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KX-TG9333PK/KX-TG9334PK//KX-TGA931T
4.4. Circuit Operation (Base Unit)
General Description:
(DSP, Flash Memory) is a digital speech/signal processing system that implements all the functions of speech compression,
record and playback, and memory management required in a digital telephone answering machine.
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)
• Voice Message Recording/Play back
The DSP system uses a proprietary speech compression technique to record and store voice message in Flash Memory.
An error correction algorithm is used to enable playback of these messages from the Flash Memory.
• DTMF Generator
When the DTMF data from the handset is received, the DTMF signal is output.
• Synthesized Voice (Pre-recorded message)
The DSP implements synthesized Voice, utilizing the built in speech detector and a Flash Memory, which stored the vocabulary.
• 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, Speaker, Microphone, Telephone line.
4.4.2. Flash Memory (IC601)
Following information data is stored.
• Voice signal
ex: Pre-recorded Greeting message, Incoming message
• Settings
ex: message numbers, ID code, Flash Time, Tone/Pulse
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