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Fugro is operating a global GNSS infrastructure for the delivery of high-accuracy multi-constellation Precise Point Positioning (PPP) service, named G4. Precise orbit and clock for all global satellite navigation systems are estimated in real-time and broadcast to the users using geostationary satellites. End-users with a G4-enabled receiver are ab...
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Context 1
... G4 system high-level architecture is depicted in Figure 1. The G4 network consists of 45 multi-GNSS reference tracking stations, worldwide distributed ( Figure 2). For redundancy reasons, two different receiver brands are used in the network. ...
Context 2
... are then forwarded simultaneously to two Network Control Centres (NCCs), located in Houston (USA) and Perth (Australia). The NCCs generate the final correction streams (including UPDs) and broadcast them to the users via eight geostationary satellites, whose coverage is depicted in Figure 2. At any given location below about 75° latitude, the user can typically observe two geostationary satellites simultaneously. ...
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The use of global navigation satellite systems (GNSS) has been a competitive way to provide high-precision and low-cost time and frequency transfer results. However, the traditional GNSS method, the precise point positioning (PPP), is usually based on the ionosphere-free (IF) combination, which is not flexible when applying multi-frequency scenario...
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Real-time satellite clock offsets are key in realizing real-time precise point positioning (PPP). Typically, tens of minutes are required for re-convergence because many tropospheric and ambiguity parameters are estimated in the clock offset estimation when the interruption of observation data occasionally occurs. This contribution proposes a rapid...
Citations
... The positioning accuracy requirements of each maritime navigation phase are given in Table 1. The performance of the kinematic GNSS PPP solution in hydrographic and maritime applications has been investigated by a number of researchers (e.g., Alkan and Ocalan, 2013;El-Diasty and Elsobeiey, 2015;Berber and Wright, 2016;El-Diasty, 2016;Akpınar and Aykut, 2017;Alkan et al., 2017;Tegedor et al., 2017;Farah 2018;Specht et al., 2019;Yang et al., 2019;Erol 2020;Erol et al., 2020;Alkan et al., 2020;Tunalioglu et al., 2022). Yang et al. (2019) investigated the accuracy of the GPS/GLONASS/BeiDou RTK PPP solution for maritime applications. ...
Our research aims to evaluate the triple-frequency GPS/Galileo/BeiDou kinematic precise point positioning (PPP) accuracy for the international maritime organization (IMO) positioning accuracy and integrity requirements. The real-time Centre National d’Etudes Spatiales (CNES) satellite orbit and clock products are used to simulate real-time scenarios. GPS/Galileo/BeiDou observations are collected from a moving vessel. Both dual-frequency and triple-frequency ionosphere-free PPP models are developed. Different satellite system combinations are used, including GPS-only, GPS/Galileo, GPS/BeiDou, and GPS/Galileo/BeiDou. The GPS-only differential solution is used as a reference. It is found that both dual- and triple-frequency kinematic PPP solutions achieve the IMO accuracy requirements at 95% confidence level for ocean, coastal, port approach, port, inland waterways, and track control navigation applications, except the automatic docking application. Moreover, the PPP solutions fulfilled the IMO integrity requirements for all navigation phase applications, but the GPS and GPS/BeiDou PPP solutions did not fulfill the automatic docking integrity requirement.
... When it comes to studies conducted in the past on the accuracy for marine applications achieved in real time by GNSS standalone and with the addition of augmentations, review of the literature indicates that GNSS standalone accuracy is in the order of a few meters [10] and performance is slightly improved to submeter accuracy with the use of DGNSS [11] or SBAS [12], and to centimeter accuracy using commercial services or postprocessing [13]. ...
Global Navigation Satellite System (GNSS) technology supports all phases of maritime navigation and serves as an integral component of the Automatic Identification System (AIS) and, by extension, Vessel Traffic Service (VTS) systems. However, the accuracy of standalone GNSS is often insufficient for specific operations. To address this limitation, various regional and local-area solutions have been developed, such as Differential GNSS (DGNSS), Satellite Based Augmentation Service (SBAS) and Real Time Kinematic (RTK) techniques. A notable development in this field is the recent introduction of the Galileo High-Accuracy Service (HAS), which saw its initial service declared operational by the European Commission (EC) on 24 January 2023. Galileo HAS provides high-accuracy Precise Point Positioning (PPP) corrections (orbits, clocks and signal biases) for Galileo and GPS, enhancing real-time positioning performance at no additional cost to users. This article presents the results of the first Galileo HAS testing campaign conducted at sea using a buoy-laying vessel temporarily equipped with a Galileo HAS User Terminal. The results presented in this Article include accuracy and position availability performance achieved using the Galileo HAS User Terminal. The article also highlights challenges posed by high-power radio-frequency interference, which likely originated from the Long-Range Identification and Tracking (LRIT) system antenna on board the vessel. Furthermore, the article provides additional assessments for different phases of navigation, demonstrating better performance in slow-motion scenarios, particularly relevant to mooring and pilotage applications. In these scenarios, values for horizontal accuracy reached 0.22 m 95% and 0.13 m 68% after removing interference periods. These results are in line with the expectations outlined in the Galileo HAS Service Definition Document (SDD).
... This application example selects two scenarios. The goal is to drive the test vehicle to the entrance of the indoor parking lot and enter the intersection of indoor and outdoor positioning environments [24]. With the above limitations, this chapter exports the above positioning data. ...
Navigation and positioning is a new growth point of wireless services. And seamless positioning is the current development trend of navigation and positioning services. In view of the problems that dynamic handover cannot be performed during site movement, STA only selects the optimal AP according to the indication of received signal strength, and the handover delay is too long. This paper proposes a research on indoor and outdoor seamless positioning technology based on artificial intelligence and intelligent switching algorithm. The purpose is to study the influence of reducing the positioning data with too large error on the final positioning result. The method of this paper is to propose an intelligent switching algorithm and then discuss the research status and development direction of indoor positioning technology and outdoor positioning technology, respectively, and point out the switching methods between them. The role of these methods is to analyze the current situation of indoor and outdoor navigation technology, especially the development route of seamless positioning technology. It determines the strategy of integrating heterogeneous positioning systems to build a seamless positioning system to maximize the use of existing positioning system resources. This paper studies the design and implementation of the seamless positioning system through the simulation experiment of the intelligent switching algorithm and finally tests the system through the experimental vehicle. The online experiment results show that the system can achieve high positioning accuracy in indoor and outdoor environments, especially at its junction, and the positioning errors in all directions are within 0.2 m.
... One of the recent advancements of PPP is the availability of realtime GNSS precise orbit and clock corrections that can be provided by geostationary (GEO) satellites. There are some commercial services, such as G4 from Fugro (Tegedor et al. 2017) and TerraStar-D (Jokinen et al. 2014) that can provide such a service. In addition to the commercial services, the Japanese Quasi-Zenith Satellite System (QZSS) also provides the orbits and clock corrections through the L6 signal broadcast by the navigation satellites (Cabinet Office 2020) within the Multi-GNSS Advanced Demonstration Tool for Orbit and Clock Analysis (MADOCA) service. ...
Precise orbit determination (POD) is the procedure for determining the orbit of a satellite with high accuracy. Compared with global navigation satellite systems (GNSS), the low Earth orbit (LEO) satellites have some different features in space, mainly due to perturbations caused by dynamic forces related to their altitudes. Methods for POD of LEO satellites have been developed over the last decades. Nowadays, postprocessed precise orbits are used in different space applications such as radio occultation, satellite altimetry, and interferometric synthetic-aperture radar missions. The advancements in technology decrease the size of LEO satellites and developments in theory increase their orbital accuracy. In recent years, onboard POD has become a hot topic in the navigation and positioning field, which is crucial for, e.g., formation flying of small satellites and GNSS-aided LEO megaconstellations for positioning purposes. This contribution reviews LEO POD methods based on undifferenced GNSS observations in both postmission and real-time data processing. It comprises the quality control step, the models used and their limitations, processing algorithms, and different validation methods. To have a clear insight into the current and the future state of the LEO POD, the most recent developments and important achievements are also discussed.
... For this purpose, different platforms and systems are available for supporting the connectivity of the devices at the surface, e.g., the Automatic Identification System (AIS) [20] based on Very High Frequency (VHF) radio [21] or the wireless network technology Mobile ad-hoc Networks (MANETs), to give basic information such as identification, location, speed, course or destination of the marine devices, etc. [22]. For navigation, the Global Positioning System (GPS), Glogal´naya Navigatsionnaya Sputnikovaya Systema (GLONASS) [23], or new high-accuracy systems such as Precise Point Positioning (PPP) [24] in a Global Navigation System (GNSS) integration are employed [25]. Telecommunications underwater are more complex and complicated because electromagnetic signals are highly attenuated and therefore have a low transmission range [26]. ...
The ENDURUNS project is a European Research project of the Horizon 2020 framework, which has as its main objective to achieve the optimum and intelligent use of green hydrogen energy for long-term ocean surveys. The ENDURUNS system comprises an Unmanned Surface Vehicle (USV) and an Autonomous Underwater Vehicle (AUV) with gliding capability. The power pack of the USV integrates Li-ion batteries with photovoltaic panels, whilst the AUV employs Li-ion batteries and a hydrogen fuel cell. It is essential to develop a continuous monitoring ca-pability for the different systems of the vehicles. Data transmission between the devices onboard presents challenges due to the volume and structure of the different datasets. A telecommunications network has been designed to manage the operational components considered in the project. The autonomous vehicles perform measurements, providing their position and other data wirelessly. The system will generate a great volume of various signals during the survey. The Remote Control Centre needs to be interfaced with the vehicles in order to receive, manage and store the acquired data. An Underwater Internet of Things (IoT) platform is designed to establish efficient and smart data management. This study presents an exhaustive survey to analyse the telecommunication systems employed in the autonomous vehicles, including the back-end, user interface and mobile units. This paper presents the novel design of the hardware and software structure of the ENDURUNS project with regard to the literature, where its components and their in-terconnection layers are detailed, which is a novel scientific and technological approach for autonomous seabed surveying in deep oceans or in coastal areas.
... Using the IGS ultra-rapid products, the orbital accuracy of the GRACE and TerraSAR-X satellites has also reached dm level (Montenbruck et al. 2005;Wermuth et al. 2012). In addition to the Internet-linked real-time GNSS products, the precise orbits and clocks can also be obtained directly through the geostationary earth orbit (GEO) link from commercial services (Tegedor et al. 2017). As tested in a simulation study for the onboard LEO POD, a promising 3D accuracy of sub-dm level can be achieved using the Fugro G4 service (Hauschild et al. 2016). ...
For real-time precise orbit determination (POD) of low earth orbit (LEO) satellites, high-accuracy global navigation satellite system (GNSS) orbit and clock products are necessary in real time. Recently, the Japanese multi-GNSS advanced demonstration of orbit and clock analysis precise point positioning (PPP) service and the new generation of the Australian/New Zealand satellite-based augmentation system (SBAS)-aided PPP service provide free and precise GNSS products that are directly broadcast through the navigation and geostationary earth orbit satellites, respectively. With the high quality of both products shown in this study, a 3D accuracy of centimeters can be achieved in the post-processing mode for the reduced-dynamic orbits of small LEO satellites having a duty cycle down to 40% and at sub-dm to dm level for the kinematic orbits. The results show a promising future for high-accuracy real-time POD onboard LEO satellites benefiting from the precise free-of-charge PPP corrections broadcast by navigation systems or SBAS.
... kleiner als 75° mind. zwei geostationäre Satelliten sichtbar sind. Diese übertragen die Korrekturen via L-Band und können mit Standard-GNSS-Antennen empfangen werden. Um diesen Korrekturservice von Fugro nutzen zu können, muss ein entsprechender Empfänger, welcher die Informationen des L-Band Signal decodieren und verarbeiten kann, vorhanden sein (Tegedor et. al. 2017). Für statische Anwendungen werden die horizontale Genauigkeit mit ca. 1-2 cm (1sigma) bzw. 5,9 cm (95% Vertrauensbereich) und die vertikale Genauigkeit mit 4-5 cm (1-sigma) bzw. 10,1 (95% Vertrauensbereich) angegeben. Die Konvergenzzeit beträgt ca. 20 min und entspricht somit der üblichen PPP-Konvergenzzeit. Genauigkeitsuntersuchungen b ...
... kale Genauigkeit mit 4-5 cm (1-sigma) bzw. 10,1 (95% Vertrauensbereich) angegeben. Die Konvergenzzeit beträgt ca. 20 min und entspricht somit der üblichen PPP-Konvergenzzeit. Genauigkeitsuntersuchungen basierend auf Basislinienauswertungen zweier Antennen auf dem Schiff, lassen ein ähnliches Genauigkeitsniveau für kinematische Anwendungen vermuten (Tegedor et. al 2017, Visser 2015. ...
... Aber auch die beschriebenen Echtzeit-PPP-Dienste Fugro, Trimble Centerpoint RTX und StarFire nutzen zum Teil diese Art der Kommunikation für die Korrekturdatenübertragung (Tegedor et. al 2017, Leandro R. 2011. Dem Vorteil der Satellitenkommunikation einer stabilen Datenübertragung steht der Nachteil einer geringen Bandbreite gegenüber. Für die Übertragung von RTK-Korrekturen ist es daher eher nicht geeignet. ...
CubeSats are faced with some limitations, mainly due to the limited onboard power and the quality of the onboard sensors. These limitations significantly reduce CubeSats' applicability in space missions requiring high orbital accuracy. This thesis first investigates the limitations in the precise orbit determination of CubeSats and next develops algorithms and remedies to reach high orbital and clock accuracies. The outputs would help in increasing CubeSats' applicability in future space missions.
