| 摘要 |
PURPOSE:To provide possibility of independent setting of the test conditions for down-signal and up-signal by segregating them physically by the use of a nonreciprocal element. CONSTITUTION:A down-signal 5 given by a pattern generator 1 is passed through a down-signal transmission circuit 3 to be converted into optical signal, sent onto a transmission path, fed to the first photo-circulator 7 from its port 1 to be emitted out of another port 2 thereof, passed through a photo-attenuator 8, fed to the second photo-circulator 7' from its port 3 to be emitted out of another port 1 thereof, being converted into electrical signal, and fed to an error sensor 2' upon being passed through a down-signal reception circuit 4'. An up-signal 6, on the other hand, is given by a pattern generator 1', passed through an up-signal transmission circuit 3' to be converted into optical signal, sent onto a transmission path, fed to the second circulator 7' from its port 2 to be emitted out of another port 3 thereof, passed through a photo-attenuator 8', fed to the first circulator 7 from its port 3 to be emitted out of its port 1, being converted into electric signal, and fed to another error sensor 2 upon being passed through an up-signal reception circuit 4. |
