Transformada de Hilbert-Huang Modificada com Redução do Ruído para Sinais de Sonar Passivo

The Hilbert-Huang transform (HHT) is a time-frequency (TF) analysis technique based on empirical mode decomposition (EMD), which has been successfully applied to non-stationary signals and non-linear systems, including passive SONAR signals. However, the performance of HHT/EMD can be greatly degraded under conditions of low signal-to-noise ratio (SNR). The present work proposes a TF analysis method for passive SONAR signals based on HHT/EMD, in which noise reduction is performed by analyzing the autocorrelation function (ACF) and the wavelet threshold denoising (WTD), performed after EMD. The results obtained with experimental passive SONAR signals are used to validate the proposed method.