Various implementations described herein are directed to a trolling device having a motor with a propeller coupled to the motor and a shaft configured to couple or mount the motor to a watercraft. The trolling device may include a housing encapsulating the motor and the housing may include a nosecone. A sonar transducer assembly may be incorporated within the housing or nosecone including a phased array configured to transmit sonar beams into an underwater environment.

Aquatic vehicles may use electric motors for propulsion, such as brushless motors. As an example, a speed of these motors can be controlled using a pulse-width-modulated (PWM) electrical signal that varies the motor speed by varying pulse parameters within the PWM signal. PMW modulation can cause the motor to emit significant acoustic noise into the environment. In a fluid medium, such as aquatic environment, such noise can be detected with hydrophones or other acoustic sensors. The subject matter described herein can include modulating a signal provided to a motor to provide a communication signal to be mechanically (e.g., acoustically) emitted by the motor in a fluid medium, such as an underwater medium. In this manner, the motor can function both as a source of propulsion, and as an electroacoustic transducer (e.g., a transmitter).

The present disclosure relates to a Sonar device (1) for detection of underwater objects. The sonar device (1) comprises a body element (2) comprising a piezo electric element (3). The sonar device further comprises a holder (4) adapted to hold the piezo electric element (3). The holder (4) is arranged to centre the piezo electric element (3) within said body element (2). The holder (4) is arranged such that the piezo electric element (3) is held firmly in place and also provide for that detection can be made omni-directionally. A method for manufacturing a holder (4) and a sonar device (1) is also disclosed.

The present disclosure relates to a sonar device (1) for detection of underwater objects. The sonar device comprises a body element (2) having a cavity. A piezo electric element (3) is comprised within the cavity. A resin filling (6) of the cavity protects the piezo electric element (3) from water at underwater operation. The sonar device further comprises a holder (4) adapted to hold the piezo electric element (3). The holder (4) is arranged to centre and hold the piezo electric element (3) within said body element (2). The holder (4) comprises in its structure a plurality of damping structures (5). A method of manufacturing holder and a sonar device is also disclosed.

Hybrid transducer apparatus which is capable of simultaneously or sequentially forming multiple acoustic beams. In one implementation, the hybrid transducer apparatus consists of a relatively thin piezoceramic disk portion having an aspect ratio less than unity as well as a plurality of diced piezoelectric elements with each of these elements having an aspect ratio greater than unity. The resultant hybrid transducer apparatus reduces the multiple spurious frequency responses seen in prior art implementations and thus can be efficiently treated as a piezoelement having a single degree of freedom along its thickness direction. The hybrid transducer apparatus may also be suitable for use in high voltage and/or high power applications via the inclusion of, for example, a heat conductive epoxy that encapsulates the diced piezoelectric elements.

A device for reducing underwater sound has a holding device and a hydrosound damper with noise reducing elements. The device has a transport housing for transporting the hydrosound damper, a first end of the underwater sound damper being fixed to the transport housing and the transport housing being connected to a holding device via a support device has a cable winch with a support cable arranged on the transport housing and has a motor-driven drum, wherein using the support device, the transport housing is lowered from the holding device to the sea floor.

Disclosed is a waterproof sound-transmitting sheet, which includes a waterproof layer of a nonporous material and a support layer of a porous material, and maintains waterproof performance and sound transmission performance at a water pressure of about 10 atm. The disclosed waterproof sound-transmitting sheet includes a waterproof layer formed of a film shape of a nonporous material, a first adhesive layer having one surface adhered to one surface of the waterproof layer, and a support layer formed of a film shape of a porous material, and having one surface adhered to the other surface of the adhesive layer; and the support layer can be composed of metal mesh or nonwoven fabric.

A sonar transducer assembly is provided including a transducer configured to transmit one or more sonar beams into an underwater environment, a housing that holds the transducer, at least one electrical cable that enables electrical signals to be transmitted between the transducer and a computing device, and a conductive enclosure disposed around at least a portion of the transducer and electrically connected to a ground line of the electrical cable to create a shielded volume. The conductive enclosure reduces an electromagnetic field within the shielded volume.

A device for use in a medium comprising a medium vibro-acoustic impedance. The device includes an elastic material including a plurality of unit cells. The plurality of unit cells includes a first unit cell. The first unit cell includes a first unit-cell joint comprising a first unit-cell joint wall defining a first joint central void, a first unit-cell joint inclusion located in the first joint central void, and at least two first unit-cell arms connected to and extending away from the first unit-cell joint. The elastic material includes an elastic-material vibro-acoustic impedance. The elastic-material vibro-acoustic impedance and the medium vibro-acoustic impedance are sufficiently vibro-acoustically impedance-matched to couple time-varying, propagating vibro-acoustic fields between said elastic material and the medium.

A system for producing sound waves in a medium, the system comprising: at least two first free-flooded ring transducers centered about a first axis, the first free-flooded ring transducers being substantially cylindrical and having an axial gap of height g therebetween such that they form a first column; and at least one cylindrical body centered about the first axis nested in the first column, such that the cylindrical body is aligned with the axial gap. The cylindrical body may be a tweeter free-flooded ring transducer. This provides for improved wideband performance in a free flooded ring array.