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Shallow-water acoustic communication with high bit rate BPSK signals

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Author: Gijzen, M.B. van · Walree, P.A. van
Type:article
Date:2000
Publisher: IEEE
Place: Piscataway, NJ, United States
Institution: TNO Physics and Electronics Lab, Hague, Netherlands
Source:Oceans 2000 MTS/IEEE, 11-14 September 2000, Providence, RI, USA,, 3, 1621-1624
Identifier: 235745
Keywords: Acoustic signal processing · Carrier communication · Communication channels (information theory) · Equalizers · Hydrophones · Least squares approximations · Phase shift keying · Underwater acoustics · Binary phase shift keying · Least square equalizer · Pseudo random learning sequence · Shallow water acoustic communication · Oceanography

Abstract

BPSK signals have been defined for transmission through a shallow-water acoustic communication channel. The signals were accompanied by two displaced carriers to facilitate carrier recovery. To correct for the adverse effects of time spreading, a pseudo-random learning sequence was transmitted ahead of the communication signal. The signal processing consists of a shift to baseband guided by the displaced carriers, a least-squares equalizer tuned to the received learning signal, coherent addition of reconstructed baseband signals (corresponding to selected channels of the receiving hydrophone array), and bit restoration with a decision-directed equalizer. In this manner, bit rates up to 4 kbit/s are successfully dealt with in moving-point-to-fixed-point communication. The main risk appears to be the fading of a displaced carrier.