In telecommunications, frequency-change signaling is a telegraph signaling method in which one or more particular frequencies correspond to each desired signaling condition of a telegraph code. The transition from one set of frequencies to the other may be a continuous or a discontinuous change in the frequency or phase.
See also Frequency-shift keying Frequency modulation
References
This article incorporates public domain material from Federal Standard 1037C. General Services Administration. Archived from the original on 2022-01-22. (in support of MIL-STD-188).