GPS technology has become an indispensable ally in every trip. At least on the surface of the earth. Because when it comes to the underwater world, the rules change drastically. The problem lies in the fact that the radio waves of this satellite technology degrade rapidly in water. If you want to travel along the bottom of the Mediterranean Sea, you’re better off relying on sound waves, or sonar. But at the moment there is another pitfall. It takes a lot of energy to emit sound waves. Submarines are fine, but devices that track sharks, whales, etc. require batteries. These creatures spend many months at sea, making them difficult to replace. MIT has been thinking about this problem and seems to have found a solution using sound waves themselves as an energy source.
Enter UBL
American researchers named this technique UBL (Underwater Backscatter Localization). Although the name sounds complicated, the concept is relatively simple. Instead of using batteries, it uses the effect of sound waves on piezoelectric mechanisms. Piezoelectricity is the generation of electricity by applying mechanical pressure to certain materials, such as quartz. MIT’s UBL is a prototype underwater tracker that will technically work indefinitely.
This device basically absorbs some of the sound wave energy from the underwater environment into a piezoelectric mechanism and deflects the rest as an acoustic signal. The receiver converts this sequence (the “backscatter” portion) into binary code. The UBL therefore emits a response to acoustic pulses that provide information about water salinity and temperature. It also pinpoints the exact location of marine life and even the impact of climate change on aquatic environments.
echo of the sea
Although this technology has great potential, it faces several challenges. The most important of them is Echo. This is because the acoustic signal not only travels to the receiver, but also travels to the ocean floor and surface, bouncing back and forth. This is not a serious problem in deep water. This is because it is enough to use waves of different frequencies, a technique known as frequency hopping. However, in shallow waters, wave reflections are amplified by bouncing off the seafloor and surface. To solve this, MIT engineers chose to modulate the sound waves by lowering the signal’s frequency or bit rate. With this approach, no new signal is emitted until the previous signal has disappeared.
The only problem with this approach is that it requires high bit rates to monitor moving objects. If the sound waves are too far apart, the object has already changed its position. Finding the right balance point between water depth, sound frequency and motion of the tracked object is the main focus of current research.
As the researchers point out, such developments are very important because the lunar surface is better known than the ocean floor. One reason is the inability to ship unmanned rovers for long periods of time. And speaking of rovers, we recommend this article on underwater robots inspired by sea creatures.
sauce: MIT
