| 摘要 |
PROBLEM TO BE SOLVED: To easily measure with high accuracy a difference frequency with a simple circuit by comparing and outputting each counter value at the time of a stop action of a counter based on a specific procedure. SOLUTION: For example, an oscillation frequency f on a specification of generators 1, 2 is defined as 10 MHz, a nominal accuracy S is defined as 1×10<-7> and each actual frequency at this time is defined as f1 =10<7> Hz, f2 =9999999.6 Hz. An interval of a start signal and a stop signal is prepared by frequency- dividing the generator by 1×10<8> by a frequency divider circuit 5 and the interval of both start and stop signals is defined as T=1×10<8> /f1 and T=10 second. So, a counter A3 counts f1×T=10<8> times. Similarly, a counter B4 counts f2×T=99999996 times. The counter A3, B4 are sufficient cyclic counters of approximately 8 bit and the difference C is outputted as +4 by a comparator 6. The fact indicates that the frequency of f1 is higher by 0.4 Hz than that of f2 .
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