Morse code most common letter in English, the letter "E", has the shortest code: a single dot. Because the Morse code elements are specified by proportion rather than specific time durations, the code is usually transmitted at the highest rate that the receiver is capable of decoding. The Morse code transmission rate ("speed") is specified in "groups per minute", commonly referred to as "words per minute". Morse code is usually transmitted by on-off keying of an information carrying medium such as electric current, radio waves, visible light or sound waves. The current or wave is present during time period of the dot
American Morse code Most radio operators used the version of the Code that they were most familiar with—the American Morse Code in the United States, and Continental Morse in Europe. However, because of the long range of radio signals, a single international standard was needed, especially for seagoing vessels. At the Radiotelegraphic Convention meeting in London in 1912, the section of the Convention covering "Transmission of Radiograms" included the statement that "The signals to be employed are those of Morse International Code." Even after this, the original Morse Code continued to be used throughout much of the United States. American Morse remained the