EXPERIMENTAL RESEARCH OF THE ACCURACY OF NAVIGATION GNSS - RECEIVERS IN CONDITIONS OF THE CONSTRUCTED TERRITORY

Use of digital geodetic support technologies with the use of GNSS satellite systems in combination with electronic geodetic instruments, introduction of new methods of construction of geodetic networks, collection of information by ground and aerospace surveying, unification of exchange formats of measurement results based on computer technologies and their application conditions. Substantiation and development of remote methods of spatial information collection requires analysis and consideration of a number of errors in order to improve accuracy. Wikimapia is a map project for shared use with open content, which aims to identify all geographical objects with the introduction of useful information about them. It combines an interactive web map and a Wiki system. One of the features of the Wikimapia resource is that it is possible to determine geographical coordinates. To do this, you need to move the cross cursor on the object of interest and get its coordinates visually. The purpose of the study was to determine the accuracy of the coordinates of GPS receivers Garmin Oregon 450 in the built-up area, using as a basis for calibration, the resource "Wikimapia". In order to determine the accuracy of the location with the help of GARMIN Oregon 450 GPS receivers, GNSS measurements were performed at 30 marker points. Ellipsoidal coordinates were recalculated into spatial rectangles according to known formulas. In order to assess the accuracy of determining the location of marker points, the differences in the coordinates of their position were found and the root mean square error from a number of measurements was found. The average error of coordinate measurements was ± 4.79 m for the GPS receiver. Based on experimental research, the possibility of using the resource "Wikimapia" not only to quickly determine the coordinates of topographic objects, determine their categories, but also with sufficient accuracy to apply for the calibration of navigation GNSS receivers when there is no network of geodetic points. A promising direction in the process of scientific and practical research should be the creation of a general mathematical model for predicting the influence of the plurality on the location and improvement of navigation aids.

Download Full-text

New GNSS tomography of the atmosphere method – proposal and testing

Geoinformatics FCE CTU ◽

10.14311/gi.9.6 ◽

2012 ◽

Vol 9 ◽

pp. 63-76 ◽

Cited By ~ 1

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.

Download Full-text

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.

Download Full-text

Assessing the quality of GEOID12B model through field surveys

Journal of Applied Geodesy ◽

10.1515/jag-2017-0013 ◽

2018 ◽

Vol 12 (1) ◽

pp. 1-13

Author(s):

Ahmed Elaksher ◽

Franck Kamtchang ◽

Christian Wegmann ◽

Adalberto Guerrero

Keyword(s):

Geoid Undulation ◽

Kriging Model ◽

Random Errors ◽

Dual Frequency ◽

Field Surveys ◽

Satellite Systems ◽

Gnss Receivers ◽

Orthometric Heights ◽

Geoid Undulations

AbstractElevation differences have been determined through conventional ground surveying techniques for over a century. Since the mid-80s GPS, GLONASS and other satellite systems have modernized the means by which elevation differences are observed. In this article, we assessed the quality of GEIOD12B through long-occupation GNSS static surveys. A set of NGS benchmarks was occupied for at least one hour using dual-frequency GNSS receivers. Collected measurements were processed using a single CORS station at most 24 kilometers from the benchmarks. Geoid undulation values were driven by subtracting measured ellipsoidal heights from the orthometric heights posted on the NGS website. To assess the quality of GEOID12B, we compared our computed vertical shifts at the benchmarks with those estimated from GEOID12B published by NGS. In addition, Kriging model was used to interpolate local maps for the geoid undulations from the benchmark heights. The maps were compared with corresponding parts of GEOID12B. No biases were detected in the results and only shifts due to random errors were found. Discrepancies in the range of ten centimetres were noticed between our geoid undulation and the values available from NGS.

Download Full-text

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

Download Full-text

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 ◽

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.

Download Full-text

An Examination of Five Identical Mapping-Grade Global Positioning System Receivers in Two Forest Settings

Western Journal of Applied Forestry ◽

10.1093/wjaf/26.3.119 ◽

2011 ◽

Vol 26 (3) ◽

pp. 119-125 ◽

Cited By ~ 5

Author(s):

Michael G. Wing ◽

Jereme Frank

Keyword(s):

Measurement Errors ◽

Primary Objective ◽

Average Error ◽

Gps Receivers ◽

Young Forest ◽

Significant Difference ◽

Secondary Objective ◽

Satellite Signal ◽

Sky Conditions ◽

Identical Mapping

Abstract We collected measurements using five identical high-quality mapping-grade GPS receivers that were configured the same and collected data simultaneously in two distinctly different settings within a forest. Our primary objective was to determine whether measurement accuracies were different among the mapping-grade GPS receivers. A secondary objective was to determine whether measurement accuracies were different depending on whether receivers established their locations by taking a single 1-second measurement or by averaging 30 or 60 measurements. In the open-sky setting, where receivers had few obstructions overhead, we found that all five receivers recorded measurements with similar positional accuracies. Errors were lower when measurements were differentially corrected (postprocessed). We found an average error of 1.6 m for unprocessed data and an average error of 0.2 m for postprocessed data. Our results indicate that in open-sky conditions, all five receivers performed similarly when measurements were postprocessed. In addition, there was no significant difference in accuracy whether 1, 30, or 60 points were averaged, regardless of whether data were postprocessed. In the young-forest test course, examination of errors between receivers revealed that one receiver had significantly different errors compared with other receivers, which was likely the result of environmental influences on satellite signal strength and availability. We also found that measurement errors for all five receivers were significantly lower when measurements were postprocessed. On average, measurement errors were 5.9 m for unprocessed data and 1.4 m for postprocessed data. In analyzing individual receiver errors, no receiver had significantly different measurement errors whether 1, 30, or 60 measurements were recorded.

Download Full-text

Precise Point Positioning using Multi-Constellation GNSS Observations for Kinematic Applications

Journal of Applied Geodesy ◽

10.1515/jag-2014-0021 ◽

2015 ◽

Vol 9 (1) ◽

Cited By ~ 12

Author(s):

Mahmoud Abd Rabbou ◽

Ahmed El-Rabbany

Keyword(s):

Urban Areas ◽

Precise Point Positioning ◽

Global Navigation Satellite Systems ◽

Test Scenario ◽

Satellite Systems ◽

Satellite Geometry ◽

Point Positioning ◽

Kinematic Ppp ◽

Gnss Measurements ◽

Global Navigation Satellite

AbstractTraditional precise point positioning (PPP) is commonly based on un-differenced ionosphere-free linear combination of Global Positioning System (GPS) observations. Unfortunately, for kinematic applications, GPS often experiences poor satellite visibility or weak satellite geometry in urban areas. To overcome this limitation, we developed a PPP model, which combines the observations of three global navigation satellite systems (GNSS), namely GPS, GLONASS and Galileo. Both un-differenced and between-satellite single-difference (BSSD) ionosphere-free linear combinations of pseudorange and carrier phase GNSS measurements are processed. The performance of the combined GNSS PPP solution is compared with the GPS-only PPP solution using a real test scenario in downtown Kingston, Ontario. Inter-system biases between GPS and the other two systems are also studied and obtained as a byproduct of the PPP solution. It is shown that the addition of GLONASS observations improves the kinematic PPP solution accuracy in comparison with that of GPS-only solution. However, the contribution of adding Galileo observations is not significant due to the limited number of Galileo satellites launched up to date. In addition, BSSD solution is found to be superior to that of traditional un-differenced model.

Download Full-text

A New High-Resolution GPS Multipath Mitigation Technique Using Fast Orthogonal Search

Journal of Navigation ◽

10.1017/s0373463315001022 ◽

2016 ◽

Vol 69 (4) ◽

pp. 794-814 ◽

Cited By ~ 10

Author(s):

Mohamed Tamazin ◽

Aboelmagd Noureldin ◽

Michael J. Korenberg ◽

Ahmed M. Kamel

Keyword(s):

High Resolution ◽

Global Navigation Satellite Systems ◽

Multipath Mitigation ◽

Gps Receivers ◽

Satellite Systems ◽

Delay Locked Loop ◽

Orthogonal Search ◽

Fast Orthogonal Search ◽

Global Navigation Satellite ◽

Mitigation Technique

The Delay Locked Loop (DLL) tracking algorithm is one of the most widely used in GPS receivers. It uses different correlators such as the Early-Late Slope (ELS) correlator and High-Resolution Correlator (HRC) to mitigate code phase multipath. These techniques are effective for weak multipath environments but they may not be suitable for challenging multipath environments. The Multipath Estimating Delay Lock Loop (MEDLL) shows better performance than the classical methods. However, MEDLL still has limited capabilities in severe multipath environments. This paper introduces a robust multipath mitigation technique based on fast orthogonal search to obtain better delay estimation for GPS receivers. This research utilised a SPIRENT Global Navigation Satellite Systems (GNSS) simulator to compare the performance of the proposed method with other multipath mitigation techniques. Experimental results demonstrated that the performance of the proposed algorithm was better than the classical and advanced techniques under the multipath scenarios tested.

Download Full-text

Experimental Assessment of UWB and Vision-Based Car Cooperative Positioning System

Remote Sensing ◽

10.3390/rs13234858 ◽

2021 ◽

Vol 13 (23) ◽

pp. 4858

Author(s):

Andrea Masiero ◽

Charles Toth ◽

Jelena Gabela ◽

Guenther Retscher ◽

Allison Kealy ◽

...

Keyword(s):

Essential Element ◽

Wide Band ◽

Global Navigation Satellite Systems ◽

Learning Tools ◽

Satellite Systems ◽

Cooperative Positioning ◽

Performance Improvements ◽

Gnss Measurements ◽

Global Navigation Satellite ◽

Gnss Data

The availability of global navigation satellite systems (GNSS) on consumer devices has caused a dramatic change in every-day life and human behaviour globally. Although GNSS generally performs well outdoors, unavailability, intentional and unintentional threats, and reliability issues still remain. This has motivated the deployment of other complementary sensors in such a way that enables reliable positioning, even in GNSS-challenged environments. Besides sensor integration on a single platform to remedy the lack of GNSS, data sharing between platforms, such as in collaborative positioning, offers further performance improvements for positioning. An essential element of this approach is the availability of internode measurements, which brings in the strength of a geometric network. There are many sensors that can support ranging between platforms, such as LiDAR, camera, radar, and many RF technologies, including UWB, LoRA, 5G, etc. In this paper, to demonstrate the potential of the collaborative positioning technique, we use ultra-wide band (UWB) transceivers and vision data to compensate for the unavailability of GNSS in a terrestrial vehicle urban scenario. In particular, a cooperative positioning approach exploiting both vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) UWB measurements have been developed and tested in an experiment involving four cars. The results show that UWB ranging can be effectively used to determine distances between vehicles (at sub-meter level), and their relative positions, especially when vision data or a sufficient number of V2V ranges are available. The presence of NLOS observations is one of the principal factors causing a decrease in the UWB ranging performance, but modern machine learning tools have shown to be effective in partially eliminating NLOS observations. According to the obtained results, UWB V2I can achieve sub-meter level of accuracy in 2D positioning when GNSS is not available. Combining UWB V2I and GNSS as well V2V ranging may lead to similar results in cooperative positioning. Absolute cooperative positioning of a group of vehicles requires stable V2V ranging and that a certain number of vehicles in the group are provided with V2I ranging data. Results show that meter-level accuracy is achieved when at least two vehicles in the network have V2I data or reliable GNSS measurements, and usually when vehicles lack V2I data but receive V2V ranging to 2–3 vehicles. These working conditions typically ensure the robustness of the solution against undefined rotations. The integration of UWB with vision led to relative positioning results at sub-meter level of accuracy, an improvement of the absolute positioning cooperative results, and a reduction in the number of vehicles required to be provided with V2I or GNSS data to one.

Download Full-text

GEODESIC METHODS FOR CREATION OF UNIQUE GEOINFORMATION SPACE

Interexpo GEO-Siberia ◽

10.33764/2618-981x-2019-1-1-173-183 ◽

2019 ◽

Vol 1 (1) ◽

pp. 173-183

Author(s):

Sergey Gorobtsov ◽

Vladimir Obidenko

Keyword(s):

Laser Scanning ◽

Spatial Information ◽

Survey Methods ◽

Essential Element ◽

Global Navigation Satellite Systems ◽

3D Laser Scanning ◽

Foreign Markets ◽

Satellite Systems ◽

Ground Survey ◽

Global Navigation Satellite

Modern geodesic support is an integral and essential element of the process of collecting spatial information. The article considers geodesic methods for creating a unique geoinformation space: digitization of cartographic materials, ground survey methods (electronic total stations, 3D laser scanning), remote sensing and methods of the global navigation satellite systems GLONASS and GPS. The article also contains recommended conversion options between the coordinate systems SK-95 and GSK-2011. A comparative analysis of the surveyed geodesic methods for geodata col-lection was carried out. Russian and foreign markets of specialized software for processing geodata are considered, appropriate conclusions are made.

Download Full-text