Abstract: Disclosed is a diver's voice communication system which utilizes AI speech recognition, speech-to-text conversion with the ability to adapt to diver speech distortion resulting from hyperbaric helium-oxygen conditions and text transmission using underwater acoustic digital communication. Additionally, the communication system provides the ability to use speech commands in a digital form to control underwater autonomous devices. Further, the digital communication system provides the ability to track and communicate with a large number of divers or with select divers from a large group.

Abstract: Disclosed is a diver's voice communication system which utilizes AI speech recognition, speech-to-text conversion with the ability to adapt to diver speech distortion resulting from hyperbaric helium-oxygen conditions and text transmission using underwater acoustic digital communication. Additionally, the communication system provides the ability to use speech commands in a digital form to control underwater autonomous devices. Further, the digital communication system provides the ability to track and communicate with a large number of divers or with select divers from a large group.

Abstract: A sound source for acoustic communication, navigation, and networking of an underwater glider may include a cylindrical body, a rigid front section disposed anteriorly to the cylindrical body, a plurality of metal rods, a resonant pipe surrounding the rods, and a rod-mounted piezo-ceramic transducer disposed between the body and the front section. Each rod may be attached at a first end to an anterior portion of the body and at a second end to a posterior portion of the front section. The pipe may be disposed between the body and the front section. The transducer may be disposed within the pipe. A posterior end of the pipe may be separated from the anterior portion of the body by a first orifice, and an anterior end of the pipe may be separated from the posterior portion of the front section by a second orifice.

Abstract: A sound source for acoustic communication, navigation, and networking of an underwater glider may include a cylindrical body, a rigid front section disposed anteriorly to the cylindrical body, a plurality of metal rods, a resonant pipe surrounding the rods, and a rod-mounted piezo-ceramic transducer disposed between the body and the front section. Each rod may be attached at a first end to an anterior portion of the body and at a second end to a posterior portion of the front section. The pipe may be disposed between the body and the front section. The transducer may be disposed within the pipe. A posterior end of the pipe may be separated from the anterior portion of the body by a first orifice, and an anterior end of the pipe may be separated from the posterior portion of the front section by a second orifice.

Abstract: A submersible sound system may include a housing, an end piece, an elastic membrane, an end cap affixed to the elastic membrane, and a subwoofer speaker system disposed within the housing and supported by a speaker support. A bubble sound source may be defined by the speaker support, the speaker diaphragm, an anterior end of the housing, the elastic membrane, and the end cap. The housing, end piece, and a posterior surface of the speaker support may form a sealed enclosure. The sound system may include a tuning pipe disposed between the sealed enclosure and the bubble sound source. A Helmholtz resonator may be disposed anteriorly of the speaker system. Multiple sound system may be assembled to form a cluster. The cluster may be defined by the vertices of regular polyhedron. The sound systems may be controlled to maintain the speaker systems within acceptable thermal limits.

Abstract: A submersible sound system may include a housing, an end piece, an elastic membrane, an end cap affixed to the elastic membrane, and a subwoofer speaker system disposed within the housing and supported by a speaker support. A bubble sound source may be defined by the speaker support, the speaker diaphragm, an anterior end of the housing, the elastic membrane, and the end cap. The housing, end piece, and a posterior surface of the speaker support may form a sealed enclosure. The sound system may include a tuning pipe disposed between the sealed enclosure and the bubble sound source. A Helmholtz resonator may be disposed anteriorly of the speaker system. Multiple sound system may be assembled to form a cluster. The cluster may be defined by the vertices of regular polyhedron. The sound systems may be controlled to maintain the speaker systems within acceptable thermal limits.

Abstract: An underwater sound source includes a cylindrical body having a front body portion, a rear body portion, a cylindrical piezo-ceramic ring transducer disposed therebetween, a flexible sleeve configured to cover an outer surface of the cylindrical piezo ceramic ring transducer, and a resonant pipe mounted to the cylindrical body and surrounding the cylindrical piezo-ceramic ring transducer. The resonant pipe is disposed around the cylindrical piezo-ceramic ring transducer, forming a gap between an inner surface of the resonant pipe and the outer surface of the cylindrical piezo-ceramic ring transducer.

Abstract: A submersible sound system may include a housing, an end piece, an elastic membrane, an end cap affixed to the elastic membrane, and a subwoofer speaker system disposed within the housing and supported by a speaker support. A bubble sound source may be defined by the speaker support, the speaker diaphragm, an anterior end of the housing, the elastic membrane, and the end cap. The housing, end piece, and a posterior surface of the speaker support may form a sealed enclosure. The sound system may include a tuning pipe disposed between the sealed enclosure and the bubble sound source. A Helmholtz resonator may be disposed anteriorly of the speaker system. Multiple sound system may be assembled to form a cluster. The cluster may be defined by the vertices of regular polyhedron. The sound systems may be controlled to maintain the speaker systems within acceptable thermal limits.

Abstract: A submersible sound system may include a housing, an end piece, an elastic membrane, an end cap affixed to the elastic membrane, and a subwoofer speaker system disposed within the housing and supported by a speaker support. A bubble sound source may be defined by the speaker support, the speaker diaphragm, an anterior end of the housing, the elastic membrane, and the end cap. The housing, end piece, and a posterior surface of the speaker support may form a sealed enclosure. The sound system may include a tuning pipe disposed between the sealed enclosure and the bubble sound source. A Helmholtz resonator may be disposed anteriorly of the speaker system. Multiple sound system may be assembled to form a cluster. The cluster may be defined by the vertices of regular polyhedron. The sound systems may be controlled to maintain the speaker systems within acceptable thermal limits.

Abstract: A submersible sound system may include a housing, an end piece, an elastic membrane, an end cap affixed to the elastic membrane, and a subwoofer speaker system disposed within the housing and supported by a speaker support. A bubble sound source may be defined by the speaker support, the speaker diaphragm, an anterior end of the housing, the elastic membrane, and the end cap. The housing, end piece, and a posterior surface of the speaker support may form a sealed enclosure. The sound system may include a tuning pipe disposed between the sealed enclosure and the bubble sound source. A Helmholtz resonator may be disposed anteriorly of the speaker system. Multiple sound system may be assembled to form a cluster. The cluster may be defined by the vertices of regular polyhedron. The sound systems may be controlled to maintain the speaker systems within acceptable thermal limits.

Abstract: A submersible sound system may include a housing, an end piece, an elastic membrane, an end cap affixed to the elastic membrane, and a subwoofer speaker system disposed within the housing and supported by a speaker support. A bubble sound source may be defined by the speaker support, the speaker diaphragm, an anterior end of the housing, the elastic membrane, and the end cap. The housing, end piece, and a posterior surface of the speaker support may form a sealed enclosure. The sound system may include a tuning pipe disposed between the sealed enclosure and the bubble sound source. A Helmholtz resonator may be disposed anteriorly of the speaker system. Multiple sound system may be assembled to form a cluster. The cluster may be defined by the vertices of regular polyhedron. The sound systems may be controlled to maintain the speaker systems within acceptable thermal limits.

Abstract: A low frequency underwater sound source for use in an autonomous underwater vehicle includes a cylindrical body having a front portion, a rear portion, a cylindrical piezo-ceramic ring transducer disposed therebetween, and a resonant pipe surrounding the transducer. A gap is formed between an inner surface of the pipe and an outer surface of the transducer. Alternatively, the sound source includes a cylindrical body, a front fairing disposed forward of the cylindrical body, a plurality of metal rods connecting the front of the cylindrical body and the rear of the fairing, a spherical piezo-ceramic transducer disposed between the cylindrical body and the fairing, and a resonant pipe mounted at the front end of the cylindrical body. The spherical transducer is disposed within a cavity within the resonant pipe. A cylindrical orifice is formed between the front end of the resonant pipe and the rear of the fairing.

Abstract: A submersible sound system may include a housing, an end piece, an elastic membrane, an end cap affixed to the elastic membrane, and a subwoofer speaker system disposed within the housing and supported by a speaker support. A bubble sound source may be defined by the speaker support, the speaker diaphragm, an anterior end of the housing, the elastic membrane, and the end cap. The housing, end piece, and a posterior surface of the speaker support may form a sealed enclosure. The sound system may include a tuning pipe disposed between the sealed enclosure and the bubble sound source. A Helmholtz resonator may be disposed anteriorly of the speaker system. Multiple sound system may be assembled to form a cluster. The cluster may be defined by the vertices of regular polyhedron. The sound systems may be controlled to maintain the speaker systems within acceptable thermal limits.

Abstract: In one aspect, an acoustic full-duplex communication system includes a transmitter array having at least two transmitters. The transmitters are positioned along an axis of maximum transmission and are separated by about half of a wavelength of a transmission frequency band. The transmitters transmit waveforms of opposing polarity that mutually interfere in a plane orthogonal to the transmission axis. The system includes a receiver array having at least one receiver in the orthogonal plane. In a second aspect, an underwater acoustic full-duplex communication system includes a transmitter and two receivers. The receivers are symmetrically positioned about an axis, separated by about half of a wavelength of a transmission frequency band, and equidistant from the transmitter. The receivers are connected in opposing polarity. Either aspect may include an adaptive filter to improve cancellation of transmitter originated near field transmissions received by the one or more receivers.

Abstract: A hybrid energy harvesting system for powering underwater vehicles having at least one thermal engine, at least one of a solar or a wave energy harvester, and a battery which stores electric energy produced by the harvesters. The energy harvesters keep the battery charged and thereby expand an underwater vehicle's operational areas to high latitudes and shallow water. Multiple thermal engines employing different phase-change materials can be used to expand the vehicle's working temperature range and thus allow it to operate over a larger area. An electric motor powered by the battery and a pump driven by the motor can be used to pump hydraulic fluid between the accumulators and external bladders of the thermal engines to cause the vehicle to descend and ascend when the thermal gradient to which the vehicle is subjected is insufficient.

Abstract: An underwater sound source includes an acoustical driver, a controller of the acoustical driver, and a resonant tube acoustically coupled to the acoustical driver. The resonant tube has a pair of slotted portions, in which each slotted portion is disposed along the length of the resonant tube at a location corresponding to a node of a harmonic of the resonant tube. The sound system is configured to emit an output signal within a bandwidth defined by a dual resonance characteristic of the resonator tube. The sound source may also include a pair of coaxial tubular sleeves disposed around the resonant tube, each sleeve configured to slidably cover one of the slotted portions, and tune the resonance frequency of the tube over a wide range. At a high frequency end, when slots are uncovered, the frequency response of the resonant tube obtains a dual-resonant form.

Abstract: A sound source including a first gas filled underwater resonator, a second gas filled underwater resonator connected to the first resonator, where the second resonator comprises a Helmholtz resonator, and at least one excitation member configured to excite the first resonator and the second resonator is disclosed. The first resonator is permanently tuned to produce a first resonant frequency upon excitation by the at least one excitation member and the second resonator is permanently tuned to produce a second resonant frequency upon excitation by the at least one excitation member. The first resonant frequency is different from the second resonant frequency.

Abstract: A variable inductor includes a three-limbed core first section having an inductor winding wound about a medial limb. An air gap is disposed in the medial limb. The inductor includes a second section having a control limb in which a first end of the control limb is connected to a first outer limb of the three-limbed core, and a second end of the control limb is connected to a second outer limb of the three-limbed core. A control winding is wound about the control limb. The inductor may be used in a control circuit to control a power signal driving a transducer. The inductor may be controlled by a signal derived from a comparison of a voltage phase of a power signal to the transducer and a phase of the current traversing the transducer. A system may include the control circuit, including the variable inductor, and the transducer.

Abstract: An underwater sound source includes an acoustical driver, a controller of the acoustical driver, and a resonant tube acoustically coupled to the acoustical driver. The resonant tube has a pair of slotted portions, in which each slotted portion is disposed along the length of the resonant tube at a location corresponding to a node of a harmonic of the resonant tube. The sound system is configured to emit an output signal within a bandwidth defined by a dual resonance characteristic of the resonator tube. The sound source may also include a pair of coaxial tubular sleeves disposed around the resonant tube, each sleeve configured to slidably cover one of the slotted portions, and tune the resonance frequency of the tube over a wide range. At a high frequency end, when slots are uncovered, the frequency response of the resonant tube obtains a dual-resonant form.

Abstract: In one aspect, an acoustic full-duplex communication system includes a transmitter array having at least two transmitters. The transmitters are positioned along an axis of maximum transmission and are separated by about half of a wavelength of a transmission frequency band. The transmitters transmit waveforms of opposing polarity that mutually interfere in a plane orthogonal to the transmission axis. The system includes a receiver array having at least one receiver in the orthogonal plane. In a second aspect, an underwater acoustic full-duplex communication system includes a transmitter and two receivers. The receivers are symmetrically positioned about an axis, separated by about half of a wavelength of a transmission frequency band, and equidistant from the transmitter. The receivers are connected in opposing polarity. Either aspect may include an adaptive filter to improve cancellation of transmitter originated near field transmissions received by the one or more receivers.