Aqua-Fi could bring Wi-Fi-like tech to the underwater world

Aqua-Fi could bring Wi-Fi-like tech to the underwater world
A diagram illustrating how the Aqua-Fi system would work
A diagram illustrating how the Aqua-Fi system would work
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A diagram illustrating how the Aqua-Fi system would work
A diagram illustrating how the Aqua-Fi system would work

Radio waves travel poorly through the water, which makes it difficult for divers or submersibles to wirelessly transmit information to the surface. Scientists are trying to change that, though, by developing an underwater version of Wi-Fi.

Back in 2018, we heard how researchers at Saudi Arabia's King Abdullah University of Science and Technology (KAUST) had used lasers to transmit HD video through water. Their experimental new system, known as Aqua-Fi, builds on that technology.

A user such as a scuba diver would start by sending data (such as photos or videos) from a smartphone contained in a watertight housing. That data would initially be transmitted in the form of radio waves, going just a few feet to a small device mounted on the diver's air tanks.

A microcomputer in that device would then convert the data into a series of ultra-rapid light pulses, each pulse representing either a 1 or a 0 in binary code. Those pulses would subsequently be emitted towards the surface, using either an integrated 520-nanometer laser or an array of green LEDs – the LEDs could send the data relatively short distances using little power, while the laser could send it farther but would use more power to do so.

Upon reaching the surface, the light pulses would be received by a photodetector on the underside of a ship, then converted back into the original photos or videos by a connected computer. From there, the files could be uploaded onto the internet via satellite.

So far, the Aqua-Fi system has been used to upload and download multimedia between two computers placed a few meters apart in still water. Before it can enter real-world use, though, it will have to be adapted to meet challenges such as the light-scattering effect of swiftly moving water – doing so may involve utilizing a spherical receiver, that could detect light pulses coming in from all directions.

"We have created a relatively cheap and flexible way to connect underwater environments to the global internet," says the lead scientist, Assoc. Prof. Basem Shihada. "We hope that one day, Aqua-Fi will be as widely used underwater as Wi-Fi is above water."

The research is described in a paper that was recently published in IEEE Communications Magazine.

Source: KAUST

Sharks are able to (instantly) detect tiny electric field (voltage) changes in sea water from great distances! So, maybe that is the best practical solution, for undersea communication (a communication device that can produce & detect tiny voltage changes) & NOT lasers nor ultrasound nor ELF!
For any significant distance, it seems that blue light would give you the best transmission. For the short-range link, maybe red is best for signal-to-noise because there isn't much red from the surface down there.
That's really cool stuff for them blue oceans, but a lot of real diving -- the kind that might really need this kind of tech -- happens with absolutely horrible visibility. Good luck with this stuff on a day when visibility is less than an arms length.
Brian M
Probably not going to work very well in a real diving situation, possible for fixed point to point - but then might as well just use a cable! Perhaps some sort of Quantum entanglement radio - but even that looks unlikely
Expanded Viewpoint
This might work in fresh water lakes and rivers, but there's so much organic debris in the ocean, the S/N ratio is going to be horrible! And then add into the mix different water temps (thermocline) and varying salinity which will give you even more scattering and attenuation, and you might as well use two tin cans and some fishing line in between them! How about using high frequency sound waves? Water is nearly incompressible, so sound waves travel great distances. The S/N ratio may not be too high, unless there's a storm raging nearby.