Assessment of geodetic products from MGEX analyses for the Onsala site

Observation Data ◽

Satellite Systems ◽

Troposphere Gradients ◽

Combined Solution ◽

Gnss Receivers ◽

<div>The emergence of BeiDou and Galileo as operational Global Navigation Satellite Systems (GNSS), in addition to Global Positioning System (GPS) and GLONASS which are already in use, opens up possibilities in delivering geodetic products with higher precision. Apart from ensuring the homogeneity of the derived products, multi-GNSS analysis takes the advantage of new frequencies and an improved sky coverage. This should lead to better phase ambiguity resolution and an improved estimation of target parameters such as zenith wet delays (ZWD), troposphere gradients (GRD) and station positions. The International GNSS Service (IGS) has realised this potential by initiating the Multi-GNSS Experiment (MGEX) which provides orbit, clock and observation data for all operational GNSS. Correspondingly, the multi-technique space geodetic analysis software c5++ has been augmented with a MGEX-compliant GNSS module. Based on this new module and the Precise Point Positioning (PPP) approach using six-month of data, an assessment of the derived geodetic products is carried out for several GNSS receivers located at the Onsala core site. More specifically, we perform both single- and multi-GNSS data analysis using Kalman filter and least-squares methods and assess the quality of the derived station positions, ZWD and GRD. A combined solution using all GNSS together is carried out and the improvement with respect to station position repeatabilities is assessed for each station. Inter-system biases, which homogenise the different time scale that each GNSS operates in and are necessary for the multi-GNSS combination, are estimated and presented. Finally, the applied inter-system weighting is discussed as well as its impact on the derived geodetic products.</div>

Assessment of geodetic products from Multi-GNSS analyses at the Onsala site

10.5194/egusphere-egu21-14343 ◽

2021 ◽

Author(s):

Periklis-Konstantinos Diamantidis ◽

Grzegorz Kłopotek ◽

Rüdiger Haas ◽

Jan Johansson

Keyword(s):

Observation Data ◽

Satellite Systems ◽

Triple Frequency ◽

Software Packages ◽

Combined Solution ◽

Gnss Receivers ◽

The dawn of Beidou and Galileo as operational Global Navigation Satellite Systems (GNSS) alongside Global Positioning System (GPS) and GLONASS as well as new features that are now present in all GNSS, such as a triple-frequency setup, create new possibilities concerning improved estimation and assessment of various geodetic products. In particular, the multi-GNSS analysis gives an access to a better sky coverage allowing for improved estimation of zenith wet delays (ZWD) and tropospheric gradients (GRD), and can be used to determine integer phase ambiguities. The Multi-GNSS Experiment (MGEX), as realised by the International GNSS Service (IGS), provides orbit, clock and observation data for all operational GNSS. To take advantage of the new capabilities that these constellations bring, space-geodetic software packages have been retrofitted with Multi-GNSS-compliant modules. Based on this, two software packages, namely GipsyX and c5++, are utilised by way of the static Precise Point Positioning (PPP) approach using six months of data, and an assessment of the derived geodetic products is carried out for several GNSS receivers located at the Onsala core site. More specifically, we perform both single-constellation and multi-GNSS data analysis using Kalman filter and least-squares methods and assess the quality of the derived station positions, ZWD and GRD. A combined solution using all GNSS constellations is carried out and the improvement with respect to station position repeatabilities is assessed for each station. Results from the two software packages are compared with respect to each other and the discrepancies are discussed. Inter-system biases, which homogenise the different time scale that each GNSS operates in, and are necessary for the multi-GNSS combination, are estimated and presented. Finally, the applied inter-system weighting and its impact on the derived geodetic products are discussed.

Towards FAIR GNSS data: challenges and open problems

10.5194/egusphere-egu2020-18398 ◽

2020 ◽

Author(s):

Anna Miglio ◽

Carine Bruyninx ◽

Andras Fabian ◽

Juliette Legrand ◽

Eric Pottiaux ◽

...

Keyword(s):

Research Policy ◽

Open Problems ◽

Data Repositories ◽

Satellite Systems ◽

Data Practices ◽

Metadata Standards ◽

Nowadays, we measure positions on Earth&#8217;s surface thanks to Global Navigation Satellite Systems (GNSS) e.g. GPS, GLONASS, and Galileo. Activities such as navigation, mapping, and surveying rely on permanent GNSS tracking stations located all over the world. The Royal Observatory of Belgium (ROB) maintains and operates a repository containing data from hundreds of GNSS stations belonging to the European GNSS networks (e.g. EUREF, Bruyninx et al., 2019).&#160;ROB&#8217;s repository contains GNSS data that are openly available and rigorously curated. The curation data include detailed GNSS station descriptions (e.g. location, pictures, and data author) as well as quality indicators of the GNSS observations.However, funders and research policy makers are progressively asking for data to be made Findable, Accessible, Interoperable, and Reusable (FAIR) and therefore to increase data transparency, discoverability, interoperability, and accessibility.In particular, within the GNSS community, there is no shared agreement yet on the need for making data FAIR. Therefore, turning GNSS data FAIR presents many challenges and, although FAIR data has been included in EUREF&#8217;s strategic plan, no practical roadmap has been implemented so far. We will illustrate the specific difficulties and the need for an open discussion including also other communities working on FAIR data.For example, making GNSS data easily findable and accessible would require to attribute persistent identifiers to the data. It is worth noting that the International GNSS Service (IGS) is only now beginning to consider the attribution of DOIs (Digital Object Identifiers) to GNSS data, mainly to allow data citation and acknowledgement of data providers. Some individual GNSS data repositories are using DOIs (such as UNAVCO, USA).&#160; Are DOIs the only available option or are there more suitable types of URIs (Uniform Resource Identifiers) to consider?The GNSS community would greatly benefit from FAIR data practices, as at present, (almost) no licenses have been attributed to GNSS data, data duplication is still an issue, historical provenance information is not available because of data manipulations in data centres, citation of the data providers is far from the rule, etc.To move further along the path towards FAIR GNSS data, one would need to implement standardised metadata models to ensure data interoperability, but, as several metadata standards are already in use in various scientific disciplines, which one to choose?Then, to facilitate the reuse (and long-term preservation) of GNSS data, all metadata should be properly linked to the corresponding data and additional metadata, such as provenance and license information. The latter is a good example up for discussion: despite the fact that &#8216;CC BY&#8217; license is already assigned to some of the GNSS data, other licenses might need to be enabled.&#160;Bruyninx C., Legrand J., Fabian A., Pottiaux E. (2019) &#8220;GNSS Metadata and Data Validation in the EUREF Permanent Network&#8221;. GPS Sol., 23(4), https://doi: 10.1007/s10291-019-0880-9&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;

Linear and Nonlinear Deformation Effects in the Permanent GNSS Network of Cyprus

Sensors ◽

10.3390/s20061768 ◽

2020 ◽

Vol 20 (6) ◽

pp. 1768

Author(s):

Chris Danezis ◽

Miltiadis Chatzinikos ◽

Christopher Kotsakis

Keyword(s):

Crustal Deformation ◽

Satellite Systems ◽

Time Period ◽

Position Time Series ◽

Gnss Receivers ◽

Linear And Nonlinear ◽

Gnss Network ◽

Permanent Global Navigation Satellite Systems (GNSS) reference stations are well established as a powerful tool for the estimation of deformation induced by man-made or physical processes. GNSS sensors are successfully used to determine positions and velocities over a specified time period, with unprecedented accuracy, promoting research in many safety-critical areas, such as geophysics and geo-tectonics, tackling problems that torment traditional equipment and providing deformation products with absolute accuracy. Cyprus, being located at the Mediterranean fault, exhibits a very interesting geodynamic regime, which has yet to be investigated thoroughly. Accordingly, this research revolves around the estimation of crustal deformation in Cyprus using GNSS receivers. CYPOS (CYprus POsitioning System), a network of seven permanent GNSS stations has been operating since 2008, under the responsibility of the Department of Lands and Surveys. The continuous flow of positioning data collected over this network, offers the required information to investigate the behavior of the crustal deformation field of Cyprus using GNSS sensors for the first time. This paper presents the results of a multi-year analysis (11/2011–01/2017) of daily GNSS data and provides inferences of linear and nonlinear deforming signals into the position time series of the network stations. Specifically, 3D station velocities and seasonal periodic displacements are jointly estimated and presented via a data stacking approach with respect to the IGb08 reference frame.

MONITOR Ionospheric Network: two case studies on scintillation and electron content variability

Annales Geophysicae ◽

10.5194/angeo-35-377-2017 ◽

2017 ◽

Vol 35 (3) ◽

pp. 377-391 ◽

Cited By ~ 6

Author(s):

Yannick Béniguel ◽

Iurii Cherniak ◽

Alberto Garcia-Rigo ◽

Pierrick Hamel ◽

Manuel Hernández-Pajares ◽

...

Keyword(s):

Case Studies ◽

Electron Content ◽

Satellite Systems ◽

First Case ◽

Gnss Receivers ◽

Recent Phase ◽

Gnss Data ◽

High Frequency Sampling

Abstract. The ESA MONITOR network is composed of high-frequency-sampling global navigation satellite systems (GNSS) receivers deployed mainly at low and high latitudes to study ionosphere variability and jointly with global GNSS data and ionospheric processing software in support of the GNSS and its satellite-based augmentation systems (SBAS) like the European EGNOS. In a recent phase of the project, the network was merged with the CNES/ASECNA network and new receivers were added to complement the latter in the western African sector. This paper summarizes MONITOR, presenting two case studies on scintillations (using almost 2 years of data measurements). The first case occurred during the major St. Patrick's Day geomagnetic storm in 2015. The second case study was performed in the last phase of the project, which was supported by ESA EGNOS Project Office, when we paid special attention to extreme events that might degrade the system performance of the European EGNOS.

Establishment of Karadeniz Technical University Permanent GNSS Station as Reactivated of TRAB IGS Station

Geodesy and Cartography ◽

10.1515/geocart-2017-0014 ◽

2017 ◽

Vol 66 (2) ◽

pp. 253-258

Author(s):

Selma Zengin Kazancı ◽

Emine Tanır Kayıkçı

Keyword(s):

Weather Prediction ◽

Reference Station ◽

Observation Data ◽

Satellite Systems ◽

Gnss Meteorology ◽

Station Coordinates ◽

Technical University ◽

Global Navigation Satellite

Abstract In recent years, Global Navigation Satellite Systems (GNSS) have gained great importance in terms of the benefi ts it provides such as precise geodetic point positioning, determining crustal deformations, navigation, vehicle monitoring systems and meteorological applications etc. As in Turkey, for this purpose, each country has set up its own GNSS station networks like Turkish National Permanent RTK Network analyzed precise station coordinates and velocities together with the International GNSS Service, Turkish National Fundamental GPS Network and Turkish National Permanent GNSS Network (TNPGN) stations not only are utilized as precise positioning but also GNSS meteorology studies so total number of stations are increased. This work is related to the reactivated of the TRAB IGS station which was established in Karadeniz Technical University, Department of Geomatics Engineering. Within the COST ES1206 Action (GNSS4SWEC) KTU analysis center was established and Trop-NET system developed by Geodetic Observatory Pecny (GOP, RIGTC) in order to troposphere monitoring. The project titled “Using Regional GNSS Networks to Strengthen Severe Weather Prediction” was accepted to the scientifi c and technological research council of Turkey (TUBITAK). With this project, we will design 2 new constructed GNSS reference station network. Using observation data of network, we will compare water vapor distribution derived by GNSS Meteorology and GNSS Tomography. At this time, KTU AC was accepted as E-GVAP Analysis Centre in December 2016. KTU reference station is aimed to be a member of the EUREF network with these studies.

Multi-GNSS Software Receiver Design Optimization for Accuracy Improvement

International Journal for Research in Applied Science and Engineering Technology ◽

10.22214/ijraset.2021.38190 ◽

2021 ◽

Vol 9 (9) ◽

pp. 1467-1476

Author(s):

Jasmien Hassanien

Keyword(s):

Multipath Fading ◽

Least Square ◽

Receiver Design ◽

Software Receiver ◽

Satellite Systems ◽

Gnss Receivers ◽

Software Receivers ◽

Abstract: Recently, tremendous research has been conducted on Global navigation satellite systems (GNSS) software receivers to better serve the current challenging environments that suffers from multipath fading. Therefore, the development of GNSS receivers has seen a new rush toward a multi-GNSS as a solution for fading problems. In this paper, a multi-GNSS software receiver is designed, optimized, and its performance is presented. The implemented software receiver covers three different signals from two GNSS constellations, namely GPS L1, GPS L2, and Galileo E1. In this paper. the fundamentals of stages of GNSS signal reception (acquisition, tracking, and navigation) are discussed where each stage is customized and optimized for each considered signal and the stage of mutli-GNSS data combination is optimized afterword. The performance of the optimized multi-GNSS software receiver is examined under different combination scenarios where the Least-Square Estimation (LSE) method using precise positioning (PP) algorithms is adopted. Results showed that using multi-GNSS receiver enhances the accuracy of Position, Velocity, and Timing (PVT) solution. Keywords: GNSS, PVT, GPS, Galileo, and accuracy

Technical Considerations for Modernizing Nova Scotia’s Coordinate Referencing System

GEOMATICA ◽

10.5623/cig2016-201 ◽

2016 ◽

Vol 70 (2) ◽

pp. 85-96 ◽

Cited By ~ 1

Author(s):

Jason Bond

Keyword(s):

Passive Control ◽

Observation Data ◽

Crowd Sourcing ◽

Satellite Systems ◽

Network Location ◽

Land Administration ◽

New Strategy ◽

Technical Considerations

The Nova Scotia Coordinate Referencing System (NSCRS) is Nova Scotia's current framework for providing location-based information. The NSCRS is the foundation for the province's geographic data, includ ing the land administration system. In 2012, the province began developing a modernization strategy to better execute its coordinate referencing program to address ongoing accuracy and accessibility needs. A net work of active control stations (ACSs) tracking global navigation satellite systems (GNSS) is at the core of the new strategy. In addition to providing better accuracy and accessibility to the NSCRS, the tech nol ogy has created new opportunities to sustain its passive control infrastructure. In 2015, the installation of 40 ACSs across the province was completed, providing industry with access to real-time, centimetre-level positioning. Over the course of the NSCRS modernization project, several tech nical considerations needed to be addressed pertaining to the design of the network, location of the ACSs, flow of the ACS data and the crowd sourcing of GNSS observation data to maintain the passive con trol sys tem. These technical considerations are reviewed and the solutions implemented to address the needs of this initiative are presented.

EVALUATION AND TAILORING OF GLOBAL GEOPOTENTIAL MODELS IN THE DETERMINATION OF GRAVITY FIELD IN SERBIA

САВРЕМЕНА ТЕОРИЈА И ПРАКСА У ГРАДИТЕЉСТВУ ◽

10.7251/stp2014077o ◽

2020 ◽

Vol 14 (1) ◽

Author(s):

Oleg Odalović ◽

Danilo Joksimović ◽

Dušan Petković ◽

Marko Stanković ◽

Sanja Grekulović

Keyword(s):

Satellite Systems ◽

Average Value ◽

Free Air ◽

Geopotential Models ◽

Normal Heights ◽

Discrete Values ◽

Global Navigation Satellite

Within this paper, we evaluated the quality of three Global Geopotential Models entitled: EGM96,EGM2008, and GOCO05c. The models were evaluated by using 1001 terrestrial discrete values ofheight anomalies determined by Global Navigation Satellite Systems and normal heights, which weconsidered to be true values within this research. In addition to the quality evaluation, we tailoredthe models by using more than 80000 free air anomalies. The results obtained from the evaluationand tailoring indicate that by using the GOCO05c it is possible to determine a set of anomaly heightsacross Serbia, which are in agreement with terrestrial values with an average value of -7 cm, thestandard deviation of ±9 cm and with the range of 44 cm.

Seamless Vehicle Positioning by Lidar-GNSS Integration: Standalone and Multi-Epoch Scenarios

Remote Sensing ◽

10.3390/rs13224525 ◽

2021 ◽

Vol 13 (22) ◽

pp. 4525

Author(s):

Junjie Zhang ◽

Kourosh Khoshelham ◽

Amir Khodabandeh

Keyword(s):

Autonomous Driving ◽

Measurement Model ◽

Urban Environments ◽

High Definition ◽

Satellite Systems ◽

The Road ◽

Gnss Receivers ◽

Vehicle Positioning ◽

Global Navigation Satellite

Accurate and seamless vehicle positioning is fundamental for autonomous driving tasks in urban environments, requiring the provision of high-end measuring devices. Light Detection and Ranging (lidar) sensors, together with Global Navigation Satellite Systems (GNSS) receivers, are therefore commonly found onboard modern vehicles. In this paper, we propose an integration of lidar and GNSS code measurements at the observation level via a mixed measurement model. An Extended Kalman-Filter (EKF) is implemented to capture the dynamic of the vehicle movement, and thus, to incorporate the vehicle velocity parameters into the measurement model. The lidar positioning component is realized using point cloud registration through a deep neural network, which is aided by a high definition (HD) map comprising accurately georeferenced scans of the road environments. Experiments conducted in a densely built-up environment show that, by exploiting the abundant measurements of GNSS and high accuracy of lidar, the proposed vehicle positioning approach can maintain centimeter-to meter-level accuracy for the entirety of the driving duration in urban canyons.

Assessment of the Cutting Performance of a Robot Mower Using Custom Built Software

Agronomy ◽

10.3390/agronomy9050230 ◽

2019 ◽

Vol 9 (5) ◽

pp. 230 ◽

Cited By ~ 4

Author(s):

Luisa Martelloni ◽

Marco Fontanelli ◽

Stefano Pieri ◽

Christian Frasconi ◽

Lisa Caturegli ◽

...

Keyword(s):

Autonomous Vehicles ◽

Forward Speed ◽

Satellite Systems ◽

Different Shapes ◽

High Level ◽

Short Time ◽

Gnss Data ◽

Collection And Management

Before the introduction of positioning technologies in agriculture practices such as global navigation satellite systems (GNSS), data collection and management were time-consuming and labor-intensive tasks. Today, due to the introduction of advanced technologies, precise information on the performance of agricultural machines, and smaller autonomous vehicles such as robot mowers, can be collected in a relatively short time. The aim of this work was to track the performance of a robot mower in various turfgrass areas of an equal number of square meters but with four different shapes by using real-time kinematic (RTK)-GNSS devices, and to easily extract data by a custom built software capable of calculating the distance travelled by the robot mower, the forward speed, the cutting area, and the number of intersections of the trajectories. These data were then analyzed in order to provide useful functioning information for manufacturers, entrepreneurs, and practitioners. The path planning of the robot mower was random and the turfgrass area for each of the four shapes was 135 m2 without obstacles. The distance travelled by the robot mower, the mean forward speed, and the intersections of the trajectories were affected by the interaction between the time of cutting and the shape of the turfgrass. For all the different shapes, the whole turfgrass area was completely cut after two hours of mowing. The cutting efficiency decreased by increasing the time, as a consequence of the increase in overlaps. After 75 minutes of cutting, the efficiency was about 35% in all the turfgrass areas shapes, thus indicating a high level of overlapping.