Underwater acoustic swept carrier communications

Barbour, Robert Leslie (1979) Underwater acoustic swept carrier communications. Masters thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (32MB)

Abstract

Underwater acoustic communication is severely affected by multipath interference. A novel idea based on the observation that the time separation between direct and multipath signals can be utilized to suppress multipath interference is developed in this thesis. -- A proposed system employs a carrier with instantaneous frequency swept periodically in time over a broad frequency range. The carrier is narrowband modulated by a message signal resulting in a time varying instantaneous spectrum of the transmitted signal. The received signal is demodulated by a bandpass tracking receiver. The low sweeping frequency determines the multipath spectrum and the degree of multipath suppression by the tracking bandpass receiver. -- Computer evaluation of the swept carrier concept together with lab and field tests conducted on a system prototype show conclusively that swept carrier communication is a feasible technique for multipath interference suppression.

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