| 摘要 |
PURPOSE:To improve the data transmission efficiency by not transmitting a loop test command normally and detecting it when the loop is formed even with the command of release of test. CONSTITUTION:One bit is inserted to a location representing normally an own TDM (time division multiplex) device by a 1-bit inserting section 6. Logical ''1'' is inserted as the 1-bit when logical ''0'' is inserted to an opposite TDM device. Since a flag representing the own TDM device is outputted normally from a multiplex section 4, when the loop test is normal, the flag is detected by a 1-bit detection section 10, and if an abnormality exists on a line, this flag is not detected and the flag of the opposite TDM device is detected. Thus, the loop state is diagnosed by detecting the flag (insertion bit) in this way. |
