全自动声速测量及实验数据处理研究  

AUTOMATIC MEASUREMENT OF SOUND VELOCITY AND DATA PROCESSING

作　　者：石明吉[1] 罗鹏晖[1] 陈兰莉[1] 宋金璠[1] 刘斌[1] SHI Mingji;LUO Penghui;CHEN Lanli;SONG Jinfan;LIU Bin(School of Electronic and Electrical Engineering,Nanyang Institute of Technology,Nanyang Henan 47300)

机构地区：[1]南阳理工学院电子与电气工程学院,河南南阳473004

出　　处：《物理与工程》2018年第4期125-129,共5页Physics and Engineering

基　　金：南阳理工学院省示范校建设专项研究项目(SFX201718);南阳理工学院高等教育研究基金项目(2017-NGGJJJ-002)

摘　　要：针对大学物理实验中传统声速测量装置存在的缺陷,利用单片机、上位机、步进电机、步进电机驱动器、采集卡、有效值检测模块和相位差测量模块等搭建了全自动声速测量系统,利用驻波法和相位比较法对声速进行测量。实验结果表明:新型声速测量仪克服了传统测量装置的缺陷,获得的数据量更大,包含的信息也更丰富。由于次峰的影响,常用的逐差法、最小二乘法和Origin软件线性拟合法处理数据误差较大,不能满足实验需要,有必要寻找声速测量数据处理的新方法。为排除次峰的影响,考虑到声速测量数据中极值点的出现具有空间周期性,利用傅里叶变换处理数据得到待测信号的空间频谱图,确定了声波的波长并计算出声速。数据处理结果表明:由于傅里叶变换排除了次峰干扰,使驻波法和相位比较法测量声速的相对误差分别从1.6%和1.0%减小为0.71%和0.41%,比传统方法更适合于处理声速测量数据;此外,从另一个角度证明次频共振现象是形成次峰的重要原因。Aiming at shortcomings of traditional sound velocity measuring instrument used in college physics experiments,a set of automatic sound velocity measurement instrument was designed and fabricated which was composed of the micro-controller,upper machine,stepping motor,motor driver,data acquisition card,effective value detection module and phase difference measurement module.This instrument makes it possible to measure sound velocity precisely by standing wave method and phase comparison method.The experimental results show that the new instrument overcomes the shortcomings of traditional measuring instrument,and obtains greater amount of data and more abundant information.Due to the influence of submaximum phenomenon,the commonly used methods,such as the successive difference method,the least square method and the linear fitting method by Origin software,cannot meet the needs of data processing for large errors.It is necessary to find a new method for data processing of sound velocity measurement.In order to eliminate the influence of sub-maximum phenomenon,considering the occurrence of extreme points in the sound speed measurement data has spatial periodicity,we use Fourier transform to process the data to get the spatial spectrum of the signal,determine the wavelength of the acoustic wave and calculate the sound speed.The data processing results show that Fourier transform eliminates the interference and reduces the relative error from 1.6%and 1.0%to 0.71%and 0.41%,which is more suitable for processing the measurement data of sound velocity.From another point of view,the sub-frequency resonance phenomenon is an important reason for the formation of sub-maximum phenomenon.

关 键 词：声速测量仪 逐差法 最小二乘法 傅里叶变换 次峰 次频 空间周期性 

分 类 号：O422.1[理学—声学]