Current Search: Modems (x)
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Title
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Design and development of a high-speed underwater acoustic modem.
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Creator
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Alleyne, Jochen Raoul, Florida Atlantic University, LeBlanc, Lester R.
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Abstract/Description
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The design, development and performance of an acoustic modem using spread spectrum modulation techniques in order to reduce multipath interference is detailed in this thesis. The design also includes a method to correct for Doppler shifts in the received data. Finally, error detection and correction are utilized in order to improve the robustness of the transmitted data. The results of field experiments with the modem are used to analyze the performance of the modem under a variety of...
Show moreThe design, development and performance of an acoustic modem using spread spectrum modulation techniques in order to reduce multipath interference is detailed in this thesis. The design also includes a method to correct for Doppler shifts in the received data. Finally, error detection and correction are utilized in order to improve the robustness of the transmitted data. The results of field experiments with the modem are used to analyze the performance of the modem under a variety of conditions. These results are then used as a basis from which to draw conclusions about the spread spectrum technique.
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Date Issued
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1997
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PURL
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http://purl.flvc.org/fcla/dt/15520
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Subject Headings
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Modems, Underwater acoustics
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Format
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Document (PDF)
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Title
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Design of a frequency shift keying array receiver for the acoustic modem.
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Creator
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Boubli, Cecile., Florida Atlantic University, LeBlanc, Lester R.
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Abstract/Description
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Currently, our acoustic modems are used to communicate underwater to Autonomous Underwater Vehicles AUVs. These modems have only one sensor and can transmit at low data rates (from 200 to 1200 bits per second) using Frequency Shift Keying (FSK) modulation. A two-dimensional array receiver (MillsCross) has been developed to receive underwater signals with more reliability, at a higher data rate (about 30,000 bits per second). This array has been designed to operate with Phase Shift Keying...
Show moreCurrently, our acoustic modems are used to communicate underwater to Autonomous Underwater Vehicles AUVs. These modems have only one sensor and can transmit at low data rates (from 200 to 1200 bits per second) using Frequency Shift Keying (FSK) modulation. A two-dimensional array receiver (MillsCross) has been developed to receive underwater signals with more reliability, at a higher data rate (about 30,000 bits per second). This array has been designed to operate with Phase Shift Keying modulated signals. The purpose of this thesis is to design and implement a signal processing software to demodulate and decode FSK signals acquired by the MillsCross. By taking advantage of the spatial gain of the MillsCross receiver array, higher reliability and longer ranges are expected using FSK, in addition to achieving compatibility between the two systems. This software includes a robust synchronization scheme, a spatial and an equalizing filter, a time-window self-adjusting process and the error control decoding.
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Date Issued
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2000
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PURL
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http://purl.flvc.org/fcla/dt/15788
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Subject Headings
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Underwater acoustics, Modems, Signal processing--Digital techniques
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Format
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Document (PDF)