Researchers at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have discovered a method of packing more channels onto a single acoustic frequency — massively increasing the quantity of data that can be transmitted underwater.
“Image you are somewhere underwater in the ocean — say, you are on a submarine — and still want to communicate with high speed with other submarines, or surface vessels, or somewhere on ground,” Chengzhi Shi, a PhD student in Mechanical Engineering, University of California, Berkeley, told Digital Trends. “The cell phone, Wi-Fi, and other microwave-based communication network we use everyday [don’t work] because microwaves can be easily absorbed by water. Some may think about optical waves, but light has a tiny wavelength that can be easily scattered by micro-particles and marine life in the ocean and the information gets lost.”
It’s for this reason why SONAR acoustic waves are currently the only medium used for underwater applications. The problem? That the frequency of the acoustic waves is so low that it limits communication speed to around a kilobit per second. To put that in perspective, average broadband speeds are around 50 megabits per second (50,000 times as fast).
With their new setup, Berkeley researchers were able to simultaneously pack eight channels onto an acoustic frequency, rather than just the one. This means sending 8 bits at the same time, or an increase of 8x the current rate. In the words of the researchers, it’s “comparable to going from a single-lane side road to a multi-lane highway.” In their experimental setup, the investigators sent data through the air, but using frequencies very similar to the ones required to convey information in the water.
The research means a lot more than just faster Apple Music downloads for people stuck on submarines, though. The slow speed of underwater communication is one of the reasons so much of the ocean remains uncharted. Faster communications will play a vital role in subjects like seafloor mapping using unmanned vehicles and underwater robots, as well as things like offshore oil surveying and vessel detection. If this work lives up to its potential, it could represent a seismic leap for all of these areas.
“The next step is to actually put our transducer array underwater to test the communication method in the real-water environment,” Shi said. “We are planning to do so soon. Once the technique is tested underwater, we can then commercialize our work.”
A paper describing the work was recently published in the journal PNAS.
