本文介绍了一种同步测周期计数器的设计，并基于该计数器设计了一个高精度的数字频率计。
The design of a counter measuring synchronous period is introduced in this paper. And based on it, a high precision digital cymometer is designed.
介绍了双计数器多周期同步法频率测量原理，给出了用单片机实现的具体实现方案。
The paper introduces the principle of frequency measure based on double-counter and multi-periods pulse synchronization method, and the designing with microprocessor is offered.
假设高信号使能，计数器每个时钟周期进行计数，PWM输出的频率为时钟频率的2次幂分频。
Suppose that Enable is high, the counter counts up every clock cycle, and the frequency of the PWM output is the clock frequency divided by 2 count bits.
通过移相电路获得相差90度的另一路信号，然后用可逆计数器实现稳定准确的周期计数。
Anoiher signal with 90 degree delay is obtained by phase shift circuit. The accurate and stable circle counting is done by a reversible counter.
本仪器配有电子计数器，完成预设测试周期后自动停机。
The instrument is equipped with electronic counters, complete the preset test cycle after automatic stop.
其电子计数器可控制每次测试的测试周期，配有联锁塑料盖以保证安全性。
Fitted with electronic pre-determined counter to determine the number of cycles per test, acrylic plastic cover with interlock for safety.
其电子计数器可控制每次测试的测试周期，配有联锁塑料盖以保证安全性。
Fitted with electronic pre-determined counter to determine the number of cycles per test, acrylic plastic cover with interlock for safety.
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