audio-frequency shift modulation

audio-frequency shift modulation

[′ȯd·ē·ō ¦frē·kwən·sē ‚shift mäj·ə′lā·shən]
(communications)
System of facsimile transmission over radio, in which the frequency shift required is applied through an 800-hertz shift of an audio signal, rather than shifting the radio transmitter frequency; the radio signal is modulated by the shifting audio signal, usually at 1500 to 2300 hertz.
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