Estimation of Sediment Properties Using Air Launched Sonobuoys

Abstract

The US Navy has been developing its Multi-Static Active Coherent (MAC) acoustic search system. MAC is an air launched acoustic search system that combines a newly developed coherent source sonobuoy with a field of receiver sonobuoys. With the introduction of the coherent source, operational search data collected during MAC exercises are well suited for post-processing to infer waveguide properties. The long term goal of this research is to investigate the feasibility of estimating sedient acoustic properties using data collected during such exercises. OBJECTIVES Modal dispersion data are used in inversion schemes that estimate sediment properties in range independent and range-dependent environments. The experimental scenario for the use of air launched sonobuoys to extract information about the sediment properties in the area covered by the sonobuoys is to have one of the sonobuoys broadcast a broad band signal with a large set of buoys receive these signals. These receiving sonobuoys will be dispersed over a wide area. In such an experimental set up the data acquired by the sonobuoys is used to estimate the sediment properties in the area covered by the sonobuoys. In March 2011, an experiment termed MOMAXV was conducted off the New Jersey coast. In this experiment broad band signals were broadcast from a ship carrying the source. The ship moved to discrete locations around a small set of free-floating buoys. This mimicked the situation where we have a near stationary sonobuoy with a source transmitting a broadband signals and a network of freely floating sonobuoys acquiring the transmitted signals. The objective of the current work is to analyze the data collected during the experiment and estimate the sediment properties of the region between the ship positions and the location of the sonobuoys. APPROACH A. Experiment details MOMAXV was conducted between March 5 and March 18, 2011 off the coast of New Jersey. The complete details of the experiment are described in Frisk et al [1] which is devoted to analysis of narrow band data collected during the experiment. The experiment also included a broad band Report Documentation Page Form Approved OMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.