Ex. PGS 1059
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`EX. PGS 1059
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`
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`

`
`PCT
`WORLD INTELLECfUAL PROPERTY ORGANIZATION
`International Bureau
`INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`WO 97n1394
`
`(11) International Publication Number:
`
`(51) International Patent Classification 6 :
`GOlV 1138, 1120
`
`A2
`
`(43) International Publication Date:
`
`27 March 1997 (27.03.97)
`
`(21) International Application Number:
`
`PCf/US96/15128
`
`(22) International Filing Date:
`
`20 September 1996 (20.09.96)
`
`(81) Designated States: AU, CA, NO, SG, US, European patent
`(AT, BE, CH, DE, DK, ES, Fl, FR, GB, GR, IE, IT, LU,
`MC, NL, PT, SE).
`
`Published
`Without international search report and to be republished
`upon receipt of that report.
`
`(30) Priority Data:
`60/004,203
`60/004,209
`601005,500
`60/004,493
`60/004,494
`
`22 September 1995 (22.09.95)
`22 September 1995 (22.09.95)
`22 September 1995 (22.09.95)
`22 September 1995 (22.09.95)
`22 September 1995 (22.09.95)
`
`US
`US
`us
`us
`us
`
`(71) Applicant (for all designated States except US):
`THE
`LAITRAM CORPORATION [US/US]; 220 Laitram Lane,
`Harahan, LA 70123 (US).
`
`(72) Inventor; and
`(75) Inventor/Applicant (for US only): ROUQUETI'E, Robert, E.
`[US/US]; 633 Meursault Drive, Kenner, LA 70065 (US).
`
`(74) Agents: HUNT, Gregory, A. et al.; Leydig, Voit & Mayer,
`Suite 300, 700 Thirteenth Street, N.W., Washington, DC
`20005 (US).
`
`(54) Title: ELEC1RICAL POWER DISTRIBUTION AND COMMUNICATION SYSTEM FOR AN UNDERWATER CABLE
`
`(57) 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.
`
`Ex. PGS 1059
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`

`
`FOR THE PURPOSES OF INFORMATION ONLY
`
`Codes used to identify States party to the Per on the front pages of pamphlets publishing international
`applications under the Per.
`
`AM
`AT
`AU
`BB
`BE
`BF
`BG
`BJ
`BR
`BY
`CA
`CF
`CG
`CH
`Cl
`CM
`CN
`cs
`cz
`DE
`DK
`EE
`ES
`Fl
`FR
`GA
`
`Armenia
`Austria
`Australia
`Barbados
`Belgium
`Burkina Faso
`Bulgaria
`Benin
`Brazil
`Belarus
`Canada
`Central African Republic
`Congo
`Switzerland
`COte d'lvoire
`Cameroon
`China
`Czechoslovakia
`Czech Republic
`Germany
`Denmark
`Estonia
`Spain
`Finland
`France
`Gabon
`
`GB
`GE
`GN
`GR
`HU
`IE
`IT
`JP
`KE
`KG
`KP
`
`KR
`KZ
`Ll
`LK
`LR
`LT
`LU
`LV
`MC
`MD
`MG
`ML
`MN
`MR
`
`United Kingdom
`Georgia
`Guinea
`Greece
`HWigary
`Ireland
`Italy
`Japan
`Kenya
`Kyrgystan
`Democratic People's Republic
`of Korea
`Republic of Korea
`Kazakhstan
`Liechtenstein
`Sri Lanka
`Liberia
`Lithuania
`Luxembourg
`Larvia
`Monaco
`Republic of Moldova
`Madagascar
`Mali
`Mongolia
`Mauritania
`
`MW
`MX
`NE
`NL
`NO
`NZ
`PL
`PT
`RO
`RU
`SD
`SE
`SG
`Sl
`SK
`SN
`sz
`TD
`TG
`TJ
`TT
`UA
`UG
`us
`uz
`VN
`
`Malawi
`Mexico
`Niger
`Netherlands
`Norway
`New Zealand
`Poland
`Portugal
`Romania
`Russian Federation
`Sudan
`Sweden
`Singapore
`Slovenia
`Slovakia
`Senegal
`Swaziland
`Chad
`Togo
`Tajikistan
`Trinidad and Tobago
`Ukraine
`Uganda
`United States of America
`Uzbekistan
`Viet Narn
`
`Ex. PGS 1059
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`

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`W097/11394
`
`PCTIUS96/15128
`
`ELECTRICAL POWER DISTRIBUTION AND COMMUNICATION
`
`SYSTEM FOR AN UNDERWATER CABLE
`
`This application claims the benefit of U.S. Provisional Application No. 60/004,203,
`
`filed 9/22/95, which is incorporated herein by reference; U.S. Provisional Application No.
`60/004,209, filed 9/22/95, which is incorporated herein by reference; U.S. Provisional
`
`5
`
`Application No. 60/005,500, filed 9/22/95, which is incorporated herein by reference;
`
`U.S. Provisional Application No. 60/004,493, filed 9/22/95, which is incorporated herein
`
`by reference; and U.S. Provisional Application No. 60/004,494, filed 9/22/95, which is
`
`incorporated herein by reference.
`
`10
`
`Field of the Invention
`
`The invention relates to underwater cable assemblies and, more particularly, to
`
`apparatuses for powering and communicating with and powering electrical devices, such
`
`as sensors and cable-control devices, deployed at spaced locations along an instrumented
`
`underwater cable, such as a towed seismic streamer cable used in offshore seismic
`
`15
`
`prospecting or other applications.
`
`Background of the Invention
`
`Towed seismic streamer cable assemblies typically include a plurality of spaced
`
`electrical devices selectively disposed therealong. Where the electrical devices are
`connected around an exterior of the towed seismic streamer cable, they are commonly
`referred to as wet units.
`In many applications, the wet units are inductively coupled to
`
`20
`
`data communication lines within the seismic streamer.
`
`One or more of the seismic streamer cable assemblies may be towed by a survey
`
`vessel. The wet units communicate with dry-end electronics disposed, for example, on the
`survey vessel via one or more communication channels. Communication channels
`
`25
`
`between the wet units and dry-end electronics conventionally include either a single-ended
`or
`twisted-pair data communication
`line
`inductively coupled
`to
`the wet units.
`
`Electromagnetic coupling may be utilized to allow communication with the wet units
`
`without breaching the exterior sheath of the towed seismic streamer cable.
`
`Conventionally, each of the wet units receives operational power from a battery
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`1
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`~SHEEr (RULE21)
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`disposed within the wet unit. The use of batteries as a primary power source in the
`
`plurality of spaced electrical devices may be required in practical applications because of
`
`low coupling coefficients between the underwater cable and the wet units. However, the
`
`use of batteries as the primary power source is frequently undesirable since the batteries
`
`5 may require replacement every few weeks or months. Replacing the batteries typically
`
`involves removing the wet units as the seismic cable is retrieved onto rolls on the survey
`
`vessel. The wet units are then individually serviced by opening the wet unit and replacing
`
`and/or recharging the existing batteries. This battery maintenance process may be highly
`
`inefficient and results in unwanted down time. Further, when lithium batteries are used,
`
`10
`
`the cost of disposal and replacement of the batteries for a single vessel may exceed several
`
`hundred thousand dollars per year. Accordingly, conventional wet unit designs suffer
`
`from a number of problems.
`
`A major problem associated with eliminating batteries from the wet unit devices is
`
`the low coupling coefficient between the wet units and the underwater cable. Although
`
`15
`
`numerous attempts have been made to improve this coupling coefficient, these attempts
`
`have been less than satisfactory.
`
`U.S. Patent No. 4,912,684 to John T. Fowler describes a communication system
`
`which transmits both power and data signals along a one- or two-wire transmission line
`
`running the length of the underwater cable. The power signals may be used to charge
`
`20
`
`batteries in wet units such as cable-leveling birds attached along the cable. The power and
`
`data signals are inductively coupled between the transmission line and the wet units by
`
`means of coils connected to the transmission line at specific locations along the streamer
`
`and associated coils disposed within each bird. However, due to a number of technical
`
`difficulties, a seismic streamer cable assembly which transfers operational power from the
`
`25
`
`underwater cable directly to the wet units or to the wet units and in-streamer devices has
`
`not yet proven commercially practical.
`
`For example, conventional transmission lines are typically configured as continuous,
`
`unbroken transmission lines running the length of the streamer cable which has
`
`traditionally been about 6 km or less. Transmission line losses in transmission lines of
`
`30
`
`underwater streamer cables having a length longer than 6 km exacerbate the problems
`
`associated with powering the spaced electrical devices directly from the underwater
`
`streamer cable. Furthermore, data and/or power transmitted to electrical devices at the aft
`
`end of an underwater streamer cable are often severely attenuated. This problem may be
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`2
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`SUBSmuTE SIIEEr (RULE 21)
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`particularly acute where data lines are also utilized to transmit power. It has been found
`
`that transmission line losses and noise levels in such a system often make the system
`commercially impractical. Thus, communication with and power delivery to aft electrical
`
`devices may be difficult, particularly for ever increasing cable lengths. Much research
`
`5
`
`has been directed at solving this problem, but to date there has been little success.
`
`One approach is to resort to heavy gauge wire and increase the power level
`
`transmitted to the cable. However, this is typically unacceptable because additional
`
`weight may be added to the underwater cable and because higher power levels may
`
`interfere with the operations of the seismic equipment, such as
`
`the underwater
`
`10
`
`hydrophones.
`
`Another shortcoming of conventional power distribution and/or data communication
`
`systems is that the inductive circuits utilized to couple between the underwater cable and
`
`the wet units are required to be precisely tuned within narrow margins to ensure adequate
`
`coupling of power and data to or from the electrical devices. If an electrical device fails,
`
`15
`
`falls off, or is otherwise damaged or removed from the underwater cable, the associated
`
`coil on the transmission line may have an open secondary, detuning the tuned circuit.
`
`Often, the transmission line may be detuned to the point where reliable data and power
`
`transfer is compromised.
`In typical underwater sonar cables, it is difficult to transfer power along the cable at
`
`20
`
`a high frequency due to the length of the cable, amount of power required to be
`
`distributed, and the noise generated by such a transfer. Accordingly, power is typically
`
`transferred along the entire length of the cable at a low frequency. However, low
`
`frequency signals are extremely inefficient when coupled across a transformer having a
`low coupling coefficient. Thus, configurations which couple power from the main power
`
`25
`
`line may be commercially impractical in many applications.
`
`Another shortcoming of conventional streamer power distribution and/or data
`
`communication systems may be reliability problems due to the leakage of seawater into
`
`one or more of the sections of the streamer cable. As seawater leaks into a section of the
`
`underwater streamer cable, a low-impedance path or short circuit may be formed across
`
`30
`
`In a continuous-wire transmission line running the length of the
`the transmission line.
`underwater cable, the short circuit may disable the entire transmission line. When the
`
`transmission line is disabled, sensor data cannot be collected, the electrical devices cannot
`
`be powered from the underwater cable, and depth control from the survey vessel may be
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`3
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`SUBSTITUTE SII£ET (RillE 21)
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`Ex. PGS 1059
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`W097111394
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`precluded.
`
`PCT/US96/15128
`
`Thus, there is a need for an underwater cable power distribution and/or data
`
`communication system that overcomes these and other problems and enables highly
`
`efficient and reliable transmission of power and data between the underwater cable and the
`
`5
`
`electrical devices even under demanding operational conditions.
`
`Summary of the Invention
`
`A principal object of the present invention is to provide a power distribution and/or
`
`data communication system which provides an elegant and reliable power distribution and
`
`data communication system for supplying power and data to a plurality of electrical
`
`10
`
`devices disposed along an underwater cable.
`
`The power distribution and/or data
`
`communication system may also provide an improved structure and/or operation which
`
`enhances the reliability of the seismic streamer cable assembly even when the cable is
`
`damaged and/or electrical devices are removed.
`
`Additional objects of various aspects of the present invention include providing an
`
`15
`
`underwater cable structure which enables the transferring of operational power to the
`
`electrical devices without breaching the outer sheath of the underwater cable; eliminating
`
`batteries as the primary source of operational power for the electrical devices coupled to
`
`the underwater cable; eliminating and/or reducing the need to change batteries; providing
`
`better economy by enabling an underwater cable assembly to survey for more hours
`
`20 without interruptions; extending the operational length of underwater cables by 5, 10, 15,
`
`20 krn or more without altering the basic structure and/ or operation of the underwater
`
`cable power distribution and/or data communication system; increasing the bandwidth of
`
`data transmitted to and received from the electrical devices; minimizing the weight of
`
`wires (e.g., copper wires) in the underwater cable; reducing the weight, size, and number
`
`25
`
`of inductive cores used along the underwater cable; allowing brittle cores to be used in
`
`inductors along the underwater cable;
`
`increasing the power transfer efficiency from a
`
`main power supply to the electrical devices disposed along the underwater cable; reducing
`
`noise generated by the power transfer which may interfere with the seismic equipment;
`
`reducing capacitive coupling and mutual inductance between the electrical devices and
`
`30
`
`other parts of the underwater cable;
`
`improving the coupling coefficient of a transformer
`
`disposed about the outer sheath of the underwater cable; providing a fault tolerant power
`
`distribution and data communication system in an underwater cable assembly; reducing the
`
`4
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`SUBSTOUIE SIIEEf (RULE 21)
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`Ex. PGS 1059
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`W097/ll394
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`PCT/US96/1Sll8
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`number of data and power transmission lines coupled to each of the electrical devices and
`
`time associated with
`latency
`the
`reducing
`the underwater cable;
`in
`disposed
`communications through the underwater cable with the electrical devices; allowing the
`
`electrical devices to respond directly to detected fault conditions without intervention of
`
`5
`
`dry-end electronics; and providing for degraded mode operations which allow the most
`
`critical electrical device operations to be maintained even during fault conditions.
`
`Accordingly, the present invention provides an underwater power distribution system
`
`including an underwater cable for powering a plurality of electrical devices disposed along
`
`the cable. A main power line extends through the underwater cable. Two or more power
`
`10
`
`distribution lines and two or more power distributors are also disposed in the underwater
`
`cable. Each power distributor is electrically coupled between the main power line and one
`
`of the power distribution lines to transfer power from the main power line to the
`
`associated power distribution line. One or more power couplers are disposed at selected
`
`locations along the underwater cable. Each power distribution line is coupled to one or
`15 more power couplers proximate to one of the electrical devices for coupling power to the
`
`proximate device.
`
`In underwater systems embodying this aspect of the invention, power may be
`
`transmitted along the main line and then distributed to the electrical devices by the power
`distribution lines. Each power distribution line distributes power directly to a small
`
`20
`
`subgroup of the electrical devices. This arrangement is particularly advantageous.
`
`It
`
`allows both power transmission along the main line and power distribution along the
`
`distribution lines to be independently optimized regardless of the length of the underwater
`
`cable assembly, resulting in a highly reliable and efficient underwater power distribution
`
`system. Systems embodying this aspect of the invention are so reliable and so efficient
`
`25
`
`that batteries may either be eliminated entirely from the electrical devices or used only
`rarely in a fail safe capacity. Thus, this aspect of the invention virtually eliminates the
`
`economic loss associated with retrieving an underwater cable and replacing or recharging
`
`the batteries in the electrical devices and greatly extends the operational life of an
`
`underwater cable assembly.
`In addition, this arrangement of a main power line and several power distribution
`
`30
`
`lines allows segmentation of the underwater cable assembly. For example, each power
`
`distribution line and the subgroup of electrical devices coupled to that power distribution
`
`line may define a different segment of the underwater cable assembly. This arrangement
`
`5
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`SUBSTI1UT£ SEr (Rill! 21)
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`further enhances the reliability of an underwater cable assembly because it provides a
`
`highly fault-tolerant system. Each segment may be provided with fault protective features
`
`that isolate a fault, such as seawater intrusion or loss of an electrical device, in that
`
`segment but preserve power transfer and data communications to the remaining segments
`
`5
`
`of the underwater cable assembly.
`
`Further, segmentation of the underwater cable
`
`assembly allows the cable assembly to be easily lengthened simply by adding additional
`
`segments, i.e., by extending the main power line and adding additional power distribution
`
`lines.
`
`The invention also provides an underwater power distribution system for powering
`
`10
`
`electrical devices. The underwater power distribution system includes an underwater
`
`cable including two or more streamer electronics modules and two or more cable
`
`segments. At least one of the electrical devices is disposed along each cable segment, and
`
`the streamer electronics modules are alternately arranged with the cable segments and
`
`spaced from the electrical devices. A main power line extends through the underwater
`
`15
`
`cable. Two or more power distribution lines are disposed in the underwater cable with at
`
`least one power distribution line extending through each cable segment. Each streamer
`
`electronics module includes a circuit for coupling electric power from the main power line
`
`to an adjacent power distribution line. Two or more power couplers are disposed at
`
`selected locations along the underwater cable. Each power distribution line is coupled to
`
`20
`
`one or more power couplers and each power coupler is positioned proximate to at least
`
`one of the electrical devices to couple power to the proximate device.
`
`Systems embodying this aspect of the invention may be similar to, and have many of
`
`the same advantages as, the previously described underwater power distribution system.
`
`However, in systems embodying this aspect of the invention, the underwater cable
`
`25
`
`comprises alternately arranged streamer electronics modules and cable segments, and at
`
`least one power distribution line branches from the main power line at a streamer
`
`electronics module. This arrangement allows much of the circuitry, including power
`
`supplies, data circuits, and circuit cards to be consolidated with existing circuitry in the
`
`streamer electronics modules and,
`
`therefore, significantly reduces the weight and
`
`30
`
`complexity added to the underwater cable assembly to effect power transfer to the power
`
`distribution lines.
`
`The invention provides a method for distributing power underwater to one or more
`
`electrical devices disposed along an underwater cable. The method comprises transmitting
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`6
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`IKDTUrE SHEET (RIU Jl)
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`Ex. PGS 1059
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`power at a first frequency on a main power line of the underwater cable, converting the
`
`power on the main power line to a second frequency, higher than the first frequency, and
`
`distributing the power at the second frequency on two or more power distribution lines to
`
`the electrical devices. The first frequency may be either a DC frequency of zero or an
`
`5 AC frequency having a value greater than zero.
`
`The invention also provides an underwater power distribution system for powering
`
`two or more electrical devices. The underwater power distribution system includes an
`
`underwater cable and the devices are disposed along the underwater cable. A main power
`
`line extends through the underwater cable and is arranged to transmit a main power signal
`
`10
`
`at a first frequency. A plurality of conversion circuits are disposed at spaced locations
`
`along the underwater cable and are respectively coupled between the main power line and
`
`the electrical devices. Each conversion circuit is arranged to convert the main power
`
`signal into a power distribution signal at a second frequency higher than the first
`
`frequency.
`
`15
`
`In methods and systems embodying these aspects of the invention, power is
`
`transmitted along the main power line at one frequency and is distributed to the electrical
`
`devices along the underwater cable at a higher frequency. This arrangement greatly
`
`increases the power transfer efficiency along the main line and to the electrical devices.
`
`Transmitting power at a relatively low frequency along the main power line allows the
`
`20
`
`power to be most efficiently transmitted to the aft end of the underwater cable.
`
`Converting the lower frequency main power signal to a higher frequency power
`
`distribution signal allows the power to be most efficiently distributed from the main power
`
`line to the electrical devices. This is especially advantageous where the electrical devices
`are mounted external to the underwater cable and power is inductively or capacitively
`
`25
`
`coupled through the sheath of the underwater cable without any connectors physically
`
`penetrating the sheath. The high frequency signal inductively couples power through the
`
`sheath far better than a low frequency signal.
`
`In some embodiments employing these aspects of the invention, it may be desirable
`
`to first convert the main power signal into a DC signal and then to convert the DC signal
`
`30
`
`into a higher frequency power distribution signal. Conversion first to a DC signal may
`
`further improve the efficiency of the power conversion process.
`
`The invention provides an underwater power distribution system for supplying
`
`power. The underwater power distribution system includes an underwater cable and two
`
`7
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`or more electrical devices selectively disposed along the underwater cable.
`
`The
`
`underwater cable has an outer sheath and is filled with a lossy dielectric material having a
`
`dissipation factor of about 0.01 or greater. A main power line extends through the
`
`underwater cable. A plurality of insulated twisted pair transmission wires extend through
`
`5
`
`the underwater cable and are coupled between the main power line and the electrical
`
`devices. Each twisted pair transmission wire has an outer sheath and a dissipation factor
`
`of less than about 0.01 when surrounded by the lossy dielectric material.
`
`Systems embodying this aspect of the invention very effectively transfer power along
`
`an underwater cable to electrical devices even when the underwater cable is filled with a
`
`10
`
`lossy dielectric material, such as a non-aqueous liquid that maintains the underwater cable
`
`in a neutrally buoyant state. By providing an outer sheath on the transmission wires that
`
`has a dissipation factor of less than about 0.01 in the lossy material, power can
`
`nonetheless be very effectively transferred along the underwater cable, through the power
`
`distribution lines, to the electrical devices.
`
`15
`
`The invention also provides an underwater system for distributing power to and
`
`communicating with two or more electrical devices. The underwater system includes an
`
`underwater cable and the electrical devices are selectively disposed along the cable. Each
`
`device includes one or more loads. A first line extends through the underwater cable and
`
`is coupled to the electrical devices. Fault detection circuitry is coupled to the first line to
`
`20
`
`detect when a fault is present. Disabling circuitry is coupled to the fault detection
`
`circuitry to disable one or more of the loads in a hierarchical order in response to a fault.
`
`The invention also provides a method for distributing power along an underwater
`
`transmission system. The under water transmission system includes an underwater cable
`
`having two or more electrical devices spaced along the underwater cable, and each device
`
`25
`
`includes one or more loads. The method includes transferring electrical signals along the
`
`underwater cable, detecting a fault in the underwater transmission system, removing loads
`
`along the underwater cable in a hierarchical order in response to the fault, and powering
`
`the remaining loads.
`
`The invention further provides a method for distributing both power and data along
`
`30
`
`an underwater cable. Two or more spaced electrical devices are coupled to the
`
`underwater cable and each device includes one or more electrical loads. The method
`
`includes transferring power and data along a line in the underwater cable, detecting a
`
`fault, and selectively removing one or more of the electrical loads from the underwater
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`cable according to a predetermined hierarchy in response to the fault.
`
`Systems and methods embodying these aspects of the invention respond to a failure
`
`in a power line or a data distribution line by selectively removing, e.g., shutting down,
`various loads and associated functions in a controlled, hierarchical manner. The least
`
`5
`
`important functions or electrical devices are shut down first and the most important
`
`functions or electrical devices are shut down last. Alternatively, all electrical devices or
`
`functions may be shut down responsive to the fault, and then the most important electrical
`
`devices added in a controlled, hierarchical manner provided sufficient power is present.
`
`This management enhances the survivability of the more critical functions or devices
`
`10
`
`in the damaged section of the cable as well as the survivability of other functions or
`
`devices disposed at undamaged sections of the cable. Shedding the electrical load
`
`associated with various functions or devices, and particularly hierarchical load shedding,
`
`has even greater importance where both power and data are disposed on a single
`distribution line. Load shedding allows power transfer and communications to or from aft
`
`15
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`electrical devices to remain intact even when an intermediate cable segment has been
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`damaged.
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`The invention provides an underwater power distribution system for powering two
`
`or more electrical devices. The underwater power distribution system includes an
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`underwater cable with the electrical devices selectively spaced along the cable. A power
`line extends through the underwater cable and is coupled to the electrical devices. A
`
`20
`
`current limited driver circuit is coupled to the power line to drive a power distribution
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`signal on the power line at or below a predetermined current level. A fault detection
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`circuit is also coupled to the power line. The fault detection circuit includes a voltage
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`detection circuit for detecting a change in the voltage on the power line.
`Systems embodying this aspect of the invention allow a fault to be quickly detected
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`25
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`autonomously by each of the electrical devices or by each segment of the underwater cable
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`without intervention of the survey vessel. For example, where the current on each power
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`line is limited, a short circuit or other current leakage fault, such as sea water intrusion,
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`causes a drop in voltage to occur on the power distribution lines. A fault (e.g., sea water
`intrusion) may be detected simply by a monitoring a voltage received from the power line,
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`30
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`e.g. , by detecting a reduction in the voltage on the power line. Further, the current
`limited driver not only provides for autonomous fault detection, but also prevents a section
`
`of the underwater cable from exceeding a predetermined power budget due to the fault.
`
`9
`
`STIIUTE SHEET (RUII 21)
`
`Ex. PGS 1059
`
`

`
`wo 97/11394
`
`PCTIUS96/15128
`
`Excess power drawn from one or more cable sections may adversely affect the entire
`
`operation of the underwater cable.
`
`The invention further provides an underwater power/data transfer system comprising
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`an underwater cable and a mechanism associated with the cable for transfering power
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`5
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`and/or data along, into, or out of the cable.
`
`The invention further provides a device associated with an underwater cable
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`comprising a mechanism for sending, receiving, or generating power and/or data.
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`The invention further provides an underwater data communications system for
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`communicating with a plurality of electrical devices, and includes a primary data
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`10
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`communications circuit, a backup data communications circuit, and circuitry coupled to
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`the primary data communications circuit and the backup data communications circuit to
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`switch between
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`the primary data communications circuit and
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`the backup data
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`communications circuit in response to a loss of power to the electrical devices.
`
`The invention provides an underwater communication system for communicating
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`15 with two or more electrical devices. The underwater communication system includes an
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`underwater cable with the electrical devices selectively disposed along the underwater
`
`cable. An inbound data distribution line and an outbound data distribution line extend
`
`through the underwater cable and are coupled to one or more of the electrical devices. At
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`least one repeater circuit is disposed in the underwater cable. The repeater circuit
`
`20
`
`includes synchronization circuitry coupled to the inbound and outbound data distribution
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`lines to derive clock data from the outbound data and to transmit the inbound data in
`
`accordance with the derived clock data so that a timing relationship exists between
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`inbound and outbound data.
`
`The invention also provides a method of communicating data underwater. The
`
`25 method comprises transmitting outbound data and inbound data through a repeater circuit
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`in an underwater cable, decoding the outbound data in the repeater circuit to recover clock
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`data, and transmitting inbound data from the repeater circuit in synchronism with the
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`clock data.
`
`The invention further provides another method for communicating data underwater.
`
`30 The method comprises receiving outbound data along an underwater cable, decoding the
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`outbound data to recover a clock signal, and transmitting inbound data along the
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`underwater cable in synchronism with the data clock.
`
`In systems and methods embodying these aspects of the invention, transmission of
`
`10
`
`.-nnnt SHEEr (RUlE 21)
`
`Ex. PGS 1059
`
`

`
`wo 97111394
`
`PCT/US96/15128
`
`inbound data along an underwater cable is synchronized according to a clock derived from
`
`the outbound data. Synchronization of the inbound data with the outbound data by the
`
`repeaters, electrical devices, and dry-end electronics greatly reduces the latency, i.e., the
`
`time delay, associated with sending an inbound electrical signal from an electrical device,
`
`5
`
`resulting in more efficient utilization of the available bandwidth. Further, since the
`
`electrical devices are already synchronized with each of the repeaters and the dry-end
`
`electronics, there is no need to send out a long preamble to achieve synchronization with
`
`each repeater and the dry-end electronics. Thus, in accordance with these aspects of the
`
`invention, data may be sent inbound from the electrical devices to the survey vessel very
`
`10
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`quickly and efficiently.
`
`The invention provides an underwater system for transferring power.
`
`The
`
`underwater power transferring system includes an underwater cable and two or more wet
`
`units selectively disposed along an underwater cable. Each wet unit has a first inductor
`
`for receiving power. The underwater cable includes two or more second inductors
`
`15
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`respectively disposed adjacent to the first inductors in the wet units. Hydrophones are
`
`also selectively disposed along the cable and operate in one or more first operating
`
`frequency bands. Power conversion circuits are res