输入两路方波信号，测量信号的频率和两信号的相位差，能显示频率值和相位差，精度：0.1Hz，0.10。在满足精度的前提下分析和证实系统的测量范围。-Two square wave input signal, measurement signal frequency and phase difference of two signals showing the frequency value and phase accuracy: 0.1Hz, 0.10. In the premise of mee