Passive Localization
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Optimization Methods For Active And Passive Localization
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Author : Nil Garcia
language : en
Publisher:
Release Date : 2015
Optimization Methods For Active And Passive Localization written by Nil Garcia and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
Active and passive localization employing widely distributed sensors is a problem of interest in various fields. In active localization, such as in MIMO radar, transmitters emit signals that are reflected by the targets and collected by the receive sensors, whereas, in passive localization the sensors collect the signals emitted by the sources themselves. This dissertation studies optimization methods for high precision active and passive localization. In the case of active localization, multiple transmit elements illuminate the targets from different directions. The signals emitted by the transmitters may differ in power and bandwidth. Such resources are often limited and distributed uniformly among the transmitters. However, previous studies based on the well known Cramer-Rao lower bound have shown that the localization accuracy depends on the locations of the transmitters as well as the individual channel gains between different transmitters, targets and receivers. Thus, it is natural to ask whether localization accuracy may be improved by judiciously allocating such limited resources among the transmitters. Using the Cr ́amer-Rao lower bound for target localization of multiple targets as a figure of merit, approximate solutions are proposed to the problems of optimal power, optimal bandwidth and optimal joint power and bandwidth allocation. These solutions are computed by minimizing a sequence of convex problems. The quality of these solutions is assessed through extensive numerical simulations and with the help of a lower-bound that certifies their optimality. Simulation results reveal that bandwidth allocation policies have a stronger impact on performance than power. Passive localization of radio frequency sources over multipath channels is a difficult problem arising in applications such as outdoor or indoor geolocation. Common approaches that combine ad-hoc methods for multipath mitigation with indirect localization relying on intermediary parameters such as time-of-arrivals, time difference of arrivals or received signal strengths, are unsatisfactory. This dissertation models the localization of known waveforms over unknown multipath channels in a sparse framework, and develops a direct approach in which multiple sources are localized jointly, directly from observations obtained at distributed sources. The proposed approach exploits channel properties that enable to distinguish line-of-sight (LOS) from non-LOS signal paths. Theoretical guarantees are established for correct recovery of the sources’ locations by atomic norm minimization. A second-order-cone-based algorithm is developed to produce the optimal atomic decomposition, and it is shown to produce high accuracy location estimates over complex scenes, in which sources are subject to diverse multipath conditions, including lack of LOS.
Passive Localization
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Author : J. V. Candy
language : en
Publisher:
Release Date : 1988
Passive Localization written by J. V. Candy and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1988 with Acoustic models categories.
Smart Passive Localization Using Time Difference Of Arrival
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Author : Noha el Gemayel
language : de
Publisher:
Release Date : 2016
Smart Passive Localization Using Time Difference Of Arrival written by Noha el Gemayel and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Airborne Passive Localization Method Based On Doppler Phase Interference Measuring
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Author : Tao Yu
language : en
Publisher:
Release Date : 2012
Airborne Passive Localization Method Based On Doppler Phase Interference Measuring written by Tao Yu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Technology categories.
Airborne Passive Localization Method Based on Doppler-Phase Interference Measuring.
Passive Localization A Model Base Approach
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Author : J. V. Candy
language : en
Publisher:
Release Date : 1988
Passive Localization A Model Base Approach written by J. V. Candy and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1988 with categories.
Passive localization by use of acoustic propagation models, sometimes called 'Matched Field Processing' is usually carried out in three steps. First some appropriate model is selected, then model parameters (usually taken from archival data or from auxiliary measurements) are introduced into the model. Finally acoustic measurements of the field radiated by the source to be located are made - which, in combination with the properly parametrized model, allow a solution for the source coordinates to be carried out. Here we use such a model-based approach in conjunction with a normal-mode model. By coupling the procedure with a parameter estimation/identification scheme and using a horizontal (towed) array instead of the usual vertical array, we show that the model parameters need not be known a priori in order to carry out the solution. This is in contrast to the standard approach in which the modal functions and wavenumber must be a priori known in order to solve the problem; sufficient information to determine the range of the source can be inferred directly from the measured data themselves. Using a sophisticated acoustic propagation model to generate simulated data, coupled with various array signal processing techniques, the feasibility of the approach is demonstrated. Keywords: Beamforming, Wavenumber estimation. (kr).
Passive Localization Using Propagation Models
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Author : Edmund J. Sullivan
language : en
Publisher:
Release Date : 1987
Passive Localization Using Propagation Models written by Edmund J. Sullivan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1987 with Mathematical models categories.
Passive ranging using propagation models can be effected in two different ways: forward modeling and direct inversion. The forward-modeling method performs an exhaustive recomputation of the field over a set of assumed source locations and seeks the best match to the measured data. The direct inversion method inverts a set of linear equations constituted by the normal mode model. An overview of these two approaches is given along with a summary of studies performed to date. This is followed by the presentation of a maximum-likelihood algorithm for the direct inversion method. A discussion of the merits and weaknesses of each method is given. Also, an appendix which discusses some general aspects of the inverse problem is included.
Localization Of A Moving Source Using Passive Array Data
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Author : E. Weinstein
language : en
Publisher:
Release Date : 1978
Localization Of A Moving Source Using Passive Array Data written by E. Weinstein and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1978 with categories.
Target Localization In Passive And Active Systems
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Author : Vlad Mihai Chiriac
language : en
Publisher:
Release Date : 2012
Target Localization In Passive And Active Systems written by Vlad Mihai Chiriac and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
The main goal of this dissertation is to improve the understanding and to develop ways to predict the performance of localization techniques as a function of signal-to-noise ratio (SNR) and of system parameters. To this end, lower bounds on the maximum likelihood estimator (MLE) performance are studied. The Cramer-Rao lower bound (CRLB) for coherent passive localization of a near-field source is derived. It is shown through the Cramer-Rao bound that, the coherent localization systems can provide high accuracies in localization, to the order of carrier frequency of the observed signal. High accuracies come to a price of having a highly multimodal estimation metric which can lead to sidelobes competing with the mainlobe and engendering ambiguity in the selection of the correct peak. The effect of the sidelobes over the estimator performance at different SNR levels is analyzed and predicted with the use of Ziv-Zakai lower bound (ZZB). Through simulations it is shown that ZZB is tight to the MLEs performance over the whole SNR range. Moreover, the ZZB is a convenient tool to assess the coherent localization performance as a function of various system parameters. The ZZB was also used to derive a lower bound on the MSE of estimating the range and the range rate of a target in active systems. From the expression of the derived lower bound it was noted that, the ZZB is determined by SNR and by the ambiguity function (AF). Thus, the ZZB can serve as an alternative to the ambiguity function (AF) as a tool for radar design. Furthermore, the derivation is extended to the problem of estimating target's location and velocity in a distributed multiple input multiple output (MIMO) radar system. The derived bound is determined by SNR, by the product between the number of transmitting antennas and the number of receiving antennas from the radar system, and by all the ambiguity functions and the cross-ambiguity functions corresponding to all pairs transmitter-target-receiver. Similar to the coherent localization, the ZZB can be applied to study the performance of the estimator as a function of different system parameters. Comparison between the ZZB and the MSE of the MLE obtained through simulations demonstrate that the bound is tight in all SNR regions.
Optimum Element Placement For Passive Localization
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Author : Naval Underwater Systems Center (U.S.)
language : en
Publisher:
Release Date : 1977
Optimum Element Placement For Passive Localization written by Naval Underwater Systems Center (U.S.) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1977 with categories.
Passive Localization Processing For Tactical Unattended Ground Sensors
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Author :
language : en
Publisher:
Release Date : 1995
Passive Localization Processing For Tactical Unattended Ground Sensors written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with categories.
This report summarizes our preliminary results of a development effort to assess the potential capability of a system of unattended ground sensors to detect, classify, and localize underground sources. This report also discusses the pertinent signal processing methodologies, demonstrates the approach with computer simulations, and validates the simulations with experimental data. Specific localization methods discussed include triangulation and measurement of time difference of arrival from multiple sensor arrays.