Download or read book Passive Localization of Underwater Acoustic Beacons written by Dennis Michael Wojcik and published by . This book was released on 1993 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis examines the use of a single, omnidirectional hydrophone as a receiving sensor to passively localize an acoustic beacon. The localization problem is presented as a constrained, nonlinear parameter estimation problem, and Lagrange multipliers are introduced to solve for the maximum likelihood estimate of the acoustic beacon's position. An iterative algorithm is developed using range difference measurements to solve for the maximum likelihood estimate of a stationary acoustic beacon's position. This algorithm is then _extended to include linear, constant velocity motion of the acoustic beacon. Finally, design specifications for a receiver to implement the maximum likelihood estimation algorithms are developed. To test the maximum likelihood estimate algorithms, Monte Carlo simulations are conducted. Results from six representative scenarios are presented. Test results show that as the number of range differences used increases, or the distance that the observer travels between received beacon signals increases, the accuracy of the estimated position improves. Also, tests show that accuracy of the estimated beacon position is directly related to the accuracy in which the observer's position is measured. To test the receiver's design specifications, a prototype receiver is built using commonly available components. It is then shown that the prototype receiver meets or exceeds the design specifications.
Download or read book Passive Localization of an Underwater Acoustic Source Using Directional Sensors written by and published by . This book was released on 1901 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis studies the passive localization (bearing estimation and range and depth estimation) of a single stationary underwater acoustic source in a two-path (direct and surface-reflected path) environment. The main objective of the study is to synthesize and then analyze a passive localization system with a two-receiver (vertically separated) structure that can be supported by a single sonobuoy. Each of the two receivers consists of a cluster of directional sensors uniformly located on a small circle in a horizontal plane. The gain profile of the directional sensors is such that it depends only on bearing of source. Source bearing is estimated from the average signal powers received at two adjacent sensors in one of the two clusters. The focus in the study of bearing estimation is on the feasibility of energy-based bearing estimators. The range and depth information of the source is extracted from the 6 estimated time differences of arrivals (TDOAs) at the two receivers. The emphasis in the study of range and depth estimation is on the correlation among the multipath TDOA estimators and its effect on the prediction of the variance of the time delay-based range and depth estimators. Two algorithms for energy-based bearing estimation are developed. Expressions for the bias and variance of both energy-based bearing estimators are derived. They reveal a fairly simple relationship between the performance of the two bearing estimators and the design parameters (the omnidirectional signal-to-noise ratio and the two receiver parameters). Using the developed expressions can provide good predictions of the bias and variance of the two energy-based bearing estimators in the case of reasonable signal-to-noise ratios. The range and depth estimators are investigated with time delay techniques. Fifteen expressions for the covariance among the six multipath TDOA estimators are derived. It is shown that all six multipath TDOA estimators are correlated and the degree of the corre.
Download or read book Passive Localization of an Underwater Acoustic Source Using Directional Sensors written by and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Embedded Real time Passive Underwater Acoustic Localization System Using a Compact Sensor Array written by Jordin McEachern and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, a passive underwater acoustic localization system using a compact sensor array is developed which receives underwater acoustic sensor data and outputs the position estimations to a map display in real-time. Through simulation, it is evaluated using 130 kHz pulses, which is representative of the harbour porpoise echolocation clicks. The localization system is tested in several environments including the Aquatron, Bay of Fundy, Herring Cove, and New Zealand. The Time Difference of Arrival localization algorithm is used to estimate the position of sound sources using the difference of propagation time between multiple sensors. The implementation also improves upon a traditional grid search by using a lookup table stored in a hyperoctree to reduce the execution time of a position estimation. Additionally, a method to analyze and reduce the estimation error for different sensor geometries is developed. Finally, the impact of noise is mitigated by using various pre-processing techniques.
Download or read book Underwater Acoustic Positioning Systems written by P. H. Milne and published by . This book was released on 1983 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Underwater Acoustic Localization written by Navinda Kottege and published by LAP Lambert Academic Publishing. This book was released on 2011-04 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the advancement of the field of underwater robotics, the amount of autonomy embodied in the vehicles themselves have considerably increased while making it possible to build and deploy swarms of small autonomous underwater vehicles (AUVs). Apart from the many environmental and mechanical challenges encountered in the underwater domain, the swarming paradigm demands the need for each vehicle to be aware of the positions of at least its near neighbours. The Serafina AUV project which was initiated with the goal of developing swarming technology for the small and highly agile Serafina class AUVs requires a localization system which could cope with the dynamic and fast changing vehicle configurations while being small, reliable, robust, and energy efficient and not dependent on pre-deployed acoustic beacons. The acoustical relative localisation system proposed here uses hyperbolic and spherical localization concepts and provides each vehicle with the azimuth, range and heading of its near neighbors.
Download or read book Data driven Localization and Structure Learning in Reverberant Underwater Acoustic Environments written by Toros Arikan and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Passive localization and tracking of a mobile emitter, and the joint learning of its reverberant 3D environment, are important yet challenging tasks in the shallow-water underwater acoustic setting. A typical application is the monitoring of submarines or other man-made emitters with a small, surreptitiously-deployed receiver array. This task can be rendered more difficult by obstacles such as seamounts or piers, which can occlude the line of sight from the emitter to the receivers. Furthermore, the underwater acoustic domain is complex and difficult to model, and a good signal-to-noise ratio is not assured. We view these complexities as features that can be leveraged for improved localization performance, using global optimization and neural network methods. We develop a multi-stage optimization and tracking architecture that precisely maps the reflective boundaries in the environment, and thereby uses the non-line of sight reflected arrivals for robust and accurate localization. Each stage of this architecture establishes domain knowledge such as synchronization and occluder estimation, which are inputs for the following stages of more refined algorithms. Within this framework, we introduce a 2D neural network boundary estimation method that outperforms the existing methods in the literature, and is robust to the large time delay estimation errors that are common in the application domain. We analyze the performance and reliability of this holistic framework, both in simulation and in real-life reverberant watertank testbeds that model the shallow-water underwater acoustic setting. The results are encouraging for the future development of better-performing localization methods with novel capabilities, using data-driven learning algorithms.
Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 38 (thesis year 1993) a total of 13,787 thesis titles from 22 Canadian and 164 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 38 reports theses submitted in 1993, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.
Download or read book Signal Processing for Passive Detection and Classification of Underwater Acoustic Signals written by Kil Woo Chung and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Passive Source Localization Algorithm of an Underwater Sound Source Using Time Difference of Arrival TDOA and Bearing Estimation written by Prithvijit Chattopadhyay and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Signal Processing for Passive Detection and Classification of Underwater Acoustic Signals written by Kil Woo Chung and published by . This book was released on 2011 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Review of Underwater Acoustic Systems and Methods for Locating Objects Lost at Sea written by and published by . This book was released on 1983 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Range dependent Passive Source Localization Using Data from the Barents Sea Tomography Experiment written by David D. Pierce and published by . This book was released on 1996 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Matched-Field Processing (MFP) and Matched-Mode Processing (MMP) are two popular techniques for passively localizing an underwater acoustic emitter in range and depth. One major drawback of these techniques has been their sensitivity to uncertainty concerning the acoustic environment. Several methods for addressing this phenomenon have been proposed in the literature, with varying degrees of success. Achieving high-quality location estimates remains a problem except in simple range-independent experiments or numerical simulations. In this study, we demonstrate an approach for robust, accurate emitter localization in a highly range-dependent real environment using MMP. The main factors contributing to successful localization are: 1) use of the high-resolution Multiple Signal Classification (MUSIC) algorithm, which performs well even when only a few robust modes can be obtained by mode filtering; and 2) use of an acoustic propagation model incorporating mode coupling, which is able to generate accurate replica fields in a strongly range-dependent environment. A secondary objective of the study was to demonstrate the application of higher-order statistical estimation techniques to reduce noise effects. Our results indicate that these techniques show unacceptable sensitivity to noise- and model-induced estimation errors and require further refinement before they will be useful in the underwater acoustic localization problem.
Download or read book Advances in Passive Acoustic Detection Localization and Tracking Applied to Unmanned Underwater Vehicles written by Kristen Railey Kita and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Detection, classification, localization, and tracking (DCLT) of unmanned underwater vehicles (UUVs) in the presence of shipping traffic is a critical task for passive acoustic harbor security systems. In general, vessels can be tracked by their unique acoustic signature due to machinery vibration and cavitation noise. However, cavitation noise of UUVs is considerably quieter than ships and boats, making detection significantly more challenging. In this thesis, I demonstrated that it is possible to passively track a UUV from its highfrequency motor noise using a stationary array in shallow-water experiments with passing boats. First, causes of high frequency tones were determined through direct measurements of two UUVs at a range of speeds. From this analysis, common and dominant features of noise were established: strong tones at the motor’s pulse-width modulated frequency and its harmonics. From the unique acoustic signature of the motor, I derived a high-precision, remote sensing method for estimating propeller rotation rate. In shallow-water UUV field experiments, I demonstrated that detecting a UUV from motor noise, in comparison to broadband noise from the vehicle, reduces false alarms from 45% to 8.4% for 90% true detections. Beamforming on the motor noise, in comparison to broadband noise, improved the bearing accuracy by a factor of 3.2×. Because the signal is also high-frequency, the Doppler effect on motor noise is observable and I demonstrate that range rate can be measured. Furthermore, measuring motor noise was a superior method to the “detection of envelope modulation on noise” algorithm for estimating the propeller rotation rate. Extrapolating multiple measurements from the motor signature is significant because Bearing-Doppler-RPM measurements outperform traditional bearing-Doppler target motion analysis. In the unscented Kalman filter implementation, the tracking solution accuracy for bearing, bearing rate, range, and range rate improved by a factor 2.2×, 15.8×, 3.1×, and 6.2× respectively. These findings are significant for improving UUV localization and tracking, and for informing the next-generation of quiet UUV propulsion systems.
Download or read book OFDM for Underwater Acoustic Communications written by Sheng Zhou and published by John Wiley & Sons. This book was released on 2014-03-21 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt: A blend of introductory material and advanced signal processing and communication techniques, of critical importance to underwater system and network development This book, which is the first to describe the processing techniques central to underwater OFDM, is arranged into four distinct sections: First, it describes the characteristics of underwater acoustic channels, and stresses the difference from wireless radio channels. Then it goes over the basics of OFDM and channel coding. The second part starts with an overview of the OFDM receiver, and develops various modules for the receiver design in systems with single or multiple transmitters. This is the main body of the book. Extensive experimental data sets are used to verify the receiver performance. In the third part, the authors discuss applications of the OFDM receiver in i) deep water channels, which may contain very long separated multipath clusters, ii) interference-rich environments, where an unintentional interference such as Sonar will be present, and iii) a network with multiple users where both non-cooperative and cooperative underwater communications are developed. Lastly, it describes the development of a positioning system with OFDM waveforms, and the progress on the OFDM modem development. Closely related industries include the development and manufacturing of autonomous underwater vehicles (AUVs) and scientific sensory equipment. AUVs and sensors in the future could integrate modems, based on the OFDM technology described in this book. Contents includes: Underwater acoustic channel characteristics/OFDM basics/Peak-to-average-ratio control/Detection and Doppler estimation (Doppler scale and CFO)/Channel estimation and noise estimation/A block-by-block progressive receiver and performance results/Extensions to multi-input multi-output OFDM/Receiver designs for multiple users/Cooperative underwater OFDM (Physical layer network coding and dynamic coded cooperation)/Localization with OFDM waveforms/Modem developments A valuable resource for Graduate and postgraduate students on electrical engineering or physics courses; electrical engineers, underwater acousticians, communications engineers
Download or read book Passive Acoustic Localization and Tracking Using Arrays and Directional Sensors written by Ludovic Tenorio-Hallé and published by . This book was released on 2021 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: In bioacoustics, passive acoustic localization and tracking plays an important role in studying marine mammals and other organisms that produce underwater sounds. However, the implementation of such techniques faces many practical challenges, such as lack of environmental data for accurately modeling acoustic propagation, uncertainties in sensor position, time-synchronization of autonomous instruments, and logistical constraints due to large arrays. The three research chapters of this dissertation cumulatively address these hurdles. Chapter 2 develops a reformulation of the "double-difference" method for long-range tracking of acoustic sources. Originally developed for high-resolution localization of earthquakes across a network of widely distributed sensor, the double-difference approach is here adapted to exploit acoustic multipath on a vertical array, deployed in a deep-water waveguide. Results are shown to provide high-precision relative depth and range tracks of sources on the order of 50 km away, by compensating for biases caused by underdetermined array tilt and sound speed model. The method is demonstrated on both a towed acoustic source and a sperm whale (Physeter macrocephalus). Chapter 3 presents a passive time-synchronization technique for independent autonomous acoustic recorders. This approach relies on the coherent ambient noise sources maintaining the same statistical angular distribution around the instruments. Under this assumption, the temporal evolution of the cross-correlation function between sensor pairs reveals their relative time drift. This method enables continuous measurements of clock offset, including small-scale non-linear fluctuations of the drift, otherwise unobservable with standard time-synchronization techniques. Data from a field study in San Ignacio Lagoon, Mexico, is used to demonstrate this technique which is here applied to low frequency pulses, most likely originating from croaker fish (Sciaenidae family). Chapter 4 uses acoustic vector sensor data to track multiple sources simultaneously. The method is demonstrated on singing humpback whales (Megaptera novaeangliae) off western Maui. Here, the directional capabilities of vector sensors are exploited to identify and match azimuthal tracks from multiple sources between sensors, yielding localized whale tracks in terms of latitude and longitude over time. This approach shows potential for further applications such as tracking boats and analyzing the directional properties of ambient noise field.
Download or read book Observations of Near bottom Flow in a Wave dominated Nearshore Environment written by J. J. Fredericks and published by . This book was released on 1994 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt:
