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
Spelling alphabet to 1959. For the 1959–Present phonetics, the underlined syllable of each letter word should be emphasized, and each syllable of the code words for the figures (1969–Present) should be equally emphasized. After WWII, the major work in producing a better spelling alphabet was conducted by the ICAO, which was subsequently adopted in modified form by the ITU and IMO. Its development is related to these various international conventions on radio, including: The ICAO Radiotelephony Alphabet is defined by the International Civil Aviation Organization for international aircraft communications. Defined by the Association of Public-Safety Communications Officials-International. The APCO first suggested that