General Description:17 CIRCUIT OPERATION (Base Unit)(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 thatfunctions as follows.17.1. DSP (Digital Speech/Signal Processing: IC501)17.1.1. Function· Voice Message Recording/Play backThe 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/GeneratorThe 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 thevocabulary.· Caller ID and Call Waiting CID demodulationThe DSP implements monitor and demodulate the FSK signals that provide CID information from the Central Office.· Analog SwitchingThe voice signal from Handset is transmitted to the speaker or the voice signal from Digital TAM System is transmitted to theTelephone line, etc. They are determined by the signal path route operation of voice signal.· Block Interface CircuitRF unit, LED, Key scan, Speaker, Microphone, Telephone line, LCD.76KX-TG2359BXB
