Panasonic UF-580 Service Manual page 208

Dial Pulse Generator
The Dial Pulse Generator consists of a CML relay, a DC hold circuit, a dial pulse generate circuit and their
peripheral circuits. The generator generates dial pulses. The CPU on the SC PC Board controls all dial
pulse generation sequences. When the absence of the terminating message is confirmed by the Off-Hook
detector in DAA(IC23), the CPU turns the CML relay ON and the dial pulse generate circuit ON through
DAA 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. The line status during dialing is shown below.
CML Relay
Dial Pulse
Generate Circuit
Line status
DTMF Tone Generator
The DTMF Tone Generator is incorporated in the MODEM on the SC 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. Digital amplitude signal is conveyed as analog amplitude signal through D/A
converter in the DAA (IC23). The line status during dialing is shown below.
CML Relay
Line status
Ring Detector
When the unit is in the Sleep Mode status, a Ringing signal is detected by a photo-coupler (PC2) in Ring
Detector to cancel the power-save for waking up. Then DAA (IC23) detects the ringing signal for receive
mode.
When the unit is normal operating status, DAA (IC23) detects the ringing signal immediately.
break
make
break
make
Speech
Line release condition
break Prepause
make
break
make
Speech
Line release condition
break
make
First Speech
digit condition
Inter-digit
pause
First Speech
digit condition
Inter-digit
Signal time
pause
DTMF signal
208
Second Speech
digit condition
Second Speech
digit condition