Designing a Universal GNSS Simulator for Pseudorange Calculation

The development of GNSS (Global Navigation Satellite System) receivers, especially mass market receivers, has to face cost constraints. To reduce the time to market, and thus the costs, the usage of a GNSS signal simulation facility is one possibility. GNSS signal simulators provide an effective tool for simulating the behavior of satellite-based navigation systems. The challenge is that they have to be model the real world as close as possible, taking satellite orbits, atmospheric effects, satellite clock errors, multipath effects, etc. into account. Thus these simulators achieve lower hardware complexity and precise position determination even when proper signal from satellites is absent. The aim is to design a simulator which can simulate the satellite signals while keeping the all the errors as low as possible while keeping the G.D.O.P. in the range of 4 to 5. DOI: 10.17762/ijritcc2321-8169.15017

Radio Frequency Interference Impact Assessment on Global Navigation Satellite Systems

The Institute for the Protection and Security of the Citizen of the EC Joint Research Centre (IPSC-JRC) has been mandated to perform a study on the Radio Frequency (RF) threat against telecommunications and ICT control systems. This study is divided into two parts. The rst part concerns the assessment of high energy radio frequency (HERF) threats, where the focus is on the generation of electromagnetic pulses (EMP), the development of corresponding devices and the possible impact on ICT and power distribution systems. The second part of the study concerns radio frequency interference (RFI) with regard to global navigation satellite systems (GNSS). This document contributes to the second part and contains a detailed literature study disclosing the weaknesses of GNSS systems. Whereas the HERF analysis only concerns intentional interference issues, this study on GNSS also takes into account unintentional interference, enlarging the spectrum of plausible interference scenarios.JRC.DG.G.6-Security technology assessmen

A System-Level Engineering Approach for Preliminary Performance Analysis and Design of Global Navigation Satellite System Constellations

This paper presents a system-level engineering approach for the preliminary coverage performance analysis and the design of a generic Global Navigation Satellite System (GNSS) constellation. This analysis accounts for both the coverage requirements and the robustness to transient or catastrophic failures of the constellation. The European GNSS, Galileo, is used as reference case to prove the effectiveness of the proposed tool. This software suite, named GNSS Coverage Analysis Tool (G-CAT), requires as input the state vector of each satellite of the constellation and provides the performance of the GNSS constellation in terms of coverage. The tool offers an orbit propagator, an attitude propagator, an algorithm to identify the visibility region on the Earth's surface from each satellite, and a counter function to compute how many satellites are in view from given locations on the Earth's surface. Thanks to its low computational burden, the tool can be adopted to compute the optimal number of satellites per each orbital plane by verifying if the coverage and accuracy requirements are fulfilled under the assumption of uniform in-plane angular spacing between coplanar satellites.Comment: 19 pages, 21 figure

Improvement of vertical precision in GPS positioning with a GPS-over-fiber configuration and real-time relative hardware delay monitoring

Une des principales limitations du positionnement GPS est que la composante verticale est généralement 2 à 3 fois moins précise que la composante horizontale. Pour des applications de haute précision, il est possible d'atteindre, par méthode GPS en mode relatif, des précisions de l'ordre de quelques millimètres en composante horizontale mais non pas en composante verticale. Cependant, plusieurs applications, telles que l'auscultation de structures d'ingénierie, exigent une précision similaire tant en horizontal qu'en vertical. Par simulations, il a été démontré par (Santerre & Beutler, 1993), qu'il est possible d'améliorer la précision du positionnement vertical en utilisant un récepteur à antennes multiples et un calibrage précis du délai de propagation relatif dans les câbles et circuits électroniques séparant les antennes du récepteur. Cependant, aucune implementation n'avait été faite à ce jour pour prouver le concept. L'objectif principal de ce travail de recherche a donc été de concevoir et d'implémenter un tel système et de démontrer qu'il permet une nette amélioration dans la précision du positionnement vertical. Pour ce faire, le défi principal a été de développer un système permettant simultanément le transport des signaux GPS sur fibres optiques et le calibrage précis du délai de propagation relatif entre ces mêmes fibres en temps réel. Une fois le premier prototype complété et testé, des expériences réalisées sur une poutrelle de calibrage utilisée comme ligne de base de référence démontrent qu'avec le prototype et le système de traitement des données proposé, une nette amélioration dans la précision du positionnement vertical a été observée. Tel que prévu par la théorie et les simulations, une amélioration d'un facteur 2 à 3 a été atteint, permettant ainsi d'obtenir la même précision dans la composante verticale que dans la composante horizontale. Ces résultats, qui représentent une percée importante dans le positionnement GPS de haute précision, permettent ainsi d'envisager le déploiement de ce type de systèmes dans des applications réelles où la même précision dans toutes les composantes tridimensionnelles est essentielle mais n'avait pas pu être atteinte auparavant par positionnement relatif GPS

Vibration frequencies extraction of the Forth Road Bridge using high sampling GPS data

This paper proposes a scheme for vibration frequencies extraction of the Forth Road Bridge in Scotland from high sampling GPS data. The interaction between the dynamic response and the ambient loadings is carefully analysed. A bilinear Chebyshev high-pass filter is designed to isolate the quasistatic movements, the FFT algorithm and peak-picking approach are applied to extract the vibration frequencies, and a GPS data accumulation counter is suggested for real-time monitoring applications. To understand the change in the structural characteristics under different loadings, the deformation results from three different loading conditions are presented, that is, the ambient circulation loading, the strong wind under abrupt wind speed change, and the specific trial with two 40 t lorries passing the bridge. The results show that GPS not only can capture absolute 3D deflections reliably, but also can be used to extract the frequency response accurately. It is evident that the frequencies detected using the filtered deflection time series in different direction show quite different characteristics, and more stable results can be obtained from the height displacement time series. The frequency responses of 0.105 and 0.269Hz extracted from the lateral displacement time series correlate well with the data using height displacement time series

Air Force Institute of Technology Research Report 2006

This report summarizes the research activities of the Air Force Institute of Technology’s Graduate School of Engineering and Management. It describes research interests and faculty expertise; lists student theses/dissertations; identifies research sponsors and contributions; and outlines the procedures for contacting the school. Included in the report are: faculty publications, conference presentations, consultations, and funded research projects. Research was conducted in the areas of Aeronautical and Astronautical Engineering, Electrical Engineering and Electro-Optics, Computer Engineering and Computer Science, Systems and Engineering Management, Operational Sciences, Mathematics, Statistics and Engineering Physics

System Development for Geolocation in Harsh Environments

Wireless sensor networks (WSN) consist of a set of distributed devices equipped with multiple sensors, which can be employed in different environments of varying characteristics. Nowadays, node localization has become one of their most basic and important requirements. Due to the nature of certain environments, typical positioning systems, such as Global Navigation Satellite System (GNSS), cannot be employed. Therefore, in recent years several alternative positioning mechanisms have risen. ROMOVI is a project which has as its main goal the development of low cost autonomous robots capable of monitoring and perform logistic tasks on the steep slopes of the Douro river vineyards. Integrated in this project, this dissertation proposes the development of a full-custom wireless communication system for geolocation purposes in harsh environments. Using a Symmetric Double Sided Two Way Ranging (SDS-TWR) algorithm, it is possible to achieve ranging measures between nodes, thus providing accurate relative positioning. This work focuses mainly on the study of the SDS-TWR algorithm and its major error sources, such as those due to digital clock drift, among others. A preamble based on Frank-Zadoff-Chu sequence was developed and, due to its good periodic autocorrelation properties, a system employing the transmission and reception of this preamble was implemented in hardware, through a field programmable gate array (FPGA). By employing an embedded logic processor, the Altera Nios II, control over the complete procedure of the aforementioned algorithm is possible, to perform and analyze the main advantages of the SDS-TWR algorithm. Finally, a medium access control (MAC) layer frame format was defined, in order to enable future development of communication among multiple nodes, to enhance the original algorithm and, as such, provide the capability of trilateration

Radar Imaging in Challenging Scenarios from Smart and Flexible Platforms

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Design of double band Beidou navigation antenna with wide axial ratio beam

ObjectivesIn order to effectively broaden the beam width of the 3 dB axis ratio of a Beidou antenna, this paper proposes a slotted laminated microstrip patch antenna loaded with parasitic elements. MethodsThe Beidou dual frequency band feature is realized through a two-layer substrate structure. The bandwidth is widened by slotting. Circular polarized radiation is achieved by cutting corners at the edge of the patch. At the same time, L-shaped parasitic elements are loaded around the patch to broaden the 3 dB axial ratio beam width of the antenna.ResultsThe measured and simulated results are in good agreement. The relative bandwidths of the antenna in the Beidou B1 and B2 bands are 3% and 7.5%. The beam width of the 3 dB axis ratio can reach 180° and 176°, and the maximum gain can reach 6 dBi. In the Beidou receiver test, the number of antenna satellites can reach more than 17, and the positioning accuracy is within meters. ConclusionsThis paper proposes and validates a high-precision positioning dual band Beidou navigation antenna with wide axis ratio beam width. The results can provide references for the design of small Beidou navigation antennas