Researchers develop way to revolutionise underwater communications

Massachusetts Institute of Technology (MIT) researchers have developed a way of sending signals from underwater to airborne devices; which could revolutionise underwater communications and marine research. In the past, communicating with a submarine or a scuba diver from land or air has been difficult, and there has been a lack of procedure for sharing data between the two. But all that could be about to change.

Transmitting signals underwater is considered more difficult than through the air, as they require a different type of signal; which is not as easily transmitted. Radar signals, radar being short for Radio Detection and Ranging, are most commonly used on land or in the air and use radio waves; which is a type of electromagnetic energy. Radar signals send a radio pulse into the air, of which some is reflected by objects. These reflections are then captured by a receiver and the speed of the moving objects can be calculated using the Doppler Effect. The Doppler Effect is described as a change in frequency and wavelength of a wave, it is caused by the change in distance between the thing creating the wave (known as the causer or sender) and whatever is measuring seeing or hearing the wave (also known as the watcher or observer). Sonar signals, sonar being short for Sound Navigation and Ranging, are commonly used underwater and often by submarines and divers. They use a type of acoustic energy known as a sound wave and use a similar process as radio waves; however, because they reflect off the surface of the water, they struggle to reach the air above the surface. Both radar and sonar rely on the speed of sound but sound waves travel at a much slower speed underwater than on land or in the air. Because of the variables between transmitting signals underwater and in the air, communication between the two has been a development-in-waiting, bringing much frustration to scientists, engineers, divers and military officials.

But recently, MIT researchers managed to design a system that uses an underwater transmitter to send sonar signals beyond the surface of the water, making vibrations which the receiver above the surface can read and decode. MIT have named the system ‘TARF’ which stands for translational acoustic-RF communication.

This new technology will be beneficial in many real-world scenarios, but it could be particularly helpful in enabling submarines to communicate with entities above the surface, making marine research much simpler, enabling scientists to send data from underwater sensors to the airborne receiver in real time. The transmitter could also be used to find aeroplane debris by reading the sonar signals from the plane’s black box.

Fadel Adib, a professor at MIT’s Media Lab who led the research, says, “It’s very difficult to monitor the ocean, which is why most remains unexplored. Using this technology, you could now deploy sensors and do continuous monitoring, sending data to the outside world in real time. You could study marine life and have access to a whole new world that is still pretty much out of our reach today.”

The transmitter is still under development and, right now, is still low-resolution, but one day it could be developed to stream video that could revolutionise marine research. It has been tested as a concept in the MIT swimming pool at maximum depths of approximately 11 or 12 feet and the next steps are to test it to operate at tens or hundreds of thousands of meters.

MIT researchers are also testing the technology to see how well the transmitter will work under stressful conditions, such as high-waves, storms, and in different natural occurrences under the water, such as swimming schools of fish.

So far, the transmitter has only proven to work by sending signals from underwater to an airborne receiver, but the researchers will also be seeing if they can make the technology work the other way around, from air to water, which would allow scientists to send and receive data to underwater devices or for aeroplane pilots to communicate with submarines and divers.

Find out more about the new technology.

Tags: EMC Testing, marine

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