| 摘要 |
PURPOSE:To automatically and promptly discover the fault part of a communication line by providing a line monitor circuit and a memory in a modulator- demodulator. CONSTITUTION:In a modulator-demodulator 1, a line monitor circuit 2 and a memory 3 are possessed, and exchange data are all recorded in the memory 3 in a digital data form by the line monitor circuit. Further, the line monitor circuit 2 has a function to output the other special bit column to digital data 5 for the special bit column of digital data 7, thereafter, to compare the data inputted from the digital data 5 with the date read from the memory 3, and returns bit error information as a result to the digital data 7. When plural modulator-demodulators are serially connected, by executing a comparing operation of the modulator-demodulators in the sequence of the one connected in a vicinity, which part of the communication line includes the fault part can be judged. |
