| 摘要 |
PURPOSE:To improve the operability by devising the transmitter such that one input section is used in common even when an input signal type is changed and troublesome manual changeover is not required. CONSTITUTION:When a signal in the state of a video signal is inputted to an input terminal 1, an input signal deciding circuit 2 detects it that only a component of the video signal is in existence and sends a control signal to an automatic changeover switch 3A. The switch 3A receives the signal and switches itself to a changeover contact (a). Thus, the video signal is subject to FDM in an FDM circuit 4 together with a voice signal 5 and sent to an E/O conversion circuit 6 through a switch 3B, converted into an optical signal and sent to an optical transmission line. On the other hand, when the signal subjected to FDM is inputted to the input terminal 1, the circuit 2 decides the inputted signal to detect it that the component other than the video signal is in existence. Then a control signal to switch the switch 3A to the position of a switching contact (b) is sent to the switch 3A. The signal subjected to FDM inputted to the input terminal 1 through the switch 3A is directly sent to the E/O conversion circuit 6, in which the signal is converted into an optical signal and the result is sent to an optical transmission line. |
