These notes have been prepared by G3IRM to give you some idea how coherent c.w. operates. As you all will know, morse code consists of dots and dashes arranged to represent letters, figures and punctuation marks. The basic element is the dot which has a predetermined length depending on the speed of transmission.
High speeds require short dots.
Hand sent morse code and for that matter code sent with semi-automatic and automatic keys is random in nature and, even if the characters are correctly sent, the spaces can vary considerably. The standard speed for coherent c.w. adopted by Ray Petit W7GHM when he designed the system was 12 words per minute. In actual fact it was the dot length which he decided should be fixed at 100 milliseconds. An element space was, therefore, also 100 milliseconds, a dash and character space were each equal to 300 milliseconds and all other spaces were multiples of the same 100 milliseconds. Coherent c.w. depends entirely on accurate timing based on the element length.