| A Broadband Towed Line Array with Spatial Discrimination Capabilities |
11 FEB 2004 |
16 pages |
| Authors:
Kim C. Benjamin; Kenneth M. Walsh; DEPARTMENT OF THE NAVY WASHINGTON DC
|
 | A modular sub-array assembly of a composite towed array includes a multi-chamber support structure with plural discrete chambers, an acoustically absorptive hub formed at a central axis of the multi-chamber support structure, and a sensor element in each of the chambers of the multi-chamber support structure. The multi-chamber support structure is an integrally formed viscoelastic cylindrical housing with an array of radially oriented chambers. Each sensor element is secured within ... |
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| Elastomeric Ejection System with Acoustically Improved Check Valve |
11 FEB 2004 |
17 pages |
| Authors:
William P. Barker; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A system for launching bodies from a submarine includes a pump for transferring seawater to an elastomeric ejection tank, and a check valve that permits transfer of the seawater to the tank, and closes upon filling of the tank. The valve includes a head and a seat, a stem having fixed thereon the head and a disk having a circular protrusion extending toward the seat, a cup mounted around the ... |
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| Buried Target Detection Using Time-Reversed Acoustics |
06 FEB 2004 |
|
| Authors:
David Pierson; T. F. Clark; NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MARINE EARTH AND ATMOSPHERIC SCIENCES
|
 | In the spring of 2000, a proposal was submitted to Mr. Ken Dial at the Office of Naval Research (ONR) to study a novel approach of time-reversed acoustics to detect targets buried in a littoral environment. The proposal was written by Dr. Thomas Drake, currently at ONR, and David Pierson, currently at John Hopkins University Applied Physics Laboratory (APL), under the advice of Dr. Tony Clark, currently at North Carolina ... |
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| Performance Analysis of Subaperture Processing Using a Large Aperture Planar Towed Array |
FEB 2004 |
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| Authors:
Jennifer A. Watson; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF APPLIED OCEAN PHYSICS AND ENGINEERING
|
| In recent years the focus of passive detection and localization of submarines has moved from the deep ocean into the littoral regions. The problem of passive detection in these regions is complicated by strong multipath propagation with high transmission loss. Large aperture planar arrays have the potential to improve detection performance due to their high resolution and high gain, but are susceptible to two main performance degradation mechanisms: limited spatial ... |
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| Environmental Mitigation Ranges around Australia |
FEB 2004 |
|
| Authors:
Paul Clarke; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION EDINBURGH (AUSTRALIA) MARITIME OPERATIONS DIV
|
| URS Australia is currently writing "Environmental Management Plan for Australian Maritime Exercise Areas" for the ADF. To help URS, the MOD within DSTO has modeled the expected received sound pressure levels for a number of different environments and sonar frequencies around Australia. The maximum ranges the sound pressure levels dropped below 182 and 160 dB were then calculated for a number of different sonars operating at levels indicative of or ... |
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| Biomimetic Dolphin Sonar Source |
20 JAN 2004 |
5 pages |
| Authors:
Ted W. Cranford; Wesley R. Elsberry; QUANTITATIVE MORPHOLOGY CONSULTING SAN DIEGO CA
|
| Dolphin click generators were studied via anatomy, tissue properties, physiology, and acoustic analyses. Our objective was to design, produce, and test computational models and physical devices that mimic dolphin sonar signal generation. Our multi-mass computational model of dolphin click production was based the Steinecke-Herzel model of the human larynx. We developed and implemented an acoustic model that translates the motions from our multi-mass model into acoustic signals. We also mastered ... |
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| A Sonar Dome and a Mounting Bracket for Removably Connecting an Acoustic Sensor Element to a Sonar Dome |
05 JAN 2004 |
16 pages |
| Authors:
Thomas S. Ramotowski; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A mounting bracket for removably connecting an acoustic sensor element to an inside wall of a sonar dome of a marine vessel includes a first protrusion bonded at a first end thereof to the inside wall of the sonar dome, extending inwardly therefrom, and provided with a first widthwise extending slot proximate, but spaced from, the inside wall, and a second protrusion bonded at a first end to the sonar ... |
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| Measuring the Behavior and Response to Sound of Beaked Whales Using Recording Tags |
01-Jan-2004 |
|
| Authors:
Mark Johnson; Peter Tyack; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| The goals of this project are to understand the reasons for, and to help reduce, the strandings of two little-known species of beaked whales related to mid-frequency navy sonars. Although they are widely distributed, these cryptic species have proven extremely difficult to study and, until recently, almost nothing was known about their subsurface behavior or vocalizations. The current project combines an advanced acoustic and orientation recording tag with methods of ... |
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| NPS ARIES Forward Look Sonar Integration |
01-Jan-2004 |
|
| Authors:
A J Healey; D P Horner; NAVAL POSTGRADUATE SCHOOL MONTEREY CA CENTER FOR AUTONOMOUS UNDERWATER VEHICLE RESEARCH
|
| This work integrated an experimental Blazed Array Forward Looking Sonar (FLS) developed by the University of Washington, Applied Physics Laboratories into the ARIES autonomous underwater vehicle (AUV). Experiments were conducted and data were gathered using this sonar in a variety of environments. The images generated were analyzed to provide information for use in the further development of forward look obstacle detection and avoidance technologies. The year-end goal of the project ... |
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| Development of Computational Simulation Tools to Model Weapon Propulsors |
2004 |
18 pages |
| Authors:
S. J. Couillard; J. M. Rice; MASSACHUSETTS UNIV NORTH DARTMOUTH
|
| The development of computational simulation tools, i.e. finite element (FE) models, to model weapon propulsors evolves from the need to determine the positive or negative implications for future applications and/or design modifications. The propulsor in this case is an electric motor used in such applications as propelling defense mechanisms like torpedoes and acquiring underwater data. The ability to predict, with a computer model, the vibrational and acoustical signatures allows the ... |
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| Beamforming Arrays with Faulty Sensors in Dynamic Environments |
2004 |
20 pages |
| Authors:
Jeffrey Krolik; Oguz R. Kazanci; Dinesh Ramakrishnan; DUKE UNIV DURHAM NC DEPT OF ELECTRICALAND COMPUTER ENGINEERING
|
| This paper addresses the problem of beamforming a uniform linear array when some of the receive elements are not operational. Bad sensors are often handled by either zeroing or interpolating the faulty elements prior to conventional beamforming. While zeroing faulty elements prior to conventional beamforming is the simplest approach, it often results in undesirably high beamformer sidelobes. Alternatively, minimum mean-square error (MMSE) interpolation of the missing data is not explicitly ... |
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| Underwater Multimode Directional Transducer Evaluation |
DEC 2003 |
|
| Authors:
Guilherme d. Sineiro; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| The work described in the present thesis is intended to establish a procedure for analyzing directional transducers for future underwater wireless networks, as well as to carry out the performance evaluation of a multimode transducer prototype with respect to its main operational requirements. Measurement techniques were designed for application in the presence of physical limitations of the available facilities and the prototype development stage of the test unit. |
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| A Real-Time Audio Tele-Presence Device for Remote Acoustic Monitoring |
DEC 2003 |
46 pages |
| Authors:
Michael A. Vaudrey; Sujayeendar Sachindar; ADAPTIVE TECHNOLOGIES INC BLACKSBURG VA
|
| This Small Business Innovation Research program sponsored by the U.S. Army Research Laboratory (ARL) addressed the issue of remote monitoring of acoustic environments with the hearing acuity a soldier is accustomed to, without placing the soldier in a potentially hostile acoustic environment. To achieve this goal, Adaptive Technologies, Inc. (ATI) employed a product-oriented design strategy to develop a wired proof-of-concept prototype using commercial- on-the- shelf components. At the end of ... |
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| Estimation of Low Frequency Scattering from Fish Schools on the Continental Shelf off New Jersey |
10 NOV 2003 |
13 pages |
| Authors:
Redwood W. Nero; Richard H. Love; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS ACOUSTIC SIMULATION SECTION
|
| The GeoClutter 2001 (GCOi) experiment conducted on the continental shelf of New Jersey in April and May 2001 focused on physical mechanisms causing geologically produced acoustic clutter and false targets around 400 Hz. During OCOl, a large, strong unidentified target was detected. In May 2001, backscatter measurements from the ocean volume were made in the same area at 2 to 10kHz and at 38kHz to examine scattering from fish during ... |
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| A Nonlinear Programming Algorithm for Optimizing Conventional Beamformer Shading Weights |
10 NOV 2003 |
30 pages |
| Authors:
Thomas A. Wettergren; John P. Casey; Charles M. Traweek; NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI
|
| A numerical method to determine the optimal shading weights for a conventional delay-and-sum beamformer has been developed. The method employs a maximization of the deflection coefficient under the constraint of maintaining signal gain. This provides an optimal array shading scheme based on available noise data. The algorithm has been implemented using off-the-shelf numerical methods that are applicable only for small arrays. For large arrays, a special- purpose optimization algorithm has ... |
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| Preliminary Observations Regarding LDV Scans of Panels Excited by Broadband Actuators at the US Capitol |
07 NOV 2003 |
54 pages |
| Authors:
J. A. Bucaro; J. Vignola; B. H. Houston; A. J. Romano; NAVAL RESEARCH LAB WASHINGTON DC
|
| Experiments were conducted on frescos and wall paintings at the U.S. Capitol Building in order to determine the effectiveness of an electro-magnetic shaker-based approach of evaluating the condition of the substructure. A scanning laser Doppler vibrometer (LDV) was used to measure the vibratory response of the work of art subjected to the shaker excitation. This report contains a representative sample of the data obtained on two panels as well as ... |
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| San Clemente Island Undersea Range Acoustic Experiment, July 2002 |
04 NOV 2003 |
79 pages |
| Authors:
Christopher W. Miller; Anurag Kumar; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OCEANOGRAPHY
|
| An at-sea data collection effort was conducted July 24-28, 2002 in support of the Naval Postgraduate School's Tactical Oceanography Course (OC- 4270) off the San Clemente Island Undersea Range (SCIUR). The experiment configuration was designed to provide acoustic propagation measurements for transmission loss, detection range limitation, and acoustic variability in the 1-8 kHz frequency band. This report is provided to document contacts, experiment configuration, execution and collected data sets. |
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| Setup and Troubleshooting Procedures for the Klein 5500 Sidescan Sonar |
NOV 2003 |
|
| Authors:
Colin Andrew; Amy Young; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION SALISBURY (AUSTRALIA) SYSTEMS SCIENCES LAB
|
| This document outlines in detail all facets associated with the set up and usage of the Klein 5500 sidescan sonar. In particular this document outlines: (1) the different types of hardware that are required, how they need to be set up and networked, (2) how to set up and use the acquisition software packages Isis and SonarPro, and (3) how to detect, analyse and troubleshoot incorrect set up and malfunctions ... |
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| Electrostrictive Polymers for Advanced Sonar Transducers (EPAT). Volume 2 |
10 OCT 2003 |
|
| Authors:
Q. M. Zhang; T. Zhu; V. Bharti; T. Mai; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
|
| This report contains several symposia papers and journal articles on the following topics: Characterization of Electrostrictive P(VDF-TrFE) copolymers Film for High Frequency and High Load Applications; New Electrostrictive PVDF Copolymers for Large-Strain Actuator Application; Synthesis and Electric Property of VDF/TrFE/HFP Terpolymers; Giant Electrostrictive Response in Poly(Vinylidene-Fluoride-Hexafluoropropylene) Copolymer; Electro-Mechanical Properties of Electron Irradiated P(VDF-TrFE) copolymers under Different Mechanical Stresses; Electroactive Polymer Actuators and Devices - P(VDF-TrFE)-based Electrostrictive Co/Ter-polymers and its Device ... |
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| Electrostrictive Polymers for Advanced Sonar Transducers (EPAT). Volume 1 |
10 OCT 2003 |
193 pages |
| Authors:
Qiming Zhang; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
|
| The objective of this DARPA program is to develop high performance electroactive polymers and demonstrate the new polymers for underwater high- power sonar transducers. Through the support of this DARPA program, the electromechanical responses of the high energy electron irradiated copolymer have been improved significantly and PVDF based electrostrictive terpolymers with electromechanical performance better than the irradiated copolymers have been developed. The scale-up of the terpolymer production is current underway ... |
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| Gaseous Cavity for Forward-Looking Sonar Quieting |
06 OCT 2003 |
13 pages |
| Authors:
Robert Kuklinski; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| This patent application discloses a sonar quieting system for a forward-looking sonar array. The sonar quieting system includes a cavitator for forming an envelope; a strut for supporting the cavitator to a marine platform, such as a ship; a forward-looking sonar array mounted to a forward face of the cavitator; and a ventilation system for pumping a gas, such as air, into the envelope to create a gas cavity that ... |
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| A Laser Vorticity Probe for the Characterization and Control of Turbulent Boundary Layers |
01 OCT 2003 |
61 pages |
| Authors:
M. V. Otugen; POLYTECHNIC UNIV BROOKLYN NY DEPT OF MECHANICAL AEROSPACE AND MANUFACTURING ENGINEERING
|
| A laser-based probe for the direct, non-intrusive measurement of temporally- and spatially-resolved velocity gradient and vorticity is developed and demonstrated. The optical probes developed were used in turbulent two-stream mixing layers as well as laminar and turbulent boundary layers for the measurement of several velocity gradients and spanwise vorticity. The measurement technique is based on the collection and direct heterodyning of coherent light scattered from particles in two adjacent locations ... |
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| Interactive Multisensor Analysis Training |
OCT 2003 |
15 pages |
| Authors:
Wallace H. Wulfeck Ii; Sandra K. Wetzel-Smith; Janet L. Dickieson; SPACE AND NAVAL WARFARE SYSTEMS CENTER SAN DIEGO CA
|
| The Interactive Multisensor Analysis Training (IMAT) project is aimed at improving the preparation of operational users of undersea-warfare sensor systems. The effort has focused on training at all levels from initial individual training ashore through team, platform, and collective training at- sea, at all skill levels from apprentice sensor operators to senior tactical commanders. Operators and tacticians at all levels need a deep and scientifically accurate, but not necessarily formal, ... |
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| Acoustic Proximity Ranging in the Presence of Secondary Echoes |
OCT 2003 |
14 pages |
| Authors:
Xi Li; Renbiao Wu; Srihari Rasmi; Jian Li; III Cattafesta Louis N.; Mark Sheplak; FLORIDA UNIV GAINESVILLE DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| Proximity ranging is very important in many applications. Ultrasonic sensors have proven to be very cost effective tools for this purpose. Most of the currently available time-of-flight based acoustic proximity ranging systems use the conventional matched filter based time delay estimation approaches to measure short distances between proximity objects. However, in the presence of strong and closely spaced secondary echoes, the aforementioned matched filter based algorithms tend to fail or ... |
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| Time-Exposure Acoustics for Imaging Underground Structures |
30 SEP 2003 |
20 pages |
| Authors:
Steve Norton; I. J. Won; Alan Witten; Alex Oren; Frank Funak; GEOPHEX LTD RALEIGH NC
|
| We have developed a new technique for imaging underground facilities based on the passive monitoring of acoustic emissions from both stationary and moving equipment within such facilities. It is well known that all mechanical devices, such as motors, gears, etc, emit acoustic signals. It is possible to identify an acoustic source based on its noise spectrum. Passive "listening" has been considered and employed in the past to detect underground structures ... |
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| Geometric Phased Beam Diver Held Sonar |
30 SEP 2003 |
90 pages |
| Authors:
Richard L. Tutwiler; Charles W. Allen; W. J. Hughes; PENNSYLVANIA STATE UNIV UNIVERSITY PARK APPLIED RESEARCH LAB
|
| A design for an underwater acoustic imaging system that would he portable enough to be operated by a diver was developed utilizing the geometric phased beam or 'doily' array concept. The 'doily' array design provides multiple beamsteering capability while drastically reducing the number of elements required. The system would operate in the I to 6MHz frequency range and only require 1808 channels. This report documents the state of the design ... |
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| Nondestructive Evaluation (NDE) Technology Initiative Program (NTIP). Delivery Order 0032: MAUS Implementation for Corrosion/Crack Detection in Wing Structure - Phase III |
30 SEP 2003 |
48 pages |
| Authors:
Donald D. Palmer Jr.; Nancy L. Wood; BOEING CO ST LOUIS MO PHANTOM WORKS
|
| This report summarizes the results of Phase III of the "MAUS implementation for Corrosion/Crack Detection in Wing Structure" program. During Phase III, all system optimization activities, including hardware and software enhancements to improve ultrasonic pulse-echo data collection and data interpretation, were completed. Also completed was the B-52 upper wing spanwise splice inspection process development and validation. The automated second layer ultrasonic inspection procedure developed was designed to rapidly detect fatigue ... |
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| Method and Apparatus for Active Sonar Detection Enhancement |
24 SEP 2003 |
22 pages |
| Authors:
Richard A. Katz; Albert H. Nuttall; NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI
|
| The present invention provides a method and apparatus for enhancing active sonar signal detection by estimating the channel/target response utilizing measured values of the excitation signals and received signals. A Wiener/Volterra series expansion for the excitation and received signals is used as a model, wherein a time invariant environment is assumed, thereby disregarding all random noise contributions. The Wiener/Volterra kernels are then determined in a nonlinear processor using a method ... |
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| Sensors for Micro Aerial Vehicles |
22 SEP 2003 |
26 pages |
| Authors:
Greg Mann; ARMY RESEARCH DEVELOPMENT AND ENGINEERING COMMAND REDSTONE ARSENAL AL
|
| Briefing charts from presentation of sensors and technologies developed for Micro Air Vehicles (MAV). |
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| Methane Hydrates DTAGS and Coring Cruise Off the Carolina Coast |
15 SEP 2003 |
31 pages |
| Authors:
Warren T. Wood; Kenneth Grabowski; Richard B. Coffin; Dennis A. Lindwall; Stephen Theophanis; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS MARINE GEOSCIENCES DIV
|
| From June 16 to July 19,2002, NRL conducted a research cruise aboard the RIV Cape Hatteras out of Beaufort NC over the Cape Fear diapir and slide, and over the Blake Ridge diapir. High-resolution multichannel seismic data was acquired in all areas, and over the Blake Ridge diapir, a long baseline acoustic navigation system was used to colocate the seismic data with piston and gravity cores. Estimated accuracy of the ... |
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| Additional Mine Classification Capabilities for the INSS |
10 SEP 2003 |
64 pages |
| Authors:
Min F. Chang; Charles M. Loeffler; TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
|
| As a diver scans shallow water or very shallow water (SW/VSW) area with an INSS high frequency sonar, many objects may be detected or imaged in the scene. The objective of this project is to develop algorithms that capture the broadband echo responses from these objects detected by the INSS and extract special echo features to assist in target discrimination from the background. The algorithms are based upon geometric acoustics, ... |
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| Blind Separation of Signal and Multipath Interference for Synthetic Aperture Sonar |
01-Sep-2003 |
9 pages |
| Authors:
Ivars P Kirsteins; NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI
|
| Multipath interference is a major source of noise for synthetic aperture sonar systems operating in shallow water. Motivated by this problem, we present an iterative algorithm for blindly separating the signal from the multipath interference that uses differences in the temporal coherence properties of the signal and multipaths caused by sea surface roughness to estimate the optimum filter weights. The filter weights are estimated by minimizing the circular variance of ... |
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| High Frequency Images of Proud and Buried 3D-Targets |
01-Sep-2003 |
8 pages |
| Authors:
Gary S Sammelmann; COASTAL SYSTEMS STATION PANAMA CITY FL
|
| PC SWAT (Personal Computer Shallow Water Acoustic Tool-set) is a sonar simulation package developed at Coastal Systems Station to predict acoustic sensor performance. This article focuses on the algorithms used by PC SWAT to generate synthetic images of proud, buried, and partially buried three-dimensional targets. High frequency scattering from the target is described by a combination of the Kirchhoff approximation and the Geometric Theory of Diffraction. Propagation of sound into ... |
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| NUWC XP-1 Polyurethane-Urea: A New, Acoustically Transparent Encapsulant for Underwater Transducers and Hydrophones |
01-Sep-2003 |
5 pages |
| Authors:
Thomas Ramotowski; Kirk Jenne; NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI
|
| Almost all acoustic projectors and hydrophones are encapsulated in polymeric materials. These coatings protect the underlying sensors and electronics from physical damage and water ingression, while allowing the passage of acoustical energy without significant reflection, loss, or distortion. Critical material parameters for superior acoustical performance include: (1) density and sound speeds close to those of seawater; (2) low mechanical loss tangent; (3) medium to high shear loss tangent; (4) low ... |
|
| Application of the Biosonar Measurement Tool (BMT) and Instrumented Mine Simulators (IMS) to Exploration of Dolphin Echolocation During Free-Swimming, Bottom-Object Searches |
01-Sep-2003 |
6 pages |
| Authors:
Michael Phillips; Patrick Moore; Dorian S Houser; Stephen Martin; Eric Bauer; SPACE AND NAVAL WARFARE SYSTEMS CENTER PACIFIC SAN DIEGO CA
|
| Bio-inspired signal processing is based on an understanding of an organism's strategy for task completion using a particular sensory modality and the physiological mechanisms underlying the processing of sensory-acquired information. Dolphins possess a biological sonar system that is highly effective at submerged object detection and identification, is operational in open water to very shallow water (VSW) zones, and is capable of finding buried targets. Due to the ability of the ... |
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| Signal Processing Applied to the Dolphin-Based Sonar System |
01-Sep-2003 |
8 pages |
| Authors:
Steve Martin; Patrick Moore; Dorian Houser; Eric Bauer; Mike Pillips; Tim Herrin; BIOMIMETICA SANTEE CA
|
| The bottlenose dolphin has evolved a unique system of biosonar, or echolocation, that allows it to exploit a visually limited littoral niche. The effectiveness of dolphin echolocation at finding and identifying submerged objects is unsurpassed by man-made hardware systems built for similar tasks. It has become a model system from which to draw hardware and signal processing design concepts and is the basis for the development of biomimetic mine-hunting systems ... |
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| Environmentally Adaptive and Through-the-Sensor Efforts at NRL |
SEP 2003 |
12 pages |
| Authors:
Mike Harris; Will Avera; Dale Bibee; Don Walter; Brian Bourgeois; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS MARINE GEOSCIENCES DIV
|
| The Naval Research Laboratory's Marine Geosciences Division is conducting research in Through-The-Sensor and Environmentally Adaptive Sensor Techniques. NRL's AutoSurveyTM system is an environmentally adaptive technique developed to minimize survey time in an area while obtaining the desired seafloor coverage. The effective swath of a multibeam survey system depends on water depth, sound velocity conditions, seafloor properties, and sensor settings. AutoSurvey monitors these conditions and using intelligent navigation adjusts ship track ... |
|
| The NATO TG-25 Unattended Ground Sensors Field Experiment 2002 |
SEP 2003 |
48 pages |
| Authors:
Brian Mays; Hao Vu; Nino Srour; ARMY RESEARCH LAB ADELPHI MD
|
| In October 2002, the U.S. Army Research Laboratory (ARL) participated in the NATO TG-25 unattended ground sensors experiment held in Bourges, France. The field experiment was a joint international signature collection and vehicle tracking exercise with nine participating NATO countries. The experiment consisted of nine different ground vehicles that covered the heavy-tracked, light-tracked, heavy-wheeled, and light-wheeled class of ground vehicles. The vehicles were run in single vehicle and convoy formations. ... |
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| "Follow the Leader" Tracking by Autonomous Underwater Vehicles (AUVs) Using Acoustic Communications and Ranging |
SEP 2003 |
208 pages |
| Authors:
Daniel P. Kucik; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| With advances in computer and sensor technologies, autonomous underwater vehicles (AUVs) are now capable of reaching a level of independent action once thought impossible. Through the use of cooperative behaviors it is possible to further increase their autonomy by allowing multiple operating AUVs to simultaneously coordinate their activities to improve the efficiency and effectiveness of the overall system. This thesis research defines the algorithms and rules needed to perform 'follow ... |
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| Subcritical Detection of Targets Buried Under a Rippled Interface: Calibrated Levels and Effects of Large Roughness |
SEP 2003 |
10 pages |
| Authors:
J. L. Lopes; C. L. Nesbitt; R. Lim; K. L. Williams; E. I. Thorsos; UNIV OF WASHINGTON SEATTLE APPLIED PHYSICS LAB
|
| This paper describes results of an ongoing modeling and measurement effort investigating shallow grazing angle acoustic detection of targets buried in sand. The measurements were performed in a 13.7-meter deep, 110-meter long, 80-meter wide test pool with a 1.5-meter layer of sand on the bottom. A silicone-oil-filled target sphere was buried under a rippled surface with contours formed by raking the sand with a machined rake. Broadband (10 to 50 ... |
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| Contact Depth Localization - Sensitivity to Environmental Variability |
Sep-2003 |
7 pages |
| Authors:
Sudha S Reese; Keith Peters; Mark Vaccaro; NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI
|
| A contact depth recognition technique has been developed which uses the multipath structure of a point target echo and hence the channel structure as a discriminator. The technique uses a template matching approach of predicted multipath structure. Multipath structure is predicted using the Comprehensive Acoustic Sonar Simulator (CASS) model. Inputs to the model, such as sound speed profile, bottom bathymetry and boundary reflection coefficients are modeled using the variability observed ... |
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| Calibrating a 90-kHz Multibeam Sonar |
Sep-2003 |
|
| Authors:
Dezhang Chu; Hufnagle; Lawrence C Jr; Kenneth G Foote; Terence R Hammar; Stephen P Libertore; Kenneth C Baldwin; Larry A Mayer; Andrew McLeod; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| Quantitative use of multibeam sonar requires calibration. Protocols for calibrating multibeam sonar in an absolute sense by means of a standard target are being developed. These protocols are illustrated for the Simrad SM2000 Multibeam Echo Sounder, with 90-kHz operating frequency and 300 beams over a 90-deg sector (+-45 deg), each of nominal beamwidth 1.5x1.5 deg. In a sea well on Iselin Dock at the Woods Hole Oceanographic Institution, directional characteristics ... |
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| Calibrating Two Scientific Echo Sounders |
Sep-2003 |
|
| Authors:
Dezhang Chu; Hufnagle; Lawrence C Jr; Kenneth G Foote; Terence R Hammar; J M Jech; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| The Simrad EK500 has been the state-of-the-art scientific echo sounder for surveying marine fish stocks; the EK60 is its successor. Both echo sounders have been calibrated with the same 38-kHz, 12-deg-beamwidth, split-beam transducer by the standard-target method at the acoustic calibration facility on Iselin Dock at the Woods Hole Oceanographic Institution. The principal measurements were on-axis target strengths and the two-way directivity patterns of the main lobe, measured with a ... |
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| Comparing Two Scientific Echo Sounders |
Sep-2003 |
|
| Authors:
Dezhang Chu; Kenneth G Foote; J M Jech; Stephen P Liberatore; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| The Simrad EK500 and EK60 scientific echo sounders have been operated with the same 38-kHz, 12-deg-beamwidth, split-beam transducer, with alternate pinging by means of an external triggering-and-switching system. The respective performances of the two systems are compared by means of standard-target calibrations conducted at the acoustic calibration facility on Iselin Dock at Woods Hole Oceanographic Institution with a 60-mm-diameter copper sphere. Principal comparisons include those of time series of echo ... |
|
| Synthetic Aperture Sonar on AUV |
Sep-2003 |
6 pages |
| Authors:
Daniel A Cook; Jose E Fernandez; James T Christoff; NAVAL SURFACE WARFARE CENTER DAHLGREN DIV VA
|
| Synthetic aperture sonars (SAS) and autonomous underwater vehicle (AUV) are two of the most exciting technologies under development by the underwater research and development community. Integration of these technologies promises to produce underwater acoustic imaging systems of tremendous capability and versatility. Currently, several efforts, mostly motivated by military applications, are under way to achieve the realization of these systems. This paper describes one such effort, in which the Coastal Systems ... |
|
| Results of a Multi-static Synthetic Aperture Sonar Experiment |
Sep-2003 |
6 pages |
| Authors:
Anthony D Matthews; Victor B Johnson; Randall W Ball; COASTAL SYSTEMS STATION PANAMA CITY FL
|
| It has long been recognized that point targets in synthetic aperture sonar (or radar) imagery could be used to calculate the beamformer coefficients and the motion compensation functions for the system. One difficulty with this approach arises when no point targets are available. Another problem exists in the initial recognition of true point targets, or rather, the automatic separation of point targets from complex targets in the raw data. A ... |
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| Motion Compensation of AUV-Based Synthetic Aperture Sonar |
Sep-2003 |
7 pages |
| Authors:
Daniel A Cook; Jose E Fernandez; James T Christoff; COASTAL SYSTEMS STATION PANAMA CITY FL
|
| To date, ocean-going synthetic aperture sonar (SAS) systems have been deployed exclusively in a configuration where the sonar instrument is housed in a towed body that receives power from and exchanges information with the vessel to which it is attached. Meanwhile, recent years have witnessed the beginnings of maturity with respect to both SAS and autonomous underwater vehicle (AUV) technologies. In order to move away from the towed sonar paradigm, ... |
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| 3-D Acoustic Imaging of Broadband SAS Data |
Sep-2003 |
8 pages |
| Authors:
Jim Christoff; JoEllen Wilbur; Dan Cook; COASTAL SYSTEMS STATION PANAMA CITY FL
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| The difficult conditions encountered in the littoral region require development of flexible sonar processing technologies. One technical approach to increase the flexibility of active sonar has been the development of broadband sonar for multifrequency analysis. Physics based target models of acoustic backscatter use frequency as a prime variable, often defined in terms of radius, a, and acoustic wavenumber, k. For example, fluid filled spheres insonified at low frequencies exhibit sharp ... |
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| Wideband STAP (WB-STAP) for Passive Sonar |
Sep-2003 |
6 pages |
| Authors:
S R Pillai; S U Pillai; J R Guerci; POLYTECHNIC UNIV BROOKLYN NY DEPT OF ELECTRICAL ENGINEERING
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| This paper addresses an innovative method for passive sonar signal processing where it is required to suppress a field of moving acoustic interferes while simultaneously enhancing the signal from a weak moving source. Motivated by the Space-Time Adaptive Processing (STAP) technology for similar radar applications, we propose a solution to the passive broadband sonar problem using Wideband Space-Time Adaptive processing (WB-STAP) in the space-frequency domain. The overall objective is to ... |
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| Specific and Selective Biosensor for Salmonella and Its Detection in the Environment |
15 AUG 2003 |
37 pages |
| Authors:
Eric V. Olsen; AUBURN UNIV AL
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| The specific and selective detection of Salmonella typhymurium based on the use of a polyclonal antibody immobilized by the Langmuir-Blodgett method on the surface a quartz crystal acoustic wave device was demonstrated in liquid samples. These biosensors were selective to Salmonella typhymurium in the presence of large concentrations of Escherichia coli 0157:H7. They were also specific to Salmonella typhymurium since bacteria preincubated with free antibody produced no signal. Dark-field and ... |
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Acoustic Detection and Detectors
