The simultaneous measurement of infrasonic acoustic particle velocity and acoustic pressure in the ocean by freely drifting Swallow floats

D’Spain, Gerald L.; Hodgkiss, William S.; Edmonds, G. L.

doi:10.1109/48.84136

Cited by 92 publications

(53 citation statements)

References 15 publications

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“…Excellent agreement between the laboratory-measured and theoretically-predicted amplitude and phase responses of both the geophone and hydrophone channel circuitry, and the sensors themselves, has been obtained [16].…”

Section: Appendix -Swallow Float Infrasonic Data Acquisition Systemmentioning

confidence: 83%

Trip Report - June 1989 Swallow Float Deployment with RUM

D’Spain¹,

Hodgkiss²,

Edmonds³

1990

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Public reporting burden for this collection of Informatlon Is estimated to aVerae 1 hour per response. Including the time for reviewing instructlOn seaching existing data soulces, fihe nd maintaining the data needed. and compteting and rvwing the collection of Information. Approved for public release; distribution is unlimited. Abstract (Maximum 200 words).The deployment of the three Marine Physical Laboratory's Swallow floats using the Remote Underwater Manipulator (RUM) was conducted in June, 1989 in the deep northeast Pacific Ocean at 32.4 N, 120.7 W. Representative data collected by the two properly-functioning Swallow floats, one with an external, triaxial geophone package resting on the ocean bottom and the other equippd with an infrasonic hydrophone and bottom-tethered by a 0.5-meter line, are presented in this report.14. Subject Terms. Number of Pages.Swallow float, ambient noise, particle velocity, data acquisition system 80 16. Price Code. 17 ABSTRACTThe deployment of three of the Marine Physical Laboratory's Swallow floats using the Remote Underwater Manipulator (RUM) was conducted in June, 1989 in the deep northeast Pacific Ocean at 32.40 N, 120.70 W. Representative data collected by the two properly-functioning Swallow floats, one with an external, triaxial geophone package resting on the ocean bottom and the other equipped with an infrasonic hydrophone and bottom-tethered by a 0.5-meter line, are presented in this report

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Section: Appendix -Swallow Float Infrasonic Data Acquisition Systemmentioning

confidence: 83%

Trip Report - June 1989 Swallow Float Deployment with RUM

D’Spain¹,

Hodgkiss²,

Edmonds³

1990

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“…However, there is a more useful form derived by Nyquist 5 . The spectral density of the fluctuations can be related directly to the damping.…”

Section: Thermal Radiationmentioning

confidence: 99%

“…The impact of processing nonuniformity is minimized by the common-centroid design. In contrast, microsensor mechanical structures are not ordinarily [3][4][5][6] suited to common-centroid design and are sensitive to process irregularities and thermal gradients.…”

Section: -4mentioning

confidence: 99%

Micromachined Directional Hydrophones

Gabrielson¹

2000

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Regional actions in littoral waters will likely take the form of rapidly developing conflicts involving multiple surface-ship, mine, and submarine threats. The mission effectiveness of various Navy assets would be greatly enhanced with a deployable multi-threat sensor system for underwater warfare. One critical component of such a system is a miniature, directional hydrophone (or acoustic velocity sensor). While useful in platform systems as well, miniaturization of velocity hydrophones has the greatest payback in deployable systems -either sonobuoy systems or longer-life deployable systems. Current directional sonobuoys employ accelerometer-based velocity sensors using piezoelectric materials for transduction. However, miniaturization favors other forms of transduction. One form that is particularly suited to microfabrication is the differential-capacitance accelerometer. The differential-capacitance configuration is capable of good long-term stability and exceptional low-frequency noise performance. The effective sensor impedance is determined not by the signal frequency but by the AC drive frequency. The differential-capacitance accelerometer does not have an inherent roll-off in response at low frequency so these devices can be used in self-orienting three-axis sensors for deployable systems. This report documents an investigation into the fundamental limits associated with miniaturization of velocity hydrophones and the development of the differential-capacitive sensor as a directional hydrophone element.Dfctnoution Unlimited ymn r-T)7\T ,vr-Y HX^'7'vI^B 4 Public reporting burden for this collection of Information Is estimated to average 1 hour per response, including the time for reviewing Instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, REPORT DOCUMENTATION PAGE ABSTRACT (Maximum 200 words)Regional actions in littoral waters will likely take the form of rapidly developing conflicts involving multiple surface-ship, mine, and submarine threats. The mission effectiveness of various Navy assets would be greatly enhanced with a deployable multi-threat sensor system for underwater warfare. One critical component of such a system is a miniature, directional hydrophone (or acoustic velocity sensor). While useful in platform systems as well, miniaturization of velocity hydrophones has the greatest payback in deployable systems -either sonobuoy systems or longer-life deployable systems. Current directional sonobuoys employ accelerometer-based velocity sensors using piezoelectric materials for transduction. However, miniaturization favors other forms of transduction. One form that is particularly suited to microfabrication is the differential-capacitance accelerometer. The differential-capacitance configuration is capable of good long-term stability and exceptio...

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“…One significant practical difficulty with seismometers is the coupling between the solid earth and the sensors as well as the device resonance. 5 Using seismometers in water posses even more difficult coupling problems but new developments in miniature accelerometers have solved the largest part of this problem by designing a small, rigid, neutrally buoyant sensor. Moving an accelerometer-based sensor through the water would require a more practical suspension solution while minimizing the flow noise.…”

mentioning

confidence: 99%

“…Vector sensors have been used to study the directional nature of noise in the ocean as well as to track whales. 4,5 Using a vector sensor with a controlled pulse source, one can determine both range and bearing for the sound source as well as scattering and reflection points. In the case of nonoverlapping reflections, the vector time series from a single source pulse recorded at a single position can provide a threedimensional acoustic picture of the local environment.…”

mentioning

confidence: 99%

Imaging marine geophysical environments with vector acoustics

Lindwall¹,

Wilson²

2006

The Journal of the Acoustical Society of America

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Using vector acoustic sensors for marine geoacoustic surveys instead of the usual scalar hydrophones enables one to acquire three-dimensional (3D) survey data with instrumentation and logistics similar to current 2D surveys. Vector acoustic sensors measure the sound wave direction directly without the cumbersome arrays that hydrophones require. This concept was tested by a scaled experiment in an acoustic water tank that had a well-controlled environment with a few targets. Using vector acoustic data from a single line of sources, the three-dimensional tank environment was imaged by directly locating the source and all reflectors.

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The simultaneous measurement of infrasonic acoustic particle velocity and acoustic pressure in the ocean by freely drifting Swallow floats

Cited by 92 publications

References 15 publications

Trip Report - June 1989 Swallow Float Deployment with RUM

Trip Report - June 1989 Swallow Float Deployment with RUM

Micromachined Directional Hydrophones

Imaging marine geophysical environments with vector acoustics

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