Satellites have revolutionized navigation by making it more universal, accessible and ac- curate. Global Positioning System (GPS) is the most widely used satellite navigation system in the world. However, it is prone to errors from various sources such as the ionosphere, troposphere and clock biases. In order to make the system very accurate and reliable, especially to meet the requirements of safety-critical applications, Satellite Based Augmentation Systems (SBAS) have recently been designed in various countries to augment the GPS by providing corrections for its errors. An Indian SBAS called GAGAN (GPS Aided Geo Augmented Navigation), developed for the Airports Authority of India (AAI) by Indian Space Research Organization (ISRO) is currently being installed and proven for aviation and other use. The uncertain propagation delay of signals through the ionosphere is the most important contributor of error in GPS positioning, its maximal elimination is a major task of SBAS overlays. Ionospheric delays have steady, cyclic, and irregular components. The last types are of particular concern because they are unpredictable. This thesis deals with ionospheric depletion, an important phenomenon of this class that is specific to tropical regions like India and hence have not been well studied in the context of other SBAS systems of the world which cover mid-latitude domains. Depletion is an ionospheric phenomenon in which the density of electrons dips suddenly and then returns close to the previous value. It poses a challenge to the model adopted for ionospheric delay estimation since it may not be detectable by ground systems be- cause of its localized nature, and its occurrence and intensity cannot be predicted. In this work we have analyzed the depletion characteristics over the Indian region such as its distribution, frequency of occurrence, and depth and duration parameters. We have then studied and implemented an existing algorithm to detect a depletion from the Total Electron Content (TEC) data. This algorithm has been found to be inaccurate for estimation of depletion duration, and we have proposed an improved algorithm for depletion detection and shown it to be more suitable for the Indian SBAS, GAGAN. The algorithm utilizes multiple thresholds for depletion detection in order to improve performance in the presence of irregularities including noise. These thresholds are determined by analyzing real TEC data containing depletion events over the Indian region. The detected depletion events are those that have a strong likelihood of contributing large range errors and degrading GAGAN's reliability. The thresholds include depletion parameters such as the depth, duration, rate of change of TEC, and the rate of change of slope of the TEC curve. The characterization of depletion events over the Indian region yielded useful insights into the behaviour of the phenomenon. It was observed that the depletion events were invariably present post-sunset, between 1900 and 0200 hrs. This observation is consistent with the other studies on plasma bubbles so far. The average depth of the depletion was found to be about 3.31 meters of propagation delay while the strongest depletion corresponds to about 5.04 meters of delay. The latter observation impresses upon the need to detect and study the phenomenon of depletion since it is capable of causing a significant loss of accuracy and reliability to the system. The duration of the depletion was found to range from about 10 min to 2.35 hours. In addition, a statistical study of the relationship among the different parameters and a study devoted to now-casting of depletion was made to get a more quantitative insight into the phenomenon of depletion. Scintillation is another phenomenon occurring in the ionosphere which causes rapid fluctuations of phase and amplitude of the signal due to TEC variations in the ionosphere. The occurrences of depletion were observed to be accompanied by scintillation, as also noted in previous studies. The correlation of depletion and scintillation was studied using the data available for this research. A spatial characterization of the depletion events was also investigated using the same temporal TEC data from neighbouring stations which were relatively close to each other. This study addressed the movement of the plasma bubble with respect to the advection speed and direction with definite results. Attention was also devoted to the spatial dimension of the bubble as observed from various stations. Contributions to this variability in the apparent spatial extent comes from the observation of the depletion event from varying lines-of-sight corresponding to different GPS satellites which are also moving, and the differential `slicing' effect because of the location of the stations with respect to the plasma bubble, in addition to the evolution of the bubble during transit. The detection of depletion and its temporal characterization, in addition to the knowledge of its spatial extent and motion, can provide very useful insights on the behaviour of a depletion event and over the ionosphere in general. This knowledge and the mechanism for detection can help to improve the quality and dependability of the information provided by SBAS systems, in particular the Indian GAGAN system, for improved navigation in this part of the world. The present thesis aims to make a significant contribution in this direction.

La navigation autonome des voitures robotisées est un domaine largement étudié avec plusieurs techniques et applications dans une démarche coopérative. Elle intègre du contrôle de bas niveau jusqu’à la navigation globale, en passant par la perception de l’environnement, localisation du robot, et autres aspects dans une approche référencée capteurs. Bien qu’il existe des travaux très avancés, ils présentent encore des problèmes et limitations liés aux capteurs utilisés et à l’environnement où la voiture est insérée.Ce travail aborde le problème de navigation des voitures robotisées en utilisant des capteurs à faible coût dans des milieux urbains. Dans cette thèse, nous avons traité le problème concernant le développement d’un système global de navigation autonome référencée capteur appliqué à un véhicule électrique intelligent, équipé avec des caméras et d’autres capteurs. La problématique traitée se décline en trois grands domaines de la navigation robotique : la perception de l’environnement, le contrôle de la navigation locale et la gestion de la navigation globale. Dans la perception de l’environnement, une approche de traitement d’image 2D et 3D a été proposé pour la segmentation de la route et des obstacles. Cette méthode est appliquée pour extraire aussi des caractéristiques visuelles, associées au milieu de la route, pour le contrôle de la navigation locale du véhicule. Avec les données perçues, une nouvelle méthode hybride de navigation référencée capteur et d’évitement d’obstacle a été appliquée pour le suivi de la route. Cette méthode est caractérisée par la validation d’une stratégie d’asservissement visuel (contrôleur délibératif) dans une nouvelle formulation de la méthode “fenêtre dynamique référencée image" (Dynamic Window Approach - DWA, en anglais) (contrôleur réactif). Pour assurer la navigation globale de la voiture, nous proposons l’association des données de cartes numériques afin de gérer la navigation locale dans les points critiques du chemin, comme les intersections de routes. Des essais dans les scénarios difficiles, avec une voiture expérimentale, et aussi en environnement simulé, montrent la viabilité de la méthode proposée. / Autonomous navigation of car-like robots is a large domain with several techniques and applications working in cooperation. It ranges from low-level control to global navigation, passing by environment perception, robot localization, and many others in asensor-based approach. Although there are very advanced works, they still presenting problems and limitations related to the environment where the car is inserted and the sensors used. This work addresses the navigation problem of car-like robots based on low cost sensors in urban environments. For this purpose, an intelligent electric vehicle was equipped with vision cameras and other sensors to be applied in three big areas of robot navigation : the Environment Perception, Local Navigation Control, and Global Navigation Management. In the environment perception, a 2D and 3D image processing approach was proposed to segment the road area and detect the obstacles. This segmentation approach also provides some image features to local navigation control.Based on the previous detected information, a hybrid control approach for vision based navigation with obstacle avoidance was applied to road lane following. It is composed by the validation of a Visual Servoing methodology (deliberative controller) in a new Image-based Dynamic Window Approach (reactive controller). To assure the car’s global navigation, we proposed the association of the data from digital maps in order tomanage the local navigation at critical points, like road intersections. Experiments in a challenging scenario with both simulated and real experimental car show the viabilityof the proposed methodology.

In this thesis, we analyze the performance of the Post Detection Integration (PDI) techniques used for detection of weak DS/CDMA signals in the presence of uncertainty in the frequency, noise variance and data bits. Such weak signal detection problems arise, for example, in the first step of code acquisition for applications such as the Global Navigation Satellite Systems (GNSS) based position localization. Typically, in such applications, a combination of coherent and post-coherent integration stages are used to improve the reliability of signal detection. We show that the feasibility of using fully coherent processing is limited due to the presence of unknown data-bits and/or frequency uncertainty. We analyze the performance of the two conventional PDI techniques, namely, the Non-coherent PDI (NC-PDI) and the Differential-PDI (D-PDI), in the presence of noise and data bit uncertainty, to establish their robustness for weak signal detection. We show that the NC-PDI technique is robust to uncertainty in the data bits, but a fundamental detection limit exists due to uncertainty in the noise variance. The D-PDI technique, on the other hand, is robust to uncertainty in the noise variance, but its performance degrades in the presence of unknown data bits. We also analyze the following different variants of the NC-PDI and D-PDI techniques: Quadratic NC-PDI technique, Non-quadratic NC-PDI, D-PDI with real component (D-PDI (Real)) and D-PDI with absolute component (D-PDI (Abs)). We show that the likelihood ratio based test statistic derived in the presence of data bits is non-robust in the presence of noise uncertainty. We propose two novel PDI techniques as a solution to the above mentioned shortcomings in the conventional PDI methods. The first is a cyclostationarity based sub-optimal PDI technique, that exploits the periodicity introduced due to the data bits. We establish the exact mathematical relationship between the D-PDI and cyclostationarity-based signal detection methods. The second method we propose is a modified PDI technique, which is robust against both noise and data bit uncertainties. We derive two variants of the modified technique, which are tailored for data and pilot channels, respectively. We characterize the performance of the conventional and proposed PDI techniques in terms of their false alarm and detection probabilities and compare them through the receiver operating characteristic (ROC) curves. We derive the sample complexity of the test-statistic in order to achieve a given performance in terms of detection and false alarm probabilities in the presence of model uncertainties. We validate the theoretical results and illustrate the improved performance that can be obtained using our proposed PDI protocols through Monte-Carlo simulations.

The purpose of this diploma thesis is testing motion of the device for GNSS antenna calibration according to added weight to the device’s transom. First part of this thesis is devoted to introduction into GNSS antenna calibration problematics. The thesis deals further with development of the software used to process photogrammetric images that have been taken during testing measurement. The rest of the thesis is focused to process and evaluate the measurement. The result will be implemented into observation model used during calibration measurement. The period, during the device is still, will be corrected according to the result that has been obtained from the measurement.

The master´s thesis deals with the application of unmanned aerial vehicle (UAV) in photogrammetry and mapping. The first part describes the UAV that was used for imaging, legislative restrictions resulting from its operations, planning and realization of the flight. The second part of this thesis is focused on processing results, especially on evaluation the accuracy of the results gained by UAV with and without a GNSS module. The data are evaluated in the 3rd accuracy rating class (ČSN 01 3410). The theoretical principles are explained as well. The main aim of the thesis is to demonstrate the effective use of the GNSS module Emlid Reach and the unmanned aerial vehicle in geodesy.

The main fokus of this D thesis consists in the creating of horizontal points in Lešná village that is closed to Valašské Meziříčí, part Vysoká. Sixty five points of horizontal control (PPBP) were located and set in Vysoká. The network adjustment was done with the help of the method of lest squares and coordinates were counted with the G-NET/Mini programme.

When we look at the eld of robotics we nd that exist a lot of types of robots. Some of tham use location navigation and global navigation for their work. This work aims to map options of location navigation and description of basic technique which used. Especially, we will deal with algorithms which work with optical sensors, for example camera, stereocamera or laser which scan medium. Practise section this work is focused on the proposal and implementacion algorithm which working with local navigation for robot's return to the starting position. All this work is connecting with tracked robot which formed in the framework one of project realization at Faculty of information technology.

The Aim of this master`s thesis was creation of a digital cadastral map in the part of cadastre unit Vilantice, in Chotěborky. There is an analog cadastral map scale 1:2 880 in the cadastre unit Vilantice currently. Review and completion of the positional point field was done by technology of global navigation satellite system and terrestrial methods. Result of this master`s thesis were the documentation of the review and completion of the positional point field, mapping sketches and vector file of a digital cadastral map.

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Trains are constrained to the railway tracks they operate on. This can be leveraged for absolute train positioning, where a train’s position can be mapped onto a digital track map (DTM). Extensive research has been dedicated to enhancing the accuracy of DTMs. However, certain practical applications necessitate compact DTMs that can be processed and transferred in real-time, thereby introducing a trade-off between accuracy and memory requirements. This study focuses on data reduction techniques for generating compact DTMs, presenting three distinct methods. Equidistantly sampled Cartesian coordinates are the input to all three methods as they employ different approaches: the linear method simplifies the polygonal chain that connects the coordinates, the spline method utilises smoothing B-splines for interpolation, and the geometric method interpolates the coordinates with a cubic spline and analyse the curvature to identify track segments and describe them geometrically. The performance of these methods is evaluated by their compactness in terms of the number of data fields needed, accuracy in representing track length, and the perpendicular distances between the ground truth track and the generated DTM. The compact DTM generation techniques are applied to three evaluation tracks specifically generated for this study, as well as two existing tracks in the Swedish railway network, each with distinct complexities and characteristics. On the evaluation tracks, the geometrical DTM excels when accuracy is prioritised. As greater perpendicular deviations are tolerated, the smoothed spline DTM method outperforms the other techniques in terms of compactness. The linear DTM method is superior when even greater perpendicular deviations are tolerated. On the existing tracks, the linear DTM method is outperforming the other methods in both accuracy and compactness, presumably because of limitations with the used data set. In conclusion, the choice of technique for generating compact DTMs depends on multiple factors, including the characteristics of the track and the desired level of accuracy. / Tåg är bundna till de järnvägsspår de trafikerar. Detta innebär att tågets digitala position kan förfinas genom att knyta tågets sensorinformation till en position på en digital spårkarta. Tidigare forskning har fokuserat på att förbättra precisionen i digitala spårkartor. Eftersom en del praktiska användningsområden av digitala spårkartor kräver att kartan är kompakt för att kunna bearbetas och överföras i realtid, uppstår en avvägning mellan precision och minneskrav. Denna studie fokuserar således på olika tekniker för datareduktion som kan användas för att generera kompakta spårkartor. Tre metoder tillämpas som alla använder samplade koordinater längs med järnvägsspåret som indata. Den linjära metoden förenklar det polygontåg som förbinder koordinaterna. I spline-metoden används utjämnande splines för att interpolera koordinaterna. Den geometriska metoden interpolerar koordinaterna med en kubisk spline och använder kurvaturen i splinen för att identifiera spårsegment och beskriva dessa geometriskt. De tre metoderna utvärderas och jämförs utifrån en analys avseende kompakthet, avvikelse från järnvägsspårets egentliga längd samt genom att mäta de vinkelräta avstånden mellan det riktiga spåret och spåret i den digitala spårkartan. Tre tågspår har skapats syntetiskt för att utvärdera de tre metoderna. Dessutom har två tågsträckor längs med Kinnekullebanan och Södra stambanan valts ut. Analysen visade att den geometriska spårkartan var mest kompakt på de syntetiska tågspåren när precision prioriterades högst. När kraven på precision minskades var spline-kartan mest kompakt på de syntetiska spåren. Däremot var den linjära metoden mest kompakt när kompakthet prioriterades över precision. Den linjära metoden var dominant med avseende på både precision och kompakthet på Kinnekullebanan och Södra stambanan, troligtvis på grund av begränsningar med den data över järnvägen som använts. Slutsatsen från denna studie är att valet av teknik för att generera kompakta spårkartor beror på flera faktorer, inklusive järnvägsspårets egenskaper och krav på precision.