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A '''damped wave''' is an [[Electromagnetic radiation|electromagnetic wave]] whose [[amplitude]] of [[oscillation]] decreases with time, eventually going to zero. This term also refers to an early method of [[radio transmission]] produced by [[spark gap transmitter]]s, which consisted of a series of damped waves. Information was carried on this signal by [[telegraphy]], turning the transmitter on and off ([[on-off keying]]) to send messages in [[Morse code]]. Damped waves were the first practical means of radio communication, used during the [[wireless telegraphy]] era which ended around 1920. In [[radio engineering]] it is now generally referred to as "Class B" emission. However, such transmissions have a wide [[Bandwidth (signal processing)|bandwidth]] and generate electrical "noise" ([[electromagnetic interference]]) which interferes with other radio transmissions.
A '''damped wave''' is an [[Electromagnetic radiation|electromagnetic wave]] whose [[amplitude]] of [[oscillation]] decreases with time, eventually going to zero. This term also refers to an early method of [[radio transmission]] produced by [[spark gap transmitter]]s, which consisted of a series of damped waves. Information was carried on this signal by [[telegraphy]], turning the transmitter on and off ([[on-off keying]]) to send messages in [[Morse code]]. Damped waves were the first practical means of radio communication, used during the [[wireless telegraphy]] era which ended around 1920. In [[radio engineering]] it is now generally referred to as "Class B" emission. However, such transmissions have a wide [[Bandwidth (signal processing)|bandwidth]] and generate electrical "noise" ([[electromagnetic interference]]) which interferes with other radio transmissions.


There is currently an international prohibition against the use of Class B, damped wave emission.<ref name="FCC">{{cite web
There is currently an international prohibition against the use of Class B, damped wave emission.<ref>{{cite book
| last = Siwiak,
| first = Kazimierz
| authorlink =
| coauthors = Debra McKeown
| title = Ultra-wideband radio technology
| publisher = John Wiley and Sons
| date = 2004
| location = USA
| pages = 15
| url = http://books.google.com/books?id=SW1hJpjZbDwC&pg=PA15&lpg=PA15
| doi =
| id =
⚫
| isbn = 0470859318}}</ref> This prohibition forms part of the [[International Telecommunication Union]] regulations and is a throwback to the days when spark gap transmitters were employed. The prohibition against Class B emissions was intended to prevent the generation of wasteful radio frequency energy and the use of inefficient transmission techniques. However, ironically there is no longer a clear definition of a Class B, damped wave emission.<ref name="FCC">{{cite web
| last =
| last =
| first =
| first =
Line 13: Line 26:
| format =
| format =
| doi =
| doi =
| accessdate = 2010-03-04}}</ref>
⚫
| accessdate = 2010-03-04}}</ref> This prohibition forms part of the [[International Telecommunication Union]] regulations and is a throwback to the days when spark gap transmitters were employed. The prohibition against Class B emissions was intended to prevent the generation of wasteful radio frequency energy and the use of inefficient transmission techniques. However, ironically there is no longer a clear definition of a Class B, damped wave emission.<ref name="FCC" />


== References ==
== References ==

Revision as of 20:19, 5 March 2010

A damped wave is an electromagnetic wave whose amplitude of oscillation decreases with time, eventually going to zero. This term also refers to an early method of radio transmission produced by spark gap transmitters, which consisted of a series of damped waves. Information was carried on this signal by telegraphy, turning the transmitter on and off (on-off keying) to send messages in Morse code. Damped waves were the first practical means of radio communication, used during the wireless telegraphy era which ended around 1920. In radio engineering it is now generally referred to as "Class B" emission. However, such transmissions have a wide bandwidth and generate electrical "noise" (electromagnetic interference) which interferes with other radio transmissions.

There is currently an international prohibition against the use of Class B, damped wave emission.[1] This prohibition forms part of the International Telecommunication Union regulations and is a throwback to the days when spark gap transmitters were employed. The prohibition against Class B emissions was intended to prevent the generation of wasteful radio frequency energy and the use of inefficient transmission techniques. However, ironically there is no longer a clear definition of a Class B, damped wave emission.[2]

References

  1. ^ Siwiak,, Kazimierz (2004). Ultra-wideband radio technology. USA: John Wiley and Sons. p. 15. ISBN 0470859318. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)CS1 maint: extra punctuation (link)
  2. ^ "Notice of Inquiry, ET Docket No. 98-153: Revision of Part 15 of the Commission's Rules Regarding Ultra-Wideband Transmission Systems". US Federal Communications Commission. September 1, 1998. Retrieved 2010-03-04. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)

See also

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