Abstract: A small aperture acoustic velocity sensor and a method for velocity measurement are disclosed. In one aspect, the disclosed technology uses spatially-shifted sub-arrays for projection and/or hydrophone receipt and cross-correlation of successive pulses to improve correlation and reduce bias. The spatial shift can be created physically by selection of groups of elements or virtually by weighting the contributions of fixed sub-arrays. Spatial modulation can be used to form a projected signal and measured spatial phase of slope across the set of sub-arrays allows correction of both long- and short-term errors. The disclosed technology uses spatial and/or temporal interpolation.

Abstract: A flexible lid seal detector incorporates a compression body having a cavity including a sensor. The detector has a distal end comprising a plurality of concentric compression rings surrounding the cavity. An outer-most ring is defined by outer and inner shaping rims. The distal end includes a recessed lid deflection volume defined by the inner rim and a distal surface of the compression body. The deflection volume may receive a portion of a flexible lid when at least one of the rings applies a compressive force thereto, thereby deforming the lid into the deflection volume. The deflection volume may include a second compression ring and its respective inner and outer shaping rims. A seal detector system may include the detector with a controller configured to receive data from the sensor for a predetermined period of time while the detector applies the compressive force to the lid.

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: An acoustic dual-frequency phased array system with common beam angles is disclosed. In one aspect, the system includes a planar array of transducer elements and a multiplexing circuit for selecting between a first state and a second state during either transmit operation, receive operation or both transmit and receive operation. The multiplexer is configured to connect transducer elements to a plurality of connections different between the first state and second state. The system is configured to transmit and receive beams at a first frequency when the multiplexer is in the first state and transmit and receive beams at a second frequency when the multiplexer is in the second state. The angle of the beams from vertical in the first and second state are substantially similar.

Abstract: A gas mixing device for a NOx detector includes a 3/2 way gas valve having a diaphragm, a first inlet port, a second inlet port, and an exit port. A gas conduit connects the exit port to a gas mixing chamber. A controller controls the diaphragm to alternate between a first position and a second position. The first inlet port may receive a sample gas and the second inlet port may receive ozone gas. In the first position of the diaphragm, a bolus of sample gas enters the conduit, and in the second position of the diaphragm, a bolus of ozone enters the conduit. The alternating boluses of sample gas and ozone mix within the conduit and within the mixing chamber. A NOx detection instrument includes the gas mixing device, an ozone gas source, and an NO2 sensor in fluid communication with the mixing chamber.

Abstract: An underwater active sonar system and method for measuring instrument velocity with respect to a boundary surface is disclosed. The system includes an acoustic transducer configured to transmit and receive a plurality of acoustic beams in different directions. The system also includes a processor configured to detect a boundary surface within each beam; iteratively filter received acoustic signals backscattered from the transmitted beams with an adaptive filter and associated bandwidth that is successively decreased for each iteration; and measure instrument velocity with respect to the boundary surface.

Abstract: A redundant memory for use with an instrument arranged to acquire and store data while underwater. Such an instrument comprises a main housing which contains instrument electronics that acquires and may process data received from one or more sensors, with a primary memory located within the main housing and arranged to store at least some of the acquired and/or processed data, and a secondary memory which stores a copy of the data stored in the primary memory. The instrumentation may be arranged to write data to the primary and secondary memories contemporaneously in either a burst or continuous mode, or with primary memory backed up to secondary memory periodically and/or in response to the occurrence of a triggering event. The instrument may comprise a second housing within which the secondary memory is located. The main and second housings may be contained within a common enclosure.

Abstract: A connector assembly includes a first and a second releasable and mateable connector. Each connector includes a front assembly composed of a manifold and a plurality of optical stems. Each manifold includes a plurality of inserts and a plurality of spherical seal assemblies. Each seal assembly is composed of a spherical ball, a ball dowel pin, and a ball actuator pin having a cam. Each spherical ball is configured to rotate about an axis defined by the two pins when the actuator pin cam traverses a groove fabricated in one of a plurality of guide rails disposed in the first connector. When the plurality of seal assemblies are in an open configuration, the optical stems of the first connector may slide through the inserts of the first connector, through the seals, and mate with the optical stems of the second connector within the inserts of the second connector.

Abstract: An acoustic transducer and method of generating acoustic transmit and receive beams is disclosed. The system includes a plurality of transducer elements arranged to form an array, where the elements are electrically connected into groups which operate at the same electrical phase, where the phases of adjacent groups of elements differ by between about 50 and 70 degrees and a beamforming circuit where the transmit and receive signals are operated with appropriate phase shifts to maintain the between about 50 and 70 degrees phase difference between adjacent groups. The resulting transducer generates transmit and receive beams that are nominally inclined less than about 30 degrees from a planar normal axis of the array.

Abstract: A connector comprising a contact, a plunger, and a spring activated seal is provided. The contact is positioned within the housing and configured to transmit at least one of an electrical signal and an optical signal between the connector and a secondary device. The plunger is positioned within the housing and in communication with the contact. The spring activated seal comprises a flexible portion and a spring configured to urge the flexible portion to contact the housing and at least one of the plunger and a contact of the secondary device to form a fluid tight seal therebetween.

Abstract: A connector comprising a contact, a plunger, and a spring activated seal is provided. The contact is positioned within the housing and configured to transmit at least one of an electrical signal and an optical signal between the connector and a secondary device. The plunger is positioned within the housing and in communication with the contact. The spring activated seal comprises a flexible portion and a spring configured to urge the flexible portion to contact the housing and at least one of the plunger and a contact of the secondary device to form a fluid tight seal therebetween.

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 near-field hydrophone is disclosed. The near-field hydrophone includes a housing, a piezoelectric element configured to produce an analog signal in response to an acoustic signal generated by the release of compressed air into water, an analog circuit coupled to the piezoelectric element, wherein the analog circuit is configured to receive the analog signal and to produce a conditioned analog signal, an analog-to-digital converter configured to receive the conditioned analog signal and to produce a digitized form of the conditioned analog signal, and a processor coupled to a memory circuit and to the analog-to-digital converter, wherein the processor is configured to control the operation of the analog-to-digital converter and to provide a digitized serial communication output corresponding to the digitized form of the conditioned analog signal. The piezoelectric element, the analog circuit, the analog-to-digital converter, the processor, and the memory circuit are located within the housing.

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 small aperture acoustic velocity sensor and a method for velocity measurement are disclosed. In one aspect, the disclosed technology uses spatially-shifted sub-arrays for projection and/or hydrophone receipt and cross-correlation of successive pulses to improve correlation and reduce bias. The spatial shift can be created physically by selection of groups of elements or virtually by weighting the contributions of fixed sub-arrays. Spatial modulation can be used to form a projected signal and measured spatial phase of slope across the set of sub-arrays allows correction of both long- and short-term errors. The disclosed technology uses spatial and/or temporal interpolation.

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 diffusion system to improve the efficiency, accuracy, and consistency of testing the release rate of an active ingredient in semisolid form through a membrane in between a dosage lid and a cell cap mounted on a cell in which a mixer is placed to mix the receptor medium in the cell as the semisolid diffuses through the membrane. The cell can be placed in a heating system to heat the samples. The cell has a sampling arm through which samples of the receptor medium can be extracted without opening the cell cap and dosage lid. The mixer may be cylindrical and may occupy a large surface area of the cell. The mixer may have grooves and other irregularities to increase turbulence while mixing. The system can be automated using an automated sampling and collection station.