Abstract: An ultrasonic diagnostic apparatus characterized by comprising, a probe which has a transducer and which transmits and receives ultrasonic waves, an ultrasonic diagnostic apparatus main body; and a cable through which signals are transmitted and received between the ultrasonic diagnostic apparatus main body and the probe, wherein the probe includes a transmission signal generator that generates an ultrasonic transmission signal, a transmission circuit that amplifies the generated transmission signal, and a transmission phasing circuit that adjusts the timing of the transmission signal.

Abstract: A broadband weak-motion seismometer includes: a frame, a mass, a suspension means for movably connecting the mass to the frame, a sensing transducer for measuring displacement of the mass with respect to the frame and for generating a sensing transducer output signal, which is a function of the measured displacement, a forcing transducer for applying a feedback force in a predetermined direction to the mass, and a control circuit. The control circuit receives the sensing transducer output signal and generates a forcing transducer input signal that includes a self-noise component. The forcing transducer input signal is processed by the forcing transducer to apply the feedback force to maintain the mass at rest with respect to the frame. The feedback force is sufficient to counterbalance a constant acceleration of the frame of at least 0.2 m/s2 in the predetermined direction of the feedback force.

Abstract: A method for electromagnetic surveying subsurface formations includes inducing an electromagnetic field in the subsurface formations by passing electric current through a transmitter. Response of the subsurface formations to the induced electromagnetic field is detected at a first plurality of spaced apart positions disposed longitudinally within a bipole length of the transmitter. A direct induction response is removed from the detected response.

Abstract: A solid state seismic trigger switch for contact closure. Capable of being utilized by all seismic recording devices. Consisting of two wires, an air filled copper tube and an outer protective hull. One of the wires goes through the center of the air filled copper tube. Along this wire, near the end, a variable mass of solder is made. The other wire is coiled tightly around the outside of the air filled copper tube or lain up against it. The copper tube and the two wires are then enclosed inside a aluminum, steel, or brass hull with a packing media, such as silicone. This device when attached to a given seismic source such as a sledge hammer or weight drop will precisely, reliably provide a time zero, instantaneous recording point for seismic data.

Abstract: There is provided a sensor array, comprising a pair of transducers, a first transducer, configured to transmit pressure waves; and a second transducer, acoustically coupled to the first transducer, configured to detect pressure waves incident upon the sensor array from the environment. The array further comprises control circuitry, coupled to the first and second transducers, configured to: control the first transducer to transmit pressure waves; simultaneously control the second transducer to monitor the transmission of said pressure waves; and verify correct operation of the array in the event that said pressure waves are detected. The invention therefore provides a sensor array with a failsafe mechanism.

Abstract: An acoustic vector sensor mounted in a housing is provided for measuring ultra low frequency acoustic wave particle velocities in a liquid, comprising a horn for amplifying the acoustic wave particle velocities, and a neutrally buoyant object supported in a liquid contained in the horn. The neutrally buoyant object, in reacting to the amplified acoustic wave particle velocities, produces displacements that are sensitively measured.

Abstract: Disclosed is detecting changes in pressure in a medium, with an optical fiber having a core diameter at an immersion surface contact of the fiber of less than 10 ?m; a layer of material deposited on said end of the fiber, the material being of a thickness of from about 2 nm to about 10 nm. Also disclosed is detecting pressure waves in a medium comprising: contacting the medium with a fiber optic, the fiber integrated with a light source and a detector, the fiber optic having a diameter of less than 10 ?m at an immersion surface contact of the fiber; providing a thin layer of material on the immersion surface contact, wherein said thin layer of material is of a thickness in a range of from about 2 nm to about 10 nm; and detecting Fresnel back reflections from the immersion end of the fiber.

Abstract: The proposed bottom station relates to geophysical exploration, particularly to the geo-electrical seismic survey equipment. It's intended for prediction of hydrocarbons deposits and study of the deep structure of earth's crust. The station comprises a body, a load, a registration device. The station is characterized by placement of sensors in the lower part of body, in combination with the use of the load, having a cavity on the upper surface with a diameter exceeding the corresponding body's diameter. The body is releasably fastened to the load by means of Kevlar ropes. Additional accuracy of the station is achieved by the use of orthogonal three-component sensors, rather than cardan sensors, as well as by incorporating into the station's body an additional acoustic system for control of location of the station. Substitution of a hard drive by a flush memory card in the registration device increases reliability of storing and transmitting information.

Abstract: A capacitive membrane is used as a digital sensor. Membranes act as binary devices, such as being in a collapsed or non-collapsed state. By providing drum heads (membranes and associated gaps) with different response characteristics, the drum heads of an element digitally indicate the amplitude of the acoustic force by which of the drum heads are triggered or change states. The digital transducer may be used for different types of sensors, such as a CMUT, an air pressure, a temperature, a humidity, a chemical or biological stimulus or other sensor.

Abstract: A seismograph system includes a seismometer, a positioning unit, a transmitter, a remote processing device. The seismometer includes a micro electromechanical system (MEMS) accelerometer and a MEMS gyroscope. The seismometer, the positioning unit, and the transmitter being located at a detecting site. The MEMS accelerometer and the MEMS gyroscope are respectively configured for measuring an acceleration and an angular velocity of the movement of the earth at the detecting site. The positioning unit is configured for providing a location at the detecting site. The transmitter is configured for transmitting the measured acceleration, the measured angular velocity, and the provided location to the remote processing device. The remote processing device is positioned at a remote site and configured for analyzing recording the measured acceleration, the measured angular velocity, and the provided location.

Abstract: A seismic exploration method and unit comprised of continuous recording, self-contained wireless seismometer units or pods. The self-contained unit may include a tilt meter, a compass and a mechanically gimbaled clock platform. Upon retrieval, seismic data recorded by the unit can be extracted and the unit can be charged, tested, re-synchronized, and operation can be re-initiated without the need to open the unit's case. The unit may include an additional geophone to mechanically vibrate the unit to gauge the degree of coupling between the unit and the earth. The unit may correct seismic data for the effects of crystal aging arising from the clock. Deployment location of the unit may be determined tracking linear and angular acceleration from an initial position. The unit may utilize multiple geophones angularly oriented to one another in order to redundantly measure seismic activity in a particular plane.

Abstract: A marine seismic streamer includes a jacket substantially covering an exterior of the streamer. At least one strength member is disposed along the length of the jacket. A sensor mount is coupled to the strength member. At least one particle motion sensor is suspended within the sensor mount at a selected location along the jacket. The at least one particle motion sensor is suspended in the jacket by at least one biasing device. A mass of the particle motion sensor and a force rate of the biasing device are selected such that a resonant frequency of the particle motion sensor within the sensor jacket is within a predetermined range. The sensor mount is configured such that motion of the jacket, the sensor mount and the strength member is substantially isolated from the particle motion sensor.

Abstract: Advantageous online and/or real-time OFDM-based underwater acoustic (UWA) apparatus, systems and methods are provided according to the present disclosure. The apparatus, systems and methods employ a receiver with a bank of parallel branches, with each branch having a self-correlator matched to a different waveform scaling factor. A detection is declared when any of the branches leads to a correlation metric larger than a pre-defined threshold. The branch with the largest metric yields a Doppler scale estimate and a coarse synchronization point. The proposed apparatus, systems and methods use one OFDM preamble, thereby avoiding the need to buffer the whole data packet before data demodulation and enabling online and/or real-time operation. Thus, the disclosed apparatus, systems and methods are advantageously applicable to UWA communications.

Abstract: This scanning array scans an area around the array for nearby objects, collision obstructions, and terrain topography. The scanning array can scan for sounds emitted by objects in the vicinity of the scanning array, passive energy receipt sources, or it can also send out an energy beam and scan for reflections from objects within the energy beam. The energy beam can be optical, laser, radar or other energy emitting sources. The scanning array of the invention can be used for helicopter detection and avoidance of collision risk and can be used for other scanning purposes. Scanning of an entire hemisphere or greater is accomplished by manipulating the scanner platform through the coordination of either linear actuators or gimbals so as to produce nutation without rotation. This motion allows transceivers to be directly coupled to transmitting and sensing modules without the losses associated with slip rings and other coupling devices.

Abstract: A method of providing assistance to a driver for parking a vehicle includes detection of a space and a location of the vehicle for vehicle parking. The method determines a feasibility for parking the vehicle into the space based on the space; calculates a parking path based on the space and the location; generates a constant target position of a steering wheel based on the parking path; generates a first human machine interface (HMI) signal that instructs the driver to turn the steering wheel based on the target position, wherein the first HMI signal is generated when the vehicle is not moving; monitors a steering wheel angle of the vehicle including comparing the steering wheel angle with the constant target position, and detecting that the steering wheel angle reaches a proximity of the target position.

Abstract: Methods and apparatuses for finding, extracting and for providing of echoes with detail functions are described. In particular, an echo extraction method for extracting an echo from an echo function is described. The method comprises receiving the echo function and decomposing the echo function in at least one detail function. The at least one detail function comprises a plurality of first coefficients. Each of the at least one detail functions represents a different degree of detail of the echo function. The degree of detail relates to a form of a base function. Furthermore, the method comprises eliminating at least one of the plurality of first coefficients and applying a reconstruction regulation or scheme, which depends on the form of the base function, for generating a smoothed echo function. Thereafter, at least one echo is determined from the smoothed echo function.

Abstract: A sensor device (100) is adapted to be installed at a land-air interface. The sensor device (100) comprises a fluid-filled housing (101) and a sensor arrangement (102, 103) supported within the housing (101) and coupled directly to the fluid so as to detect movement thereof. A seismic sensor installation comprises a sensor device (100) installed at a land-air boundary, wherein the sensor device comprises a fluid-filled housing (101) and a sensor arrangement (102, 103) supported within the housing (101) and coupled directly to the fluid as to detect movement thereof.

Abstract: Platforms for detecting, identifying and/or designating objects. Platforms according to one embodiment of the invention include an extendable mast connected to a skid via a linkage that allows pivoting of the mast with respect to the skid, and preferably does not permit rotation of the mast; at least two actuators connected to the mast; at least one inclination sensor; at least one detection sensor connected to the mast for detecting presence of an object; and circuitry that receives information from the inclination sensors and plumbs the mast. Coupling and actuator mechanisms are disclosed for connecting the mast to the skid in a manner that allows the mast to be stable for accurate use of the sensors, yet easily and quickly deployable for such use, whether the platform is deployed from the bed of a truck or when the skid is on the ground and the mast is fully extended.

Abstract: Portable seismograph (1) comprising a support and containment structure (2), a bottom portion (3) of which is made of a material having a seismic impedance value ranging between 2×105 and 4×106 kg/m2s, three sensors (4) placed orthogonally to one another, each comprising at least one electrodynamic or capacitive transducer and, attached to the bottom portion (3), a level (11) to position the support and containment structure horizontally, a control unit (5) connected to the sensors (4) for viewing, managing the acquisition mode, recording and processing the data, a power source (9), and means for coupling to the ground (12; 21) designed not perturb the seismic tremor detectable by the sensors (4).

Abstract: A resonant-oscillating-device fabrication method for integrally forming a structure comprising a support, a beam vibratably extending from the support, and an oscillating element which is supported by the beam so as to oscillate in resonance with the vibration of the beam at a desired resonant frequency, by using a substrate. The resonant-oscillating-device fabrication method having a thickness measurement step of measuring the thickness of the substrate, an etching condition determination step of determining conditions of etching a portion forming the beam in the substrate to provide the desired resonant frequency, in accordance with the thickness of the substrate measured in the thickness measurement step, and an etching step of etching the substrate in accordance with the etching conditions.

Abstract: A broadband weak-motion seismometer includes: a frame, a mass, a suspension means for movably connecting the mass to the frame, a sensing transducer for measuring displacement of the mass with respect to the frame and for generating a sensing transducer output signal, which is a function of the measured displacement, a forcing transducer for applying a feedback force in a predetermined direction to the mass, and a control circuit. The control circuit receives the sensing transducer output signal and generates a forcing transducer input signal that includes a self-noise component. The forcing transducer input signal is processed by the forcing transducer to apply the feedback force to maintain the mass at rest with respect to the frame. The feedback force is sufficient to counterbalance a constant acceleration of the frame of at least 0.2 m/s2 in the predetermined direction of the feedback force.

Abstract: A seismograph system includes a seismometer, a positioning unit, a transmitter, a remote processing device. The seismometer includes a micro electromechanical system (MEMS) accelerometer and a MEMS gyroscope. The seismometer, the positioning unit, and the transmitter being located at a detecting site. The MEMS accelerometer and the MEMS gyroscope are respectively configured for measuring an acceleration and an angular velocity of the movement of the earth at the detecting site. The positioning unit is configured for providing a location at the detecting site. The transmitter is configured for transmitting the measured acceleration, the measured angular velocity, and the provided location to the remote processing device. The remote processing device is positioned at a remote site and configured for analyzing recording the measured acceleration, the measured angular velocity, and the provided location.

Abstract: A method of producing an electret condenser microphone capable of reflow mounting includes a first step of providing a backplate substrate having a backplate; a second step of providing an adhesive-backed fluorine-containing resin film formed by stacking an adhesive on a film-shaped fluorine-containing resin material having a surface treated by wet or dry chemical etching; a third step of stacking the adhesive-backed fluorine-containing resin sheet on the backplate of the backplate substrate with the adhesive interposed therebetween; a fourth step of setting the adhesive to firmly secure the fluorine-containing resin material to the backplate of the backplate substrate; and a fifth step of implanting electric charges into the fluorine-containing resin film firmly secured onto the backplate.

Abstract: The current invention minimizes the energy losses by pointing the geophone's internal system, which consists of a magnet bar, coil, and springs, towards signals reflected from targets.

Abstract: An arrangement for the deployment of seismic sensor units, such as sensor nodes (24), on the seabed includes a frame structure that is adapted to carry a container (11) for containment of a data registration unit and additional auxiliary equipment for the sensor node. The arrangement has supports (12, 13) that can rest against the seabed, and an attachment means (17) for a lifting hook, for raising and lowering by means of a crane. There is a holder (20) for the sensor node (24) that can be positioned on the seabed and which is connected to the container through a signal cable (32). A releasable attachment means (22) holds the sensor node (24) in a downwardly extending position with respect to the supports (12, 13). The attachment means (22) is located with a horizontal distance from the container (11). A latch mechanism (25) for the attachment means (22) is adapted to release the sensor node (24).

Abstract: Apparatus and methods for acquiring seismic data using a seabed seismic data cable positioned on a seabed are described, including correcting for the effect of one or more sensor non-linear motions, which improves accuracy of seismic data. One or multiple non-linear movements of the sensor may be corrected for. It is emphasized that this abstract is provided to comply with the rules requiring an abstract, which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.

Abstract: A method and system for using two-dimensional transducer arrays for improving the field of view during an ultrasonic examination are disclosed. The ultrasonic imaging system includes a two-dimensional transducer array with a plurality of acoustic elements, a beam controller, a signal processor, and a display. The beam controller controls a generated acoustic beam capable of being advanced longitudinally or laterally along the two-dimensional transducer array. Additionally, the generated acoustic beam is capable of being phase-shifted by the beam controller. Combining the phase shifting of and advancement of the acoustic beam increases the field of view of the two-dimensional array.

Abstract: A scanner device for performing nondestructive testing of a tube includes an ultrasonic probe, a waveguide (wedge) secured relative to the probe, and an encoder secured relative to the probe. The waveguide has a surface contoured in relation to a radius of a tube to be inspected, and the encoder provides a signal indicative of a location of the probe relative to the tube as the probe, waveguide, and encoder are moved in a direction of a longitudinal axis of the tube. In one example, the tube is part of a waterwall, and the surface of the waveguide extends substantially from a web on one side of the tube to a web on the opposite side of the tube. The waveguide may be removably secured relative to the probe such that the waveguide can be replaced with a waveguide having a different surface contour in relation to a different radius of a different tube to be inspected.

Abstract: A particle motion sensor, includes: a sensing element capable of sensing a particle motion vector from a change in position thereof, and a packing material in which the sensing element is positioned, wherein the particle motion sensor is symmetric about its longitudinal axis and has a center of gravity coincident with its volumetric center. An apparatus includes a streamer; a plurality of acoustic sensors distributed along the streamer; and a plurality of particle motion sensors distributed along the streamer, at least one particle motion sensor being symmetric about its longitudinal axis and having a center of gravity coincident with its volumetric center.

Abstract: A particle motion sensor, includes: a sensing element capable of sensing a particle motion vector from a change in position thereof, and a packing material in which the sensing element is positioned, wherein the particle motion sensor is symmetric about its longitudinal axis and has a center of gravity coincident with its volumetric center. An apparatus includes a streamer; a plurality of acoustic sensors distributed along the streamer; and a plurality of particle motion sensors distributed along the streamer, at least one particle motion sensor being symmetric about its longitudinal axis and having a center of gravity coincident with its volumetric center.

Abstract: Processes and systems for detecting a shot by a projectile weapon are disclosed. Data is obtained along at least two different axes for use in determining whether a shot has taken place based on an evaluation by a processor. In certain embodiments, multiple detection systems are positioned on a weapons platform mounting multiple projectile weapons, and each is configured to detect only a shot by a respective one of the projectile weapons.

Abstract: The apparatus has a sensor disposed on the first end of an elongate connector by means of fixed interface link. A recorder unit is disposed on the second end of the connector opposite the first end. The connector is bendable within a predefined curvature range. When the apparatus is deployed into the sea, it is adapted to free-fall through the body of water and to land on the seafloor such that the sensor is spaced apart from the recorder unit. The apparatus is additionally adapted to substantially vibrationally de-couple the sensor from the recorder unit. The length of the connector is dynamically variable within a predefined range so as to minimize vibration coupling between the recorder unit to the sensor. Physical separation of the sensor and the recorder unit, together with the mechanical characteristics of the connector, ensure that the sensor is substantially vibrationally de-coupled from the recorder unit.

Abstract: A seismic exploration method and unit comprised of continuous recording, self-contained wireless seismometer units or pods. The self-contained unit may include a tilt meter, a compass and a mechanically gimbaled clock platform. Upon retrieval, seismic data recorded by the unit can be extracted and the unit can be charged, tested, re-synchronized, and operation can be re-initiated without the need to open the unit's case. The unit may include an additional geophone to mechanically vibrate the unit to gauge the degree of coupling between the unit and the earth. The unit may correct seismic data for the effects of crystal aging arising from the clock. Deployment location of the unit may be determined tracking linear and angular acceleration from an initial position. The unit may utilize multiple geophones angularly oriented to one another in order to redundantly measure seismic activity in a particular plane.

Abstract: This Passive Long Range Acoustical Sensor relates to means of sensing acoustical sources and signals, including multi-channel acoustical signals, such as various types of sounds, vibrations, flutter, turbulence, and the like, and at long distances through a natural optical channel, without the use of a laser or other artificial illuminating means. A modified multi-channel embodiment of the Passive Long Range Acoustical Sensor may use a combination of natural optical channels and active illumination means, such as laser or other artificial illuminating means, of producing additional optical channels.

Abstract: A motion sensing element with position sensing includes a case, a magnet positioned within the case, a spring assembly having an electrically conductive member and a coil assembly coupled to the spring assembly. The coil assembly and magnet are moveable with respect to one another. A capacitor plate is proximate the electrically conductive member with a distance between the capacitor plate and electrically conductive member being variable as the magnet and coil assembly move. Leads connect the capacitor plate and electrically conductive member to a sensing circuit for estimating the relative positions of the magnet and coil assembly.

Abstract: A method for transmitting an ultrasonic wave is disclosed. The method includes: selecting a first combination of transmission elements from among multiple transmission elements, wherein the first combination of transmission elements includes at least two transmission elements adjacent to each other; and vibrating the transmission surfaces of the first combination of transmission elements in a substantially same phase to transmit the ultrasonic wave with a first directivity. The first directivity is different from a second directivity of the ultrasonic wave transmitted from single transmission element.

Abstract: Reflective and slanted array channelized sensor arrays having a broadband source providing acoustic energy to a reflective or slanted array that reflects a portion of the incident signal to one or more sensing films wherein the response is measured.

Abstract: A seismic data acquisition system includes a plurality of sensors which are arranged so they can be used to measure translation movements of a medium with three independent spatial components and of the rotation movements around each of the three independent spatial components, thus forming a six-component system.

Abstract: A method for making a diaphragm unit of a condenser microphone includes the steps of: forming a liftoff layer on a substrate; forming an insulator diaphragm film on the liftoff layer; and removing the liftoff layer from the diaphragm film and the substrate so as to separate the diaphragm film from the substrate.

Abstract: A defensive aids suite for light armored vehicles utilizes four complementary sensor technologies including: visible and infrared optics, radar, acoustics and both laser and millimeter wave detection. Targeting and maneuvering optics are used for long-range threat detection with obscuration grenades and vehicle countermaneuvers being used to avoid a threat. Short range search and track radar is used with explosive or fragmentation grenades selected and launched to intercept and defeat the threat. Acoustic threat detection increases robustness and extends the detection range to include small calibers threats. Detection of active targeting systems by laser and radar warning receivers provides cueing information for targeting optics and fire control systems.

Abstract: A sensor assembly includes a seismic sensor element and a shell. The shell at least partially surrounds the sensor element to shield the sensor element from a magnetic field that is generated outside of the shell.

Abstract: This Passive Long Range Acoustical Sensor relates to means of sensing acoustical sources and signals, including multi-channel acoustical signals, such as various types of sounds, vibrations, flutter, turbulence, and the like, and at long distances through a natural optical channel, without the use of a laser or other artificial illuminating means. A modified multi-channel embodiment of the Passive Long Range Acoustical Sensor may use a combination of natural optical channels and active illumination means, such as laser or other artificial illuminating means, of producing additional optical channels.

Abstract: In the present invention, a seismic receiver contains an onboard digitizer that samples and converts a signal from detected seismic energy into the digital domain. The receiver contains an analog to digital converter, a transmission circuitry, and a link to the seismic detection circuitry. The signal from the seismic detection circuitry is converted into a digital signal, which is then relayed to the data recorder. These components are all resident to the receiver itself. Additional control circuitry is employed to provide clocking and testing functions. These receivers communicate with one another, and provide sampled seismic data on an individual basis. The components may be prepared on a PCB and put inside the receiver cap. The PCB may be flexible in nature, as to provide a maximum of surface mounted components in the smallest amount of space.

Abstract: A seismometer comprising a pressure sealed enclosure; an electrical component; an axis mechanics assembly having moving components, the axis mechanics assembly being in electrical communication with the electrical component; and a thermally insulating assembly mechanically supporting and surrounding the axis mechanics assembly for minimizing heat flow from the pressure sealed enclosure to the axis mechanics assembly and for enabling transmission of a seismic signal to the axis mechanics assembly, wherein the pressure sealed enclosure encloses the axis mechanics assembly, the thermally insulating assembly, and the electrical component.

Abstract: A sensor assembly includes a seismic sensor element and a shell. The shell at least partially surrounds the sensor element to shield the sensor element from a magnetic field that is generated outside of the shell.

Abstract: A method for making condenser microphones includes: forming a fixed electrode layer structure of a plurality of fixed electrode units; forming a sacrificial layer of a plurality of sacrificial units on one side of the fixed electrode layer structure; forming a diaphragm layer structure of a plurality of diaphragm units on the sacrificial layer; forming a patterned mask layer on an opposite side of the fixed electrode layer structure opposite to the sacrificial layer; forming a plurality of etching channels, each of which extends through the patterned mask layer and the fixed electrode layer structure; removing a portion of the sacrificial layer of each of the sacrificial units so as to form a spacer between a respective one of the fixed electrode units and a respective one of the diaphragm units; and removing the patterned mask layer.

Abstract: A marine seismic exploration method and system comprised of continuous recording, self-contained ocean bottom pods characterized by low profile casings. An external bumper is provided to promote ocean bottom coupling and prevent fishing net entrapment. Pods are tethered together with flexible, non-rigid, non-conducting cable used to control pod deployment. Pods are deployed and retrieved from a boat deck configured to have a storage system and a handling system to attach pods to cable on-the-fly. The storage system is a juke box configuration of slots wherein individual pods are randomly stored in the slots to permit data extraction, charging, testing and synchronizing without opening the pods. A pod may include an inertial navigation system to determine ocean floor location and a rubidium clock for timing. The system includes mathematical gimballing. The cable may include shear couplings designed to automatically shear apart if a certain level of cable tension is reached.

Abstract: A pressure gradient sensor for seismic and other applications utilizing the principle of diamagnetic drift. The sensor comprises at least one transducer, each transducer made of or containing a medium having at least one species of mobile charged particles such as electrons or holes that exhibit diamagnetic drift under a pressure gradient. A magnet and a pair of electrodes are installed in each transducer. Diamagnetic drift current collected by the electrodes can be measured by an ammeter or similar device, and formulas and methods are disclosed to determine the pressure gradient from the measured current.

Abstract: An electronic surface tunneling acoustic detector or microphone with very high sensitivity is disclosed. A tunneling tip is mounted on a rigid perforated suspension plate, along with control electrodes, which are used to move a conductive membrane suspended above the suspension plate into closer or farther proximity with the tunneling tip. An electrical potential between the control electrodes and membrane, causing the membrane to bend towards the electrodes, and hence the tip, due to electrostatic attraction. As the membrane is pulled toward the tunneling tip, at some point a tunneling current begins to flow in the tunneling tip. The control voltage is subsequently adjusted to achieve a steady-state tunneling current in the tip. As the membrane responds to differential acoustic pressure variations, it moves and therefore upsets the adjusts the control voltage to return the membrane to the steady-state condition.

Abstract: A particle motion sensor, includes: a sensing element capable of sensing a particle motion vector from a change in position thereof, and a packing material in which the sensing element is positioned, wherein the particle motion sensor is symmetric about its longitudinal axis and has a center of gravity coincident with its volumetric center. An apparatus includes a streamer; a plurality of acoustic sensors distributed along the streamer; and a plurality of particle motion sensors distributed along the streamer, at least one particle motion sensor being symmetric about its longitudinal axis and having a center of gravity coincident with its volumetric center.