声速测量实验方法的改进

IMPROVEMENT OF SOUND VELOCITY MEASUREMENT METHOD

基于虚拟仪器的设计原理,针对振幅法测量声速实验中存在的问题进行了改进,设计了一个基于单片机的声速测量实验系统.该系统中,单片机对接收端信号进行采样并控制端面匀速移动.采集到的数据序列传输到PC机进行中值滤波,由快速傅里叶变换对序列进行预处理,再进行较精确的极值点检测,并通过线性回归方法对结果进行校正.该改进装置提高了实验的准确性和自动化程度,作为原实验方法的有益补充,可应用于大学基础物理实验及课堂演示教学环节,也可应用于声波近场区传播规律的研究.

According to the design principle of virtual instruments,a sound velocity measurement system based on microcontroller unit is realized,which compensates for some problems of the original experiment with amplitude approach.In this system,the microcontroller unit samples the received signals and controls the uniform motion of the receiver.The data array is uploaded to the personal computer（PC）,which is firstly processed with median filtering,followed by the fast Fourier transform.Then the more precise detection of extreme points and linear regression for further correction are implemented.In contrast to the manual operation,the system improves the accuracy of the measurement with good effects of human-computer interaction,which complements the original experiment and teaching demonstration,and also can be applied to research on the laws of the acoustic near-zone spread.