"morse code"
 Morse Code is a way of transmitting information via use of clicks, lights and on-off tones which can be deciphered by a skilled receptor or with special equipment. The International Morse Code encodes signals in the form of dots and dashes and was first developed by Samuel Morse in 1836 so that telegraph operators could decode indentations marked on strips of paper tape into text messages.

Today it remains hugely popular with amateur radio operators.