Panasonic KX-TGA740, Service Manual

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KX-TG7411MEB/KX-TG7412MEB/KX-TGA740MEB
4.4. Circuit Operation (Base Unit)
General Description:
(DSP, EEPROM) 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.
4.4.1. DSP (Digital Speech/Signal Processing: IC501)
• DTMF Generator
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/DTMF signals that provide CID information from the Central Office.
• Digital Switching
The voice signal from telephone line is transmitted to the handset or the voice signal from the handset is transmitted to the Tele-
phone line, etc. They are determined by the signal path route operation of voice signal.
• Block Interface Circuit
RF part, LED, Key scan, Telephone line.
4.4.2. EEPROM (IC611)
Following information data is stored.
• Settings
ex: ID code, Flash Time, Tone/Pulse