Accession Number : ADA331857
Title : Long Range Acoustic Communication Based on Optimal Waveform Design
Descriptive Note : Final rept.
Corporate Author : WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
Personal Author(s) : Freitag, Lee
PDF Url : ADA331857
Report Date : SEP 1997
Pagination or Media Count : 49
Abstract : Acoustic communications for long-range underwater applications is made difficult by a number of environmental factors. The most important of these in shallow water propagation is the effect of the large number of ray paths that are observed after the sound travels from the source to the receiver. The summation of these rays at the receiver causes constructive and destructive interference, resulting in spectral shaping that varies over both time and space. The time spread of the channel, which can range from several milliseconds to a large fraction of a second, is the most difficult effect to overcome as the range from the source to the receiver increases. However, given that a phase-coherent system is optimal for maximizing through-put, one can focus on development of the receiver algorithm. In this paper the shallow water channel is first examined and found to have significant time spread over a narrow spread of arrival angles. Next the equalization algorithm is discussed, in particular, aspects which are important for the complex long range shallow water channel.
Descriptors : *ACOUSTIC COMMUNICATIONS, *UNDERWATER COMMUNICATIONS, ALGORITHMS, OPTIMIZATION, WAVEFORMS, ANGLE OF ARRIVAL, SHALLOW WATER, MULTICHANNEL COMMUNICATIONS, EQUALIZATION, ACOUSTIC CHANNELS, PHASE CONTROL.
Subject Categories : Acoustics
Distribution Statement : APPROVED FOR PUBLIC RELEASE