Generalization of the low-frequency surface-reverberation theory to short acoustic pulses in the ocean

Abstract

We analyze surface-reverberation features for short sounding pulses. It is shown that for pulse signals whose length is comparable with the correlation scale of the surface irregularities, the description of the reverberation requires generalization of the Bragg resonance-scattering theory. In such a case, the reverberation intensity in each local area of the statistically irregular surface is determined by a cluster of harmonics of the surface-irregularity spectrum rather than a single harmonic satisfying the Bragg resonance condition. The cluster width is found for pulses with a Gaussian envelope. Integral expressions for the reverberation intensity and frequency spectrum are obtained for narrow-band pulsed signals of arbitrary length. Analogous expressions are also found for wideband complex signals.