Morse Code - Wikipedia, the free encyclopedia file:///H:/optical/Morse_Code.htm Morse Code From Wikipedia, the free encyclopedia. Morse Code is a method for transmitting information, using standardized sequences of short and long marks or pulses -- commonly known as "dots and dashes" -- for the letters, numerals and special characters of a message. Originally created for Samuel Morse's electric telegraph in the mid-1830s, it was also extensively used for early radio communication beginning in the 1890s. However, with the development of more advanced communications technologies, the use of Morse Code is now largely obsolete, although it is still employed for a few specialized purposes, including navigational radio beacons, and by CW (continuous wave) amateur radio operators. Morse Code can be transmitted in a number of ways: originally as electrical pulses along a telegraph wire, but also as an audio tone, as a radio signal with short and long pulses or tones, or as a mechanical or visual signal (e.g. a flashing light). Because Morse Code is transmitted using just two states -- on and off -- it was an early form of a digital code. International Morse Code is composed of six elements: 1. short mark or dot (·) 2. longer mark or dash (-) 3. intra-character gap (between the dots and dashes in a character) 4. short gap (between letters) 5. medium gap (between words) 6. long gap (between sentences) However, the variable length of the Morse characters made it hard to adapt to automated communication, so it was largely replaced by more standardized formats, including the Baudot code and ASCII. 1922 Chart of the Morse Code Letters and Numerals What is called Morse Code today actually differs somewhat from what was originally developed by Morse and his assistant, Alfred Vail. In 1848 a refinement of the code sequences, including changes to eleven of the letters, was developed in Germany and eventually adopted as the worldwide standard as "International Morse". Morse's original code specification, largely limited to use in the United States, became known as Railroad or American Morse code, and is now very rarely used. The short and long elements of Morse Code have traditionally been referred to as "dots" and "dashes". However, a later convention developed which reflects the sound of audio transmissions, and refers to dashes as "dah", and dots as "di", unless the dot is the final symbol in the character, in which case it is voiced as "dit". 1 of 12 3/28/2006 4:30 PM Morse Code - Wikipedia, the free encyclopedia file:///H:/optical/Morse_Code.htm Contents 1 Development 2 Modern International Morse code 3 Morse code as an assistive technology 4 Representation and timing 5 Letters, numbers, punctuation, prosigns 5.1 Numbers 5.2 Common punctuation 5.3 Alternate display of more common characters for the international code 5.4 Special symbols (prosigns) 5.5 Non-English extensions to the Morse code 6 Commonly-used Morse code abbreviations 7 Conversation in Morse code 8 See also 9 External links 9.1 Morse code translators and software Development Beginning in the mid-1830s, Samuel Morse and Alfred Vail developed an electric telegraph, which used electrical currents to control an electromagnet that was located at the receiving end of the transmission wire. The technological limits of the time made it impossible to print individual characters in a readable form, so the inventors had to devise an alternate method of communication. Beginning in 1837, William Cooke and Charles Wheatstone operated electric telegraphs in England, which also controlled electromagnets in the receivers, however, in their systems needle pointers were rotated in order to indicate the characters being sent. In contrast, Morse and Vail's initial telegraph system, which first went into operation in 1844, marked a paper tape -- when an electrical current was transmitted, the receiver's electromagnet rotated an armature, so that it began to scratch a moving tape, and when the current was removed the receiver retracted the armature, so that portion of the tape was left unmarked. The Morse Code was developed so that operators could translate the indentions marked on the paper tape into text messages. Initially, Morse had planned to only transmit numerals, and use a dictionary to look up each word according to the number which had been sent. However, the code was expanded to include letters and special characters, so it could be used for more complete messages. The shorter marks were called "dots", and the longer ones "dashes", and the letters most commonly used in the English language were assigned the shortest sequences. In the original telegraphs, the armature in the receiver made a clicking noise as it moved into and out of position for marking the tape. Operators soon learned to directly read the clicks as the beginning and end of the dots and dashes, meaning that it was no longer necessary to use the tape. When Morse Code was adopted to radio, the dots and dashes were normally sent as short and long tones. Morse messages are generally transmitted by a hand-operated devices such as a telegraph key, so there are some variations introduced by the skill of the sender and receiver -- more experienced operators can send and receive at faster speeds. In general, any code representing written symbols as variable length signals can be called a Morse code, but the term is used specifically for the two kinds of Morse code used for the English alphabet and associated symbols. Telegraph companies charged based on the length of the message sent. Elaborate commercial codes were developed that encoded common phrases in five-letter groups that were sent as single words. Examples: BYOXO ("Are you trying to crawl out of it?"), LIOUY ("Why do you not answer my question?"), and AYYLU ("Not clearly coded, repeat more clearly."). The letters of these five-letter code words were sent individually using Morse code. In computer networking terminology one would say the commercial code is layered on top of Morse code, which in turn is layered on top of binary 2 of 12 3/28/2006 4:30 PM Morse Code - Wikipedia, the free encyclopedia file:///H:/optical/Morse_Code.htm code, which in turn is layered on top of a physical telegraph wire. Still in use in Amateur Radio are the Q code and Z code; they were and are used by the operators themselves for service information like link quality, frequency changes, and telegram numbering. When considered as a standard for information encoding, Morse code had a successful lifespan that has not yet been surpassed by any other electronic encoding scheme. Morse code was used as an international standard for maritime communication until 1999 when it was replaced by the Global Maritime Distress Safety System. When the French navy ceased using Morse code in 1997, the final message transmitted was "Calling all. This is our last cry before our eternal silence." See also: international distress frequency Recently a few widely publicized speed contests have been held between expert Morse code operators and expert cellphone SMS text messaging users (see external links). Morse code has consistently won the contests, leading to speculation that cellphone manufacturers may eventually build a Morse code interface into cellphones. The interface would automatically translate the Morse code input into text so that it could be sent to any SMS capable cellphone so therefore the receiver of the message need not know Morse code to read it. Other speculated applications include taking an existing assistive application of Morse code and using the vibrating alert feature on the cellphone to translate SMS messages to Morse code for silent, hands free "reading" of the incoming messages. Several cellphones already have informative audible Morse code ring tones and alert messages, for example: many Nokia cellphones have an option to beep SMS in Morse code when it receives an SMS text message. These kinds of innovations could lead to a Morse code revival. There are third party applications already available for some cellphones that allow Morse code input for sending SMS (see external links). Modern International Morse code The Modern International Morse code was invented by Friedrich Clemens Gerke in 1848 and used for the telegraphy between Hamburg and Cuxhaven in Germany. After some minor changes in 1865 it has been standardised at the International Telegraphy congress in Paris (1865), and later normed by the ITU as International Morse code. International Morse code is still in use today, although it has become almost exclusively the province of amateur radio operators. Until 2003 the International Telecommunications Union (ITU) mandated Morse code proficiency as part of the amateur radio licensing procedure throughout the world. In some countries, certain parts of the amateur radio bands are still reserved for transmission of Morse code signals only. Since Morse relies on only an (on-off keyed) radio signal, it requires less complex equipment than other forms of radio communication, and it can be used in very high noise / low signal environments. It also requires less bandwidth than voice communications, typically 100-150 Hz, compared to the roughly 4000 Hz of single-sideband voice. The extensive use of pro-signs, Q codes, and restricted format of typical messages facilitates communication between amateur radio operators who do not share a common mother tongue and would have great difficulty in communicating using voice modes. Morse code is also very popular among QRP operators for enabling very long distance, low-power communication. Readability can be sustained by trained operators even though the signal is only faintly readable. This level of "penetration" is due to the fact that all transmitted energy is concentrated in a very small bandwidth making the use of a narrow receiver bandwidth practical.