基于锁定放大器的声速测量法

Measurement of speed of sound using lock-in amplifier

介绍一种用锁定放大器替代示波器确定声波相位,进行声速测量的方法.利用锁定放大器的高灵敏度、高信噪比的特点,能有效地提高实验装置的抗干扰性和测量准确度,被测量对象也可由原单一频率的超声波改变为任意频率的声波.本实验不确定度<5%,若采用更精密的仪器,实验不确定度很容易达到0 5%.

A new method measuring speed of sound is proposed instead of oscilloscope.The lock-in amplifier is used in the measuring systems; the measure precision and anti-interfere are improved. The object to be measured is extended from ultrasound of definite frequency to the sound wave of arbitrary frequency. The measurement has an accuracy of 5 percent.