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A particular problem in satellite communications is the estimation of the current operating point of a bent-pipe transponder. Various special effects aggravate this estimation problem, among which the capture effect, gain compression, unknown attenuation in the transmission channel, or noisy received signals are the most prominent. In most practical cases, operators desire a fully blind estimator...
For realization of ITS (Intelligent Transport Systems) world, location information is one of important information because the accuracy of the position decides the quality of ITS services. Kinematic positioning has been attracting attention as a high-precision position estimation method of moving objects. However, the acquisition rate of FIX solutions fluctuates according to positioning parameters...
Global Navigation Satellite System (GNSS) based navigation is already adopted in Low Earth Orbit (LEO), where the presence of strong GNSS signals and the good relative geometry between the receiver and the transmitters enable precise orbit determination. However, when the receiver is orbiting above the GNSS constellation's altitude, designing an on-board, real-time, autonomous GNSS navigation device...
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...
Considered as the free accessible and suitable solution for positioning in urban areas, Global Navigation Satellite Systems (GNSS) have been widely used these recent years in a wide spectrum of applications. However, signal blockage, non-line-of-sight (NLOS) multipath interferences and signal degradation affect the system performance and represent the major hurdles of GNSS in it course of adoption...
Satellite navigation is very widespread in civil society; many devices and services exploit this technology and several systems are in use or in development phase. GNSS receiver, embedded in devices used in daily life (smartphones, cars and so on), works in several conditions and operational scenarios. Ensuring good positioning accuracy is challenging, especially in environment where receiver measurements...
There are numerous uses of Global Navigation Satellite Systems (GNSS): navigation, of course, but also various optimizations, such as routing or handover protocols in telecommunication networks. Moreover, energy saving approaches may also be based on the use of the locations of the various entities involved. Most of the time, the positioning is considered to be “perfect”: no uncertainty on the values,...
The transmission of GNSS constellation-wide messages through multiple satellites can be more flexible than the transmission of clock and ephemeris by each satellite. Messages may be divided into packets and routed through different satellites to optimize reception performance. This paper proposes some basic routing strategies based on packet offsetting. It then proposes a performance analysis methodology...
A highly accurate and highly reliable navigation solution is essential for many applications like autonomous driving, augmented reality, or Unmanned Aerial Vehicles (UAVs). The key technology for all these applications is the Global Navigation Satellite System (GNSS), because it allows real-time positioning with global coverage and good long-term stability. To achieve a highly accurate solution at...
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...
N-FUELS (FUll Educational Library of Signals for Navigation) is a software-based generator of Global Navigation Satellite System (GNSS) signals [1]. One of the most relevant aspects of N-FUELS can be individuated in its versatility, being a collection of MATLAB® modules. This paper introduces a new module of N-FUELS suitable to simulate realistic GNSS signals from multiple satellites, with plausible...
Maintaining robust tracking and positioning integrity in harsh environments is a real challenge for GNSS receivers. This paper considers three possible tracking and navigation solutions to address this challenge. Firstly, a vector tracking loop (VTL) capable of using correlator-based multipath detectors and other signal quality indicators to exclude contaminated satellites from the PVT calculation...
Satellite operators need to know the operating point of a transponder to provide a good transmission quality. Especially in satellite networks with many small carriers in one transponder, the estimation is challenging because of gain compression, capture effects or unknown attenuation in the transmission channel. We propose a blind estimator based on signal statistics to overcome these problems. The...
This paper presents a novel tightly INS/GPS integration algorithm for altitude estimation. The altitude estimation is independent to provide accurate Euler angles for INS system, and magnetic sensors reduce the growth-rate of navigation-errors. In this paper, a tightly INS/GPS model is built with 23 state variables; bias and scale factor of IMU are estimated to correct INS system; and PVT information...
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...
Sensors play important roles for autonomous driving. Localization is definitely a key one. Undoubtedly, global positioning system (GPS) sensor will provide absolute localization for almost all the future land vehicles. In terms of driverless car, 1.5 m of positioning accuracy is the minimum requirement, since the vehicle has to keep in a driving lane that usually wider than 3 m. However, the skyscrapers...
Ground-Based Augmentation System (GBAS) allows high-precision aircraft landing based on Global Navigation Satellite System (GNSS) at large airports. However, non-uniform spatial ionospheric delay needs to be determined. In this work, we compute the nominal ionospheric delay gradients around Suvarnabhumi airport, Thailand. The utilized techniques involve Kalman filter and LAMBDA method. Based on the...
Compared with hardware receiver, the GPS software receiver has higher design flexibility, small size and low price, so it has a wide range of research prospects. In this paper, the GPS signal acquisition and tracking algorithm is studied. We use the collection and playback equipment to emulate the GPS signal and validate the acquisition and tracking algorithms. In the acquisition phase, the performance...
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...
Universidad Politécnica de Madrid (UPM) is participating in the Alphasat propagation experiment by measuring the copolar level of the Q-Band beacon at 39.4 GHz since April 2014. In this paper the results of the first two complete years of measurements (until March 2016) are presented with regards to excess and total attenuation. The reference level is calculated on an event-by-event basis in the first...
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