Advertisement
the transmission signal would return to the reception amplifier via
C30 and R31. Here, the signal output from CN1 pin (11) passes
through C30, C36 and R39 and enters the amplifier IC2 pin (5).
This is used to cancel the return portion of the transmission
signal. This is the side tone circuit.
5.9. ITS (Integrated telephone System) and MONITOR SECTION
5.9.1. GENERAL
During the monitor operation, the speaker output passes through the power amplifier (IC1)
[Analog board]. / The DTMF signal is output from the modem (IC1: digital board). The alarm
tone, the key tone, bell tone, and beep are output from gate array IC1 (digital board). During a
pulse dial operation, the monitor tone is output from gate array IC1.
5.9.2. MONITOR CIRCUIT
1. Function
This is the function when you are not holding the handset and can
hear the caller's voice from the line.
2. Circuit Operation
(Monitor Signal Path)
Signals received from the telephone line are output through at the
speaker via the following path.
Refer to
CHECK SHEET
5.9.3. HANDSET CIRCUIT
1. Transmission signal
Refer to 2.3.4.4. Analog Board Section
2. Reception Signal
Refer to
CHECK SHEET
5.9.4. MONITOR CIRCUIT
1. DTMF Monitor
()
()
157
Advertisement
