Panasonic KX-TG2873BXS, Service Manual

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KX-TG2873BXS/KX-TGA280BXS
4.3.
Circuit Operation (Base Unit_Main)
General Description:
DSP is a digital speech/signal processing system that implements all the functions of speech compression and memory
management required in a digital telephone.
The DSP system is fully controlled by a host processor DSP. The host processor provides activation and control of all that func-
tions as follows.
4.3.1.
DSP (Digital Speech/Signal Processing: IC4)
DTMF Detection/Generator
The DTMF detection is implemented by the DSP system in software. The DTMF detection is performed during Record, Play
back, and Line Monitoring modes of operation.
When the DTMF data from the Handset is received, the DTMF signal is output.
Caller ID demodulation
The DSP implements monitor and demodulate the FSK signals that provide CID information from the Central Office.
Analog Switching
The voice signal from telephone line is transmitted to the speaker or the voice signal from speakerphone microphone is transmitted
to the Telephone line, etc. They are determined by the signal path route operation of voice signal.
Block Interface Circuit
RF part, LED, Key scan, Telephone line.
4.3.2.
FROM: IC501
FLASH-ROM stores base PROGRAM and following information data is stored.
Settings
ex: ID code, Flash Time, Tone/Pulse, TAM Message