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Chart of the Morse code 26 letters and 10 numerals [1]. This Morse key was originally used by Gotthard railway, later by a shortwave radio amateur [2]. Morse code is a telecommunications method which encodes text characters as standardized sequences of two different signal durations, called dots and dashes, or dits and dahs.
SOS is a Morse code distress signal ( ), used internationally, originally established for maritime use.In formal notation SOS is written with an overscore line (SOS), to indicate that the Morse code equivalents for the individual letters of "SOS" are transmitted as an unbroken sequence of three dots / three dashes / three dots, with no spaces between the letters. [1]
As long as the telegraph key was pressed, the transmitter would produce a string of transient pulses of radio waves which repeated at an audio rate, usually between 50 and several thousand hertz. [33] In a receiver's earphone, this sounded like a musical tone, rasp or buzz. Thus the Morse code "dots" and "dashes" sounded like beeps.
Morse code mnemonics are systems to represent the sound of Morse characters in a way intended to be easy to remember. Since every one of these mnemonics requires a two-step mental translation between sound and character, none of these systems are useful for using manual Morse at practical speeds.
Acoustic telegraphy (also known as harmonic telegraphy) was a name for various methods of multiplexing (transmitting more than one) telegraph messages simultaneously over a single telegraph wire by using different audio frequencies or channels for each message. A telegrapher used a conventional Morse key to tap out the message in Morse code ...
MCW can be generated by any AM or FM radio transmitter with audio input from an audio oscillator or equivalent audio source. [1] [2] When an SSB transmitter is modulated by Morse code of only a single audio frequency, the resulting radio frequency emission is J2A or J2B and therefore is CW by definition, not MCW. [3]
The procedure signs below are compiled from the official specification for Morse Code, ITU-R M.1677, International Morse Code, [1] while others are defined the International Radio Regulations for Mobile Maritime Service, including ITU-R M.1170, [8] ITU-R M.1172, [4] and the Maritime International Code of Signals, [5] with a few details of their ...
The following telegraph code table is adapted from one given by Ashok Kelkar, [2] where the Latin letters are encoded as per the International Morse code standard. Some variations on this code exist, [3] and there have been some attempts to introduce other telegraph codes either to improve efficiency or to apply to more Indian languages.