| 摘要 |
PURPOSE:To secure a natural cell level over a wide line length by inputting an output of a detection means of a call current to a cell loss compensation means and controlling a call loss compensation amount in accordance with the call current value. CONSTITUTION:A sound signal, which arrives from a terminal device 1 and appears at both ends of a resistance 38, is amplified by an amplifier 312 of a call loss compensation circuit 31. On the other hand, a DC voltage in correspondence to a subscriber line length is outputted from a current detection circuit 30, and impressed to a base input of an FET310 through a current reducing resistance R5. When a line resistance value is small, a call current becomes larger, whereby the voltage impressed to the base input of the FET310 is large. Then a conduction resistance is small, and gains of the circuit 31 become small. Meanwhile, when the line resistance is large, gains of the circuit 31 become large, thereby compensating losses of a sound signal. |
