| 摘要 |
PURPOSE:To ensure a detection for the variation of the input frequency with every 1/4 cycle, by delivering the pulse signal after detecting both the maximum and minimum values of the absolute value signal of the analog signal input. CONSTITUTION:The sine wave input signal ea is converted into the absolute value signal ¦ea¦ and then supplied to the comparators 21 and 31 of the positive and negative peak detecting circuits 2 and 3 each. When the input signal ea reaches the maximum values of 1/2pi and 3/2pi each, the output ed of the comparator 21 is reduced down to the level of -1 and inverted by the inverse amplifier 22 to be put into the one-shot circuit 5 via the clipper circuit 4. Thus the pulse Pa of a certain width is delivered. When the signal ea reaches the minimum values of pi and 2pi each, the output of the comparator 31 rises up to the level of +1 and is then put into the one-shot circuit 8 via the clipper circuit 7 to deliver the pulse Pb. These pulses Pa and Pb are then delivered sequentially through the OR circuit OR and in the form of the pulse P. |
