| 摘要 |
In receiving the repeater monitoring signal multiplexed by superposition or wavelength multiplexing of the optical signal of the main line in an optical amplification repeat system, the received optical signal is photoelectrically converted by a photodetector and the electrical signal is divided into two. One of the electric signals is subjected to equalizing amplification, timing extraction and recognition reproduction so that only the signal component of the main tack is extracted. The waveform, phase, and amplitude between this extracted signal component and the signal of main line contained in the other signal which is not subjected to recognition reproduction are made to coincide with each other by executing the required equalization, delay adjustment and amplitude adjustment. An automatic control function is provided to the circuit for adjusting the amplitude of the signal of the main line so as to differentially combining the two signals. Thus, the main line signal component is so removed that the level of the remaining component is a minimum, and the desired repeater monitoring signal is extracted. <IMAGE> |
