A 1 Mbps Underwater Communication System Using a 405 nm Laser Diode and Photomultiplier Tube

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dc.contributor.advisor Dr. Brian Hughes, Committee Member en_US
dc.contributor.advisor Dr. John Muth, Committee Chair en_US
dc.contributor.advisor Dr. Robert Kolbas, Committee Member en_US
dc.contributor.author Cox, William Charles, Jr. en_US
dc.date.accessioned 2010-04-02T18:06:29Z
dc.date.available 2010-04-02T18:06:29Z
dc.date.issued 2008-12-07 en_US
dc.identifier.other etd-11082007-124554 en_US
dc.identifier.uri http://www.lib.ncsu.edu/resolver/1840.16/1696
dc.description.abstract Radio frequency communications in seawater are impractical due to high conductivity of seawater limiting the propagation of electromagnetic waves. Current methods, such as acoustic communication, are limited in bandwidth, and the use of cables, such as fiber optic, are expensive and not practical for autonomous vehicles. Underwater tethered communication systems are also very costly to repair if damaged. Optical wireless communications that exploit the blue/green transparency window of seawater potentially offer high bandwidth, although short range, communications. The goal of this Masters thesis was to build sufficient infrastructure to experimentally validate the performance of underwater optical communication systems under laboratory, but hopefully realistic, water conditions. An optical transmitter based on a 405nm blue laser diode was constructed. The transmitter is capable of sourcing 200mA of current to a blue laser diode at speeds of up to 200MHz. The receiver was based on a photomultiplier tube. The high gain and blue/green sensitivity of a photomultiplier tube make it ideal for underwater optical communications. Finally, a 1,200 gallon water tank was constructed that allows the water conditions to be appropriately controlled to simulate an ocean environment Experiments were conducted to validate the design and construction of the receiver, transmitter and water tank. An underwater optical data link was demonstrated that was capable of transmitting data at 500kpbs in return-to-zero format, or 1Mpbs in non-return-tozero format. The transmitted signal could then be optically detected, digitized and stored on a PC for later signal processing. en_US
dc.rights I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. en_US
dc.subject communications en_US
dc.subject optical en_US
dc.subject underwater en_US
dc.subject laser diode en_US
dc.subject laser en_US
dc.subject free space optical en_US
dc.subject PMT en_US
dc.subject photomultiplier tube en_US
dc.title A 1 Mbps Underwater Communication System Using a 405 nm Laser Diode and Photomultiplier Tube en_US
dc.degree.name MS en_US
dc.degree.level thesis en_US
dc.degree.discipline Electrical Engineering en_US

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