| 摘要 |
PURPOSE:To confirm a system margin of an optical relay system accurately by providing a monitor circuit so as to control an automatic gain control circuit being a component of an equalizing amplifier circuit thereby varying an output amplification of the equalizing amplifier circuit and varying the S/N of the received waveform equivalently. CONSTITUTION:A control signal 11 is inputted between a band pass filter 9 end an automatic gain control circuit 7 to give a prescribed change and the result is outputted as a control signal 11a to control the automatic gain control circuit 7 and a monitor circuit 8 varying the output amplification of the equalizing amplifier circuit 2 is provided. A transmission signal 10 after identification reproduction is given to the band pass filter 9 to demodulate the control signal 11 and to activate the monitor circuit 8, the control signal 11a controls the automatic gain control circuit 7 thereby varying the output of a broad band amplifier circuit 6, that is, the output amplitude of the equalizing amplifier circuit 2. Thus, the S/N of the signal inputted to an identification circuit 4 is changed equivalently to vary the code error. The system margin is confirmed accurately by observing the deterioration in the code error. |
