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15 CIRCUIT OPERATION (Base Unit)
General Description:
(DSP, Flash Memory) is a digital speakerphone/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
functions as follows.
15.1. DSP (Digital Speech/Signal Processing: IC201)
• • Voice Message Recording/Play back
The DSP system use 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 Detection/Generator
The DTMF detection is implemented by the DSP system in software. The DTMF detection is performed during Record,
Playback, and Line Monitoring modes of operation.
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 an FLASH MEMORY, which stored the
vocabulary.
• • Caller ID and Call Waiting CID 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 unit, LED, Key scan, Speaker, Microphone, Telephone line, LCD
15.2. Flash Memory (IC300)
Following information data is stored.
• • Voice signal
ex: Pre-recorded Greeting message, Incoming message
• • Telephone number, etc.
ex: Telephone Directory number, Caller ID data, ID code
• • Settings
ex: message numbers, caller ID numbers, pulse tone dial
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KX-TG2257BXS
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