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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.

Dr. Madry, one of the world's leading experts in the field, provides in a condensed form a quick yet comprehensive overview of satellite navigation. This book concisely addresses the latest technology, the applications, the regulatory issues, and the strategic implications of satellite navigation systems. This assesses the strengths and weaknesses of satellite navigation networks and review of all the various national systems now being deployed and the motivation behind the proliferation of these systems.

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#

In the next 5 to 10 years, the world will experience the emergence of a true Global Navigation Satellite System (GNSS) - a compatible and, in many respects, interoperable system of systems. The U.S. Global Positioning System, Europe's Galileo, perhaps Russia's Glonass system, and regional augmentations including the Wide Area Augmentation System (WAAS), the European Geostationary Navigation Overlay Service (EGNOS), radiobeacon-based systems such as the U.S. Nationwide Differential GPS, and compatible commercial differential correction services will comprise this multifaceted GNSS. Common signal structures and frequency plans will enable combined user equipment that reduces the technical complexity and cost, while vastly expanding related applications. Additional satellites and signals, both more powerful and with improved designs, will increase the availability of robust signal reception outdoors and strengthen the potential of indoor positioning using only GNSS user equipment. But the path to the future is not without its risks: political, technical, economic, and cultural.

We present the results of experimental studies of electron content in the ionosphere over the territory of the Republic of Belarus based on data from global navigation satellite systems. The results of measurements of the precise positioning system of the Republic of Belarus and navigation data of GPS satellites in RINEX format were used as input data. Expressions for calculation of the total electron content using the two-frequency method and a combination of measurements by phase and code delays are given. Algorithms for eliminating cycle slip and determining differential code biases are used. Examples of calculating the vertical electron content over the Republic of Belarus at different moments of time are demonstrated. The obtained results are reasonable to use in monitoring of the ionosphere in order to provide reliable operation of radio systems, detection of ionospheric anomalies of natural and artificial origin, as well as forecasting of natural phenomena on their basis.

The importance and application of global navigation satellite systems (GNSS) has never been greater; there is increasing demand for both commercial and government projects; indeed, owning and operating a GNSS facility has become a matter of national esteem. This article reviews some of the history that led up to the USA building its benchmark Global Positioning System (GPS) exploiting electromagnetic waves and reviews the progress being made by other nations in constructing accurate navigation positioning systems.