Application Of Wavelet Transform And Peak Search-Reconstruction Algorithm In Spectral Analysis Of Signals

In the methods of substance analysis,some methods of measurement are to analyze the properties of a substance by measuring and analyzing the position,height or area of peaks corresponding to the substance.In order to efficiently and accurately detect the information of peak position,peak width and peak height,the denoising method based on waveletthe,the peak signal reconstruction technique based on Gaussian fitting and the peak seeking technique based on derivative combined with inflection point were studied,and the applications in heavy metal detection and ion mobility spectrometry were also given.Wavelet transform is a new-style signal analysis tool.It's based on short-time Fourier transform window function analysis and improves short-time Fourier transform which can't adjust window function width by self-adaption.Compared with wavelet transform modulus maxima method,wavelet transform correlation coefficient method and wavelet threshold method,the wavelet threshold method was chosen as denoising algorithm,which has the advantages of simple program,white noise and sinusoidal noise in spectrum signal,good de-noising effect and wavelet threshold method,and the research focused on the threshold and wavelet basis of the selection.In the selection of the threshold,the Donoho's soft threshold method has been referred and has been improved,adding several parameters so that the threshold can be changed with the decomposition scale changes.At the same time,the wavelet basis functions were selected according to the noise characteristics.By comparing the SNR and RMSE values,several wavelet bases suitable for spectral signal filtering and the relationship between the decomposition scale and the vanishing moment were summarized.Then several algorithms for searching peaks are discussed.In the process of spectral signal analysis,the most critical step is to locate the start and end points of each peak,and then calculate the peak height and peak area based on the peak position.This paper mainly introduced the working principle and characteristics of commonly used peak finding algorithm including comparison method,derivative method,Gaussian fitting method,symmetric zero area method and wavelet transform method.Finally,the application of the peak finding algorithm in instrument design was proposed.The application of the derivative and the inflection point method in the detection of heavy metals was studied.The characteristics of the dissolution peak were studied and the fast peak finding algorithm was designed.The circuit of the potentiometer of the three electrode sensor was developed and the test result and the main parameters were proposed.The denoising method based on Wavelet and the reconstruction techniques of ion migration spectrum based on Gauss fitting method were studied to determine the species and concentration of ion peaks.The test results in the application of ion mobility spectrometry to the detection of explosives were proposed.Experimental results showed that the method of Gauss fitting combining the wavelet de-noising analyzed the signal of ion mobility spectrum can accurately restore the ion peak due to the overlap of signal peaks,and the ability to improve ion mobility spectrometry for the determination of species.