USA As Represented by Secretary of the Navy

Michael T Sundvik

David W Grande

Judith L Bishop

Bernard F Cole

A system for characterizing ocean bottom properties in real-time by explong the multipath structure of reverberation to extract values for the bottom loss and the bottom scattering coefficient. The system obtains environmental and navigational data and synchronizes the data with sonar state data and acoustic beam data to produce an input data stream to an extraction processor. The extraction processor utilizes a digital signal processing means to produce a reverberation energy envelope from the acoustic beam data and time correlate the reverberation energy envelope with the environmental, navigational, and sonar state data. A general purpose computer monitors the reverberation envelope and the environmental, navigational, and sonar state data for change and instructs a modeling processor to construct a new eigenray propagation model and a new reference reverberation model if any changes occur in the data that results in a change to the previously constructed eigenray propagation or reference reverberation models. A pair of local extraction processors perform the extraction of the bottom loss and the bottom scattering coefficient by performing a probe pulse extraction algorithm and a reverberation decay algorithm, respectively.

System and processor for real-time extraction of ocean bottom properties

A method for characterizing ocean bottom properties in real-time by explong the multipath structure of reverberation to extract values for bottom loss and the bottom scattering coefficient. The bottom parameters are extracted from a measured reverberation energy envelope generated from the reverberation returns of one or more pings from a sonar system. The measured reverberation envelope is compared to a reference reverberation model to identify a period of time in which the measured reverberation energy envelope exhibits properties that allow the extraction of bottom parameters. The bottom parameters are then extracted by direct comparison of the measured reverberation to the reference reverberation model within the time period or by iteratively changing the value of bottom loss or bottom scatter coefficient and recalculating the reference reverberation for the identified time period until the reference reverberation matches the representative reverberation. The accuracy of the reference reverberation model is maintained by continuously monitoring the current sonar state configuration and the current environmental parameters including bottom depth, sound speed profile, and wind speed and rebuilding the model should either the sonar configuration or the environmental parameters change in a manner which would cause a change in the model.

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Narragansett, RI, United States of America

Michael T Sundvik