Abstract: A reconfigurable linear array of sensors (e.g., optical, thermal, pressure, ultrasonic). The reconfigurability allows the size and spacing of the sensor elements to be a function of the distance from the beam center. This feature improves performance for imaging systems having a limited channel count. The improved performance, for applications in which multiple transmit focal zones are employed, arises from the ability to adjust the aperture for a particular depth.

Abstract: The present invention provides a method and apparatus for seismic data acquisition. One embodiment of the method includes accessing data acquired by at least two particle motion sensors. The data includes a seismic signal and a noise signal and the at least two particle motion sensors being separated by a length determined based on a noise coherence length. The method may also include processing the accessed data to remove a portion of the noise signal.

Abstract: A system is disclosed that provides an improvement in detecting a faulty hydrophone channel in a hydrophone array. The disclosed technique operates on pairs of hydrophones or, to generalize, on groups of two or more hydrophones; this is in contrast with operating on only one hydrophone at a time. As a result, the technique is able to use correlation data from the multiple hydrophones, in order to detect a fault. The technique also operates on received echo signal information that is associated with ongoing SONAR solution processing. The use of the relatively deterministic, echo signal information further enhances the performance. By using correlation products made up of the received echo signal information, the disclosed technique is able to leverage the SONAR solution processing that already relies upon the hydrophone array, such as spatial or temporal correlation SONAR, thereby reducing the additional processing incurred.

Abstract: Seismic sensor systems and sensor station topologies, as well as corresponding cable and sensor station components, manufacturing and deployment techniques are provided. For some embodiments, networks of optical ocean bottom seismic (OBS) stations are provided, in which sensor stations are efficiently deployed in a modular fashion as series of array cable modules deployed along a multi-fiber cable.

Abstract: An acoustic transducer 1 has a first cylindrical portion 1A and a second hemispherical portion 1B on which a plurality of transducer elements 10a, 10b are arranged. The transducer elements on the cylindrical portion are arranged to have six nearest neighbors. The arrangement may be such that the six transducer elements surrounding a given element describe the vertices of a regular hexagon. The hexagons thus described may be aligned so that two of their sides are parallel to the axis of the cylinder. The elements on the hemispherical portion may be arranged so that some elements have five nearest neighbors and others have six (the neighboring elements describing, for example, the vertices of hexagons and pentagons respectively). An underwater sounding apparatus may be constructed using the transducer.

Abstract: A hydrophone array includes hydrophones having an electret means and may have TFT FETs to generate current in response to received longitudinal wave signals. The arrangement may also be used to transmit longitudinal wave signals. Storage capacitors may be coupled to each TFT FET output to act as sample and hold means. Digital switches may allow the sample and hold circuit to both reset and measure the output of the hydrophone element. Data lines may be used to indicate the location of the received signal on the longitudinal wave detector sensor array.

Abstract: A scanning architecture that makes it possible to update only those ultrasonic transducer subelements of a mosaic transducer array that change from view to view. The configuration of the switch matrix is fully programmable. The switch matrix includes access switches that connect subelements to bus lines and matrix switches that connect subelements to subelements. Each subelement has a unit switch cell associated therewith, each unit switch cell comprising at least one access switch, at least one matrix switch, and addressing and control logic. Optionally, each unit switch cell also includes latches for storing the future switch states of the switches to be programmed. The switches themselves have memory for storing their current switch states.

Abstract: A method that involves establishing the performance level of a proposed acoustic transducer array. Deriving a geometric shape for the array based on the established performance level. Selecting piezoceramic materials based on considerations related to the performance level and derived geometry. Forming small primary shapes of the selected piezoceramic materials for use as the basic elements of the larger derived geometric shape of the array. Arranging the basic elements into a mosaic of the larger derived geometric shape. Filling the interstices between the basic elements with urethane to bind the mosaic of basic elements thereby fabricating the completed piezoceramic transducer array.

Abstract: A device comprising an array of sensors that are reconfigurable by means of a switching network. The sensors may be optical, thermal or pressure sensors or ultrasonic transducers.

Abstract: An integrated switch matrix for reconfiguring subelements of a mosaic sensor array to form elements. The configuration of the switch matrix is fully programmable. The switch matrix includes access switches that connect subelements to bus lines and matrix switches that connect subelements to subelements. Each subelement has a unit switch cell comprising at least one access switch, at least one matrix switch, a respective memory element for storing the future state of each switch, and a respective control circuit for each switch. The access and matrix switches are of a type having the ability to memorize control data representing the current switch state of the switch, which control data includes a data bit input to turn-on/off circuits incorporated in the control circuit. The sensor array and the switching matrix may be built in different strata of a co-integrated structure or they may be built on separate wafers that are electrically connected.

Abstract: A transducer for use in an acoustic energy cleaner is provided. The transducer includes a resonator and a plurality of crystals bonded to a surface of the resonator. The plurality of crystals is configured to be bonded to the surface of the resonator in a staggered arrangement with respect to each other. In one embodiment, the plurality of crystals is bonded to the surface of the resonator in a horizontally staggered arrangement. In another embodiment, the plurality of crystals is bonded to the surface of the resonator in a vertically staggered arrangement.

Abstract: An apparatus and method is provided for transporting, installing, retrieving, and replacing a sensor array of individual sensor pods at a geographically remote location, such as on the sea floor. The apparatus consists of a remotely operated vehicle (ROV), a carousel attached to the ROV, a pod ejector mechanism attached to the carousel, and a manipulator with a manipulator end effector attached to the ROV. The carousel contains a plurality of sensor pod holders, where each sensor pod holder is capable of holding a sensor pod. The pod ejector mechanism is capable of discharging a fresh sensor pod, while the manipulator end effector is capable of lifting a depleted sensor pod and placing the depleted sensor pod in an empty sensor pod holder in the carousel.

Abstract: A method for wrapping continuous strands of steel wire about a seismic cable including interconnected sensor sections and conductor sections where a cross sectional diameter of the sensor section is at least four times that of the conductor section. Two layers of armoring are provided with a first layer wrapped in a first angular direction opposite that of the second layer. A stranding assembly is provided which has two selective positions, one for providing a die hole for stranding the conductor section, another for providing a passage hole for allowing the sensor section to pass after wrapping with armor wire.

Abstract: A hydrophone stave comprises a tubular member, a braided cord (or similar flexible structure), cylindrical hydrophones, pins, two plugs and two couplings. The hose (made of a thermoplastic material) is corrugated or convoluted, and is cuffed at both ends to permit a plug to engage at each end. Each coupling includes a wire rope (or similar flexible structure). Each hydrophone has a longitudinal through-aperture (through which the braided cord passes) and a perpendicularly transverse through-aperture (through which a pin passes while also passing through a void created between strands of the braided cord). The stave is suitable for incorporation into a hydrophone array assembly providing for a selected arrayal of hydrophones, e.g., an assembly including two opposite frames united therebetween by numerous congruous parallel staves, each stave including equally spaced hydrophones, each coupling linking a plug with a frame so that the staves are selectively arranged.

Abstract: An electronic-carrying module (640), for example for use with a seismic data acquisition cable (400), is disclosed. The preferred electronic-carrying module (640) includes, first, an electronics carrier (106) having access means (107) for providing an easy-to-reach access to wrap-around circuitry fitted inside a curved space (104a) within the electronics carrier (106). Second, a pair of rigid end-fittings (102) spaced apart axially by the electronics carrier (106) for connecting to a section of the seismic data acquisition cable (400). And third, an axial hole (100) formed in the electronics carrier (106) and the rigid end-fittings (102) defining the curved space (104a) between the axial hole (100), the access means (107) and the rigid end-fittings (102).

Abstract: Method and apparatus for locating and quantifying sound sources using an array of acoustic vector probes (200). Signals received at the probes are converted to digital form and fed into a digital signal processor (400) which computes the sound pressure and the sound-intensity vector at each probe. The set of sound-intensity vectors measured by the array provides a set of directions to a sound source (100) whose approximate spatial coordinates are determined using a least-squares triangulation formula. The sound-intensity vectors also determine sound-power flow from the source. In addition sound pressure measured by the probes can be phased to form a sensitivity beam (250) for scanning a source. Sound-intensity measurements made concurrently can be used to determine the spatial coordinates of the part being scanned and the sound power radiated by that part. Results are displayed on a computer screen or other device (500) permitting an operator to interact with and control the apparatus.

Abstract: A marine acoustic source system has relativley densely packed energy sources arrayed in a tandem-like fashion along a horizontal plane. Preferably, a longitudinal axis of each source lies orthogonal to a pre-determined towing direction. The system includes protective tubes that encloses supply lines and auxiliary equipment, and a harness. The harness provides the primary mechanical connection for towing the sources through the water. To minimize bending of the supply lines, connectors having angular portions connect the sources to the supply lines. Further, the sources can be arranged such that source connection interfaces for receiving power, hydraulic fluid, or data point alternately in opposing directions. During use, the sources, e.g., air guns, are supported at a predetermined depth beneath the water's surface by a floatation buoy. Upon activation, the sources of a cluster each release individual air bubbles into the water.

Abstract: A multi-layer composite transducer array includes at least one pair of composite transducers with an electrical and mechanical isolation layer disposed therebetween. Each composite transducer is defined by a composite panel having a common electrode coupled to a first surface and electrode segments electrically isolated from one another and coupled to a second surface. Each pair of composite transducers is configured such that the electrode segments associated with the pair's composite transducers oppose and are aligned with one another. The isolation layer has dielectric material segments that are sized, shaped and aligned in correspondence with opposing and aligned ones of the electrode segments associated with the pair's transducers. Spaces formed in the isolation layer between the dielectric material segments are filled with a viscoelastic material.

Abstract: A cable for towing marine devices is disclosed. The cable includes a strength member and at least one conduit associated with the strength member. The conduit has apertures therein at selected locations along the conduit. The apertures are adapted to conduct gas from a source into water in which the cable is disposed. Also disclosed is a method for improving the flow of a cable through water. The method includes releasing a gaseous bubble stream proximate an outer surface of said cable while the water is moving relative to the cable.

Abstract: A staggered vertical marine seismic source contains upper and lower arrays (10, 11) of emitters of seismic energy (S11, S12; S21, S22). The upper array (10) is horizontally displaced relative to the lower array (11). The source is used in a marine seismic surveying arrangement that has means for moving the source and at least one seismic receiver. In use, the source is moved through the water in a direction parallel to the direction in which the two arrays are displaced. The arrays (10, 11) are fired sequentially, and the time delay between the firing of the first-fired array and firing of the second-fired array is chosen such that each seismic emitter in one array is fired at the same x- and y-co-ordinates as the corresponding emitter in the other array. The seismic wavefields generated by firing the two arrays are thus generated at the same x- and y-co-ordinates, but at different depths.

Abstract: A termination assembly for use in an optical hydrophone module, comprising a module oil seal and an optical fiber seal. The termination assembly is used at the ends of modules and provides a means for filling individual modules with fill fluid. A module oil seal comprises a cylindrical wall defining a cavity, with one end substantially closed and the other end open. An annular face plate on the open end makes a seal dividing a coupling and a clevis. A check valve is mounted to an orifice that passes through the substantially closed end of the module oil seal. Optical fibers pass through the substantially closed end and the optical fiber seal is provided around the optical fiber that passes therethrough. The fiber seal fits snugly in a module oil seal opening. Both components serve to provide a seal that can withstand high pressures and maintain optical fiber integrity.

Abstract: Method and apparatus for acoustic detection, location and identification of a buried object using a source emitting bursts of sound that penetrate the ground and return echoes from the object to an array of acoustic vector probes (200) located above the ground. Echoes recorded at the probes in the array, are converted to digital form and fed into a digital signal processor (400) which computes the sound-intensity vector at each probe. Results are displayed on a computer screen or other device (500) permitting an operator to interact with and control the apparatus. The processor controls gating of the bursts of pulsed sound and the duration of the reception of echoes by the array. Additional related features and methods are disclosed.

Abstract: An integrated high-voltage switching circuit includes a switch having ON and OFF states and having a parasitic gate capacitance. The switch consists of a pair of DMOS transistors integrated back to back and having a shared gate terminal, the drains of the DMOS transistors being connected to the input and output terminals of the switch respectively. The switching circuit further includes a turn-on circuit comprising a PMOS transistor having its drain connected to the shared gate terminal of the switch via a first diode, having its source connected to a global switch gate bias voltage terminal from which the PMOS transistor draws current, and having its gate electrically coupled to a switch gate control terminal that receives a switch gate control voltage input.

Abstract: A dynamically configurable ultrasound transducer element and related circuits and methods. The transducer may comprise an array of capacitive transducer elements, a row decoder coupled to said array of capacitive transducer elements, a column decoder coupled to said array of capacitive transducer elements, a bias voltage source coupled to said row decoder, and a driving signal source coupled to said column decoder. Preferably, a master clock also is provided to allow for a synchronization of signals between the row decoder and column decoder.

Abstract: A encapsulation method of an acoustic sensor module and a resultant lightweight watertight acoustic sensor module for use in towed array retrieval systems. In the method, a composite is cast to encapsulate the support between end plates of the module, an exterior of a passage tube in which the array is retrieved, transducers positioned on the tube exterior and supporting telemetry lines for the transducers. The components, listed previously, are cast into a block of the cured composite such that the arrangement of the components is fixed. Residual composite emitting from an aperture of an end plate allows a conductor for the telemetry lines to be potted into the composite with an end of the conductor free from the composite thereby allowing connection to an external controller or generator.

Abstract: A seismic sensor contains a geophone (4) disposed within a housing (12). The sensor is also provided with locking means (14, 19, 21) that can either lock the geophone 4 relative to the housing, or can allow the geophone to rotate within the housing. The geophone (4) is enclosed in a casing (1) which is so constructed that the overall mass distribution of the casing and geophone is uneven. The casing and geophone assembly thus adopts a preferred orientation when the sensor is unlocked. A liquid can be disposed within the housing, so that the casing (1) and geophone (4) can float when the sensor is unlocked.

Abstract: A system for sonically probing a seabed comprises at least one row (14) of transducers (22) that each can produce a sonic beam, and at least one sonic detector (24). Each transducer is independently energized to produce a narrow sonic beam (40), with resulting seabed or subsea echoes being detected to produce one pixel of a display (60, 80, 90, 150) formed by an X-Y array of pixels, before a next transducer is energized and its echoes are detected to produce another pixel of the display. When the system detects a large change in echo amplitude at adjacent seabed locations, then scanning at those locations is accentuated by analysis and by additional sonification at different frequencies. The transducers are closely spaced, at a center-to-center distance (G) of less than 25 cm, to provide good horizontal resolution and usually lie within 6 meters from the seabed. Each transducer is energized to produce a sonic pulse which, dependent on the application, has a carrier frequency (32) of at least 200 kHz.

Abstract: An underwater acoustic transducer includes a set of formed substrates of piezoelectric polymer composite, the formed substrates having at least a first and second surface. Conductive electrodes are deposited on the first and second sides of the formed substrates. One surface of the substrate is bonded to an acoustically absorptive backing material. Either surface can be made to conform to a singly or doubly curved geometry. Electrodes deposited on these substrates may be continuous to form a single transducer element, or segmented to form sub-arrays of transducer elements.

Abstract: A sonar array comprising a support structure, an acoustic projector attached to the support structure, and a plurality of directional hydrophones attached to the support structure and arranged so as to surround the acoustic projector. The directional hydrophones are equidistantly spaced about the acoustic projector. In one embodiment, the array includes means attached to the support structure that allows the support structure to be connected to a device that effects course steering of the sonar array.

Abstract: For reducing the number of acoustic transducers required by a torpedo sonar for target searching, the transducers are arranged in four particular zones at the curved contour of the torpedo bow forming a conformal sonar array. The circular first zone covers the vertex region of the torpedo bow and is surrounded by a ring-shaped second zone. Extending from the second zone on both sides of the torpedo are third lateral transition zones, which change over into fourth lateral zones of constant width ending at the great circle of the hemispherical or paraboloid-shaped torpedo head.

Abstract: A three-dimensional array of acoustic sensors. The array can be used for both the transmission and reception of acoustic signals. The array comprises electroplated piezoelectric polymer layers that are laminated with a non-conductive epoxy to form individual multi-layer array transducer elements. Circuit support layer layers are incorporated between the multi-layer array transducer elements. Because of the three-dimensional configuration of the array, logical transducers can be created from multiple transducer elements, and transmission and reception of acoustic signals in any direction can be realized.

Abstract: A noise cancellation system and method for use with a seeker head of a marine vessel are provided according to the invention. The seeker head employs one or more hydrophones that generate one or more output signals. The noise cancellation system includes a plurality of motion sensors. The plurality of motion sensors generate a plurality of noise signals based on a hydrodynamic flow noise caused by the marine vessel and acting on the marine vessel. The noise cancellation system further includes a processor receiving the plurality of noise signals and the one or more output signals and applying an active noise cancellation to the one or more output signals to substantially cancel out the flow noise. The active noise cancellation is based on the noise signal.

Abstract: For reducing the number of acoustic transducers required by a torpedo sonar for target searching, the transducers are arranged in four particular zones at the curved contour of the torpedo bow forming a conformal sonar array. The circular first zone covers the vertex region of the torpedo bow and is surrounded by a ring-shaped second zone. Extending from the second zone on both sides of the torpedo are third lateral transition zones, which change over into fourth lateral zones of constant width ending at the great circle of the hemispherical or paraboloid-shaped torpedo head.

Abstract: A hydrophone array including a cable, such as a towing cable, having attached thereto a plurality of housings. Each housing encloses two acoustic transducers that act as acoustic receivers and acoustic transmitters as requirements dictate during use of the array. The acoustic transducers can comprise piezoelectric transducers, including piezoelectric polymeric transducer materials. Each housing can be hydrodynamically smoothly shaped and have a first bend limiting means extending forwardly from a nose section thereof and a second bend limiting means extending rearwardly from a tail section thereof.

Abstract: An ultrasonic diagnostic apparatus for observing a detectable object to be ultrasonically diagnosed. The apparatus includes an ultrasonically diagnostic probe unit for probing the object with ultrasonic waves in response to input pulse signals and with an ultrasonic echo from the object, a signal transmitting unit to generate the input pulse signals, a signal receiving unit for receiving the ultrasonic echo and processing output signals to be converted into an image of the object, and a display unit to display the image.

Abstract: Towed low-noise linear acoustic antennas configured for seismic exploration. The jacket of this antenna is pierced with holes that allow seawater to enter the inside of the antenna. The hydrophones are isolated by enclosing them in polyurethane envelopes filled with oil or gel. Buoyancy is ensured by lightening the jacket with hollow inclusions formed from microspheres. Such a structure allows the output noise level of the hydrophones to be reduced by 15 dB.

Abstract: A dynamically configurable ultrasound transducer element and related circuits and methods. The transducer may comprise an array of capacitive transducer elements, a row decoder coupled to said array of capacitive transducer elements, a column decoder coupled to said array of capacitive transducer elements, a bias voltage source coupled to said row decoder, and a driving signal source coupled to said column decoder. Preferably, a master clock also is provided to allow for a synchronization of signals between the row decoder and column decoder.

Abstract: A logging tool having a tool body, which can be positioned in a fluid-filled borehole, including a receiver section and a dipole transmitter; wherein the dipole transmitter includes a transducer with a shell having a reaction mass and a motor located therein, the motor operatively connecting the shell and the reaction mass such that only an outer surface of the shell is in contact with the fluid in the borehole. This new type of dipole source for well logging involves shaking all or part (axially) of a dipole tool body to produce a pure, broadband acoustic dipole signal while at the same time coupling as little energy as possible into the tool body. Important variations on this idea include a linear phased array of shaker sources, and active cancellation of tool borne noise.

Abstract: A system is disclosed that provides. a sonar operator with the most likely range to a target of interest. The system generates and displays a contour based on ship's parameters, target parameters, environmental data, and operator parameters. The sonar operator can vary many of the parameters in “what if” scenarios so as to generate groups of contours for preselected probabilities of detection. Contours can be used to show the actions that should be taken to ensure a favorable outcome.

Abstract: A loudspeaker system has a plurality of loudspeaker elements (23), and a transmitter (33) for transmitting information in the form of a beam (34) to the loudspeaker elements. The information may be transmitted in parallel to each element. A selection means (31) is provided so that sound is only reproduced by the intended loudspeaker element or elements. The information is transmitted in digital form.

Abstract: For reducing the number of acoustic transducers required by a torpedo sonar for target searched the transducers are arranged in four particular zones at the curved contour of the torpedo bow forming a conformal sonar array. A circular first zone covers the vertex region of the torpedo bow and is surrounded by a ring-shaped second zone. Extending from said second zone on both sides of the torpedo are third lateral transition zones, which change over into fourth lateral zones of constant width ending at the great circle of said hemispherical or paraboloid-shaped torpedo head. (FIG.

Abstract: Sonobuoy apparatus which fits into an A sized canister for use in the water environment. The apparatus includes an array of telescopic arms connected by hinges to a housing which contains receiver transducer electronics. An acoustic projector bears against projections on the last arm section of each arm such that it will cause the nested arm sections to extend while dropping through the water. When the canister falls free, an arm deployment arrangement causes the arms to assume a horizontal orientation. These deployed arms carry receive transducers for detecting acoustic echos from a potential target.

Abstract: A system to extend transducer arrays from the hull of a vessel while it is underway provides for increased array gain, volumetric aperture (very large aperture arrays), and rejection of hull-bound noise for submarines, surface ships, weapons, and unmanned underwater and surface vehicles. A plurality of arms extend radially outwardly from the hull of a submarine, and passive and/or active elements of the arrays are mounted around the hull on the arms, trail in the water from the arms, or extend between different ones of the arms or between arms and the hull. The system of arms and the array are folded into elongate recesses in the hull to lower noise during higher speed transit by the submarine. The arrays can be made up of sensors and/or projectors of radar, sonar signals, optical energy, vibrational energy, magnetic influence, temperature, etc., and combinations of these sensors.

Abstract: A system for sensing subterranean acoustic waves emitted from an acoustic source includes a plurality of laser sources, a plurality of subterranean optical sensors, at least one optical detector, and electronics. The laser sources each emit light at a different frequency. The subterranean optical sensors receive the light and alter the light in response to the acoustic waves. The optical detector receives the altered light and outputs an electrical signal. The electronics receives the electrical signal and converts it into seismic data format. Preferably, the light emitted from the optical sources is modulated at a plurality of modulation frequencies. The electronics can be used to demodulate the signal. The electronics may demodulate the electrical signal by mixing the signal with periodic waveforms having frequencies corresponding to the modulation frequencies and twice the modulation frequencies.

Abstract: There is described a capacitive micromachined ultrasonic transducer array which is configured to minimize the excitation and propagation of plate waves traveling in the substrate and ultrasonic waves propagating at the interface between the array surface and the immersion fluid.

Abstract: A dipping sonar transducer housing includes a generally cylindrical housing (10) which is suspended at the end of a cable (12) connected to tile housing through a vibration isolation module (14) which includes springs (22) to damp out noise, particularly that from the supporting vehicle. The housing (10) contains an upper water-tight chamber (26) which contains circuit boards (28) and preamplifiers (30) which serve as amplification and multiplexing means for the hydrophones carried on extendible arms (96, 60, 88); a second water-tight chamber (35) immediately below the first chamber (26) contains an electric motor (36) which drives a hydraulic pump (38) which provides fluid under pressure to an accumulator (40). Movable vertically on the outside of the second chamber (35) is a piston (48) which drives a plurality of links (54, 56) which extend the receiver array.

Abstract: Apparatus for studying the variations in hydrodynamic pressure for correlation with fish movement towards and away from zones of danger comprises a hollow winged section having mounted on the surface thereof, piezoelectric sensors, and an accelerometer mounted within the apparatus, for generating electrical signals that are processed and interpreted by remote electronic means.

Abstract: A method and device for generating a high amplitude sound wave is provided. The device includes a housing having an open end. A piston is slidably disposed in the open end of the housing and forms a chamber for holding a pressurized liquid. The pressurized liquid acts on the piston to move the piston relative to the housing. A latch is operable to fix the piston relative to the housing and to release the piston. Upon release of the latch, the piston moves relative to the housing to generate the sound wave. In the method of the present invention, a piston is fixed relative to a housing to form a chamber between the housing and the piston. The chamber is filled with a pressurized fluid and the piston is released to allow the pressurized fluid move the piston relative to the housing and generate the sound wave.

Abstract: A system for sonically probing a seabed comprises at least one row of transducers that each can produce a sonic beam, and a corresponding row of sonic detectors. Each transducer is independently energized to produce a narrow sonic beam, with resulting seabed or subsea echoes being detected to produce one pixel of a display formed by an X-Y array of pixels, before a next transducer is energized and its echoes are detected to produce another pixel of the display. When the system detects a large change in echo amplitude at adjacent seabed locations, then scanning at those locations is accentuated by analysis and by additional sonificiation at different frequencies. The transducers are closely spaced, at a center-to-center distance of typically about 3.5 cm, to provide good horizontal resolution. Each transducer is energized to produce a sonic pulse which, dependent on the application, has a carrier frequency of 0.25 MHz.

Abstract: Apparatus for providing a temperature profile of the ocean for a towed so array. A towing cable for the array comprises a central cable and a protective outer jacket. Thermistors are disposed at spaced positions along the outer jacket and connect to conductors embedded in the protective outer jacket. The conductors terminate onboard ship to provide continuous signals representing temperatures at various ocean depths.