基于Linux的声压级测量技术研究

发布时间：2018-01-26 09:24

本文关键词： 声压级实时信号处理嵌入式Linux 时间计权声级倍频程分析　出处：《浙江大学》2014年硕士论文　论文类型：学位论文

【摘要】：声学是研究物质中机械波的产生、传播和接收及其与物质相互作用的科学。声音是由物体(固体、液体和气体)的振动产生的,当一个物体振动时,就会激励周围的弹性介质随之运动,以疏密交替形式并以一定的速度向外传播而形成疏密波,这种介质的疏密波即为声波,声波会对接触物体产生压力,人能听到声音就是由于声压对耳膜产生振动而刺激神经,声级计就是将声压信号转换成电信号然后计算出声级的测量仪表。作为最基本最常用的声学测量仪器,声级计既是工业生产中作为检测机器工作状态的手段之一,也是环境监测中测量噪声的主要仪器,研究便携的实时声压级测量仪器具有实际的工程应用价值。本课题重点着眼于实时声级计系统搭建和声级实时测量的研究,从测量声级的基本功能出发,在嵌入式Linux操作系统中设计出可移动的便携式声级测量仪器,采用声压传感器、DSP多通道信号分析系统、搭载嵌入式Linux系统的ARM芯片组成实时声级测量系统,将采集的模拟信号转换为数字信号,通过设计的基于DSP的时间计权声级算法和倍频程分析算法,计算出各计权声级和信号频谱,将计算结果上传给ARM进行后续的处理,充分利用了DSP强大的数字信号处理能力,完成了声压级测量分析系统的设计与实现。实验结果表明,所设计出的测量系统能够实现对声压级的实时测量,达到国家标准一级声级计的性能要求。本文在嵌入式技术基础上,对声压级测量技术进行了深入的研究,提出了时间计权声级算法和倍频程分析方法,针对DSP的运算特点对算法进行了优化,使得时间计权声级的运算速度大大加快,倍频程分析算法实现了多频段的同步分析,提高了声级测量的实时性,对于精度也有一定保证,实现了对采集的声压信号的实时处理。实验结果表明,系统在测量精度和测量实时性方面均达到了设计要求,各方面指标符合国家对于一级声级计的要求。
[Abstract]:Acoustics is the science of studying the generation, propagation, and reception of mechanical waves in matter and their interaction with matter. Sound is produced by the vibration of objects (solids, liquids, and gases) when an object vibrates. The surrounding elastic media will be excited to move along with it and form a dense wave in the form of alternating density and propagating outward at a certain speed. The dense wave of this medium is acoustic wave, which will produce pressure on the contact object. People can hear sound because the sound pressure on the eardrum vibration and stimulate the nerve sound level meter is to convert the sound pressure signal into electrical signal and then calculate the sound level measurement instrument. As the most basic and most commonly used acoustic measurement instrument. The sound level meter is not only one of the means of measuring the working state of the machine in industrial production, but also the main instrument for measuring noise in the environmental monitoring. The research of portable real-time sound pressure level measuring instrument has practical application value. This paper focuses on the system construction of real-time sound level meter and the research of real-time sound level measurement, starting from the basic function of sound level measurement. A portable sound level measuring instrument is designed in embedded Linux operating system, and the sound pressure sensor is used to analyze the multi-channel signal. The real-time sound level measurement system is composed of ARM chip with embedded Linux system, which converts the collected analog signal into digital signal. Through the design of time-weighted sound level algorithm based on DSP and frequency-doubling analysis algorithm, each weighted sound level and signal spectrum are calculated, and the calculation results are uploaded to ARM for subsequent processing. The design and implementation of sound pressure level measurement and analysis system is completed by making full use of the powerful digital signal processing ability of DSP. The experimental results show that the designed measurement system can realize the real-time measurement of sound pressure level. To meet the national standards of the first level of sound level meter performance requirements. In this paper, based on embedded technology, the sound pressure level measurement technology is deeply studied, and the time-weighted sound level algorithm and frequency-doubling analysis method are proposed, and the algorithm is optimized according to the operation characteristics of DSP. The calculation speed of the time weighted sound level is greatly accelerated, the frequency doubling analysis algorithm realizes the synchronous analysis of multi-frequency band, improves the real-time performance of the sound level measurement, and also has certain guarantee for the accuracy. The real-time processing of the collected sound pressure signal is realized. The experimental results show that the system meets the design requirements in terms of measurement accuracy and real-time measurement, and all the indicators meet the requirements of the country for the first class sound level meter.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB52

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