Abstract:
L'invention concerne les procédés de traitement des signaux d'une antenne linéaire remorquée comprenant n (de préférence 3) sous-antennes parallèles formant des multiplets d'hydrophone. On mesure (110) l'angle de roulis des multiplets pour synthétiser (101 ) des sous-antennes linéaires stabilisées. On forme ensuite (102) M v voies gisement pour chaque canal doppler avec chaque sous-antenne, et on forme enfin ( 104 ) 2 voies droite-gauche adaptatives à partir de ces sous-antennes. Elle permet de lever l'ambiguité droite-gauche avec de meilleures performances en détection et pour des antennes longues.
Abstract:
L'invention concerne les systèmes de détection sous-marine à basse fréquence comprenant une antenne linéaire remorquée (12, 13). Elle consiste à réaliser les transducteurs de l'antenne d'émission (12) sous la forme de flextenseurs de type cylindrique (20) et à former des vois directives d'émission couvrant tout l'espace. Elle permet d'alléger l'ensemble et de faciliter la mise en oeuvre à la mer, qui devient automatisable.
Abstract:
The invention concerns birds enabling to control navigation of a towed linear acoustic antenna. It consists in equipping said bird with a pair of horizontal wings (117, 118) and a pair of vertical wings (119, 120). Said wings are maintained horizontal and vertical by pendular oscillation of the bird about the antenna (105) whereon it is fixed, thereby uncoupling the action of the horizontal wings, which affect only immersion, and the vertical wings which bear only on the lateral misalignment. Thus the power consumption of the bird is reduced enabling thereby its being powered by internal batteries (10() and its being mounted on existing antennae.
Abstract:
The invention concerns low-noise towed acoustic linear antennae for seismic exploration. It consists in perforating said antenna sheath (101) with holes (102) allowing sea water to penetrate inside the antenna. The hydrophones (104) are insulated by being enclosed in polyurethane cases (105) filled with oil or gel (107). The buoyancy is ensured by lightening the sheath with hollow inclusions formed by microbeads. The invention enables to reduce by 15 dB the noise level at the output of the hydrophones.
Abstract:
A connection system for connecting external devices to specified locations on a marine seismic streamer. Inner collars are clamped to the cable at specified locations along its length. Each inner collar forms a circular race encircling the cable. A cuff attached to an external device is in the form of a C-shaped cylindrical ring with a circular inner surface. A throat is formed in the ring by a gap, which extends the full length of the cuff across the ends of the C. The spacing between the ends of the C across the throat defines the width of the gap, which is slightly larger than the diameter of the cable so that the cuff can be slipped over the cable through the throat, and which is smaller than the diameter of the circular race so that, when the cuff is slid into position on the race, the cuff cannot be removed radially.
Abstract:
A seismic streamer (10) comprises a substantially solid core (24) having many of the main components of the streamer, namely hydrophones (30), electronic modules (34) for digitising the outputs of the hydrophones, the main optical and electrical conductor bundles (36) and Kevlar strength members (32), embedded in it. The core (24) also contains a large number of foam buoyancy elements (38). An outer skin (26) surrounds the core (24), defining an annular gap (28) around the core, and this annular gap is filled with open-celled polyurethane foam saturated with kerosene. The capsules (40) containing the hydrophones (30) communicate with the annular gap (28) around the core (24), so that the kerosene can enter the capsules (40), each of which contains an open-celled polyurethane foam sheath (42) to cushion the hydrophone (30). In an alternative construction, made possible by using the buoyancy elements (38) in the core (28) to render the core (28) approximately neutrally buoyant in water, the outer skin (26) and the polyurethane foam are omitted, and the core (24) is used on its own as a solid streamer.
Abstract:
An automated streamer production line for producing 100 metre long streamer sections comprises an elongate bench provided with tensioning devices for supporting the Kevlar rope harness of the streamer under tension. At one end of the bench, an automatic feed device automatically feeds groups of components, typically spacers, foam sections and hydrophones, onto the Kevlar ropes, via an in-feed "lock" or "sluice" defined by two spaced apart clamping devices. The clamping devices are opened sequentially, so as to maintain the Kevlar ropes continuously under tension as the components are fed onto them. A shuttle then moves the components along the Kevlar ropes to the desired position, and at least some of the components, typically the spacers, are automatically glued to the ropes.
Abstract:
A flexible interlink (10) for joining a first sensor of the type that includes a cylindrical mandrel for mounting a common optical fiber to a second sensor of a hydrophone that includes a cylindrical mandrel for mounting said fiber. The interlink includes an integral molded body of flexible material. Enlarged diameter ends (16, 18) are joined to the link by outwardly-tapered transition members. Resilient metal washers (20) are fixed to the ends for locking onto the sensor. The washer includes radial elements that abut corresponding radial elements of the end. The radial elements of the washer are outwardly inclined, of greater length than the corresponding radial elements of the end and exceed the inner diameter of the sensor from tip to tip.
Abstract:
A system for communicating with and powering sensors and cable control and monitoring devices deployed at individual locations along an instrumented underwater cable used in offshore seismic prospecting or scientific, and/or military underwater cable or other applications. The system includes a unique underwater cable architecture, coupler design, and electrical device architecture to improve the reliability of the underwater cable and to allow the electrical devices to receive operational power from the underwater cable.
Abstract:
A sensor cable (1) comprises an inner core (2) including an array of sensors (3), conductors (7) which are connectible between the sensors and remote receiving, monitoring and/or processing apparatus, and an outer sheath (12), in which the conductors are connected to a conductor harness (9) extending along the cable between the inner core and the outer sheath. For use on the sea-bed, the conductor harness and the outer sheath form concentric layers around the core, which may be formed from a castable polyurethane. For use in towing in the water, the core may be formed from polyurethane containing microballoons and the outer sheath may be filled with water or other aqueous medium, conveniently sea-water.