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Making wireless underwater image transmission possible

Wireless technologies are ubiquitous. Cars, planes, woodland campsites, deserted islands—you can connect anywhere. NASA has even installed Wi-Fi access points in space. But one environment has stymied the expansion of digital access. Wireless visual communications simply don’t work underwater. Engineers are working to change that.




Everyone knows that sound and light travel underwater, although water conditions obviously affect the range and clarity. But Wi-Fi is different. The density and movement inherent in any body of water blocks and diffuses the digital waves, so they often don’t end up where they should be. Despite those obstacles, scientists at King Abdullah University of Science and Technology have been working on a system for deep-sea divers, underwater researchers, oil rig repair personnel and others, called Aqua-Fi, that would allow them to share real-time images and footage to computers on the surface via a wireless system attached to their diving gear.

The innovative wireless communication technology is based on the concept of Li-Fi, which uses visible light waves to transmit data wirelessly. The system works by using a device that emits a beam of light that carries the data, which is then received by another device that detects the light and decodes the data. However, since Li-Fi light waves don't travel very far in water, researchers are looking at using a different type of light wave, known as a modulated LED, that can penetrate deeper into the water.

The specific process being tested and refined by the King Abdullah researchers uses radio waves to transmit data just a short distance from the diver's smartphone to a Raspberry Pi—which is just a small computer—attached to their underwater gear. The Raspberry Pi then encodes the images and uses a laser beam to send the data to a computer on the surface that translates the data back into pictures or videos.

The team tested the system by uploading and downloading content between two computers a few feet apart in static water. They hit a maximum data transfer speed of 2.11 megabytes per second and an average delay of 1.00 millisecond for a round trip. According to the researchers, this is the first time the sharing of images via wireless underwater communication has been achieved.

The light-based prototype has several advantages over traditional underwater communication technologies, such as acoustic modems. It can transmit data at higher speeds and with greater reliability, and it is less susceptible to interference from other devices. Additionally, it is less expensive to install and maintain than acoustic modems, which require specialized equipment and skilled personnel to operate.

Several obstacles still need to be overcome before we see real time images wirelessly transmitted from underwater. The researchers note that the light beam must stay aligned with the receiver to work, and this hasn’t been possible in moving water and swimming divers. The original successful test was conducted in clear, still water with the components only a few feet apart. To be of any practical use, the technology will need to work in real-world water conditions and have a much larger range. But it’s a start. And engineers are working to take that start and move it to the finish line.

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