Morse code

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 sentencess). Of course, Morse code is also a binary code, in that it is based on only two states -- on and off. Both views (dits/dahs/spaces vs. on and off) are correct.

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, 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 as American Morse code, was the version that was used to transmit the first telegraph message.

The code may be 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 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: 500 kHz

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

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. 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 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 (straight key)is still used by many amateurs, the use of semi- and fully-automatic electronic keyers (known as a "bug") is prevalent today. Computer software is also frequently employed to produce and decode Morse code RF signals.

A commercially manufactured paddle used in conjuction 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 the letter "a" inside the swirl appearing to be a "C")[1]. 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

Representation and timing

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):

.

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 characer, they are sent "run together"; that is, omitting the normal pauses that would occur if they were being sent as letters of text. They are normally represented in print by the letters with a ligating bar above them.

Although these are not really prosigns, an error may be indicated by some series of 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 -·-·· ch ---- é ··-·· ĝ --·-· ĥ -·--· ĵ ·---· ö ---· (also ø) ŝ ···-· ü ··-- (also ŭ) " ·-··-· ! ··--·

Commonly-used Morse code abbreviations

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 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 SMS Short message service 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 for any female) 73 Best regards 88 Love and kisses See also: Q code

Conversation with Morse code

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:
S2 DE S1 = GA DR OM UR RST 599 HR = QTH TIMBUKTU = OP IS MIKE HW? = + S2 DE S1 K
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?
S2:
S1 DE S2 = TNX FB RPRT DROM MIKE UR 558 = QTH HIMALAYA = NAME IS YETI = + S1 DE S2 K
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 = BEST 73 ES HPE CUAGN = + S2 DE S1 K
Okay, thanks dear Yeti for this conversation.
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. 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).

See also