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  • 1
    Publication Date: 2007-02-01
    Description: As part of a program aimed at developing a long-duration, subsurface mooring, known as Ultramoor, several modern acoustic current meters were tested. The instruments with which the authors have the most experience are the Aanderaa RCM11 and the Nortek Aquadopp, which measure currents using the Doppler shift of backscattered acoustic signals, and the Falmouth Scientific ACM, which measures changes in travel time of acoustic signals between pairs of transducers. Some results from the Doppler-based Sontek Argonaut and the travel-time-based Nobska MAVS are also reported. This paper concentrates on the fidelity of the speed measurement but also presents some results related to the accuracy of the direction measurement. Two procedures were used to compare the instruments. In one, different instruments were placed close to one another on three different deep-ocean moorings. These tests showed that the RCM11 measures consistently lower speeds than either a vector averaging current meter or a vector measuring current meter, both more traditional instruments with mechanical velocity sensors. The Aquadopp in use at the time, but since updated to address accuracy problems in low scattering environments, was biased high. A second means of testing involved comparing the appropriate velocity component of each instrument with the rate of change of pressure when they were lowered from a ship. Results from this procedure revealed no depth dependence or measurable bias in the RCM11 data, but did show biases in both the Aquadopp and Argonaut Doppler-based instruments that resulted from low signal-to-noise ratios in the clear, low scattering conditions beneath the thermocline. Improvements in the design of the latest Aquadopp have reduced this bias to a level that is not significant.
    Print ISSN: 0022-3670
    Electronic ISSN: 1520-0485
    Topics: Geosciences , Physics
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  • 2
    Publication Date: 2022-05-25
    Description: An Engineering Surface Oceanographic Mooring (ESOM) program was initiated in 1989 by the Woods Hole Oceanographic Institution for the purpose of evaluating the long term, in situ performance of new moored array materials and sensors. For logistic and practical reasons, a site 12 miles southwest of Bermuda, with a water depth of 3000m was selected to deploy the mooring. Following well established design practice the upper part of the mooring down to a depth of 1900m was made of plastic jacketed, steel armored wire ropes and cables. Groups of test samples were attached at different depths to the main mooring line. The lower part of the mooring was made of compliant, plaited nylon rope. The mooring was deployed in March 1989. It was recovered and reset, with a vertical acoustic telemetry prototype system, in April 1990. The at-sea phase of the program ended in November 1990 when the termination of a test cable failed and the mooring broke loose. The entire mooring was recovered and all of its samples and components were carefully inspected and tested. In addition to the novel acoustic link, mooring components tested included new wire ropes, new electromechanical cables and their terminations, low drag fairings, fishbite resistant jackets, and a new type of surface buoy.
    Description: Funding was provided by the Office of Naval Research under Contract No. N00014-90-J-1719.
    Keywords: Mooring components ; Fishbite ; Acoustic telemetry
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: 3728872 bytes
    Format: application/pdf
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  • 3
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-25
    Description: The Advanced Engineering Laboratory of the Woods Hole Oceanographic Institution is a development laboratory within the Applied Ocean Physics and Engineering Department. Its function is the development of oceanographic instrumentation to test developing theories in oceanography, and to enhance current research projects in other disciplines within the community. This report summarizes recent and ongoing projects performed by members of this laboratory.
    Keywords: Engineering projects ; Advanced Engineering Laboratory projects ; Ocean instrumentation
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: 2704566 bytes
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  • 4
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-25
    Description: The Advanced Engineerig Laboratory of the Woods Hole Oceanographic Institution is a development laboratory within the Applied Ocean Physics and Engineering Department. Its function is the development of oceanographic instrumentation to test developing theories in oceanography, and to enhance current reseach projects in other disciplines within the community. This report summarizes recent and ongoing projects performed by members of this laboratory.
    Keywords: Advanced Engineering Laboratory ; Electronic systems ; Oceanographic instrumentation
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: 4143943 bytes
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  • 5
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: The Advanced Engineering Laboratory of the Woods Hole Oceanographic Institution is a development laboratory within the Applied Ocean Physics and Engineering Deparment. Its function is the development of oceanographic instrumentation to enhance current research projects in other disciplines within the community. This report summarizes recent and ongoing projects performed by members of this laboratory.
    Keywords: Engineering projects ; Advanced Engineering Laboratory projects ; Ocean instrumentation
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: 1080394 bytes
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  • 6
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: The Advanced Engineering Laboratory of the Woods Hole Oceanographic Institution is a development laboratory within the Applied Ocean Physics and Engineering Deparment. Its function is the development of oceanographic instrumentation to test developing theories in oceanography, and to enhance current research projects in other disciplines within the community. This report summarzes recent and ongoing projects perfomied by members of this laboratory.
    Keywords: Advanced Engineering Laboratory ; Electronic systems ; Oceanographic instrumentation
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: 2812846 bytes
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  • 7
    Publication Date: 2022-05-26
    Description: The Atlantic Long-Term Oceanogrphic Mooring (ALTOMOOR) has been maintained offshore Bermuda since 1993 as a testbed for the evaluation of new data telemetry technologies and new oceanographic instrumentation. It is currently a joint project between the Woods Hole Oceanographic Institution and the University of Southern California This report documents the WHOI contributions which have focused on the development of new data telemetry methods and new mooring technology. Details of the instrumentation evaluations will be published separately. A new inductively-coupled telemetry technology for ocean moorings has been developed and tested on ALTOMOOR. The inductive link uses standard, plastic-jacketed mooring wire as the transmission path for data generated at the individual instruments installed on the mooring. The signals are inductively linked to the mooring wire via toroids clamped around the wire, thus avoiding the need for multiconductor electromechanical cables terminated at each instrument. Seawater provides the electrical return path. The inductive modems send and receive data at 1200b/s. A controller in the surface buoy collects data from each of the subsurface instruments and forwards the data to shore by traditional satellite telemetry (Argos) and by short range radio using a nearby ship as a store and forward node. The buoy-to-ship link operates over about 2 km at 10kBytes/sec. When the ship docks, data are offloaded automatically to a computer on shore which can be accessed via the Internet.
    Description: Funding was provided by the Office of Naval Research through Contract Nos. N000-14-94-10346 and N000-14-90-J-1719.
    Keywords: Mooring technology ; Data telemetry ; Inductive modem
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: 7032929 bytes
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  • 8
    Publication Date: 2022-05-26
    Description: A real-time tomography system has been developed which combines ocean acoustic tomography with satellite-based time keeping and satellite telemetry. The basis of the system is the acoustic tomography transceiver and its associated acoustic navigation grid. To this basic system, a link to the surface has been added to provide a pathway for telemetry of the tomographic data to shore and a downlink for satellite-derived time which is used to correct the transceiver's clock. The surface buoy contains a GPS receiver, clock comparator, system controller and multiple ID Argos transmitters. Processed tomography signals, transceiver location data time, time drift and surface buoy engineering data are transmitted to satellite using a total of 32 data buffers transmitted every eight minutes. The report describes the real-time tomography system in detail, with particular emphasis on the modifications implemented to convert the standard tomography instrument to a real-time oceanographic tool.
    Description: Funding was provided by the Office of Naval Technology under Contract No. N000-14-C-90-0098.
    Keywords: Acoustic tomography ; Real-time ; Telemetry
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: 5194011 bytes
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  • 9
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: The Advanced Engineering Laboratory of the Woods Hole Oceanographic Institution is a development laboratory within the Applied Ocean Physics and Engineering Department. Its function is the development of oceanographic instrumentation to test developing theories in ocean physics, and to enhance current research projects in other disciplines within the oceanographic community. This report summarizes recent and ongoing projects performed by members of the laboratory.
    Keywords: Advanced Engineering Laboratory ; Electronic systems ; Oceanographic instrumentation
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: 3195207 bytes
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  • 10
    Publication Date: 2022-05-26
    Description: A system concept has been developed by Viasat, Inc. and Woods Hole Oceanographic Institution for improving the data telemetry bandwidth available on ocean buoys. This concept utilizes existing communications satellites as data relay stations and mechanically steered antenna arrays to achieve increased data rates and improved power efficiency needed for ocean applications. This report describes an initial feasibility and design study to determine if a mechanically steered antenna array can meet the requirements of open ocean buoy applications. To meet the system requirements, an 18-element microstrip antenna (9-element transmit, 9-element receive) was designed and fabricated under subcontract by Seavey Engineering Associates, Inc. It operates in the 4-6GHz frequency band (C-band) and provides 14 dB of gain. The 1/2 power beamwidth is +-t5° in azimuth and elevation. This antenna design, in conjunction with a simple rotating mount, was used to evaluate the potential of this approach to keep a geostationary satellite in view when mounted on an ocean buoy. The evaluation is based on laboratory measurements using a magnetic compass and a small stepper motor to maintain antenna orientation while the complete assembly was rotated and tilted at speeds similar to what would be expected on an offshore buoy equipped with a stabilizing wind vane. The results are promising, but less than conclusive because of limitations in the experimental test setup. The recent introduction of several commercially available mechanically steered antennas designed for use on small boats may provide a viable alternative to the approach described here with appropriate modification to operate at C-band.
    Description: Funding was provided by Viasat, Inc., under subcontract No. SC95001 and by a Cecil H. and Ida M. Green Technology Innovation Award.
    Keywords: Ocean data telemetry ; Directional antenna ; Satellite telemetry
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: 5311725 bytes
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