| 摘要 |
PURPOSE:To enable highly accurate judgement of high or low level of frequency in a wide range, by using two one-shot pulse generation circuits and a D flip flop circuit to perform a signal processing of a digital signal as intact. CONSTITUTION:When a signal with the cycle shorter than an output pulse width T1 of a one-short pulse generation circuit 2, namely, a high level of frequency is inputted into an input terminal 1, an output of a one-shot 2 goes to H and a Q output of a flip flop 6 goes to H, which turns a switch 3 to the position 3b. As a result, an output of an OR circuit 5 also is normally turned to H and an inversion Q output as judging output of the flip flop moves to an L level. Hence, a judgement is given that the input frequency is larger than 1/T1. Then, when a frequency lower than 1/(T1+T2) (wherein T2 represents an output pulse width of a one-shot pulse generation circuit 4) is inputted into the input terminal 1, a switch 3' is turned to the position 3a by a Q output of the D flip flop 6 and the judging output of the D flip flop 6 goes to an H level at the inversion Q terminal. Thus, a judgement is given that the input frequency is lower than 1/(T1+T2).
|
