本文關(guān)鍵詞： 聲壓級 實時信號處理 嵌入式Linux 時間計權(quán)聲級 倍頻程分析　出處：《浙江大學》2014年碩士論文　論文類型：學位論文

【摘要】：聲學是研究物質(zhì)中機械波的產(chǎn)生、傳播和接收及其與物質(zhì)相互作用的科學。聲音是由物體(固體、液體和氣體)的振動產(chǎn)生的,當一個物體振動時,就會激勵周圍的彈性介質(zhì)隨之運動,以疏密交替形式并以一定的速度向外傳播而形成疏密波,這種介質(zhì)的疏密波即為聲波,聲波會對接觸物體產(chǎn)生壓力,人能聽到聲音就是由于聲壓對耳膜產(chǎn)生振動而刺激神經(jīng),聲級計就是將聲壓信號轉(zhuǎn)換成電信號然后計算出聲級的測量儀表。作為最基本最常用的聲學測量儀器,聲級計既是工業(yè)生產(chǎn)中作為檢測機器工作狀態(tài)的手段之一,也是環(huán)境監(jiān)測中測量噪聲的主要儀器,研究便攜的實時聲壓級測量儀器具有實際的工程應(yīng)用價值。 本課題重點著眼于實時聲級計系統(tǒng)搭建和聲級實時測量的研究,從測量聲級的基本功能出發(fā),在嵌入式Linux操作系統(tǒng)中設(shè)計出可移動的便攜式聲級測量儀器,采用聲壓傳感器、DSP多通道信號分析系統(tǒng)、搭載嵌入式Linux系統(tǒng)的ARM芯片組成實時聲級測量系統(tǒng),將采集的模擬信號轉(zhuǎn)換為數(shù)字信號,通過設(shè)計的基于DSP的時間計權(quán)聲級算法和倍頻程分析算法,計算出各計權(quán)聲級和信號頻譜,將計算結(jié)果上傳給ARM進行后續(xù)的處理,充分利用了DSP強大的數(shù)字信號處理能力,完成了聲壓級測量分析系統(tǒng)的設(shè)計與實現(xiàn)。實驗結(jié)果表明,所設(shè)計出的測量系統(tǒng)能夠?qū)崿F(xiàn)對聲壓級的實時測量,達到國家標準一級聲級計的性能要求。 本文在嵌入式技術(shù)基礎(chǔ)上,對聲壓級測量技術(shù)進行了深入的研究,提出了時間計權(quán)聲級算法和倍頻程分析方法,針對DSP的運算特點對算法進行了優(yōu)化,使得時間計權(quán)聲級的運算速度大大加快,倍頻程分析算法實現(xiàn)了多頻段的同步分析,提高了聲級測量的實時性,對于精度也有一定保證,實現(xiàn)了對采集的聲壓信號的實時處理。 實驗結(jié)果表明,系統(tǒng)在測量精度和測量實時性方面均達到了設(shè)計要求,各方面指標符合國家對于一級聲級計的要求。
[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.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TB52

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