Results of Basic At-Sea Experiments on Time-Reversal Communication in the Deep Ocean

In out research program, research and development on a long cruising autonomous underwater vehicle (AUV) are promoted. In such AUV operation, it is very significant to establish acoustic communication even at low data-transmission rate. Time-reversal techniques have a possibility to realize such long horizontal communication, which converge multipath signals to the focus, decrease intersymbol interference (ISI). We have researched on time-reversal communication in the deep ocean. To verify the performance of such time-reversal communication, at-sea experiments, at the range of 20, 30 and 40 km in the Suruga trough, and 100 km at a water depth of 4,000 m in outer ocean, were executed following our first experiments. In these experiments, the convergence of a probe pulse by passive time reversal is confirmed, and based on these converged pulses, time reversal communication performance is investigated.