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In the scenario of UAC(Underwater Acoustic Communication) between the USV(Unmanned Surface Vehicle) and underwater node, the affection originated from sea surface random fluctuation to UAC system stability cannot be neglected due to the small size of hull and the shallow draft, especially when USV is sailing near sea surface. The experimental results indicate that the random fluctuation of the sea surface has several influences both on signal propagation and multi-channel structure, and they are difficult to describe quantitatively. Following the research of?marine environment – channel characteristics – underwater acoustic communication’, this paper proposes a shallow sea wave spectrum model(USV_SW) to design UAC system based on measured data including the environment parameters, wind speed, wind direction, and real-time water depth. Moreover, the verification of elevation is presented between the proposed USV_SW model and CORS_GPS(Continuously Operating Reference Stations GPS) data collected on USV. Therefore, we calculated the average acoustic reflection coefficient of random fluctuation interface which is applied for the following simulation analysis of vertical and horizontal channels influenced by interface fluctuation. Simulation results show that the horizontal channel is affected more by random interface fluctuation and its characteristic signal space–time fluctuation is noteworthy in bad sea conditions. The analysis of the random fluctuation interface on the channel structure provides data and theoretical support for the design of the USV underwater acoustic communication scheme. |
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