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 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”, 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 the words are separated by a space equal to seven dots. The dot duration is the basic unit of time measurement in code transmission. 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. 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.
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.
Representation, timing and speeds
International Morse code is composed of five elements:
short mark, dot or “dit” (·) — “dot duration” is one time unit long
longer mark, dash or “dah” (–) — three time 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 time units long
medium gap (between words) — seven time units long
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, audible or visual signal (e.g. a flashing light) using devices like an Aldis lamp or a heliograph, a common flashlight, or even a car horn. Some mine rescues have used pulling on a rope – a short pull for a dot and a long pull for a dash.
Morse code is transmitted using just two states (on and off). Historians have called it the first digital code. Strictly speaking it is not binary, as there are five fundamental elements. 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 experienced 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. The words PARIS and 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. 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.
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
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) –·–· ––– –·· ·
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.
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 the Heathkit version, on-air use is not yet universal as some amateur radio operators in North America and the Caribbean 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 ITU has never codified formal Morse Code representations for currencies as the ISO 4217 Currency Codes are preferred for transmission.
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”).
Keyboard AT @
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”. 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.
Meaning Code Meaning Code Meaning Code
Wait · – · · · Error · · · · · · · · Understood · · · – ·
Invitation to transmit – · – End of work · · · – · – Starting Signal – · – · –
How is morse code used today?
Morse code was once widely used World over by almost everyone needing distant communication. Military, overseas shipping and the railroad relied on Morse code to provide reliable messages via wires. After the invention of radio during the first years of the 1900s, communication became more widespread and predictable. Industries relied on it to send simple and rapid messages to their distant clients and employees.
Communication today relies upon satellites, a complex grid and advanced technology to speed messages rapidly World-wide. The internet has increased information flow and ease of contact in almost unimaginable ways. However, old technology has a way of creeping back, since it is simple, relatively inexpensive and does not depend on the fragile grid systems of modern technology. Morse code operators stand ready to help in dire emergencies, grid failures, or war!
At Code Quick, we have always used an analogy to the old farm “out house.” The technology might not be up to date, but it is certainly comforting to know there is one to fall back on if advanced plumbing fails.
Consider the following:
Amateur radio operators use Morse code extensively for contests, during which rapid connections are imperative. Morse code know as continuous wave transmissions or CW, requires a small footprint and therefore is readable when pileups occur on radio bands. The larger the amount of data to be transferred, the larger the amount of bandwidth required. Radios can be constructed cheaply without modulation and run much less power than with more sophisticated equipment.
Navigation beacons help airline pilots find and maintain proper headings even today.
Flashing light Morse even from a flashlight may be read several miles away for a lost sailor or hunter. Countless snowstorm rescues have been recorded by stranded drivers flashing an SOS signal on a flashing light. Mirrors accomplish the same thing during the day. The user directs a mirrored sun reflection and then blocks it with his other hand or piece of cardboard flashing out the Morse code signal.
Medical uses allow the severely handicapped person to tap or blink out a message that can now be ready by computers, giving new hope and meaning to life for sufferers.
A new method for using Morse code involves cell phones and text messages entered from an iambic keyer on the cell phone face. It seems that experienced Morse code operators can enter the text much faster than a QUERTY keyboard operator and can do it without looking at the keyboard.
Who knows how brilliant minds will conceive of ways to use this simple technology in the future. In the mean time, knowing code might just allow you to survive, especially in times of catastrophe or national emergency.