摘要 |
PURPOSE:To detect out of synchronism with high accuracy by converting digitally, amount of shift of synchronism between an input signal and an output signal into a pulse train, comparing the pulse train with a set value of a counter and outputting an out of synchronism display signal. CONSTITUTION:Suppose that an oscillating frequency of an oscillator 14 is sufficiently higher than the frequency of an input signal A. If the input signal A and the output signal B are shifted mutually, a pulse train having a width equal to the amount of shift of synchronism appears at an output C of an EXOR5. A counter 11 counts pulses of an output E of an AND gate 13 for the period of out of synchronism and if the count value exceeds the set value of the counter 11 set in advance, an H level is set to a set input S of an FF12, the FF12 is inverted and outputs an out of synchronism signal S0. Thus, the out of synchronism is detected with high accuracy. |