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dc.contributor.advisorColosi, John A.
dc.contributor.advisorStanton, Timothy K.
dc.contributor.authorJones, Benjamin A.
dc.dateSep-12
dc.date.accessioned2012-11-14T00:02:37Z
dc.date.available2012-11-14T00:02:37Z
dc.date.issued2012-09
dc.identifier.urihttp://hdl.handle.net/10945/17381
dc.descriptionApproved for public release; distribution is unlimiteden_US
dc.description.abstractReverberation, echoes from the water column boundaries and non-target scatterers within the water column, often limits active sonar system performance. Fish can constitute a significant portion of sonar reverberation under certain conditions, such as a horizontally looking sonar system operating at mid-frequencies (19 kilohertz), where scattering by fish with resonant gas-filled swimbladders can dominate over bottom or surface reverberation. This study examines the contributions of various elements of an active sonar system ensonifying aggregations of water column scatterers to determine relative contributions of various physical factors to producing target-like echoes (i.e., clutter). Elements of the system that are considered include 1) a shallow-water waveguide, 2) a stochastic, range-dependent sound-speed profile, 3) a directional acoustic source, 4) a variable scattering response, and 5) an extended scattering volume. Numerical modeling predictions are compared with analytical models and observations. Modeling is validated with long-range, broadband (1.5 to 5 kilohertz) sonar measurements of aggregations of fish in the Gulf of Maine. Key results include the classification of a mixed assemblage of swimbladder-bearing fish, with target-sized aggregations, that produce a significant number of echoes that are at least 15 decibels above background levels. These sparsely distributed scatterers produce highly non-Rayleigh distributions of echo magnitudes that are well-modeled by a computationally efficient, physics-based model.en_US
dc.description.urihttp://archive.org/details/echostatisticsof1094517381
dc.publisherMonterey, California. Naval Postgraduate Schoolen_US
dc.titleEcho Statistics of Aggregations of Scatterers in a Random Waveguide Application to Biologic Sonar Clutteren_US
dc.typeThesisen_US
dc.contributor.departmentOceanography
dc.subject.authorActive sonaren_US
dc.subject.authorshallow-water acousticsen_US
dc.subject.authorwaveguide acousticsen_US
dc.subject.authorecho statisticsen_US
dc.subject.authorsonar clutteren_US
dc.subject.authoractive sonar reverberationen_US
dc.subject.authorbio-clutteren_US
dc.subject.authorscintillation indexen_US
dc.subject.authorK distributionen_US
dc.subject.authortwo-way parabolic equationen_US
dc.subject.authorphasor summationen_US
dc.subject.authorfish aggregationsen_US
dc.subject.authormixed assemblages of fishen_US
dc.description.serviceLieutenant Commander, United States Navyen_US
etd.thesisdegree.nameDoctor Of Philosophy In Physical Oceanographyen_US
etd.thesisdegree.levelDoctoralen_US
etd.thesisdegree.disciplinePhysical Oceanographyen_US


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