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FACSIMILE SYSTEM
3.4
Line Signal Monitor
In the
the telephone side in the same way as in a standby state so that the tele-
phone line is connected directly to the telephone. However, when the call-
ing party is a facsimile, the CML relay must be switched to facsimile for
reception, and so the CML relay is switched to the facsimile side according
to the signals arriving from the telephone line.
For this reason, a circuit (line signal monitor circuit) is made between the
CML relay and the H relay for monitoring the signals (CNG or DTMF)
that arrive from the telephone line. In the answering machine connection
mode, the signals are monitored to enable facsimile communications
immediately when the other party is a facsimile.
The line signal monitor circuit is divided into a primary side and secondary
side with a transformer provided as the boundary in the same way on the
facsimile side.
6–10
answering machine connection
"We are unavailable at the
moment to take your call."
Off-hook
detection
B
circuit
Answering machine
message currently
being played back
CNG
Exchange
Fig. 6-9 Line Signal Monitor Circuit
mode, the CML
CNG
CI detection
circuit
H relay
CNG
Line signal monitor circuit
CML relay
relay
is switched to
MODEM
To 2-wire/4-wire
conversion circuit
NCU board
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