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Advisor(s)
Abstract(s)
This work presents a technique for reducing the intersymbol interference (ISI) in underwater
coherent communications using time-reversal acoustics. The paper introduces a “virtual"
time-reversal mirror (TRM) that is implemented electronically at the receiver array and
simulates the kind of processing that would be done by an actual TRM during the reciprocal
propagation stage. In both cases, a probe pulse sent by the transmitter/receiver located at the
(physical or virtual) focal point and received at the array provides a template impulse
response for undoing the effects of multipath by straightforward linear filtering. Very simple
equalization algorithms may subsequently be used to decode the message.
Channel variations between transmission of the probe and the actual message lead to
mismatch that can impact the coherence of TRMs, and hence degrade the focusing power of
the array. Computer simulations using a normal-mode propagation model in a reallistic
shallow water scenario show that, even with high uncertainty in the transmitter and receiver
relative positions, the virtual mirror can strongly reduce the effects of multipath. Although a
multichannel equalizer attains a lower mean-square error, the "virtual" TRM can provide
comparable results under low mismatch with much smaller complexity.
Description
Keywords
Underwater acoustics Time-reversal mirror
Citation
A. SILVA, J. GOMES, S.M. JESUS e V. BARROSO, ''Underwater Acoustic Communication Using a Time-Reversal Mirror Approach" in Chevret, P. e Zakharia, M.E. (Eds.) "Proceedings of the Fifth European Conference on Underwater Acoustics, ECUA 2000", 2000, pp.531-536.