Morse code is a form of textual transmission as a series of on-off tones, lights, or clicks that are interpreted by a skilled listener. International Morse Code encodes the Roman alphabet, Arabic numerals, and a small set of punctuation as standardized sequences of short and long “dots” and “dashes”. Since many non-English languages have more than 26 letters there are extensions to the Morse alphabet.
The speed of Morse code is measure in WPM. A dot is one “on” element followed by an off while a dash is three “ons” and one “off. Every character is a combination of dots and dashes. The shorter sequences are used for commonly used English letters.
Samuel F. B. Morse’s electric telegraph originally had a different code created for it in the early 1840’s. Later Morse code was created and used extensively for early radio communication. Most international communication used Morse code on telegraph lines and radio circuits. Morse code was poorly suite for computer reception so machine to machine communication generally used frequency shift keying or phase shift keying.
Although no longer requiring licensing in most countries many pilots and air traffic controllers are familiar with Morse code. Morse is often used in place of voice communications for sending automated digital data. Morse is also one of the simplest and versatile methods for telecommunication and is often used for emergency signals.
In 1844, a system for telegraphy was first used. It made indentations on a paper tape when currents were received. Morse code was invented to translate the indentations marked on the paper tape. The earliest part of the code was meant to only translate numerals; however, Alfred Vail expanded it to include letters and special characters.
In the 1920’s Morse code was used on a regular basis for aviation. The first noted use on a plane was when the Southern Cross had a crewmen was a radio operator who communicated with ground stations via radio telegraph. In the 1930’s both civilian and military pilots were required to know how to use Morse Code. During World War II radio telegraphy used Morse Code and carried messages between various Navys. It was also used by airplanes during the war. Moving units within the army also would not have been efficient without the use of radio telegraphy. Up until 1999 Morse code was an international standard for maritime communications.
Morse code has been used longer than any other electrical coding system. The code has evolved from what it originally was. However, now Morse code is seldom used except in historical re-enactments. Up until 2003 amateur radio operators were required to be licensed in Morse Code.
Due to the use of an on-off keyed radio signal Morse code requires less complex transmission equipment than other forms of radio communication. It is usually received as a high pitched audio tone so transmissions are easier to copy than voice through noisy frequencies. Also since they are transmitted with a very concentrated power it is possible to use narrow receiver filters that suppress or eliminate interference. Since the relative speed of Morse Code is relatively slow many abbreviations were developed to speed communication.