Spatial extension of the acoustic time reversal region

Abstract

According to the data of a full-scale shallow-water experiment (in the Barents Sea, at sea depths of about 120 m), a considerable gain in the signal-to-noise ratio is obtained for an acoustic signal received from a source at a distance of 12 km when matching with the medium is performed by the signal from the same source at a distance of 10.5 km. To interpret this experimental fact, a numerical simulation is performed to determine the size of the region of signal focusing due to the time reversal of waves in an ideal waveguide with a soft bottom. It is shown that, for narrowband signals, within a distance of ±5 km along the path from the point of emission of the reversed signal, a regular interference pattern whose maxima are comparable with the principal maximum is observed throughout the whole waveguide depth. For a spectrum width from 100 to 300 Hz, only the principle maximum with an extension of about 100 m is observed at a single depth.