Panasonic KX-MB2085CXW, Service Manual

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KX-MB2085CXW/KX-MB2090CXW
6.3.3. Modem Circuit Operation
The modem (Included IC300) has all the hardware satisfying the CCITT standards mentioned previously.
ALL processing is controlled by the SOC (IC300) according to CCITT procedures.
This modem (Included IC300) has an automatic application equalizer. With training signal 1 or 2 at the time of G3 reception, it can
automatically establish the optimum equalizer.
Facsimile Transmission/DTMF Line Send
The digital image data sent on ATXD line from modem (Included IC300).
AFE IC (IC200) and Analog DAA
*1
circuit to the telephone line.
Facsimile Reception
The analog image data which is received from the telephone line passes through Analog DAA circuit and enters AFE IC(IC200).
The signals are changed to digital data in AFE IC and IC300. In this case, the image signals from the telephone line are trans-
mitted serially. 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.
Busy/Dial Tone Detection
The path is the same as Facsimile Reception.
Call Tone Transmission
This is the call signal which is generated the SOC (IC300) and sent to the speaker.
*
1
DAA : Direct Access Arrangement
6.3.4. TEL Line Section
Composed of ITS circuit and NCU circuit.
6.3.4.1. Description of Block Diagram in Analog Section
Function
The analog section works as an interface between the telephone line.
DAA control ITS circuit and NCU circuit.
DAA control signals are output from Soc IC300.
Circuit Operation
[NCU]: Network Control Unit the NCU comprises of the following; DC loop forming circuit to connect with the telephone line;
Switching circuit for other interconnected telephones; Bell detection circuit; Remote fax activation circuit.
Refer to
NCU Section (P.29) for the details.