scholarly journals Rapid Static Positioning Using a Four System GNSS Receivers in the Forest Environment

Forests ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 45
Author(s):  
Michał Brach
Keyword(s):  
Main Idea ◽  
Global Navigation Satellite Systems ◽  
Forest Environment ◽  
Large Variability ◽  
Satellite Systems ◽  
Forest Inventories ◽  
Cycle Slips ◽  
Gnss Receivers ◽  
Global Navigation Satellite ◽  
Rapid Static Positioning

Global Navigation Satellite Systems (GNSS) are crucial elements used in forest inventories. Forest metrics modeling efficacy depends on the accuracy of determining sample plot locations by GNSS. As of 2021, the GNSS consists of 120 active satellites, ostensibly improving position acquisition in forest conditions. The main idea of this article was to evaluate GIS-class and geodetic class GNSS receivers on 33 control points located in the forest. The main assumptions were operating on four GNSS systems (GPS, GLONASS, Galileo, and BeiDou), keeping a continuous online connection to the network of reference stations, maintaining occupation time-limited to 60 epochs, and repeating all the measurements three times. Rapid static positioning was tested, as it compares the true performance of the four GNSS systems receivers. Statistical differences between the receivers were confirmed. The GIS-class receiver achieved an accuracy of 1.38 m and a precision of 1.29 m, while the geodetic class receiver reached 0.74 m and 0.91 m respectively. Even though the research was conducted under the same data capture conditions, the large variability of positioning results were found to be caused by cycle slips and the multipath effect.

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

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.

scholarly journals Low cost GNSS receivers in time synchronization systems

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

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

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1768
Author(s):  
Chris Danezis ◽  
Miltiadis Chatzinikos ◽  
Christopher Kotsakis
Keyword(s):  
Crustal Deformation ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Time Period ◽  
Position Time Series ◽  
Gnss Receivers ◽  
Linear And Nonlinear ◽  
Gnss Network ◽  
Global Navigation Satellite ◽  
Gnss Data

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.

scholarly journals New GNSS tomography of the atmosphere method – proposal and testing

2012 ◽  
Vol 9 ◽  
pp. 63-76 ◽  
Author(s):  
Michal Kačmařík ◽  
Lukáš Rapant
Keyword(s):  
Water Vapour ◽  
Theoretical Concept ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Gnss Meteorology ◽  
Gnss Receivers ◽  
Tomography Method ◽  
Gnss Measurements ◽  
Global Navigation Satellite

Paper is focused on GNSS meteorology which is generally used for the determination of water vapour distribution in the atmosphere from GNSS measurements. Water vapour in the atmosphere is an important parameter which influences the state and development of the weather. At first, the paper presents basics of the GNSS meteorology and tomography of the atmosphere and subsequently introduces a new GNSS tomography method which doesn't require an extensive network of GNSS receivers, but uses only a few receivers situated in a line. After a theoretical concept describing this method and used mathematical background, the results from a real experiment are shown and discussed. Unfortunately the results indicate that presented method is not able to provide credible outputs. Possibly the main problem lies in an insufficient number of available signals from current global navigation satellite systems (GPS and GLONASS) where the improvement could be expected after the start of Galileo and Compass. Potential ways how to improve the results without increasing the number of satellites are outlined in the last section.

scholarly journals THE HANDHELD MOBILE LASER SCANNERS AS A TOOL FOR ACCURATE POSITIONING UNDER FOREST CANOPY

2020 ◽  
Vol XLIII-B1-2020 ◽  
pp. 211-218 ◽  
Author(s):  
J. Chudá ◽  
M. Hunčaga ◽  
J. Tuček ◽  
M. Mokroš
Keyword(s):  
Forest Canopy ◽  
Sustainable Forest Management ◽  
Environmental Data ◽  
Global Navigation Satellite Systems ◽  
Forest Environment ◽  
Positional Accuracy ◽  
Satellite Systems ◽  
Localization And Mapping ◽  
Laser Scanners ◽  
Global Navigation Satellite

Abstract. Nowadays it is important to shift positional accuracy of object measurements under the forest canopy closer to the accuracy standards for land surveys due to the requirements in the field of ecosystem protection, sustainable forest management, property relations, and land register. Simultaneously, it is desirable to use the technology of environmental data acquisition which is not time consuming and cost demanding. Global Navigation Satellite Systems (GNSS) are the most used for positioning today. However, the usefulness and also the accuracy of the measurements with this technology depend on various factors (the strength of the GNSS signal, the geometric position of satellites, the multipath effect etc.). Based on the above mentioned facts, the usability of technology independent of GNSS indicates an ideal solution for positioning under the forest canopy. Several studies have studied the usability of Handheld Mobile Laser Scanners (HMLS) in complex environment. The goal of this paper was to verify a new data collection approach (HMLS with Simultaneous Localization and Mapping (SLAM) technology) for the forest environment practice. The main objective of our study was to reach a precision which complies with the accuracy standards for land surveys. The RMSE of derived positions from point cloud, produced by SLAM devices were 25.3 cm and 28.4 cm, for ZEB REVO and ZEB HORIZON, the handheld mobile laser SLAM scanners used in this study. ZEB HORIZON achieved twice as big accuracy of diameter of breast height (DBH) estimation as ZEB REVO.

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

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>

Assessment of geodetic products from MGEX analyses for the Onsala site

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>

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

2017 ◽  
Vol 35 (3) ◽  
pp. 377-391 ◽  
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.

scholarly journals Determination of orthometric elevations using gnss-derived height with the egm2008 geoid height model

2017 ◽  
Vol 5 (1) ◽  
pp. 13
Author(s):  
Emmanuel Menegbo
Keyword(s):  
Geoid Height ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Maximum Elevation ◽  
Gis Data ◽  
Gnss Receivers ◽  
Orthometric Heights ◽  
Global Navigation Satellite ◽  
The Relationship

The Global navigation satellite systems (GNSS) has imparted positively on civilian positioning & surveying in the horizontal component in Nigeria for the past two decades. The GNSS receivers’ data are longitude, latitude & elevation. However, the vertical distance measurement have not been fully exploited by geodetic and land surveyors. The GNSS derived heights are ellipsoidal elevation. To convert the GNSS elevation to orthometric heights, a geoidal elevation models is needed. The Earth Gravitational Model, 2008 (EGM2008) is a global geoidal models that can be used to obtain GNSS orthometric heights by defining the relationship with the ellipsoid. This work determines GNSS-derived orthometric heights with ellipsoid-geoidal relationship using GPS ellipsoidal heights and EGM2008 geoidal model GIS data. The EGM2008 GIS data was downloaded and interpolated with GPS data to obtain geoidal heights using ArcGIS 10.1. GNSS-derived heights determined with geoid-ellipsoid relationship formula. The result shows minimum elevation of -2.37599m and maximum elevation of 53.8566m.The derived orthometric heights use to create a model in raster format. The orthometric elevation models created useful in all vertical surveying work, construction work and urban planning. The GNSS orthometric heights models need to be compare with spirit levelling and the local geoidal model determined for improve accuracy.

scholarly journals A Tunable and Electrically Small Antenna for Compact GNSS Receivers

2021 ◽  
Vol 13 (3) ◽  
pp. 485
Author(s):  
Yevhen Yashchyshyn ◽  
Dmytro Vynnyk ◽  
Volodymyr Haiduchok ◽  
Ivan Solskii ◽  
Changying Wu ◽  
...  
Keyword(s):  
Electronic Devices ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Electrically Small Antenna ◽  
Half Wavelength ◽  
Gnss Receivers ◽  
Operational Frequency ◽  
Small Antenna ◽  
Global Navigation Satellite ◽  
Handheld Electronic Devices

The electronic receivers of global navigation satellite systems (GNSSs) are implemented in various handheld electronic devices such as laptops, smartphones, and smartwatches; therefore, their dimensions are of critical importance. Achieving a GNSS terminal of a small size is difficult due to its relatively low operational frequency (L-band), which is equivalent to a wavelength of approximately 24 cm. As an efficient half-wavelength antenna is too large for compact devices, in this paper, an electrically small antenna (ESA) for GNSS terminals is presented. The antenna was miniaturized by using a dielectric block with relatively high permittivity, making some parts virtual, and optimizing its geometry. The operational frequency of the ESA is tunable by means of metallic rods of variable heights inserted into a cylindrical cavity drilled inside the dielectric block. The results confirm the feasibility of the concept and the usability of the ESA for compact GNSS terminals.

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