Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
  • G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
  • G01V1/16—Receiving elements for seismic signals; Arrangements or adaptations of receiving elements
  • G01V1/20—Arrangements of receiving elements, e.g. geophone pattern
  • G01V1/201—Constructional details of seismic cables, e.g. streamers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
  • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
  • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
  • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
  • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
  • B06B1/0607—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements
  • B06B1/0622—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements on one surface
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
  • G01S3/80—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using ultrasonic, sonic or infrasonic waves
  • G01S3/802—Systems for determining direction or deviation from predetermined direction
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
  • G01S7/521—Constructional features
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/18—Methods or devices for transmitting, conducting or directing sound
  • G10K11/26—Sound-focusing or directing, e.g. scanning
  • G10K11/34—Sound-focusing or directing, e.g. scanning using electrical steering of transducer arrays, e.g. beam steering
  • G10K11/341—Circuits therefor
  • G10K11/346—Circuits therefor using phase variation

Definitions

• the present invention relates to the production of a towed passive sonar with multibeam antenna.
• This passive device is particularly intended for anti-submarine warfare.
• the invention also relates to the manufacture of such an antenna.
• antennas of linear structure also called "flutes”. These devices are commonly used in the field of underwater seismic prospecting or in the fight against submarines. They are, for example, in the form of linear assemblies of hydrophone type sensors, thus reproducing a chain structure.
• the hydrophones are spaced apart by a distance substantially equal to half the wavelength corresponding to the center frequency of the frequency band being listened to.
• the device according to the invention relates to a towed passive sonar comprising at least one multibeam antenna, an electrotractor cable and signal processing means.
• the multibeam antenna of the device according to the invention notably comprises polyurethane plates in which are hydrophones arranged in arrays. This antenna is towed by a surface vessel, by means of an electrotractor cable which tows it and makes the electrical connection between the hydrophones and the equipment located on the carrier ship.
• the attachment of the antenna to the cable makes the antenna mechanically integral with the cable, which advantageously simplifies the electrical connection of the antenna to the cable, this connection being able to be carried out without using a complex connection device, of the rotating collector type for example.
• the antenna according to the invention is formed of an axial element on which are arranged elements comprising acoustic sensors, for example hydrophones, in the form of plates. The signals received from each sensor are transmitted separately to the equipment located on the surface building.
• the plates advantageously arranged around a central axis thus form a regular volume structure. This structure reduces the size of the antenna.
• the antenna thus has the advantage of having substantially smaller dimensions than a "flute" type antenna with comparable performance.
• the plates are generally of planar shape, which facilitates the progression of the antenna in the medium.
• any other shape that does not alter the progression of the antenna in the medium is possible, for example a cylindrical shape whose generatrices are parallel to the central axis.
• the antenna according to the invention furthermore comprises means making it possible to determine its attitude with respect to the horizontal and to the axis of progression of the ship. These means also make it possible to detect the rotational movements of the antenna around the central axis and to determine the value of the angle of rotation.
• the device according to the invention advantageously associates with the antenna means for processing the received signals.
• These means apply an adaptive processing to the signals received by each of the hydrophones which, for example, performs the formation of listening beams intended to ensure an omnidirectional detection capacity.
• the production method according to the invention advantageously makes it possible to obtain antennas with performances comparable to those of "flute" type antennas for a substantially smaller mass and size. It also makes it possible to overcome the effects of the rotation of the antenna around its axis and to know precisely the directions of reception of the signals. It also has the advantage of being inexpensive to produce.
• FIG. 1 a schematic representation in a first embodiment, of an antenna manufactured according to the method of the invention.
• FIG. 2 a cross-sectional view, according to a first embodiment, of an antenna according to the invention,
• FIG. 3 a view in longitudinal section according to the embodiment of FIG. 2, of an antenna according to the invention
• FIG. 4 a second detailed view in cross section according to the embodiment of FIG. 2, of an antenna according to the invention
• Figure 5 a longitudinal sectional view of the mechanical interface between the antenna and the electrotractor cable.
• FIG. 6 a detailed view in transverse section of the mechanical interface between the antenna and the electrotractor cable.
• FIG. 7 the illustration of a device allowing a simple implementation of the device according to the invention.
• FIG 8 the illustration of a particular embodiment of the antenna fitted to the device according to the invention.
• FIG. 9 The illustration of an alternative embodiment of the antenna according to the invention, relating to the maintenance of the plates.
• Figure 1 shows schematically the main structure of the antenna according to the invention, in a first embodiment.
• the modular multibeam antenna 10 appears to have an axial element 11 around which elements 12, 13 are regularly positioned in which hydrophones are included 16.
• the axial element has an extension 14 intended in particular to receive a mechanical and electrical connection interface making it possible to connect the antenna to an electrotractor cable which performs the functions of electrical connection cable and towing cable.
• An example of interface is shown in Figure 5.
• the axial element 1 1 follows a substantially horizontal trajectory in the direction of movement of the towing vessel.
• the elements 12 and 13 are for example produced according to a known technique, by molding in a material of the polyurethane type. Each plate is produced by placing the hydrophones on a plastic mesh, the hydrophone connection wires being, for example, attached to the mesh.
• the assembly is placed in a mold which lets out the ends of the connection wires by one of its sides.
• the mold is then filled with polyurethane by casting.
• the polyurethane used advantageously has a hardness of the order of 60 shores A, which makes it possible to provide the entire structure with sufficient mechanical rigidity.
• a type of polyurethane is described in French patent 2,069,875.
• the hydrophones 16 used are preferably hydrophones of tubular shape comprising a ceramic chip associated with a preamplifier circuit.
• Tri-blade sensors can also be used, made of polyvinylidene fluoride (PVDF).
• the distribution of the hydrophones in a plate can be a regular distribution, the hydrophones being for example regularly distributed over rows and columns, the spacing between two neighboring hydrophones being substantially equal to the half-length of the wave corresponding to the frequency center of the listening band.
• the arrangement of the hydrophones is carried out by taking account of the different sub-bands.
• the antenna of the device according to the invention makes it possible to obtain a volume distribution of the hydrophones.
• this volume structure advantageously makes it possible to form, using appropriate processing means of the signals received from each sensor, listening beams 15, or reception channels, having the geometry desired and can be oriented in all directions of space. Examples of reception channels are shown in Figure 1 in a conical shape. These beams have a width such that they overlap at least 3dB of the maximum gain.
• the processing means making it possible to carry out the adaptive formation of the beams from the signals received by distributed sensors are known elsewhere and are not described here. It is simply recalled that these means consist in applying different delay laws to the signals received simultaneously by all the hydrophones 16. Each delay law makes it possible to form a listening beam 15 in a given direction. It is thus possible to simultaneously form, from the signals received by the set of sensors, a set of beams of given width covering the whole of the space to be listened to with a given resolution.
• the antenna of the device also includes a sensor, not shown in the figure, making it possible to know at any time its orientation in the medium in which it moves and in particular to follow its rotational movements around its axial element 1 1.
• the orientation of the device being thus known, the antenna advantageously does not need to be stabilized in position or in rotation. This property makes possible a fixed connection of the cable to the antenna, without an articulation device.
• the variations in orientation of the antenna that may occur are recorded by the sensor, transmitted to the surface building which tows the antenna and taken into account by the signal processing means to correct the direction of the beams formed.
• a sensor is a known device, an example of which is in particular described in the French patent application published under the number 2.808.084.
• FIG. 2 shows a view in cross section of the antenna shown schematically in FIG. 1.
• the antenna comprises four elements. Two horizontal elements are produced on the same horizontal plate 210 and the vertical elements are produced on two separate vertical plates 211. These plates are made of polyurethane as described above.
• the hydrophones 16 are for example distributed in lines parallel to the central axis and in columns perpendicular to this axis.
• the connection wires 23 of the hydrophones of the same column are directed towards the central axis of the plate where they are grouped step by step in a strand 22 with the connection wires of the hydrophones of the other columns.
• the hydrophones inserted in the plates 211 and 210 are distributed in rows and columns.
• the connection wires 23 of the hydrophones of the same column are directed towards an external edge so as to form an external strand 24.
• the strand thus formed travels along the central axis until it leads to the end of the plate located on the side of the extension 14 intended to receive the connection interface.
• the central element 1 1 shown diagrammatically in FIG. 1 comprises two profiled elements 21 of identical shape and of a length substantially equal to that of the long side of the plates. These elements are made of a material such as aluminum, for example, or else of a composite material of the glass fiber type.
• Each profiled element has along its length two grooves 25 and 26 which communicate through openings 27 positioned opposite the hydrophone columns and intended for the passage of connection cables which exit from the plates 211 from the side.
• the antenna is assembled by fixing the profiled elements on the horizontal plate 210 and fixing the plates 211 in the grooves 25 of the profiled elements.
• the fasteners are also distributed over the entire length of the plates 211 and of the plate 210.
• the tightness of the assemblies of the plates and the profiled elements can for example be supplemented by the installation of linear seals 28 housed in grooves made on the profiled elements at the contact zones.
• the connection wires 23 of the hydrophones included in the vertical plates 211 pass through the elements profiled by the openings 27 and are joined together in strands 24 which run in the grooves 26 up to the end comprising the extension 14.
• FIG. 3 presents a view in a longitudinal section of the antenna shown schematically in FIG. 1.
• This figure illustrates in particular a possible method of assembly of the profiled elements 21 and of the plates 211 and 210.
• This method of assembly presented as an example is of course not the only one possible.
• the assembly is carried out here by way of through holes 31 through which pass bolts which also seal by tightening the linear joints 28 between the face of the profiled element and the plate on which it is fixed.
• elements 32 of substantially triangular section can for example be fixed on the edges of the plates 211 and 210 corresponding to the short sides, so as to reduce the thickness of these edges.
• the elements 32 are for example assembled to the plates by means of dowels 33 and glued.
• An element 32 is shown in Figure 3 which also shows a top view 34 of the same element.
• FIG. 4 presents a more detailed view according to a cross section of a possible structure for assembling the profiled elements 21 on the plates 211 and 210 described in the preceding paragraph.
• bolts 41 not shown in Figure 3, whose rods pass through the holes 31 provided for assembly.
• the assembly and sealing are carried out by tightening the bolts.
• connection wires of the hydrophones are not shown in the figure.
• FIG. 5 presents a partial view in longitudinal section of the structure of the antenna according to the invention, in its part in connection with the electrotractor cable. It illustrates an example of an electrical and mechanical interface with the electrotractor cable.
• the interface comprises a solid mechanical part 51 secured to the profiled elements 21. It also includes a mechanical part 53, one end of which is fixed to the part 51 and the other end of which is connected to the electrotractor cable 57.
• the mechanical part 51 is in the form of a cylinder of length L which has a recess 52 in its center allowing the passage of the strands 22 and 24.
• the mounting of the mechanical part 51 on the extension 14 of the antenna is carried out in the most appropriate manner. In the case of metallic profiled elements, the mounting can for example be carried out by welding.
• the mechanical part 53 is a massive part which in particular ensures the recovery of the forces exerted by the traction cable. It is in the form of a cylinder having a conical end extended by a cylindrical part 54. Its end fixed to the mechanical part 51 has a cylindrical recess 55 allowing the fixing. This recess is extended by another recess 56 of conical shape, allowing the bundling and passage of the strands 22 and 24.
• the cylindrical part 54 of the part 53 is in particular intended to ensure the electrical and mechanical junction with the electrotractor cable 57.
• This junction is produced according to known techniques used in particular for the connection of "flute" type antennas to the towing cable.
• the assembly of parts 51 and 53 can for example be carried out by screwing. In this case, a threading of the external face of the part 51 as well as a threading of the wall of the recess 55 are made.
• FIG. 6 represents a cross-sectional view of the interface produced by the mechanical parts 51 and 53. This figure puts in particular, the way in which the two parts are assembled, the part 51 being housed in the recess made at the end of the part 53. FIG. 6 also shows the path of the strands 22 and 24 inside the recess in room 51.
• FIG. 7 presents a set of means making it possible to easily put into the sea and recover the antenna of the device according to the invention.
• These means comprise a winch 71 on which the electrotractor cable 30 is wound and an inclined cradle 72 inside which the cable passes.
• the cradle serves as a passage for the electrotractor cable, while when the antenna is stored on board, it is housed in the cradle.
• the cradle may include fixings not shown in the figure, making it possible, for example, to keep the antenna in the cradle even if the sea is heavy.
• the cradle can advantageously be mounted on a ball joint 73.
• the antenna being towed by the cable during the winding of the latter on the winch, its positioning in the cradle is automatic and does not require human intervention.
• the implementation of the device according to the invention advantageously requires less significant means than those necessary for the implementation of sonars such as sonars with linear antennas known elsewhere.
• the linear antennas are presented as tubular structures of great length, having a more reduced flexibility than an electric cable and which therefore require to have available for their storage a large winch allowing a loose winding.
• only the electrotractor cable is wound. This cable can be wound more tightly and advantageously requires a winch of smaller dimensions.
• the antenna having a compact structure its storage is advantageously simpler than that of a tubular antenna.
• the device according to the invention has the advantage of responding in particular to the implementation problems raised by the size and weight of the linear antennas used for towed sonar.
• the reduced size of the antenna makes the device according to the invention naturally insensitive to the maneuvers carried out by the carrier ship, which tend to reduce the performance of the linear antennas.
• its functional structure in a network of hydrophones advantageously makes it possible to obtain an antenna having substantially the same performance in all directions of the listening space and to eliminate the drawback constituted by the right / left ambiguity presented. by linear antennas.
• the antenna thus produced also has a gain comparable to a tri-flute type device while having a much smaller footprint.
• the method implemented for the manufacture of the antenna advantageously makes it possible to obtain a device having a cost of production substantially lower than that of a sonar equipped with a linear antenna.
• the plates 12 comprise 32 hydrophones distributed in two lines of 16 hydrophones spaced by a distance substantially equal to 0.125m.
• the plate 210 comprises 80 hydrophones distributed in two groups of 32 hydrophones placed on either side of the central axis of the plate, each group being divided into two lines of 16 hydrophones to which are added the 16 hydrophones of the central axis.
• the thickness of the plates is moreover conditioned by the size of the hydrophones and by the need to ensure sufficient rigidity at the antenna.
• Hydrophones for example of cylindrical shape, adapted to a central listening frequency substantially equal to 6 kHz have dimensions substantially equal to 10 mm in diameter and 15 mm in height.
• Such an antenna has the advantage of offering a space and a mass allowing an easy storage and an implementation in particular with regard to the putting at sea.
• FIGS. 1 to 6 The antenna of the device according to the invention is illustrated through FIGS. 1 to 6 in a particular embodiment.
• This embodiment is of course not exclusive and can obviously be subject to variations, insofar as the essential characteristics of the invention remain unchanged.
• FIGS 8 to 10 show, by way of example, other possible embodiments.
• FIG. 8 illustrates an embodiment which is a variant of the mode described above.
• the advantage of this embodiment lies in the fact that the antenna according to the invention here comprises only three elements 81 spaced angularly by 120 ° and fixed on a central element 82.
• the plates constituting the elements 81 are produced according to a process substantially identical to that used to produce the plates 211 or 210 of the previous embodiment. They notably include hydrophones 16 arranged in rows and columns.
• the central element 82 is a profiled element of hexagonal section, having in its center a cylindrical channel 83.
• the central element has on three of its faces grooves 84 in which the plates 81 fit together by their longest side.
• the fixing of the plates to the profiled element is also completed by fixing brackets 85 integral with the plates and fixed to the profiled element by means of screws 86.
• connection wires 23 of the hydrophones of the same column pass to the central channel 83 where they are grouped.
• the connection wires run through the channel in a single bundle 88, up to the end of the antenna which interfaces with the electrotractor cable.
• the embodiment illustrated in Figure 8 can also call a close variant not shown here, in which the antenna has four plates perpendicular to each other and fixed on a profiled element of octagonal section.
• FIG. 9 illustrates a variant structure of the antenna according to the invention in the embodiment illustrated by FIGS. 1 to 6.
• a reinforcing element of the main structure is produced by means of elements in rings 91 placed near the ends of the structure and encircling the polyurethane plates.
• These elements can be made of a material such as aluminum or a composite ring material. They are assembled to the main structure by means of the plates to which they can for example be screwed or glued, depending on the material of which they are made.
• the rings 91 are assembled to the polyurethane plates 21 1 and 210 by a set of screws 92.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Remote Sensing (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Life Sciences & Earth Sciences (AREA)
• Acoustics & Sound (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Environmental & Geological Engineering (AREA)
• Geophysics (AREA)
• Multimedia (AREA)
• Computer Networks & Wireless Communication (AREA)
• Mechanical Engineering (AREA)
• Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
• Transducers For Ultrasonic Waves (AREA)

Applications Claiming Priority (3)

Publications (1)

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Family Cites Families (7)

• 2003
  • 2003-02-14 FR FR0301831A patent/FR2851339B1/fr not_active Expired - Fee Related
• 2004
  • 2004-02-13 EP EP04710893A patent/EP1592980A1/fr not_active Withdrawn
  • 2004-02-13 WO PCT/FR2004/000335 patent/WO2004077089A1/fr active Application Filing
• 2005
  • 2005-09-14 NO NO20054256A patent/NO20054256L/no not_active Application Discontinuation

Non-Patent Citations (1)

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