image credit – technewsspace.com
Positioning by GPS and other satellite systems may be accurate on dry land, but they are useless when submerged. Researchers at the University of Illinois at Urbana-Champaign have developed a method to locate it by studying the polarization of light in the ocean.
On land, GPS devices use signals from multiple satellites to figure out where the user is. However, these radio signals are very weak and unstable underwater, even at relatively shallow depths. Because of this, the technology can’t be used by divers, subs, or other things.
Even though sunlight is polarized in water, it goes much deeper than radio waves. For example, the direction of polarization varies a lot on how the light hits the surface, which in turn depends on the date, time, and location.
The team from the university used an underwater camera with special lenses to take about 10 million pictures in different places, like the United States and North Macedonia. The pictures were taken on different days, depths, and times of the day. Then, they were used to teach the neural network to find polarization patterns that could be predicted based on these factors.
Thus, the neural network has trained to distinguish coordinates from underwater photographs within 40-50 kilometers of precision, expecting this to considerably improve as the technology develops. The device is only effective up to a depth of 300 meters since light has a hard time penetrating deeper.
However, the technology may allow for the determination of coordinates below the surface of the water in a variety of environments, including the open ocean, clear or muddy waterways on land, during the day, at night, or at depth. The authors recently reported the study’s findings in the journal eLight.