Research On Real-time Measurement Method And Application Of Environmental Noise

Environmental noise is the sound impairs the living environment which arising from industrial production, construction, transportation and social life. Environmental noise pollution has become an increasingly serious problem with the rapid development of modern social economy and the increase of human activities. The important prerequisite for the effective control of environmental noise pollution and reduction of the harm of environmental noise is the accurate measurement and analysis of environmental noise. Meanwhile, the equipment of environmental noise measurement has been widely applied in various fields of environmental noise monitoring with the increase of the whole society to environmental concerns and noise pollution prevention and control efforts of environmental noise.In this thesis, the method and application of environmental noise measurement and analysis are studied in two aspects, which is to develop a system for real-time measurement and analysis of environmental noise. The optimization design of the measurement methods which of the frequency weigting time,time weighting octave analysis and the design of hardware circuit and software of the system are included in this study.An optimal design of A/C frequency weighting based on the Seeker Optimization Algorithm (SOA) is proposed according to the error of A/C frequency weighting based on bilinear transform.Acoording to using the crowd as the search group intelligence and the search optimization of IIR filter coefficients of A/C frequency weighting,the optimization design is finally realized. Based on the method of differential approximation, digital derivation of time weigting is given. The method of down sampling is used to reduce the computation of the frequency doubling process aiming at the problem of large amount of computation of the octave analysis based on the digital filter. At the same time, the design flow of the octave digital filter bank based on Matlab and digital derivation of time weighting is given.In this thesis, a DSP and a MCU are used to play the role of algorithm execution core and management core seprately, then the whole system circuit is divided into several modules according to the function, and the detailed circuit design is given. Finally, frequency weighting, time weighting, octave analysis program flow chart is given, while the above program run time for analysis according to the design of the system software.The simulation and testing experiment is carried out on the frequency weighting and time weighting. The simulation and testing results show that the error of frequency weighting and time weighting satisfies requirements of the GB/T 3785.1-2010 of the sound level meter. Octave filter error satisfies requirements of GB/T 3241-2010 for Class 1 filters.The 1/3 octave analysis can meet real-time requirements of the system according to the analysis of the program running time.