We can video chat with astronauts aboard the International Space Station and watch live footage from the frozen heights of Everest. But communicating with a submarine (潜艇) or a diver is not so easy. The lack of practical methods for sharing data between underwater and airborne devices has long been a frustration for scientists. The difficulty stems from the fact that radio signals work perfectly in air travel but poorly in water. Sonar(声呐)signals used by underwater sensors reflect off the surface of the water rather than reaching the air.
Now, researchers at MIT have developed a method with the potential to revolutionize underwater communication. "What we've shown is that it's actually feasible to communicate from underwater to the air，" says Fadel Adib, a professor at MJT's Media Lab, who led the research.
The MIT researchers designed a system that uses an underwater machine to send sonar signals to the surface, making vibrations (震动)corresponding to the Is and Os of the data. A surface receiver then reads and decodes these tiny vibrations. The researchers call the system TARF. It has any number of potential real-world uses, Adib says. It could be used to find downed planes underwater by reading signals from sonar devices in a plane's black box and it could allow submarines to communicate with the surface.
Right now the technology is low-resolution. The initial study was conducted in the MIT swimming pool at maximum depths of around 11 or 12 feet. The next steps for the researchers are to see if TARF is workable at much greater depths and under varying conditions-high waves, storms, schools of fish. They also want to see if they can make the technology work in the other direction- air to water.
If the technology proves successful in real-world conditions, expect "texting while diving" to be the latest underwater fashion.
