| 摘要 |
PURPOSE:To measure the characteristics of the optical cable after laying simply, conveniently, and precisely, by alternately switching several base band frequencies to be measured automatically, sending out said frequency, and converting the received output signal into one intermediate frequency. CONSTITUTION:The outputs from oscillators 10-12 are switched by a switch 13 at a period (a), converted 14 into optical signals, and sent to the optical cable 2 to be measured. In the device 3 on the receiving side, the amplified outputs f0-f2 are converted into one intermediate frequency by a mixer 36 and local oscillators 33 and 34. In this case, the frequency of the oscillator 33 is given to the mixer 36 through a switch 35, and the amplitude A0 of the output IF at this time is memorized in a computing device 38. Then the output of the oscillator 34 is given to the mixer 36, and the IF output similar to the case of f0 is obtained with respect to input frequencies f1 and f2. The signals having the amplitudes A1 and A2 are memorized in the computing device 38 through a detector 37. By computing these signal in the computing device 38, the base band loss and the frequency characteristics in the cable 2 are obtained. |
