Cross-ice acoustic communication: Cascade acoustic channel model and experimental results

Cross-ice acoustic information transmission is an effective means of communication in polar sea areas covered by ice. However, the channel is extremely complicated because of the combined influence of water, ice, and air. Based on the normal-mode theory, this paper establishes a cascade acoustic channel (CAC) model for the transmission of under-water acoustic waves across ice layer. The model cancalculate the displacement response of the ice layer's upper surface by separating the upward waves from normal modes in the water and multiplying it by at ransmission coefficient matrix. The relationship between the displacement response of the upper surface of ice layer and the acoustic frequency is calculated by the finite-element method, and the calculation result was consistent with that of the CAC model. To verify the applicability of the model, a cross-ice acoustic communication experiment was conducted in Songhua River in January 2019. Experimental results show the energy of the acoustic signals received by geo-phones is closely related to sound frequency and cross-ice acoustic communication is feasible. The result of present research is important for understanding cross-ice acoustic channel characteristics and developing future cross-ice acoustic communication in polar sea areas.