| 摘要 |
PURPOSE: A voice access apparatus in an exchange is provided to transmit the voice of a telephone to an ATM exchange using a CVSD(Continuously Variable Slope Deltamodulation) encoder/decoder and to transfer a voice signal, transmitted through the ATM exchange, to the telephone after amplifying it. CONSTITUTION: A voice access system is composed of a telephone(9) and an ATM exchange(8). A line interface part(7) is inserted between the telephone(9) and the ATM exchange(8). The telephone(9) is comprised of a mike transformer(1), a transmitting amplifier(2), a CVSD encoder/decoder(3), a volume controller(4), a receiving amplifier(5), and an MPU(6). The mike transformer(1) amplifies a slight voice signal transferred through a microphone. The transmitting amplifier(2) amplifies and transmits the signal of the mike transformer(1). The CVSD encoder/decoder(3) encodes the analog voice signal inputted through the transmitting amplifier(2) into a digital signal and transmits it to the ATM exchange(8) when a voice call is selected. Also the CVSD encoder/decoder(3) converts a terminal voice signal received through the line interface part(7) into an analog signal. The volume controller(4) adjusts the volume of a signal inputted from the CVSD encoder/decoder(3). The receiving amplifier(5) amplifies the output of the volume controller(4). The MPU(6) executes data write necessary for the volume controller(4), and transfers volume adjustment data through a data bus during a voice call.
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