Description Of Block Diagram In Analog Section - Panasonic KX-FP81BX Service Manual

KX-FP81BX / KX-FP81CX / KX-FP82CX
6.7.

DESCRIPTION OF BLOCK DIAGRAM IN ANALOG SECTION

1. Function
The analog section serves as an interface between the telephone line. The digital board (IC505) for transmission and reception
of FAX signals, switches between the digital board (IC505) and other sections by means of a multiplexer in the NCU section.
The control signals to the individual analog sections are output mainly from ASIC IC501, and the status information for the
various sections is also held in ASIC IC501.
Simple explanations for the various sections are given below.
2. Circuit Operation
[NCU Section]
This is the interface between the telephone line and external telephone. This is composed of a bell detection circuit, pulse
dial generation circuit, EXT. TAM OFF-HOOK detect circuit, vox circuit, amplifier circuit for line transmission and reception,
sidetone circuit, etc.
[Modem (IC505)]
This is used for FAX signal tone modulation, DTMF signal transmission, ring tone generation, and line transmission beep
generation. The DTMF signal and beep are placed into the TX system. The ring tone passes through the analog switch and
is output to the speaker via the power amplifier (IC102).
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