Дисертації з теми "GNSS Techniques"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-46 дисертацій для дослідження на тему "GNSS Techniques".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Casile, Roberta <1986>. "GNSS interference management techniques against malicious attacks." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7025/1/Casile_Roberta_tesi.pdf.
Повний текст джерелаCasile, Roberta <1986>. "GNSS interference management techniques against malicious attacks." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7025/.
Повний текст джерелаEgea-Roca, Daniel. "Change detection techniques for GNSS signal-level integrity." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/458425.
Повний текст джерелаThe provision of accurate positioning is becoming essential to our modern society. One of the main reasons is the great success and ease of use of Global Navigation Satellite Systems (GNSSs), which has led to an unprecedented amount of GNSS-based applications. In particular, the current trend shows that a new era of GNSS-based applications and services is emerging. These applications are the so-called critical applications, in which the physical safety of users may be in danger due to a miss-performance of the system. These applications have stringent requirements in terms of integrity, which is a measure of reliability and trust that can be placed on the information provided by the system. Unfortunately, GNSS-based critical applications are usually associated with terrestrial environments and original integrity algorithms usually fail. The main impairments are due to local effects such as interference, multipath or spoofing, which are assumed to be controlled in civil aviation but they are not in terrestrial environments. Thus, a new methodology for integrity is necessary in order to detect local effects and provide the additional level of integrity needed for GNSS-based critical applications; the so-called signal-level integrity. This thesis investigates novel detection algorithms with the aim of providing a new generation of integrity techniques in GNSS. For this purpose, the framework of Statistical Change Detection (SCD) is considered. This framework is of particular interest because its optimal criterion target the temporal dimension. This is an indispensable requirement for critical applications, in which a prompt detection is necessary. Therefore, the first part of this dissertation deals with the study of the field of SCD, including both Quickest Change Detection (QCD) and Transient Change Detection (TCD). Novel contributions are provided in the field of TCD, including the finite moving average solution and its statistical characterization. Numerical results show the superiority of our contributions. Finally, to conclude our study of SCD we compare it with classical detection schemes under the same mathematical framework. This comparison shows the appropriateness of SCD when dealing with timely detections. The main contribution of this thesis is the application of the SCD framework to threat detection and integrity in GNSS. To this end, we first investigate several properties of the received GNSS signal that may be useful for local threat detection. This leads us to move a step forward in the field of threat detection by proposing a novel QCD-based framework. Nonetheless, for integrity purposes a bounded delay is desirable, and it is here where TCD is of interest. For this reason, a novel TCD-based framework is considered for both multipath detection and integrity algorithms in GNSS, thus leading to the provision of signal-level integrity. A notable improvement is shown by the proposed TCD-based solutions considered in this thesis with respect to current solutions. In the last part of the thesis, the goal is to validate the proposed threat detectors and signal-level integrity algorithm using real GNSS signals. Real signal gathered in the context of an EC-funded research project is processed to show and validate the results of the implemented detectors. The results obtained in a realistic scenario show the improvement of the accuracy and integrity by using the proposed solution for signal-level integrity, with respect to current integrity algorithms. Furthermore, the proposed solution is shown to have real-time processing capabilities, thus being very attractive to improve current integrity algorithms and easily implementable in mass-market receivers.
Ferreira, Esteves Paulo Alexandre. "Techniques d'acquisition à haute sensibilité des signaux GNSS." Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0016/document.
Повний текст джерелаSatellite navigation (GNSS) is a constant in our days. The number of applications that depend on it is already remarkable and is constantly increasing. With new applications, new challenges have also risen: much of the new demand for signals comes from urban areas where GNSS signal processing is highly complex. In this thesis the issue of weak GNSS signal processing is addressed, in particular at the first phase of the receiver processing, known as signal acquisition. The first axe of research pursued deals with the analysis and compensation of the Doppler effect in acquisition. The Doppler shift that is experienced by a user is one of the main design drivers for the acquisitionmodule and solutions are proposed to improve the sensitivity-complexity trade-off typical of the acquisition process. The second axe of research deals with the characterization of differential GNSS detectors. After a first step of coherent integration, transition to post coherent (noncoherent or differential) integration is required for acquiring weak signals. The quantification of the sensitivity of differential detectors was not found in literature and is the objective of this part of the research. Finally, the third axe of research is devoted to multi-constellation Collective Detection (CD). CD is an innovative approach for the simultaneous processing of all signals in view. Severalissues related to CD are addressed, including the improvement of the CD search process and the hybridization with standard acquisition. Finally, the application of this methodology in the context of a multi-constellation receiver is also addressed, by processing simultaneously real GPS and Galileo signals
GARBIN, MANFREDINI ESTEBAN. "Signal processing techniques for GNSS anti-spoofing algorithms." Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2672749.
Повний текст джерелаNGUYEN, DINH THUAN. "ROBUST SIGNAL PROCESSING TECHNIQUES FOR MODERN GNSS RECEIVERS." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2752881.
Повний текст джерелаGómez, Casco David. "Non-Coherent Acquisition Techniques for High-Sensitivity GNSS Receivers." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/665404.
Повний текст джерелаGlobal Navigation Satellite Systems (GNSSs) have become an indispensable tool of daily life, since they offer us the possibility of accurately knowing our location in real time and in open-sky environments. Since the advent of these systems, a large number of successful GNSS applications have emerged. Some examples of these applications are: car navigation, flight tracking, sport activity tracking and augmented reality games. Due to the success achieved by GNSS, a great interest is emerging to extend its services to harsher environments such as urban canyons and indoor scenarios. However, in these environments GNSS receivers face great difficulties to detect the signals received from the satellites, which are very weak since they suffer from severe attenuation due to the presence of obstacles in the propagation path between satellites and the receiver. This thesis addresses several problems of processing weak GNSS signals, such as the detection at the acquisition stage, the determination of their signal quality and the time delay and Doppler frequency estimations. To do so, detection and estimation tools are used, which are based on the probability theory and statistics. In order to use these tools, it is necessary to understand the architecture and the signals that GNSSs transmit. For this reason, the first part of the thesis focuses on describing the main features of two of the best-known GNSSs, the American GPS and the European Galileo. In addition, we describe the fundamentals of the receivers and analyze the signals that are implemented in these systems. After that, we explain the required fundamentals of detection theory, namely the Neyman-pearson criterion, the Generalized Likelihood Ratio Test and the Bayesian approach. Then, a review of the state of the art in the detection of GNSS signals is carried out. The main contribution of this thesis is provided in the second part, which tackles the problem of deriving optimal detectors to acquire weak GNSS signals. We have found that the optimal detector depends on the characteristics of the signal transmitted by the satellite, which is different depending on the selected constellation. The theoretical and simulated results show that the detectors proposed in this thesis clearly outperform the detectors currently used in practice. In addition, we conclude when it is better to apply each detector. Moreover, this thesis addresses the problem of estimating the carrier-to-noise ratio of weak GNSS signals. This parameter provides essential information since it is used in all stages of GNSS receivers. In this thesis, we propose new estimators of the carrier-to-noise ratio, which are very simple to implement in high-sensitivity GNSS receivers and offer an enhanced accuracy with respect to the estimators proposed in the literature. Finally, the last part of the thesis focuses on the so-called high-order binary offset carrier (BOC) signals, a kind of signal that is implemented in the Galileo system. More precisely, this part is devoted to proposing accurate estimators of time delay and Doppler frequency. These estimators improve the accuracy of the method usually applied in practice to estimate these parameters.
Albu-Rghaif, Ali. "Multi-GNSS signals acquisition techniques for software defined receivers." Thesis, University of Buckingham, 2015. http://bear.buckingham.ac.uk/105/.
Повний текст джерелаBaños, García Adrián. "Use of precise point positioning techniques in GNSS applications." Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-76090.
Повний текст джерелаTANG, XINHUA. "Development and Analysis of Advanced Techniques for GNSS Receivers." Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2546939.
Повний текст джерелаBuchanan, Matthew L. "Investigation of Advanced Spaceborne GNSS-R Techniques Usingthe SMAP Satellite." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1565890319858178.
Повний текст джерелаSeals, Kelly Charles. "Enhanced Acquisition Techniques for GPS L1C Receivers." Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-dissertations/71.
Повний текст джерелаLocubiche-Serra, Sergi. "Robust Carrier Tracking Techniques for GNSS Receivers affected by Ionospheric Scintillation." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/668304.
Повний текст джерелаGlobal Navigation Satellite Systems (GNSS) have become an indispensable tool in different areas in our modern society for positioning purposes using radio-frequency ranging signals. Some application examples are the positioning and navigation in ground, maritime and aviation environments, as well as their use in agriculture, surveying and precise timing and synchronization in communication systems and finances. The tracking stage is one of the core tasks within a GNSS receiver to keep aligned with the satellites and, to date, most receivers equip conventional tracking techniques with ease of implementation that suffice to operate in environments with favorable working conditions. However, in the recent years, the success of GNSS in open-sky environments has led to the emergence of applications that expand toward scenarios with harsher conditions, such as urban canyons and soft-indoor environments. The trend is to provide user mobile terminals such as smartphones with positioning capabilities in scenarios where receivers face new technological challenges owing to the abounding propagation impairments. In this sense, the so-called ionospheric scintillation is one of the issues degrading the performance of GNSS receivers, particularly in equatorial regions and at high latitudes. It introduces rapid carrier phase and signal power variations, and has a detrimental effect particularly onto the tracking stage. The objective of this thesis is to design and develop new techniques for the robust tracking of GNSS signals affected by ionospheric scintillation disturbances. The presented approach is based on the use of Kalman filtering techniques, and the main contributions of the thesis are three. First, the analysis of ionospheric scintillation and the tracking of carrier dynamics despite the presence of the former. We design a Kalman filter with a hybrid formulation that allows the robust monitoring of both contributions separately. This arises from carrying out a detailed analysis of ionospheric scintillation which concludes that scintillation phase variations can be characterized through autoregressive processes, and thus be dealt with within the Kalman filter in a natural manner. Second, the design of adaptive Kalman filter-based techniques that allow self-adjusting their loop bandwidth to the actual scintillation conditions, which are rather time-varying in practice. This part includes a scintillation detector, a real-time estimator of the autoregressive model parameters, and an implementation to address the problem of non-linear signal amplitude attenuation introduced by scintillation itself. The goodness of the proposed techniques is later validated by carrying out an extensive simulation campaign using both synthetic data and real scintillation time series, and the outperformance region with respect to conventional tracking techniques is quantified. Third, a novel method for the derivation of expressions for the termed Bayesian Cramér-Rao bound (BCRB), which allow characterizing the behavior of Kalman filters in a closed-form manner, thus becoming a contribution to the literature of practical usefulness to design Kalman filters for any kind of application.
ROMERO, GAVIRIA RODRIGO MANUEL. "Estimation Techniques and Mitigation Tools for Ionospheric effects on GNSS Receivers." Doctoral thesis, Politecnico di Torino, 2015. http://hdl.handle.net/11583/2616928.
Повний текст джерелаBERARDO, MATTIA. "GNSS Integrity Monitoring assisted by Signal Processing techniques in Harsh Environments." Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2675456.
Повний текст джерелаClosas, Gómez Pau. "Bayesian signal processing techniques for GNSS receivers: from multipath mitigation to positioning." Doctoral thesis, Universitat Politècnica de Catalunya, 2009. http://hdl.handle.net/10803/6942.
Повний текст джерелаEl disseny d'un receptor per a GNSS consta d'un seguit de blocs funcionals. Començant per l'antena receptora fins al càlcul final de la posició del receptor, el disseny proporciona una gran motivació per a la recerca en diversos àmbits. Tot i que la cadena de Radiofreqüència del receptor també és comentada a la tesis, l'objectiu principal de la recerca realitzada recau en els algorismes de processament de senyal emprats un cop realitzada la digitalització del senyal rebut. En un receptor per a GNSS, aquests algorismes es poden dividir en dues classes: els de sincronisme i els de posicionament. Aquesta classificació correspon als dos grans processos que típicament realitza el receptor. Primer, s'estima la distancia relativa entre el receptor i el conjunt de satèl·lits visibles. Aquestes distancies es calculen estimant el retard patit pel senyal des de que és emès pel corresponent satèl·lit fins que és rebut pel receptor. De l'estimació i seguiment del retard se n'encarrega l'algorisme de sincronisme. Un cop calculades la distancies relatives als satèl·lits, multiplicant per la velocitat de la llum el retards estimats, l'algorisme de posicionament pot operar. El posicionament es realitza típicament pel procés de trilateralització: intersecció del conjunt d'esferes centrades als satèl·lits visibles i de radi les distancies estimades relatives al receptor GNSS. Així doncs, sincronització i posicionament es realitzen de forma seqüencial i ininterrompudament. La tesi fa contribucions a ambdues parts, com explicita el subtítol del document.
Per una banda, la tesi investiga l'ús del filtrat Bayesià en el seguiment dels paràmetres de sincronisme (retards, desviaments Doppler i phases de portadora) del senyal rebut. Una de les fonts de degradació de la precisió en receptors GNSS és la presència de repliques del senyal directe, degudes a rebots en obstacles propers. És per això que els algorismes proposats en aquesta part de la tesi tenen com a objectiu la mitigació de l'efecte multicamí. La dissertació realitza una introducció dels fonaments teòrics del filtrat Bayesià, incloent un recull dels algorismes més populars. En particular, el Filtrat de Partícules (Particle Filter, PF) s'estudia com una de les alternatives més interessants actualment per a enfrontar-se a sistemes no-lineals i/o no-Gaussians. Els PF són mètodes basats en el mètode de Monte Carlo que realitzen una caracterització discreta de la funció de probabilitat a posteriori del sistema. Al contrari d'altres mètodes basats en simulacions, els PF tenen resultats de convergència que els fan especialment atractius en casos on la solució òptima no es pot trobar. En aquest sentit es proposa un PF que incorpora un seguit de característiques que el fan assolir millors prestacions i robustesa que altres algorismes, amb un nombre de partícules reduït. Per una banda, es fa un seguiment dels estats lineals del sistema mitjançant un Filtre de Kalman (KF), procediment conegut com a Rao-Blackwellization. Aquest fet provoca que la variància de les partícules decreixi i que un menor nombre d'elles siguin necessàries per a assolir una certa precisió en l'estimació de la distribució a posteriori. D'altra banda, un dels punts crítics en el disseny de PF és el disseny d'una funció d'importància (emprada per a generar les partícules) similar a l'òptima, que resulta ésser el posterior. Aquesta funció òptima no està disponible en general. En aquesta tesi, es proposa una aproximació de la funció d'importància òptima basada en el mètode de Laplace. Paral·lelament es proposen algorismes com l'Extended Kalman Filter (EKF) i l'Unscented Kalman Filter (UKF), comparant-los amb el PF proposat mitjançant simulacions numèriques.
Per altra banda, la presentació d'un nou enfocament al problema del posicionament és una de les aportacions originals de la tesi. Si habitualment els receptors operen en dos passos (sincronització i posicionament), la proposta de la tesi rau en l'Estimació Directa de la Posició (Direct Position Estimation, DPE) a partir del senyal digital. Tenint en compte la novetat del mètode, es proporcionen motivacions qualitatives i quantitatives per a l'ús de DPE enfront al mètode convencional de posicionament. Se n'ha estudiat l'estimador de màxima versemblança (Maximum Likelihood, ML) i un algorisme per a la seva implementació pràctica basat en l'algorisme Accelerated Random Search (ARS). Els resultats de les simulacions numèriques mostren la robustesa de DPE a escenaris on el mètode convencional es veu degradat, com per exemple el cas d'escenaris rics en multicamí. Una de les reflexions fruit dels resultats és que l'ús conjunt dels senyals provinents dels satèl·lits visibles proporciona millores en l'estimació de la posició, doncs cada senyal està afectada per un canal de propagació independent. La tesi també presenta l'extensió de DPE dins el marc Bayesià: Bayesian DPE (BDPE). BDPE manté la filosofia de DPE, tot incloent-hi possibles fonts d'informació a priori referents al moviment del receptor. Es comenten algunes de les opcions com l'ús de sistemes de navegació inercials o la inclusió d'informació atmosfèrica. Tot i així, cal tenir en compte que la llista només està limitada per la imaginació i l'aplicació concreta on el marc BDPE s'implementi.
Finalment, la tesi els límits teòrics en la precisió dels receptors GNSS. Alguns d'aquests límits teòrics eren ja coneguts, d'altres veuen ara la llum. El límit de Cramér-Rao (Cramér-Rao Bound, CRB) ens prediu la mínima variància que es pot obtenir en estimar un paràmetre mitjançant un estimador no esbiaixat. La tesi recorda el CRB dels paràmetres de sincronisme, resultat ja conegut. Una de les aportacions és la derivació del CRB de l'estimador de la posició pel cas convencional i seguint la metodologia DPE. Aquests resultats proporcionen una comparativa asimptòtica dels dos procediments pel posicionament de receptors GNSS. D'aquesta manera, el CRB de sincronisme pel cas Bayesià (Posterior Cramér-Rao Bound, PCRB) es presenta, com a límit teòric dels filtres Bayesians proposats en la tesi.
This dissertation deals with the design of satellite-based navigation receivers. The term Global Navigation Satellite Systems (GNSS) refers to those navigation systems based on a constellation of satellites, which emit ranging signals useful for positioning. Although the american GPS is probably the most popular, the european contribution (Galileo) will be operative soon. Other global and regional systems exist, all with the same objective: aid user's positioning. Initially, the thesis provides the state-of-the-art in GNSS: navigation signals structure and receiver architecture. The design of a GNSS receiver consists of a number of functional blocks. From the antenna to the final position calculation, the design poses challenges in many research areas. Although the Radio Frequency chain of the receiver is commented in the thesis, the main objective of the dissertation is on the signal processing algorithms applied after signal digitation. These algorithms can be divided into two: synchronization and positioning. This classification corresponds to the two main processes typically performed by a GNSS receiver. First, the relative distance between the receiver and the set of visible satellites is estimated. These distances are calculated after estimating the delay suffered by the signal traveling from its emission at the corresponding satellite to its reception at the receiver's antenna. Estimation and tracking of these parameters is performed by the synchronization algorithm. After the relative distances to the satellites are estimated, the positioning algorithm starts its operation. Positioning is typically performed by a process referred to as trilateration: intersection of a set of spheres centered at the visible satellites and with radii the corresponding relative distances. Therefore, synchronization and positioning are processes performed sequentially and in parallel. The thesis contributes to both topics, as expressed by the subtitle of the dissertation.
On the one hand, the thesis delves into the use of Bayesian filtering for the tracking of synchronization parameters (time-delays, Doppler-shifts and carrier-phases) of the received signal. One of the main sources of error in high precision GNSS receivers is the presence of multipath replicas apart from the line-of-sight signal (LOSS). Wherefore the algorithms proposed in this part of the thesis aim at mitigating the multipath effect on synchronization estimates. The dissertation provides an introduction to the basics of Bayesian filtering, including a compendium of the most popular algorithms. Particularly, Particle Filters (PF) are studied as one of the promising alternatives to deal with nonlinear/nonGaussian systems. PF are a set of simulation-based algorithms, based on Monte-Carlo methods. PF provide a discrete characterization of the posterior distribution of the system. Conversely to other simulation-based methods, PF are supported by convergence results which make them attractive in cases where the optimal solution cannot be analytically found. In that vein, a PF that incorporates a set of features to enhance its performance and robustness with a reduced number of particles is proposed. First, the linear part of the system is optimally handled by a Kalman Filter (KF), procedure referred to as Rao-Blackwellization. The latter causes a reduction on the variance of the particles and, thus, a reduction on the number of required particles to attain a given accuracy when characterizing the posterior distribution. A second feature is the design of an importance density function (from which particles are generated) close to the optimal, not available in general. The selection of this function is typically a key issue in PF designs. The dissertation proposes an approximation of the optimal importance function using Laplace's method. In parallel, Extended Kalman Filter (EKF) and Unscented Kalman Filter (UKF) algorithms are considered, comparing these algorithms with the proposed PF by computer simulations.
On the other hand, a novel point of view in the positioning problem constitutes one of the original contributions of the thesis. Whereas conventional receivers operate in a two-steps procedure (synchronization and positioning), the proposal of the thesis is a Direct Position Estimation (DPE) from the digitized signal. Considering the novelty of the approach, the dissertation provides both qualitative and quantitative motivations for the use of DPE instead of the conventional two-steps approach. DPE is studied following the Maximum Likelihood (ML) principle and an algorithm based on the Accelerated Random Search (ARS) is considered for a practical implementation of the derived estimator. Computer simulation results carried show the robustness of DPE in scenarios where the conventional approach fails, for instance in multipath-rich scenarios. One of the conclusions of the thesis is that joint processing of satellite's signals provides enhance positioning performances, due to the independent propagation channels between satellite links. The dissertation also presents the extension of DPE to the Bayesian framework: Bayesian DPE (BDPE). BDPE maintains DPE's philosophy, including the possibility of accounting for sources of side/prior information. Some examples are given, such as the use of Inertial Measurement Systems and atmospheric models. Nevertheless, we have to keep in mind that the list is only limited by imagination and the particular applications were BDPE is implemented. Finally, the dissertation studied the theoretical lower bounds of accuracy of GNSS receivers. Some of those limits were already known, others see the light as a result of the research reported in the dissertation. The Cramér-Rao Bound (CRB) is the theoretical lower bound of accuracy of any unbiased estimator of a parameter. The dissertation recalls the CRB of synchronization parameters, result already known. A novel contribution of
the thesis is the derivation of the CRB of the position estimator for either conventional and DPE approaches. These results provide an asymptotical comparison of both GNSS positioning approaches. Similarly, the CRB of synchronization parameters for the Bayesian case (Posterior Cramér-Rao Bound, PCRB) is given, used as a fundamental limit of the Bayesian filters proposed in the thesis.
Marchán, Hernandez Juan Fernando. "Sea state determnation using GNSS-R techniques: contributions to the PAU instrument." Doctoral thesis, Universitat Politècnica de Catalunya, 2009. http://hdl.handle.net/10803/6932.
Повний текст джерелаLa presente tesis doctoral describe el trabajo desarrollado entre 2004 y 2008 en aspectos tanto teóricos como de implementación hardware dentro del campo de la reflectometría GNSS. Más concretamente, el capítulo 1 introduce brevemente la recuperación de SSS mediante teledetección y describe el proyecto PAU. Por su parte, el capítulo 2 esta dedicado a los fundamentos de la reflectometría GNSS, mientras que el capítulo 3 hace hincapié en el observable GNSS-R elegido, el delay-Doppler Map (DDM) completo. Así, se presenta una nueva y eficiente aproximación a la simulación de DDMs junto a las clásicas expresiones de Zavorotny-Voronovich para la señal GNSS dispersada. Posteriormente se estudia la parametrización de DDMs en el capítulo 4, donde algunos de los parámetros derivados son subsecuentemente relacionados con el estado del mar. Por otro lado, en el capítulo 5 se ofrece una descripción pormenorizada del diseño, implementación y validación del un reflectómetro capaz de generar DDMs en tiempo real basado en un dispositivo FGPA, mientras que en el capítulo 6 se presenta la campaña de medidas ALBATROSS 08, donde se utilizó el instrumento PAU-GNSS/R desarrollado para verificar la idoneidad de los parámetros GNSS-R propuestos para describir el estado del mar. Finalmente, las conclusiones y el trabajo futuro se consignan en el capítulo 7.
With the upcoming launch of the ESA's Soil Moisture and Ocean Salinity (SMOS) mission, the retrieval of Sea Surface Salinity (SSS) from space will benefit both the oceanography and climatology communities. However, the impact of the sea roughness on the radiometric measurement has to be accurately modeled and accounted for first, so that to reduce the induced error on the retrieved SSS and yield meaningful values. In recent years the use of reflected Global Navigation Satellite System Signals (GNSS-R) has shown its potential to retrieve geophysical parameters, mainly altimetry and more recently sea state. The approach consisted of comparing the measured waveform (correlation at different delays) with a modeled one. One of the rationales that motivated the submission of the Passive Advanced Unit (PAU) project to the EURYI foundation was to study the direct relationship between the radiometric brightness temperature and some to-be-defined GNSS-R observables by obtaining co-located measurements with an L-band radiometer and a GPS reflectometer, and perform the actual SSS retrieval with the aid of an infrared radiometer. The PAU project has been developed by the Passive Remote Sensing Group of the Remote Sensing Lab, at the Department of Signal Theory and Communications of the Universitat Politènica de Catalunya.
The present PhD dissertation describes the work undertaken between 2004 and 2008 in both theoretical and hardware issues within the field of GNSS-R reflectometry. More specifically, in chapter 1 a brief introduction to SSS retrieval is given along with the description of the PAU project. Chapter 2 is devoted to the basics of GNSS reflectometry, whereas chapter 3 is focused into the simulation of the chosen GNSS-R observable, the whole Delay-Doppler Map (DDM). A new approach to DDM simulation is introduced along with the review of the classical implementation of the Zavorotny-Voronovich expressions for the reflected GNSS signal. After that, the parameterization of the DDMs is studied in chapter 4, where some of the derived parameters are to be linked to the actual sea state. Chapter 5 offers a detailed description of the design, implementation and validation of a real- time FPGA-based DDM reflectometer, whereas chapter 6 describes the ALBATROSS 08 measurement campaign, where the developed PAU-GNSS/R was tested. The conclusions and the future work are listed in chapter 7.
Kuratomi, Alejandro. "GNSS Position Error Estimated by Machine Learning Techniques with Environmental Information Input." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-262692.
Повний текст джерелаInom Intelligenta transportsystem (ITS), specifikt för självkörande fordon, så är en exakt fordonspositionering en nödvändighet för ökad trafiksäkerhet. Positionsnoggrannheten beror på estimering av både positionen samt positionsfelet. Olika tekniker och tillämpningar som siktar på att förbättra positionsfeluppskattningen behövs, vilket det nu forskas kring. Denna uppsats undersöker olika maskininlärningsalgoritmer inriktade på estimering av positionsfel. Algoritmerna utvärderar relevant information från en GNSS-mottagare, samt information från en kamera om den kringliggande miljön. En GNSS-mottagare och kamera monterades på en radiostyrd mobil testplattform för insamling av data. Examensarbetet består av två delar. Första delen innehåller träning och testning av valda maskininlärningsalgoritmer med GNSS-data tillhandahållen av Waysure från tester gjorda under 2016. Denna data inkluderar ingen information från den omkringliggande miljön runt GNSS-mottagaren. Andra delen består av träning och testning av valda maskininlärningsalgoritmer på GNSS-data som kommer från nya tester gjorda under maj 2019, vilka inkluderar miljöinformation runt GNSS-mottagaren. Resultaten från båda delar analyseras. De viktigaste egenskaper som erhålls från en trädbaserad modell, algoritmens beslutsträd, presenteras. Slutsatsen från denna rapport är att det inte går att statistiskt säkerställa att inkludering av information från den omkringliggande miljön från en kamera förbättrar noggrannheten vid estimering av positionsfelet med de valda maskininlärningsmodellerna.
Raimondi, Mathieu. "Développement et caractérisation de techniques de réduction d’interférences pulsées pour récepteurs GNSS embarqués." Toulouse, INSA, 2008. http://eprint.insa-toulouse.fr/archive/00000275/.
Повний текст джерелаCivil Aviation standardisation bodies (ICAO, RTCA, EUROCAE) are currently investigating the use of the Global Navigation Satellite System (GNSS) as a stand-alone navigation solution for civil aircraft. For obvious safety reasons, on-board GNSS receivers must guarantee minimum performance requirements in given phases of flights. These requirements, dependent upon the system and signals used, are stated in the Minimum Operational Performance Specification (MOPS), published (or being published) by the corresponding authorities. With that respect, the future use of Galileo E5 and GPS L5 bands has raised, among others, interference issues. Indeed, pre-existent RF systems emit in this band, thus interfering with the E5/L5 signals. The main threat was identified as being DME/TACAN ground beacons pulsed emissions. Without any mitigation capability, these systems can disturb the proper operation of on-board GNSS receivers, preventing them from complying with safety requirements. Two Interference Mitigation Techniques (IMT) have been proposed to fight this threat, the Temporal Blanker and the Frequency Domain Interference Suppressor (FDIS). The Temporal Blanker technique offers a fairly simple implementation and was shown to provide enough benefits to ensure that the specified requirements were met in all phases of flight for a GPS L5 or Galileo E5 receiver. However, it was also demonstrated that the resulting performances were meeting the requirements by only a small margin on the worst DME/TACAN interference environment that can be found in Europe and USA, so called the European and USA “hot spots”. In contrast, the FDIS is a more demanding mitigation technique against pulsed interference in terms of required resources but improves the performances of the receiver, thus allowing larger margins with respect to the civil aviation requirements. The core of the study is the analysis of the performances of GNSS receivers using FDIS as IMT. The dissertation architecture is the following: first, the navigation signals, Galileo E5a/E5b and GPS L5, as long as the interferences that constitute a threat for GNSS navigation and their impact on GNSS receivers operations are presented. Then, a description of the studied IMTs (Temporal Blanker, FDIS), their theoretical characteristics and the theoretical derivations of the post-correlation C/N0 degradation suffered by a receiver using these techniques in presence of pulsed interference are depicted. Afterwards, all the results obtained concerning the IMTs performance assessments are presented. Firstly, the Figures Of Merit chosen to analyze the performance of both techniques are presented and their choice is motivated. Then, the chosen interference and signal scenarios, along with the simulation tools and means are finely detailed. Finally, a confrontation of Temporal Blanker and FDIS performances is given using the previously described FOMs. The conclusion summarizes the performances analysis, compares them to - 6 - civil aviation performances requirements, and proposes recommendations for on-board GNSS receivers design
Flohrer, Claudia. "Mutual validation of satellite-geodetic techniques and its impact on GNSS orbit modeling /." Bern : [s.n.], 2008. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
Повний текст джерелаRoudier, Marion. "Définition de signaux et de techniques de traitement innovants pour les futurs systèmes GNSS." Thesis, Toulouse, INPT, 2015. http://www.theses.fr/2015INPT0044/document.
Повний текст джерелаGlobal Navigation Satellite Systems (GNSS) are increasingly present in our everyday life. Further operational needs are emerging, mainly in urban environments. In these obstructed environments, the signal emitted by the satellite is severely degraded due to the many obstacles. Consequently, the data demodulation and the user position calculation are difficult. GNSS signals being initially designed in an open environment context, their demodulation performance is thus generally studied in the associated AWGN propagation channel model. But nowadays, GNSS signals are also used in degraded environments. It is thus essential to provide and study their demodulation performance in urban propagation channel models. It is in this context that this PhD thesis is related, the final goal being to improve GNSS signals demodulation performance in urban areas, proposing a new signal. In order to be able to provide and study GNSS signals demodulation performance in urban environments, a simulation tool has been developed in this PhD thesis context: SiGMeP for ‘Simulator for GNSS Message Performance'. It allows simulating the entire emission/reception GNSS signal chain in urban environment. Existing and modernized signals demodulation performance has thus been computed with SiGMeP in urban environments. In order to represent this demodulation performance faithfully to reality, a new methodology adapted to urban channels is proposed in this dissertation. Then, to improve GNSS signals demodulation performance in urban environments, the research axis of this thesis has focused on the ‘Channel Coding' aspect. In order to decode the transmitted useful information, the receiver computes a detection function at the decoder input. But the detection function used in classic receivers corresponds to an AWGN propagation channel. This dissertation thus proposes an advanced detection function which is adapting to the propagation channel where the user is moving. This advanced detection function computation considerably improves demodulation performance, just in modifying the receiver part of the system. Finally, in order to design a new signal with better demodulation performance in urban environments than one of existing and future signals, a new LDPC channel code has been optimized for a CSK modulation. Indeed, the CSK modulation is a promising modulation in the spread spectrum signals world, which permits to free from limitation sin terms of data rate implied by current GNSS signals modulations
Legru, Benoît. "Mesure de déformation par combinaison de techniques géodésiques : Auscultation par GPS et topométrie." Phd thesis, Conservatoire national des arts et metiers - CNAM, 2011. http://tel.archives-ouvertes.fr/tel-00736511.
Повний текст джерелаZoulida, Myriam. "Determination of terrestrial frames by optimal combination of GNSS, DORIS and SLR measurements." Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC050.
Повний текст джерелаIn the present approach used to produce the International Terrestrial Reference Frame (ITRF), observations of the different space geodetic techniques are reduced in independent analyses. The only mean to tie the resulting technique-specific frames into a homogeneous combined frame is then to use local topometric ties between stations of different techniques co-located at the same observatory. However, inconsistencies between these local ties and space geodesy estimates of the station positions are today a major limiting factor of the ITRF quality. An alternative way of tying the different space geodetic techniques together is through the use of multitechnique satellites equipped with instruments of more than one technique. The main challenge of using such a satellite as an inter-technique link resides in the accurate knowledge (or estimation) of the vectors between the satellite's center of mass and the reference points of its different instruments (i. E. Space ties). In this thesis we present the results from multi-technique (GPS+SLR+DORIS) analyses involving the Jason-2 satellite, and we compare them to the results from traditional single-technique analyses. We assess in particular the effect of simultaneously processing the observations of the three techniques with Jason-2 as inter-technique link on the resolution of the GPS phase ambiguities, on the estimation of the GPS and Jason-2 satellite orbits and on the estimation of the ground station positions. Moreover, results of the estimation of the Jason-2 space ties are presented, in order to assess the quality of the presently available values
Lima, Daniel Valle de. "Multipath mitigation in time-delay estimation via tensorbased techniques for antenna array-based gnss receivers." reponame:Repositório Institucional da UnB, 2017. http://repositorio.unb.br/handle/10482/23730.
Повний текст джерелаSubmitted by Raquel Almeida (raquel.df13@gmail.com) on 2017-06-19T19:41:18Z No. of bitstreams: 1 2017_DanielVoltedeLima.pdf: 996662 bytes, checksum: 36ce9f105c83e143c174dac8585b777d (MD5)
Approved for entry into archive by Raquel Viana (raquelviana@bce.unb.br) on 2017-06-23T18:16:56Z (GMT) No. of bitstreams: 1 2017_DanielVoltedeLima.pdf: 996662 bytes, checksum: 36ce9f105c83e143c174dac8585b777d (MD5)
Made available in DSpace on 2017-06-23T18:16:56Z (GMT). No. of bitstreams: 1 2017_DanielVoltedeLima.pdf: 996662 bytes, checksum: 36ce9f105c83e143c174dac8585b777d (MD5) Previous issue date: 2017-06-23
Clientes de Sistemas Globais de Navegação por Satélites, do inglês Global Navigation Satellite System (GNSS), dependem da estimação do atraso para estimar a posição do usuário. [1] Isto é feito fazendo a correlação do sinal recebido com sequências-réplicas para separar o sinal de cada satélite e estimar o atraso. Como componentes de multipercurso são cópias atrasadas do sinal original, estes alteram a função de correlação cruzada, assim gerando erros na estimação de atraso. Nesta dissertação estudamos um algoritmo estado-da-arte em mitigação de multipercursos para estimação de atraso baseado no autofiltro da decomposição em valores singular de alta ordem, do inglês Higher-Order Singular Value Decomposition (HOSVD), de posto unitário, [2] e propomos dois esquemas tensoriais para mitigação de multipercurso e estimação de atraso, para qual o esquema baseado em HOSVD é usado para comparação. O primeiro esquema tensorial é um método em três etapas que aplica estimação da direção de chegada, do inglês Direction of Arrival (DoA), e fatorização Khatri-Rao, do inglês Khatri-Rao factorization (KRF), para separar o código de cada componente incidente de forma fechada. O segundo esquema calcula uma matrix de covariância multimodo como aproximação do desdobramento Hermitian duplamente simétrico [3] com qual, alternando entre a solução do problema ortogonal de Procrustes, do inglês Orthogonal Procrustes Problem (OPP), [4] e fatorização Khatri-Rao de mínimos quadrados, do inglês Least Squares Khatri-Rao Factorization (LSKRF), [5] se estima iterativamente as matrizes-fator do canal, que são então usadas para separar o código de cada componente incidente. Ambos esquemas geram resultados melhores que o estado-da-arte baseado no autofiltro de alta ordem.
Global Navigation Satellite System (GNSS) clients rely on time-delay estimation to estimate a user’s position. [1] This is done by correlating the incoming signal with replica sequences to separate each satellite and perform time-delay estimation. Since multipath components are delayed copies of the original signal, this affects the cross-correlation function, thus impacting time-delay estimation. 1 In this thesis, we study a state-of-the-art approach for multipath mitigation time-delay estimation algorithm based on the rank-one Higher-Order Singular Value Decomposition (HOSVD) eigenfilter, [2] and propose two tensorbased schemes for multipath mitigation and time-delay estimation, for which the HOSVD-based scheme is a basis of comparison. The first scheme is a three step tensor-based approach applying direction of arrival (DoA) estimation and Khatri-Rao factorization (KRF) to separate the code for each impinging component in a closed fashion. The second approach calculates a multimode covariance matrix as an approximation of the dualsymmetric Hermitian unfolding [3] with which, by alternating between a solution to the orthogonal Procrustes problem (OPP) [4] and least squares Khatri-Rao factorization, [5] iteratively estimates the channel factor matrices which are then used to separate the code of each impinging component. Both our schemes outperforms the HOSVD-based eigenfilter state-of-the-art solution.
Isioye, Olalekan Adekunle. "An Investigation of Ground-Based GNSS Atmospheric Remote Sensing Techniques for Weather and Climate Monitoring in Nigeria." Thesis, University of Pretoria, 2017. http://hdl.handle.net/2263/60814.
Повний текст джерелаThesis (PhD)--University of Pretoria, 2017.
Geography, Geoinformatics and Meteorology
PhD
Unrestricted
MUSUMECI, LUCIANO. "Advanced signal processing techniques for interference removal in Satellite Navigation Systems." Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2550137.
Повний текст джерелаBin, Syed Mohd Dardin Syed Mohd Fairuz. "Étude d'algorithmes de poursuite du signal GNSS permettant d'améliorer le positionnement en environnement urbain." Thesis, Toulouse, ISAE, 2015. http://www.theses.fr/2015ESAE0008/document.
Повний текст джерелаPresent research activities in the field of Global Navigation Satellite Systems (GNSS) aim atenhancing the overall navigation performance by providing better and more robust navigationsignals compared the ones available today. These GNSS signals are designed to provide betterimproved cross-correlation protection, lower tracking thresholds and reduced susceptibility tonarrow band interferences. However navigation based on GNSS signals remains sensitive topropagation impairments such as reflection, refraction, diffraction and scattering, and sometimesblockage of the line of sight signals. These effects are especially important in urban environment.Therefore, a better and more robust receiver design and implementation is crucial to meet anappropriate navigation performance using GNSS signals. Improving signal tracking algorithms inside the receiver is an attractive approach. This is particularly true in the case of urban environments where interference and multipath severely degrade the performance of the GPS positioning. Despite the many efforts of performance enhancement, multipath still remains as the dominant source of error and the limiting factor for many applications. Consequently improving the performance of a receiver in multipath environment is a great challenge and many studies are carried out to satisfy the above requirements in term of availability, reliability and integrity. The main goal of this PhD thesis is to propose a new adaptive tracking algorithm based on vector tracking loop (VTL) approach. Currently, the conventional technique (i.e., Scalar Tracking Loop (STL)) is implemented in a forward-only strategy which doesn’t exploit the position, velocity and time (PVT) solution provided by the Navigation System (NS). Standard VTL on the other hand, suffers from measurements contamination from the exploitation of PVT provided by the NS. This adaptiveapproach will take advantage of both tracking methods for providing reliable measurements in amulti-constellation context
Homelius, Marcus. "Tracking of Ground Vehicles : Evaluation of Tracking Performance Using Different Sensors and Filtering Techniques." Thesis, Linköpings universitet, Reglerteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-148432.
Повний текст джерелаLi, Xingxing [Verfasser], Harald [Akademischer Betreuer] Schuh, Maorong [Akademischer Betreuer] Ge, and Frank [Akademischer Betreuer] Flechtner. "Real-time high-rate GNSS techniques for earthquake monitoring and early warning / Xingxing Li. Gutachter: Frank Flechtner. Betreuer: Harald Schuh ; Maorong Ge." Berlin : Technische Universität Berlin, 2015. http://d-nb.info/1075807514/34.
Повний текст джерелаTranchant, Yann-Treden. "Vers une meilleure exploitation de l’altimétrie côtière : apports combinés de la modélisation hydrodynamique à haute-résolution et des nouvelles techniques de cartographie du niveau marin par GNSS." Thesis, La Rochelle, 2022. http://www.theses.fr/2022LAROS014.
Повний текст джерелаSatellite altimetry has recently reached an unprecedented level of accuracy and coverage. Although altimeters were originally designed to observe the oceans and have improved our understanding of their large-scale dynamics, the exploitation in coastal areas remains a challenge. One of the challenges of coastal altimetry remains the lack of precision in geophysical corrections, which are essential to compute accurate sea level anomalies near the coast. The main objective of this thesis is to develop new methodologies based on mobile sea level GNSS measurements and hydrodynamic modelling in order to better exploit altimetry measurements in coastal environments and to prepare the arrival of future missions. During a campaign carried out with the PAMELi marine drone in July 2020 in the Pertuis Charentais, a sea-level cartography was carried out along a pre-programmed route. In a first study, this cartography is used to assess a tidal model under an altimetric pass, and thus demonstrate the potential of a drone to extend spatially our validation capabilities. Then, the same dataset is used to estimate the geoid slopes in the region, by combining in-situ measurements and the hydrodynamic model. We show that the use of our model to correct the dynamic topography gradients improves drastically the coherence and the accuracy of geoid slopes. These two studies exploit a methodology based on crossover height differences, and offer perspectives on the use of autonomous platforms in the context of the future SWOT mission. In a last chapter, a coastline prediction method based on the use of a DEM and the hydrodynamic model is presented, and applied to Sentinel-3A passages in order to evaluate the impact of intertidal areas on altimeter measurements. This overall thesis work provides methodological insights for a better understanding and exploitation of altimetry measurements in coastal environments, and will help to prepare the scientific exploitation of the future SWOT mission
Sicramaz, Ayaz Ayse Verfasser], Bernd [Akademischer Betreuer] [Eissfeller, and Wolfgang [Akademischer Betreuer] Gerstacker. "Weak and Degraded Signal Acquisition Techniques in GNSS Software Receiver / Ayse Sicramaz Ayaz. Universität der Bundeswehr München, Fakultät für Luft- und Raumfahrttechnik. Gutachter: Bernd Eissfeller ; Wolfgang Gerstacker. Betreuer: Bernd Eissfeller." Neubiberg : Universitätsbibliothek der Universität der Bundeswehr München, 2014. http://d-nb.info/1054300070/34.
Повний текст джерелаAttia, Dhouha. "Segmentation d'images par combinaison adaptative couleur-texture et classification de pixels. : Applications à la caractérisation de l'environnement de réception de signaux GNSS." Thesis, Belfort-Montbéliard, 2013. http://www.theses.fr/2013BELF0209/document.
Повний текст джерелаColor and texture are two main information used in image segmentation. The first contribution of this thesis focuses on the joint use of color and texture information by developing a robust and non parametric method combining color and texture gradients. The proposed color/texture combination allows defining a structural gradient that is used as potential image in watershed algorithm. The originality of the proposed method consists in studying a 3D points cloud generated by color and texture descriptors, followed by an eigenvalue analysis. The color/texture combination method is firstly tested and compared with well known methods in the literature, using two databases (generic BERKELEY database of color images and the VISTEX database of texture images). The applied part of the thesis is within ViLoc project (funded by RFC regional council) and CAPLOC project (funded by PREDIT). In this framework, the second contribution of the thesis concerns the characterization of the environment of GNSS signals reception. In this part, we aim to improve estimated position of a mobile in urban environment by excluding NLOS satellites (for which the signal is masked or received after reflections on obstacles surrounding the antenna environment). For that, we propose two approaches to characterize the environment of GNSS signals reception using image processing. The first one consists in applying the proposed color/texture combination on images acquired in mobility with a fisheye camera located on the roof of a vehicle and oriented toward the sky. The segmentation step is followed by a binary classification to extract two classes « sky » (LOS signals) and « not sky » (NLOS signals). The second approach is proposed in order to satisfy the real-time constraint required by the application. This approach is based on image simplification and adaptive pixel classification. The NLOS satellites exclusion principle is interesting, in terms of improving precision of position, when the LOS satellites (for which the signals are received directly) are well geometrically distributed in space. To take into account the knowledge of satellite distribution and then increase the precision of position, we propose a new strategy of position estimation, based on the exclusion of NLOS satellites (identified by the image processing step), conditioned by DOP information, which is provided by GPS data
Daly, Shannen. "Implementation of a State-of-the-Art GNSS Receiver Autonomous Integrity Monitoring Technique." Thesis, West Virginia University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10844210.
Повний текст джерелаThis thesis implements a state-of-the-art solution separation advanced RAIM (ARAIM) algorithm as it is written as reported in the literature. Specifically, a GNSS fault detection and exclusion algorithm for a multi-constellation GNSS was implemented in software and tested against simulated data. RAIM algorithms have been created in many forms over the last couple of decades and are still in development today. The position solution results produced by this ARAIM algorithm were compared to that of a snapshot weighted least squares (WLS) solution in which failed satellites are removed before processing and an WLS solution with no corrections applied. In addition, the difference in position solution between ARAIM and the simulation truth was compared to the ARAIM reported horizontal and vertical protection limits, as well as, the position performance criteria. This thesis also investigates the performance of the exclusion method and how it affects the performance of the overall ARAIM algorithm. The algorithm implemented and tested in this thesis will be used as a basis of comparison for on-going research into robust GNSS processing techniques.
Lu, Ye. "Positioning in GNSS-challenged environments : design framework, algorithms and technologies." Thesis, Evry, Institut national des télécommunications, 2015. http://www.theses.fr/2015TELE0020.
Повний текст джерелаWhile the human beings explore the nature tirelessly, they also put significant concerns to be aware of themselves, to know better of the circumstances, and to be informed with their precise positions, velocities, trajectories, and so on, in local environments. The Global Navigation Satellite Systems (GNSS) have provided an efficient method to do so outdoors, and have already become an indispensable assistant of many people. After the success of GPS and GLONASS, Galileo and BeiDou are currently under deployment, offering more choices of the independent or collaborative positioning. However, the GNSS signal is vulnerable to obstructions: almost no GNSS services are available inside buildings, tunnels, or underground parkings; the services are not always coherent in urban canyons. In order to address this problem, this thesis is dedicated to the design frameworks for the positioning in GNSS-challenged environments, as well as the corresponding algorithms and technologies. A brief survey of the latest radio-based and inertial positioning/tracking systems is provided. Among the feasible technologies, the discussion is centered on but not limited to the GNSS-based approach, which is due to the inherited advantages of this approach and also the deep engagement of our research group in this domain. We have, on one hand, explored the possibility and limitations on the centimeter-accuracy positioning with our Repealite system (i.e. a GNSS-base indoor positioning system with specific features); on the other hand, a method of batch localization for the nodes in a network of dynamic communicating objects is proposed, which is originated from an issue of the GNSS-based approach - the resolution of the receiver initial point, but then it goes beyond the scope of the “classical” GNSS-based approach
Munghemezulu, Cilence. "Determination of geodetic velocity field parameters for the African tectonic plate using the technique of Global Navigation Satellite Systems." Diss., University of Pretoria, 2013. http://hdl.handle.net/2263/40360.
Повний текст джерелаDissertation (MSc)--University of Pretoria, 2013.
gm2014
Geography, Geoinformatics and Meteorology
unrestricted
Guandalini, Marcos. "Análise metodológica do posicionamento relativo através do GNSS e suas aplicações na engenharia: uso da técnica RTK/GSM." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/3/3138/tde-17062013-145658/.
Повний текст джерелаThe use of Global Navigation Satellite System has dramatically grown over the last decade. Currently, GNSS receivers are secure, efficient and highly productive for carrying out observations for the geodetic coordinates determination on the Earth\'s surface. The tools and technologies available on the market are essential in the establishment of engineering projects. However, the total knowledge of the techniques and the total domain of the execution methods are the first obstacles to the full incorporation of the technology in the engineering projects. This work is to clarify and to teste the technology described in this dissertation related to the facilities of cell phone coverage, particularly the GSM/GPRS connection able to be used in Brazil. The precise positioning in real-time traditionally involves the transmission of phase measurements between base and rover GNSS receivers; this is traditionally carried out through radio frequencies. This allows determining geodetic and topographic coordinates instantaneously. However, obstacles like accident topography terrain, buildings or low power of radio basis transmission, provoke constant interruptions in the communication among the radios and the consequent losing of the instant solution. Nevertheless, this methodology is the most productive for a centimetric accuracy; so the major challenge in geodetic positioning is to overcome the mentioned difficulties. With the high development of technologies related to mobile phone, a new way to transmit the observations using the GSM/GPRS connection was created. The GSM connection is a standard mobile technology, the most popular for cell phones, which became of easy access to any person. The traditional RTCM protocol in a convenient format can be transmitted by GSM/GPRS connection which is known as NTRIP service, becoming a full digital communication system. As of this new concept, it is possible to note vectors up to 100 km in RTK technique employment with the same high quality measurement. The equipment characteristics, distance limits and quality of the data recorded have been discussed and analyzed here in order to verify whether the results can achieve the necessary precision and accuracy.
PIERALICE, FEDERICA. "GNSS-based passive radar techniques for maritime surveillance." Doctoral thesis, 2019. http://hdl.handle.net/11573/1242385.
Повний текст джерелаLee, Yu-Chuan, and 李又權. "Application of M-estimation Techniques for Anti-Spoofing GNSS Navigation." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/knf5nx.
Повний текст джерела國立臺灣海洋大學
通訊與導航工程學系
104
The global navigation satellite system (GNSS) has been widely used by militaries as well as civilians. The use of GPS in mission-critical applications demands not only precise navigation solutions but solutions which can be used with absolute confidence. Spoofing is a deliberate interference that aims to coerce global navigation satellite system receivers into generating false position/navigation solutions. The GPS system is generally lack of immunity against spoofing attack. As such, spoofing and anti-spoofing algorithms have become an important research topic within the GPS discipline. Currently, Spoofing mitigation technique of anti-spoofing is mainly on positioning solution. This thesis to solve the problems of spoofing signal of robust estimation, using MEKF and MUKF, which are EKF (Extended Kalman Filter) and UKF (Unscented Kalman Filter) combined with M-estimation. And joining the detection mechanism, so that using optimal estimate when did not suffer spoofing signal; on the other hand, if suffer spoofing signal starting M-estimator and using robust estimate to solve position/navigation solutions. MEKF and MUKF can not only solve the nonlinear problems but also against spoofing signal, which have greatly improved the robust of estimation, and positional accuracy.
"Bayesian signal processing techniques for GNSS receivers: from multipath mitigation to positioning." Universitat Politècnica de Catalunya, 2009. http://www.tesisenxarxa.net/TDX-0202110-123003/.
Повний текст джерела"Sea state determnation using GNSS-R techniques: contributions to the pau instrument." Universitat Politècnica de Catalunya, 2009. http://www.tesisenxarxa.net/TDX-0529109-095953/.
Повний текст джерелаMenzione, Francesco. "New on-board multipurpose architecture integrating modern estimation techniques for generalized GNSS based autonomous orbit navigation." Tesi di dottorato, 2017. http://www.fedoa.unina.it/12093/1/Multipurpose_Earth_Orbit_Navigation_System_final_corr_4.pdf.
Повний текст джерелаAlsaif, Muhanned. "New Algorithms to Solve the Positioning Problem of Outdoor Localization Using Constrained and Unconstrained Optimization Techniques." Thesis, 2021. http://hdl.handle.net/10754/670250.
Повний текст джерелаChandrasekhar, J. "Performance Analysis Of Post Detection Integration Techniques In The Presence Of Model Uncertainties." Thesis, 2011. http://etd.iisc.ernet.in/handle/2005/2106.
Повний текст джерелаFeng, Szu-Chun, and 馮思鈞. "Analysis of Multipath Effect in GNSS Positioning Using Multicorrelator Technique." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/59882059205446762533.
Повний текст джерела國立成功大學
電機工程學系碩博士班
93
The thesis is concerned with the use of multicorrelator technique in reducing multipath effect in GNSS application. Although GNSS has been widely used in navigation and survey, its performance is subject to several errors such as ionosphere delay, troposphere delay and multipath. Among which, the multipath effect constitutes one of the most unpredictable error sources. The multicorrelator techniques is analyzed in the thesis to assess its effectiveness in multipath mitigation. Both BPSK and BOC modulations are considered.
Yen-HuaYeh and 葉燕樺. "Analyzing the Performance of Tightly Coupled INS/GNSS via post-processed Virtual Reference Station technique." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/93302645116989583265.
Повний текст джерела國立成功大學
測量及空間資訊學系碩博士班
101
Recently the useage of mobile mapping platform have been raised gradually in Taiwan. Currently mobile mapping technologies always apply INS/GNSS integrated system to get exterior orientation of image by Direct Georeferencing (DG). But the accuracy of DG is affected significantly by the accuracy of INS/GNSS integrated system because the error propagation from INS/GNSS integrated system to DG is linear. So the primary objective to increase the accuracy of mobile mapping system is to enhance the accuracy of INS/GNSS integrated system. This research investigates the impact different kinematic satellite positioning method on the positioning and orientation accuracy of an INS/GNSS integrated system. It uses raw measurements of INS/GNSS integrated system to perform three satellite positioning processes, including Differential GNSS (DGNSS), Precise Point Positioning (PPP) and post-processed Virtual Reference Station (VRS). The result shows the accuracy of using VRS in INS/GNSS integrated system satellite positioning is superior compared to other methods. Now the development of Network RTK (Network Real Time Kinematic, NRTK) in Taiwan is gradually becomimg mature. National Land Surveying and Mapping Center established e-GPS based on VRS and the provate company also set up a similar system known as Civil NET. Using post-processed VRS to do satellite positioning can save the cost of manpower which is needed in traditional DGNSS and still remain the accuracy which is needed in mobile mapping system.
(6114419), Tian Zhou. "ALTERNATIVE METHODOLOGIES FOR BORESIGHT CALIBRATION OF GNSS/INS-ASSISTED PUSH-BROOM HYPERSPECTRAL SCANNERS ON UAV PLATFORMS." Thesis, 2019.
Знайти повний текст джерелаLow-cost unmanned aerial vehicles (UAVs) utilizing push-broom hyperspectral scanners are poised to become a popular alternative to conventional remote sensing platforms such as manned aircraft and satellites. In order to employ this emerging technology in fields such as high-throughput phenotyping and precision agriculture, direct georeferencing of hyperspectral data using onboard integrated global navigation satellite systems (GNSS) and inertial navigation systems (INS) is required. Directly deriving the scanner position and orientation requires the spatial and rotational relationship between the coordinate systems of the GNSS/INS unit and hyperspectral scanner to be evaluated. The spatial offset (lever arm) between the scanner and GNSS/INS unit can be measured manually. However, the angular relationship (boresight angles) between the scanner and GNSS/INS coordinate systems, which is more critical for accurate generation of georeferenced products, is difficult to establish. This research presents three alternative calibration approaches to estimate the boresight angles relating hyperspectral push-broom scanner and GNSS/INS coordinate systems. For reliable/practical estimation of the boresight angles, the thesis starts with establishing the optimal/minimal flight and control/tie point configuration through a bias impact analysis starting from the point positioning equation. Then, an approximate calibration procedure utilizing tie points in overlapping scenes is presented after making some assumptions about the flight trajectory and topography of covered terrain. Next, two rigorous approaches are introduced – one using Ground Control Points (GCPs) and one using tie points. The approximate/rigorous approaches are based on enforcing the collinearity and coplanarity of the light rays connecting the perspective centers of the imaging scanner, object point, and the respective image points. To evaluate the accuracy of the proposed approaches, estimated boresight angles are used for ortho-rectification of six hyperspectral UAV datasets acquired over an agricultural field. Qualitative and quantitative evaluations of the results have shown significant improvement in the derived orthophotos to a level equivalent to the Ground Sampling Distance (GSD) of the used scanner (namely, 3-5 cm when flying at 60 m).