| Reflecting the physical phenomenon in the process of the typhoon by the ground pulsation data of the seismic stations.In the past,often using linear fitting method to approximate solution of slope to analysis characteristics in the surge propagation,however,error is bigger.The fractional Fourier transform is based on traditional Fourier transform,the time-frequency processing method is put forward.The fractional Fourier transform can break the limitation of the traditional signal analysis and processing,in the joint time-frequency domain on underwater acoustic time-varying signal analysis and processing.This article mainly using the features of detection and information extraction of the linear frequency modulation type signal by the fractional Fourier transform,in the process of the intermediate frequency dispersion effect of pulse signal,through the different periods of dispersion characteristics of signal detection and parameter extraction,verifying the local variation of the dispersion.Combined with the dispersion formula of swell,further analysis of the spread of surge source area.Secondly the article studies the fractional Fourier transform,discrete sampling time and continuous sampling time signal,and the change of the fractional Fourier transform for discrete signal.At last,through the study and simulation experiment of the fractional Fourier transform,based on the discrete fractional Fourier transform,the sliding window fractional Fourier transform is presented,the method can describe the linear frequency modulation type of signal in different rate and initial frequency of the starting time,always can better depict the characteristics of the signal,and apply it to the dispersive effects of pulse signal,this method is also good verified in the dispersion process,verify the characteristics of the dispersion have lots of curves at different times,applied to study the dispersion properties of swell,and the surge of source area are analyzed. |
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