| 摘要 |
PURPOSE:To ensure good communication through a digital telephone set, by sending the voice from a transmitter microphone to a receiver and having detailed control of the voice sending value. CONSTITUTION:The aural signal given from a transmitter microphone is supplied to an A/D conversion input terminal of a CODEC62 to be converted into a nonlinear digital signal and fed to a nonlinear circuit 73 of a digital circuit 63 as well as to a buffer circuit 77. The digital signal converted into a nonlinear form by the circuit 73 is attenuated 72. At the same time, the nonlinear signal fed to the circuit 77 is converted into a transmission format signal by a separating/synthesizing circuit to be transferred to an exchange. While the audio signal given from the exchange is separated 78 from a control signal and converted into a linear signal through a buffer circuit 76. This linear signal is added 71 with the signal which is attenuated 72 and then converted into a nonlinear digital signal. This nonlinear digital signal is supplied to the CODEC62 and converted into an analog signal to be sent to a telephone receiver. |
