Radiotelegraphy

Wireless telegraphy is the transmission of electric telegraphy signals without wires (wirelessly). It is now used as a historical term for early radio telegraphy systems which communicated with radio waves, although when the term originated in the late 19th century it was also used for a variety of other experimental techniques for communicating telegraphically without wires, such as photoelectric and induction telegraphy.

Wireless telegraphy came to mean Morse code transmitted by radio waves (electromagnetic waves), initially called "Hertzian waves", discovered by Heinrich Hertz in 1886. The first practical wireless telegraphy transmitters and receivers were developed by Guglielmo Marconi beginning in 1895. By 1910 communication by Hertzian waves was universally referred to as "radio", and the term wireless telegraphy has been largely replaced by the more modern term "radiotelegraphy". The transmission of sound (radiotelephony) began to displace wireless telegraphy by the 1920s for many applications, making possible radio broadcasting. Wireless telegraphy continued to be used for private point-to-point business, governmental, and military communication, such as telegrams and diplomatic communications, and evolved into radioteletype networks. Continuous wave (CW) radiotelegraphy is regulated by the International Telecommunication Union (ITU) as emission type A1A.

Today, due to more modern text transmission methods, Morse code radiotelegraphy for commercial use has become obsolete. On shipboard the computer and satellite linked GMDSS system has largely replaced Morse as a means of communication. Telegraphy is taught on a very limited basis by the military. A CW coastal station, KSM, still exists in California, run primarily as a museum by volunteers, and occasional contacts with ships are made. Radio beacons, particularly in the aviation service, but also as "placeholders" for commercial ship-to-shore systems, also transmit Morse but at very slow speeds.

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