Development of high-data-rate underwater acoustic communication for ultra-deep-sea exploration systems

Exploring ultra-deep seafloor areas at depths exceeding 6000 m, such as plate boundaries where large earthquakes originate, is of great scientific and societal importance. However, such surveys are constrained by limited opportunities and a lack of environmental information. To conduct surveys more efficiently under these conditions, real-time transmission of data from the seafloor to the surface vessel is highly desirable. This study focuses on developing and evaluating an underwater acoustic communication system capable of transmitting camera images and various sensor data from ultra-deep environments to the surface in near real time, with an update interval of less than a few seconds. We analyze data obtained from field experiments using a manned submersible and a free-fall lander system and investigate signal processing algorithms designed to adapt to the dynamic characteristics of underwater acoustic channels. The practical implementation and deployment of the developed system are also presented. [Work supported by JSPS KAKENHI (Grant No. JP24K17462).]