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<p>The objective of this thesis was to analyze data obtained from a network of Ocean Bottom Seismometers to determine if it could be used to provide detailed information regarding merchant vessels such as their direction and draft. The sensors were located in the Strait of Juan de Fuca and collected data from AugustSeptember, 2009. The hydrophone and three orthogonal seismometer channels were beamformed in MATLAB as a vector sensor in an attempt to get bearing data on a passing ship. Frequencies were limited to about 80Hz due to the low sampling frequency. A Lloyds mirror pattern from the ships broadband noise was visible in the lofargrams from all four channels during this transit. The Lloyds mirror pattern was compared qualitatively with theoretical predictions from ray theory as well as with transmission loss predictions from the parabolic equation model run in PC-IMAT. Vector sensor beamforming proved unsuccessful due to the lack of coherence and erratic phase differences among the sensors. This erratic behavior is probably due to multipath effects. Both ray theory and PC-IMAT models show promise for exploiting the Lloyds mirror patterns. The expected interference patterns show a clear dependence on range and draft.
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<br>Subjects: acoustics; interference; vector sensor; Lloyds mirror; lofargram</div>
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Hunt, Richard S.</div>
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