The output from incremental optical encoders and from many other types of measurement devices is known as a “quadrature” signal. A quadrature signal consists of two square waves 90° out of phase. The input channel on our encoder interface board count

频率的测量实际上就是在1s时间内对信号进行计数，计数值就是信号频率。用单片机设计频率计通常采用两种办法，第一种方法是使用单片机自带的计数器对输入脉冲进行计数；第二种方法是单片机外部使用计数器对脉冲信号进行计数，计数值再由单片机读取。-In the measurement of frequency is actually 1s to count time signal, numerical is signal frequency. Using single-chip microcomputer f