| 摘要 |
PURPOSE:To lower the frequency of a basic clock CLK and to make a measurement time constant by providing the 1st and the 2nd counters which count clock pulses and pulses from a sensor, etc., and measuring the frequency of pulses on the basis of the counted values N and M of both counters. CONSTITUTION:When a D flip-flop 4 is set, the counters 1 and 2 begin to count CLK and MPU respectively. The frequency (f) of MPU is found from f=1/n.DELTAT/M based upon the rest counted values N and M of the counters 1 and 2. In this case, DELTAT is the period of clock pulses. Thus, not the time of one period of pulses, but period intervals which are several - hundreds of times as large as one period are measured to measure the frequency of the pulses, and consequently the frequency of a basic clock for the measurement is lowered and the measurement is completed within a nearly constant measurement time. |
