S.M. Jesus sjesus@ualg.pt
and C. Soares csoares@ualg.pt
SiPLAB-FCT, Universidade do Algarve, Faro, Portugal
Comments: download pdf
file .
Ref.: Proc. MTS/IEEE Oceans'01, (ISBN 0-933957-29-7),
p.776-781, Honolulu, Hawai (USA), October 2001.
Abstract : Matched-Field Processing (MFP) is now a mature
technique
for source localization and tracking. There are at least two aspects
that
emerge, by their relevance, to the success of MFP: one is the ability
of
a given MFP processor to accurately pinpoint the source location while
rejecting
sidelobes, and the other is the impact of erroneous or missing
environmental
information (known as model mismatch) in the final source location
estimate.
This study addresses the first aspect regarding sidelobe rejection
while
considering that the processor is working on a mismatch free situation.
One
well known procedure to reduce sidelobes is to use a broadband MFP
processor
(whenever a band of frequencies is available). There are a number of
different
ways to combine MFP information across frequency that can be classified
in
two broad groups: the conventional incoherent methods, that are based
on
the direct averaging of the auto-frequency inner products and the, say,
less
conventional methods, that perform a weighted average of the
cross-frequency
inner products where the weights are the frequency compensation
phase-shifts.
The later are generally termed as coherent broadband methods since they
combine
complex inner products.
The coherent broadband methods proposed in the literature are either
suboptimal
or very computationally intensive, even for a small number of
frequencies.
An alternative method is presented that combines cross-frequency
information
with the same localization performance than the standard coherent
methods
and a computation load similar to that of the incoherent processor. The
performance
of the various broadband processors is compared in simulated data.
ACKNOWLEDGMENT: this work was partially supported by FCT under project ATOMS, contract PDCTM/P/MAR/15296/1999 and by CNR (Italy) under project TOMPACO.