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October,2008.

Continuous wave

CW - Modern International Morse Code
Morse code links

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. 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. A narrow bandwidth receiver uses filters to exclude interference on frequencies close to the desired frequency. Concentrating the transmitted energy in a small bandwidth gives the signal a "spectral brightness" that is much higher than the average natural noise (but see also spread spectrum).

In the United States until 1991, a demonstration of the ability to send and receive Morse code at 5 words per minute (WPM) was required to receive an FCC amateur radio license. Demonstration of this ability is still required for the privilege to use the HF bands. Until 1999, proficiency at the 20 WPM level was required to receive the highest level of amateur license (Extra Class); effective April 15, 2000, the FCC reduced the Extra Class requirement to 5 WPM.

The World Radiocommunication Conference of 2003 (WRC-03) made optional the international Morse code requirement for amateur radio licensing. Although the requirement remains on the books in the US, Canada, and elsewhere, some countries are working to eliminate the requirement entirely.

Amateur and military radio operators skilled in Morse code can often understand ("copy") code in their heads at rates in excess of 40 WPM. Although the traditional telegraph key (straight key)is still used by many amateurs, the use of semi- and fully-automatic electronic keyers (known as "bugs") is prevalent today. Computer software is also frequently employed to produce and decode Morse code RF signals.

A commercially manufactured paddle used in conjunction with an electronic keyer to generate high-speed Morse code.

As of 2004 commercial radiotelegraph licenses are still being issued in the United States by the Federal Communications Commission. Designed for shipboard and coast station operators, they are awarded to applicants who pass written examinations on advanced radio theory and show 20 WPM code proficiency (this requirement is waived for "old" Extra Class licensees). However, since 1999 the use of satellite and very high frequency maritime communications systems (GMDSS) have essentially made them obsolete.

On May 24, 2004, the 160th anniversary of the first telegraphic transmission, the ITU added the "@" (the "commercial at" or "commat") character to the Morse character set and is the digraph "AC" (probably to represent the letter "a" inside the swirl appearing to be a "C"). The new character facilitates sending electronic mail addresses by Morse code and is notable since it is the first official addition to the Morse set of characters since World War I.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "CW".

Morse code links

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