| Summary: | 碩士 === 國立臺灣海洋大學 === 電機工程學系 === 92 === Abstract
Underwater communication is one of the main underwater technologies, actively being developed in many leading countries in the world. When acoustic waves (carrying message) propagate through an underwater channel, they are affected by time-varing multipaths. This generates intersymbol interference in the received signal. Moreover, the wind-induced fluctuation on sea surface and the relative motion between transmitter and receiver will result in a rapid signal phase change. (i.e. Doppler spread effect.) The intersymbol interference and the Doppler spread are the two main factors that significantly reduce the reliability of underwater communication system.
The main objective of this thesis is to study and analyze the parameters of the underwater acoustic channels. Based on the measurement data obtained from underwater communication experiments, channel parameters are estimated by the off-line analysis. Specifications of the underwater communication experiments include transmission distance from 47m to 485m and the transmission rates of 300 bps and 2400 bps. These experiments are performed off the coast of Keelung in order to analyze the characteristics of the shallow and the extremely shallow water areas, such as channel’s power delay profile and its parameter of rms delay spread.
Keywords: underwater communication, acoustic channel, intersymbol interference, multipath, rms delay spread, power delay profile.
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