A W S U M EAP: An environmentally sensitive adaptive fluctuation-based processing algorithm that exploits amplitude and phase

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 AWSUM environmentally adaptive phase (EAP) is described, and results from measured data are presented. [Work supported by ONR and NRL.]