### ASA 127th Meeting M.I.T. 1994 June 6-10

## 1pUW13. Reverberation characterization and suppression by means of
principal components.

**Richard R. Slater
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*Code 7175, Naval Res. Labs., Stennis Space Center, MS 39529
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**Donald W. Tufts
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*Univ. of Rhode Island, Kingston, RI 02881
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A method of reverberation suppression and characterization, called the
principal components inverse (PCI) method, has been used to separate strong
components of the reverberation from the observed data of an active sonar
reverberation experiment. The number of principal reverberation components
needed to represent these strong components seldom exceeds three, illustrating
the fact that, locally in time, segments of the reverberation waveform that
have durations much shorter than a transmitted pulse can be represented as
different linear combinations of the same two or three basis functions. These
basis functions change as we move in time to some other local region. Because
of the interest in the physical structure of reverberation, it is wished that
the reverberation modeled by these basis functions be explained in terms of the
physical components of reverberation models. The PCI method separates a
beamformed acoustic signal into what the PCI method regards as a ``strong
reverberation component'' and ``other components.'' Therefore both the received
signal and the corresponding PCI estimates of the strong reverberation have
been approximated by linear combinations of delayed, scaled, and
Doppler-compressed replicas of the transmitted signal. It was found that the
strong signal components of the observed reverberation and the PCI estimated
strong reverberation match well.