Morse code facts for kids

Chart of the Morse code letters and numerals

Morse code is still used on ships, using lights

Morse code is a type of code that is used to send telegraphic information using rhythm.

Morse code is named after Samuel Morse, who helped invent it. It is not used as much today as it was in the 19th and 20th centuries. Teletypewriters were invented in the early 20th century with their own codes and gradually replaced Morse code. Other types of technology that are easier to use for communication became even more common. However, some people still use Morse code to communicate on amateur radio.

There are different types of Morse code for different countries.

There are three different symbols in Morse code; there's a short one, usually called 'dit', a long one, called 'dah', and the pause. A dah is three times as long as a dit, and the pause has the same length as the dit.

History

Morse code receiver that records on paper tape

The American artist Samuel Morse, the American physicist Joseph Henry, and mechanical engineer Alfred Vail developed an electrical telegraph system. The simple "on or off" nature of its signals made it desirable to find a method of transmitting natural language using only electrical pulses and the silence between them. Around 1837, Morse therefore developed such a method, an early forerunner to the modern International Morse code.

The Morse 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. Morse code was developed so that operators could translate the indentations marked on the paper tape into text messages.

In his earliest design for a code, Morse had planned to transmit only numerals, and to use a codebook to look up each word according to the number which had been sent. However, the code was soon expanded by Alfred Vail in 1840 to include letters and special characters, so it could be used more generally. Vail estimated 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, New Jersey. The shorter marks were called "dots" and the longer ones "dashes", and the letters most commonly used were assigned the shortest sequences of dots and dashes. This code, first used in 1844, was what later became known as Morse landline code, American Morse code, or Railroad Morse, until the end of railroad telegraphy in the U.S. in the 1970s.

Representation, timing, and speeds

International Morse code encodes the 26 basic Latin letters A to Z, one accented Latin letter (É), the Arabic numerals, and a small set of punctuation and procedural signals (prosigns). There is no distinction between upper and lower case letters. Each Morse code symbol is formed by a sequence of dits and dahs. The dit duration can vary for signal clarity and operator skill, but for any one message, once established it is the basic unit of time measurement in Morse code. The duration of a dah is three times the duration of a dit (although some telegraphers deliberately exaggerate the length of a dah for clearer signalling). Each dit or dah within an encoded character is followed by a period of signal absence, called a space, equal to the dit duration. The letters of a word are separated by a space of duration equal to three dits, and words are separated by a space equal to seven dits.

International Morse code is composed of five elements:

1. short mark, dot or dit (  ▄ ): "dit duration" is one time unit long
2. long mark, dash or dah (  ▄▄▄ ): three time units long
3. inter-element gap between the dits and dahs within a character: one dot duration or one unit long
4. short gap (between letters): three time units long
5. medium gap (between words): seven time units long (formerly five)

Applications for the general public

Representation of Morse code SOS

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. The SOS signal is not sent as three separate characters; rather, it is a prosign SOS, and is keyed without gaps between characters.

Images for kids

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  Single needle telegraph instrument

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  Telegraph key and sounder. The signal is "on" when the knob is pressed, and "off" when it is released. Length and timing of the dits and dahs are entirely controlled by the telegraphist.

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  A U.S. Navy Morse Code training class in 2015. The sailors will use their new skills to collect signals intelligence.

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  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.

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  Cayo Largo Del Sur VOR-DME.

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  Vibroplex brand semiautomatic key (generically 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 single 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.

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  Graphical representation of the dichotomic search table. The graph branches left for each dot and right for each dash until the character representation is exhausted.

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  Scout movement founder Baden-Powell's mnemonic chart from 1918

See also

In Spanish: Código morse para niños