碩士 / 國立海洋大學 / 電子工程學系 / 81 / The energy of high-frequency electromagnetic wave decays rap-
idly when it is propagated in water;hence the electromagnetic
w- ave is not adequate to underwater communications.In this
thesis, techniques of underwater data transmission using
acoustic wave and maximal length sequences (m-sequence) are
investigated. The m-sequence coding method is popularly adopted
by spread spectrum communication.Combining the m-sequence
generating circuits,Freq- uency-shift keying(FSK) modulation
and demodulation modules,and some other processing units,we
build up a simple underwater data transmission prototype
system. The study of multipath fading phenomenon is an
important top- ic for underwater acoustic communications, and
it is discussed in this thesis,too. The SPW (Signal Processing
Worksystem), a w- ell-known computer simulation software for
communication system design, is employed in simulations of
Rayleigh channels and the direct sequence spread spectrum
system.Several FSK spread spect- rum communication examples
using different PN (pseudo-noise) se- quences are studied in
detail.Experiment results as well as the data obtained in the
simulation demonstrate that the proposed t- echniques are
efficient.
| Identifer | oai:union.ndltd.org:TW/081NTOU0428006 |
| Date | January 1993 |
| Creators | Yen Shan Yeh, 葉炎山 |
| Contributors | Fwu Sheng Leu, 呂福生 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 90 |
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