| 摘要 |
PURPOSE:To retrieve a wide fault by using a CMI signal being applied with equaliza tion and amplification to an input signal, a unipolar signal obtained by converting the CMI signal applied with equalization and amplification, a code information signal obtained on the basis of the input optical signal and an ouput CMI signal to apply error measurement. CONSTITUTION:A CMI unipolar conversoin circuit 13 and error measurement circuits 14,15,16 are provided in additon to an error measurement circuit 9 applying error measurement by the signal transmission from the same circuit as a code conversion circuit 4-an optical transmission line 10 in an optical opposite station the same as a conventional station to an optical transimission line 11-a code inversion circuit 7. The conversion circuit 13 is a circuit converting a CMI signal Sb into a unipolar signal Si, and the measuring circuit 14 supervises a signal between unipolar signals Sc and Si and measures the error of a circuit obtaining the unipolar signal Sc from the CMI signal Sb. The measuring g circuit 15 error measurecs the error of a circuit supervising the code rule of the CMI signal Sb and obtaining the CMI signal Sb from an input CMI signal Sa. The error measurement circuit 16 measures the error of a circuit supervising the code rule of an output CMI signal Sh and obtaining the output CMI signal Sh from a unipolar signal Sf. |
