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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Hardware efficient beamforming and its application to an underwater acoustic data link

Powell, D. G. January 1991 (has links)
No description available.

Bandwidth optimization of underwater acoustic communications systems

Houdeshell, Jack E. 03 1900 (has links)
Approved for public release; distribution is unlimited. / Current underwater acoustic communication systems operate in the frequency band of 1 - 10 kHz and utilize various forms of signal processing to improve data rates. In this work, the influence of the environment on long-range propagation of acoustic signals will be examined over the band of 1-5 kHz. The transmission loss (Th) as a function of range over the bandwidth will be one measure to determine the optimal operating character of the communications channel. Additionally, estimates of signal variance over the bandwidth as a function of range will be computed. The variance will be generated from source platform motion and interface roughness. Particular attention will be paid to the 2 - 4 kHz band of certain operating systems for long-range transmission / Lieutenant, United States Navy

Comparison of channel equalization filtering techniquies in underwater acoustic communications /

Kuchler, Ryan J. January 2002 (has links) (PDF)
Thesis (M.S.)--Naval Postgraduate School, 2002. / Thesis advisor(s): Charles W. Therrien, Kevin B. Smith. Includes bibliographical references (p. 147-149). Also available online.

Direct-sequence spread-spectrum modulation for utility packet transmission in underwater acoustic communication networks /

Duke, Peter S. January 2002 (has links) (PDF)
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, September 2002. / Thesis advisor(s): Roberto Cristi, Joseph Rice. Includes bibliographical references (p. 129-130). Also available online.

Bandwidth optimization of underwater acoustic communications systems

Houdeshell, Jack E. January 2001 (has links) (PDF)
Thesis (M.S. in Engineering Acoustics) Naval Postgraduate School, March 2001. / Thesis advisor(s): Smith, Kevin B. ; Nagle, Daniel T. "March 2001." Includes bibliographical references (p. 39-40). Also Available in print.

Event-driven simulation and analysis of an underwater acoustic local area network

Goh, Meng Chong. January 2010 (has links) (PDF)
Thesis (M.S. in Engineering Acoustics)--Naval Postgraduate School, June 2010. / Thesis Advisor(s): Rice, Joseph A. "June 2010." Description based on title screen as viewed on July 13, 2010. Author(s) subject terms: Communications network, sensor network, acoustic communications, undersea sensors, simulation, Seastar, Seaweb Includes bibliographical references (p. 89-90). Also available in print.

Acoustic interference fields in the ocean

Hurdle, Burton G. January 1988 (has links)
Two areas of underwater acoustics are investigated: ocean-bottom scattering and acoustic fields in geometrically dispersive sound channels. The purpose is to describe and provide an understanding of the physical mechanisms in these two areas by comparing analyzed results from ocean experiments with theoretical computations. Experiments using directive 19.5-kHz transducers illustrate temporal and spacial behavior of signals scattered from the ocean bottom. The signals fluctuate, as a function of acoustic geometry, in linear relation to source and receiver motion and to signal frequency. Spacial structure of the acoustic field depends on frequency and acoustic geometry and is independent of motion and bottom roughness. Data supporting these observations are included as well as data showing the effects of bottom type on the scattered returns, that is, the existence of subbottom returns in some data. Volume-scattering-strength profiles are also provided from data obtained in these experiments. Continuous-wave (CW) and impulsive sources covering frequencies 5 to 260 Hz were towed and deployed respectively over ranges up to 3000 km, with reception on fixed hydrophones. Analyses of measured propagation losses of these low-frequency acoustic signals in the dispersive channel provide insights into the nature of the propagation and the acoustic channel. Both the CW signals and the arrivals of the impulsive signals are analyzed in terms of transmission loss, convergence-zone structure, source-motion effects, interference structure, and channel characteristics. The systematic variation (internal tides) of the medium and its influence on the interference field are discussed. The state of modeling, both simple and complicated, is reviewed and compared with results of the ocean experiments. Relationships are provided between this work and the broader field of underwater acoustics. Suggested areas for future research are made.

The development of an experimental system for insertion loss measurements using a truncated, transient parametric array operating in a wide bore tube

Anastasiadis, Kosmas January 1990 (has links)
No description available.

Detection of binary phase-shift keying signal in multioath propagation /

Jung, Du San. January 2002 (has links) (PDF)
Thesis (M.S.)--Naval Postgraduate School, 2002. / Thesis advisor(s): Charles W. Therrien, Murali Tummala. Includes bibliographical references (p. 83-84). Also available online.

Direct-sequence spread-spectrum acoustic communications with CRV Decomposition /

Angelopoulos, Pavlos. January 2004 (has links) (PDF)
Thesis (M.S. in Electrical Engineering and M.S. in Engineering Acoustics)--Naval Postgraduate School, June 2004. / Thesis advisor(s): Roberto Cristi, Kevin B. Smith. Includes bibliographical references (p. 91-94). Also available online.

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