| 摘要 |
PURPOSE:To immediately return to a stable batch polarized wave control state by switching immediately to a receiver for receiving a signal light of a different frequency, in the case a fault, etc., are generated in a receiver which is being monitored, and executing a polarized wave control so that its receiving signal intensity becomes maximum. CONSTITUTION:A switching circuit 21, in the beginning, outputs receiving signal intensity 18 of a second signal light 6 as a monitor signal 22. In the case this receiving signal intensity 18 attenuates or disappears by some cause, the switching circuit 21 switches it immediately to receiving signal intensity of other signal light. Also, switching is stopped by a channel which can be brought to polarized wave control stably. |
