Abstract:
Signals that propagate from submerged sources to deep receivers in the
ocean generally interact less with the fluctuation generation mechanisms near
the sea surface than do clutter signals and noise which originate near the
surface. As a result, signals from submerged sources generally have smaller
fluctuations than clutter signals and noise. The order dependence in the
amplitudes of fluctuations has been used to devise an environmentally adaptive
signal processing algorithm that provides preferential gains for signals having
smaller fluctuation amplitudes than those of clutter and noise [R. A. Wagstaff
and J. A. Mobbs, J. Acoust. Soc. Am. 101, 3027 (1997)]. Gains include increases
in signal-to-noise ratio, clutter suppression, and unalerted automatic
detection. Similar gains can be achieved by exploiting the fluctuations in the
phases of the acoustic pressures in the same manner that the order dependence
was exploited. By replacing the order dependence with phase dependence, a
similar algorithm has been devised that is sensitive to both amplitude and phase
fluctuations and still adapts to the input data. The resulting algorithm,
designated the