Wireless communication from underwater to the air

Jimmy Day

Did you know that submarines today still cannot wirelessly communicate with airplanes? For decades, communicating between underwater and the air has remained an unsolved problem. Underwater, submarines use acoustic signals (or SONAR) to communicate; in the air, airplanes use radio signals like cellular or WiFi. But neither of these signals can work across both water and air.

We present TARF (Translational Acoustic-RF communication), the first technology that enables communication between underwater and the air. A TARF transmitter sends standard sound (or SONAR signals).  Sound travels as pressure waves; when these waves hit the surface, they cause it to vibrate. To pick up these vibrations, a TARF receiver in the air uses a very sensitive radar. The radar transmits a signal which reflects off the water surface and comes back. As the water surface vibrates, it causes small changes to the received radar signal, enabling a TARF receiver to sense the tiny vibrations caused by the underwater acoustic transmitter.

The video below explains how TARF works and some of its applications.

Because TARF uses acoustic signals underwater and radio signals in air, it is able to achieve the best of both worlds. We have tested the system in controlled and uncontrolled settings, included swimming pools with swimmers and circulation currents. The system incorporates new algorithms that enable it to deal with naturally occurring waves, and can successfully and quickly communicate between underwater and the air.

To learn more about how it works, read our paper on TARF.

This project is funded by the Office of Naval Research.