| 摘要 |
PURPOSE:To discriminate frequencies with no malfunction to the single-shot noises by transmitting and holding successively the frequency discriminated output through FFs of plural stages and calculating and delivering logically both the discrimination output and the final output to processing logically the FF group. CONSTITUTION:If a single-shot noise 20 is contained in a comparison signal 1, only a discrimination noise 9 is inverted to ''L''. At the same time, the output 18 of an Ex-OR circuit 11 is changed to ''H'' since two inputs of the circuit 11 are different from each other. Then an AND circuit 17 is opened. Then a normal signal 1 containing no noise is supplied and the output 9 keeps ''L'' by the next positive polarity pulse. Then the output 13 of an FF12 is inverted to ''L''. Furthermore, the output 15 of an FF14 is also inverted to ''L'' by the next normal positive polarity pulse. However the output 9 is changed again to ''H''. Therefore, the output 9 is equal to a detection output 19, and the output 18 of the circuit 11 is set at ''L'' with the circuit 17 closed. As a result, no trigger is supplied to an FF16 although the next positive pulse is supplied. Thus the output 19 is stably kept at ''H''.
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