| 摘要 |
PURPOSE:To apply an FET to an automatic gain controller by giving a butterfly operation to the sampling value given from an input part to count the overflow value produced from said operation and decreasing and increasing the gain of the input part when the overflow value is lower and higher than a prescribed level respectively. CONSTITUTION:The input signal given from a transducer 12 is sampled by a sample and hold circuit 14 with the timing pulse sent from a timer 6. This sampling output is supplied to a gain controller 22. The output of the controller 22 undergoes the prescribed sequence processing through an A/D sample and hold circuit 24, an A/D converter 26, a time window 32, etc. and is supplied to a butterfly operation device 36. The results of operations of the device 36 are counted by a counter 50, and the overflow values of these operation results are latched by latches 52, 54 and 56. Then the gain of the controller 22 is decreased and increased by a processor 60 when said overflow value is lower and higher than a prescribed level respectively. Thus an FET is applied to the controller 22.
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