Panasonic DX-2000 Service Manual page 256

Dial Pulse Generator
The circuit consists of the CML relay, PLS relay and their peripheral circuits. This circuit generates dial pulses. The CPU on the
FCB PC Board controls all dial pulse generation sequences.
DZZSP58025 (IC60). The status of the relays during dialing is shown below. When the absence of the terminating message is
confirmed by the Off-Hook detector, the CPU turns CML relay ON to develop loop status (DC loop). After a few seconds, the
CPU turns the PLS relay On and Off to generate dial pulses, making and breaking the loop.
Dial Pulse
CML Relay
PLS Relay
Line release
Line status
DTMF Tone Generator
The circuit is incorporated in the MODEM on the FCB PC Board. The DTMF tone is conveyed to the telephone line using the
same route as the facsimile signal. The DTMF tone selection is controlled by the CPU. The relay status during dialing is shown
below.
DTMF Tone
PLS Relay
CML Relay
Line release
Line status
break
make
break
make
Speech
condition
break
Prepause
make
break
make
break
make
First
Speech
condition digit
Prepause
break
make
It turns relay CML and PLS ON and OFF through the
First Speech
digit condition
Inter-digit
pause
Speech
condition
Inter-digit
pause
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Second
Speech
digit condition
Second
Speech
digit condition
DTMF signal