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Morse code
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Morse code

Morse code is a system of representing letters, numbers and punctuation marks by means of a code signal sent intermittently. It was developed by Samuel Morse and Alfred Vail in 1835.

Morse code is an early form of digital communication, however unlike modern binary digital codes that use just two states (commonly represented as 1 and 0), it uses five: dot (), dash (-), short gap (between each letter), medium gap (between words) and long gap (between sentences).

Table of contents
1 History of Morse code
2 American Morse Code
3 Modern International Morse Code
4 Timing and representation
5 Letters, numbers, punctuation, prosigns
6 Commonly-used Morse code abbreviations
7 Conversation with Morse code
8 Morse Code translators and software

History of Morse code

Morse became interested in telegraphy in 1832, and worked out the basics of a relay system in 1835. The equipment was gradually improved and was demonstrated in 1837. Morse developed "lightning wires" and "Morse code", and applied for a patent in 1840. A line was constructed between Baltimore and Washington and the first message, sent on May 24, 1844, was "What hath God wrought!"

Morse's original code consisted of combinations of dots and dashes that represented numbers. Each number represented a word. This required looking up the number in a book to find the word it represented. A telegraph key was then used to tap out the sequence of dots and dashes, and pauses that represented the number.

Although Morse invented the telegraph, he lacked technical expertise. He entered an agreement with Alfred Vail who built more practical equipment. Vail developed a system in which each letter or symbol is sent individually, using combinations of dots, dashes, and pauses. Morse and Vail agreed that Vail's method of representing individual symbols would be included in Morse's patent. This system, known American Morse code, was the version that was used to transmit the first telegraph message.

The code may transmitted as an audio tone, a steady radio signal switched on and off (only the carrier wave, or CW, also continuous wave), an electrical pulse down a telegraph wire, or as a mechanical or visual signal (e.g. a flashing light).

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. American Morse Code was used in the wired telegraph systems that made up the first long-distance electronic communication system. International Morse Code, which uses only dots and dashes (eliminating the pause), is used today.

Telegraph companies charged based on the length of the message sent. Elaborate commercial codes were developed that encoded complete 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 we would say the commercial code is layered on top of Morse code. 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.

On January 8, 1838 Alfred Vail demonstrated a telegraph code using dots and dashes which was the forerunner of Morse code.

When considered as a standard for information encoding, Morse code had a successful lifespan that has not yet been surpassed by any other encoding scheme. Morse code was used as an international standard for maritime communication until 1999. 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."

American Morse Code

Virtually extinct, and no longer in commercial use, American Morse Code, sometimes referred to as "Railroad Morse" uses a slightly different structure of dots and dashes and uniquely spaces also to represent numbers, letters, and special characters. This style of Morse code was developed for land operators working over telegraph wire rather than via radio signals. It is most frequently seen today in railroad museums and American civil war re-enactments.

This older style of code was developed to accommodate the way in which operators listened to Morse code sent to them. Rather than hearing tones from a speaker or headphones as we do now using International Morse Code, in these earliest days of telegraphy one would hear two clicks from a mechanical sounding device for each key movement. Pressing the key makes a click, and releasing the key makes a clack. Thus, each key movement, up or down was uniquely heard. In this mechanical sounder system, an "A" (-) would sound like: clickClack click - - - Clack. This is quite different from "CW" code where beeps are heard for as long as the key is engaged.

Most often land line telegraph operators worked for a railroad or later for Western Union and news reporting services. Thomas Alva Edison was such an operator in his teenage years, as were countless youths of his time.

Modern 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 a steady (unmodulated) 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 very little bandwidth, typically 100-150 Hz, and facilitates communication between amateur radio operators who do not share a common mother tongue and would have great difficulty in communicating using voice modes.

It is also very popular among QRP operators for enabling very long distance communication. A Morse code signal is very difficult to swamp out with interference. 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 very narrow receiver practical. A narrow receiver uses filters to exclude interference thus singling out the Morse code signal. Concentrating the transmitted energy in such a small bandwidth gives the signal a "spectral brightness" that is much higher than the average noise, both man-made and natural.

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 permitting use of the HF bands. Until 1999 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.[1]

The World Radiocommunication Conference of 2003 (WRC-03) made optional the international Morse code requirement for amateur radio licensing. Although the requirement remains on the books in the US, Canada, and elsewhere, some countries are working to eliminate the requirement entirely.

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 is still used by many amateurs, the use of semi- and fully-automatic electronic keyers is prevalent today. Computer software is also frequently employed to produce and decode Morse code RF signals.

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 the letter a inside the swirl appearing to be a C)[1]. It is notable since this is the first addition to the Morse set of characters since World War I.

Timing and representation

There are two "symbols" used to represent letters, called dots and dashes or 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 dit | word space symbol space letter space

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.

(Beginners are taught to send short fast letters with small spaces between the dots and dashes in a symbol and exaggerated spaces between symbols and words. This makes it easier to learn.)

People familiar with Morse Code often speak or write it like this. ("Dah" is pronounced with an "awe" vowel sound).

-- --- -   / -- --- - 

DahDah DahDahDah DiDahDit DiDiDit Dit, DahDiDahDit DahDahDah DahDiDit Dit.

Letters, numbers, punctuation, prosigns

Letter International
Letter International
A - - N - -
B - - O - - - - - -
C - - _ P - -
D - - Q - - - -
E R - _
F - - S
G - - - - T - -
H U - -
I V - -
J - - - - - W - - - -
K - - - - X - - -
L - - - - - Y - - - _
M - - - - Z - - _
(† Note: "_" signifies "Space" which is part of the character)


International  American 
   code        Morse
0  -----      -----
1  ----      --
2  ---      - 
3  --      - 
4  -      -
5        --- 
6  -      
7  --      --
8  ---      -
9  ----      --

Common punctuation

             International  American
                Code         Morse
Period         ---       -- 
Comma          ----       --
Question mark  --       --
Apostrophe     ----
Brackets       ----
Colon          ---
Double dash    --
Equals sign    --
Fraction bar   --\
Hyphen         --
Quotation mark --
"@" (commat)   ---  (added in 2004, combines A and C into one character)

Special symbols (prosigns)

Prosigns are dot/dash sequences that have a special meaning. They are composed of two Morse code alphabetic characters "run together"; that is, that omit the normal pause that would occur if they were being sent as two letters of text. They are normally represented in print by the two letters, often with a ligating bar above them.

AR  --  Stop (end of message), often written +
AS  -  Wait (for 10 seconds), respond with C (yes)
           AS2 means wait 2 min, AS5 5 mins, etc
           For pauses of 10 min or longer, you must use QRX (see Q code)
K   --    Invitation to transmit  (normally follows AR to indicate "back-to-you")
KN  ----  As above but indicating "back-to-you-and-no-one-else" (sometimes used)
SK  -- End (end of contact), more accurately illustrated as VA overscored, in Europe written as "@".
BT  --  Separator, better illustrated as TV overscored, is sometimes written =
SN  -  Understood, written as a long "f" stretching below and above other characters.

Not really prosigns, an error may be indicated by any of:
       Error, correct word follows (defined to be any letter with at six 
              or more dots in a row)
           Error (unofficial, easily identifiable since sent with a "broken" rhythm)
          Not really an error, but indicate repetition of last word
              for clarity, eg. HELLO .. .. HELLO (seldom used)

Non-English extensions to the Morse code

  --- (also )
ĉ  -- 
ch '''----'''
ĝ  ---  
ĥ  ---
ĵ  --- 
ŝ  - 
  -- (also ŭ) 
"  --
!  --

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
CS    Callsign
CUL   See you later
CUZ   Because
CW    Continuous wave
CX    Conditions
DE    From
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
SIGS  Signals
SKED  Schedule
SN    Soon
SOS   International Distress Call
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 of any female)
73    Best regards
88    Love and kisses

See also: Q code

Conversation with 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)


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

S1 DE S2 K
Calling S1, this is S2, listening
(Now we have a connection)

Good afternoon dear old man. You are RST 599 here. 
I'm located in Timbuktu. The operator's name is Mike. 
How do you copy? 

Thanks for the nice report dear old man Mike. I read you 558. 
I am in the Himalayas. My name is Yeti.

Okay, thanks dear Yeti for this conversation. 
Best of luck to you and hope to see you again.

S1 DE S2 = R TU CUAGN 73 = + S1 DE S2 + SK
Understood. Thank you. Best of luck. (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. Perhaps Yeti does not understand a word of English?

Of course, real rag-chewing cannot be done without a common language. On the bands this is often English.

Contesters often use a very specialized and short format for the contact. The purpose is to process as many contacts per time unit (100-150 per hour).

Morse Code translators and software

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