| 摘要 |
PURPOSE:To form a transmission system which is very strong against an electric noise as a whole, by leading an optical fiber into the transmission system. CONSTITUTION:A light pulse which has been sent out from the light transmitter T of the central equipment M reaches the switch SW1 through the optical fiber 5, the light branching circuit 2 and the optical fiber 6. When the switch SW1 is changed to ON from OFF and therefore reflection of the switch SW1 is varied from almost zero to almost 100%, the reflected rays which have been newly generated by ON of the switch SW1 reach the light receiver R through the optical fiber 6, the light branching circuit 2, the optical fiber 5 and the light branching circuit 1 once again. The light receiver R calculates the length of the optical fibers 5, 6 by the incoming time difference between the light pulse which has been sent out by the light transmitter and this receiving pulse, and decides that this reflected pulse is a signal from the switch SW1. In the same way, ON and OFF signals from each switch can be collected by confirming whether reflected pulses from the switches SW2, SW3 exist or not. |
