Playing garbled acoustic messages backwards could take wireless
broadband communication beneath the waves, boosting the speed of data
transfers to submarines, undersea robots and data collection devices by
up to three times.
communication in the ocean is difficult because water molecules absorb
radio waves very efficiently, an effect exploited by microwave ovens.
signals travel better, but also degrade quickly due to echoes, ambient
noise, swirling currents and, again, water absorbing the signals.
a technique called acoustic time reversal can change that. The trick
cleans up underwater sound signals, extending their range and capacity.
William Kuperman and colleagues at the Scripps Institution of Oceanography in La Jolla, California, US, and researchers from the NATO Undersea Research Centre in La Spezia, Italy, have been testing the technique in the Mediterranean.
Reconstructed signal Time
reversal exploits the way undersea acoustic signals typically arrive
clouded by echoes that travel at different speeds. For example, a
"ping" may arrive as three separate sounds