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FDM
FDM stands for Frequency Division Multiplex.
This is a multiplex system in which the available transmission bandwidth
of a transmission line is divided by frequency into narrow bands. By this
method, carrier waves of differing frequencies are modulated on the signal
wave, and their single sidebands are arranged along the frequency axis.
There is another multiplex method TDM (Time Division Multiplex) in
which one transmission line is used alternately for time sharing.
(8) Phase jitter
"Phase jitter" presents the fluctuation of the signal phase. Phase jitter
occurs when the signal is modulated with phase modulation (PM) or fre-
quency modulation (FM) by some cause.
Phase jitter does not cause any special problems in telephone conversa-
tions. In G3 facsimile transmission, however, lines may be missed.
A–26
Original waveform
Waveform
phase jitter
Fig. A-24 Phase Jitter
Time
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