Jack Gibson

Morse Code & Telegraphy

Background Summary


Photo by Jack Gibson

      Electrical telegraphy was invented by Samuel Morse and his associates in 1836. It consisted of making coded letters into words with various short and long pulses of electricity transmitted over wires from one location to another. Morse’s coded letters evolved over the next 15 years or so into a standardized system of electrical pulsed dots, dashes, and spaces, which is essentially as we know it today. This coding system consists of 5 parts; a short pulse (dot), a longer pulse (dash), short gap or space between dots and dashes making up a letter, a longer space between letters, and longer yet space between words. The crude code receiver devices of those days made clicking or buzzing sounds in the same order as the pulses received which the receiving operator could translate in his head and write down on paper. About the dawn of the 20th Century, radio transmission of the pulses became known and made long distance transmission and reception easier and more efficient. (Morse code can also be sent and received by light blinks, touch, eye blinks, horns, or any audible sound maker over short distances in air and even longer underwater.)

     Pulsed dots and dashes are made by simply turning on and off the electricity with gaps or spaces in the correct sequence. This off & on switch is traditionally known as a telegraph “key.” With a key, the operator can mash down with his fingers on a knob to send (on), with a spring to return the knob up (off). The photo is of a World War II era military key (still in use); the operator’s knob is on the left.

     Morse code telegraphy rapidly came into worldwide use by the 1930s by commercial and military groups on land, through the air, on ships, under the sea (cables), and in aircraft. After more than a hundred years, it began fading out as computer and satellite technologies began to take over in the communications field. The last commercial and military Morse messages were sent in the last half decade of the 1990s. However, amateur radio (Ham) operators still use it for around-the-world shortwave radio communications. Morse is also still used in aviation navigation aids and some satellites use it to broadcast their identity.   (For more detail on the history and use of Morse code, see Wikipedia’s chapter titled Morse Code.)

Copyright © Jack Gibson 2013