Description Of Block Diagram In Analog Section - Panasonic KX-FP121AL Service Manual

KX-FP121AL / KX-FM131AL
6.7.

DESCRIPTION OF BLOCK DIAGRAM IN ANALOG SECTION

1. Function
The analog section works as an interface between the telephone line.
The analog gate array (IC551) on the digital board exchanges FAX TX and RX signals between the MODEM (IC505) and the
analog section.
The control signals transmitted to the analog section are output mainly from ASIC IC501, and the analog status is stored as data
in ASIC IC501.
2. 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; Pulse dial generation circuit; Extension phone line off-hook detection circuit;
Sidetone circuit; Remote fax activation circuit.
Refer to 6.8. NCU SECTION for the details.
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