Underwater Acoustic Time-Reversal Mirror

FUNCTION: Records underwater acoustic signals and has the capability to time-reverse and re-broadcast these signals. This provides the ability to focus and scan acoustic energy for the detection of underwater objects. The signals can be emitted from guide sources or received in the form of ocean reverberation.DESCRIPTION: The heart of the system is a 64-element transducer array that can alternately operate as a receiver array or an array of acoustic sources. The time-reversal functionality involves the capability to record signals, reverse them in time, and then re-broadcast them. This provides, for example, the capability to have a received signal returned to its point of origin where it will focus in both time and space. The importance of the concept is that this can be accomplished without detailed knowledge of the complex multipath structure produced by the ocean waveguide. Applications include enhanced echos from target objects, such as submarines or ocean mines, and reduced clutter echos from the ocean bottom or ocean surface.INSTRUMENTATION:64 6-in. spherical source/receive elements in a linear array with 1.25-m spacing (78.75 m aperture)Array elements independently controllable over the 500 to 3500 Hz frequency bandA data digitization and recording systemA pressure vessel to enclose system electronics for bottom-moored deploymentFiber-optic umbilical cable for connection between pressure vessel and ship/surface buoy.