频率计，基本设计原理是直接用十进制数字显示被测信号频率的一种测量装置。它以测量周期的方法对正弦波、方波、三角波的频率进行自动的测量。-Frequency meter, the basic design principle is directly with decimal digital display measured signal frequency of a measuring device.It with the method of measuring cycle of sine wave