Frequency-exchange signaling
In telegraphy, frequency-exchange signaling or two-source frequency keying is frequency-change signaling in which the change from one significant condition to another is accompanied by decay in amplitude of one or more frequencies and by buildup in amplitude of one or more other frequencies.
Frequency-exchange signaling applies to supervisory signaling and user-information transmission.
See also
References
This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C" (in support of MIL-STD-188).
This article is issued from Wikipedia - version of the 7/23/2012. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.