A 1 Mbps Underwater Communications System using LEDs and Photodiodes with Signal Processing Capability

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dc.contributor.advisor Dr. Brian Hughes, Committee Member en_US
dc.contributor.advisor Dr. Leda Lunardi, Committee Member en_US
dc.contributor.advisor Dr. John F. Muth, Committee Chair en_US
dc.contributor.author Simpson, Jim Anto en_US
dc.date.accessioned 2010-04-02T18:16:46Z
dc.date.available 2010-04-02T18:16:46Z
dc.date.issued 2008-12-07 en_US
dc.identifier.other etd-11082007-125028 en_US
dc.identifier.uri http://www.lib.ncsu.edu/resolver/1840.16/2713
dc.description.abstract The inability of radio frequency electromagnetic waves to propagate without attenuation in seawater has traditionally limited underwater communications to acoustics or tethered systems. High bandwidth optical communication systems have been demonstrated for terrestrial and space applications. There is growing interest to see if short range high bandwidth optical wireless systems can be made for the underwater environment. In this thesis we demonstrate a 1 Mbps optical wireless system using LEDs and PIN photodiodes that also incorporates capabilities for signal processing of the received data to be performed. Lasers and Photomultiplier tubes offer high performance, and are generally used in most underwater optical communication systems. However, these components are relatively expensive and can have large form factors. As an alternative solution the much cheaper and more compact LEDs and photodiodes are used as transmitters and receiver components. However, compared to a laser and PMT based system, such a system would be strongly disadvantaged in photon limited environments. If one assumes that photons actually reach the receiver, using signal processing techniques, optimized modulation formats, and error-correction coding, one expects that the range of the system can be extended. The development of a prototype system for the experimentation and verification of this proposition is the main motivation of this thesis. Small, compact transmitters using High Power LEDs and receivers using Si Photodiodes where the data can be digitally sampled such that signal processing techniques can be applied were constructed and demonstrated using a 12 foot, 1200 gallon tank that was also constructed for the project. It was shown that the LED and photodiode based system works well for short ranges, and that advantages can be obtained using digital signal processing. The applicability of this strategy to use digital signal processing techniques can be easily extended to higher performance Laser/PMT based systems. 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 digital signal processing en_US
dc.subject underwater en_US
dc.subject FSO en_US
dc.subject free space optical en_US
dc.subject system en_US
dc.subject LED en_US
dc.subject photodiode en_US
dc.subject wireless communication en_US
dc.subject DSP en_US
dc.subject transmitter en_US
dc.subject receiver en_US
dc.title A 1 Mbps Underwater Communications System using LEDs and Photodiodes with Signal Processing Capability 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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