Deconvolution of low-frequency ocean-sediment acoustic signals. II. Experimental measurements

Abstract

Bubble pulses generated by wide band explosive sources complicate the interpretation of the arrivals from the ocean bottom. However, these arrivals can be deconvolved to remove bubble pulse contamination and yield the impulse response of the ocean sediment. The deconvolution process is degraded by noise; but methods to reduce the noise sensitivity of the process have been developed as described in the previous paper. These methods were applied to ocean-sediment interacted acoustic signals acquired in a deep-water location. Bottom loss values obtained from the deconvolution process were in close agreement with values computed prior to deconvolution. Furthermore, the deconvolution process enhanced the clarification of the acoustic path structure within the sediment and thereby provided experimental verification of the contention in a previous paper that the interaction of ocean-bottom interface reflected arrivals with subbottom reflected and subbottom refracted arrivals can result in a “negative” bottom loss interpretation. Also, as a result of this interaction bottom loss can be (1) experiment configuration dependent, and (2) processing bandwidth dependent at a given frequency. [This work was sponsored by Naval Sea Systems Command, SEA 06H1-4, A.P. Franceschetti.]