| 摘要 |
PURPOSE:To facilitate the forming of a loopback line, by connecting a 2-input 2-output switch and a circuit for the switch to two optical reproducing devices so as to connect the outputs of the two optical reproducing devices to an opposite line mutually. CONSTITUTION:The output of optical reproducing repeaters 1, 1' is outputted from a terminal (a) to (b) of the optical switch of the 2-input 2-output type and from a terminal (c) to (d) in the nonoperation of an optical switch drive circuit 4. When the circuit 4 is activated, the terminals (a, b) and (c, d) of the switch 3 are connected and the outputs of the optical reproducing repeaters 1, 1' are outputted to the opposite lines and the resulting signal is looped back. Thus, the signal loopback is ensured easily by the external control. |
