Underwater Acoustic Communication Channel Characterization at Low Frequencies in Shallow Water

The channel characteristics for sound propagating at 1100 Hz off Nova Scotia, Canada in winter conditions were measured at a shallow water station over Sable Bank.Experimental and model results for propagation loss and time spreading are compared at source-receiver separations out to 180 kilometers.Relatively little time spreading was observed which is consistent with propagation dominated by a small number of modes.The low propagation losses observed are attributed to low bottom losses.The data were gathered using mobile platforms.The observed frequency spreading (typically 0.25 Hz) is attributed to platform motion excited by motion of the sea surface.The applicable propagation parameters are used to predict the channel capacity of a Differential Quadrature Phase Shift Keying communication system operating in the same environment and using a vertical receiving array to provide modal decomposition (mode filtering).The issue of providing suf cient transmitter power to meet a speci c error rate speci cation is also addressed.