A fax demodulator is a device used to intercept fax messages by listening in on a
telephone line or radio signal.
A typical (
Group III) fax transmission requires a two-way conversation between two
modems (that is, each participant must both transmit and receive). Each modem may be part of a “fax machine” incorporating an image scanner and a printer. A
demodulator
Demodulation is extracting the original information-bearing signal from a carrier wave. A demodulator is an electronic circuit (or computer program in a software-defined radio) that is used to recover the information content from the modulated ...
can only be used to observe a conversation between two fax modems, usually to record the image transmitted. It cannot be used to receive a fax transmission in the usual sense, because a sending modem cannot transmit an image without first negotiating a connection with a receiving modem.
References
Communication circuits
Fax
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