First Advisor

Lisa M. Zurk

Date of Publication

Spring 1-1-2012

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Electrical and Computer Engineering

Department

Electrical and Computer Engineering

Language

English

Subjects

Cross-correlation, Hyperbola, Localization, Passive Acoustic Vessel Localization, Acoustic localization, Time delay systems -- Design and construction, Sonar

DOI

10.15760/etd.757

Physical Description

1 online resource (xi, 58 p.) : col. ill.

Abstract

This thesis investigates the development of a low-cost passive acoustic system for localizing moving vessels to monitor areas where human activities such as fishing, snorkeling and poaching are restricted. The system uses several off-the-shelf sensors with unsynchronized clocks where the Time Difference of Arrival (TDOA) or time delay is extracted by cross-correlation of the signal between paired sensors. The cross-correlation function uses phase correlation or Phase Transform (PHAT) which whitens the cross-spectrum in order to de-emphasize dominant frequency components. Using the locations of pairs of sensors as foci, hyperbolic equations can be defined using the time delay between them. With three or more sensors, multiple hyperbolic functions can be calculated which intersect at a unique point: the boat's location. It is also found that increasing separation distances between sensors decreased the correlation between the signals. However larger separation distances have better localization capability than with small distances. Experimental results from the Columbia and Willamette Rivers are presented to demonstrate performance.

Rights

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Comments

Portland State University. Dept. of Electrical and Computer Engineering

Persistent Identifier

http://archives.pdx.edu/ds/psu/8299

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