Characterization of Low-Cost Transducers for Underwater Communications

Acoustic transducers for underwater communications are one of the most expensive components of underwater acoustic modems and their applications. Their production involves the use of expensive materials, such as piezoelectric ceramic rings, tubes, or spheres, and molding materials, which are difficult to operate due to their sensitivity to humidity, temperature, and vibrations. Moreover, it is not easy to automate this process, which mostly results in a specialized operator spending a few hours to manufacture and calibrate each handmade transducer, and in a final price that is often more than 2000 USD per unit. Therefore, such transducers are used only in high-power underwater acoustic modems for defense and Oil&Gas applications, making them not suitable for low-cost deployment such as communication systems for divers, Autonomous Underwater Vehicle (AUV) swarms or sensors networks for coastal monitoring. To enable such applications, different alternatives have been proposed, from using other components, such as fish-finders and hydrophones with low transmitting voltage response, to homemade low-cost transducers. In this paper, we discuss the advantages and disadvantages of both solutions, presenting our experience and the lessons we learned while producing our lowcost transducer, which is a key element for underwater communication and its application in coastal monitoring deployments.