Affordable underwater acoustic modems and their application in everyday life: a complete overview

In the past, underwater acoustic modems were mainly used in Oil & Gas and military scenarios, that need long range transmissions with high power emitters often deployed in deep water. For this reason, the development of low-cost acoustic modems was limited to academic activities and experimentation. Recently, the new developments of low-cost unmanned vehicles suitable for shallow-water shore and coastal missions, and the need for sensors networks for measuring water quality and studying the effect of climate change in littoral areas, highlighted the need for low-cost and low-power acoustic modems. These communication systems can enable a wide set of applications, often based on low-cost underwater and surface unmanned vehicle swarm formations, where an acoustic link between the vessels is required to coordinate the mission and maintain the formation. In fact, these low-cost modems can be used for small-scale applications thanks to their low price at the cost of a low transmission range and throughput, when compared with the performance achievable with legacy acoustic modems. In this paper, we review the recent developments of low-cost and low-power acoustic communication, identifying advantages and limitations of these devices, and describe potential new applications that can be enabled by these systems.