| 摘要 |
PURPOSE:To attain sure measurement of the error rate of a repeater, by controlling a clamp circuit with an output of a switching circuit for controlling the switching of a main signal folding path through the control. CONSTITUTION:A transistor(TR) 18 and resistors R1, R2 constitute the clamp circuit 15, and a comparison circuit 17 and a TR19 constitute the switching circuit 14. The setting of a clamp level of the circuit 15 is performed by adjusting the values of voltage dividing resistors R1, R2. On the other hand, a circuit 13 extracting the frequency of a monitoring circuit receives a monitoring signal outputted from an NRZ/NZ converting section 6 via a point (a) and extracts a monitoring signal. Further, when the received monitoring signal includes the corresponding frequency component, the circuit 13 outputs a signal bringing the output of the comparison circuit 17 to a low level, resulting the TR19 nonconductive and no effect is exerted on the clamping operation of the TR13, and the signal is transmitted directly from the point (a) to the point (b). |
