Morse
code is a method of transmitting
text information as a series of on-off tones, lights, or clicks that
can be directly understood by a skilled listener or observer without
special equipment. The International Morse Code[1]
encodes the
ISO basic Latin alphabet, some extra Latin letters, the
Arabic numerals and a small set of punctuation and procedural
signals as standardized sequences of short and long signals called
"dots" and "dashes",[1]
or "dits" and "dahs". Because many non-English natural languages use
more than the 26 Roman letters, extensions to the Morse alphabet exist
for those languages.
Each character (letter or numeral) is represented by a unique
sequence of dots and dashes. The duration of a dash is three times the
duration of a dot. Each dot or dash is followed by a short silence,
equal to the dot duration. The letters of a word are separated by a
space equal to three dots (one dash), and two words are separated by a
space equal to seven dots. The dot duration is the basic unit of time
measurement in code transmission.[1]
For efficiency, the length of each character in Morse is approximately
inversely proportional to its frequency of occurrence in English. Thus,
the most common letter in English, the letter "E," has the shortest
code, a single dot.
Morse code is most popular among
amateur radio operators, although it is no longer required for
licensing in most countries, including the US.
Pilots and
air traffic controllers usually need only a cursory understanding.
Aeronautical
navigational aids, such as
VORs and
NDBs, constantly identify in Morse code. Compared to voice, Morse
code is less sensitive to poor signal conditions, yet still
comprehensible to humans without a decoding device. Morse is therefore a
useful alternative to synthesized speech for sending automated data to
skilled listeners on voice channels. Many
amateur radio repeaters, for example, identify with Morse, even
though they are used for voice communications.
"SOS", the standard emergency signal, in Morse code.
For emergency signals, Morse code can be sent by way of improvised
sources that can be easily "keyed" on and off, making it one of the
simplest and most versatile methods of
telecommunication. The most common distress signal is
SOS or three
dots, three dashes and three dots, internationally recognized by treaty.
Development
and history
A typical "straight key." This U.S. model, known as the
J-38, was manufactured in huge quantities during
World War II, and remains in widespread use today. In a
straight key, the signal is "on" when the knob is pressed,
and "off" when it is released. Length and timing of the dots
and dashes are entirely controlled by the operator.
Beginning in 1836, the American artist
Samuel F. B. Morse, the American
physicist
Joseph Henry, and
Alfred Vail developed an
electrical telegraph system. This system sent pulses of
electric current along wires which controlled an
electromagnet that was located at the receiving end of the telegraph
system. A code was needed to transmit natural language using only these
pulses, and the silence between them. Morse therefore developed the
forerunner to modern International Morse code.
In 1837,
William Cooke and
Charles Wheatstone in
England
began using an electrical telegraph that also used electromagnets in its
receivers. However, in contrast with any system of making sounds of
clicks, their system used pointing needles that rotated above
alphabetical charts to indicate the letters that were being sent. In
1841, Cooke and Wheatstone built a telegraph that printed the letters
from a wheel of typefaces struck by a hammer. This machine was based on
their 1840 telegraph and worked well; however, they failed to find
customers for this system and only two examples were ever built.[2]
On the other hand, the three Americans' 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 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.
The Morse code was developed so that operators could translate the
indentations marked on the paper tape into text messages. In his
earliest code, Morse had planned to only transmit numerals, and use a
dictionary to look up each word according to the number which had been
sent. However, the code was soon expanded by
Alfred Vail to include letters and special characters, so it could
be used more generally. Vail determined 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.[3]
The shorter marks were called "dots", and the longer ones "dashes", and
the letters most commonly used were assigned the shorter sequences of
dots and dashes.
Comparison of historical versions of Morse code with the
current standard. 1. American Morse code as originally
defined. 2. The modified and rationalised version used by
Gerke on German railways. 3. The current
ITU standard.
In the original Morse telegraphs, the receiver's armature made a
clicking noise as it moved in and out of position to mark the paper
tape. The telegraph operators soon learned that they could translate the
clicks directly into dots and dashes, and write these down by hand, thus
making it unnecessary to use a paper tape. When Morse code was adapted
to
radio communication, the dots and dashes were sent as short and long
pulses. It was later found that people became more proficient at
receiving Morse code when it is taught as a language that is heard,
instead of one read from a page.[4]
To reflect the sounds of Morse code receivers, the operators began to
vocalise a dot as "dit", and a dash as "dah". Dots which are not the
final element of a character became vocalised as "di". For example, the
letter "c" was then vocalised as "dah-di-dah-dit".[5][6]
In the 1890s, Morse code began to be used extensively for early
radio
communication, before it was possible to transmit voice. In the late
nineteenth and early twentieth century, most high-speed international
communication used Morse code on telegraph lines, undersea cables and
radio circuits. In aviation, Morse code in radio systems started to be
used on a regular basis in the 1920s. Although previous transmitters
were bulky and the
spark gap system of transmission was difficult to use, there had
been some earlier attempts. In 1910 the U.S. Navy experimented with
sending Morse from an airplane.[7]
That same year a radio on the airship
America had been instrumental in coordinating the rescue of
its crew.[8]
However, there was no aeronautical radio in 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 the
Spirit of St. Louis were off the ground, Lindbergh was truly
alone and incommunicado. On the other hand, when the first
airplane flight was made from California to Australia in the 1930s
on the
Southern Cross, one of its four crewmen was its 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 identification of navigational beacons which
transmitted continuous two- or three-letter identifiers in Morse code.
Aeronautical charts show the identifier of each navigational aid
next to its location on the map.
Radio telegraphy using Morse code was vital during
World War II, especially in carrying messages between the
warships
and the
naval bases of the
Royal Navy, the
Kriegsmarine, the
Imperial Japanese Navy, the
Royal Canadian Navy, the
Royal Australian Navy, the
U.S. Navy, and the
U.S. Coast Guard. Long-range ship-to-ship communications 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 these navies to scout for enemy
warships, cargo ships, and troop ships.
In addition, rapidly moving armies in the field could not have fought
effectively without radiotelegraphy, because they moved more rapidly
than telegraph and telephone lines could be erected. This was seen
especially in the
blitzkrieg offensives of the
Nazi German
Wehrmacht in
Poland,
Belgium,
France
(in 1940), 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.
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 on January 31, 1997, the final
message transmitted was "Calling all. This is our last cry before our
eternal silence."[9]
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 CW medium frequency (MF) distress frequency of
500 kHz.[citation
needed]
User proficiency
A commercially manufactured iambic paddle used in
conjunction with an electronic keyer to generate high-speed
Morse code, the timing of which is controlled by the
electronic keyer. Manipulation of dual-lever paddles is
similar to the
Vibroplex, but pressing the right paddle generates a
series of
dahs, and squeezing the paddles produces
dit-dah-dit-dah sequence. The actions are reversed for
left-handed operators.
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 dots
and dashes. Consequently words also have different lengths in terms of
dot duration, even when they contain the same number of characters. For
this reason, a standard word is helpful to measure operator transmission
speed. "PARIS" and "CODEX" are two such standard words.[10]
Operators skilled in Morse code can often understand ("copy") code in
their heads at rates in excess of 40 wpm.
International contests in code copying are still occasionally held.
In July 1939 at a contest in
Asheville, North Carolina in the
United States Ted R. McElroy set a still-standing record for Morse
copying, 75.2 wpm.[11]
In his online book on high speed sending, William Pierpont N0HFF notes
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
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 dot durations versus 60
dot durations) and different interword gaps (5 dot durations versus 7
dot durations) may have been used when determining such speed records.
For example speeds run with 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.[12]
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
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.
International Morse Code
Morse code has been in use for more than 160 years—longer than any
other
electrical coding system. What 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 resulting substantially in the modern form of the code.
After some minor changes, International Morse Code was standardized at
the International Telegraphy Congress in 1865 in Paris, and was later
made the standard by the
International Telecommunication Union (ITU). Morse's original code
specification, largely limited to use in the United States and Canada,
became known as
American Morse code or railroad code. American Morse code is
now seldom used except in historical re-enactments.
Aviation
In
aviation, instrument pilots use
radio navigation aids. To ensure that the stations the pilots are
using are serviceable, the stations all transmit a short 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 based at
Manchester Airport in England is abbreviated as "MCT", and MCT in
Morse code is
transmitted on its radio frequency. In some countries, if a VOR
station begins malfunctioning it broadcasts "TST" (for "TEST"), which
tells
pilots and
navigators that the station is unreliable. In Canada, the
identification is removed entirely to signify the navigation aid is not
to be used.[13]
Amateur radio
Vibroplex semiautomatic key (also called a "bug"). The
paddle, when pressed to the right by the thumb, generates a
series of
dits, the length and timing of which are
controlled by a sliding weight toward the rear of the unit.
When pressed to the left by the knuckle of the index finger,
the paddle generates a
dah, the length of which is
controlled by the operator. Multiple
dahs require
multiple presses. Left-handed operators use a key built as a
mirror image of this one.
International Morse code today is most popular among
amateur radio operators, where it is used as the pattern to key a
transmitter on and off in the radio communications mode commonly
referred to as "continuous
wave" or "CW" to distinguish it from spark transmissions, not
because the transmission was continuous. Other keying methods are
available in radio telegraphy, such as
frequency shift keying.
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 the amateur radio licensing procedure worldwide.
However, the World Radiocommunication Conference of 2003 made the Morse
code requirement for amateur radio licensing optional.[14]
Many countries subsequently removed the Morse requirement from their
licence requirements.[15]
Until 1991 a demonstration of the ability to send and receive Morse
code at five words per minute (wpm) was required to receive an amateur
radio license for use in the United States from the
Federal Communications Commission. Demonstration of this ability was
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 (Amateur Extra Class);
effective April 15, 2000, the FCC reduced the Extra Class requirement to
five wpm.[16]
Finally, effective on February 23, 2007 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, HF, UHF, and VHF. In some countries, certain portions of the
amateur radio bands are reserved for transmission of Morse code signals
only.
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). OM (old man), YL (young
lady) and XYL ("ex-YL" — wife) are common abbreviations. YL or OM is
used by an operator when referring to the other operator, XYL or OM is
used by an operator when referring to his or her spouse. This use of
abbreviations for common terms permits conversation even when the
operators speak different languages.
Although the traditional
telegraph key (straight key) is still used by some amateurs, the use
of mechanical semi-automatic
keyers
(known as "bugs") and of fully automatic electronic
keyers is
prevalent today.
Software is also frequently employed to produce and decode Morse
code radio signals.
Other uses
A U.S. Navy seaman sends Morse code signals in 2005.
As of 2010 commercial radiotelegraph licenses using code tests based
upon the CODEX standard word are still being issued in the United States
by the Federal Communications Commission. Designed for shipboard and
coast station operators, licenses are awarded to applicants who pass
written examinations on advanced radio theory and show 20 wpm code
proficiency [this requirement is currently waived for "old" (20 wpm)
Amateur Extra Class licensees]. However, since 1999 the use of satellite
and very high frequency maritime communications systems (GMDSS)
have made them obsolete.
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.[17]
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 a way to communicate while maintaining
radio silence.
Applications for the general public
Representation of SOS-Morse code.
An important application is signalling for help through
SOS, "· · · – – – · · ·".
This can be sent many ways: keying a radio on and off, flashing a
mirror, toggling a flashlight and similar methods. SOS is not three
separate characters, rather, it is a prosign
SOS, and is keyed without
gaps between characters.[18]
Morse code as an assistive technology
Morse code has been employed as an
assistive technology, helping people with a variety of
disabilities to communicate. Morse can be sent by persons with
severe motion disabilities, as long as they have some minimal motor
control. An original solution to the problem that care takers have to
learn to decode has been an electronic typewriter with the codes written
on the keys. Codes were sung by users; see the voice typewriter
employing morse or votem, Newell and Nabarro, 1968.
Morse code can also be translated by computer and used in a speaking
communication aid. In some cases this means alternately blowing into and
sucking on a plastic tube ("sip-and-puff"
interface). An important advantage of Morse code over
row column scanning is that, once learned, it does not require to
look at a display. Also, it appears faster than scanning.
People with severe motion disabilities in addition to sensory
disabilities (e.g. people who are also deaf or blind) can receive Morse
through a skin buzzer.[citation
needed].
In one case reported in the radio amateur magazine
QST, an
old shipboard radio operator who had a
stroke
and lost the ability to speak or write could communicate with his
physician (a radio amateur) by blinking his eyes in Morse. Another
example occurred in 1966 when
prisoner of war
Jeremiah Denton, brought on television by his North Vietnamese
captors, Morse-blinked the word TORTURE. In these two cases
interpreters were available to understand those series of eye-blinks.
Representation, timing and speeds
International Morse code is composed of five elements:
- short mark, dot or "dit" (·) — "dot duration" is one unit long
- longer mark, dash or "dah" (–) — three units long
- inter-element gap between the dots and dashes within a character
— one dot duration or one unit long
- short gap (between letters) — three units long
- medium gap (between words) — seven units long[1]
Morse code can be transmitted in a number of ways: originally as
electrical pulses along a
telegraph wire, but also as an audio tone, a radio signal with short
and long tones, or as a mechanical or visual signal (e.g. a flashing
light) using devices like an
Aldis lamp or a
heliograph.
Morse code is transmitted using just two states (on and off) so it
was an early form of a
digital
code. Strictly speaking it is not
binary, as there are five fundamental elements (see
quinary).
However, this does not mean Morse code cannot be represented as a binary
code. In an abstract sense, this is the function that telegraph
operators perform when transmitting messages. Working from the above
definitions and further defining a 'unit' as a
bit, we can
visualize any Morse code sequence as a combination of the following five
elements:
- short mark, dot or "dit" (·) — 1
- longer mark, dash or "dah" (–) — 111
- intra-character gap (between the dots and dashes within a
character) — 0
- short gap (between letters) — 000
- medium gap (between words) — 0000000
Note that this method assumes that dits and dahs are always separated
by dot duration gaps, and that gaps are always separated by dits and
dahs.
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 addition, individual operators differ
slightly, for example using slightly longer or shorter dashes or gaps,
perhaps only for particular characters. This is called their "fist", and
operators can recognize specific individuals by it alone. A good
operator who sends clearly and is easy to copy is said to have a "good
fist". A "poor fist" is a characteristic of sloppy or hard to copy Morse
code.
An operator must choose two speeds when sending a message in Morse
code. First, the operator must choose the character speed, or how fast
each individual letter is sent. Second, the operator must choose the
text speed, or how fast the entire message is sent. Both speeds can be
the same, but often they are not the same. An operator could generate
the characters at a high rate, but by increasing the space between the
letters, send the message more slowly.
Using different character and text speeds is, in fact, a common
practice, and is used in the Farnsworth method of
learning Morse code. Because Morse code is usually hand generated,
an operator may retain a certain comfortable character speed, but vary
the text speed by varying the spacing between the letters.
All Morse code elements depend on the dot length. A dash is the
length of 3 dots, and spacings are specified in number of dot lengths.
Because of this, some method to standardize the dot length is useful. A
simple way to do this is to send the same five-character word over and
over for one minute at a speed that will allow the operator to send the
correct number of words in one minute. If, for example, the operator
wanted a character speed of 13 words per minute, the operator would send
the five-character word 13 times in exactly one minute. From this, the
operator would arrive at a dot length necessary to produce 13 words per
minute while meeting all the standards.
The word one chooses determines the dot length. A word with more
dots, like PARIS, would be sent with longer dots to fill in one minute.
A word with more dashes, like CODEX, would produce a shorter dot length
so everything would fit into 1 minute. PARIS or CODEX are frequently
used as a Morse code standard word. Using the word PARIS as a standard,
the number of dot units is 50 and a simple calculation shows that the
dot length at 20 words per minute is 60 milliseconds. Using the word
CODEX with 60 dot units, the dot length at 20 words per minute is 50
milliseconds.
Because Morse code is usually sent by hand, it is unlikely that an
operator could be that precise with the dot length, and the individual
characteristics and preferences of the operators usually override the
standards.
For commercial radiotelegraph licenses in the United States, the
Federal Communications Commission specifies tests for Morse code
proficiency in words per minute of text speed.[19]
The commission does not specify character speeds. For proficiency at 20
words per minute, it would be impossible to generate characters at less
than that speed. If, for example, the characters were generated at a
rate to produce 5 words in one minute, the examiner could not send 20
words in one minute. Conversely, the examiner could generate characters
at a rate to produce 24 words per minute, but increase the character
spacing to send the message at 20 words per minute. The regulation,
however, only specifies the number of words to be received in one
minute.
While the Federal Communications Commission no longer requires Morse
code for amateur radio licenses, the old requirements were similar to
the requirements for commercial radiotelegraph licenses.[20]
There was no requirement for any particular character speed, but the
examinee had to send and receive a message at a specified text speed.
A difference between amateur radio licenses and commercial
radiotelegraph licenses is that commercial operators must be able to
receive code groups of random characters along with plain language text.
For each class of license, the code group speed requirement is slower
than the plain language text requirement. For example, for the Second
Class Radiotelegraph License, the examinee must pass a 20 word per
minute plain text test and a 16 word per minute code group test.[21]
Receiving a plain language text is easier than receiving code groups; an
operator may anticipate the next letter, or, indeed, the next word in a
plain text message. This is impossible with random code groups.
Based upon a 50 dot duration standard word such as PARIS, the time
for one dot duration or one unit can be computed by the formula:
- T = 1200 / W
or
- T = 6000 / C
Where: T is the unit time, or dot duration, in milliseconds,
W is the speed in
wpm, and C is the speed in
cpm.
Below is an illustration of timing conventions. The phrase "MORSE
CODE", in Morse code format, would normally be written something like
this, where – represents dahs and · represents dits:
–– ––– ·–· ··· · –·–· ––– –·· ·
M O R S E C O D E
Next is the exact conventional timing for this phrase, with =
representing "signal on", and . representing "signal off", each
for the time length of exactly one dit:
1 2 3 4 5 6 7 8
12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789
M------ O---------- R------ S---- E C---------- O---------- D------ E
===.===...===.===.===...=.===.=...=.=.=...=.......===.=.===.=...===.===.===...===.=.=...=
^ ^ ^ ^ ^
| dah dit | |
symbol space letter space word space
Morse code is often spoken or written with "dah" for dashes, "dit"
for dots located at the end of a character, and "di" for dots located at
the beginning or internally within the character. Thus, the following
Morse code sequence:
M O R S E C O D E
–– ––– ·–· ··· · (space) –·–· ––– –·· ·
is orally:
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, for both sending and receiving.
Link budget issues
Morse Code cannot be treated as a classical
radioteletype (RTTY) signal when it comes to calculating a
link margin or a
link budget[citation
needed] for the simple reason of it possessing
variable length dots and dashes as well as variant timing between
letters and words. However, because Morse Code when transmitted
essentially creates an AM signal (even in on/off keying mode),
assumptions about signal can be made with respect to similarly timed
RTTY signalling.
Because Morse code transmissions employ an
on-off keyed radio signal, it requires less complex transmission
equipment than other forms of radio communication. Morse code also
requires less
signal bandwidth than voice communication, typically 100–150
Hz[citation
needed], compared to the roughly 2400 Hz used by
single-sideband voice, although at a lower data rate.
Morse code is usually received as a medium-pitched audio tone
(600-1000 Hz), 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 transmitted power is concentrated
into a limited bandwidth so narrow receiver filters can be used to
suppress interference from adjacent frequencies. The narrow signal
bandwidth also takes advantage of the natural aural selectivity of the
human brain, further enhancing weak signal readability. This efficiency
makes CW extremely useful for
DX (distance)
transmissions, as well as for low-power transmissions (commonly
called "QRP
operation", from the
Q-code for "reduce power").
Learning methods
People learning Morse code using the Farnsworth method are
taught to send and receive 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. The Farnsworth method is
named for Donald R. "Russ" Farnsworth, also known by his
call
sign, W6TTB. However, initially exaggerated spaces between symbols
and words are used, to give "thinking time" to make the sound "shape" of
the letters and symbols easier to learn. The spacing can then be reduced
with practice and familiarity. Another popular teaching method is the
Koch method, named after German psychologist Ludwig Koch, which uses
the full target speed from the outset, but begins with just two
characters. Once strings containing those two characters can be copied
with 90% accuracy, an additional character is added, and so on until the
full character set is mastered.
In North America, many thousands of individuals have increased their
code recognition speed (after initial memorization of the characters) by
listening to the regularly scheduled code practice transmissions
broadcast by
W1AW, the American Radio Relay League's headquarters station.
In the United Kingdom many people learned the Morse code by means of
a series of words or phrases that have the same rhythm as a Morse
character. For instance, "Q" in Morse is dah-dah-di-dah, which can be
memorized by the phrase "God save the Queen", and the Morse for "F" is
di-di-dah-dit, which can be memorized as "Did she like it."
A well-known Morse code rhythm from the Second World War period
derives from Beethoven's Fifth Symphony, the opening phrase of which was
regularly played at the beginning of BBC broadcasts. The timing of the
notes corresponds to the Morse for "V"; di-di-di-dah and stood for "V
for Victory" (as well as the Roman numeral for the number five).[22][23]
Letters, numbers, punctuation
There is no standard representation for the exclamation mark (!),
although the KW
digraph (– · – · – –) was proposed in the 1980s by the
Heathkit Company (a vendor of assembly kits for amateur radio
equipment). While Morse code translation software prefers this version,
on-air use is not yet universal as some amateur radio operators in
Canada and the USA continue to prefer the older
MN digraph (– – – ·)
carried over from American landline telegraphy code.
The &, $ and _ signs are not defined inside the ITU recommendation on
Morse code. The $ sign code was represented in the
Phillips Code, a huge collection of abbreviations used on land line
telegraphy, as SX. The
representation of the & sign given above, often shown as
AS, is also the Morse
prosign for wait. In addition, the American landline
representation of an ampersand was similar to "ES" (· · · ·) and
hams have carried over this usage as a synonym for "and" (WX HR COLD ES
RAINY, "the weather here is cold & rainy").
On May 24, 2004 — the 160th anniversary of the first public Morse
telegraph transmission — the Radiocommunication Bureau of the
International Telecommunication Union (ITU-R)
formally added the @ ("commercial
at" or "commat") character to the official Morse character set,
using the sequence denoted by the
AC digraph (· – – · – ·).
This sequence was reportedly chosen to represent "A[T] C[OMMERCIAL]" or
a letter "a" inside a swirl represented by a "C".[24]
The new character facilitates sending
email
addresses by Morse code and is notable since it is the first official
addition to the Morse set of characters since
World War I.
Prosigns
Meaning |
Code |
Meaning |
Code |
Meaning |
Code |
Wait |
· – · · · |
Error |
· · · · · · · · |
Understood |
· · · – · |
Invitation to transmit |
– · – |
End of work |
· · · – · – |
Starting Signal |
– · – · – |
Defined in the ITU recommendation.
Non-English
extensions
Character(s) |
Code |
Character(s) |
Code |
Character(s) |
Code |
ä
(also æ
and ą) |
· – · – |
è
(also
ł) |
· – · · – |
ñ
(also ń) |
– – · – – |
à
(also å) |
· – – · – |
é
(also
đ and ę) |
· · – · · |
ö
(also ø
and ó) |
– – – · |
ç
(also ĉ
and ć) |
– · – · · |
ĝ |
– – · – · |
ŝ |
· · · – · |
ch (also
š) |
– – – – |
ĥ |
– · – – · (Obsolete)
– – – – (New) |
þ ("Thorn") |
· – – · · |
ð ("Eth") |
· · – – · |
ĵ |
· – – – · |
ü
(also ŭ) |
· · – – |
ś |
· · · – · · · |
ź |
– – · · – · |
ż |
– – · · – |
Non-Latin
extensions
For
Chinese,
Chinese telegraph code is used to map
Chinese characters to four-digit codes and send these digits out
using standard Morse code.
Korean Morse code uses the
SKATS
mapping, originally developed to allow Korean to be typed on western
typewriters. SKATS maps
hangul
characters to arbitrary letters of the
Latin script and has no relationship to pronunciation in
Korean.
Alternative display of more common characters in International Morse
code
Some methods of teaching or learning Morse code use the
dichotomic search table below.
A graphical representation of the dichotomic search
table: the user branches left at every dot and right at
every dash until the character is finished.
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 · · · · |
In modern culture
Ronnie Hazlehurst, a man famous for his theme tune compositions for
BBC series, followed the sound of Morse code for the title of each of
the letters of the 1970s British sitcom
Some Mothers Do 'Ave 'Em in its very own theme tune.[25]
See also
References
- ^
a
b
c
d
e
"International Morse code Recommendation ITU-R M.1677-1".
itu.int. International Telecommunication Union. October 2009.
Retrieved 23 December 2011.
-
^
Burns 2004, p. 79
-
^
Burns 2004, p. 84
-
^
ARRLWeb: ARRLWeb: Learning Morse Code (CW)!
-
^
L. Peter Carron, "Morse Code: The
Essential Language", Radio amateur's library, issue 69,
American Radio Relay League, 1986
ISBN 0-87259-035-6.
-
^
R. J. Eckersley, Amateur radio
operating manual,
Radio Society of Great Britain, 1985
ISBN 0-900612-69-X.
-
^
History of Communications-Electronics in the United States Navy
-
^
100 Years ago this airship sailed from Atlantic City
-
^
"An obituary for Morse code", The Economist, January
23, 1999.
-
^
Perera, Tom.
"The "Morse" Code and the Continental Code". W1TP
Telegraph & Scientific Instruments Museums.
Retrieved 23 December 2011.
-
^
"The Art & Skill of Radio Telegraphy". April 20, 2002.
Retrieved 2006-04-21.
-
^
Extremely High Speed Club official web page
-
^
COM 3.2, Canadian AIM
-
^
IARUWeb: The International Amateur Radio Union
-
^
"Italy Joins No-Code Ranks as FCC Revives Morse Debate in the
US". The ARRL Letter 24 (31). August 12, 2005.
Retrieved 2012-04-02.
-
^
"1998 Biennial Regulatory Review — Amendment of Part 97 of the
Commission's Amateur Service Rules" (PDF). Archived from
the original on October 31, 2005.
Retrieved December 4, 2005.
-
^
"Aeronautical Information Manual (AIM)".
Retrieved 2007-12-10.
-
^
http://www.qsl.net/w8rit/prosigns.htm rel="nofollow">
-
^
Title 47 Code of Federal
Regulations §13.207(c) and Title 47 Code of Federal Regulations
§13.209(d)
-
^
Title 47 Code of Federal
Regulations §97.503, 1996 version
-
^
Title 47 Code of Federal
Regulations §13.203(b)
-
^
Glenn Stanley, The Cambridge
Companion to Beethoven, p.269, Cambridge University Press,
2000
ISBN 0-521-58934-7.
-
^
William Emmett Studwell, The
Americana Song Reader, p.62, Routledge, 1997
ISBN 0-7890-0150-0.
-
^
"International Morse Code Gets a New ITU Home, New Character".
Archived from
the original on September 30, 2007.
Retrieved February 27, 2007.
-
^
Does the Frank Spencer music have Morse code? BBC News, 4
October 2007
- Burns, R. W.
(2004), Communications: an international history of the formative
years, Institution of Electrical Engineers,
ISBN 0-86341-327-7
External links