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Morse code is a system of representing letters, numbers and punctuation marks by means of a code signal sent intermittently. It was developed by Alfred Vail while he was helping Samuel Morse with Morse's invention of the telegraph (1835) which is considered a fore-runner of digital modes of communication (see e-mail).

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

Although Morse invented the telegraph, he lacked technical expertise. He entered an agreement with Alfred Vail who built more practical equipment. Vail developed a code where each letter or symbol is sent individually. Per their agreement Vail's method representing individual symbols was included on Morse's patent. It is this kind of code that was used for the first telegraph message.

The code is transmitted either as an audio tone, a steady radio signal switched on and off (known as continuous wave, or CW), an electrical pulse down a telegraph wire, or as a mechanical or visual signal (eg. a flashing light).

Any code representing written symbols as variable length signals can be called a Morse code in general but specifically the term is used 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" is most commonly 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 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 succesful lifespan that has not yet been surpassed by any other encoding scheme. Morse code was used as an international standard for ship-to-ship 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."

International Morse Code

International Morse Code is still in use today, although it has become almost exclusively the province of amateur radio operators. In some countries, certain parts of the amateur radio bands are still reserved for transmission of morse code signals only. Since Morse relies only on 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 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.

In the United States until the 1991, a demonstration of the ability to send and receive morse code sent 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); on December 13, 1999, the FCC reduced the Extra Class requirement 13 WPM. 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.

Timing and representation:

There are two "symbols" used, 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.

Here's a table including the alphabet and some other commonly used symbols:

The numbers are as follows:

0 -----
1 *----
2 **---
3 ***--
4 ****-
5 *****
6 -****
7 --***
8 ---**
9 ----*

Common punctuation:

. *-*-*-
, --**--
? **--**
- -***-
/ -**-*

Special characters:

Error ***-* (I will send the last word again)
(Also error ********)
+, AR *-*-* Stop (end of message)
@ ***-*- End (end of contact)
= -***- Separator

Common abreviations

C, YES Yes -*-*, -*-- * ***
NO No -* ---
AS Wait *-*** (Sent as one letter. Answer with YES or C)
CQ "seek you", calling any station, -*-* --*-
SOS ***---*** international distress call.

Extensions to the Morse Code (nation or language dependent):

å  *--*-
ä  *-*-
à  *--*-
é  **-**
ch ----
ö  ---*
ü  **--
"  *-**-*
!  **--*

Conversation with morse code

The skill to have sensible conversations with morse is more than knowing just the alphabeth. 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 K
Calling s1, this is s2, listening
(Now we have a connection)

s1:

@
Bye.

s2:

@
Bye.

Stations weren't chatting a lot above, just testing a connection.