Rapid assessment of bottom backscattering

Abstract

There is a strong need to obtain information about the expected acoustic reverberation environment that will be encountered in various shallow-water sites to aid in planning and evaluating the effectiveness of operational systems. A new technique is being developed at the SACLANT Undersea Research Centre to quickly sense the mean reverberation levels of a shallow-water area. A prototype device and analysis algorithms have been developed and used as part of rapid response operations. The system transmits and receives acoustic signals from an 80-kHz transducer and simultaneously calculates the quantitative acoustic response of the seafloor. The reverberation measurements made so far have concentrated on mapping the mean seafloor scattering level (backscattering strength) and amplitude statistics over an area for various grazing angle regimes. Differences in scattering strength between high and low reverberation zones within an operational area were significant, with differences in mean level reaching 10–12 dB. Additionally, the reverberation measurements were compared with other techniques to verify relevant bottom-type classification. The experimental technique and data obtained from different areas are presented.