Advanced Engineering Laboratory project summaries 1992

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

Advanced Engineering Lab project summaries 1991

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

Advanced Engineering Laboratory project summaries : 1995-1996

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

Advanced Engineering Laboratory project summaries 1994

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

Performance of a new generation of acoustic current meters

Author Posting. © American Meteorological Society, 2007. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 37 (2007): 148–161, doi:10.1175/JPO3003.1.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.This material is based upon work supported by the National Science Foundation under Grant 9810641

Expendable oceanographic mooring (XMOOR)

An expendable, self-deploying mooring (XMOOR) for shallow water applications has been developed to address Navy requirements for environmental monitoring. The project has been conducted jointly between the Woods Hole Oceanographic Institution and the Naval Research Laboratory at Stennis, MS. WHOI has taken the lead on the mechanical design of the system while NR has developed the electronics. Eight prototype XMOOR systems have been built. They are designed for water depths between 10 and 100m, for deployments of up to 3-months duration, and for automatic deployment. Their sensor suite includes barometrc pressure, air temperatue, water temperature at up to 25 levels, and conductivity and pressure at up to 3 levels. Data telemetry is accomplished via the Argos DCS and by line-of-sight VH confguration of the data collection program. This report describes the XMOOR mechanical system. The data collection and telemetry systems are described separately in (1) and (2).Funding was provided by the Office of Naval Research through Contract Nos. NOOO-14-92-C-6028 and NOOO-14-95-1-0774

Advanced Engineering Laboratory project summaries 1989

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

Design and evaluation of a directional antenna for ocean buoys

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.Funding was provided by Viasat, Inc., under subcontract No. SC95001 and by a Cecil H. and Ida M. Green Technology Innovation Award

Feasibility study of non-invasive telemetry techniques for use with submarine telephone cables

The feasibility of using inductive coupling with existing submarine telephone cables for telemetry of data from ocean sensors was investigated. The submarine telephone cable was simulated with a computer model and the model results were tested experimentally by deploying 600 meters of coax cable in Woods Hole Harbor. In parallel a study of the optimum access methods and modulation and techniques was performed. Results of the feasibility study showed that a non-invasive technique for inductive coupling is not feasible for use with existing SF and SD coaxial cable designs. Signals induced in both conductors by a toroid encircling the cable remain identical as they propagate along the cable as a result of mutual inductance. Thus, no signals are apparent at the repeaters. Optimal use of cable bandwidth combines time division multiple access with trellis-coded QAM modulation.Funding was provided by the IRIS Consortium under sub-award agreement No. 0169 and by the W.M. Keck Foundation through their Technology Innovation Awards

ESOM I and II final report

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.Funding was provided by the Office of Naval Research under Contract No. N00014-90-J-1719