| 摘要 |
The present invention relates to a digital signal multiplex and communication system having monitoring function of the signal path. The digital path monitoring method according to the present invention comprises step of counting "1"s included in information bits sandwiched by two stuff pulses for each lower-rate signal before multiplexing a plurality of lower-rate signals into one higher-rate signal, step of inserting a parity bit corresponding to the number of "1"s obtained as a result of the connecting step into the latter stuff pulse insertion position of the lower-rate signal which appears just after the counting, step of multiplexing the lower-rate signals with the parity bits inserted, step of transmitting the higher-rate signal obtained as a result of the multiplexing step, step of demultiplexing the higher-rate signal into a plurality of lower-rate signals, step of counting, for each of the lower-rate signals obtained as a result of the demultiplexing step, "1"s included in a information bits sandwiched by two parity bits which are adjacent, step of checking the number of "1"s thus connected with the parity bit which appears just after the counting, and step of judging if the digital path is normal of abnormal on the basis of the result of the checking step.
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