Keyphone system's analog main wire and extension interface board and transmission characteristics control method and Keyphone system

摘要

PURPOSE: Analog office line and extension interface boards for a keyphone system and a method for controlling a transmission characteristic are provided to receive a necessary DSP(Digital Signal Processor) coefficient value according to a country selected by a user and be operated. CONSTITUTION: Analog office line and extension interface circuits(110,210) have DSP coefficient value dedicated memories(130,230) for receiving and storing a DSP coefficient value which satisfies the transmission characteristic specification of an office line and an extension connected to a keyphone system. The analog office line and extension interface circuits(110,210) have DSP codec filters(120,220) for impedance matching and the PCM(Pulse Code Modulation) conversion of a voice signal.