A SAIL compatible three channel acoustic navigation interrogator

Ocean Acoustic Tomography data are significantly degraded if mooring motion is unknown. An autonomous instrument employing a solid state data logger designed to track and record mooring motion is described. Navigation is accomplished by simultaneously interrogating each of three bottom mounted transponders positioned in an equilateral triangle around the mooring's anchor at a range approximately equal to the depth of the tracked instrument. The three round-trip travel times thus obtained having a resolution of 125uS and a SNR dependent jitter of less than 1.5mS, define a unique instrument position and are recorded along with the time of day and day of year. The measurement period, the system clock and the program start time are set via a 20mA SAIL. Since the standby power requirement is negligible compared to the battery capacity, the instrument may be programmed months in advance of the deployment. System endurance varies with the measurement period, however, typical programs permit navigation for up to 21 months at 12 points per day. Upon recovery, the navigator data may be down-loaded via SAIL directly to the storage medium of a suitable computer.Funding was provided by the Office of Naval Research under Contract Nos. N00014-82-C-0152 and N00014-85-C-0379

WHOI SDSL data-link project—ethernet telemetry through sea cables

Author Posting. © American Meteorological Society, 2017. 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 Atmospheric and Oceanic Technology 34 (2017): 269-275, doi:10.1175/JTECH-D-11-00196.1.A data telemetry technique for communicating over standard oceanographic sea cables that achieves a nearly 100-fold increase in bandwidth as compared to traditional systems has been recently developed and successfully used at sea on board two Research Vessel (R/V) Atlantis cruises with an 8.5-km, 0.322-in.-diameter three-conductor sea cable. The system uses commercially available modules to provide Ethernet connectivity through existing sea cables, linking serial and video underwater instrumentation to the shipboard user. The new method applies Synchronous Digital Subscriber Line (SDSL) communications technology to undersea applications, greatly increasing the opportunities to use scientific instrumentation from existing ships and sea cables at minimal cost and without modification.This development program has been supported, in part, through research grants from the National Science Foundation (OCE 0447395), the National Aeronautics and Space Administration’s ASTEP program (NNX09AB76G), and a WHOI Green and Hiam Innovative Technology Award.2017-07-2

Real-time tomography mooring

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.Funding was provided by the Office of Naval Technology under Contract No. N000-14-C-90-0098

Preliminary acoustic and oceanographic observations from the ASIAEX 2001 South China Sea Experiment

The Asian Seas International Experiment (ASIAEX) was a very successful scientific collaboration between the United States of America (USA), the People’s Republic of China (PRC), Taiwan (ROC), the Republic of Korea (ROK), Japan, Russia, and Singapore. Preliminary field experiments associated with ASIAEX began in spring of 2000. The main experiments were performed in April-August, 2001. The scientific plan called for two major acoustics experiments, the first a bottom interaction experiment in the East China Sea (ECS) and the second a volume interaction experiment in the South China Sea (SCS). In addition to the acoustics efforts, there were also extremely strong physical oceanography and geology and geophysics components to the experiments. This report will concentrate on describing the moored component of the South China Sea portion of ASIAEX 2001 performed from the Taiwan Fisheries research vessel FR1 (Fisheries Researcher 1). Information on the environmental moorings deployed from the Taiwanese oceanographic research vessel OR1 (Oceanographic Researcher 1) will also be listed here for completeness, so that the reader can pursue later analyses of the data. This report does not pursue any data analyses per se.Funding was provided by the Office of Naval Research under Grant Numbers N00014-01-1-0772, N00014-98-1-0413 and N00014-00-1-0206

User needs elicitation via analytic hierarchy process (AHP). A case study on a Computed Tomography (CT) scanner

Background: The rigorous elicitation of user needs is a crucial step for both medical device design and purchasing. However, user needs elicitation is often based on qualitative methods whose findings can be difficult to integrate into medical decision-making. This paper describes the application of AHP to elicit user needs for a new CT scanner for use in a public hospital. Methods: AHP was used to design a hierarchy of 12 needs for a new CT scanner, grouped into 4 homogenous categories, and to prepare a paper questionnaire to investigate the relative priorities of these. The questionnaire was completed by 5 senior clinicians working in a variety of clinical specialisations and departments in the same Italian public hospital. Results: Although safety and performance were considered the most important issues, user needs changed according to clinical scenario. For elective surgery, the five most important needs were: spatial resolution, processing software, radiation dose, patient monitoring, and contrast medium. For emergency, the top five most important needs were: patient monitoring, radiation dose, contrast medium control, speed run, spatial resolution. Conclusions: AHP effectively supported user need elicitation, helping to develop an analytic and intelligible framework of decision-making. User needs varied according to working scenario (elective versus emergency medicine) more than clinical specialization. This method should be considered by practitioners involved in decisions about new medical technology, whether that be during device design or before deciding whether to allocate budgets for new medical devices according to clinical functions or according to hospital department

Acoustic and oceanographic observations and configuration information for the WHOI moorings from the SW06 experiment

This document describes data, sensors, and other useful information pertaining to the moorings that were deployed from the R/V Knorr from July 24th to August 4th, 2006 in support of the SW06 experiment. The SW06 experiment was a large, multi-disciplinary effort performed 100 miles east of the New Jersey coast. A total of 62 acoustic and oceanographic moorings were deployed and recovered. The moorings were deployed in a “T” geometry to create an along-shelf path along the 80 meter isobath and an across-shelf path starting at 600 meters depth and going shoreward to a depth of 60 meters. A cluster of moorings was placed at the intersection of the two paths to create a dense sensor-populated area to measure a 3-dimensional physical oceanography. Environmental moorings were deployed along both along-shelf and across-shelf paths to measure the physical oceanography along those paths. Moorings with acoustic sources were placed at the outer ends of the “T” to propagate various signals along these paths. Five single hydrophone receivers were positioned on the across shelf path and a vertical and horizontal hydrophone array was positioned at the intersection of the “T” to get receptions from all the acoustics assets that were used during SW06.Funding was provided by the Office of Naval Research under Contract No. N00014-04-1014

Atlantic Long-Term Oceanographic Mooring (ALTOMOOR)

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.Funding was provided by the Office of Naval Research through Contract Nos. N000-14-94-10346 and N000-14-90-J-1719