Authorship：Last author   Language：English   Publishing type：Research paper (international conference proceedings)

Diving operations are crucial yet hazardous, demanding efficient communication between divers and surface supervisors. This paper proposes a real-time underwater video conferencing system utilizing commercial smartphones and underwater radio frequency communication based on the PLC standard (IEEE 1901c). We conducted a verification experiment in a large freshwater tank to verify its effectiveness for operational support. The study analyzed the time lag between surface instructions and diver actions using defined behavioral metrics. Results indicated that divers smoothly transitioned to assigned tasks within 10 seconds of receiving visual commands, demonstrating communication stability comparable to terrestrial environments. These findings confirm the system's potential for enhancing safety and efficiency in remote underwater assistance, while highlighting the need for future validation in seawater and low-visibility conditions.

DOI： 10.5954/icarob.2026.os5-10

Kyutacar

CiNii Research

Authorship：Last author   Language：English   Publishing type：Research paper (international conference proceedings)

Signal attenuation and multipath effects remain key barriers to underwater communication. A novel RF-enabled strategy supports Operator–Diver communication over Zoom/OBS but lacks Diver–Diver communication and diverinitiated UUV control. This limitation is due to restricted touchscreen access in a sealed housing. We present a multimodal RF-enabled iOS framework that supports three modes: Operator–Diver communication, Diver–Diver communication, and Diver–UUV control. System concept and RF pathway are described, demonstrating how the proposed architecture overcomes the current constraints.

DOI： 10.5954/icarob.2026.os5-14

Kyutacar

CiNii Research

Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)

The manuscript introduces a radio wave-based wireless communication system tailored for Autonomous Underwater Vehicles (AUVs), optimized for underwater deployment. Initial experiments to ascertain the fundamental properties of a loop antenna were conducted in a small-scale water tank, followed by comprehensive communication and video transmission trials in a larger tank with an AUV. A specialized waterproof enclosure was developed to house a waterproof antenna, a Vector Network Analyzer (VNA), and a communication board. This setup facilitated the evaluation of the loop antenna’s radio propagation attributes and the identification of frequencies conducive to underwater communication. Designed with practical deployment in mind, the system incorporates a 2-meter loop antenna for signal transmission and a 0.5m by 0.8m rectangular loop antenna integrated into the AUV for signal reception. Utilizing a wavelet Orthogonal Frequency Division Multiplexing (OFDM) communication board and tuning to lower frequencies, the system successfully established User Datagram Protocol (UDP) and Transfer Control Protocol (TCP) communications within a few meter radius from the transmitting antenna, achieving data transfer rates up to 6.8 Mbps.

DOI： 10.1109/ACCESS.2024.3457508

Kyutacar

Authorship：Last author   Language：English   Publishing type：Research paper (international conference proceedings)

As the marine business expands, there is a growing demand for real-time capturing of autonomous underwater vehicles (AUVs) status using radio frequency communications. On the other hand, electromagnetic noise emitted by AUVs can interfere with communications.To investigate the impact of electromagnetic noise in undersea Wavelet-OFDM communication, the author constructed an experimental setup that simulates the radio wave transmission characteristics of underwater antennas without the experimental environment in the sea and introduced external noise to assess communication speed. The authors compared the noise power induced in the receiver to the communication speed using the proposed evaluation setup.
The results shows that when the distance between the loop antennas was 1 m, communication was disabled by applying a -90 dBm disturbance. Additionally, the author proposed a method to estimate communication speed using transmission characteristics and measured electromagnetic noise. The communication speeds calculated using the proposed method agreed with the measured results with a maximum error of 1.65 Mbps. Improving accuracy remains a challenge for future research.

DOI： 10.34385/proc.82.thuam1a.4

Kyutacar

CiNii Research

Authorship：Last author   Language：English   Publishing type：Research paper (international conference proceedings)

The authors' research group is engaged in research and development of undersea radio communication technology. To improve communication efficiency, antenna characteristic and communication system are being developed through actual measurement. However, it is not easy to conduct large-scale measurement because of the time and cost required for preparation. Therefore, an undersea communication emulator that simulates undersea radio wave attenuation is being built to simplify large-scale experiment. In this paper, an undersea communication emulator of the transmission characteristic obtained by actual measurement is fabricated, and comparison of transmission characteristic and communication performance are shown through communication experiment. As a result of evaluating the communication characteristics of the fabricated emulator, it was confirmed that the transmission characteristic was expressed with a difference of less than 1 dB in a bandwidth of approximately 85 % of the carrier frequency, and that the transmission rate could be simulated with an accuracy of less than 1 Mbps.

DOI： 10.34385/proc.82.thuam1a.3

Kyutacar

CiNii Research

Language：Japanese

Language：Japanese

Language：Japanese   Presentation type：Invited lecture  

Language：Japanese   Presentation type：Special lecture  

Language：Japanese   Presentation type：Special lecture  

Language：Japanese   Presentation type：Special lecture  

Language：Japanese   Presentation type：Special lecture