Research Of Real-time Noise Measurement System Based On ?C/OS-?

With the development of industrialization,noise pollution is becoming increasingly prominent and has brought a series of adverse effects.Effective control of noise pollution is one of the major problems we are facing today.The research on noise measuring accurately has very important significance.Precise and real-time noise measurement system are preconditions to acquaint,analyze,and process various noise problems.The accuracy of the real-time noise measurement system must be guaranteed to get the accurate analysis results,and also can analyze the frequency composition of the noise signal in real time.The design of reasonable embedded hardware scheme can make the system process and analyze about the noise data rapidly.So,this thesis researches into the main analysis algorithm of noise measurement and the concrete realization method of the system,which is aimed to present a real-time noise measurement scheme with high accuracy,good real-time performance and strong operability.In the thesis,since the frequency distortion exists in the design of frequency weighting digital filter based on bilinear transformation,an evolutionary method based on modified Imperialist Competitive Algorithm has been proposed to design IIR filter,and a chaotic function which is aimed to make the search range wider in the assimilation operation of ICA is introduced.Meanwhile,a clone evolution operator is presented in the competition operation,guiding the search for global optimization efficiently.Then,the optimization model of modified ICA and objective function of the filter are designed according to the source of error in frequency weighting IIR filter,and the filter coefficients are searched based on the modified ICA.This thesis builds a hardware platform of DSP+ARM,and transplants the ?C/OSII operating system to the ARM of the real-time measurement system,which is aimed to realize the real-time measurement and spectrum analysis of noise,and the system with high real-time performance and processing efficiency can also provide friendly human-computer interactive operation.The DSP is responsible for the computation of the spectrum analysis and frequency weighting digital processing of noise signal,and the ARM undertakes the system management work and displays the measurement results in real time,including communication with the upper-computer.The ?C/OS-? divides the application layer into multiple tasks,and it can manage the tasks by calling the application program interface of the operating system to access the hardware platform.Meanwhile,its characteristics with high response speed and reliability can effectively achieve the real-time design and human-computer interactive optimization of the measurement system.The simulation and experimental test about the spectrum analysis and the frequency weighting characteristics at the different acoustic signal level,showing that the design of digital filter banks satisfy the requirements of the GB/T 3241-2010 for Class 1 filters,and the frequency weighting digital filter in this thesis can reduce nonlinear error of bilinear transformation in the high frequency.The optimization effect is obvious,and it can improve the measurement precision in real time noise measurement system.