Air Antisubmarine Warfare Environmental Characterization Using Existing Tactical Sensors

Air ASW search rates are critically dependent upon source-receiver separations, which are in turn driven by acoustic propagation and noise characteristics. To optimize the search rate, an accurate environmental assessment must be performed. The currenttechniques of using monostatic reverberation to invert for scattering strength and geo-acoustic parameters is fundamentally limited by the fact that all reverberant energy must propagate from the source to the bottom and then back to the receiver. Atechnique is proposed to simultaneously invert monostatic reverberation and direct blast propagation recordings using existing sources and sonobuoys. A physically consistent sediment model is used to permit extrapolation of acoustic predictions infrequency or source/receiver depths. ORINCON proposes to couple this environmental characterization with the development of a search-update algorithm to permit the optimization of air ASW search rates via the incorporation of tactical acoustic data takenwhile conducting the search, rather than during a preflight environmental characterization. In Phase I of this research, the self-consistent inversion approach, using tactical data and the search-update rule set, will be developed. These will beincorporated into the Geo-Acoustic Inversion Toolbox (GAIT) program of SPAWAR PMW-155 during Phase II and demonstrated at-sea, in real time, using existing tactical sensors. Optimal deployment of current Navy air-deployed ASW systems in the littoral islimited by the sensitivity of acoustic propagation to environmental parameters. A hybrid approach is presented which utilizes acoustic information taken during a submarine search to update the search pattern and therefore optimize search rates. Withinthe Navy, there is a wide base of customers with interest in technology that can characterize an environment concurrent with the conduct of an active acoustic ASW search. The technique proposed can be extended to other active acoustic environmentalapplications, such as oil exploration, marine mammal mitigation studies, and ocean acoustic tomography.