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Accurate and reliable positioning of vehicles is a decisive factor for many Intelligent Transportation System (ITS) applications. Under the cooperative environment, the eco-driving at specific scenarios, like intersections, requires vehicle motion state information, which can be provided by Global Navigation Satellite System (GNSS) with an integrity monitoring capability. In order to provide effective...
In this article, we discuss the important role of time-frequency (TF) signal representations in enhancing global navigation satellite system (GNSS) receiver performance. Both linear transforms and quadratic TF distributions (QTFDs) are considered. We review recent advances of antijam techniques that exploit the distinction in the TF signatures between the desired and undesired signals, enabling effective...
Mobile devices have been increasing in both number and power. While devices such as smartphones gain capabilities, an increasing number of users rely on them to complete more and more tasks. One of the most significant constraints of mobile devices is the necessary reliance on battery power. This limitation can be circumvented by operating the device while it is charging; however, this approach has...
Accurate and safe train position determination is of great importance for railway systems. Additionally, it has become one of the biggest challenges for the Safety-of-Life (SoL) services in railway transport systems using GNSS techniques. The critical performance requirements of these services promote the users to develop safe Train Positioning Systems (TPSs), in which integrity has to be highly concerned...
Archived GPS ephemeris data for years 2000–2016 is investigated by cleansing and precision measures. The goal of this work was twofold: (1) to reveal and remove incorrect ephemeris data so that the cleansed data is as close to the real broadcasted data as possible, and (2) to analyse the quality of the cleansed data by comparing ephemeris based satellite locations to true locations. Our findings show...
This paper describes special Ka- and Q-band receiver for the Alphasat signal developed for the Institute of Atmospheric Physics (IAP) Prague and first operational experiences with it. The signal level monitoring enables us to derive the atmospheric attenuation which is object of our research (its statistics and relation to relevant meteorological parameters like rain, liquid water content (LWC) and...
Near Vertical Incidence Skywave communication solutions are known to be reliable and quickly deployable, but modeling a suitable radio link requires a good prediction of the ionosphere behavior and insights regarding ionospheric propagation. Within the framework of the national PN-II SIRIUS project, the Technical University of Cluj-Napoca has acquired, installed, and employed the NovAtel GPStation-6...
Ionospheric scintillation monitoring is becoming an increasing research activity in order to devise countermeasures to the harmful effects ionospheric activity has on positioning services based on Global Navigation Satellite Systems (GNSS). The amount of amplitude fluctuations in GNSS signals due to scintillation is estimated by the �������� index. For this purpose, traditional closed loop architectures...
Advanced Receiver Autonomous Integrity Monitoring (ARAIM) is a new Aircraft Based Augmentation System (ABAS) technique, firstly presented in the two reports of the GNSS Evolutionary Architecture Study (GEAS). The ARAIM technique offers the opportunity to enable GNSS receivers to serve as a primary means of navigation, worldwide, for precision approach down to LPV-200 operation, while at the same time...
Ionospheric irregularities if persisted may lead to change in phase and amplitude of satellite signals and hence, ionospheric scintillation. Strong scintillation may induce loss of signal, cycle slips or excessive phase noise. The errors incurred by the radio signals could be disastrous especially to very sensitive agencies that make use of it if not properly managed. It is therefore pertinent to...
Malaysia has invested on public transport over the years to improve quality of leaving. Transportation has been identified as the key area in Malaysia's government transformation programme. In Malaysia, many people still choose to use their own transport compared to public transport to travel. For efficient public transport service such as bus, real-time tracking/monitoring must be available apart...
Location systems have known a very large scale spreading and developing in the last period, being known mainly through the navigation applications which ensure route guidance accordingly to the current position. This development was made possible by combining different localization modes (GPS, GLONASS, GPS-A etc.), which conduced to the precision required for developing a large number of specific...
The aim of this paper is to propose a complementary Health Management module to monitor the GPS accuracy for autonomous vehicles. Based on sensor information, the error causes of GPS can be observed in some specific contexts (urban, climate…). The proposed module relies on a Bayesian Network model that allows to reinforce the belief of GPS failure based on evidence. A hardware/software implementation...
Positioning errors of stand-alone GNSS can be reduced with different real-time augmentation approaches. For many navigation and positioning applications, Satellite-Based Augmentation System (SBAS) and Differential code-based GNSS (DGNSS) can offer substantial improvement in the positioning accuracy. Finland is covered by EGNOS (European Geostationary Overlay Service) even though it is lying at the...
In this paper, we get through some work to solve a detailed problem of the cesium active optical clock. With 459 nm laser pumping, the exact hyperfine energy levels between which the stimulated emission of Cs active optical clock takes place are studied.
For safety-of-life applications, such as landing an aircraft, the detection of ionospheric gradients is important both for the integrity of single frequency GBAS users as the availability for dual frequency users. In this paper an ionospheric gradient monitor is proposed, based on carrier phase observations. Carrier phase observations are very precise, but ambiguous. Although in aviation carrier phase...
Due to a rapid development of several Global Navigation Satellite Systems (GNSS), multiple constellations are available to enhance navigation performance and safety. With the growing number of satellite constellations, the task of the GNSS navigation is to deal with the differences among systems but, on the other hand, more great levels of integrity and satellite visibility can be expected. GNSS navigation...
As one possible continuation of development of Masat-1, the first Hungarian satellite, in 2015, a group of student, from Faculty of Electrical Engineering and Informatics and Mechanical Engineering, decided to realize a PocketQube-class satellite, called Smog-1. Smog-1 is a 5 cm cubesat as PocketQube with less than 180 g mass. The aim of Smog-1 is to measure the radio frequency (RF) smog caused by...
In recent years GNSS has become the recognised core element for the provision of accurate and reliable positioning, velocity and timing (PVT) data for multiple navigational applications. However, since the occurrence of strong ionospheric disturbances impacts the accuracy of GNSS measurements leading consequently to unreliable PVT solutions, not only precision and accuracy but also high-level reliability...
The development of new GNSS constellations, and the modernization of existing ones, has increased the availability and the number of satellites-in-view, paving the way for new navigation algorithms and techniques. These offer the opportunity to improve the navigation performance while at the same time potentially reducing the support which has to be provided by Ground and Satellite Based Augmented...
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