MIT researchers break water-air barrier so submarines can talk to airplanes

It's been impossible to communicate directly between the two mediums, water and air, until now.

Voices underwater can’t be heard on the ground, and this is because sonar waves or sound waves are used for communication underwater, and radio waves are used to communicate on the surface. So far, communication between underwater devices and the outside world has been impossible. But it looks like researchers at Massachusetts Institute of Technology might have an answer, with a new technology called 'translational acoustic-RF communication' (TARF).

You might wonder why the technology is important anyway. For years, it has been a challenge to make direct data transmission between underwater devices and airborne devices – more specifically the communication between submarines and airplanes. As of now, there is no possible way for these two to communicate with each other directly.

Wireless communication breaks through water-air barrier. Image: MIT

Wireless communication breaks through water-air barrier. Image: MIT

Above water, communication happens using radio waves, which can travel hundreds of kilometres. Underwater however, radio waves do not work. They travel just a few inches and finally die. This is why sound waves are used by submarines and divers to send messages. Since the two mediums use completely different forms of waves, it’s been difficult to figure out a solution. Plus, the surface of the ocean is a tough barrier for any kind of signal to cross.

Researchers at MIT seem to have developed a solution called TARF, which involves underwater sound waves to create vibrations which can be detected on the surface. Here’s how it works. An underwater transmitter directs a sonar signal to the water’s surface. This causes causing tiny vibrations on the surface of the water. Above the water surface, a highly sensitive receiver reads these vibrations or disturbances and finally decodes the sonar signal. What is great is that TARF doesn’t really require a perfectly still water surface.

Check out a video that they posted.

The idea was presented in a paper at MIT’s SIGCOMM conference. “Trying to cross the air-water boundary with wireless signals has been an obstacle. Our idea is to transform the obstacle itself into a medium through which to communicate,” says Fadel Adib, an assistant professor in the Media Lab, who is leading this research. He co-authored the paper with his graduate student Francesco Tonolini.

The technology can prove highly useful to military submarines, for instance, who wouldn’t need come all the way to the surface of the ocean to communicate with aeroplanes. Doing so compromises their location. Also, there are underwater drones that are used for monitoring marine life, that would no longer need to resurface from deep dives to communicate with researchers.

The researchers have also said that the application of the technology could go as far as aiding searches for planes that go missing underwater.

While the technology is only in its early stages and being tested in indoor pools, MIT hoped to make it for possible in rough ocean waters.

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