Suchergebnisse

Global Positioning System (GPS) has been widely used worldwide for a variety of applications such as air, land and sea. The GPS and the Russian GLONASS are the only fully operational Global Navigation Satellite System (GNSS). Due to its several advantages, such as simplicity of use, successful implementation and global availability, this has been considered as the cornerstone of positioning in navigation system applications for the people who are visually impaired. However, due to standalone single frequency service, the positioning performance has not been sufficient for some accuracy and precision demanding applications. The problems of obtaining high accuracy real time positions in the field have led the navigation community to develop a GNSS augmentation system. However, several questions have been raised with this new development, such as how good the new method is? During any satellite configuration, would it be able to provide the accuracy at the same level? In a reliable way, would it be able to replace conventional GPS method? In this paper, a detailed review of all necessary understandings concerning GNSS and with a focal point on the GPS, GLONASS, Galileo, Beidou and GNSS augmentation systems positioning performance, is provided. The enormous demand to further improve positioning, navigation, and timing capabilities for both civil and military users on existing GNSS systems has directed efforts to modernise the GPS and GLONASS system and introduce new systems such as Galileo navigation system.

In den vergangenen Jahren wurden zwei Globale Navigations-Satelliten-Systeme (GNSS) aufgebaut, das amerikanische NAVigation System with Time And Ranging - Global Positioning System (NAVSTAR GPS) kurz GPS und das russischen Pendant, das GLObale Navigation Satellite Systems GLONASS. Beide erlauben einer unbegrenzten Anzahl von Nutzern eine hochgenaue Bestimmung ihrer Position in drei Koordinaten und der Zeit und dies weltweit und unter allen Witterungsbedingungen. Die ursprünglich ausschließlich für militärische Zwecke konzipierten Systeme stehen inzwischen auch zivilen Nutzern zur Verfügung. Es war vor allem die Nachfrage aus dem zivilen, vor allem aus dem Freizeitbereich die GPS Empfänger zu einem Massenprodukt werden ließ, mit kleinen Baugrößen und niedrigen Preisen. Derzeit nimmt vor allem die Zahl der kommerziellen Anwendungen z.B. in allen Bereichen des Verkehrswesens stark zu, aber auch im wissenschaftlichen Bereich und für hoheitliche Aufgaben im Vermessungswesen usw. wird GPS eingesetzt. Trotz der ständig steigenden Zahl privater und kommerzieller Nutzer liegt die Verfügungsgewalt ausschließlich bei den jeweiligen Militärs der beiden Großmächte. Da auch die technischen Eigenschaften des Systems nur auf militärische Anforderungen ausgerichtet sind, gibt es starke Bestrebungen zum Aufbau eines vom Militär unabhängigen Systems. Auf die Überlegungen und Pläne für ein derartiges ziviles Globales Navigations-Satelliten-System (GNSS), daß den Zur Verbesserung der Genauigkeit der Positionsbestimmung wird das sog. Differential GPS (DGPS) eingesetzt. Dabei nutzt man die Tatsache, daß die meisten Fehlereinflüsse für zwei nicht weit voneinander entfernte GPS-Empfänger die gleichen Abweichungen bei der Positionsbestimmung verursachen. Kennt man nun den Standort eines Empfängers, so kann man mit Hilfe der Differenz, die sich aus der Positionsmessung und dem tatsächlichen, bekannten Standort für diesen Referenzempfänger ergibt, die Messung des zweiten Empfängers mit unbekanntem Standort korrigieren. In vielen Ländern gibt es bereits derartige Referenzstationen und weiter befinden sich im Aufbau, so auch in Deutschland. Auf die Pläne zum Aufbau dieser DGPS-Stationen in Deutschland wird ausführlich eingegangen. ; To improve positioning accuracy principles of differential GPS (DGPS) are ap#

Civil Liability for Damage Caused by Global Navigation Satellite System' aims to explore whether current international law is adequate to deal with the issue of civil liability in the context of Global Navigation Satellite System (GNSS). It has come to pass that national security, economic growth, and transportation safety ? not to mention such infrastructure as banking and electricity ? are severely dependent on the positioning information, navigation capabilities, and time dissemination provided by GNSS. However, GNSS is not risk-free. The more humanity depends on GNSS, the more risks it has to face. It is irresponsible to wait for an accident to happen merely to justify the need for an appropriate GNSS civil liability regime. This book examines the structure of such a regime in unprecedented depth and proposes a uniform governance structure composed of an institutional framework and a legal system for GNSS, with safety-of-life signals at its core

Abstract. The impact of assimilating GNSS-ZTD (global navigation satellite system–zenith total delay) on the precipitable water vapor and precipitation forecast over Italy is studied for the month of October 2019, which was characterized by several moderate to intense precipitation events, especially over northwestern Italy. The WRF (Weather Research and Forecasting) model, version 4.1.3, is used with its 3D-Var data assimilation system to assimilate ZTD observations from 388 GNSS receivers distributed over the country. The dataset was built collecting data from all the major national and regional GNSS permanent networks, achieving dense coverage over the whole area. The water vapor forecast is verified for the forecast hours of 1–6 h after the last data assimilation time. Results show that WRF underestimates the atmospheric water vapor content for the period, and GNSS-ZTD data assimilation improves this underestimation. The precipitation forecast is verified in the phases of 0–3 and 3–6 h after the last data assimilation time using more than 3000 rain gauges spread over Italy. The application of GNSS-ZTD data assimilation to a case study improved the precipitation forecast by increasing the rainfall maximum and by better focusing the precipitation pattern over northeastern Italy, with the main drawback being the prediction of false alarms. Considering the study over the whole period, GNSS-ZTD data assimilation had a positive impact on rainfall forecast, with an improvement in the performance up to 6 h and with statistically significant results for moderate to intense rainfall thresholds (25–30 mm (3 h)−1).

The goal of this work is to review the current state of Global Navigation Satellite System (GNSS) development and its potential impact on the social, economic, and political dynamics of the various states fielding the systems. The most recognizable GNSS is the US GPS. It is the only operational system functioning at the time of this writing and has become part of the global commons. GPS, by virtue of its uniqueness, is considered the 'gold standard' of satellite based positioning, navigation, and timing systems. This uniqueness has also enabled the US to fully capitalize on the sizable economic dividends gained by the US technology sector from the development and sales of GPS user equipment and services. This work argues that the emergence of three global peer competitors to GPS is going to usher in a changed international relations environment for those new players. The economic implications go beyond a simple return on investment and could represent the continued space science and technical competitiveness of these states or not. The international political ramifications of the success or failure of the particular GNSSs could have a greater impact on the current international order than has been previously considered. The European Union, Russia, and China have become inexorably locked in a contest of domestic political will to field the next generation of GNSS in order to free themselves from US GPS domination and at the same time gain economic advantage over the other in space system technologies. Concurrently, the US is endeavoring to field the next generation of GPS and maintain its dominance in the associated technologies linked to GPS.

Global Navigation Satellite System (GNSS) receivers are the cornerstone of several modern systems: from smartphones to military applications. Therefore, their security is of utmost importance. This Master Thesis performs a security assessment on Septentrio's AsteRx-m3 receiver on two planes: a penetration testing engagement with the receiver's interfaces, and a GPS L1 C/A signal spoofing project. The assessment is satisfactory and distinct vulnerabilities are found on the web interface of the receiver, raging from low to high severity. On the GPS signal side, the Software Defined Radio used to carry out the spoofing is the HackRF One and the false GPS L1 C/A signal is generated using the software GPS-SDR-SIM. At first, the receiver detects the HackRF One signal Code-Carrier Divergence and repudiates the signal. After identifying and describing the problem, a fix is correctly implemented and, finally, the AsteRx-m3 receiver is successfully spoofed.

Chapter 1. Safety in navigation -- Chapter 2. Navigation bridge equipment -- Chapter 3. Automatic Identification System (AIS) -- Chapter 4. Route planning -- Chapter 5. Anti-collision and collision avoidance -- Chapter 6. Global Navigation Satellite System (GNSS) -- Chapter 7. Aviation.

In this paper, the potentials of using Global Navigation Satellite System (GNSS) techniques in the complex calibration procedure of the tracking sensors for missile test range applications have been presented. The frequently used tracking sensors in test range applications are- electro-optical tracking stations (EOTS) and tracking radars. Over the years, the EOTS are used as the reference for bias estimation of the radars. With the introduction of GPS in test range applications, especially the DGPS, the reference for bias estimation got shifted to DGPS from the EOTS. However, the achievable position solution accuracy is limited to the order of a few meters for DGPS, EOTS, and Radars. With the evolution of Multi-constellation GNSS and carrier-phase based measurement techniques in satellite navigation, achievable position solution accuracies may be improved to sub-meter level. New navigation techniques like real time kinematic (RTK) and precise point positioning have the potentials for use in the calibration procedures of the missile test ranges to the accuracies of centimeter-level. Moreover, because of the availability of a large number of navigation signals over the Indian region, multi-constellation GNSS receivers can enhance signal availability, reliability, and accuracies during the calibration of missile test ranges. Currently available compact, low-cost GNSS modules also offer the possibilities of using these for cost-effective, networked RTK for dynamic calibration of test ranges reducing cost and resource requirements.

The GNSS world is quickly growing. The United States' GPS, the European Union's Galileo, China's Compass, and Russia's GLONASS systems are all developing or modernizing their signals, and there will soon be more navigation satellites in space than ever before. The goal of this research was to develop an initial capability for an AFIT GNSS software receiver. This software receiver is intended to be used for research purposes at the Advanced Navigation Technology (ANT) Center. First a GPS-only software receiver was built. It successfully acquired, tracked, and provided reasonable position estimates. Next, the receiver was successfully modified to acquire and track a Compass satellite. This only required relatively small changes in the receiver software. During the tracking process, an interesting finding was discovered concerning the secondary code structure. There are in fact two secondary codes that the transmitter alternates. After AFIT's software receiver was configured properly, the signal was successfully tracked. Finally, the receiver was modified to track one of Galileo's satellites, GIOVE-A. After correct parametric changes were made, successful acquisition and tracking of the GIOVE-A signal was accomplished. AFIT's GNSS software receiver was shown to provide a high degree of flexibility and accuracy in acquiring and tracking GNSS signals.