| 摘要 |
PURPOSE:To detect easily a fault of an error emplifier by inserting a band stop filter blocking a supervisory signal to a delay circuit side of an error detection loop and supervising a level of the supervisory signal at the output side of a feedforward amplifier. CONSTITUTION:When the error amplifier 7 is faulty and the gain is abnormal, the supervisory signal appears at an output terminal OUT. Thus, the fault of the error amplifier 7 is detected easily by supervising the level of the supervisory signal at the output terminal OUT. Then a hybrid circuit 13 is inserted to superimpose the supervisory signal from the supervisory signal oscillator 12 onto the input signal to the input side and a band stop filter 14 to stop the supervisory signal is inserted to a delay line 3 of the error detection loop. Thus, the supervisory signal does not appear at the output terminal OUT at normal state, and when the error amplifier 7 is faulty and the gain is abnormal, since the supervisory signal appears at the output terminal OUT, the fault of the error amplifier 7 is detected easily by supervising the level of the supervisory signal at the output terminal OUT.
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