| 摘要 |
PURPOSE:To keep the loop gain constant and reduce the level contrast, by negating a part where the service level has exceeded a set point, and removing a loss of a variable gain (loss) means of the transmission and receiving channel by the same amount as said negated loss. CONSTITUTION:The variable loss means A3S', A3R' which can remove a loss of 0-alphadB continuously or at step intervals are provided. And now, when there is a transmission signal from the S side, a loss of the variable loss means A1S, A2S, A3S', A4S', A1R, A2R, A3R', A4R is 0, 0, 0, 0, 0, alpha, alpha, 0dB, but when a voice service mean level at the 4-wire output point (p) exceeds a level which has been set in advance, by betadB, the control information S1 for negating the excess level is sent out from the voice mean level detection circuit DETS. A loss of the variable loss means A1S and A4R is set to betadB by said information S1. Also, the information S1 is sent out to the voice comparator circuit. |
