| 摘要 |
PURPOSE:To establish a testing method in a time-division direction-control transmission system of a one-element type by a method wherein an optical fiber provided with a reflecting point in one end is connected to a semiconductor laser in the end opposite to that end. CONSTITUTION:At the time of an ordinary operation, a signal from an information supply source such as a terminal device is supplied to a drive circuit 15 and a semiconductor laser 11 is driven by a signal of the circuit. At the time of a test, an optical fiber 12 is connected to the laser 11 in place of an optical fiber transmission path and a test signal from a test signal generating circuit 14 is supplied to the circuit 15. Based on this test signal, the circuit 15 drives the laser 11 and a testing light signal is generated therefrom. This light signal is propagated through the optical fiber 12, reflected by a reflecting part 13 and propagated again through the optical fiber 12 in the reverse direction and enters the laser 11. The laser 11 being set in a reception mode at this time, the signal is detected by a reception circuit 16. In this way, it can be checked up whether an operation is normal or not. |
