Dans le domaine de l’Aviation Civile, les motivations de recherches sont souvent guidées par la volonté d’améliorer la capacité de l’espace aérien grâce à la modernisation des moyens de navigation aérienne existants et aux nouvelles infrastructures. Ces buts peuvent être atteints en développant les services qui permettent des opérations d’approche et d’atterrissage plus robustes et plus fiables. La navigation par satellite, grâce au Global Navigation Satellite System (GNSS), a été reconnue comme un moyen performant de fournir des services de navigation aérienne [1] [2]. Le concept du GNSS requiert l’utilisation de moyen d’augmentations pour fournir une fonction de contrôle d’intégrité au vu des exigences [1] relatives aux applications critiques de type aviation civile. Un de ces moyen est le GBAS (Ground Based Augmentation System) et est standardisé par l’OACI pour fournir un service de navigation incluant les approches de précision allant jusqu’à la catégorie I incluse, en utilisant les constellations GPS ou GLONASS [3]. Des études sont en cours pour permettre d’étendre ce service jusqu’à la catégorie II/III avec le GPS L1 C/A, cependant des contraintes sont apparues lors de la surveillance de la ionosphère. Grâce à la modernisation du GPS et GLONASS et aux futures constellations Galileo et Beidou, les futurs GNSS utilisant de multiples constellations et de multiples fréquences (MC/MF) sont étudiés. Les activités de recherches européennes se sont appuyées sur la constellation GPS et sur la future constellation Galileo. Ce MC/MF GBAS devrait permettre de nombreuses améliorations comme un meilleur modèle des retards atmosphériques. Cependant, des challenges doivent être résolus avant d’atteindre les bénéfices potentiels. Dans ce travail de thèse, 2 principaux sujets en rapport avec le GBAS ont été traités, la transmission des données de corrections avec le MC/MF GBAS et l’impact des biais troposphériques avec le SC/SF et MC/MF GBAS. Dû aux contraintes portant sur le format des messages transmis à l’utilisateur via l’unité VDB [4], une nouvelle approche est nécessaire pour permettre l’élaboration du MC/MF GBAS. Une des solutions proposée dans cette thèse est de transmettre les corrections et les données d’intégrité à l’utilisateur dans des messages séparés à des fréquences différentes. De plus, ce travail de thèse remet en question la modélisation de l’atmosphère et particulièrement celle de la troposphère dans des conditions nominales que non-nominales en se concentrant d’abord sur le calcul du pire gradient troposphérique avant de développer les précédents travaux pour borner cette menace dans le but de protéger l’utilisateur. En vue du futur MC/MF GBAS, une nouvelle approche s’est avérée nécessaire. Ainsi, dans ce projet de thèse, des modèles météorologiques numériques (NWMs) sont utilisés pour estimer intégralement la composante horizontale du pire gradient troposphérique. Une méthode innovante pour rechercher les pires gradients troposphériques horizontaux est utilisée pour déterminer les biais qu’ils induisent impactant les avions visant une approche de Cat II/III avec le GBAS. Un modèle de ces pires biais de mesures troposphériques différentiels horizontaux dépendant de l’élévation des satellites pour 2 régions européennes est alors développé. La composante verticale est aussi modélisée grâce à une étude statistique qui compare les données réelles au modèle standard. Un modèle du biais différentiel total non corrigé est développé et doit être introduit dans le calcul des niveaux de protections sous des conditions nominales. Pour borner l’impact de la troposphère sur l’erreur de position tout en se focalisant sur le souhait d’avoir un nombre de données transmises à l’utilisateur faible, différentes solutions conservatives ont été développées où au minimum 3 paramètres, définis selon leur région géographique d’utilisation, doivent être transmis à l’utilisateur. / In the Civil Aviation domain, research activities aim to improve airspace capacity and efficiency whilst meeting stringent safety targets. These goals are met by improving performance of existing services whilst also expanding the services provided through the development of new Navigation Aids. One such developmental axe is the provision of safer, more reliable approach and landing operations in all weather conditions. The Global Navigation Satellite System (GNSS) has been identified as a key technology in providing navigation services to civil aviation users [1] [2] thanks to its global coverage and accuracy. The GNSS concept includes the provision of an integrity monitoring function by an augmentation system to the core constellations. This is needed to meet the required performances which cannot be met by the stand-alone constellations. One of the three augmentation systems developed within civil aviation is the GBAS (Ground Based Augmentation System) and is currently standardized by the ICAO to provide precision approach navigation services down to Cat I using the GPS or GLONASS constellations [3]. Studies on-going with the objective to extend the GBAS concept to support Cat II/III precision approach operations with GPS L1 C/A, however some difficulties have arisen regarding ionospheric monitoring. With the deployment of Galileo and Beidou alongside the modernization of GPS and GLONASS, it is envisaged that the GNSS future will be multi-constellation (MC) and multi-frequency (MF). European research activities have focused on the use of GPS and Galileo. The MC/MF GBAS concept should lead to many improvements such as a better modelling of atmospheric effects but several challenges must be resolved before the potential benefits may be realized. Indeed, this PhD has addressed two key topics relating to GBAS, the provision of corrections data within the MC/MF GBAS concept and the impact of tropospheric biases on both the SC/SF and MC/MF GBAS concepts. Due to the tight constraints on GBAS ground to air communications link, the VDB unit, a novel approach is needed. One of the proposals discussed in the PhD project for an updated GBAS VDB message structure is to separate message types for corrections with different transmission rates. Then, this PhD argues that atmospheric modelling with regards to the troposphere has been neglected in light of the ionospheric monitoring difficulties and must be revisited for both nominal and anomalous scenarios. The thesis focuses on how to compute the worst case differential tropospheric delay offline in order to characterize the threat model before extending previous work on bounding this threat in order to protect the airborne GBAS user. In the scope of MC/MF GBAS development, an alternative approach was needed. Therefore, in this PhD project, Numerical Weather Models (NWMs) are used to assess fully the worst case horizontal component of the troposphere. An innovative worst case horizontal tropospheric gradient search methodology is used to determine the induced ranging biases impacting aircraft performing Cat II/III precision approaches with GBAS. This provides as an output a worst case bias as a function of elevation for two European regions.The vertical component is also modelled by statistical analysis by comparing the truth data to the GBAS standardized model for vertical tropospheric correction up to the height of the aircraft. A model of the total uncorrected differential bias is generated which must be incorporated within the nominal GBAS protection levels. In order to bound the impact of the troposphere on the positioning error and by maintaining the goal of low data transmission, different solutions have been developed which remain conservative by assuming that ranging biases conspire in the worst possible way. Through these techniques, it has been shown that a minimum of 3 parameters may be used to characterize a region’s model.

Dans le domaine de l'aviation civile, afin de répondre à la demande croissante du trafic, les activités de recherche sont guidées par la volonté d’améliorer la capacité de l'espace aérien. Des recherches sont en cours dans tous les domaines de l'aviation civile: Communication, Navigation, Surveillance (CNS) et de gestion du trafic aérien (Air Traffic Management, ATM). En ce que concerne la navigation, les objectifs devraient être atteints par l'amélioration des performances des services existants grâce au développement des nouvelles aides à la navigation et la définition de nouvelles procédures basées sur ces nouveaux systèmes. La navigation par satellite, grâce au concept de Global Navigation Satellite System (GNSS), est reconnue comme une technologie clé pour fournir des services de navigation précis avec une couverture mondiale. Le concept GNSS a été défini par l'Organisation de l'Aviation Civile Internationale (OACI). Son importance dans l'aviation civile peut être observée dans l'avionique de nouveaux avions puisque la majorité d'entre eux sont maintenant équipés de récepteurs GNSS. Le GNSS comprend une fonction de surveillance de l'intégrité fournie par un système d’augmentation en plus de la constellation de base. Ceci est nécessaire pour répondre à toutes les exigences concernant la précision, l'intégrité, la continuité et la disponibilité qui ne peuvent pas être fournis par les constellations autonomes comme le GPS ou Glonass. Trois systèmes d’augmentation ont été développés au sein de l'aviation civile: le GBAS (Ground Based Augmentation System), le SBAS (Satellite Based Augmentation System) et l’ABAS (Aircraft Based Augmentation System). Le système GBAS, en particulier, est actuellement standardisé pour fournir des services de navigation, comme l'approche de précision, jusqu’à la Catégorie I (CAT I) en utilisant les constellations GPS ou Glonass et des signaux dans la bande L1. Ce service est connu sous le nom de GBAS Approach Service Type-C (GAST-C). Afin d'étendre ce concept jusqu'à des approche de précision CAT II/II, les activités de recherche sont en cours pour définir le nouveau service appelé GAST-D. Parmi tous les défis, la surveillance de la menace ionosphérique est le secteur où le niveau d'intégrité est insuffisant. Grâce au développement des nouvelles constellations, Galileo et Beidou, et grâce au processus de modernisation des autres constellations existantes, GPS et Glonass, l'avenir du GNSS sera Multi-Constellation (MC) et Multi-Fréquence (MF). En Europe, les activités de recherche se sont concentrées sur un système GNSS Bi-Constellation (Dual-Constellation, DC) basé sur GPS et Galileo. Afin de surmonter les problèmes rencontrés par en fonctionnement Mono-Fréquence (Single-Frequency, SF) en présence d’anomalies ionosphériques, l'utilisation de deux fréquences (Dual-Frequency, DF) a été sélectionnée comme un moyen d'améliorer la détection des anomalies ionosphériques et d'atténuer les erreurs résiduelles ionosphériques. Les avantages d'un système DC/DF GBAS (GAST-F) sont : •la robustesse de l'ensemble du système contre toute interférence involontaire grâce à l'utilisation de mesures effectuées dans deux bandes de fréquences protégées, •la robustesse contre une panne d’une des deux constellations,•l'amélioration de la précision à l'aide de nouveaux signaux avec des performances améliorées, et plusieurs satellites. Cependant, l'utilisation de nouveaux signaux et d’une nouvelle constellation, n’apporte pas que des avantages. Elle soulève également une série de défis qui doivent être résolus de profiter pleinement de ce nouveau concept. Dans cette thèse, certains défis, liés à un système DC/DF GBAS ont été étudiés. Un d’entre eux, causé par l'utilisation de nouveaux signaux GNSS, est de déterminer l'impact des sources d'erreur qui sont décorrélées entre la station au sol et l'avion et qui induisent une erreur sur la position estimée. De plus, avec l’utilisation de deux fréquences, il y a la pos / In Civil Aviation domain, to cope with the increasing traffic demand, research activities are pointed toward the optimization of the airspace capacity. Researches are thus ongoing on all Civil Aviation areas: Communication, Navigation, Surveillance (CNS) and Air Traffic Management (ATM). Focusing on the navigation aspect, the goals are expected to be met by improving performances of the existing services through the developments of new NAVigation AIDS (NAVAIDS) and the definition of new procedures based on these new systems. The Global Navigation Satellite System (GNSS) is recognized as a key technology in providing accurate navigation services with a worldwide coverage. The GNSS concept was defined by the International Civil Aviation Organization (ICAO). A symbol of its importance, in civil aviation, can be observed in the avionics of new civil aviation aircraft since a majority of them are now equipped with GNSS receivers. The GNSS concept includes the provision of an integrity monitoring function by an augmentation system in addition to the core constellations. This is needed to meet all the required performance metrics of accuracy, integrity, continuity and availability which cannot be met by the stand-alone constellations such as GPS. Three augmentation systems have been developed within civil aviation: the GBAS (Ground Based Augmentation System), the SBAS (Satellite Based Augmentation System) and the ABAS (Aircraft Based Augmentation System). GBAS, in particular, is currently standardized to provide precision approach navigation services down to Category I (CAT I) using GPS or Glonass constellations and L1 band signals. This service is known as GBAS Approach Service Type-C (GAST-C). In order to extend this concept down to CAT II/III service, research activities is ongoing to define the new service called a GAST-D. Among other challenges, the monitoring of the ionospheric threat is the area where the integrity requirement is not met. Thanks to the deployment of new constellations, Galileo and Beidou, and the modernization process of the existing ones, GPS and Glonass, the future of GNSS is envisaged to be Multi-Constellation (MC) and Multi-frequency (MF). In Europe, research activities have been focused on a Dual-Constellation (DC) GNSS and DC GBAS services based on GPS and Galileo constellations. Moreover, to overcome the problems experienced by Single-Frequency (SF) GBAS due to ionosphere anomalies, the use of two frequencies (Dual Frequency, DF) has been selected as a mean to improve ionosphere anomalies detection and to mitigate ionosphere residual errors. Advantages in using a DC/DF GBAS (GAST-F) system are, however, not only related to the integrity monitoring performance improvement. Benefits, brought by DC and DF, are also related to •the robustness of the entire system against unintentional interference thanks to the use of measurements in two protected frequency bands, •the robustness against a constellation failure, •the accuracy improvement by using new signals with improved performance, and more satellites. However, the use of new signals and a new constellation, does not bring only benefits. It also raises a series of challenges that have to be solved to fully benefit from the new concept. In this thesis, some challenges, related to DC/DF GBAS, have been investigated. One of them, rising from the use of new GNSS signals, is to determine the impact of error sources that are uncorrelated between the ground station and the aircraft and that induce an error on the estimated position. Using two frequencies, there is the possibility to form measurement combinations like Divergence-free (D-free) and Ionosphere-free (I-free) for which the errors impact has to be analyzed. In this thesis, the impact of the uncorrelated errors (noise and multipath as main sources) on ground measurements is analyzed. The aim is to compare the derived performances with the curve proposed in (RTCA,Inc DO-253C, 2008) for the

This master‘s thesis is focused on the evaluation of conditions for IFR operations in the Czech Republic and their neighbours. The thesis is also focused on evaluation of posibilities of IFR navigation for small airports. In this context part of thesis is dedicated to a modern way of navigation using GNSS.

The content of this work is description of current preccision approach system ILS. The location is Brno Tuřany airport. Meteorogic and traffic information was sorted to aim to show current conditions at the airport. In relation to these informations was made project of future GNSS approach in Brno Tuřany

The content of this work is an overview of precision approach used by GNSS and avionics for operation in low visibility conditions. This thesis describes existing requirements and proposals for new standards that are important to define GBAS performance. The objective of this work is to compare the alternative systems to guide aircraft during precision approach CAT II/III. GBAS operational implementation is additionally devised in this thesis.

Baigiamajame magistro darbe nagrinėjamos palydovinės tikslaus tūpimo pagal prietaisus sistemos taikymo Lietuvos aviacijoje galimybės. Aptartos palydovinės navigacijos sistemos tikslumą įtakojančios paklaidos, jų šaltiniai. Nagrinėjama GBAS sistemos struktūra, veikimo principas, paklaidų eliminavimo būdai. Išnagrinėtos šios sistemos panaudojimo galimybės (infrastruktūros ir ekonominiu požiūriais) tarptautiniuose Vilniaus, Kauno, Palangos ir Šiaulių oro uostuose. Atlikti bandymai Vilniaus tarptautiniame oro uoste, įvertinant potencialias GPS paklaidas bei įvertinant GBAS sistemos tikslumo ir tinkamumo galimybes. Išnagrinėjus teorinius ir praktinius tyrimo rezultatus, pateikiamos baigiamojo darbo išvados ir siūlymai. Darbą sudaro 9 dalys: įvadas, analitinė dalis, palydovinės radijo navigacinės sistemos antžeminė patikslinimo sis-tema, diferencinės pataisos, tikslaus artėjimo tūpti GBAS sistema, tiriamoji dalis, rezultatų apibendrinimas, literatūros sąrašas, priedai. Darbo apimtis – 63 p. teksto be priedų, 40 iliustr., 11 lent., 34 bibliografiniai šaltiniai. Atskirai pridedami darbo priedai. / This master’s thesis explores possibilities of satellite precision instrument landing application for Lithuanian avia-tion. At the first part of the thesis satellite navigation errors affecting its accuracy and their sources were examined. GBAS system stricture, its operation and error elimination methods were reviewed. Further explored were possibilities of imple-menting the analyzed system (infrastructure and economic terms) in international Vilnius, Kaunas, Palanga and Šiauliai airports. Test were carried out in Vilnius international airport aiming for assessment of potential GPS signal errors and estimation of GBAS systems accuracy and fitness opportunities, followed by theoretical and practical examination of the analysis data collected. Based on the examination results final thesis conclusions and recommendations are formulated and provided at the ending of this thesis. Structure: introduction, analytical part, ground based augmentation system, diferential corrections, precision lan-ding GBAS system, exploratory part, conclusions and suggestions, references. Thesis consist of: 63 p. text without appendixes, 40 pictures, 11 tables, 34 bibliographical entries. Appendixes included.

[pt] Esta tese apresenta um estudo dos efeitos ionosféricos em um Sistema de Aumento Baseado no Solo (GBAS) em regiões equatorial e de baixas latitudes. A ionosfera afeta a propagação dos sinais de GPS e pode reduzir a precisão do posicionamento nas regiões equatorial e de baixas latitudes. Sistemas auxiliares foram desenvolvidos para atender aos requisitos de segurança da aviação. Nesse contexto, o GBAS fornece maior precisão para correções diferenciais. Para avaliar o desempenho de um GBAS, um modelo de simulação do sinal-no-espaço GPS L1 foi desenvolvido, considerando o retardo ionosférico baseado nas distribuições estatísticas dos resíduos de Conteúdo Eletrônico Total vertical obtido do modelo IRI e estimativas da Rede Brasileira de Monitoramento Contínuo, em combinação com representação para a cintilação ionosférica de amplitude, simulada com base em distribuições de probabilidade (Alfa) - (Mi), bem como a cintilação de fase, gerada de acordo com as relações empíricas entre os índices (s)4 and (Sigma)(Fi). O modelo de sinal do GPS L1 também considera erros de relógios e aleatórios, retardos troposféricos, ambigüidade de ciclo e efeitos de multipercurso, para uma descrição completa. Os resultados de sinal-no-espaço são injetados em um modelo de simulação da instalação terrestre do GBAS, implementado para detectar uma variedade de possíveis anomalias ou falhas no sinal-no-espaço e para gerar correções diferenciais baseadas em algoritmos de monitoramento. O GBAS gera correções e seu desempenho é avaliado para aproximações de aeronaves em diferentes condições ionosféricas nos aeroportos do Rio de Janeiro e Fortaleza, enfatizando a Categoria de aproximação I. Os erros horizontais e verticais são estimados usando correções de GBAS para avaliar a precisão. A integridade do GBAS também é analisada calculando os níveis de proteção horizontal e vertical. / [en] This research presents a study on ionospheric effects on a Ground Based Augmentation System (GBAS) in equatorial and low latitude regions. The ionosphere affects the propagation of GPS signals and can reduce the positioning accuracy in the equatorial and low-latitude regions. Auxiliary systems have been developed to meet the safety requirements of aviation. In this context, GBAS provide higher accuracy for differential corrections. To evaluate the performance of a GBAS, a simulation model of the GPS L1 signal-in-space has been developed, considering ionospheric delay based on statistical distributions of vertical Total Electron Content residuals obtained from IRI model and Rede Brasileira de Monitoramento Contínuo estimates, in combination with amplitude ionospheric scintillation simulated based on (Alfa) - (Mi) probability distributions, as well as phase scintillation, generated according to empirical relationships between the indices (S)4 and (Sigma)(Fi). The GPS L1 signal model also considers clock and random errors, tropospheric delays, ambiguity, and multipath, for a complete description. The signal in space results are injected into a GBAS ground facility simulation model, implemented to detect a varied array of possible anomalies or failures in the signal in space and to generate differential corrections based on monitoring algorithms. The GBAS generates corrections and its performance is evaluated for aircraft approaches under different ionospheric conditions at the Rio de Janeiro and Fortaleza Airports, emphasizing Approach Category I. The horizontal and vertical errors are estimated using GBAS corrections to evaluate the accuracy. The GBAS integrity is also analyzed by computing the horizontal and vertical protection levels.

La navigation par satellite, Global Navigation Satellite System, a été reconnue comme une solution prometteuse afin de fournir des services de navigation aux utilisateurs de l'Aviation Civile. Ces dernières années, le GNSS est devenu l'un des moyens de navigation de référence, son principal avantage étant sa couverture mondiale. Cette tendance globale est visible à bord des avions civils puisqu'une majorité d'entre eux est désormais équipée de récepteurs GNSS. Cependant, les exigences de l'Aviation Civile sont suffisamment rigoureuses et contraignantes en termes de précision de continuité, de disponibilité et d'intégrité pour que les récepteurs GPS seuls ne puissent être utilisés comme unique moyen de navigation. Cette réalité a mené à la définition de plusieurs architectures visant à augmenter les constellations GNSS. Nous pouvons distinguer les SBAS (Satellite Based Augmentation Systems), les GBAS (Ground Based Augmentation Systems), et les ABAS (Aircraft Based Augmentation Systems). Cette thèse étudie le comportement de l'erreur de position en sortie d'architectures de récepteur qui ont été identifiées comme étant très prometteuses pour les applications liées à l'Aviation Civile. / Since many years, civil aviation has identified GNSS as an attractive mean to provide navigation services for every phase of flight due to its wide coverage area. However, to do so, GNSS has to meet relevant requirements in terms of accuracy, integrity, availability and continuity. To achieve this performance, augmentation systems have been developed to correct the GNSS signals and to monitor the quality of the received Signal-In-Space (SIS). We can distinguish GBAS (Ground Based Augmentation Systems), ABAS (Airborne Based Augmentation Systems) SBAS (Satellite Based Augmentation Systems). In this context, the aim of this study is to characterize and evaluate the GNSS position error of various positioning solutions which may fulfil applicable civil aviation requirements for GNSS approaches. In particular, this study focuses on two particular solutions which are: • Combined GPS/GALILEO receivers augmented by RAIM where RAIM is a type of ABAS augmentation. This solution is a candidate to provide a mean to conduct approaches with vertical guidance (APV I, APV II and LPV 200). • GPS L1 C/A receivers augmented by GBAS. This solution should allow to conduct precision approaches down to CAT II/III, thus providing an alternative to classical radio navigation solutions such as ILS. This study deals with the characterization of the statistics of the position error at the output of these GNSS receivers. It is organised as following. First a review of civil aviation requirements is presented. Then, the different GNSS signals structure and the associated signal processing selected are described. We only considered GPS and GALILEO constellations and concentrated on signals suitable for civil aviation receivers. The next section details the GNSS measurement models used to model the measurements made by civil aviation receivers using the previous GNSS signals. The following chapter presents the GPS/GALILEO and RAIM combination model developed as well as our conclusions on the statistics of the resulting position error. The last part depicts the GBAS NSE (Navigation System Error) model proposed in this report as well as the rationales for this model.

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No. of bitstreams: 1 pereira_vas_dr_prud.pdf: 34672414 bytes, checksum: f357f584172b46b5d27f842642bd82f7 (MD5) Previous issue date: 2018-09-13 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dentre os métodos de posicionamento GNSS (Global Navigation Satellite System) utilizados pela aviação no suporte das fases de aproximação e pouso preciso de aeronaves, destacam-se o SBAS (Satellite-Based Augmentation System) e o GBAS (Ground-Based Augmentation System). O GBAS tem a capacidade de corrigir a maioria dos erros envolvidos na pseudodistância a partir do DGNSS (Differential GNSS), desde que a camada ionosférica apresente um comportamento não perturbado na região do aeroporto. Entretanto, dependendo do fluxo de ionização solar, da atividade geomagnética, do ciclo de manchas solares, do ângulo zenital do Sol e da localização geográfica, a ionosfera pode sofrer fortes perturbações, proporcionando uma ameaça à integridade do GBAS, uma vez que podem ser diferentes os efeitos ionosféricos em pequenas distâncias. Assim, investigações dos erros sistemáticos devido à camada ionosférica no GBAS tem sido objeto de estudos há alguns anos. Nesse sentido, modelos de risco ionosférico, que visam determinar a máxima decorrelação ionosférica espacial existente entre a estação GBAS e a aeronave que se aproxima num aeroporto, foram desenvolvidos ou avaliados, principalmente para o hemisfério norte, mais precisamente para o território norte-americano, onde se destaca o CONUS (Conterminous United States) Threat Model. Nessa área o comportamento da ionosfera é mais estável em comparação com o observado sobre o Brasil, localizado na região ionosférica equatorial e de baixas latitudes, que apresenta a ocorrência da Anomalia de Ionização Equatorial (AIE), bolhas ionosféricas, irregularidades ionosféricas, cintilação ionosférica e Anomalia Magnética do Atlântico Sul (AMAS). A implantação de um GBAS no Brasil, por meio do Departamento de Controle do Espaço Aéreo (DECEA), despertou o interesse de seu uso com segurança. Sendo assim, a pesquisa propôs investigar a aplicabilidade do modelo CONUS de risco ionosférico para GBAS no território brasileiro, utilizando o método dos pares de estações (station-pair method), além de estimar os parâmetros para os principais aeroportos internacionais do Brasil, considerando a variação sazonal, bem como investigar os benefícios quanto ao uso dos sinais GLONASS (Global’naya Navigatsionnaya Sputnikovaya Sistema), Galileo e da portadora L5 do GPS (Global Positioning System) no modelo. Para isso, foram utilizados dados GNSS de várias redes ativas entre os anos de 2000 e 2016, bem como dados do GBAS instalado no aeroporto internacional do Rio de Janeiro/RJ (Galeão). Para a determinação dos parâmetros do modelo de risco e do parâmetro de integridade σvig (vertical ionospheric gradient sigma), esse último utilizado para estimar os níveis de proteção horizontal e vertical da aeronave, foi implementado um sistema denominado MoR_Ion. Os parâmetros do modelo CONUS estimados para o Brasil, utilizando sinais GPS para a combinação de portadoras L1/L2, mostraram que é inviável o uso de um GBAS considerando todo o território nacional. Uma alternativa foi estimativa local e temporal para os aeroportos de interesse. Valores obtidos indicaram que o GBAS pode, provavelmente, ser utilizado nos aeroportos internacionais de São Paulo/SP (Cumbica), Rio de Janeiro/RJ (Galeão), Brasília/DF (Presidente Juscelino Kubitschek) e Recife/PE (Gilberto Freyre) com algumas restrições quanto à estação do ano, hora do dia e elevação dos satélites. Já para o aeroporto internacional de Porto Alegre/RS (Salgado Filho) é o único, entre os analisados, em que nenhuma restrição à instalação do GBAS no local foi identificada a partir do conjunto de dados processados. Resultados empregando os sinais GPS e Galileo, para a combinação L1/L5, apresentaram ser melhores que os da combinação L1/L2. Já em relação ao GLONASS, verificou-se que há uma semelhança com os resultados do GPS. A determinação do σvig em tempo real para cada satélite disponível se apresentou como uma alternativa interessante, uma vez que transmite para a aeronave a real condição ionosférica no momento da aproximação e pouso, ao contrário da atual configuração do GBAS de transmitir um valor fixo de σvig que, teoricamente, contempla todas as possíveis perturbações ionosféricas. Estimativas de níveis de proteção para aproximação no Galeão indicaram que há a possibilidade de se realizar um procedimento CAT-I, utilizando satélites GPS ou GLONASS (combinação L1/L2), desde que sejam aplicadas restrições local-temporais previamente estabelecidas. Verificou-se, também, que a utilização dos satélites GLONASS em concomitância com o GPS possibilita a obtenção de valores que atendem aos limiares para um pouso CAT-III, uma vez que uma maior quantidade de satélites e, consequentemente, uma melhor configuração geométrica, é disponibilizada. Um estudo de caso utilizando o time-step method para a região do aeroporto de São José dos Campos/SP, onde se encontram cinco estações em um raio de 10 km, indicou que gradientes desse método podem ser empregados na estimativa dos valores dos parâmetros. Entretanto, tal método tem pouca semelhança com a arquitetura de uma estação GBAS e uma aeronave que se aproxima e, adicionalmente, não soluciona a decorrelação temporal. Por fim, um método alternativo que pode indicar a realização ou não do pouso consiste no monitoramento das irregularidades ionosféricas em tempo real na região circundante de um determinado aeroporto. Experimento realizado em tempo real, mas utilizando dados GPS e GLONASS de março de 2014 (próximo ao pico do ciclo solar 24), mostrou fortes irregularidades para a região do Galeão, com a frente ionosférica se deslocando de sudoeste a nordeste. Assim, uma medida que pode ser empregada para estimar os níveis de proteção consiste em não utilizar os sinais dos satélites que atravessam tais irregularidades. / Among the methods of GNSS (Global Navigation Satellite System) positioning used by the aviation in the support of the phases of approach and precise landing of aircraft, stand out the SBAS (Satellite-Based Augmentation System) and the GBAS (Ground-Based Augmentation System). GBAS has the ability to correct most of the errors involved in pseudorange from DGNSS (Differential GNSS), provided that the ionospheric layer exhibits undisturbed behavior in the airport region. However, depending on the flow of solar ionization, geomagnetic activity, sunspot cycle, zenith angle of the sun and geographic location, the ionosphere can suffer severe disturbances, posing a threat to the integrity of the GBAS, since the ionospheric effects may be different at small distances. Thus, investigations of systematic errors due to the ionospheric layer in GBAS have been the subject of studies for some years. In this sense, ionospheric threat models, which seek to determine the maximum existing spatial ionospheric decorrelation between the GBAS station and the aircraft approaching an airport, have been developed or evaluated, especially for the northern hemisphere, more precisely to the US territory, which highlights the CONUS (Conterminous United States) Threat Model. In this area, the ionosphere behavior is more stable compared to that observed in Brazil, located in the equatorial and low latitude ionospheric region, which presents the occurrence of Equatorial Ionization Anomaly (EIA), ionospheric bubbles, ionospheric irregularities, ionospheric scintillation and South Atlantic Magnetic Anomaly (SAMA). The implementation of a GBAS in Brazil, through the Department of Airspace Control (DECEA), aroused the interest of its use with safety. Therefore, the research proposed to investigate the applicability of the CONUS Threat Model to GBAS in the Brazilian territory, using the station-pair method, besides estimating the parameters for the main international airports of Brazil, considering the seasonal variation, as well as investigating the benefits of using the GLONASS (Global’naya Navigatsionnaya Sputnikovaya System), Galileo and GPS (Global Positioning System) L5 carrier in the model. For this purpose, GNSS data from several active networks were used between 2000 and 2016, as well as data from GBAS installed at Rio de Janeiro International Airport (Galeão). For the determination of the parameters of the threat model and the σvig (vertical ionospheric gradient sigma) integrity parameter, the latter used to estimate the aircraft horizontal and vertical protection levels, a system called MoR_Ion was implemented. The parameters of the CONUS model estimated for Brazil, using GPS signals for the combination of L1/L2 carriers, showed that it is impracticable to use a GBAS considering the entire national territory. An alternative was a local and temporal estimate for the airports of interest. The values obtained indicate that the GBAS can probably be used in the international airports of São Paulo/SP (Cumbica), Rio de Janeiro/RJ (Galeão), Brasília/DF (President Juscelino Kubitschek) and Recife/PE (Gilberto Freyre) with some restrictions on the season, time of day and satellite elevation. At the international airport of Porto Alegre/RS (Salgado Filho) it is the only one, among the analyzed ones, in which no restriction to the installation of the GBAS in the place was identified from the data set processed. Results using the GPS and Galileo signals for the L1/L5 combination were better than the L1/L2 combination. Regarding GLONASS, it was found that there is a similarity with the GPS results. The determination of the real time σvig for each available satellite was presented as an interesting alternative, since it transmits to the aircraft the actual ionospheric condition at the time of approach and landing, unlike the current GBAS configuration of transmitting a fixed value of σvig which theoretically covers all possible ionospheric disturbances. Estimates of protection levels for approach in Galeão indicated that there is the possibility of performing a CAT-I procedure, using GPS or GLONASS satellites (L1/L2 combination), provided that previously established local-temporal restrictions are applied. It was also verified that the use of GLONASS satellites in concomitance with GPS allows obtaining values that meet the thresholds for a CAT-III landing, since a larger number of satellites and, consequently, a better geometric configuration, is made available. A case study using the time-step method for the airport region of São José dos Campos/SP, where five stations are located within a 10 km radius, indicated that gradients of this method can be used to estimate the parameter values. However, this method has little resemblance to the architecture of a GBAS station and an aircraft approaching and additionally does not solve the temporal decorrelation. Finally, an alternative method that may indicate whether or not the landing is carried out is to monitor ionospheric irregularities in real time in the surrounding region of a given airport. A real-time experiment using GPS and GLONASS data from March 2014 (near the peak of the solar cycle 24) showed strong irregularities for the Galeão region, with the ionospheric front moving from southwest to northeast. Thus, one way that can be used to estimate protection levels is to not use satellite signals that cross such irregularities. / FAPESP: 2015/20522-7

Sammanfattning I varje flygfas av en kommersiell flygrutt krävs att navigations- och inflygningshjälpmedlen klarar högt ställda krav på noggrannhet, kontinuitet, tillgänglighet och integritet. Befintliga ILS-landningssystem klarar inte alla de kraven. GBAS, som är en modern teknik, kan däremot ppfylla uppställda krav med hjälp av GPS-satellitsignaler och ge stöd för alla faser av precisionsinflygningskategorier. GBAS-teknik kan ersätta ILS-tekniken och göra flygtrafiken säkrare under olika flygfaser. Systemet tillämpar konceptet "differentiella korrigeringar" för att förstärka GPS-satellitsignaler och överföra korrigeringar från GNSS-data till utrustade flygplan i närheten av en flygplats. Detta möjliggör att angränsade flygplatser kan förses med behövligt stöd och möjliggöra precisionsinflygningar upp till CAT III. Syftet med examensarbetet har varit att analysera GBAS-system och dess effekter på en flygplats och jämföra det med ILS-system för att bedöma vilket som är bäst. Sedan om möjligt ge förslag på hur man kan rädda små flygplatser med hjälp av GBAS-teknik. Arbetet inleddes med informationsinsamling om systemets tekniska och operativa kriterier. Utifrån denna information skapades ett analysschema för att analysera skillnaderna mellan landningssystemen. Resultaten av arbetet och analysschemat visar att GBAS-systemet bedöms vara mer ändamålsenligt med avseende på ekonomiska, tekniska och operativa förhållanden jämfört med ILS-systemet. Analyserna tyder också på att GBAS är ett bättre alternativ än ILS på små flygplatser och att man kan använda resultaten som verktyg för att identifiera olika problem med ILS-systemet. / Abstract Nowadays we have two general rules for flight: VFR (Visual Flight Rules) and IFR (Instrument Flight Rules). VFR can only be used according to visual flight rules, where the pilot always has visual contact with the ground. In low visibility conditions (such as fog, snow, low clouds level, rain and darkness) the pilot uses ILS (Instrument Landing System) to position the aircraft for approach and landing. Those situations at ILS are categorized into three different stages: CAT I, CAT II and CAT III. The categories are based on the sight (visibility conditions). ILS is sensitive to nearby radio signals from other devices and to buildings around the airport and cannot guide multiple aircraft simultaneously. At the same time the critical and sensitive areas of the ILS result in a reduction of the throughput under low-visibility conditions. In addition, the system is expensive and requires great maintenance. Another important disadvantage of this system is that it allows only straight approach (Not curved flying within landing and approach). Most of the airports’ landing systems have some inaccuracy and unreliability. It is due to older models and systems. Systems like ILS, VOR, TLS, MLS, GPS, GNSS, etc., have been constantly modernized and are used to reduce the risk of incidents and accidents during approach and landing phases which are crucial steps in the flight. However, the GPS (Global Position System) precision method cannot alone meet ICAO’s (International Civil Aviation Organization) requirements when additional accuracy, integrity, accessibility and continuity are required. In order to meet the ICAO requirements, one needs to strengthen the GNSS’s performance by using the GBAS system and guaranteeing very high performance in a given coverage area such as, an airport. The current GBAS has already been certified for CAT1 and can be improved to ICAO requirements. CAT II / III has already been developed by the ICAO Navigation System Panel (NSP) but not yet appended to Annex 10 as an alternative to ILS. Annex 10 is an ICAO regulation that contains all standards and practices for aviation telecommunications. This thesis study provides an overall overview of the aircraft’s performance with different aids and specifies new landing system and compares with some of the existing systems. Limitations are studied in order to analyze the best available new system that can be achieved.