| 摘要 |
PCT No. PCT/JP94/00653 Sec. 371 Date Nov. 17, 1994 Sec. 102(e) Date Nov. 17, 1994 PCT Filed Apr. 20, 1994 PCT Pub. No. WO94/24779 PCT Pub. Date Oct. 27, 1994At the time of receiving a repeater supervisory signal superimposed on or combined by wavelength multiplexing with a main optical signal in an optical amplifier repeater system, the received optical signal is subjected to a photoelectric conversion by a photodetector and then branched into two electric signals, the one of which is subjected to equalizing amplification, timing extraction and discrimination and regeneration to extract only the main signal component. The main signal component thus extracted and the main signal contained in the other electric signal, which is not regenerated, are respectively subjected to required equalization, delay adjustment and amplitude adjustment so that they match with one another in waveform, phase and amplitude. In addition, the amplitude adjustment of the main signal is automatically controlled. By differentially combining these signals to remove only the main signal component to minimize its residual value, thereby extracting the supervisory signal to be obtained.
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