| 摘要 |
<p>PURPOSE:To execute easily and exactly a search of a repeater fault, by constituting so that a monitoring station converts a difference-converted signal to a code by a CMI code rule and sends it out, and each repeater station sum-converts a receiving signal, and transfers the signal converted to the monitoring station when a low frequency component of the signal coincides with specified frequency. CONSTITUTION:A repeater station 2 discriminates and reproduces a receiving signal by a repeater 31, sends it out to the following repeater station, and also sum-converts the receiving signal by a frequency dividing circuit by a flip-flop, namely, a sum-converting circuit 32. As for an output signal of the sum-converting circuit 32, a low frequency component is fetched by a low frequency filter 33. This low frequency component corresponds to a periodical variation of generation probability of ''1'' of an output signal 23 of said exclusive OR circuit 13. When frequency of the low frequency component concerned coincides with specified frequency assigned to itself, the signal is sent out to a low frequency transmission line which is not shown in the figure, through a band-pass filter 34. By receiving this signal and monitoring its phase variation by a monitoring station 1, a transmission error can be detected.</p> |
