| 摘要 |
PURPOSE:To transmit normally a sub-signal with a simple circuit even if an optional existing sub-signal transmission system is failed by using a hybrid line of plural existing transmission systems and transmittting and receiving the same sub-signal while being superimposed on the line at the same time. CONSTITUTION:Repeaters 3, 4, 6 and 7 of a terminal station are in operation respectively, repeaters 5, 8 of a terminal station are spare devices, transmission lines 9, 10 are in operation and a transmission line 11 is a spare line in the terminal station 1 at the transmission side and the terminal station 2 of the reception side. Further signal lines 12, 14, 16 18, 20 and 22 are sub-signal lines and lines 13, 15, 17, 19, 21, 23 are main signal lines. If the existing transmission system using the repeaters 3, 6 is failed, the main signals 13, 19 are switched to the spare lines 17, 23 but the sub-signal cannot be switched. Even if the repeaters 3, 6 are failed, however, the sub-signal is transmitted and received normally by the system of the repeaters 4, 7 via hybrids HYB 24, 25 by using the hybrids HYB 24, 25 to transmit and receive the same sub-signal. |
