Sonar device sees through bubble clouds

Conventional sonar uses the differences between emitted sound pulses and their echoes to detect and identify targets. These include submerged structures such as reefs and wrecks, as well as objects including submarines and fish shoals.

However, standard sonar does not cope well with bubble clouds resulting from breaking waves or other causes, which scatter sound and clutter the sonar image.

Now, Prof Timothy Leighton of Southampton University’s Institute of Sound and Vibration Research (ISVR) has developed a new twin inverted pulse sonar (TWIPS) system that can do just that.

Leighton’s team first showed theoretically that the TWIPS system could enhance the scatter from a target while simultaneously suppressing the clutter from bubbles. Then, the researchers set out to see whether the TWIPS would work in practice, distinguishing echoes from bubble clouds and objects that would otherwise remain hidden.

Using a large testing tank, they showed experimentally that the TWIPS system outperformed standard sonar at detecting a small steel disc under bubbly conditions resembling those found under oceanic breaking waves.