| 摘要 |
<p>PURPOSE:To easily detect the occurrence of failure station, by providing the oscillation boards having specific and a given frequency in each non-attendant relay station and by using them with changeover. CONSTITUTION:The failure retrieval current oscillating boards 4, 4' of a specific frequency and the failure detecting oscillator 6 of a given frequency in common use for each relay station are placed in each non-attendant relay stations 2, 2'. Normally, the current from the oscillation boards 4, 4', is all fed to the communnication delivery line 1, and on failure, the station in failure selects the current supply to the delivery line from the oscillation board 4 to 6 with the operation of relay. The occurrence of failure is informed with the detection of the current of a given frequency by the terminal station 7 and the failure station can be detected with the detection of the disappearance of the current of a given specific frequency.</p> |
