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A recent paper [H. C. Song et al., J. Acoust. Soc. Am. 127, EL19-EL22 (2010)] demonstrated adaptive time reversal (ATR) using at-sea experimental data which significantly suppressed the cross talk among users (or transmitters) over conventional time reversal. In this letter, the ATR approach is shown essentially equivalent to the least squares solution to an over-determined system. [ABSTRACT FROM AUTHOR]

The primary use of underwater gliders is to collect oceanographic data within the water column and periodically relay the data at the surface via a satellite connection. In summer 2006, a Seaglider equipped with an acoustic recording system received transmissions from a broadband acoustic source centered at 75Hz deployed on the bottom off Kauai, Hawaii, while moving away from the source at ranges up to200 km in deep water and diving up to 1000-m depth. The transmitted signal was an m-sequence that can be treated as a binary-phase shift-keying communication signal. In this letter multiple receptions are exploited (i.e., diversity combining) to demonstrate the feasibility of using the glider as a mobile communication gateway. [ABSTRACT FROM AUTHOR]