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

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.

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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):

Global Navigation Satellite Systems ◽

Observation Data ◽

International Gnss Service ◽

Satellite Systems ◽

Triple Frequency ◽

Software Packages ◽

Combined Solution ◽

Gnss Receivers ◽

Global Navigation Satellite ◽

Gnss Data

<p>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.</p>

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Assessment of geodetic products from MGEX analyses for the Onsala site

10.5194/egusphere-egu2020-965 ◽

2020 ◽

Author(s):

Periklis-Konstantinos Diamantidis ◽

Grzegorz Klopotek ◽

Rüdiger Haas

Keyword(s):

Global Navigation Satellite Systems ◽

Observation Data ◽

International Gnss Service ◽

Satellite Systems ◽

Troposphere Gradients ◽

Combined Solution ◽

Gnss Receivers ◽

Global Navigation Satellite ◽

Gnss Data

<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>

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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 ◽

Global Navigation Satellite Systems ◽

Electron Content ◽

Satellite Systems ◽

First Case ◽

Gnss Receivers ◽

Recent Phase ◽

Global Navigation Satellite ◽

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.

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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 ◽

Global Navigation Satellite Systems ◽

Receiver Design ◽

Software Receiver ◽

Satellite Systems ◽

Gnss Receivers ◽

Software Receivers ◽

Global Navigation Satellite ◽

Gnss Data

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

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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 ◽

Global Navigation Satellite Systems ◽

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.

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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 ◽

Global Navigation Satellite Systems ◽

Forward Speed ◽

Satellite Systems ◽

Different Shapes ◽

Global Navigation Satellite ◽

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.

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Experimental estimation of GNSS performances at the national aviation university

E3S Web of Conferences ◽

10.1051/e3sconf/202016403052 ◽

2020 ◽

Vol 164 ◽

pp. 03052

Author(s):

Volodymir Kharchenko ◽

Valeriy Konin ◽

Olexiy Pogurelsky ◽

Ekaterina Stativa

Keyword(s):

Experimental Data ◽

Continuous Monitoring ◽

Goal Achievement ◽

Global Navigation Satellite Systems ◽

Reference Station ◽

Satellite Systems ◽

Systems Quality ◽

Primary Focus ◽

Global Navigation Satellite ◽

Gnss Data

The goal of the research is to develop a of Global Navigation Satellite Systems quality monitoring methodology based on available equipment in the satellite navigation laboratory of the National Aviation University (Kyiv, Ukraine). For successful the goal achievement it is necessary to solve follow list of tasks: to determine the composition of the necessary equipment and order of it installing and connection; to develop the necessary software for processing received GNSS data; to estimate the GNSS characteristics with the help of experimental data. The primary focus of this research is on the following characteristics: accuracy (in terms of deviation coordinates in horizontal and vertical planes from the coordinates of the reference station and numerical values in meters); integrity information (summarized in the form of horizontal and Stanford plots); overall availability of service – measured as the availability of signals meeting the requirements for instrumented approaches with vertical guidance (APV) APV-1, APV-2, and Category 1 (CAT-1) precision approaches to runways. The main result of this research is developing software that could be applied for continuous monitoring of GNSS performances. The possibilities of it were successfully tested with the help of experimental data received from GPS and Galileo satellites.

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Node-Based Optimization of GNSS Tomography with a Minimum Bounding Box Algorithm

Remote Sensing ◽

10.3390/rs12172744 ◽

2020 ◽

Vol 12 (17) ◽

pp. 2744

Author(s):

Nan Ding ◽

Xiangrong Yan ◽

Shubi Zhang ◽

Suqin Wu ◽

Xiaoming Wang ◽

...

Keyword(s):

Global Navigation Satellite Systems ◽

Radiosonde Data ◽

New Approach ◽

Satellite Systems ◽

Bounding Box ◽

Percent Improvement ◽

The Common ◽

Gnss Network ◽

Global Navigation Satellite ◽

Mean Square Errors

Global Navigation Satellite Systems (GNSS) tomography plays an important role in the monitoring and tracking of the tropospheric water vapor. In this study, a new approach for improving the node-based GNSS tomography is proposed, which makes a trade-off between the real observed region and the complexity of the discretization of the tomographic region. To obtain dynamically the approximate observed region, the convex hull algorithm and minimum bounding box algorithm are used at each tomographic epoch. This new approach can dynamically define the tomographic model for all types of study areas based on the GNSS data. The performance of the new approach is tested by comparing it against the common node-based GNSS tomographic approach. Test data in May 2015 are obtained from the Hong Kong GNSS network to build the tomographic models and the radiosonde data as a reference are used for validating the quality of the new approach. The experimental results show that the root-mean-square errors of the new approach, in most cases, have a 38 percent improvement and the values of standard deviation reduce to over 43 percent compared with the common approach. The results indicate that the new approach is applicable to the node-based GNSS tomography.

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Validating HY-2A CMR Precipitable Water Vapor Using Ground-based and Shipborne GNSS Observations

10.5194/amt-2019-503 ◽

2020 ◽

Author(s):

Zhilu Wu ◽

Yanxiong Liu ◽

Yang Liu ◽

Jungang Wang ◽

Xiufeng He ◽

...

Keyword(s):

Water Vapor ◽

Microwave Radiometer ◽

Precipitable Water ◽

Global Navigation Satellite Systems ◽

High Temporal Resolution ◽

Satellite Systems ◽

The Indian Ocean ◽

Global Navigation Satellite ◽

Gnss Data ◽

Gnss Observations

Abstract. The calibration microwave radiometer (CMR) onboard Haiyang-2A satellite provides wet tropospheric delays correction for altimetry data, which can also contribute to the understanding of climate system and weather processes. Ground-based Global Navigation Satellite Systems (GNSS) provide precise PWV with high temporal resolution and could be used for calibration and monitoring of the CMR data, and shipborne GNSS provides accurate PWV over open oceans, which can be directly compared with uncontaminated CMR data. In this study, the HY-2A CMR water vapor product is validated using ground-based GNSS observations of 100 IGS stations along the coastline and 56-day shipborne GNSS observations over the Indian Ocean. The processing strategy for GNSS data and CMR data is discussed in detail. Special efforts were made to the quality control and reconstruction of contaminated CMR data. The validation result shows that HY-2A CMR PWV agrees well with ground-based GNSS PWV with 2.67 mm in RMS within 100 km. Geographically, the RMS is 1.12 mm in the polar region and 2.78 mm elsewhere. The PWV agreement between HY-2A and shipborne GNSS shows a significant correlation with the distance between the ship and the satellite footprint, with an RMS of 1.57 mm for the distance threshold of 100 km. Ground-based GNSS and shipborne GNSS agree with HY-2A CMR well with no obvious system error.

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Low cost GNSS receivers in time synchronization systems

Bulletin of the Military University of Technology ◽

10.5604/01.3001.0011.8035 ◽

2018 ◽

Vol 67 (1) ◽

pp. 65-72

Author(s):

Grzegorz Czopik ◽

Tomasz Kraszewski

Keyword(s):

Time Synchronization ◽

Low Cost ◽

Global Navigation Satellite Systems ◽

Satellite Systems ◽

Time Frequency ◽

Delay Times ◽

Gnss Receivers ◽

Frequency Counter ◽

The One ◽

Global Navigation Satellite

The GNSS (GNSS — Global Navigation Satellite Systems) receivers can be utilized to obtain accurate time markers. The preliminary results of the cheap GNSS receivers’ tests are presented in the paper. The one receiver’s price (including antenna) does not exceed 30 $. The studies on the use of receivers in the time synchronization systems were executed. Three identical models of receiver modules were used. The 1PPS (1PPS — 1 Pulse Per Second) signals available on the receiver’s output were used. The 1PPS’s main time characteristics were described. Delay times between different receivers 1PPS signals were measured. Measurements were taken using 1 GHz oscilloscope and precise time/frequency counter T3200U. Keywords: time synchronization, 1PPS, GNSS, GPS time

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