Observation of Acoustical Signal Fluctuations by Time-Frequency Analysis Methods

M. Palmese, A.Bozzo demarinis@dune-sistemi.com
DIBE, Universita di Genova, Genova, Italy
 S.M. Jesus sjesus@ualg.pt
SiPLAB-FCT, Universidade do Algarve
Faro, Portugal
J. Onofre mesquita.onofre@hidrografico.pt
Instituto Hidrografico, Lisboa Portugal
P. Picco
ENEA, La Spezia, Italy
A. Trucco
DIBE, Universita di Genova, Genova, Italy

Comments: download pdf file .
Ref.: Proc. ECUA 2002, (ISBN 83-907591-8-7), p.755-760, Gdansk (Poland), June 2002.

: In this paper, acoustic data collected in shallow water during INTIMATE00 sea trials are analysed with the aim to detect fluctuations in acoustical signals under the effect of a time−varying environment. Some time−frequency analysis methods, i.e., Gabor Expansion and Wigner−Ville Distribution, have resulted to be adequate to find out fluctuations in the received signals, in particular, such analyses reported different time−frequency behaviour in relation with different tidal conditions. The variations observed in the received acoustic data have been compared with the temperature data collected during the sea trials and the related sound−speed profiles: it has been reported that major signals fluctuations over time in the acoustic signal occur in correspondence of the sound−speed profile changes linked to environmental variability.

ACKNOWLEDGMENT: this work was partially supported by projects TOMPACO (CNR, Italy), INTIMATE and ATOMS from FCT (Portugal).