Panasonic KX-FLB758RU Service Manual page 168

KX-FLB758RU
7.3.3. MODEM CIRCUIT OPERATION
The CODEC (IC609) and ASIC (IC604) has all the hardware satisfying the CCITT standards mentioned previously.
ASIC (IC604) controlled codec (IC609) by senial data.
This CODEC (IC609) and ASIC (IC604) has an automatic application equalizer. With training signal 1 or 2 at the time of G3
reception, it can automatically establish the optimum equalizer.
1. Facsimile Transmission/DTMF Line Send
The digital image data on the data bus is modulated in ASIC(IC604), and sent from pin 9 and 10 via CODEC(IC609),amplifier
IC204(5/6→7). Analog gate array IC201(24→22), electric volume IC202(14→15),amplifier IC207(2→1) and the NCU section to
the telephone line.
Refer to CHECK SHEET(P.137).
2. Facsimile Reception
The analog image data which is received from the telephone line passes through the NCU section and enters pin 13 of the
CODEC (IC609). The signals that enter pin 13 of the CODEC (IC609) are demodulated in the board to digital image signals and
then send pin p1 of the ASIC (IC604).
In this case, the image signals from the telephone line are transmitted serially. In the ASIC (IC604). Here, the internal equalizer
circuit reduces the image signals to a long-distance receiving level.
This is designed to correct the characteristics of the frequency band centered around 3 kHz and maintain a constant receiving
sensitivity.
It can be set in the service mode.
Refer to CHECK SHEET(P.137).
3. DTMF Transmission (Monitor tone)
The DTMF signal generated in the ASIC (IC604) is output from pin P3, and the NCU section to the telephone line the same as
facsimile transmission signals.
(DTMF Monitor Tone)
Refer to CHECK SHEET(P.137).
4. Call Tone Transmission
This is the call signal which is generated the ASIC (IC604) and sent to the speaker.
Refer to CHECK SHEET(P.137).
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