In-situ performance prediction of a coherent acoustic modem

A channel sounding and communications experiment was performed in the Oslofjord in April/May 2019, where 8 bottom units were deployed in a network configuration. Five units were equipped with a software-defined acoustic modem operating in the 4–8 kHz band, programmed to transmit probe signals and communication packets. All transmitted signals were recorded by all units over 35 unique horizontal links and 5 vertical links. Measured power delay profiles are used to predict receiver output SNR, examining the effect of ambient noise, reverberation of previously transmitted packets, and the packet's own reverberation. It is shown that modem performance is limited by the own reverberation, and that the mean prediction error is below 3 dB when this reverberation is taken into account.