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Application of wavelets for analysing ship noise from shallow water ambient noise measurements

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Title Application of wavelets for analysing ship noise from shallow water ambient noise measurements
 
Creator Ashokan, M
Latha, G
Durai, P Edwards
Nithyanandam, K
 
Subject Time series
Fast Fourier Transform
Power Spectral Density
Wavelet
Wavelet packet
 
Description 11-16
Time series measurements of shallow water
ambient noise have been made for a week, off Tuticorin by deploying an
autonomous ambient noise measurement system. Preliminary analysis of
measurements showed that predominantly the noise field is due to ship crossing
other than the wind noise. This paper presents the work carried out in
extraction of specific ship noise sources by application of wavelet transforms
as wavelet denoising algorithm has finer decomposition and reconstruction
properties in the frequency domain. Frequency localization of wavelet denoising
technique is used to efficiently localize the ship noise. Methodology involves
study of spectrogram of the noise measurements initially and then application
of wavelet decomposition (down sampling). Optimal threshold value for the
wavelet coefficients is calculated and this yields 2(2n-1) levels to denoise
the signal. From the wavelet coefficients, reconstruction (up sampling) of the
decomposed signal is performed. Finally the spectrogram of the reconstructed
signal is studied. Results show clearly the narrow band frequency components of
shipping noise present. This has applications in finding different types of
boats/ship noise and the technique is applied to different data sets for
finding such sources.
 
Date 2014-02-05T09:18:19Z
2014-02-05T09:18:19Z
2014-01
 
Type Article
 
Identifier 0975-1033 (Online); 0379-5136 (Print)
http://hdl.handle.net/123456789/26418
 
Language en_US
 
Rights CC Attribution-Noncommercial-No Derivative Works 2.5 India
 
Publisher NISCAIR-CSIR, India
 
Source IJMS Vol.43(1) [January 2014]