FORMAÇÃO PARA USO DAS TECNOLOGIAS DIGITAIS DE INFORMAÇÃO E COMUNICAÇÃO NAS LICENCIATURAS DAS UNIVERSIDADES ESTADUAIS PAULISTAS

Abstract

A recorded signal of blasting vibration was analyzed in time and frequency domain by means of short time Fourier transform (STFT), continuous wavelet transform (CWT), discrete wavelet transform (DWT) and Hilbert-Huang transform (HHT). The analyzed results from STFT with fixed window function and single resolving power could only reflect how the signal energy varied with time approximately and results from wavelet transform (WT) based on wavelet base function and with multi-resolving power could display the attenuation of particle oscillatory intensity in time domain. EMD was a good self-adaptive and effective method, with which Hilbert energy spectrum could clearly express the variation of energy with time and frequency in detail, and most energy was concentrated in a definitive range of time and frequency, but that of wavelet spectrum lines were distributed in a wider frequency range. Therefore HHT was a kind of new time-frequency method for analyzing and processing the blasting vibration signals.