检测正弦信号在过零点处是否能与输入的波形保持一致，实现锁相功能-detection zero crossing

锁相环用于电机转速精准检测，资料很不错，值得下载-Phase-locked loop for accurate detection of motor speed

通过labview控制信号发生器和锁相放大器进行共振频率检测的程序。freq test.vi实现信号发生器的频率扫描，lockin test.vi 实现锁相放大器的参数设定，数据采集.vi实现锁相数据的采集，waveform arrays to file实现波形数据到文件数据的转换。共振频率测试.vi实现晶振等共振频率的测试-Resonance frequency detection procedures performed by labview control signal generator