Toa EXES-6000, Operating And Troubleshooting

Page: 36 / 60

In this instance, the voice switch (A) is ON. We
will explain why it is so.
Fig. 36 Control Section of Voice Switch (A)
In Fig. 36, the voice signal that passed through
HPF takes two courses: one goes to the voice
switch and the other to the comparator (A). The
comparator (A) compares the signal strength
between the signal from station (A) and one from
the mixing point (A), and provides "H" to "J"
input of Flip-flop (A) if the signal level from station
(A) is higher. In this event, no signal appears at
the mixing point (A) because no other stations
than station (A) are speaking. That is, the "J"
input of Flip-flop (A) is "H" and so is the "Q"
output, thus causing the voice switch (A) to be
ON. In this event, since the "Q" output is
connected to the "K" inputs of other Flip-flops (B)
to (D), these "K" inputs all become "H" and the
"Q" outputs of Flip-flops (B) to (D) are made "L".
As a result, voice switch (A) alone turns on and
other voice switches (B) to (D) are off.
Consider another example where both stations
(A) and (D) are speaking. (See Fig. 37).
2. Example when Two Station are in Conference
Fig. 37 Control Section of Voice Switch (D)
The voice signal from station (D) which passed
through HPF is transmitted to both voice switch
(D) and comparator (D). At the same time, the
voice signal from station (A) that appears at the
mixing point (D) is sent to the comparator (D). The
comparator (D) compares the signal strength
between these signals from both stations. If the
signal level from station (D) is higher, the voice
switch (D) turns on and the signal flows from
station (D) to stations (A), (B) and (C).
To sum up, when the conference function (CL
unit) is used, only one of the four voice switches
is activated just as in the case of hands-free to
hands-free conversation mode. The exceptions
are that the CL unit has no side tone circuit and
that the number of links corresponding to the DL
unit is two.
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