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  • Underwater acoustics  (45)
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  • Woods Hole Oceanographic Institution  (46)
  • 1
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-11-18
    Description: In the fall of 1967 an extended program of tests was begun to evaluate several types of acoustic anchor release devices available on the market. This program was.prompted by a.need to isolate and correct problems which came to light after, several years of use of the O.R.E. system. Two other systems, one made by Raytheon and the other by American Machine and Foundry Co., were tested. This report deals with previous use of O.R.E.'s system by the W.H.O.I. Buoy Project and the testing program in 1968 and with the Raytheon and A.M.F. test series. Detailed description of these systems and their operation will not be undertaken in this report. Reference is made to data published by the respective manufacturers.
    Description: Submitted to the Office of Naval Research under Contract N00014-66-C0241, NR 083-004.
    Keywords: Underwater acoustics ; Oceanographic instruments
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 2
    Publication Date: 2022-05-25
    Description: Digital computing techniques have been used in special computing applications in underwater acoustics at WHOI for many years, but recently we have commenced intensive application of digital data handling and computing facilities to a variety of computing, data storage, and data handling problems. Progress in these applications is described under Acoustic Instrumentation below. Some bathymetric studies carried out recently under another contract have shown that even very narrow-beam, single-beam echo sounders simply cannot provide reliable depth sounding information where the topography is complex. In this work we have been experimenting with the inverted echo sounder, discussed below, originally developed to measure depth of the sound velocimeter. The inverted echo sounder is lowered to a position within a few feet of the bottom. The total acoustic travel time from surface to bottom may be read as the sum of the travel times from the instrument to the bottom and surface . True depth is then computed in the usual way with appropriate s cnmd velocity data. In its present form the inverted echo sounder is suitable for mapping ~mall areas~ a few square miles, provided there is a suitable means of positioning the instrument. We have experimented with radio-acoustic navigation, and intend to experiment with vertical triangulation from the suspending ship as well. Steady demands for new, modified, and improved instrumentation have been responded to in echo sounding, seismic profiling, and spectrum analysis, as detailed below.
    Description: Undersea Warfare Branch Office of Naval Research Under Contracts Nonr-1367(00)NR261-102 and Nonr-2129(00)NR261-104
    Keywords: Underwater acoustics ; Oceanographic instruments
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    Type: Technical Report
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  • 3
    Publication Date: 2022-05-25
    Description: This i s a status report for the period 1 May 1966 to 31 October 1966 for Contract Nonr - 4029 with the Office of Naval Research. Subjects of this contract are in Oceanic Acoustics, Physical Oceanography, Sea Floor Properties and Advisory Activities. Preliminary results of a cruise by CHAIN to the Mediterranean and the Red Sea during the summer of 1966 are given. Sound-velocity and temperature structure south of Bermuda as observed from ATLANTIS II (June, July 1966) are described. Continuing analysis of acoustical and geophysical data is discussed. Papers, reports, and technical memoranda written during this period are listed.
    Description: The Undersea Warfare Branch., Office of Naval Research., under Contract.Nonr-4029(00) NR 260-101.
    Keywords: Underwater acoustics
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 4
    Publication Date: 2022-05-25
    Description: This is a report of the research program under contracts Nonr-4029 (1 May - 31 October 1963), and Nonr-3243 (1 May - 31 October 1963} . Both contracts are with the Office of Naval Research, Code 466. Contract Nonr-4029 is a continuation of Contract Nonr-1367. Under Contract Nonr-4029, ATLANTIS· II and CHAIN, in May and August, were employed in searching for the sunken submarine THRESHER by various means. Under the same contract, activities were devoted also to the development of systems or components of systems for search and for navigational control required in such operations. One system of submerged navigation was employed for locating suspended instruments by acoustic ranging from the ship. A second navigation system was also tested which depends on acoustic ranging either from the ship or from the suspended instrument to a hydrophone buoyed near the bottom. This hydrophone is connected to a radio link in a surface buoy. This system will be useful not only for navigation but also for bottom reflection studies. A program has been started to print and mount all photos taken by WHOI on the THRESHER search; it will be coordinated with other similar efforts in the continuing investigation of the disaster. Under Contracts Nonr-4029 and Nonr-3243 considerable progress has been made in other research, which is described in this report .
    Description: Submitted to Under sea Warfare Branch Office of Naval Research Under· Contracts Nonr- 4029(00)NR261-10 2 and Nonr- 3243(00) NR261-136
    Keywords: Submarine geology ; Underwater acoustics ; Oceanographic instruments
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  • 5
    Publication Date: 2022-05-25
    Description: This is a report of activities supported under Contract NObsr-72521 for the period 1 January through 31 March 1961. It also contains mention of other reports, papers, and undertakings of the submarine geophysics group (listed under "Personnel") which are believed to be of interest to the Bureau of Ships. During this period no cruises have been supported directly under this contract. Eight members of the group under the leadership of Dr. Voorhis have participated in a cruise of CHAIN to the Romanche Trench. Their principal objective was to determine the sill depth which controls the exchange of deep, cold water ,between the western and eastern sides of the Atlantic Ocean. This sill was previously identified from hydrographic evidence to lie somewhat east of the Romanche Trench. A second objective was to continue the observations of temperature structure near the sea's surface with the thermistor chain. Another group, under Mr. Baxter's leadership, continued a sound transmission study in the Bermuda area in support of Project ARTEMIS. A third group, under Dr. Hays's direction, commenced a finely detailed bathymetric survey of an area of special interest to Project ARTEMIS. In all three of these studies we are making use of one or more experimental techniques in the use of sonobuoys, underwater acoustic navigation for submerged instruments, and sound coherence studies which are planned for use eventually in sound transmission and bottom reflection research under this contract.
    Description: Bureau of Ships Under Contract NObsr-72521
    Keywords: Sonar ; Underwater acoustics ; Submarine geology
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  • 6
    Publication Date: 2022-05-26
    Description: Research at sea during this three month period, supported by Contract NObsr-72521, was carried out mostly during the latter portion of the CHAIN Cruise 21 to the eastern Mediterranean. Near-surface sound transmission runs were made with the aid of two foreign ships in the eastern Mediterranean and Tyrrhenian Sea. Sound velocity measurements were made there also. Reverberation and back-scatter measurements using half pound explosives as sound sources were recorded on magnetic tape for future analysis. Further, at several places during the cruise acoustic reflectivity of the sea-floor was measured by means of a semi-automatic system employing the Precision Graphic Recorder and the Edo UQN Echo Sounder. Research other than that on CHAIN Cruise 21, included ambient noise studies of recorded signals from finback whales, and analysis of data from previous observations at sea.
    Description: The Bureau of Ships Under Contract NObsr - 72521
    Keywords: Sonar ; Underwater acoustics ; Submarine geology
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  • 7
    Publication Date: 2022-05-26
    Description: Geophysical investigations were carried out aboard R /V CHAIN in the Indian Ocean, the Mediterranean Sea, and the North Atlantic Ocean. Observations underway were continuous seismic profiling, gravity, magnetic, and echo sounding measurements. At stations rocks were dredged, cores were taken (about 10 meters long, photographic montages of the sea floor were made, and the sound velocity of the water was measured as a function of depth. Progress is being made in filtering and correlation techniques for seismic profiling, while seismic receiving arrays were improved to make them quieter. The analysis of internal wave data is continuing, but further observations at sea will be required in order to fully understand the mechanism of propagation. Seven papers were published during this period and thirteen were submitted for publication. These papers are concerned with seismic profiling, seismic refraction profiles, sediment ponding, sound transmission, thermal fronts, and biological papers dealing with sound production by marine mammals and deep-sea fish natural history gained from bottom photographs. A new thermistor string intended to replace and improve upon the original thermistor chain was the principal new instrumental development.
    Description: Undersea Warfare Branch Office of Naval Research under Contracts Nonr-4029(00)NR260-101 and Nonr-3243(00)NR260-108
    Keywords: Submarine geology ; Underwater acoustics ; Oceanographic instruments
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  • 8
    Publication Date: 2022-05-26
    Description: Experiments are described to demonstrate a new method of sonic signalling at extremely long ranges in the oceans, utilizing the natural sound channel. Signals were made by causing a four pound charge of TNT to explode at about 4000 feet depth. These signals have the following qualities: (a) Extremely long range transmission (probably 10,000 miles). (b) Signal is positively identifiable. (c) Abrupt termination of the signal allows the arrival time to be read with an accuracy better than l/20th second. This permits location of source to better than a mile, if the signal is received at three suitably located stations. (d) The signal duration is related in such a way to the distance that the distance may be estimated to 30 miles in 1000 from reception at a single station. The limitations are: (a) It is required that the great circle path which the sound follows between source and receiver lie entirely in deep water (probably at least 1000 fathoms). (b) Sound travels in water at a speed of roughly 1 mile per second so that the interval between the origin of the signal and its reception becomes sufficiently great to be a handicap for some uses, particularly with aircraft. The signals were received to distances up to 900 miles. Two receiving arrangements have been used, a hydrophone hung 4000 feet over the side of a ship which was hove to, and a shore connected. hydrophone which lay on bottom 4000 feet deep. Extrapolation of the results indicate a range of at least 10,000 miles from this size charge. Recommendation is made to utilize a network of monitoring stations to locate planes, ships, and life rafts in distress on the open oceans. Three or more stations receiving a signal could locate the source better than one mile.
    Description: Con tract NObs - 2083, Formerly OEM: sr - 31
    Keywords: Underwater acoustics ; Sonar
    Repository Name: Woods Hole Open Access Server
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  • 9
    Publication Date: 2022-05-26
    Description: This is a progress report of the Institution's research between April and 30 June 1961 supported under Contract NObsr-72521 with the Bureau of Ships, Navy Department. The program consists of studies of compressional wave transmission (sound and seismic waves) through sea water and the underlying earth's crust, the ambient noise of the ocean, and the scattering of sound in the sea and beneath the ocean floor. During the present reporting period sound transmission studies have included laboratory analysis of data taken previously in a continuing program directed toward describing near-surface transmission into the shadow zone, and toward accounting for the variability of near-surface . transmission under nominally "good" sonar conditions . Seismic studies consisted of analysis of seismic refraction data taken two years ago in: the Mediterranean, completion of a report of a seismic reflection study of the southern part of Narragansett Bay, extension of this latter study into Rhode Island Sound, and a series of new measurements of the apparent reflectivity of the bottom at 12 kcps. In the sound-scattering program we accepted delivery of a small towed fish containing sound gear for scattering experiments over near-horizontal paths. This instrument was taken to sea on CHAIN for initial testing and self-noise measurements. A series of tests of new sound sources, supported under Contract Nonr-1367, have demonstrated that seismic reflection observations can be made in deep ocean basins from a ship underway slowly using only such electrically-powered sources as Thumper or Sparker. Sub-bottom structures have been mapped in fine detail experimentally in water over 2600 fathoms deep. This work was done with a Thumper having a 5000-joule electrical input . Plans have been made for increasing the electrical input of Thumper to about 13, 000 joules and Sparker to 25, 000 joules. We plan to use these new sound sources in sound transmission experiments this summer and fall in the Mediterranean Sea. As an extra-curricular hobby Miss Broughton, a technical assistant at the Institution, made interesting magnetic tape recordings of the sounds of a small pilot whale stranded on a local beach. She held microphones on the whale's head near the blow hole. The recorded sounds are rather different from those heard through the water near pilot whales. These and other parts of our work are detailed below.
    Description: Bureau of Ships Under Contract NObsr-72521
    Keywords: Sonar ; Underwater acoustics ; Submarine geology
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  • 10
    Publication Date: 2022-05-26
    Description: This is a status report for the six-month's period indicated. It includes the closing phase of a long cruise of CHAIN to the Mediterranean Sea during which circulation of the waters of the eastern Mediterranean were studied and sound transmission, seismic reflection, and shallow thermal structure measurements were made at various places in the Mediterranean and the North Atlantic. During the remainder of the period various geophysical, geological, and hydroacoustical analyses were conducted at Woods Hole and preparations for the summer cruising season were made.
    Description: The Undersea Warfare Branch Office of Naval Research Under Contracts Nonr - 1367 (OO)NR261-102 and Nonr-2129(00)NR261-104
    Keywords: Underwater acoustics
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  • 11
    Publication Date: 2022-05-26
    Description: Research during this six month period was performed during cruises of the CHAIN to the Romanche Trench, to the Puerto Rico Trench, and to the Mediterranean Sea, and during a cruise of the BEAR to the Gulf of Maine. New instrumentation aboard the CHAIN included the 12, 000 joule Boomer and a 25, 000 joule Sparker for continuous Seismic reflection profiles and other research in hydroacoustics. A semiautomatic data recording system for shipboard use was in.stalled and operated by IBM and, to facilitate launching and retrieving deep gear, a closed circuit television system was used . Also the navigational system, GEON, was installed and tested. Prior to the cruises of the summer and fall redesign and refinement of the instrumentation and equipment entailed overhaul of the thermistor chain and contouring temperature recorder, modification of the heat probe for thermal gradient measurements to lessen lowering time, and improvement of the inverted echo-sounding equipment. Research at sea included collecting samples of rock and sediment and photographing the ocean floor in support of research into the structure and dynamics of the Romanche and Puerto Rico Trenches and the Mid-Atlantic Ridge , observing internal waves in the North Atlantic studying water circulation in the Mediterranean, the dynamics of flow through the Strait of Gibraltar (concentrating this year on internal waves there), observing the behavior and measuring the sound scattering properties of deep scattering layers in the Mediterranean, measuring heat flow from the inner Earth across the Mid-Atlantic Ridge and in the western Mediterranean, and studying the relationship between sound transmission and the physical properties of the water and sea floor in the eastern Mediterranean. At Woods Hole various analysis programs progressed. Several of these used programs of digital computing which have been prepared lately at Woods Hole. The precision time source for remote control reported earlier was improved and tested ashore. A tape recording system for Scuba divers was devised and tested satisfactorily in thirty feet of water.
    Description: Undersea Warfare Branch Office of Naval Research Contracts Nonr-1367(00)NR 261-102 and Nonr-2129(00)NR 261-104
    Keywords: Underwater acoustics
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  • 12
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    Woods Hole Oceanographic Institution | Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: Measurements of the acoustic pressure of spark discharges were made at a shallow depth (10 feet) for various voltages, stored energies, inductances and capacitances of the system, and electrode areas. The voltages ranged from 1500 V to 11 KV, and the energy storing capacitances from 8 to 800 ufd. In this range the peak pressure observed was proportional to peak current and the decay constant of the pressure-time curve was essentially the same as the electrical discharge decay constant.
    Description: Office of Naval Research under Contract Nonr 1 367(00) NR 261-103
    Keywords: Sound pressure ; Underwater acoustics
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  • 13
    Publication Date: 2022-05-26
    Description: This progress report contains findings in 1) physical oceanography, 2) marine biology, 3) geology and geophysics, and 4) hydroacoustics. 1) Long-period internal waves are deduced from sound-velocity data between Bermuda and the Antilles . The region of the thermal front (usually found near 30°N) was thought on one occasion to be a generator of internal waves. 2) Midwater fishes were four times more abundant north of the front than south and midwater reverberation levels varied similarly. 3) Evidence obtained southeast of Charleston, S.C. shows that the continental shelf has been building out over the Blake Plateau. The gravity characteristics of many major rifts of the world reveal that as the width of the rift increases, the Bouguer anomalies become increasingly positive. 4) Observations support the hypothesis that diffraction effects are required to explain the sound propagation in convergence zones in the Mediterranean. A major engineering accomplishment was the installation and use of Sea Spider on the Blake Plateau. Sea Spider is a near motionless platform for scientific measurements in the deep ocean. The development of an automatic digital depth-reading system for use with echo sounders on ships were successfully completed, improvements in seismic profiling techniques were made, and special coherency studies of towed hydrophone array noise have progressed.
    Description: Undersea Warfare Branch Office of Naval Re search under Contract Nonr-4029(00) NR 260-101
    Keywords: Submarine geology ; Underwater acoustics ; Oceanographic instruments ; Blake Plateau
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  • 14
    Publication Date: 2022-05-26
    Description: The work sponsored by ARPA at Woods Hole Oceanographic Institution is having an impact on efforts by those not directly involved in the projects both within and without the Institution. The navigation system being developed for submersible/mother ship has been recognized as a very useful system by members of the Geology/Geophysics Department and the Department of Physical Oceanography. Each department is now developing their own system based on the work already completed by the Ocean Engineering Department under the ARPA contact. Through the ARPA contract ComPhibLant (specifically ComPhibRonTen) was shown some of the advantages of doing something new about small boat and heavy object handling at sea and this program is expected to have some direct effect upon methods they will use in the future. Although the project concerned with developing biological equipment for deep sea work has not continued as part of the ARPA program, the seed was succssfully sown and several items are being developed at the Institution under separate funding. All the projects continued at a fair pace but not without some problems. The Deep Sea Rock Drill had some minor setbacks during operations with ALVIN, and the Air-Sea System (Long Range Ech-Ranging) project was hampered by a faulty engine aboard the air craft. Summaries of progress are given immediately below and more detail is available in the individual reports further on.
    Description: Prepared for the Office of Naval Research under Contract N00014-71-C00284; NR 293-008.
    Keywords: Oceanographic submersibles ; Oceanographic buoys ; Submarine geology ; Underwater acoustics ; Sonar
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  • 15
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: High frequency acoustic backscattering systems are being used in monostatic modes to evaluate the use of acoustic techniques to detect and study a variety of fluid processes in the oceanic environment. A short outline of those research programs actively evaluating and using acoustic techniques is presented, followed by a detailed review of this investigator's program. This program uses a multifrequency high frequency acoustic system to study a variety of processes including turbulent mixing, air-sea interactions, internal waves, interleaving water masses, natural particulate dispersion and distribution, the dispersion of particulates associated with deep ocean disposal of industrial chemical waste, and biological response to a variety of stimulae including fluid motion, predators, and oceanographic instrumentation. Graphic acoustic data records of several of the above phenomena are described.
    Description: Prepared for the Office of Naval Research under Contract N00014-77-C-0196; NR 083-004, for the National Oceanic & Atmospheric Administration under Grants NA79AA-D-00030 (Ocean Dumping Program) and NA79AA-D-00102 (Office of Sea Grant) and for the National Science Foundation under Grant OCE 77-08682.
    Keywords: Underwater acoustics ; Oceanography ; Marine biology
    Repository Name: Woods Hole Open Access Server
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  • 16
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: Originally issued as Reference No. 66-10, series later renamed WHOI-
    Description: It is suggested in this report that the intensity of midwater sound-scattering in the ocean varies from point to point as the abundance of marine life varies. Several charts depicting variations in the abundance of marine life are given, from which estimates of the intensity of sound-scattering can be made.
    Description: Submitted to the Offiae of Naval Researah under Contraat Nonr-4029(00JNR 260-101.
    Keywords: Echo scattering layers ; Underwater acoustics
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  • 17
    Publication Date: 2022-05-26
    Description: Also published as: Journal of the Acoustical Society of America 68 (1980): 1750-1767
    Description: Acoustical signals at 270 Hz from SOFAR floats drifting in the region southeast of the Gulf Stream were recorded during most of 1975 from a near axis sound channel hydrophone near Bermuda. The amplitude levels received exhibit a large increase (12–18 dB) commencing about 24 July, following a long period (March to July) of relatively lower peak level amplitudes. A major part of the increase can be attributed to the influence of a large cyclonic eddy (Gulf Stream ring) that passed slowly between the SOFAR floats and Bermuda. Such an eddy produces a large sound speed anomaly that extends to depths below the axis of the sound channel. On 24 July, two SOFAR floats were known to have approximately the same sound transmission path through the edge of the large eddy. The sound transmission peaks occur when no ocean eddy is between the SOFAR floats and the receiver. Their spacing shows they occur at regular refraction caustics in the sound channel. When the sound transmission path passes through an eddy, these transmission focal distances are shifted to greater range and the signal level may be greatly enhanced. The decrease of caustic peak intensities with range is 5 dB per double distance, and this agrees with theory. Several different levels of peak acoustic intensity occur and these result from two float depths and oceanic thermocline oscillations.
    Description: Prepared for the Office of Naval Research under Contract N00014-74-C-0262; NR 083-004·.
    Keywords: Underwater acoustics ; Eddies
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  • 18
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: Also published as: Journal of the Acoustical Society of America 69 (1981): 982-988
    Description: A phase-coded signal with 64-ms resolution was transmitted at 10-min intervals for a 19-day period over two ~300-km ranges. The acoustic source was moored at 2000-m depth northwest of Bermuda. One receiver was moored at 2000-m depth to the northeast of the source and the other receiver was bottom mounted at ~1000- m depth near Bermuda. The large (~0.6 s) travel time change at the Bermuda receiver is probably due in large part to motion of the source mooring in the presence of currents. The multipath arrival pattern at the moored receiver undergoes significant modification due to the presence of a southern meander of the Gulf Stream which intersects this transmission path.
    Description: Prepared for the Office of Naval Research under Contract N00014-77-C-0196 and NORDA contract N00014-79-C-0071.
    Keywords: Underwater acoustics
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  • 19
    Publication Date: 2022-05-26
    Description: The system described provides wide operational flexibility at any operating frequency from 5 kHz to over 800 kHz (except for a small band around 455 kHz) limited mainly by the availability of transducers. Variable pulse width, variable receiver bandwidth, low receiver noise, various time variable gain functions and wide system dynamic range characterized the system. Built-in time-sharing controls maximize flexibility of graphics display on either dry-paper or fibre-optic CRT recorders.
    Description: Prepared for the NORDA under Contract N00014-77-C-0196; and for the National Oceanic and Atmospheric Administration under Grant 04-8-MO1-43.
    Keywords: Underwater acoustics ; Sonar ; Oceanographic instruments ; Scientific apparatus and instruments
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  • 20
    Publication Date: 2022-05-26
    Description: Also published as Journal of Geophysical Research, Vol. 83, No. C8, 1978, pp. 4062-4068
    Description: Acoustic data, transmissometer data, and calculations are presented which indicate that high-frequency acoustic backscattering systems can become a valuable tool in the remote monitoring of suspended particle distributions and active resuspension areas. Data are also presented which show that acoustic backscattering systems can be used to remotely detect slope/shelf water frontal zones. Towed acoustic systems should be able to map the extent of the frontal zone and add significantly to the understanding of frontal zone processes.
    Description: Prepared for the Naval Oceanic Research and Development Activity under Contract N00014-77-C-0196.
    Keywords: Underwater acoustics ; Oceanographic instruments
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  • 21
    Publication Date: 2022-05-26
    Description: Also published as: Journal of Geophysical Research 85 (1980): 3759-3777
    Description: A detailed seismic refraction experiment was carried out across the Kane Fracture Zone near 24°N, 44°W using explosive and air gun sound sources and eight ocean bottom hydrophone receivers. The shooting lines and receive rs formed a 'T' configuration across the fracture zone, with two receivers located about SO km apart in the fracture zone trough and the remaining six receivers positioned 25-30 km apart on either side of the fracture zone. The crustal thicknesses and velocities observed at the receivers located north and south of the Kane Fracture Zone fall within the range of those typically observed for normal oceanic crust. There is no convincing evidence for signficantly different crustal thicknesses or upper mantle velocities on either side of the fracture zone despite a 10-m.y. age difference. Anomalously thin crust is present beneath the Kane Fracture Zone trough with total crustal thicknesses of only 2-3 km, about half the thickness of normal oceanic crust. This crust is also characterized seismically by low compressional wave velocities (~4.0 km/s) at shallow depths and the absence of a normal layer 3 refractor. This anomalous crust extends over a width of a t least 10 km. Dense, high-velocity mantle type material may also exist at shallow depths beneath the adjacent Kane Fracture Zone ridge. Results from other geological and geophysical studies of fracture zones suggest that this type of crustal structure may by typical of many Atlantic fracture zones. We propose that the anomalously thin crust found within these fracture zones is a primary feature caused by the accretion of a thinner volcanic and plutonic layer within the fracture zone. This anomalous crust, which probably is restricted to a zone no wider than a typical transform fault valley (~10 km) in most cases, is inferred to consist of a few hundred meters of extrusive basalts and dikes overlying about 2 km of gabbro and metagabbro, possibly interbedded with ultramafics. This anomalously thin crustal section may be extensively fractured and brecciated at shallow levels by faulting in the active transform domain. A relatively narrow zone of thin crust within fracture zones can ex plain a number of geological and geophysical characteristics of fracture zones including the depth of the transform fault valley and the exposure of deep crustal and upper mantle rocks in the walls of fracture zones.
    Description: Prepared for the Office of Naval Research under Contract N00014-74-C0262 NR083-004.
    Keywords: Seismic refraction method ; Underwater acoustics
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  • 22
    Publication Date: 2022-05-26
    Description: During July and August of 1980 near surface water velocities of Lake Huron were measured by tracking drogues, equipped with sonobuoys, using an acoustic travel time technique. Prior to these experiments difficulties associated with acoustic ray bending in the shallow, highly stratified environment were anticipated. Simple models were developed to predict the errors in drogue position and velocity determination resulting from ray bending. During the experiments round trip travel times of acoustic pulses transmitted between three bottom transponders and a transducer (lowered from a ship) were recorded. These combined with ray diagrams strongly suggested that, for a separation between the transducer and a bottom transponder of about 1.2 km, pulses which were detected first traveled by two paths, that of an inflected ray and that of a ray trapped beneath the thermocline. The error in position and velocity determination associated with these paths was 1 to 2%. Evidence also indicated that increased thermocline depth resulted in decreased tracking range.
    Description: Prepared for the Department of Energy under Contract DE-AC02-79EV10005 and for NOAA under Contract 03-5-022-26.
    Keywords: Underwater acoustics ; Acoustic drogue measurements
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  • 23
    Publication Date: 2022-05-26
    Description: Also published as: Journal of the Acoustical Society of America 68 (1980): 1376-1390
    Description: Seventeen piston cores up to 13 m long were recovered from representative acoustic and lithologic environments of the Hatteras and Nares Abyssal Plains in the western North Atlantic. Compressional-wave velocities (corrected to in situ conditions) and bulk physical properties measured on the cores are used to characterize the acoustic framework of these areas. For correlation with conventional seismic data, wholecore averages of properties are a better index to the acoustic nature of abyssal plain sediments than properties of the upper few centimeters of the seafloor because (I) strong changes in lithofacies (and acoustic properties) occur over depth scales of tens of centimeters to meters in the sediment column, and (2) conventional seismic frequencies of 3.5 kHz or less sample these variations to subbottom depths of tens of meters and more. Wholecore properties are a function of the thickness and distribution of high-velocity silt and sand layers in the core; they vary in a complex fashion with proximity to the source of turbidity currents, distance from axial paths of turbidity-current flows, local and regional basin geometry, and seafloor slope. Thus strongly reflective seabed regions with numerous high-velocity layers are not restricted simply to near-source areas nor are weakly reflective seabed regions (clay sediments only) limited to "distal" areas. Whole-core properties show a good qualitative correlation to variations in 3.5-kHz reflection profiles, and 3.5-kHz echo character therefore provides a useful means of mapping general acoustic properties over large regions of abyssal plains.
    Description: Prepared for the Office of Naval Research under Contracts N00014-75-C-0210 and N00014-79-C-0071; NR 083-004.
    Keywords: Underwater acoustics ; Marine sediments
    Repository Name: Woods Hole Open Access Server
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  • 24
    Publication Date: 2022-05-26
    Description: Also published in: Proceedings of the 8th International Colloquium on Ocean Hydrodynamics
    Description: The techniques of flow measurement which have been successful in laboratory studies of boundary layer turbulence are difficult to use in the ocean; and the current meters penerally used in the ocean are not suited to measuring bottom boundary layer flow . A suitable sensor for bottom turbulence measurements should measure vector components, respond linearly to these components, maintain an accurate zero point, disturb the flow negligibly or in a well predicted way, and sense a small enough volume to represent the important scales of the flow. We have constructed an acoustic travel time sensor in a configuration that will allow vector components of the flow to be measured with sufficient accuracy to compute Reynolds stress at a point 50 cm above the bottom. This sensor responds linearly to horizontal and vertical flows in flume tests. When the flow is neither horizontal nor vertical, the wake from one acoustic transducer may interfere with the measurement along one sensing path but there is sufficient redundancy in the determination to reject this path and still resolve the vector velocity. An instrument· using four of these sensors is being designed to measure Reynolds stress in the lower six meters of the ocean.
    Description: Prepared for the Office of Naval Research under Contract N00014-74-C-0262; NR 083-004.
    Keywords: Boundary layer ; Underwater acoustics ; Benthos
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  • 25
    Publication Date: 2022-05-26
    Description: Formulas for curve fitting and ray computation using compound models made up of several different layers are presented. Examples of computation by pocket programmable calculator on two Sargasso Sea profiles, one from the center of a cold ring eddy are given. Necessary tables of the incomplete beta-function and calculator programs are included in a supplement.
    Description: Prepared for the Office of Naval Research under Contract N00014-77-C-0196.
    Keywords: Underwater acoustics ; Ocean sounds
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  • 26
    Publication Date: 2022-05-26
    Description: The Mid-Ocean Dynamics Experiment (MODE) under the Office of the International Decade of Oceanography, National Science Foundation, included plans for the deployment of long-range SOFAR floats in a two degree square area approximately 400 miles Southwest of Bermuda. The floats are located by AFETR, MILS system hydrophones at Bermuda, Eleuthera and Puerto Rico. An additional station at Grand Turk Island, British West Indies, was requested to provide an expanded and more reliable location. In addition a spare installation was to be provided which could be installed within relatively short notice at Eleuthera or Puerto Rico if required. The design, logistical considerations and installation of the Grand Turk Island station are documented in this report.
    Description: Prepared for the National Science Foundation under Grant GX-32571.
    Keywords: Mid-Ocean Dynamics Experiment (MODE) ; Oceanographic buoys ; Underwater acoustics ; Oceanographic research stations
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  • 27
    Publication Date: 2022-05-25
    Description: This report describes the design and capabilities of a new ocean bottom hydrophone instrument. The instrument is microprocessor controlled and records digitally on a commercially available cartridge tape recorder with a formatted capacity of 16.7 megabytes. It can operate at sampling intervals between 80 and 8500 Hz and has a dynamic range of 120dB. Both the hardware and software are designed to provide the maximum flexibility in operation allowing either preprogrammed or event detect operation for either short deployment high sampling rate experiments or extended deployment low data rate applications. The microprocessor and recording electronics are capable of handling four data channels and thus the existing recording package is suitable for the ocean bottom seismometer application (or similar} with little or no modification.
    Description: Prepared for the Office of Naval Research under Contract N00014-82-C-0019; NR 083-004.
    Keywords: Hydrophone ; Underwater acoustics
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  • 28
    Publication Date: 2022-05-25
    Description: A study was carried out to quantify the level of numerical noise in numerical scattering chamber (NSC) calculations and to compare these noise levels with signal levels of body waves, interface waves and ambient noise. The amplitudes of signal and noise in snapshots from the numerical scattering chamber were quantified at 50 and 65 periods for a few reference models. Models with homogeneous subseafloor structure were studied to determine the level of numerical noise; models with a wavenumber-correlation length product of one were examined to determine signal levels. Models were run with both Higdon and telegraph equation absorbing boundaries since the numerical noise within the grid depends on the boundary formulation. Amplitudes were measured along data traces obtained at a grid depth of 3.33 λw and at the seafloor. Forward traveling head waves had typical amplitudes of ±125 but may reached ±250 near the direct wave. Diffraction amplitudes were observed up to ±300. Stoneley wave amplitudes ranged from ±800 up to ±20,000. Numerical noise levels were less than ±25 in most areas of the water and less than ±350 along most of the seafloor. Regardless of the absorbing boundary type, however, there was a region of noise extending up to 15 λw behind the first seafloor reflection at 3.33 λw in which noise levels range from ±100 up to ±600. In this region it is difficult to resolve signal from systematic numerical noise.
    Description: This work was carried out under ONR Grant #N00014-90-J-1493
    Keywords: Underwater acoustics ; Scattering
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  • 29
    Publication Date: 2022-05-25
    Description: This report describes the development of a facility for recording time-varying computer graphics on video tape. The primary purpose of the facility is to produce animation sequences of ocean and seafloor acoustic wave fields from output of the synthetic seismogram numerical model FINDIF, and to record them on convenient portable VHS video tapes. The facility utilizes a suite of computer programs called AFRAME, and an Abekas model A60 digital video disk which is connected to the modeling computer and to broadcast quality video recording equipment.
    Description: This work was carried out under ONR Grant #N00014-90-J-1493
    Keywords: Seismograms ; Acoustic models ; Underwater acoustics
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  • 30
    Publication Date: 2022-05-26
    Description: A sequence of nine nighttime, broadband volume scattering strength measurements obtained in 1973 over a period of approximately one hour was used to study the short-term variability of scattering strength in 100 Hz bands over frequencies ranging from 100 Hz to 24 kHz and depths ranging from 400 meters to 1000 meters. The variability was found to be independent of depth and was least in the frequency range three kHz to eight kHz where the standard deviation was approximately four dB less than the mean level, Outside this frequency range the standard deviation was somewhat greater than the mean level.
    Description: This work was funded by the Naval Underwater Systems Center, Commercial Acquisition Dept., Building 11, Code 09, Newport, Rhode Island 02841-5047 under contract number N00140-85-C-JA45.
    Keywords: Underwater acoustics ; Sound-waves
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  • 31
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: This is the final report of Contract N00014-84-C-0185 between the Woods Hole Oceanographic Institution and the Office of Naval Research for the contract period 1 January, 1984, to 28 February, 1985. This contract supported an experiment that was conducted in the Norwegian Sea during May and June of 1984 to assess the possibilities of using ocean acoustic tomography as a measuring tool in the Arctic. The object of the experiment was to identify and determine the temporal stability (coherence), and resolvability, of Arctic acoustic paths. Identification refers to the ability to match a pulse arrival with a particular ray path, primarily through computer modelling. Resolvable rays are those that arrive sufficiently far apart in time so as to be distinct and separable. In order to use tomography, rays must be identified, resolved and stable. Unlike the deep temperate ocean, where there are many wholly refracted paths, the upward refracting Arctic sound speed profile causes ray paths to reflect off the ice-covered surface of the permanent pack and the mixed ice-covered and ice-free surface of the marginal ice zones. The reflection process is time-varying and hence leads to resolvability, identification and stability questions that do not arise in the case of entirely refracted paths. A 224 Hz acoustic source was moored in an ice-free region. It transmitted phase coded, frequency stable signals to receivers fixed on the bottom and receivers drifting with the icepack at ranges of approximately 150 km. The received signals are to be analyzed with respect to identification, resolvability and stability issues. This contract covered the costs associated with installation and retrieval of the source and preliminary data reduction from the drifting and fixed hydrophones. Detailed data analysis costs are to be covered elsewhere. Nevertheless, preliminary analysis indicates that the received signals, particularly those from paths that interact with the ice-free surface, appear to have sufficient stability for tomographic purposes.
    Description: Funding was provided by the Office of Naval Research under Contract N00014-84-C-0185.
    Keywords: Underwater acoustics ; Tomography ; Sound ; Hearing
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  • 32
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: This is the final report of Contract N00014-77-C-0196 between the Woods Hole Oceanographic Institution and the Office of Naval Research for the contract period l January 1977 to 28 February 1983. This contract supported a broad program of research and development in underwater acoustics related to present and future Navy systems and requirements. The bulk of this contract research was conducted from 1977 to 1981, during which time the categories outlined below were all areas of active research. (Between 1981 and 1983 the contract remained in effect, although only in the area of bottom acoustics and at a reduced level.) The primary contract products are the published technical reports and papers listed below. These reports give detailed descriptions of the research work and the specialized techniques, methods, and instrumentation developed to support this research program. The final report contains a brief review of the program highlights and a bibliography of associated reports.
    Description: Funding was provided by the Office of Naval Research under Contract N00014-77-C-0196.
    Keywords: Underwater acoustics ; Signal processing
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  • 33
    Publication Date: 2022-05-26
    Description: The Ocean Bottom Seismometer Augmentation in the North Pacific Experiment (OBSANP, June-July, 2013, R/V Melville) addresses the coherence and depth dependence of deep-water ambient noise and signals. During the 2004 NPAL Experiment in the North Pacific Ocean, in addition to predicted ocean acoustic arrivals and deep shadow zone arrivals, we observed "deep seafloor arrivals" (DSFA) that were dominant on the seafloor Ocean Bottom Seismometer (OBS) (at about 5000m depth) but were absent or very weak on the Distributed Vertical Line Array (DVLA) (above 4250m depth). At least a subset of these arrivals correspond to bottomdiffracted surface-reflected (BDSR) paths from an out-of-plane seamount. BDSR arrivals are present throughout the water column, but at depths above the conjugate depth are obscured by ambient noise and PE predicted arrivals. On the 2004 NPAL/LOAPEX experiment BDSR paths yielded the largest amplitude seafloor arrivals for ranges from 500 to 3200km. The OBSANP experiment tests the hypothesis that BDSR paths contribute to the arrival structure on the deep seafloor even at short ranges (from near zero to 4-1/2CZ). The OBSANP cruise had three major research goals: a) identification and analysis of DSFA and BDSR arrivals occurring at short (1/2CZ) ranges in the 50 to 400Hz band, b) analysis of deep sea ambient noise in the band 0.03 to 80Hz, and c) analysis of the frequency dependence of BR and SRBR paths. On OBSANP we deployed a 32 element VLA from 12 to 1000m above the seafloor, eight short-period OBSs and four long-period OBSs and carried out a 15day transmission program using a J15-3 acoustic source.
    Description: Funding was provided by the Office of Naval Research under contract #'s N00014-10-1-0987 and N00014-10-1-0510
    Keywords: Melville (Ship) Cruise MV1308 ; Underwater acoustics ; Oceanographic instruments
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    Type: Technical Report
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  • 34
    Publication Date: 2022-05-26
    Description: The SMILE (Shelf Mixed Layer Experiment) field program took place during the winter of 1988-1989. The SMILE program itself was large and involved many investigators and instruments. This report documents the use of the Surface Acoustic Shear Sensor (SASS) as part of the suite of measurements taken during SMILE. The SMILE mooring array was deployed from early November 1988 until June, 1989. SASS, being a newly developed instrument, was deployed for two shorter periods; a test deployment between November 26 and December 8, 1988, and a longer second deployment, February 23 through March 14, 1989. SASS is based on BASS (Benthic Acoustic Stress Sensor) components (Williams et al., 1987), mounted on a structure that allowed continuous sampling of velocity, temperature and conductivity in the top five meters of the ocean. BASS was modified for this surface application to acquire data from a gyro, and conductivity sensors. The attitude data from the gyro allows the velocities of the current meter to be referenced to an inertial frame of reference. The other data obtained from SASS will be used to calculate shear current gradients, and other descriptors of turbulence and mixing.
    Description: Prepared for the National Science Foundation under Contract Number OCE-8716937.
    Keywords: Shelf Mixed Layer Experiment (SMILE) ; Deep-sea moorings ; Underwater acoustics ; Wecoma (Ship) Cruise
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  • 35
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: This interim report covers the progress of the acoustic telemetry project during the period 12/1/88 to 5/15/89. In general, the work followed the format specified in WHOI proposal No. 5674.1. The major exception was the deletion of the transmitter array development task and a corresponding funding decrease from $242,242 to $170,000. In addition, the period for the funding was extended to June 30, partly due to a two month delay in project startup. The telemetry project was centered around the construction, programming and testing of a digital receiver prototype capable of supporting future signal processing algorithms in real-time over ocean acoustic channels. The baseline receiver consists of a two-channel analog quadrature demodulator, and interface to a multiprocessor receiver for digital signal processing. The software developed includes routines for command and control of the analog demodulator, data handling and formatting, and minimal software to digitally implement an incoherent MFSK demodulator, synchronizer and data decoder. Data storage and display programs were also completed to facilitate the performance analysis of the unit during testing. The system was tested in Woods Hole harbor at data rates up to 4800 bits/sec. The acoustic channel was time-dispersive Rayleigh fading, and performance close to theoretical expectations was achieved. We are confident that the system error behavior is arising from channel-caused effects and known deficiencies in system performance, such as excessive synchronizer steady-state jitter.
    Description: Funding was provided by the Office of Naval Research under contract Number N00014-86-K-0751, and by the Charles Stark Draper Laboratory Inc.
    Keywords: Data transmission systems ; Digital communications ; Underwater acoustics
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  • 36
    Publication Date: 2022-05-26
    Description: At the request of ONR Code 11250A, the Woods Hole Oceanographic Institution (Dr. James F. Lynch) convened a workshop to bring together a group of acoustic and ocean modelers to review and discuss 1. the state of development and the need for three-dimensional numerical acoustic research propagation and scattering models; 2. the interfacing of acoustic models with available oceanographic data and ocean model outputs. The workshop was hosted by the Institute for Naval Oceanography (Dr. Ching-Sang Chiu) at Long Beach, MS on July 7-8, 1988. This report summarizes the research presentations and the recommendations made by the group. The workshop was an initial attempt to promote the interaction between the ocean and acoustic modeling communities. This interaction between the communities is essential to the development of truly interactive basic research acoustic and ocean models. We anticipate more workshops of such nature to be held in the future. The findings and recommendations generated by these workshops are expected to have a strong impact on the direction of future three-dimensional modeling research in both acoustics and oceanography .
    Description: Funding was provided by the Office of Naval Research under contract Number N00014-88-K-0363.
    Keywords: Underwater acoustics
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  • 37
    Publication Date: 2022-05-26
    Description: This report gives an overview of the analysis that was done on Deep Seafloor Arrivals since they were initially presented in Stephen et al (2009). All of the NPAL04/LOAPEX (North Pacific Acoustic Laboratory, 2004/ Long Range Ocean Acoustic Propagation Experiment) data on three ocean bottom seismometers (OBSs) at ~5,000m depth and the deepest element of the deep vertical line array (DVLA) at 4250m depth has been analyzed. A distinctive pattern of late arrivals was observed on the three OBSs for transmissions from T500 to T2300. The delays of these arrivals with respect to the parabolic equation predicted (PEP) path were the same for all ranges from 500 to 2300km, indicating that the delay was introduced near the receivers. At 500km range the same arrival was observed throughout the water column on the DVLA. We show that arrivals in this pattern converted from a PEP path to a bottom-diffracted surface reflected (BDSR) path at an off-geodesic seamount.
    Description: Funding was provided by the Office of Naval Research under Contract No. N00014-10-1-0510.
    Keywords: Underwater acoustics ; Ambient sounds
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  • 38
    Publication Date: 2022-05-25
    Description: The Ocean Bottom Seismometer Augmentation to the Philippine Sea Experiment (OBSAPS, April-May, 2011, R/V Revelle) addresses the coherence and depth dependence of deep-water ambient noise and signals. During the 2004 NPAL Experiment in the North Pacific Ocean, in addition to predicted ocean acoustic arrivals and deep shadow zone arrivals, we observed "deep seafloor arrivals" that were dominant on the seafloor Ocean Bottom Seismometer (OBS) (at about 5000m depth) but were absent or very weak on the Distributed Vertical Line Array (DVLA) (above 4250m depth). These "deep seafloor arrivals" (DSFA) are a new class of arrivals in ocean acoustics possibly associated with seafloor interface waves. The OBSAPS cruise had three major research goals: a) identification and analysis of DSFAs occurring at short (1/2CZ) ranges in the 50 to 400Hz band, b) analysis of deep sea ambient noise in the band 0.03 to 80Hz, and c) analysis of the frequency dependence of BR and SRBR paths as a function of frequency. On OBSAPS we deployed a fifteen element VLA from 12 to 852m above the seafloor, four short-period OBSs and two long-period OBSs and carried out an 11.5day transmission program using a J15-3 acoustic source.
    Description: Funding was provided by the Office of Naval Research under Contract Nos. N00014-10-1-0994 and N00014-10-1-0987.
    Keywords: Underwater acoustics ; Ambient sounds ; Roger Revelle (Ship) Cruise RR1106
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  • 39
    Publication Date: 2022-05-26
    Description: On the Ocean Bottom Seismometer Augmentation to the Philippine Sea Experiment (OBSAPS, April-May, 2011, R/V Revelle), a VLA and six OBSs were deployed to listen to an active acoustic source, a J15-3. This report describes the hardware and software used to control and record the acoustic transmissions from the source. Some significant features of the system are: 1) The system transmits general user-defined source functions, such as Msequences (.SIO files). 2) In addition to controlling the source waveform, the system also records six real-time channels in binary files with user-selectable lengths: the monitor hydrophone mounted near the source, the power amplifier voltage and current, the depth of the source, sonobuoy data (when deployed) and an IRIG-B time reference. Files are output in .AUV format with a precision GPS-based time stamp in the file name. 3) The transmission start time along with ADC and DAC sample rates are disciplined to GPS time. 4) A convenient, Labview based, user interface provides real-time source control and monitoring. 5) The software provides parsing and logging of gyro and GPS NMEA sentences. The system, which was based on an earlier system from Scripps MPL, worked well on OBSAPS and is available for future projects.
    Description: Funding was provided by the Office of Naval Research under Contract Nos. N00014-10-1-0994 and N00014-10-1-0987.
    Keywords: Underwater acoustics ; Ambient sounds
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  • 40
    Publication Date: 2022-05-26
    Description: This report describes a system for underwater acoustic navigation developed, and in use, at the Woods Hole Oceanographic Institution. It includes a brief discussion of the electronic components, operation, mathematical analysis, and available computer programs. There is a series of supplementary Technical Memoranda containing more information on various aspects of the system. We believe that this kind of documentation is more flexible and better meets the needs of potential users than including all technical details in one large volume. These are not final or definitive reports; acoustic navigation capabilities will continue to evolve at W.H.O.I. for some time. Acoustic navigation provides a method of tracking a ship, and an underwater vehicle or instrument package (‘fish’), in the deep ocean. Acoustic devices attached to the ship and fish measure the length of time it takes a sound pulse to travel to acoustic transponders moored on the ocean floor. If the transponder positions and the average speed of sound are known, the ship or fish position can be found.
    Description: Prepared for the Office of Naval Research under Contracts N00014-71-C0284; NR 293-008 N00014-70-C0205; NR 263-103 and the National Science Foundation/International Decade of Ocean Exploration Grant GX-36024 and the Applied Physics Laboratory of The Johns Hopkins University Contract 372111.
    Keywords: Alvin (Submarine) ; Underwater navigation ; Underwater acoustics
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  • 41
    Publication Date: 2022-05-26
    Description: 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.
    Description: Funding was provided by the Office of Naval Research under Contract No. N00014-04-10146
    Keywords: Underwater acoustics ; Oceanographic buoys ; Knorr (Ship : 1970-) Cruise KN183 ; Knorr (Ship : 1970-) Cruise KN184 ; Knorr (Ship : 1970-) Cruise KN185 ; Knorr (Ship : 1970-) Cruise KN186 ; Oceanus (Ship : 1975-) Cruise OC427 ; Oceanus (Ship : 1975-) Cruise OC428 ; Oceanus (Ship : 1975-) Cruise OC429 ; Endeavor (Ship: 1976-) Cruise EN424 ; Endeavor (Ship: 1976-) Cruise EN425 ; Hugh R. Sharp (Ship) Cruise 060622CM
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  • 42
    Publication Date: 2022-05-25
    Description: The results of an unclassified Workshop on Shallow Water Acoustics, sponsored by the Office of Naval Research Code 11250A, are presented. The workshop was held on April 24-26, 1991 at the Woods Hole Oceanographic Institution and included about forty-five scientists specializing in ocean acoustics, geology, geophysics, and physical oceanography. The goal of the workshop was to determine future directions for basic research in shallow water acoustics. This report summarizes the recommendations of the workshop and includes a synopsis of the deliberations of four working groups which focus on the following specific research issues: (1) the seabed, (2) the water column and surface/Arctic, (3) analytic and numerical modeling/ambient noise, and (4) laboratory and field experiments/signal processing.
    Description: Funding was provided by the Office of Naval Research through Contract No. NOOOl4-91-J-1776.
    Keywords: Shallow water acoustics ; Underwater acoustics ; Basic research recommendations
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  • 43
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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 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: Ocean instrumentation ; Underwater acoustics ; Oceanographic data collection
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    Type: Technical Report
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  • 44
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: The results of an unclassified workshop on Shallow Water Acoustics, jointly sponsored by ONR and DARPA, are presented. The workshop was held on October 1-3, 1996 at the Naval Research Laboratory, Stennis Space Center, and included 83 participants specializing in ocean acoustics, geology and geophysics, physical oceanography, and other disciplines relevant to shallow water research. The goal of the workshop was to help determine the current status of and future directions for shallow water acoustics research. The report summarizes the deliberations and recommendations of the workshop, and includes detailed report from the three working groups (bottom, water column, and modeling and signal processing) as well as from the workshop moderator (Dr. James Lynch, WHOI).
    Description: Funding was provided by the Office of Naval Research through Contract No. N00014-96-1-1031. Supported by ONR and DARPA.
    Keywords: Shallow water acoustics ; Underwater acoustics ; Basic research recommendations
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  • 45
    Publication Date: 2022-05-25
    Description: The primary objective of this publication is to share with a wider audience the valuable information and extensive dialogue that took place amongst over 140 individuals who attended the second in a series of planned workshops on the science and management of coastal landforms in Massachusetts. This workshop took place at the Woods Hole Oceanographic Institution on January 24, 2001. The individuals who attended this workshop are actively engaged in planning, managing, regulating, engineering, educating, and studying coastal landforms and their beneficial functions. This workshop titled, Can Humans & Coastal Landforms Co-exist?’, was a natural follow-up to a previous workshop, Coastal Landform Management in Massachusetts, held at WHOI October 9-10, 1997 (proceedings published as WHOI Technical Report #WHOI-98-16). The workshop had a very practical, applied focus, providing state-of-the-art scientific understanding of coastal landform function, case history management and regulation of human activities proposed on coastal landforms, a multi-faceted mock conservation commission hearing presented by practicing technical consultants and attorneys that involved all attendees acting as regulators in breakout sessions, and, at the conclusion of the workshop, an open discussion on all issues related to the science and management of coastal landforms, including future research needs.
    Description: Funding for these proceedings was provided by WHOI Sea Grant and the NOAA National Sea Grant College Program Office, Department of Commerce, under NOAA Grant No. M10-2, Woods Hole Oceanographic Institution Sea Grant Project No. NA86R60075.
    Keywords: Coastal ; Landforms ; Humans
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  • 46
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    Woods Hole Oceanographic Institution
    Publication Date: 2022-05-26
    Description: This report describes a non-rigid, floating, four-hydrophone array that can give accurate three-dimensional locations for certain underwater sound sources, particularly for those that are close. For more distant sounds, the array can indicate good directions (bearings) but range is liable to be uncertain. A system for concurrent calibration permits periodic reassessment of hydrophone positions. Appendix: Programming and mathematics for computer analysis of the array data are by Donna Ekstrand and Mary Hunt.
    Description: Supported by the Office of Naval Research under Contract N00014-66-C0241; NR 083-004.
    Keywords: Underwater acoustics ; Hydrophone ; Three-dimensional locations ; Array ; Ambient noise ; Instruments
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: 3659902 bytes
    Format: application/pdf
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