| 摘要 |
PURPOSE:To realize the stable and accurate circuit monitor with compensation of the influence of the noise level fluctuation by changing the gain of the 2nd DC amplifier of a noise deciding circuit or the noise deciding level based on the output of a pilot signal deciding circuit. CONSTITUTION:The gain of a gain variable DC amplifier 9 or the deciding level of a 2nd deciding circuit 10 is changed by the output of a 1st deciding circuit 5 so that these gain and level can follow even in case of the level fluctuation of a pilot signal or the interruption of this signal. Thus the influence of the noise level fluctuation can be compensated. In other words, the pilot signal level and the noise level are decided by the circuits 5 and 10 respectively. Then the gain of the amplifier 9 is controlled by the output of the circuit 5 so that the fluctuation characteristics of the noise detecting level caused by the pilot signal level can be compensated. As a result, an effective noise level can be detected even when the pilot signal level has fluctuation or is interrupted. |
