Sonobuoy System and Concept of Operations for Time-Reversal-Based Target Detection

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.