| 摘要 |
PROBLEM TO BE SOLVED: To easily detect a data line fault caused by carrier-off. SOLUTION: When carrier-on is received from a counter station (step(S) 1), data received from the counter station are temporarily saved on the local memory of DCE (S3). When carrier-off is received from the counter station (S4), it is judged whether the end of data finally saved on the local memory is an ending code or not (S5) and when it is the ending code (S5: YES), it is discriminated that data receiving is normally completed. Then, processing is returned to the processing start (S1). When the end of data is not the ending code (S5: NO), it is discriminated that carrier-off has been caused by line abnormality during data receiving and a carrier-off counting advances by one (S6). Thus, detection of a line fault spot and analysis of a line quality can be facilitated.
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