Research Of Noise Spectrum Analysis And Its Application Based On Zoom FFT

The environmental noise pollution has seriously affected people's lives and health.With the growing concern of the society,noise control has gradually been valued by the state and people.The premise of environmental noise control is the accurate measurement and analysis of environmental noises.Environmental noises are broadband random signals with multiple frequency components.In the acoustic measurement,the octave is commonly used for spectrum analysis of noises.In this thesis,two common methods of octave spectrum analysis are analyzed,including the time domain filter bank method and the frequency domain FFT method.The spectrum refinement Zoom FFT algorithm is applied to the frequency domain FFT octave analysis algorithm.The problem of the low frequency error in the domain FFT method gets improved and applied to the real-time noise spectrum analysis system.This thesis consists of five parts.The first one is a review of the research status of domestic and abroad spectrum analysis algorithms of noise and noise measurement systems,as well as the development trend of noise measurement system.The research significance of spectrum analysis algorithm and real-time spectrum analysis system of noise is pointed out.The second one is an introduction of the basic metric and frequency characteristics of noises.The methods of frequency weighting and octave analysis in time and frequency domains are emphasized.The specific implementation steps are given and the shortcomings of the existing methods are analyzed.The third one is the improvement of the frequency domain octave method using the spectrum refinement algorithm and the study of the CZT and Zoom FFT spectrum refinement algorithms.Through simulation comparison and analysis,the Zoom FFT algorithm has lower computational complexity under the same refinement precision,and is more suitable for real-time spectrum analysis system of noise.The 1/3 octave simulation result based on it is given.The fourth one is the design of the system after the analysis of the main functions and performance indicators of the real-time spectrum analysis system of noise.The design scheme and circuit design process of the data acquisition module,the data processing module and the power module are introduced in detail.The last one is the software design of the real-time spectrum analysis system of noise,including the construction of the development environment and the process of the software design.The Zoom FFT spectrum analysis algorithm is applied to the real-time spectrum analysis system of noise which is then subjected to the frequency weighting and 1/3 octave tests.The simulation and test results show that the real-time spectrum analysis system of noise developed in this thesis meets the requirements of GB/T 3785.1-2010 for Class 1 sound level meters.The octave analysis result based on Zoom FFT algorithm meets the requirements of GB/T 3241-2010 for Class 1 filters.The efficiency of the program meets the requirements of the system for real-time performance.