S.M. Jesus sjesus@ualg.pt
SACLANT Undersea Research Centre,
Viale SAn Bartolomeo 400,
I-19138 La Spezia, Italy.
Comments: download pdf
file .
Ref.: Journal of the Acoustical Society of America,
93(4), Pt.1, p. 1841-1850, 1993.
Abstract
Range and depth source localization in shallow water amounts to the
estimation of the normal-mode structure of the acoustic field. As
``seen''
by a vertical array, and from a modeling point of view, the normal-mode
structure appears as a set of non-plane coherent waves closely spaced
in vertical angle. This paper presents a full-wavefield narrowband
high-resolution technique that uses the spectral decomposition of the
sample covariance matrix to resolve the vertical arrival structure of
the harmonic acoustic field. The broadband processor is obtained by
weighted
averaging of the narrowband range-depth ambiguity estimates within the
source
signal frequency band. Results obtained on synthetic data show that its
performance is always better than or equal to that of the generalized
minimum variance processor, which itself largely outperforms the
conventional
matched-field processor. It is shown, using both simulated and
experimental
data, that the effect of the broadband processor is to increase the
stability of the source location estimate. Results obtained with this
processor on short transient pulses collected during the North Elba'89
experiment with a 62 m aperture vertical array, showed stable and
accurate
localizations over long time intervals. It is also shown that the sound
field, received over a given frequency band, is relatively stable over
time and is in agreement with the predictions given by a standard
normal-mode propagation model.