Abstract: Described herein are methods and devices for underwater deployment of a structure. For example, the embodiments described herein are particularly focused on sonobuoys that are configured for autonomous deployment in an underwater environment. One embodiment provides a sonobuoy having a plurality of arms, which are in some embodiments telescopic. The sonobuoy is configured such that, upon deployment in an underwater environment, the arms extend and rotate from a collapsed storage configuration to an operative configuration. The rotation is brought about by way of tension in petal lines, which extend between an innermost telescopic segment of each arm and a central tether line intermediate the arms and a buoyancy device.

Abstract: A device (10) for sensing an acoustic signal is described. The device includes a flexible portion (14) including a laser active region (13) whose emitted wavelength varies according to a mechanical force acting on the flexible portion (14) and a flexible support member (24) operable to flex or bend according to the acoustic signal. The flexible portion (14) is coupled with the support member (24) so as to cause the flexible portion to flex or bend in accordance with the support member (24) thereby changing the emitted wavelength of the laser active region (13) of the flexible portion (14).

Abstract: A hydrophone (10) for immersion in a liquid body defining a depth-dependent static pressure and a dynamic pressure. The hydrophone (10) includes a pressure-bearing element (11) for exposure to the liquid body; a motion sensor (13) spaced apart from the pressure bearing element (11); and a dilatant coupling material (14) disposed intermediate the pressure-bearing element (11) and the motion sensor (13) so as to mechanically transmit movements substantially corresponding to the dynamic pressure from the pressure-bearing element (11) to the motion sensor (13). The dilatant coupling material (14) does not transmit movements to the motion sensor (13) that substantially correspond to the depth-dependent static pressure.

Abstract: A hydrophone (10) for immersion in a liquid body defining a pressure is disclosed The hydrophone (10) includes a sensor (11) for providing an electrical signal indicative of the pressure; and a transducer (12) electrically connected to the sensor (11). The transducer (12) acts upon a fiber optic cable (15) so as to convert the electrical signal into a corresponding optical output signal for transmission within the fiber optic cable (15). The liquid body defines a depth-dependent static pressure and a dynamic pressure and the sensor (11) provides an electrical signal having a first component indicative of the static pressure and a second component indicative of the dynamic pressure. A filter (16) is electrically connected to the sensor (11) so as to receive (the electrical signal, filter out the first component, and output to the transducer (12) a uttered electrical signal indicative of substantially only the second component.

Abstract: A hydrophone (10) for immersion in a liquid body defining a depth-dependent static pressure and a dynamic pressure. The hydrophone (10) includes a pressure-bearing element (11) for exposure to the liquid body; a motion sensor (13) spaced apart from the pressure bearing element (11); and a dilatant coupling material (14) disposed intermediate the pressure-bearing element (11) and the motion sensor (13) so as to mechanically transmit movements substantially corresponding to the dynamic pressure from the pressure-bearing element (11) to the motion sensor (13). The dilatant coupling material (14) does not transmit movements to the motion sensor (13) that substantially correspond to the depth-dependent static pressure.

Abstract: A device (10) for sensing an acoustic signal is described. The device includes a flexible portion (14) including a laser active region (13) whose emitted wavelength varies according to a mechanical force acting on the flexible portion (14) and a flexible support member (24) operable to flex or bend according to the acoustic signal. The flexible portion (14) is coupled with the support member (24) so as to cause the flexible portion to flex or bend in accordance with the support member (24) thereby changing the emitted wavelength of the laser active region (13) of the flexible portion (14).

Abstract: A hydrophone (10) for immersion in a liquid body defining a pressure is disclosed The hydrophone (10) includes a sensor (11) for providing an electrical signal indicative of the pressure; and a transducer (12) electrically connected to the sensor (11). The transducer (12) acts upon a fibre optic cable (15) so as to convert the electrical signal into a corresponding optical output signal for transmission within the fibre optic cable (15). The liquid body defines a depth-dependent static pressure and a dynamic pressure and the sensor (11) provides an electrical signal having a first component indicative of the static pressure and a second component indicative of the dynamic pressure. A filter (16) is electrically connected to the sensor (11) so as to receive (the electrical signal, filter out the first component, and output to the transducer (12) a uttered electrical signal indicative of substantially only the second component.

Abstract: The invention relates to a method of graphical entry for the mapping of signal processing applications, intended for a machine comprising passive resources and active resources. It comprises at least the following steps: a) presenting in a first screen zone an “Archi View” portraying in the form of icons the available active or passive resources of the architecture of the machine in respect of a given level Li and the relationships between the resources, in a global model and/or in a local model, b) constructing the signal processing application in a second screen zone forming an “Appli View”, by borrowing one or more icons representative of the resources of the “Archi View”, the 2 steps a) and b) are implemented in a hierarchical manner by using ever finer successive views of the architecture of the machine.

Abstract: An apparatus and method of sensing fluid flow are provided to measure fluid flow rates in production tubing, pipelines, open wells and tunnels. The proposed invention takes advantage of a sensor with processing means to interpret the fluid flow rate, the sensor being responsive to the mechanical perturbations of the sensor itself arising from the impingement of turbulent fluid flow on the sensor. In operation, the sensor is mounted in the fluid flow such that the fluid flows through an aperture in the sensor and/or around the outside surface of the sensor. The sensor of the invention bears definite advantage over known sensors and it is particularly suited to downhole oil and gas applications. Preferably, the invention employs fiber optic sensing techniques which are amenable to multiplexing a plurality of the sensors with long down leads. Such an arrangement is robust to withstand the high temperature and pressure environment.

Abstract: The invention relates to the methods for automatic placing of the tasks of an application in a signal-processing machine. It consists in determining a Table Distribution Operator (201), called TDO, by forming it with a chain of Elementary Operators (301), called EOs, which are separated by linking spaces (302). These elementary operators are 8 in number, 4 of which are direct and 4 of which are mirrors of the direct ones. It makes it possible to automate the hierarchization in the processing chain of a signal-processing machine operating with the method known by the name of “ARRAY-OL”.

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: A device that allows control of the navigation of a towed underwater device, such as a linear acoustic antenna. The device is equipped with a pair of horizontal wings and a pair of vertical wings. These wings are kept horizontal and vertical by pendular movement of the device about the antenna on which the device is fixed. The action of the horizontal wings, which influence only immersion, and of the vertical wings, which influence only the lateral offset, are thus decoupled. The power consumption of the device is reduced, thus allowing the device to be powered by internal batteries and allowing the device to be mounted on existing antennas.

Abstract: A connection for an underwater acoustics system connecting elements of an antenna embedded in a leaktight first block of the system and an electro-optical transmitter embedded in a separate leaktight second block of the system. The antenna is electrically connected to a first part of a divisible transformer, which is also arranged in the leaktight first block. The electro-optical transmitter (e.g., vertical cavity surface emitting laser) is electrically connected to a second part of the divisible transformer, which is also arranged in the leaktight second block. The first part and the second part are anatomically separated, as are the first and second blocks within which they are contained, but have cores that can magnetically communicate with one another. By this configuration, the divisible transformer can communicate signals from the antenna to the electro-optical transmitter without compromising the leaktightness of the first or second blocks, thereby protecting the components.

Abstract: An underwater acoustic transducer configured to emit a low-frequency broadband acoustic signal. The underwater acoustic transducer includes a cap in the form of a cylinder closed on one side and open on the other side. A piezoelectric plate operating in flexion is fixed on the base of the cylinder outside the cylinder. The inside cavity defined by the cylinder is open freely toward the outside medium in which the acoustic waves are to be emitted. For identical dimensions, the underwater acoustic transducer makes it possible to decrease a central frequency of emission and to increase bandwidth.

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: An apparatus and method of sensing fluid flow are provided to measure fluid flow rates in production tubing, pipelines, open wells and tunnels. The proposed invention takes advantage of a sensor with processing means to interpret the fluid flow rate, the sensor being responsive to the mechanical perturbations of the sensor itself arising from the impingement of turbulent fluid flow on the sensor. In operation, the sensor is mounted in the fluid flow such that the fluid flows through an aperture in the sensor and/or around the outside surface of the sensor. The sensor of the invention bears definite advantage over known sensors and it is particularly suited to downhole oil and gas applications. Preferably, the invention employs fibre optic sensing techniques which are amenable to multiplexing a plurality of the sensors with long down leads. Such an arrangement is robust to withstand the high temperature and pressure environment.

Abstract: A method of determining the bearing of a source of a sonar signal comprising determining the phase of a cyclic variation of the output signal of a sonar detector having a directional characteristic which occurs as the orientation of the detector, and hence its characteristic, is rotated. In a preferred method the sonar detector output is spectrum analysed at each of a plurality of different orientations of the detector to provide for each orientation a signal representative of the amplitude of a component of the signal produced by the source of a chosen frequency. The signals so obtained are then arranged to form a time series of samples of said component as the orientation of the detector is rotated at a predetermined frequency and the time series used to analyse the spectrum of the signal defined by the time series and thereby determine the phase of the sinusoidal component of the signal defined by the time series at the predetermined frequency. Apparatus for carrying out the method is also disclosed.

Abstract: This invention concerns a transducer comprising a layer of active material and a backing plate (110). The backing plate (110) has first and second major surfaces. A layer (111) of active material is affixed to the first surface. The transducer also includes a region adjacent to the second major surface into which region the backing plate (110) can be deflected. The region is substantially isolated from any external pressure incident on the layer of active material. Moreover, the backing plate (110) and/or layer of active material (111) is of a non-uniform thickness. Preferably, the backing plate (110) is thicker at a central region thereof than at an edge region thereof.