| 摘要 |
A step-by-step remote locating system for a digital bidirectional transmission link includes repeater pairs between a monitoring end equipment and a remote equipment. The monitoring equipment transmits remote location sequences and a locate end interruption on a forward channel. The sequences are intended to command closing and opening respective loop-back paths between two repeaters of the pairs. Each sequence comprises a predetermined integral number k of nonconsecutive interruptions in a transmitted digital signal throughout a predetermined period and, with the exception of the first sequence, an interruption preceding the k interruptions intended for opening the loop-back path of the preceding pair. The remote locate circuit associated with each repeater pair comprises an interruption counter. When the count of the counter is k the respective loop-back path to the monitoring equipment is closed. When the count is not equal to k, the loop-back path is opened. The count of the counter automatically returns to zero in response to a count less than k at the end of the predetermined period or in response to a locate end interruption longer than the predetermined period. |
