Seafloor Characterization And Mapping Pods (SCAMP) Submarine-mounted Geophysical Mapping50
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Seafloor Characterization And Mapping Pods (SCAMP) Submarine-mounted Geophysical Mapping50
SeafloorCharacterization；Submarine-mountedGeophys；DaleN.Chayes1RobertM.And；MarkR.Rognstad5,RogerB.D；Lamont-DohertyEarthObser；ArcticSubmarineLaborator；JohnsHopkinsAppliedPhysi；Tulan
Seafloor Characterization And Mapping Pods (SCAMP):Submarine-mounted Geophysical MappingDale N. Chayes1Robert M. Anderson2Stuart Goemmer3Jose L. Ardai1Bernard J. Coakley4Mark R. Rognstad5, Roger B. Davis5, Margo Edwards51Lamont-Doherty Earth Observatory of Columbia University2Arctic Submarine Laboratory, US Navy3Johns Hopkins Applied Physics Laboratory4Tulane University5Hawaii Mapping Research Group, University of HawaiiAbstractIn 1998 the Seafloor Characterization andMapping Pods (SCAMP) were deployed on theUS Navy nuclear attack submarine USSHAWKBILL (SSN666) for unclassified swathmapping and subbottom profiling under the Arcticice canopy. Data was collected under the SCICEXprogram, which is guided by the terms of amemorandum of agreement between the Navy,the Office of Naval Research, the NationalScience Foundation (NSF), the U.S. GeologicalSurvey and the National Oceanic andAtmospheric Administration. SCAMP consists of aSidescan Swath Bathymetric Sonar (SSBS) and aHigh-Resolution Subbottom Profiler (HRSP), anda marine gravity meter that are integrated with aphysically compact Data Acquisition and QualityControl System (DAQCS).The transducers for each of the sonars aremounted in purpose-built hydrodynamic pods thatare temporarily fastened to special purposethreaded weldments along the boat's keel. Theweldments were installed in drydock but the pods,transducers and junction boxes were installed andcan be serviced by divers at the pier. The inboardelectronics for the system are packaged forsubmarine installation and mounted in the torpedoroom.The SSBS is a 12 kiloHertz SeaMARC designadapted for under-ice mapping by adding transmitand receive beam forming and shading tosuppress spurious returns from the ice canopy.Transducers are housed in a keel-mounted podwith electronics mounted outside the pressure hullbut above the water line when surfaced. Swathimage data is produced over a 135 to 140 degreeswath centered at nadir while high qualitybathymetry covers a 120 degree swath.The HRSP is a Bathy-2000P FM modulatedsubbottom profiler adapted for submarineinstallation and operation. It produces high qualitysubbottom data using an array of 9 DT-109transducers driven by a 2 kilowatt transmitter.Seafloor penetration in excess of 100 meters witha resolution of tens of centimeters is common insediment filled areas of the Arctic basins.Initial at-sea tests on the submarine wereconducted out of Pearl Harbor, Hawaii in May1998. The first deployment in the Arctic took placeduring SCICEX-98 during which more than 30days of data were collected in the data releasearea. Substantial improvements to the systemwere completed and tested in January andFebruary 1999.
The second deployment in theArctic was completed in May of 1999.I. IntroductionThe Seafloor Characterization and MappingPods (SCAMP) were developed to allow moderngeophysical survey techniques to be added to theSCICEX program of unclassified research fromUS Navy nuclear submarines operating in theArctic. The SCICEX program is discussed byGosset [1] and Pyle et. al. [2].
Langseth et. al.[3]describes the first unclassified research cruiseusing a nuclear submarine in the Arctic, which ledto the creation of the SCICEX program. In manyways nuclear submarines are ideal platforms forunderway geophysical and synopticoceanography mapping because of their speed,stability, low noise and stability, and freedom tomaneuver below the ice canopy.The SCAMP development process and designissues were reported by Chayes et. al. [5] [6].SCAMP was subsequently installed on the USSHawkbill in the spring of 1998 in Pearl Harbor anddeployed to the Arctic during SCICEX98
(August1998) and SCICEX99 (April and May 1999). Atotal of approximately seventy days of underwaysurvey has been accumulated during thesecruises.II. SubsystemsSCAMP consists of two sonar systems, amarine gravity meter and the data system thatlogs the data and provides on-board qualitycontrol. One sonar is a bilateral swath mapperthat produces bathymetry and image data referredto as the Sidescan Swath Bathymetric Sonar afterBlackinton [4]. The other SCAMP sonar is asubbottom profiler known as the High ResolutionsSubbottom Profiler (HRSP.) Data from a BellBGM-3 marine gravity meter is logged by theSCAMP Data Acquisition and Quality ControlSystem (DAQCS). DAQCS also logs data from asail mounted CTD and the submarines navigationsystem.A. Swath Mapping SonarThe Sidescan Swath Bathymetric Sonar(SSBS) system is based on the provenSeaMARC? design with adaptations forsubmarine-mounted operation and to optimizeperformance while operating under an ice canopy.The SSBS was manufactured by RaytheonSystems Corporation.Frequency12 kHzPulse Length83 μS to 10 mSModulationCWRepetition Rate2 to 20 secondsSource level230 dB re 1Power115 VACImage Swath Width~160°Bathymetry Swath~140°WidthTable 1: Characteristics of the SCAMP SidescanSwath Bathymetric Sonar.Figure 1 and Figure 2 show preliminary resultsfrom the SSBS during SCICEX99. Figure 1 showsiceberg scours from the top of the LomonosovRidge in 675 meters of water. Figure 2 shows acolor coded contour plot of gridded, processedSSBS bathymetry across the NorthwindEscarpment.B. Subbottom ProfilerThe SCAMP High Resolution SubbottomProfiler (HRSP) is a modified version of OceanData Equipment Corporation's Bathy-2000P.Significant re-packaging of the inboard electronicswas required to meet the space requirements andthe transducers were designed to operate atdepth.Frequency:3.75-6.75 kHzPulse Length:1 - 50 mSModulation:CW or FMSource level:218 dB re 1 μPl @ 1 mAthwartships~30°beam width:Fore/Aft beam~30°widthRepetition Rate:1-10SPenetrationup to 200mResolution~10s of cmTable 2: Operational characteristics of theSCAMP HRSP. Under optimum sedimentconditions penetration in excess of 200 metershas been observed.Figure 3 shows HRSP data collected in theBarents Basin along the transit from the GakkelRidge to the Yermak Plateau. Well laminatedsediments, with some evidence of diapiricdisruption, characterize the abyssal plain.C. DAQCSThe DAQCS provides the computerinfrastructure to support the data acquisition,logging and validation necessary for successfuldata collection at sea. The version implementedfor SCAMP is evolved from a sequence ofsystems that originated on the R/V Conrad in1985 running on single processor 68010 basedMasscomp computers under a real-time Unixvariant called RTU. Over time the core systemhas been expanded and adapted to run on Sparc-based single and multi-processors under asuccession of Sun Operating systems from Sun-OS 3.1 through Solaris 5.3, under X86-basedLinux systems, and on several generations ofMIPS-based single and multi-processors fromSilicon Graphics.In the SCAMP implementation there are twoSun Ultra2 servers rack mounted in ArteconSphinx enclosures, which also contain additionalperipherals. One server acts as the real-timesystem while the other is used for offline dataarchiving and quality control. To save space in thesubmarine environment, interaction with DAQCSis provided through laptop computers.
Three NEC6050MX laptops running a RedHat Linuxdistribution provide the principal displays by wayof X11 servers. In addition to being fullynetworked through a switching hub, one laptop isconnected to the first serial interface of eachUltra2 (/dev/ttya) to provide single user and boottime control through a terminal emulator (kermit)running on the laptop.The real-time system interfaces with the SSBSthrough an S-Bus interface card that implements ahigh speed digital interface known as a TI 'C40comport. Software provided by Raytheon providesthe real-time displays necessary to operate theSSBS and to capture its data to disk. Additionalsoftware collects the SSBS data from disk, appliesa narrow band decimation filter and translates theSSBS data from “atk” format provide by theRaytheon code into “tts” format that is used insubsequent data processing. The tts-format filesare decimated by a factor of five as part of thenarrow band filtering.The interface between DAQCS and the HRSPhas several data channels. Time, position anddepth data are provided to the HRSP fromDAQCS via a serial interface. Two statusmessage streams (one for routine messages andanother for errors) are transferred from the HRSPto DAQCS via serial interfaces. The HRSP sonardata is written across a 10BT network connectionto one of the DAQCS disks using the Network FileSystem protocol.Digital data from the Submarine DataRecording System (providing ship's own position,depth, speed and attitude), the second sailmounted CTD (to derive sound speed), and fromthe Gravimeter come to DAQCS for real-timedisplay on unidirectional asynchronous serialinterfaces.The SSBS data is internally time-tagged withDAQCS CPU time by the Raytheon suppliedsoftware. The HRSP is time-synchronized withDAQCS via serial interface and applies this timestamp to the data files it creates. The SDRS datastream has two times imbedded in it: one from theship's precision frequency reference and a secondthat is simply the CPU time of the SDRScomputer. All other data streams have DAQCSCPU time prepended to the data message.III. InstallationInstallation, removal and maintenance issuesare a crucial part of the success of SCAMP. JohnsHopkins Applied Physics Lab provided invaluableassistance with this aspect of SCAMP, based ontheir substantial experience with a large numberof other submarine based programs.A. BackgroundSubmarine installations must be designed toassure optimum system performance, maintainship performance and assure personnel safety.Identification of external equipment locations iscritical because hull attachment, cabling,serviceability pose the biggest challenges. Systemperformance is optimized by selecting the bestoperating position on the hull, maintainingappropriate separation from ship's systems, andproperly orienting sensors. For bottom-mappingsystems, keel mounted sensors arerecommended to minimize hull interference andmaximize sensor performance. Sensor orientationwould be symmetrical. Also, attachment issimplified because roll is zero and pitch is small,and no aneochic tiling has to be removed.Typical hull-mounted structures consist of afoundation and pod. The foundation provides a flatsurface to attach the pod while accounting for hullcurvature and ship frame locations. Attachmentpoints must be located at frame locations to avoidpossible hull distortion. The typical attachmenttechnique involves welding cylindrical mountingpads to the hull. Each pad has a tapped holewhich results in a hull attachment pointsignificantly stronger than simply welding a stud tothe hull. The number of pads and size of hardwaredepend upon the size of the pod and number offrames in the pod location. Below-the-waterlinewelding and anechoic tile removal requires dry-docking the submarine because of the precisionrequired. A skirt, which is fitted during theinstallation, is attached to the foundation to ensureno gaps between the foundation and hull exist.These gaps could cause hydrodynamic noise.Criteria for attaching hull-mounted structures aredefined by the Naval Sea Systems Command.The pod houses the sensor(s) in ahydrodynamic shape that is readily removed fromthe foundation. Typically pods are designed tohave NACA or &tear drop& shape where the lengthis at least 4 to 5 times the pod's width to minimizehydrodynamic noise. An example of a NACAshape is the submarine's sail. The top of the podis typically domed.Cable routing is simplified if the pod is locatednear the submarine's forward main ballast tanks(MBTs). MBTs and free flood areas typically havewireways, electrical hull penetrators, and tankpenetrators located within them for servicingvarious ship systems. Electrical penetrators areelectrical connections that penetrate the pressurehull of a submarine, and tank fittings. Penetratorsare conduits that pass cables between ballasttanks and between ballast tanks and free floodareas such as the sail and torpedo tubelaunchways. Cables can be routed into MBTseither through MBT grates or by cutting holes inthe nonpressure hull hear the grates as long asthe hole is not above the grate resulting in a risein the MBT residual waterline. Identifying andutilizing available space in existing electrical hullpenetrators and tank penetrators is preferred.Replacing existing electrical hull penetratorsand/or tank penetrators with new penetrators thataccommodate both existing cables and newcables is very complex and expensive.Replacement of a penetrator could add a fiberconductor in addition to or in lieu of an existingelectrical conductor, but at great expense.B. USS Hawkbill InstallationThe SCAMP installation on the USS Hawkbillconsists of a Sidescan Swath Bathymetric Sonar(SSBS) and a High Resolution Subbottom Profiler(HRSP). The pod containing the SSBS is mountedon the underside of the keel below the sail, andthe pod containing the HRSP is also mounted tothe underside of the keel approximately 17 feetforward of the SSBS pod. Both pods are locatedsuch that the forward end of the pod overlaps aMain Ballast Tank (MBT). The SSBS and HRSPinboard electronics are mounted in shallow depth19& relay racks on a torpedo skid plate in theTorpedo Room. A Remote Display and blankingswitch are
mounted in the Control Room.Both the SSBS and HRSP pods are attachedto the hull via foundations and cylindricalmounting pads. A hole was cut in the non-pressure hull above each pod to allow cables tobe routed into the ballast tanks. Each pod hasforward and aft composite fairings attached to thestainless steel skeletal structural members.The HRSP pod contains nine ITC-5465transducers in a 3 by 3 matrix. These transducersare mounted in a plane parallel to the pod/hulltangent point at 0
pitch. They areconnected to a junction box mounted in the ballasttank immediately above the forward end of thepod with underwater mateable connections. Thejunction box has a single cable output that isrouted through an existing cable pipe to a freeflood cavity topside where it connects to anexisting ship's electrical penetrator.The SSBS pod carries ten ITC-5485subbarrays, five port looking and five starboardlooking. These transducers are mounted a 0
pitchand tilted such that the bore sight is 25
downfrom horizontal. Independent port and starboardjunction boxes are mounted in the MBT above theforward end of the pod. Each subarray has asingle multi-conductor cable routed to its junctionbox with an underwater matable connector. Eachjunction box has a single multi-conductor cable,which is routed through the ballast tank into atopside free flood space (the ESM Void under theforward edge of the sail) by way of an existingtank penetrator. The cable from, each side'sjunction box is mated to that sides transceiverelectronics, which is mounted in the void.The SSBS outboard power, telemetry andcontrol electronics are contained in a thirdpressure case also mounted in the ESM void.Power and telemetry are carried through the hullvia an existing seven conductor electrical hullfitting from the ESM Void into the Control Room.AcknowledgementsMarcus Langseth was a substantial drivingforce behind the process that led to thedevelopment of SCAMP. Financial support for thisprogram has come primarily from the Arcticsection of the National Science Foundation Officeof Polar Programs with assistance from thePalisades Geophysical Institute and thegovernments of Canada, Norway and Sweden.Numerous individuals in the Navy have providedinvaluable support and assistance in keeping thisprogram on track. Bob Perry, Commanding Officerof the USS Hawkbill, his officers and crew havedone an outstanding job in supporting theSCICEX program and SCAMP.References:[1] Gossett, J. (1996.). “Arctic Research UsingNuclear Submarines.” Sea Tech March.[2] Pyle, T. E., M. Ledbetter, et al. (1997). “ArcticOcean Science.” Sea Technology 38 No.10(October 1997): 10-15.[3] Langseth, M., Theodore Delaca, et al.“SCICEX-93: Arctic Cruise of the US NavyNuclear Powered Submarine USS PARGO.”MTS Journal 27(4).[4] Blackinton, J. G. (1991). BathymetricResolution, Precision and AccuracyConsiderations for Swath BathymetryMapping Sonar Systems. IEEE Oceans '91,Honolulu
Hawaii, IEEE.[5] Chayes, D. N., B.J. Coakley, et al. (1996).“SCAMP: An Enhanced Geophysical Mapping77 (315.).[6] Chayes, D. N., B. J. Coakley, et al. (1997).SCAMP: A submarine-mounted geophysicalsurvey system for use under the Arctic ice.Oceans' 97, Halifax, NS, IEEE.包含各类专业文献、行业资料、外语学习资料、文学作品欣赏、应用写作文书、各类资格考试、专业论文、幼儿教育、小学教育、Seafloor Characterization And Mapping Pods (SCAMP) Submarine-mounted Geophysical Mapping50等内容。502 Bad Gateway
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