Terrestrial Wi-Fi to Boost Underwater Communications

Modulation can be achieved through a number of schemes, or mathematical algorithms. Two well-known examples are amplitude modulation and frequency modulation used in AM and FM radio. The goal of a modulation scheme is to place the digital data on an analog carrier signal, transmit that signal wirelessly, and then extract the original digital data from the received signal.

“In the world of communication, engineers are always looking for the best performance, to get the most information transmitted, subject to reliability,” said Hanson.

In the electromagnetic space, engineers figured out a modulation scheme that takes a range of frequencies and breaks it up into a bunch of individual subcarriers, and transmits information on all of them simultaneously.  

The best way to pack those subcarriers as close to each other as possible is through OFDM. Interestingly, attempting to do OFDM underwater is more difficult than in the electromagnetic world so it took time for the UConn researchers to work out all the bugs.

“But the result is that OFDM underwater brings some strong advantages, notably that it handles reflected acoustic energy much better than other approaches, while allowing more data to pass through the water. This offers commercial advantages,” said Hanson.

The Storrs, Conn.-based company started gaining traction in 2009 thanks to the SBIR grants, which allowed the concepts to be made into actual prototypes. After being shown as viable in computer simulation and in the lab, the technology was built and tested at UConn’s swimming pool, when the pool wasn’t in use. As part of UConn’s Technology Incubation Program the company maintains close contact with the university, benefiting from student interns and support from regional service providers.

The technology was next tested in regional lakes. Eventually, waterproof housings were built and the technology was tested the shallow waters of Long Island Sound, near UConn’s Marine Science campus.  For this phase of testing, a shallow water housing was used, which consists of a tube of PVC polymer with end caps.  Deepwater housings are very similar, but are typically made of stainless steel, aluminum, or titanium, to handle the extreme pressures at depth, where polymer tubes would be crushed.


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