabetic characters. When composed in this way of more than one character, they are sent "run together"; that is, omitting the normal pauses that would occur if they were being sent as letters of text. These ligatures are normally represented in print by the letters with a ligating bar above them.

Prosigns
Sign Code MeaningComment
<math>\overline{\mbox{AR}}<math>·-·-·Stop (end of message)Often written +
<math>\overline{\mbox{AS}}<math>·-···Wait (for 10 seconds)Respond with C (yes). AS2 means wait 2 min, AS5 5 min, etc. For pauses of 10 min or longer, use QRX (see Q code)
<math>\overline{\mbox{BT}}<math>-···-Separator within messageOften written =. In practice, indistinguishable from <math>\overline{\mbox{TV}}<math>, and sometimes written thus
<math>\overline{\mbox{CL}}<math>-·-··-··Going off the air"Clear"
<math>\overline{\mbox{DO}}<math>-··---Shift to wabun code
<math>\overline{\mbox{K}}<math>-·-General invitation to transmitOften sent after CQ
<math>\overline{\mbox{KN}}<math>-·--·Specific invitation to transmitOften indicates "back-to-you"
<math>\overline{\mbox{R}}<math>·-·Received and understood"Roger"
<math>\overline{\mbox{SK}}<math>···-·-End (end of contact)In practice, indistinguishable from <math>\overline{\mbox{VA}}<math>, and sometimes written thus
<math>\overline{\mbox{SOS}}<math>···---··· Serious distress message and request for urgent assistance (Template:Audio-nohelp)Not to be used unless there is imminent danger to life or to a vessel at sea. See SOS

Although these are not really prosigns, an error may be indicated by some series of <math>\overline{\mbox{E}}<math>s:

······· Error, correct word follows (six or more dots in a row)
· · · Error (easily identifiable by "broken" rhythm)

Non-English extensions to the Morse code

ä ·-·- (also æ)
à ·--·- (also å)
ĉ -·-·· (also ç)
ch ----
ð ··--·
è ·-··-
é ··-··
ĝ --·-·
ĥ -·--·
ĵ ·---·
ñ --·--
ö ---· (also ø)
ŝ ···-·
þ ·--··
ü ··-- (also ŭ)
" ·-··-·

Alternate display of more common characters for the international code

Some methods of teaching or learning morse code use the dichotomic search table below.

In order to understand the table, consider the second row: ·· is 'I'; ·- is 'A'; -· is 'N'; and -- is 'M'. You can follow a pattern of dots and dashes from the top and move left for dot and right for dash until the letter is complete.

dot dash
E T
I A N M
S U R W D K G O
H V F Ü L Ä P J B X C Y Z Q Ö CH
5 4 Ŝ 3 É Ð 2 È + Þ À Ĵ 1 6 = / Ĉ Ĥ 7 Ĝ Ñ 8 9 0
 ? _ " . @ ' -  ;  ! ( ) ,  :

Commonly-used Morse code abbreviations

Abbreviations differ from prosigns in that they observe normal interletter spacing; that is, they are not "run together" the way prosigns are.

AA All after (used after question mark to request a repetition)
AB All before (similarly)
ARRL American Radio Relay League
ABT About
ADS Address
AGN Again
ANT Antenna
BN All between
BK Break (to pause transmission of a message, say)
BUG Semiautomatic mechanical key
C Yes
CBA Callbook address
CFM Confirm
CLG Calling
CQ Calling any station
CQD Original International Distress Call
CS Callsign
CUL See you later
CUZ Because
CW Continuous wave
CX Conditions
DE From
DSW Goodbye (Russian: Dosvidanya)
DX Distance (sometimes refers to long distance contact)
ES And
FB Fine business (Analogous to "OK")
FCC Federal Communications Commission
FER For
FM From
FREQ Frequency
GA Good afternoon or Go ahead (depending on context)
GE Good evening
GM Good morning
GND Ground (ground potential)
GUD Good
HIHI Laughter
HR Here
HV Have
LID Poor operator
MILS Milliamperes
NIL Nothing
NR Number
OB Old boy
OC Old chap
OM Old man (any male amateur radio operator is an OM)
OO Official observer
OP Operator
OT Old timer
OTC Old timers club
OOTC Old old timers club
PSE Please
PWR Power
QCWA Quarter Century Wireless Association
R I acknowledge or decimal point (depending on context. The origin of "Roger")
RCVR Receiver
RIG Radio apparatus
RPT Repeat or report (depending on context)
RPRT Report
RST Signal report format (Readability-Signal Strength-Tone)
RTTY Radioteletype
RX Receive
SAE Self-addressed envelope
SASE Self-addressed, stamped envelope
SED Said
SEZ Says
SIG Signal or signature
SIGS Signals
SKED Schedule
SN Soon
SMS Short message service
SRI Sorry
STN Station
TEMP Temperature
TMW Tomorrow
TNX Thanks
TU Thank you
TX Transmit, transmitter
U You
UR Your or You're (depending on context)
URS Yours
VY Very
W Watts
WDS Words
WKD Worked
WL Will
WUD Would
WX Weather
XMTR Transmitter
XYL Wife
YL Young lady (used for any female)
73 Best regards
88 Love and kisses

See also: Q code. These abbreviations are used in conjuction with the Q codes common to amateur radio.

Conversation in Morse code

The skill to have sensible conversations with Morse is more than knowing just the alphabet. To make communication efficient, there are many internationally agreed patterns of communication.

A sample CW conversation between station 1 (S1) and station 2 (S2)

S1:

CQ CQ CQ DE S1 K
Calling anyone (CQ), this is (DE) S1, listening (K)

S2:

S1 DE S2 KN
Calling S1, this is S2, back-to-you (KN)
(Now we have a connection)

S1:

S2 DE S1 = GA DR OM UR RST 599 HR = QTH TIMBUKTU = OP IS MIKE = HW? + S2 DE S1 KN
Good afternoon dear old man. You are RST 599 here.  
(Very readable (5), very strong signal (9), very good tone (9))
I'm located in Timbuktu. The operator's name is Mike.
How do you copy?

S2:

S1 DE S2 = TNX FB RPRT DR OM MIKE UR 558 = QTH HIMALAYA = NAME IS YETI + S1 DE S2 KN
Thanks for the nice report dear old man Mike. I read you 558.
I am in the Himalayas. My name is Yeti.

S1:

S2 DE S1 = OK TNX QSO DR YETI = 73 ES HPE CUAGN + S2 DE S1 KN
Okay, thanks for this conversation, dear Yeti.
Best regards and hope to see you again.

S2:

S1 DE S2 = R TU CUAGN 73 + S1 DE S2 SK
Understood. Thank you. Best regards. (signing off)

With heavy use of the Q code and abbreviations, surprisingly meaningful conversations can be had. Note that not a single English word has been used, only abbreviations. S1 and S2 might not speak the same native language.

Of course, real rag-chewing (lengthy conversations) cannot be done without a common language. On the worldwide amateur bands this is often English.

Contesters often use a very specialized and even shorter format for their contacts. Their purpose is to process as many contacts as possible in a limited time (e.g. 100-150 per hour).

See also

External links

  • Morse Telegraph Club, Inc. (http://www.morsetelegraphclub.org/) (The Morse Telegraph Club is an international non-profit organization dedicated to the perpetuation of the knowledge and traditions of telegraphy.)

Morse code translators and software

Learn Morse code:

There are a number of translators on the Web that will convert text to Morse code, and play it via a PC:

And for Series 60 phones:

Online Chat in morse code [4] (http://www.mrx.com.au) Click on link for CW Communicator. No license needed, can use keyboard, or key connected to serial port or joystick to generate sound.

Notes

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