AU702908B2

AU702908B2 - Acoustic sensor modules

Info

Publication number: AU702908B2
Application number: AU21845/95A
Authority: AU
Inventors: Allan Lloyd Carpenter
Original assignee: Thales Underwater Systems Pty Ltd
Current assignee: Thales Underwater Systems Pty Ltd
Priority date: 1992-04-09
Filing date: 1995-06-22
Publication date: 1999-03-11
Anticipated expiration: 2012-04-09
Also published as: AU2184595A

Description

-2an elongate, hollow, generally cylindrical, liquid-tight jacket having two open ends; a pair of end connectors attached to, and sealing, the open ends of the jacket; an open cell plastics foam core having voids therein, and extending along the interior of the jacket; a plurality of acoustic sensors located within the foam core; power and data cables connected to the acoustic sensors, and extending along the interior of the jacket; a low density liquid substantially filling the voids within the foam of the foam core; and a plurality of strength rings spaced apart along the length of the jacket for strengthening the jacket, each strength ring being disposed within the jacket and arranged coaxially with the central longitudinal axis thereof, and extending around the power and data cables so as to protect the power and data cables against crushing.

Acoustic sensor modules, which can be up to several kilometres long, are often wound onto winches on vessels, and can therefore be subjected to considerable crushing forces. Placement of the power and data cables inside the strength rings ensures that they are protected against damage during such winching.

Preferably, a layer of paper is wrapped around the outside of the power and data cables, and is located between the power and data cables and the strength rings.

Additionally or alternatively, a layer of braided polypropylene can be wrapped around the power and data cables, between the power and data cables and the strength rings.

Advantageously, an inner layer of paper is wrapped around the foam core, and is disposed between the foam core and a substantial portion of the power and data cables.

Preferably, a plurality of longitudinal strength members extend between the end connectors, at least some of the longitudinal strength members being embedded within S. the material of the jacket.

The acoustic sensor module can further comprise electronics packages associated with the acoustic sensors, and located within the foam core.

In that case, the acoustic sensors and electronics packages are conveniently connected to the data cables by connecting leads of small diameter, which pass radially outwards through the foam core to the data cables.

Preferably, at least one of the end connectors is provided with a valve for allowing the low density liquid to pass into the module.

Desirably, the jacket of the module is formed from vibration damping material.

According to a second aspect of the invention there is provided an acoustic sensor module for towing underwater behind a vessel in order to obtain acoustic information, Sthe acoustic sensor module comprising: [N:\libe]OOO96:MXL -3an elongate, hollow, generally cylindrical, jacket having two sealable ends; a pair of end connectors attached to, and sealing, the sealable ends of the jacket so as to form a liquid-tight enclosure; a foam core having liquid fillable voids therein, and extending along the interior of the jacket, said foam core having a low density liquid contained in the voids therein, for adjusting the buoyancy of said module; a plurality of acoustic sensors located within the enclosure; power and data cables connected to the acoustic sensors, and extending along the interior of the jacket; and a plurality of strength rings spaced apart along the length of the jacket for strengthening the jacket, each strength ring being arranged coaxially with the longitudinal axis of the jacket, and extending around the power and data cables so as to protect the power and data cables against crushing.

Generally, the acoustic sensors are located within the foam core.

The invention also provides an acoustic array comprising a plurality of end-to-end connected acoustic sensor modules, each as described above.

Preferably, the end connectors are provided with valves which open when the end connectors of adjacent acoustic sensor modules are connected together, to allow the low density fluid to pass in and out of the acoustic array and thus allow the buoyancy of the 20 acoustic array to be controlled.

The acoustic array can be provided with an outer jacket, extending over a number of acoustic sensor modules, and being arranged outside of the jackets of the acoustic sensor modules to provide a further layer of protection for the acoustic array.

Conveniently, the outer jacket is applied as a co-extrusion simultaneously with extrusion of the jacket of the module.

Alternatively, the outer jacket can be applied separately in a second pass through an extruder.

The invention also provides an acoustic array assembly, comprising an acoustic array as described above, and a feeder tube for connection between a towing vessel and 30 the acoustic array, and through which low density liquid can be introduced into, or extracted from, the acoustic array to provide fine control of the buoyancy of the S" acoustic array.

One embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawing, which schematically shows the structure of a portion of an acoustic sensor module.

The acoustic sensor module 2 comprises an extruded cylindrical jacket 4 within which are housed a number of acoustic sensors 6 and associated electronics packages 8.

The acoustic sensor module 2 is intended to form part of an acoustic array which is towed behind a vessel and used to gather acoustic information.

[N:\libe]OOO96:LHJ -4- The acoustic sensors 6 and the electronics packages 8 are embedded in an open cell plastics foam core 10, which substantially fills the interior of the jacket 4.

Although not shown in the drawings, the foam core 10 is made up of a number of foam segments, which fit together around the acoustic sensors 6 and electronics packages 8, thereby cushioning them against mechanical shock.

A number of polypropylene tapes 12 run longitudinally along the outside of the foam core 10, and provide the core of the sensor module 2 with greater rigidity for handling during manufacture.

Around the tapes 12 and the foam core 10 is wound an inner paper wrap layer 14.

Immediately outside the inner paper wrap layer 14, a number of power and data cables 16 extend longitudinally along the sensor module 2. The power and data cables 16 transmit and receive data to and from the electronics packages 8, and provide the electronics packages 8 with power. The power and data cables 16 can be made up of twisted pairs, coaxial cables, twin-ax cables and/or fibre optic cables. Any spaces between the power and data cables can be filled using one or more filler cables 18.

Around the power and data cables 16 is wound an outer paper wrap layer 20, and around the outer paper wrap layer 20 is wound a layer of braided polypropylene 22.

The inner and outer paper wrap layers 14 and 20 serve to hold the power and data cables 16 in position.

20 Strength rings 24 extend around, and are glued to, the braided polypropylene layer 22, and serve to increase the strength of the acoustic sensor module, and to protect the internal components, including the power and data cables 16, against crushing. The strength rings 24 are evenly spaced along the entire length of the acoustic sensor module 2.

Finally, the extruded jacket 4 extends around the strength rings 24 and the braided polypropylene layer 22, and provides the acoustic sensor module with a watertight seal. A number of braided strength cords 26 are co-extruded in the material of the jacket 4, and extend along the acoustic sensor module. As shown in the drawing, the cords 26 are grouped together into a number of separate groups.

The acoustic sensors 6 and electronics packages 8 are connected to each other, and to the power and data cables 16 by connecting leads 28, which extend between the various segments of the foam core S•A pair of end connectors (not shown) are connected to, and seal, the open ends of the jacket 4, and are provided with valves for allowing the module 2 to be filled with a low density liquid. The low density liquid can, for example, be a light paraffin or low molecular weight paraffin, such as one of those sold under the registered trade marks ISOPAR M and NORPAR 13. The low density liquid fills inter-linked voids within the material of the foam core 10, and by controlling the amount of liquid within the module 2 the buoyancy of the acoustic sensor module can be controlled. The end connectors [N:\libe]00096:LHJ allow a number of acoustic sensor modules to be connected together in a line to form an acoustic array. If required, the valves in the end connectors can be arranged so that they open when two adjacent end connectors are connected together. Such an arrangement allows the low density liquid to be passed into, or extracted from, the acoustic array, for example by means of a feeder tuber connected to a towing vessel, in order to control the buoyancy of the acoustic array.

The foregoing describes only one embodiment of the present invention, and modifications, obvious to those skilled in the art, can be made thereto without departing from the scope of the present invention.

9 ft ft [N:\libe]00096:LHJ The claims defining the invention are as follows: 1. An acoustic sensor module for towing underwater behind a vesel in order to obtain acoustic information, the acoustic sensor module comprising: an elongate, hollow, generally cylindrical, liquid-tight jacket having two open ends; a pair of end connectors attached to, and sealing, the open ends of the jacket; an open cell plastics foam core having voids therein, and extending along the interior of the jacket; a plurality of acoustic sensors located within the foam core; power and data cables connected to the acoustic sensors, and extending along the interior of the jacket; a low density liquid substantially filling the voids within the foam of the foam core; and a plurality of strength rings spaced apart along the length of the jacket for strengthening the jacket, each strength ring being disposed within the jacket and arranged coaxially with the central longitudinal axis thereof, and extending around the power and data cables so as to protect the power and data cables against crushing.

2. An acoustic sensor module as claimed in Claim 1, wherein a layer of paper is wrapped around the outside of the power and data cables, and is located between the power and data cables and the strength rings.

S3. An acoustic sensor module as claimed in Claim 1 or 2, wherein a layer of braided polypropylene is wrapped around the power and data cables, between Sthe power and data cables and the strength rings.

S4. An acoustic sensor module as claimed in any preceding claim, wherein S 25 an inner layer of paper is wrapped around the foam core, and is disposed between the foam core and a substantial portion of the power and data cables.

An acoustic sensor module as claimed in any preceding claim, wherein :a plurality of longitudinal strength members extend between the end connectors, at least some of the longitudinal strength members being embedded within the material of the jacket.

6. An acoustic sensor module as claimed in any preceding claim, which further comprises electronics packages associated with the acoustic sensors, and located within the foam core.

7. An acoustic sensor module as claimed in Claim 6, wherein the acoustic sensors and electronics packages are connected to the data cables by connecting leads of small diameter, which pass radially outwards through the foam core to the data cables.

IN:\IibeOOO96:MXL

Claims

8. An acoustic sensor module as claimed in any preceding claim, wherein at least one of the end connectors is provided with a valve for allowing the low density liquid to pass into the module.
9. An acoustic sensor module as claimed in any preceding claim, wherein the jacket of the module is formed from vibration damping material. An acoustic sensor module for towing underwater behind a vessel in order to obtain acoustic information, the acoustic sensor module comprising: an elongate, hollow, generally cylindrical, jacket having two sealable ends; a pair of end connectors attached to, and sealing, the sealable ends of the jacket so as to form a liquid-tight enclosure; a foam core having liquid fillable voids therein, and extending along the interior of the jacket, said foam core having a low density liquid contained in the voids therein, for adjusting the buoyancy of said module; a plurality of acoustic sensors located within the enclosure; power and data cables connected to the acoustic sensors, and extending along the interior of the jacket; and a plurality of strength rings spaced apart along the length of the jacket for strengthening the jacket, each strength ring being arranged coaxially with the longitudinal axis of the jacket, and extending around the power and data cables so as to 20 protect the power and data cables against crushing.
11. An acoustic sensor module as claimed in Claim 10, wherein, the *.*.*acoustic sensors are located within the foam core. *I 12. An acoustic array comprising a plurality of end-to-end connected acoustic sensor modules as claimed in any preceding claim.
13. An acoustic array as claimed in Claim 12, wherein the end connectors of the acoustic sensor modules are provided with valves which open when the end connectors of adjacent acoustic sensor modules in the acoustic array are connected together, to allow the low density fluid to pass in and out of the acoustic array and thus :allow the buoyancy of the acoustic array to be controlled. 30 14. An acoustic array as claimed in Claim 12 or 13, which is further provided with an outer jacket, the outer jacket extending over a number of acoustic sensor modules, and being arranged outside of the jackets of the acoustic sensor modules to provide a further layer of protection for the acoustic array. An acoustic array as claimed in Claim 14, wherein the outer jacket is applied as a co-extrusion simultaneously with extrusion of the jackets of the modules.
16. An acoustic array as claimed in Claim 14, wherein the outer jacket is applied separately in a second pass through an extruder. [N:\libe]OOO96:LHJ -8-
17. An acoustic array assembly, comprising an acoustic array as claimed in any one of claims 12 to 16, and a feeder tube for connection between a towing vessel and the acoustic array, and through which low density liquid can be introduced into, or extracted from, the acoustic array to provide fine control of the buoyancy of the acoustic array.
18. An acoustic sensor module substantially as hereinbefore described with reference to the accompanying drawings.
19. An acoustic array comprising an acoustic sensor module as claimed in Claim 18.
20. An acoustic array assembly, comprising an acoustic array as claimed in Claim 19. DATED this, Twentyfirst Day of June 1995 -,-oro narP Systems Pty Lt Patent Attorneys for the Applicant T RA4 SPRUSON FERGUSON SEC -o 113 J S *ft o* [N:\libe]OOO96:LHJ ACOUSTIC SENSOR MODULES Abstract An acoustic sensor module for towing underwater behind a vessel in order to obtain acoustic information, the acoustic sensor module comprises: An elongate, hollow, generally cylindrical, liquid-tight jacket having two open ends; a pair of end connectors attached to, and sealing, the open ends of the jacket an open cell plastics foam core (10) having voids therein, and extending along the interior of the jacket A plurality of acoustic sensors located within the foam core power and data cables (16) connected to the acoustic sensors and extending along the interior of the jacket a low density liquid substantially filling the voids within the foam of the foam core and a plurality of strength rings (24) spaced apart along the length of the jacket for strengthening the jacket each strength ring (24) being arranged coaxially with the central longitudinal axis of the jacket and extending around the power and data cables (16) so as to protect the power and data cables (16) against crushing. oo i o9 9e• 9 9 9 99** IN:\libe]00096:LHJ