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 in Baltimore is on display in the Library of Congress in Washington, D.C. In its original implementation, the Morse Code specification included the following: Various other companies and countries soon developed their own variations of the original Morse Code. Of special importance was one standard, originally created in Germany by Friedrich Clemens Gerke in 1848, which was simpler—it eliminated the long intra-character spaces and the two long dashes—but also included changes in the sequences for eleven of the letters and most of the numerals. The Gerke code had a distinct advantage for use on undersea telegraph cables. Cables suffer from