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A Performance Analysis of Two Civilian GNSS Receivers in a GNSS Contested Laboratory EnvironmentPorter, Michael Howard 23 September 2019 (has links)
No description available.
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New Methods and Architectures for High Sensitivity Hybrid GNSS Receivers in Challenging Environments / Nouvelles méthodes et architectures pour les récepteurs GNSS de haute sensibilité hybrides pour les environnements contraintsAndrianarison, Maherizo 02 October 2018 (has links)
Les systèmes de navigation par satellites GNSS ne cessent d’évoluer et ils sont déjà utilisés dans de nombreuses applications. Avec la venue des nouveaux systèmes Galileo et BeiDou ainsi que la modernisation des systèmes GPS et GLONASS, de nouveaux satellites ainsi que de nombreuses nouvelles fréquences et de nouveaux signaux feront leur apparition dans les prochaines années et qui vont encore ouvrir la porte à d’innombrables nouvelles applications. L’évolution rapide de la téléphonie mobile nécessite une meilleure exploitation des systèmes de navigation et de positionnement dans les environnements urbains.Jusqu'à maintenant, les signaux de navigation GPS ne peuvent pas être bien captés dans les environnements urbains. Les niveaux des signaux y sont très faibles et il est presque impossible d’acquérir et de poursuivre les signaux de façon autonome à cause de l'importance des obstacles. De plus, le positionnement à l’intérieur et dans les environnements urbains sont aussi soumis aux problèmes de multi-trajets, de masquage, d’interférences et de brouillages. Dans ces conditions, il faut pouvoir traiter des signaux très dégradés ou très courts qui ne permettent pas au récepteur d’effectuer le processus de poursuite. Ainsi, cela nous conduit à la nécessité de repenser l'architecture du récepteur GNSS pour les applications modernes.Ce projet de thèse consiste à développer de nouvelles méthodes et architectures de récepteur GNSS de haute sensibilité et robuste aux dégradations des signaux tout en concevant de nouveaux algorithmes intégrés dans un récepteur GNSS hybride capable de fonctionner dans les environnements urbains profonds ou « intérieurs ».La méthodologie prévoit l’utilisation de la nouvelle approche de « détection collective (CD) » ou « acquisition collaborative ». L'approche collaborative qui traite tous les signaux multi-satellites ouvre une solution intéressante. De nombreuses techniques existent dans la littérature pour résoudre les problèmes de positionnement dans les environnements urbains, mais nous proposons la nouvelle approche de détection collective en raison de sa performance en tant que méthode de positionnement direct et méthode d'acquisition de haute sensibilité, par l'application de la détection vectorielle de tous les satellites visibles. En effet, la bonne combinaison des valeurs de corrélation de plusieurs satellites peut réduire le niveau de C/N0 requis des signaux satellites par les algorithmes standards de traitement (acquisition et poursuite) qui ne peuvent pas être acquis individuellement mais permettent de contribuer de manière constructive à une solution collective de positionnement pour chaque utilisateur. L’objectif est de détecter collaborativement les satellites. La combinaison de différents signaux GNSS peut considérablement augmenter la sensibilité d'acquisition du récepteur. Malgré les avantages de cette approche, elle présente également des inconvénients tels que la charge de calcul élevée en raison du grand nombre de points candidats dans le domaine position/biais d’horloge. Ainsi, le travail proposé dans cette thèse consiste à réduire la complexité du CD en optimisant la recherche de points candidats dans le domaine position/biais d’horloge. Enfin, l'objectif est d'appliquer l'approche de détection collective au positionnement GNSS coopératif pour la navigation moderne dans des environnements difficiles. Pour cela, des algorithmes d'exploitation optimale des ressources du récepteur en sélectionnant les meilleurs satellites ou la station de référence seront développés selon certains critères tels que le niveau du rapport signal sur bruit (C/N_0), l’angle d’élévation des satellites ainsi que la configuration géométrique des satellites visibles. L’objectif final est de proposer une nouvelle architecture de récepteur cognitif de haute sensibilité permettant de recevoir de façon optimale les nouveaux signaux GNSS. / GNSS satellite navigation systems are constantly evolving and have been already used in many applications. With the advent of the new systems Galileo and BeiDou as well as the modernization of GPS and GLONASS systems, new satellites and numerous new frequencies and signals will appear in the coming years and will open door to countless new applications that are currently impossible. The rapid evolution of mobile telephony and personal navigation devices (PND) requires better use of navigation systems in non-ideal environments, especially the need for positioning in deep urban area. On the one hand, users are waiting for a high positioning accuracy, because of the proximity to various points of interest. On the other hand, urban environment brings specific difficulties in receiving GNSS signals.GNSS navigation signals cannot be properly captured in urban and "indoor" environments. Signal levels are very low and it is almost impossible to acquire and track signals autonomously because of the strong attenuation of signals due to obstacles. In addition, indoor and urban positioning are also subject to multipath problems, masking, interference and jamming. Under these conditions, we must be able to process highly degraded or very short signals that do not allow the receiver to go through the tracking process. Thus, this leads us to the need to rethink the architecture of GNSS receiver for modern applications.This thesis project consists of developing new GNSS methods and architectures of high sensitivity and robustness to signal degradations and designing new algorithms integrated into a hybrid GNSS receiver capable of operating in deep urban environments.The methodology involves the use of the new concept of “Collective Detection (CD)”, also called “collaborative acquisition”. The collaborative approach that treats multi-satellite signals all together opens an interesting solution. Many techniques exist in the literature to solve the problems of positioning in urban environments, but we propose the new Collective Detection approach because of its performance as both a Direct Positioning method, providing a coarse position/clock-bias solution directly from acquisition, and High-Sensitivity acquisition method, by application of vector detection of all satellites in view. Indeed, the correct combination of the correlation values of several satellites can reduce the required Carrier-to-Noise Ratio (C/N_0) level of the satellite signals which cannot be acquired individually by standard signal processing (acquisition and tracking) but make it possible to use them constructively to a positioning solution. The combination of different GNSS signals can considerably increase the acquisition sensitivity of the receiver. Despite the advantages of this approach, it also has drawbacks such as the high computational burden because of the large number of candidate points in the position/clock-bias domain. Thus, the work proposed in this thesis consists of reducing the complexity of the CD by optimizing the search for candidate points in position/clock-bias domain. Finally, the goal is to apply the CD approach to Cooperative GNSS Positioning for modern navigation in harsh environments. For that, algorithms for optimally exploiting receiver resources by selecting the best satellites or the reference station will be developed according to certain criteria such as the C/N_0 level, the elevation angle, and the geometric configuration of the visible satellites. The ultimate goal is to propose a design of a new smart receiver “High Sensitivity Cognitive GNSS Receiver (HS-CGR)” to optimally receive and process GNSS signals.
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Precisão de coordenadas planimétricas obtidas com receptores GNSS de pontos situados sob redes elétricas de alta tensão / Planimetric coordinate accuracy obtained with GNSS receivers located in points under high voltage electrical linesHillebrand, Fernando Luis 17 September 2012 (has links)
The purpose of this work was investigate and measure the possibility to exist
multipath caused by the corona noise generated in high voltage electric lines
recepting GNSS signals. Experiments were realized with a 69 kV tension electric line
localized in Santa Maria/RS. A serie was located with eleven transversal points to the
longitudinal ranging of the transmission line. In this points, the eletromagnetic field
was estimated using an equipment to measure the electromagnetic field EM-8000
model. Valuations was realized about the interferences on positioning by the absolut
method, using a GNSS receiver with C/A code Garmin GPS II Plus model and the
positioning by the relative method with the GNSS receiver L1/L2 Topcon Hiper
model. To estimate the interference in the points was necessary to obtain the
geodesic coordinates of this points without multipath possibilities caused of corona
noise. For this was implanted a squared topographical polygonal where the support
points were located far from the transmission lines, free of the electromagnetic field
influence. Calculating the variances among the coordinates was necessary transform
the geodesic coordinates obtained at GNSS receivers to the Local Topographic
System, to make the systems compatible, using the rotation and translation model.
Calculating was possible conclude that to the raising method and the geodesic
equipment used in this experiment, in a 69 kV transmission line, the found
discrepancies were in the standard deviation of 17,10 mm admitted to equipment
GNSS receiver L1/L2 and 15 mm to GNSS receiver C/A code, in a 95% confidence
level. So it was not evidenced interferences in the electromagnetic field at GNSS
signal reception. / O propósito deste trabalho foi investigar e mensurar a possibilidade de haver
multicaminhamento pelo efeito corona gerado em linhas elétricas de alta tensão na
recepção de sinais GNSS. Foram realizados experimentos em uma rede elétrica
com tensão de 69 kV localizado no município de Santa Maria/RS. Foi implantada
uma série de onze pontos transversais ao alinhamento longitudinal da linha de
transmissão. Nestes pontos realizou-se uma avaliação do campo eletromagnético
gerado utilizando um equipamento medidor de campo eletromagnético modelo EM-
8000. Foram realizadas avaliações da interferência no posicionamento pelo método
absoluto utilizando o receptor GNSS de código C/A Garmin modelo GPS II Plus e o
posicionamento pelo método relativo com o receptor GNSS portadora L1/L2 Topcon
modelo Hiper. Para avaliar a interferência dos pontos foi necessário obter as
coordenadas geodésicas desses pontos sem possibilidades de multicaminhamento
pelo efeito corona. Para isto implantou-se uma poligonal topográfica enquadrada em
que os marcos de apoio localizavam-se distantes a linha de transmissão sem a
influência do campo eletromagnético. Ao realizar o cálculo das discrepâncias entre
as coordenadas foi necessário realizar a transformação das coordenadas
geodésicas obtidas pelos receptores GNSS para o Sistema Topográfico Local para a
compatibilização dos sistemas, sendo utilizado o modelo das rotações e translações.
Realizando os cálculos concluiu-se que para os métodos de levantamento e os
equipamentos geodésicos utilizados neste experimento, em uma linha de
transmissão de 69 kV, as discrepâncias constatadas ficaram dentro do desviospadrões
de 17,10 mm admitido ao equipamento receptor GNSS portadora L1/L2 e
15 m ao receptor GNSS código C/A, a nível de confiança de 95%. Assim não se
constatou interferências do campo eletromagnético na recepção dos sinais GNSS.
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