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 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 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 Machine Learning in Passive Ocean Acoustics for Localizing and Characterizing Events written by Emma Ozanich and published by . This book was released on 2020 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: Passive acoustics, or the recording of pressure signals from uncontrolled sound sources, is a powerful tool for monitoring man-made and natural sounds in the ocean. Passive acoustics can be used to detect changes in physical processes within the environment, study behavior and movement of marine animals, or observe presence and motion of ocean vessels and vehicles. Advances in ocean instrumentation and data storage have improved the availability and quality of ambient noise recordings, but there is an ongoing effort to improve signal processing algorithms for extracting useful information from the ambient noise. This dissertation uses machine learning as a framework to address problems in underwater passive acoustic signal processing. Statistical learning has been used for decades, but machine learning has recently gained popularity due to the exponential growth of data and its ability to capitalize on these data with efficient GPU computation. The chapters within this dissertation cover two types of problems: characterization and classification of ambient noise, and localization of passive acoustic sources. First, ambient noise in the eastern Arctic was studied from April to September 2013 using a vertical hydrophone array as it drifted from near the North Pole to north of Fram Strait. Median power spectral estimates and empirical probability density functions (PDFs) along the array transit show a change in the ambient noise levels corresponding to seismic survey airgun occurrence and received level at low frequencies and transient ice noises at high frequencies. Noise contributors were manually identified and included broadband and tonal ice noises, bowhead whale calling, seismic airgun surveys, and earthquake T phases. The bowhead whale or whales detected were believed to belong to the endangered Spitsbergen population and were recorded when the array was as far north as 86°24'N. Then, ambient noise recorded in a Hawaiian coral reef was analyzed for classification of whale song and fish calls. Using automatically detected acoustic events, two clustering processes were proposed: clustering handpicked acoustic metrics using unsupervised methods, and deep embedded clustering (DEC) to learn latent features and clusters from fixed-length power spectrograms. When compared on simulated signals of fish calls and whale song, the unsupervised clustering methods were confounded by overlap in the handpicked features while DEC identified clusters with fish calls, whale song, and events with simultaneous fish calls and whale song. Both clustering approaches were applied to recordings from directional autonomous seafloor acoustic recorder (DASAR) sensors on a Hawaiian coral reef in February 2020. Next, source localization in ocean acoustics was posed as a machine learning problem in which data-driven methods learned source ranges or direction-of-arrival directly from observed acoustic data. The pressure received by a vertical linear array was preprocessed by constructing a normalized sample covariance matrix (SCM) and used as the input for three machine learning methods: feed-forward neural networks (FNN), support vector machines (SVM) and random forests (RF). The FNN, SVM, RF and conventional matched-field processing were applied to recordings from ships in the Noise09 experiment to demonstrate the potential of machine learning for underwater source localization. The source localization problem was extended by examining the relationship between conventional beamforming and linear supervised learning. Then, a nonlinear deep feedforward neural network (FNN) was developed for direction-of-arrival (DOA) estimation for two-source DOA and for K-source DOA, where K is unknown. With multiple snapshots, K-source FNN achieved resolution and accuracy similar to Multiple Signal Classification (MUSIC) and SBL for an unknown number of sources. The practicality of the deep FNN model was demonstrated on ships in the Swellex96 experimental data.

Download or read book Underwater Acoustic Signal Processing written by Douglas A. Abraham and published by Springer. This book was released on 2019-02-14 with total page 860 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides comprehensive coverage of the detection and processing of signals in underwater acoustics. Background material on active and passive sonar systems, underwater acoustics, and statistical signal processing makes the book a self-contained and valuable resource for graduate students, researchers, and active practitioners alike. Signal detection topics span a range of common signal types including signals of known form such as active sonar or communications signals; signals of unknown form, including passive sonar and narrowband signals; and transient signals such as marine mammal vocalizations. This text, along with its companion volume on beamforming, provides a thorough treatment of underwater acoustic signal processing that speaks to its author’s broad experience in the field.

Download or read book Localization in Underwater Sensor Networks written by Jing Yan and published by Springer Nature. This book was released on 2021-10-27 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ocean covers 70.8% of the Earth’s surface, and it plays an important role in supporting all life on Earth. Nonetheless, more than 80% of the ocean’s volume remains unmapped, unobserved and unexplored. In this regard, Underwater Sensor Networks (USNs), which offer ubiquitous computation, efficient communication and reliable control, are emerging as a promising solution to understand and explore the ocean. In order to support the application of USNs, accurate position information from sensor nodes is required to correctly analyze and interpret the data sampled. However, the openness and weak communication characteristics of USNs make underwater localization much more challenging in comparison to terrestrial sensor networks. In this book, we focus on the localization problem in USNs, taking into account the unique characteristics of the underwater environment. This problem is of considerable importance, since fundamental guidance on the design and analysis of USN localization is very limited at present. To this end, we first introduce the network architecture of USNs and briefly review previous approaches to the localization of USNs. Then, the asynchronous clock, node mobility, stratification effect, privacy preserving and attack detection are considered respectively and corresponding localization schemes are developed. Lastly, the book’s rich implications provide guidance on the design of future USN localization schemes. The results in this book reveal from a system perspective that underwater localization accuracy is closely related to the communication protocol and optimization estimator. Researchers, scientists and engineers in the field of USNs can benefit greatly from this book, which provides a wealth of information, useful methods and practical algorithms to help understand and explore the ocean.

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 Localization of Acoustic Transients in Shallow Water Environments written by Charles Louis Nicholson and published by . This book was released on 1992 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ocean observation based on underwater acoustic technology written by Xuebo Zhang and published by Frontiers Media SA. This book was released on 2023-07-04 with total page 281 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 Acoustic Source Localization written by Nilu Zhao and published by . This book was released on 2016 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many technologies rely on underwater acoustics. Most of these applications are able to denoise Gaussian noise from the surrounding, but have trouble removing impulse like noises. One source of impulse-like noise is the snapping shrimps. The acoustic signals they emit from snapping their claws hinder technologies, but can also be used as a source of ambient noise illumination due to the rough uniformity in their spatial distribution. Understanding the spatial distributions of these acoustic signals can be useful in working to mitigate or amplify their effects. Our collaborators in Singapore use a multi-array sensor to take measurements of the sound pressures of the environment in the ocean. This thesis investigates in solving the signal reconstruction problem -- given the measurements, reconstruct the locations of the original signal sources. A numerical model for the system consisting of the snapping shrimp signals, the environment, and the sensor is formulated. Three methods of reconstruction -- Disciplined Convex Programming, Orthogonal Matching Pursuit, and Compressive Sensing -- are explored, and their robustness to noise, and sparsity are examined in simulation. Results show that Two-Step Iterative Shrinkage Threshold (TwIST) is the most robust to noisy and non-sparse signals. The three methods were then tested on real data set, in which OMP and TwIST showed promising consistency in their results, while CVX was unable to converge. Since there is no available information on ground truth, the consistency is a promising result.

Download or read book Applied Underwater Acoustics written by Thomas Neighbors and published by Elsevier. This book was released on 2017-01-19 with total page 982 pages. Available in PDF, EPUB and Kindle. Book excerpt: Applied Underwater Acoustics meets the needs of scientists and engineers working in underwater acoustics and graduate students solving problems in, and preparing theses on, topics in underwater acoustics. The book is structured to provide the basis for rapidly assimilating the essential underwater acoustic knowledge base for practical application to daily research and analysis. Each chapter of the book is self-supporting and focuses on a single topic and its relation to underwater acoustics. The chapters start with a brief description of the topic's physical background, necessary definitions, and a short description of the applications, along with a roadmap to the chapter. The subtopics covered within individual subchapters include most frequently used equations that describe the topic. Equations are not derived, rather, assumptions behind equations and limitations on the applications of each equation are emphasized. Figures, tables, and illustrations related to the sub-topic are presented in an easy-to-use manner, and examples on the use of the equations, including appropriate figures and tables are also included. - Provides a complete and up-to-date treatment of all major subjects of underwater acoustics - Presents chapters written by recognized experts in their individual field - Covers the fundamental knowledge scientists and engineers need to solve problems in underwater acoustics - Illuminates, in shorter sub-chapters, the modern applications of underwater acoustics that are described in worked examples - Demands no prior knowledge of underwater acoustics, and the physical principles and mathematics are designed to be readily understood by scientists, engineers, and graduate students of underwater acoustics - Includes a comprehensive list of literature references for each chapter

Download or read book Underwater Signal and Data Processing written by Joseph C. Hassab and published by CRC Press. This book was released on 2018-01-18 with total page 371 pages. Available in PDF, EPUB and Kindle. Book excerpt: A systematic and integrated account of signal and data processing with emphasis on the distinctive marks of the ocean environment is provided in this informative text. Underwater problems such as space-time processing relations vs. disjointed ones, processing of passive observations vs. active ones, time delay estimation vs. frequency estimation, channel effects vs. transparent ones, integrated study of signal, data, and channel processing vs. separate ones, are highlighted. The book provides the beginner with a concise presentation of the essential concepts, defines the basic computational steps, and gives the mature reader an advanced view of underwater systems and the relationships among their building blocks. It presents the needed topics on applied estimation theory within the underwater systems context. Included are topics in linear and nonlinear filtering, spectral analysis, generalized correlation, cepstrum and complex demodulation, Cramer-Rao Bounds, maximum likelihood, weighted least-squares, Kalman filtering, expert systems, wave propagation and their use, as well as their performance in applications to canonical ocean problems. The applications center on the definition, analysis, and solution implementations to representative underwater signal analysis problems dealing with signals estimation, their location and motion. The potential limitations and pitfalls of the implementations are delineated in homogeneous, noisy, interfering, inhomogeneous, multipath, distortions, and/or dispersive channels.

Download or read book Advances in Sound Localization written by Pawel Strumillo and published by IntechOpen. This book was released on 2011-04-11 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sound source localization is an important research field that has attracted researchers' efforts from many technical and biomedical sciences. Sound source localization (SSL) is defined as the determination of the direction from a receiver, but also includes the distance from it. Because of the wave nature of sound propagation, phenomena such as refraction, diffraction, diffusion, reflection, reverberation and interference occur. The wide spectrum of sound frequencies that range from infrasounds through acoustic sounds to ultrasounds, also introduces difficulties, as different spectrum components have different penetration properties through the medium. Consequently, SSL is a complex computation problem and development of robust sound localization techniques calls for different approaches, including multisensor schemes, null-steering beamforming and time-difference arrival techniques. The book offers a rich source of valuable material on advances on SSL techniques and their applications that should appeal to researches representing diverse engineering and scientific disciplines.

Download or read book Underwater Acoustic Data Processing written by Y. T. Chan and published by Springer Science & Business Media. This book was released on 1989-03-31 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the papers that were accepted for presentation at the 1988 NATO Advanced Study Institute on Underwater Acoustic Data Processing, held at the Royal Military College of Canada from 18 to 29 July, 1988. Approximately 110 participants from various NATO countries were in attendance during this two week period. Their research interests range from underwater acoustics to signal processing and computer science; some are renowned scientists and some are recent Ph.D. graduates. The purpose of the ASI was to provide an authoritative summing up of the various research activities related to sonar technology. The exposition on each subject began with one or two tutorials prepared by invited lecturers, followed by research papers which provided indications of the state of development in that specific area. I have broadly classified the papers into three sections under the titles of I. Propagation and Noise, II. Signal Processing and III. Post Processing. The reader will find in Section I papers on low frequency acoustic sources and effects of the medium on underwater acoustic propagation. Problems such as coherence loss due to boundary interaction, wavefront distortion and multipath transmission were addressed. Besides the medium, corrupting noise sources also have a strong influence on the performance of a sonar system and several researchers described methods of modeling these sources.

Download or read book Advances in Sound Localization written by Pawel Strumillo and published by BoD – Books on Demand. This book was released on 2011-04-11 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sound source localization is an important research field that has attracted researchers' efforts from many technical and biomedical sciences. Sound source localization (SSL) is defined as the determination of the direction from a receiver, but also includes the distance from it. Because of the wave nature of sound propagation, phenomena such as refraction, diffraction, diffusion, reflection, reverberation and interference occur. The wide spectrum of sound frequencies that range from infrasounds through acoustic sounds to ultrasounds, also introduces difficulties, as different spectrum components have different penetration properties through the medium. Consequently, SSL is a complex computation problem and development of robust sound localization techniques calls for different approaches, including multisensor schemes, null-steering beamforming and time-difference arrival techniques. The book offers a rich source of valuable material on advances on SSL techniques and their applications that should appeal to researches representing diverse engineering and scientific disciplines.