Modeling of bio-inspired broadband sonar for high-resolution angular imaging

Abstract

Echolocating mammals perceive images of targets with hyper-resolution and navigate seamlessly through obstacles in complex acoustic environments. The biological solution to imaging with sound is vastly different from man-made sonar. The most prominent difference is that instead of imaging with narrow beams, bats ensonify a large spatial region and exploit broadband echo information to acoustically focus with about one degree of angular resolution. Angular localization may therefore be redefined as a spectral pattern matching problem. By imaging with wider beams, this remarkable performance requires only a single broadband transmitter and two receive elements. Our computational modeling work has led to new insight into the salient spatial information encoded by the bat’s auditory system. Although theoretically not required, spatial localization performance increases with the aid of highly complex baffle structures such as those found in biological sonar. Replicating these bio-inspired baffle structures and acoustic processing techniques in man-made systems can reduce sonar array aperture requirements by a factor of 100 or more for a variety of both aerial and underwater acoustic sensing applications. Recent modeling results are presented along with progress toward the design of a compact bio-inspired sonar system for high-resolution imaging. [Work supported by ONR and NUWC Newport.]