Canon fax basic 2000 サービスマニュアル

A–26

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.

Fig. A-24   Phase Jitter

Original waveform

Waveform
phase jitter

Amplitude

Time