Detta projekt undersöker vilken mätavvikelse man kan få av punktmoln från Unmanned Aircraft System (UAS)-insamlade bilder i jämförelse med terrester laserskanning. Skillnaden i noggrannhet mellan manuell identifiering och automatisk identifiering av markstödpunkter undersöks också. Arbetet undersöker även vad som krävs för att framställa 3D-modeller lämpliga för 3D-utskrift utifrån UAS-fotogrammetri. Projektet är en förstudie för dokumentation av Hälsingegårdar. UAS är en teknik som har blivit mer och mer populär under senaste år då det har blivit tillgänglig för allmänheten efter att tidigare enbart har används för militärt bruk. UAS består av en mindre flygfarkost, en sensor, ett tröghetsnavigationssystem (Inertial Navigation System, INS), en Global Positioning System (GPS)-mottagare, en radiolänk och en styrdator. 3D-modeller skapade från UAS insamling kan i sin tur användas för deformationsundersökningar, ombyggnadsprojekt eller friforms-framställning, även kallat 3D-utskrift. Studieområdet för detta projekt består av en byggnad vid Högskolan i Gävle. UAS som användes var en AscTec Falcon 8 oktokoper utrustad med Global Navigation Satellite System (GNSS) och en digitalkamera. Två flygningar utfördes, första flygningen tog lodbilder från höjden 75 m, andra flygningen tog snedbilder i höjdintervallet 10-15 m. Bilderna processades i programmet Agisoft PhotoScan inför skapande av ett tätt punktmoln. Jämförelsen mellan automatisk och manuell identifiering av markstödpunkter gjordes i PhotoScan med två olika sorters markstödpunkter, kodade A4 papper och traditionella 40 x 40 cm pappskivor. Byggnaden skannades också in med en LeicaScanStation C10 och punktmolnen fördes samman till ett gemensamt punktmoln i programmet Leica Cyclone. Punktmolnen, från UAS-bilderna och från laserskanningen, jämnfördes i form av stickprov i programmet CloudCompare. Fyra digitala 3D-modeller skapades, två utifrån sned- och lodbildernas punktmoln och två utifrån en kobination av lodbildernas och laserskanningens punktmoln. Första modellen skapades i PhotoScan som en Modelling Enviroment for Software and Hardware (MESH). Andra modellen var även den en MESH skapad i CloudCompare. Tredje modellen skapades av en kombination av lodbildernas och laserskanningens punktmoln i Cyclone genom att använda polyface-MESH. Fjärde modellen skapades i AutoCAD som solida objekt genom att använda modellen från Cyclone som referens. Utifrån stickproven i CloudCompare kan det konstateras att matta ytor med mörka färger eller ytor som ligger i skugga, avviker mer i avstånd från laserskanningspunktmolnet. Vid automatisk identifiering av kodade markstödpunkter från PhotoScan kunde programmet inte hitta några punkter automatiskt. Programmet hade inga problem med att hitta de traditionella 40 x 40 cm markstödpunkterna vid en automatisk identifiering. Utifrån resultaten från beräkningen av mätosäkerhet för 40 x 40 cm markstödpunkterna kan det konstateras att automatisk identifiering är noggrannare än manuell, vilket också har påståtts i manualen för PhotoScan. Däremot är skillnaden obetydlig och vid val av metod kommer automatisk identifiering vara fördelaktigt tidsmässigt. För att få en modell så skalenlig och detaljrik som möjlig så är det att föredra att använda en kombination av laserskanning och punktmoln från lodbilder, tills tekniken för att utvinna punkmoln från snedbilder har utvecklats mer.

京都大学 / 新制・課程博士 / 博士(情報学) / 甲第24745号 / 情博第833号 / 新制||情||139(附属図書館) / 京都大学大学院情報学研究科通信情報システム専攻 / (主査)教授 山本 衛, 教授 橋口 浩之, 教授 梅野 健 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

Ionospheric scintillations can cause significant amplitude and/or phase fluctuations of GNSS signals. This work presents analysis results of scintillation effects on the new GPS L5 signal based on data collected using a real-time scintillation monitoring and data collection system at HAARP, Alaska. The data collection setup includes a custom narrow band front end that collects GPS L1, L2 IF samples and two reconfigurable USRP2 based RF front ends to collect wideband GPS L5 and GLONASS L1 and L2 signals. The results confirm that scintillation has a stronger impact on GPS L2 and L5 signals than on the L1 signal. Our preliminary results also show that carrier phase and amplitude scintillations on each signal are highly correlated. The amplitude and carrier phase scintillation are also correlated among the three signals. In this study, a multi-constellation multi-band GNSS software receiver has been developed based on USRP2, a general purpose radio platform. The C++ class-based software receiver were developed to process the IF data for GPS L1, L2C, and L5 and GLONASS L1 and L2 signals collected by the USRP2 front end. The front end performance is evaluated against the outputs of a high end custom front end driven by the same local oscillator and two commercial receivers, all using the same real signal sources. These results demonstrate that the USRP2 is a suitable front end for applications, such as ionosphere scintillation studies. Another major contribution of this work is the implementation of a Vector tracking loop (VTL) for robust carrier tracking. The VTL is developed based on the extended Kalman filter (EKF) with adaptive covariance matrices. Both scalar tracking loop (STL) and VTL are implemented. Once an error in the scalar loop is detected, the results from the VTL are used to assist the STL. The performance of the VTL is compared with the traditional STL with three different data sets: raw GPS RF data with short signal outages, RF data with strong scintillation impacts collected during the last solar maximum, and high dynamic data with long interval signal outages from a GPS simulator. The results confirm the performance improvement of the VTL over scintillation impacts and show that the VTL can maintain signal lock during long intervals of signal outage if the satellite ephemerides are available and the pseudorange estimation is within one code chip accuracy. The dynamic performance improvement of the VTL is verified as well. The results show the potential of robust tracking based on VTL during scintillation and interference. / Ph. D.

En fungerande geodetisk infrastruktur är viktig för att kunna säkerhetsställa att geodetisk mätning går att genomföra om GNSS-tekniken skulle påverkas av störningar. Ludvika kommun saknar för närvarande kunskap om kvaliteten på kommunens nuvarande stomnät. Ludvika kommuns mätavdelning vill därför etablera ett nytt stomnät med hjälp av statisk GNSS-mätning. Syftet med detta arbete är att undersöka vilken lägesosäkerhet i plan och höjd som kan uppnås i ett stomnät etablerat med statisk GNSS-mätning inför planerad utveckling av ett nytt stomnät i Ludvika kommun.  Frågeställningar specificerades utifrån syftet med studien till: Vilken lägesosäkerhet får ett stomnät i plan och höjd vid användning av statisk GNSS-mätning vid etablering? Hur påverkas lägesosäkerheten i nätet av baslinjelängden till närmsta Swepos-station. Bildas det inom nätet olika lägesosäkerhetszoner när avståndet till närmsta Swepos-station varierar inom stomnätet med 5–15 km? Kan tillägg av korrektionsdata från en Swepos-station på 16 km avstånd påverka noggrannheten i stompunkter belägna på 15 km avstånd från närmsta Swepos- station?    Inom studien etablerades ett stomnät med 15 stompunkter runt orterna/områdena Blötberget, Gonäs, Klenshyttan, Skeppmora, Laggarudden, Hammarbacken och Lyviken i Ludvika kommun. Av punkterna var åtta gamla höjdfixar och resterande sju punkter var gamla polygonpunkter. Vid statisk GNSS-mätning på utvalda punkter anpassades sessionstid efter längsta baslinjelängd inom en session.    Stomnätet som etablerades i studien med statisk GNSS-mätning hade en genomsnittlig radiell lägesosäkerhet i plan på 0,011m och en genomsnittlig lägesosäkerhet i höjd på 0,015m. Det sågs i etablerat nät trender på att lägesosäkerhetszoner skapades, det var dock inom studien svårt att fastställa om det var sessionstid, baslinjelängd eller en annan faktor som var den bakomliggande faktorn. Tillägg av en Swepos-station innebar i sin tur en förbättring i lägesosäkerhet för de punkter som kopplades via baslinjer till den tillagda Swepos-stationen.

O constante avanço do Global Navigation Satellite System (GNSS) possibilita aos seus usuários ao redor do mundo a utilização de seus produtos para os mais diversos fins. Dentre eles, a navegação veicular autônoma se caracteriza como um dos principais focos de investimentos e pesquisas em universidades e instituições privadas. Concomitantemente, a modernização dos receptores GNSS acompanha esta evolução, oferecendo equipamentos de dimensões menores e mais versáteis que antes, com a capacidade de rastreio de novas constelações e operações de precisão em tempo real. O uso de redes de celulares e conexões de internet sem fio vêm apoiando este desenvolvimento, permitindo aos profissionais da área de geomática realizar levantamentos utilizando a técnica conhecida como Real Time Kinematic (RTK). Esta pesquisa tem por finalidade avaliar a qualidade de dados coletados por meio desta técnica RTK, apoiada no uso do Networked Transport of RTCM via Internet Protocol (Ntrip) para obtenção das correções diferenciais necessárias à operação, em ambiente urbano, e utilizando a Rede Brasileira de Monitoramento Contínuo dos Sistemas GNSS em tempo real (RBMC-IP). Para isto, foram feitas coletas de dados com um receptor de dupla frequência acoplado a um veículo, o qual percorreu o mesmo trajeto por vinte e nove dias. O local de realização dos testes foi o Corredor Norte-Sul da cidade de São Paulo, com extensão aproximada de 22.700 m. A metodologia de análise dos dados foi dividida em três casos: O primeiro considerou todo o trajeto. O segundo, apenas um trecho sem interferências (como árvores de grande porte, túneis, viadutos e prédios), plano e sem curvas. Por fim, o terceiro investigou como seria o comportamento do receptor após uma situação de bloqueio total do sinal de satélites, ao passar por baixo de um viaduto. Avaliou-se as precisões horizontais e verticais dos pontos registrados, a quantidade de satélites rastreados, os valores de Positional Dilution of Precision (PDOP), as soluções para o vetor das ambiguidades durante o percurso e a qualidade da conexão móvel. Os resultados mostraram que o uso da técnica RTK via Ntrip por meio de serviço RBMC-IP constitui-se uma ferramenta confiável para o posicionamento preciso em tempo real. Entretanto, em ambientes urbanos, e somado ao modo cinemático de coleta, tais valores tornam-se mais suscetíveis à degradação da precisão. / The continuous progress of the Global Navigation Satellite System (GNSS) enables its large user community around the world to use its products for a wide range of purposes. Amongst them, autonomous vehicular navigation is featured as one of the main focuses of investments and research in universities and private institutions. At the same time, the modernization of GNSS receivers follows this evolution, offering smaller and more versatile equipment than before, which are able to trace new constellations and high-precision operations in real time. The use of mobile networks and wireless Internet connections have supported this development, allowing geomatics professionals to carry out surveys using the technique known as Real Time Kinematic (RTK). This research aims at assessing the quality of the data gathered by this RTK technique, based on the use of the Networked Transport of RTCM via Internet Protocol (Ntrip) to obtain differential corrections necessary to the operation in an urban environment, and the use of Brazilian Network of Continuous Monitoring of GNSS Systems in real time (RBMC-IP). In order to do so, we gathered data with the receiver installed in a vehicle which travelled the same route for twenty-nine days. The test site was the North-South Corridor in São Paulo, which is approximately 22,700 m long. The methodology of data analysis was divided into three cases: The first one took the whole route into account. The second one, only one travel leg without interference (such as tall trees, tunnels, viaducts and skyscrapers), flat and curveless. Lastly, the third one investigated how the receiver would behave after a situation of total blockade of satellites, such as under a viaduct. We evaluated the horizontal and vertical accuracies of the recorded points, the number of satellites traced, the Positional Dilution of Precision (PDOP) values, the solutions to the vector of ambiguities during the course and the quality of the mobile connection. The results showed that the use of the RTK technique via Ntrip via the RBMC-IP service is a reliable tool for precise positioning in real time. However, in urban environments in addition to the kinematic mode of collection, such values become more susceptible to the degradation of precision.

Veículos autônomos são objeto de crescente estudo em todo o mundo. Face à Engenharia de Transportes, é tema que deve provocar uma revolução nas próximas décadas, pois é concreta a tendência ao uso destes veículos na sociedade. Podem se citar como grandes beneficiados a segurança, a logística, o fluxo de trânsito, o meio ambiente e também os portadores de deficiências. Com o objetivo de fazer um veículo atingir um ponto com coordenadas conhecidas de forma autônoma, uma plataforma veicular terrestre em escala foi utilizada, a qual recebeu um sistema computacional micro controlado e tecnologias para proporcionar mobilidade através de motores elétricos para tração e servo-motores para direcionamento; posicionamento por satélite através de receptor GNSS e bússola eletrônica para orientação; sensoriamento por ultra-som para evitar colisões; e comunicação sem fio, a fim de se realizar remotamente monitoramento e instrução em tempo real através de um aplicativo para computador pessoal (PC). Foi desenvolvido um algoritmo de navegação que, fazendo uso dos recursos disponíveis, proporcionou autonomia ao veículo, de forma a navegar para pontos com coordenadas conhecidas sem controle humano. Os testes realizados visaram avaliar a capacidade de autonomia do veículo, a trajetória de navegação realizada e a acurácia de chegada aos pontos de destino. O veículo foi capaz de atingir os pontos em todos os testes realizados, sendo considerado funcional seu algoritmo de navegação e também os sistemas de mobilidade, posicionamento, sensoriamento e comunicação. / Autonomous vehicles are an on growing research target around the world. Face to Transports Engineering, it is a subject which is expected to make a revolution on the next decades. The great benefits are on security, logistic, traffic flow, environment and handicap. With the goal to make a vehicle navigate autonomously to known geodesics coordinates, a reduced scale terrestrial vehicular platform was used. This platform received a microcontrolled computational system and technologies to give it mobility, through electrical motors for traction and servo-motors for direction; satellite positioning, through a GNSS receiver and magnetic compass for orientation; ultrasound sensing in order to avoid collision; and wireless communication, in order to do remote monitoring and instruction at real time through a PC application. It was developed a navigation algorithm which, from the available resources, gave autonomy to the vehicle, in order to navigate to known geodesics coordinates without human control. The test set was intended to evaluate the autonomy capacity of the vehicle, the navigation trajectory that was done and the arrival accuracy to the destination points. The vehicle reached the destination points on all tests done, being evaluated as functional its navigation algorithm and also the mobility, positioning, sensing and communication systems.

O constante avanço do Global Navigation Satellite System (GNSS) possibilita aos seus usuários ao redor do mundo a utilização de seus produtos para os mais diversos fins. Dentre eles, a navegação veicular autônoma se caracteriza como um dos principais focos de investimentos e pesquisas em universidades e instituições privadas. Concomitantemente, a modernização dos receptores GNSS acompanha esta evolução, oferecendo equipamentos de dimensões menores e mais versáteis que antes, com a capacidade de rastreio de novas constelações e operações de precisão em tempo real. O uso de redes de celulares e conexões de internet sem fio vêm apoiando este desenvolvimento, permitindo aos profissionais da área de geomática realizar levantamentos utilizando a técnica conhecida como Real Time Kinematic (RTK). Esta pesquisa tem por finalidade avaliar a qualidade de dados coletados por meio desta técnica RTK, apoiada no uso do Networked Transport of RTCM via Internet Protocol (Ntrip) para obtenção das correções diferenciais necessárias à operação, em ambiente urbano, e utilizando a Rede Brasileira de Monitoramento Contínuo dos Sistemas GNSS em tempo real (RBMC-IP). Para isto, foram feitas coletas de dados com um receptor de dupla frequência acoplado a um veículo, o qual percorreu o mesmo trajeto por vinte e nove dias. O local de realização dos testes foi o Corredor Norte-Sul da cidade de São Paulo, com extensão aproximada de 22.700 m. A metodologia de análise dos dados foi dividida em três casos: O primeiro considerou todo o trajeto. O segundo, apenas um trecho sem interferências (como árvores de grande porte, túneis, viadutos e prédios), plano e sem curvas. Por fim, o terceiro investigou como seria o comportamento do receptor após uma situação de bloqueio total do sinal de satélites, ao passar por baixo de um viaduto. Avaliou-se as precisões horizontais e verticais dos pontos registrados, a quantidade de satélites rastreados, os valores de Positional Dilution of Precision (PDOP), as soluções para o vetor das ambiguidades durante o percurso e a qualidade da conexão móvel. Os resultados mostraram que o uso da técnica RTK via Ntrip por meio de serviço RBMC-IP constitui-se uma ferramenta confiável para o posicionamento preciso em tempo real. Entretanto, em ambientes urbanos, e somado ao modo cinemático de coleta, tais valores tornam-se mais suscetíveis à degradação da precisão. / The continuous progress of the Global Navigation Satellite System (GNSS) enables its large user community around the world to use its products for a wide range of purposes. Amongst them, autonomous vehicular navigation is featured as one of the main focuses of investments and research in universities and private institutions. At the same time, the modernization of GNSS receivers follows this evolution, offering smaller and more versatile equipment than before, which are able to trace new constellations and high-precision operations in real time. The use of mobile networks and wireless Internet connections have supported this development, allowing geomatics professionals to carry out surveys using the technique known as Real Time Kinematic (RTK). This research aims at assessing the quality of the data gathered by this RTK technique, based on the use of the Networked Transport of RTCM via Internet Protocol (Ntrip) to obtain differential corrections necessary to the operation in an urban environment, and the use of Brazilian Network of Continuous Monitoring of GNSS Systems in real time (RBMC-IP). In order to do so, we gathered data with the receiver installed in a vehicle which travelled the same route for twenty-nine days. The test site was the North-South Corridor in São Paulo, which is approximately 22,700 m long. The methodology of data analysis was divided into three cases: The first one took the whole route into account. The second one, only one travel leg without interference (such as tall trees, tunnels, viaducts and skyscrapers), flat and curveless. Lastly, the third one investigated how the receiver would behave after a situation of total blockade of satellites, such as under a viaduct. We evaluated the horizontal and vertical accuracies of the recorded points, the number of satellites traced, the Positional Dilution of Precision (PDOP) values, the solutions to the vector of ambiguities during the course and the quality of the mobile connection. The results showed that the use of the RTK technique via Ntrip via the RBMC-IP service is a reliable tool for precise positioning in real time. However, in urban environments in addition to the kinematic mode of collection, such values become more susceptible to the degradation of precision.

La redistribution temporelle et spatiale des masses environnementales déforment la surface de la Terre. Ces déformations sont observables par des techniques de géodésie spatiale telles que le GNSS. Depuis que les produits d'orbite et d'horloge très précis de l'IGS sont disponibles, que des algorithmes sophistiqués ont été développés, l'iPPP a ouvert une nouvelle ère pour l'analyse du GNSS et pour son application dans les études géophysiques. Ce travail fait partie des premières études pour analyser les différents effets de surcharge, en utilisant des séries temporelles de positionnement, en particulier avec le logiciel GINS-PC et les nouveaux produits d'orbite et d'horloge REPRO2 du GRGS (GR2). Nous visons à exploiter les positions sub-diurnes d'iPPP pour étudier divers effets de déformation de la Terre à différentes échelles de temps: sub-diurne à saisonniers et annuels. Notre objectif est de contribuer à la validation des modèles géophysiques, à l'observation des différents phénomènes non-maréaux, mais aussi de présenter la performance du mode iPPP et du logiciel GINS-PC. Ce dernier est un outil puissant pour les applications géodynamiques, qui permet d'étudier l'influence des effets de surcharge sur l'interprétation géodésique des séries temporelles. Après un aperçu des principales déformations de la surface de la Terre, nous présentons les techniques de géodésie qui ont déjà démontré leur potentiel dans l'analyse de déformation, en particulier dans les études de déformation de surcharge. Nous présentons ensuite la technique de GNSS et le mode de traitement iPPP que nous utilisons pour l'analyse des données. Nous montrons ensuite les résultats de deux études régionales. La première analyse étudie l'influence des effets de surcharge sur la détermination des vitesses tectoniques dans la chaîne des Pyrénées à partir de campagnes GNSS espacées dans le temps. Le deuxième cas d'étude tente de suivre l'évolution spatiale et temporelle des déformations induites par un événement de tempête extrême, à savoir la tempête Xynthia qui a eu lieu en France en 2010. Cette étude tente également d'identifier la réponse dynamique de l'océan pour le système de basse pression atmosphérique se déplaçant rapidement en utilisant des séries temporelles sub-diurnes. Enfin, nous allons vers une étude globale qui pose les bases pour de futures recherches. / The temporal and spatial redistribution of the environmental masses deform the surface of the Earth. These deformations are observable by space geodetic techniques such as GNSS. Since highly accurate IGS satellite and clock data are available and sophisticated algorithms have been developped, the integer fixed ambiguity Precise Point Positioning (iPPP) method opened a new era for the Global Navigation Satellite System (GNSS) analysis and its application in geophysical studies. This work is among the first studies to investigate the different loading effects using iPPP time series, particularly using the GINS-PC software and the new, reprocessed REPRO2 orbit and clock products of GRGS (GR2). We aim to exploit the sub-daily iPPP time series to study various Earth deformation effects at different time scales, from sub-daily to seasonal and annual periods. Our goal is to contribute to the validation of geophysical models, to the observation of the various non-tidal phenomena, as well as the presentation of the performance of the iPPP mode and the GINS-PC package that is a powerful tool for geodynamical applications, and to investigate the influence of the loading effects on geodetic time series interpretation. After an overview of the main deformations of the Earth's surface, we present the geodetic techniques that already demonstrated their potential in deformation analysis, in particular in loading deformation studies. We then review the GNSS technique and the iPPP processing mode as it was our choice for the data analysis. We then demonstrate two regional studies. The first one investigates the influence of the loading effects on GNSS campaign to determine tectonic velocities in the Pyrenees mountain chain. The second case study attempts to track the spatial and temporal evolution of an extreme storm event, the Xynthia windstorm that occured in France, in 2010. This study also tries to identify the ocean's response to the fast moving low pressure system using sub-daily iPPP time series. Finally we go towards a global study which gives base for future research.

Les chaînes de réception de signaux satellitaires de navigation (GNSS), composées d'un récepteur, d'un câble d'antenne et d'une antenne, sont l'outil le plus utilisé lors de comparaisons d'horloges atomiques distantes nécessaires pour le calcul du Temps Atomique International (TAI). L'étalonnage de ces liens de temps, consistant à déterminer leur retard électrique lors de la propagation du signal au travers du système d'acquisition, est nécessaire afin de garantir leur exactitude et leur stabilité long-terme. Deux techniques d'étalonnage sont actuellement recensées : la méthode différentielle et la méthode en absolu. La technique différentielle consiste à comparer l'ensemble de la chaîne de réception à étalonner avec une chaîne de référence dont le retard est connu. Cette dernière circule de laboratoires en laboratoires afin que le BIPM (Bureau International des Poids et Mesures) puisse déterminer le délai interne des équipements opérationnels installés dans les laboratoires visités. La technique d'étalonnage dite en absolu consiste à déterminer indépendamment le retard électrique interne de chaque élément de la chaîne de réception en utilisant des signaux simulés permettant de s'affranchir des bruits liés à la diffusion de signaux satellitaires. Le CNES développe cette technique depuis 2005. Les travaux de cette thèse contribuent au développement et à l'optimisation des méthodes d'étalonnage en absolu de chacun des éléments de la chaîne de réception afin de déterminer le retard global de le la chaîne d'acquisition avec une incertitude inférieure à une nanoseconde. Cette méthode d'étalonnage permet également de caractériser les performances de chacun des composants du système d'acquisition ainsi que la sensibilité thermique et hygrométrique des récepteurs.

<p>Den svenska marinen likväl som världens handels sjöfart nyttjar alltmer satellitnavigering för sin positionering. Enligt totalförsvarets forskningsinstitut kan sådana system störas med förhållandevis enkla medel. Nu när den svenska marinen alltmer engagerar sig i insatser utomlands mot irreguljära motståndare väcks frågan om hur en irreguljär motståndare kan påverka den svenska marinen och den svenska marinens taktik. I denna uppsats kommer frågor kring en irreguljär motståndares förmåga att påverka GNSS att ställas. Samt frågan om vilken påverkan detta har för såväl den svenska marinens fartyg som handelssjöfarten. Uppsatsen kommer även att behandla möjligheterna till skydd mot störning samt hur den svenska marinens taktik kommer påverkas om en irreguljär motståndare försöker störa ut GNSS-system.</p> / <p>The Swedish Navy as well as the worlds shipping industries use more and more satellite navigation for positioning purposes. According to the Swedish Defence Research Agency, those types of systems can relatively easily and at a low cost be jammed. With the Swedish Navy becoming more and more involved in missions overseas against insurgents, the question is whether an insurgent can affect the Swedish Navy and its tactics. This paper investigates the questions about what opportunities an insurgent have to affect the GNSS-system and how that can affect the Swedish Navyas well as the shipping industries. This paper is also about how the tactics of the Swedish Navy will be affected if an insurgent attempts to jam the GNSS-systems and the possibility of protection against jamming.</p>