| 摘要 |
PURPOSE:To lead signal light in a non-reception state into a reception state independently of the state of a polarized wave by sweeping and controlling the frequency of the local transmission light of a system and scrambling the polarized wave of the signal light or the local transmission light until the intermediate frequency is set to a prescribed frequency and causing the local transmission light and the reception light to coincide with each other after the intermediate frequency is set to the prescribed value. CONSTITUTION:An optical signal 1 from the transmission side is synthesized with local transmission light 2 by a coupler 3 of the system and is made incident on a front end 4 and is equalized by an equalizer 5 and is inputted to an IF filter 6, a frequency discriminating circuit 8, and an envelope detecting circuit 11. A local signal transmission source 21 is controlled by a voltage sweep circuit 14 provided between a local transmission light source 21 and a controller 12, and a deflection controller 22 to which the output of the transmission light source 21 is inputted and from which the transmission light is outputted is controlled by a sweep signal 23 and a switching signal 24 from the controller 12. Until the IF signal is set to the prescribed value, the polarized wave of the transmission light 2 or the optical signal 1 is scrambled to control coincidence between the optical signal 1 and the transmission light 2. |
