Two-Way Communication System between Surface Controller and Diver via Signal Buoy for Enhanced Underwater Safety

Abstract

This paper presents the concept, design, preliminary and experimental results of a prototype two-way communication system between a surface operator and a diver through a floating relay buoy. The system aims to provide real-time text and video transmission to enhance safety during underwater operations. The prototype consists of three main components: (1) Surface Control Unit, (2) Floating Relay Buoy, and (3) Diver Unit. Communication is established through standard IEEE 802.11 2.4 GHz/5 GHz wireless links combined with a waterproof Ethernet tether, utilizing the ZMQ (ZeroMQ) protocol in a publish – subscribe architecture for efficient data exchange. A field-like test was conducted using a TP-Link EAP225 device configured as a Wireless Access Point / Bridge to connect the surface control system with the diver unit through the Ethernet tether. The diver unit employed a Raspberry Pi 4 and a USB camera for processing and transmitting live video. The results show that the system successfully transmitted text messages from the surface to the diver and streamed live video from the diver to the surface in real time, with an average latency below 300 ms and no packet loss over a continuous 10-minute test period. Limitations include wireless range constraints, tether-induced mobility restrictions, and the absence of testing in deep or high-current underwater environments, as well as the lack of encryption and QoS management for multi-user applications. Experimental outcomes confirm that the proposed prototype operates effectively in field conditions and demonstrates the feasibility of a Hybrid LAN/WLAN underwater communication system for future diving operations.