A call on line 2 completes when both switches are in position B. To
use both lines, the switches alternate between positions A and B.
When the switching rate is low, both transmissions become garbled and
unintelligible.
Increasing the switching speed clarifies the
transmission.
By increasing the switching speed to a rate higher
than
voice
frequencies,
the
switching
distortion
becomes
undetectable.
The circuit shown in figure 1-4 is a simplified 12-channel TDM
system.
The two switches rotate in synchronism and sample each
channel once during each revolution. The 12 samples are in each time
frame. By increasing the rotation speed above voice frequency, very
little distortion occurs and all 12 conversations are intelligible.
Figure 1-1.
Frequency division multiplexing
1-4
SS0016
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