Abstract:
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The presence of noise in the oceans has been growing in the recent years
due to the increasing levels of human activity on the seas. Those activities
include the off shore industry, petrol industry and transport industries. This
noise contamination damages the marine ecosystem. In order to plan human
activities on the seas in such a way that they produce the minimum alteration
to the marine ecosystem it is very beneficial to be able to understand the
relation between anthropogenic and natural process. One the practical side,
this thesis could be the starting point for future technologies that could help
plan human activities in such a way that mitigate the most the impact they
produce on the ocean environment. A part from protection of the ocean
fauna from hearing loss and damage to their sonars this project could also
help researchers to monitor marine fauna. (...) The aim of
this thesis is the classifi cation in real time of underwater frequency modulated
acoustic signals into predefi ned groups. The signals are constrained
into those being frequency modulated because the automatic classi cation
of impulsive sounds has already been subject of considerable study. Apart
from classi cation, clustering of tonal sounds is also a topic of this thesis.
The kind of acoustic emissions that can be found on the underwater environment
in the seas and oceans of the planet come from 3 broad categories,
those categories are biological sources, i.e. dolphins, baleens, etc; anthropogenic
sources, i.e. ship motors, ship sonars, etc; and natural phenomena
like earthquakes and rain. Of those categories, those that produce frequency
modulated tonal sounds are marine mammals and some ship sonars. The underwater signals studied in this thesis are obtained from deep sea
platforms and o ffshore moored stations, and are transmitted wirelessly or
though a cord to coastal computer centers, where the signals are analyzed. |