Dial Pulse Generator
The circuit consists of the CML relay, PLS relay and their peripheral circuits. This circuit generates
dial pulses. The CPU PC Board controls all dial pulse generation sequences. It turns relay CML and
PLS ON and OFF through the DZZSP58025. 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
break
CML Relay
make
break
PLS Relay
make
SpeechFirstSpeechSecondSpeech
conditiondigitconditiondigitcondition
Line release
break
PrepauseInter-digit
pause
Line status
make
DTMF Tone Generator
The circuit is incorporated in the MODEM 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
break
PLS Relay
make
break
CML Relay
make
SpeechFirstSpeechSecondSpeech
conditiondigitconditiondigitcondition
Line release
Inter-digit
Prepause
pause
breakDTMF signal
Line status
make
17 |
ACEC
PANASONIC
