Underwater Wideband Source Localization Using the Interference Pattern Matching

The localization of acoustic source in a shallow water is an important problem in a passive sonar system. For several decades, it has been considered many times over the past years and in order to improve the performance many attempts has been achieved. In order to localize the source in passive sonar system, several methods for a long range source can be categorized into two principles: one is based on the curved-wave-front beamforming, which issued in an array of sonar system. It can not estimate with accuracy because it is not consider multi-path effects in an ocean waveguide. The other is based on the waveguide invariant theory which is recently introduced and researched various areas. The waveguide invariant theory provides a descriptor of the broadband interference pattern on the ocean. The invariant parameter called β which is the slope of the interference pattern is useful for describing the acoustic interference pattern in a waveguide. The range of a source can sometimes also be estimated by the much simpler waveguide invariant method. However the waveguide invariant method requires knowledge of certain ‘invariant’ parameter, which unfortunately often vary significantly with ocean sound speed structure. Recently many methods are proposed using the waveguide invariant theory in passive application and showed the enhanced performance in various area such as MFP based on acoustic propagation model in multi-path environment and a source ranging. But they are still dependent on the β and affect by ocean environment mismatch. So it is necessary to localize the source that independent of the β without the ocean environment information. In this thesis, a source localization using two sensors in an ocean waveguide is proposed. The principle employed for a source localization is based on the IPM(Interference Pattern Matching) algorithm, which uses the unique characteristic of the ocean waveguide. The interference pattern which seen in the sensor spectrogram collected from the moving ship-radiated noise arises from the mutual interference between modes reflected by the surface and the bottom. The interference pattern is directly proportional to the source position by the waveguide invariant theory. If two sensors are used to a source localization in identical acoustic propagation environment, the β has identically effect on the each sensor. Because it is possible to detect the target without regard for β. The proposed IPM algorithm estimates the ratio of each interference pattern from two spectrograms. Therefore the interference pattern ratio between two sensors is the source range ratio. The proposed algorithm requires no knowledge of the ocean environment and independents of the β, although the β varies on the ocean. Finally, the source localization calculates simply the intersection point of two equations which utilized the Appolonius's circle and the time difference. The Appolonius's circle which defined as the locus of a point whose distance from a fixed point is derived the result from the IPM method and estimates the locus of a source using the circle equation. The time difference is derived the TDOA(Time Difference of Arrival) method and estimates the locus of a source using a hyperbolic equation. We performed simulation of 3 scenarios to test the IPM algorithm and localization method proposed in this paper, and then practiced error analysis of the results. And finally we tested performance of a real-data collected during MAPLE-05 experiment applied to the proposed algorithm. In simulation result, the IPM algorithm seemed to have excellent performance whose mean error is within 5%, also the localization performance has similar whose mean error within 10%. In the experimental result, proposed algorithm is even available in real ocean because the estimated position of target shows errors of within 10% which is similar to simulation results. The suggested method can be applied to adapt sufficiently to the field of active sonar and passive sonar using the property of broadband signal.Abstract i List of Figures vi List of Tables x Ⅰ. 서 론 1 Ⅱ. 도파관 불변성 기반의 위치 추정 8 2.1 도파관 불변성 이론 9 2.2 도파관 불변성을 이용한 위치 추정 21 Ⅲ. 2개의 센서를 이용한 음원 위치 추정 24 3.1 간섭패턴매칭에 의한 위치 추정 26 3.2 TDOA에 의한 위치 추정 36 3.3 2개의 방정식을 이용한 음원 위치 추정 40 Ⅳ. 실험 및 고찰 44 4.1 모의실험 및 분석 45 4.2 해상실험 및 분석 65 Ⅴ. 결 론 86 참고문헌 89 부 록 9

Algorithms for propagation-aware underwater ranging and localization

Mención Internacional en el título de doctorWhile oceans occupy most of our planet, their exploration and conservation are one of the crucial research problems of modern time. Underwater localization stands among the key issues on the way to the proper inspection and monitoring of this significant part of our world. In this thesis, we investigate and tackle different challenges related to underwater ranging and localization. In particular, we focus on algorithms that consider underwater acoustic channel properties. This group of algorithms utilizes additional information about the environment and its impact on acoustic signal propagation, in order to improve the accuracy of location estimates, or to achieve a reduced complexity, or a reduced amount of resources (e.g., anchor nodes) compared to traditional algorithms. First, we tackle the problem of passive range estimation using the differences in the times of arrival of multipath replicas of a transmitted acoustic signal. This is a costand energy- effective algorithm that can be used for the localization of autonomous underwater vehicles (AUVs), and utilizes information about signal propagation. We study the accuracy of this method in the simplified case of constant sound speed profile (SSP) and compare it to a more realistic case with various non-constant SSP. We also propose an auxiliary quantity called effective sound speed. This quantity, when modeling acoustic propagation via ray models, takes into account the difference between rectilinear and non-rectilinear sound ray paths. According to our evaluation, this offers improved range estimation results with respect to standard algorithms that consider the actual value of the speed of sound. We then propose an algorithm suitable for the non-invasive tracking of AUVs or vocalizing marine animals, using only a single receiver. This algorithm evaluates the underwater acoustic channel impulse response differences induced by a diverse sea bottom profile, and proposes a computationally- and energy-efficient solution for passive localization. Finally, we propose another algorithm to solve the issue of 3D acoustic localization and tracking of marine fauna. To reach the expected degree of accuracy, more sensors are often required than are available in typical commercial off-the-shelf (COTS) phased arrays found, e.g., in ultra short baseline (USBL) systems. Direct combination of multiple COTS arrays may be constrained by array body elements, and lead to breaking the optimal array element spacing, or the desired array layout. Thus, the application of state-of-the-art direction of arrival (DoA) estimation algorithms may not be possible. We propose a solution for passive 3D localization and tracking using a wideband acoustic array of arbitrary shape, and validate the algorithm in multiple experiments, involving both active and passive targets.Part of the research in this thesis has been supported by the EU H2020 program under project SYMBIOSIS (G.A. no. 773753).This work has been supported by IMDEA Networks InstitutePrograma de Doctorado en Ingeniería Telemática por la Universidad Carlos III de MadridPresidente: Paul Daniel Mitchell.- Secretario: Antonio Fernández Anta.- Vocal: Santiago Zazo Bell

A survey of localization in wireless sensor network

Localization is one of the key techniques in wireless sensor network. The location estimation methods can be classified into target/source localization and node self-localization. In target localization, we mainly introduce the energy-based method. Then we investigate the node self-localization methods. Since the widespread adoption of the wireless sensor network, the localization methods are different in various applications. And there are several challenges in some special scenarios. In this paper, we present a comprehensive survey of these challenges: localization in non-line-of-sight, node selection criteria for localization in energy-constrained network, scheduling the sensor node to optimize the tradeoff between localization performance and energy consumption, cooperative node localization, and localization algorithm in heterogeneous network. Finally, we introduce the evaluation criteria for localization in wireless sensor network

Introducing passive matched field acoustic tomography

In acoustic tomography sea-basin environmental parameters such as temperature profiles and current-velocities are derived, when ray propagation models are adopted, by the travel time estimates relative to the identifiable ray paths. The transmitted signals are either single frequency, or impulsive, or intermittent and deterministic. When the wavelength is comparable with the scale lengths present in the propagation scenario, Matched Field Tomography (MFT) is used, entailing the consideration of waveguide modes instead of rays. A new concept in tomography is introduced in the paper, that employs passively the noise emitted by ships of opportunity (cargoes, ferries) as source signals. The passive technique is acoustic-pollution-free, and if a basin is selected in which a regular ship traffic occurs data can be received on a regular schedule, with no transmission cost. A novel array pre-processor for passive tomography is introduced, such that the signal structure at the pre-processor output is nearly the same as that obtainable in the case of single-frequency source signals. Hence, at the pre-processor output all the tomographic inversion methods valid for active tomography employing single-frequency sources can be applied. The differences between active and passive tomography are pointed out and the potential of passive techniques is illustrated by simple propagation scenarios adopting either rays or waveguide modes

Non-linear echo cancellation - a Bayesian approach

Echo cancellation literature is reviewed, then a Bayesian model is introduced and it is shown how how it can be used to model and fit nonlinear channels. An algorithm for cancellation of echo over a nonlinear channel is developed and tested. It is shown that this nonlinear algorithm converges for both linear and nonlinear channels and is superior to linear echo cancellation for canceling an echo through a nonlinear echo-path channel

A Survey on Subsurface Signal Propagation

Wireless Underground Communication (WUC) is an emerging field that is being developed continuously. It provides secure mechanism of deploying nodes underground which shields them from any outside temperament or harsh weather conditions. This paper works towards introducing WUC and give a detail overview of WUC. It discusses system architecture of WUC along with the anatomy of the underground sensor motes deployed in WUC systems. It also compares Over-the-Air and Underground and highlights the major differences between the both type of channels. Since, UG communication is an evolving field, this paper also presents the evolution of the field along with the components and example UG wireless communication systems. Finally, the current research challenges of the system are presented for further improvement of the WUCs

Ultra Wideband

Ultra wideband (UWB) has advanced and merged as a technology, and many more people are aware of the potential for this exciting technology. The current UWB field is changing rapidly with new techniques and ideas where several issues are involved in developing the systems. Among UWB system design, the UWB RF transceiver and UWB antenna are the key components. Recently, a considerable amount of researches has been devoted to the development of the UWB RF transceiver and antenna for its enabling high data transmission rates and low power consumption. Our book attempts to present current and emerging trends in-research and development of UWB systems as well as future expectations

Design and testing of an acoustic ultra-short baseline navigation system

Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 1992An ultra-short baseline acoustic navigation system has been developed which is capable of determining bearing to a sound source with an error of less than 1° in typical operational conditions. The system has a demonstrated ability to operate in an environment in which multipath interference is significant. A DSP microprocessor is used to process signals received by two hydrophones from a 26 kHz toneburst sound source. This processing power is used to implement features not commonly available with commercial systems. The system has the capability to make an on-line measurement of the signal-tonoise ratio, which can be used to estimate the confidence which should be placed in the data. Estimates of phase difference and signal power are generated many times within each received pulse, so the effects of multi path interference throughout the pulse can be observed. Results of tests at several ranges are presented, and compared to performance models developed in the thesis. System performance is quantified, and an effort is made to understand the effects of multipath arrivals

Signals in the Soil: An Introduction to Wireless Underground Communications

In this chapter, wireless underground (UG) communications are introduced. A detailed overview of WUC is given. A comprehensive review of research challenges in WUC is presented. The evolution of underground wireless is also discussed. Moreover, different component of UG communications is wireless. The WUC system architecture is explained with a detailed discussion of the anatomy of an underground mote. The examples of UG wireless communication systems are explored. Furthermore, the differences of UG wireless and over-the-air wireless are debated. Different types of wireless underground channel (e.g., In-Soil, Soil-to-Air, and Air-to-Soil) are reported as well