Sonobuoy System and Concept of Operations for Time-Reversal-Based Target Detection Navy SBIR FY2007.1 Sol No.: Navy SBIR FY2007.1 Topic No.: N07-014 Topic Title: Sonobuoy System and Concept of Operations for Time-Reversal-Based Target Detection Proposal No.: N071-014-0827 Firm: Applied Physical Sciences Corp. 475 Bridge Street Suite 100 Groton, Connecticut 06340 Contact: Joshua Wilson Phone: (860) 448-3253 Web Site: www.aphysci.com Abstract: Existing multistatic airborne ASW systems require high power sources and are unable exploit the significant forward scattering target strengths due to the blinding presence of the direct blast. Time reversal (TR) is a recent method for focusing acoustic energy at a point using a pair of vertical line transducer arrays and offers the opportunity to exploit forward scattering from submarines. TR focusing can provide a measure of propagation channel stability, which provides a means for determining when the medium is disrupted as would occur when a scatterer such as a submarine passes between the two arrays. Moreover, because there is significant spatio-temporal focusing gain to be had with TR, there exists the opportunity to use lower power transmissions. Here we propose to determine the feasibility of a TR sonobuoy system for airborne ASW in the frequency band of a DICASS (AN/SSQ-62) sonobuoy and using vertical line arrays similar in dimension to a VLAD (AN/SSQ-77) sonobuoy. Operating at DICASS frequencies allows for achievable array apertures, exploits extremely high forward target strengths (> 50 dB) and improves the sensitivity of the TR. Post Phase I efforts would include implementing modifications to existing sonobuoy hardware for in-water demonstrations. Benefits: If successful, the proposed research would provide a significant improvement in the detection capability of sonobuoy-based ASW systems. This is particularly important in light of the emergence of stealthier adversaries with lower target strengths and the increase in littoral naval operations where acoustic transmission is poor. This research could lead to at-sea tests in Phase II and development for deployment to the fleet in Phase III. UnderSea Sensor Systems Inc. has expressed interest in assisting in Phase II sea trials and in the Phase III transition to sonobuoy development. In addition to air ASW, TRBs may also be applied to other active target detection problems. For example, the Department in Homeland Security is developing multi-static sonar systems for detecting unauthorized divers or submersibles in high-security shore areas like ports and nuclear power plants. APS is currently developing such a multi-static system under HSARPA SBIR Phase II funding (Topic H-SB05.1-004). Return