S.M. Jesus and A. Silva sjesus@ualg.pt
and asilva@ualg.pt
SiPLAB-FCT, Universidade do Algarve
Faro, Portugal
Comments: download pdf file
Ref.: Proc. Conf. on High
Frequency Ocean Acoustics, (Am. Inst. of Physics), Porter,
Siderius and Kuperman (eds), (ISBN:0-7354-0210-8) p.530-538, San
Diego (USA), March 2004.
Abstract : Underwater acoustic communications in waveguides is
known to
be prone to severe multipath, which strongly limitates practical
transmission
rates with actual channel equalization techniques. The time reversal
principle
uses the ocean waveguide response to a basic pulse shape to matched
filter
the received data sequence. Assuming the ocean response to be a version
of
the actual pulse shape ocean response corrupted by additive noise, the
matched
filter output remains a sum of four terms from which only one has the
required
data sequence in useable form. This paper analyses the ability of such
a peculiar
matched filter to reject the unwanted terms both with fixed and
time-varying
source-receiver geometries. One particular parameter with practical
interest
is the sensitivity of the matched filter performance to a drastic
reduction
of the number of acoustic sensors which induces a spatial diversity
limiting
factor. Simulation examples and results obtained with real data,
collected
during the INTIFANTE'00 and the MREA'03 sea trials, are shown to
demonstrate
the theoretical assertions.
ACKNOWLEDGMENT: this work was partially supported by FUP/Ministry of Defence program under project LOCAPASS and AOB - REA Joint Research Project.