| 摘要 |
PURPOSE:To improve speech quality by inserting and removing the loss of a transmission and a reception path complementarily on the result of a comparison between a transmitted voice level and a received voice level, by performing the comparison for a certain time after the transmitted voice signal level increases above a stationary noise level. CONSTITUTION:In response to a transmission input (a), the 1st and 2nd rectifying charging and discharging circuits 1 and 2 are charged and discharged in different states, and their outputs are compared by a comparing circuit 3; when its potential exceeds a preset potential, a switch circuit 5 receiving the output of the circuit is controlled by a control circuit 4. In response to a reception input (b), a rectifying charging and discharging circuit 7 is charged and discharged and its potential is inputted to and compared by a comparing circuit 8 with the potential of a transmission side from the circuit 5 to charge and discharge a charging and discharging circuit 9 on the basis of the comparison result, applying its output to a loss control circuit 10. According to the output of the circuit 10, variable attenuating circuits 12 and 13 which insert and remove the losses of the transmission and reception inputs (a) and (b) are controlled to perform the insertion and removal of the losses complementarily, improving speech quality. |
