Abstract: An ultrasonic transducer with housing contains a transducer assembly, an outer housing surface being fixed against a barrier surface for transferring ultrasonic waves to and from a barrier. The housing has an inner surface with plateau. A cap closes the housing and the transducer assembly has a piezoelectric transducer with a pressure surface around its outer perimeter and an opposite vibration surface engaging the plateau. A ring engages the pressure surface for biasing the vibration surface against the plateau. A holder engages the cap, transducer and ring for positioning and a plurality of springs are spaced around the transducer perimeter and between the cap and ring for biasing the vibration surface toward or against the raised plateau. A viscous couplant is between the vibration surface and plateau for enhancing transmission of the ultrasonic waves.

Abstract: An apparatus and method for transmitting data and power through a metal barrier using ultrasonic waves, having ultrasonic transmission channels through the barrier formed by coupling ultrasonic transducers on opposite sides of the barrier. A power transmitter sends power over a channel and forward and reverse data transmitters send forward and reverse data signals by orthogonal frequency-division multiplexing OFDM over a separate channel. The data signals are made up of plural sub-carriers at plural different sub-carrier frequencies with none of the sub-carriers of the forward transmission signal being at a power harmonic frequency.

Abstract: Method and apparatus for rotational alignment and attachment of ultrasonic transducers to a barrier with one submerged surface uses a temporary transducer assembly to position mounting rings on opposite surfaces of the barrier. Plural permanent transducers are then mounted to each mounting ring and are aligned with each other across the barrier by virtue of the alignment of their mounting rings. The submerged mounting ring is used like a cylinder in combination with a mounting plate for the transducers on the submerged side of the barrier or each submerged side transducer has a suction cup fitting for use to exclude water from between each transducer and the submerged barrier surface to facilitate bonding of the submerged side transducers to the barrier.