Link Strength for Unmanned Surface Vehicle's Underwater Acoustic Communication

摘要

Due to the constant improvement of point-to-point underwater acoustic communication technology, underwater acoustic communication networks in oceans will become a reality. In recent years, unmanned vehicles such as AUVs and Gliders, have gradually matured and been perfected, and can be used as a novel kind of underwater acoustic node. In this paper, a novel Unmanned Surface Vehicle (USV) integrated underwater acoustic modem is introduced. Due to the complexity of underwater acoustic channels, the harsh marine environment and aspects of the USV's manipulation, underwater acoustic communication that links modeling and estimation is essential for USV communications and applications. Firstly, the underwater acoustic communication distance, USV running condition and the Marine environment are considered as the main factors affecting a USV's acoustic communication. Corresponding to the above factors, communication energy loss model, USV motion model and marine environmental impact model are established respectively. Secondly, analyzing the interactions among the three models, a USV underwater acoustic communication link strength model is constructed. Lastly, USV underwater acoustic communication is tested on our USV carrying an EvoLogics acoustic modem, icListen self-contained hydrophone, CTD, electronic compass and GPS at Jihongtan reservoir in Qingdao in July 2015. In the experiments, the bank station transmitting modem is fixed at a depth of 2m, and the receiving modem is integrated in our USV at a depth of 3m. Underwater acoustic communications for fixed points at 50m intervals, and for mobile reception, are executed in a 1000m line respectively. Verification and inspection of the proposed communication link strength model are carried out by analyzing the signal strength along with the communication distance, signal frequency, roll Angle, pitch Angle, velocity of USV, velocity of sound and noise, From the above experiments, it is concluded that the USV as a mobile relay node is very effective, and its underwater acoustic communication link strength model can justifiably be adopted to describe its communication ability. This will provide a reference for underwater acoustic applications of USV in the future.