Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: GNSS Techniques.
Artykuły w czasopismach na temat „GNSS Techniques”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych artykułów w czasopismach naukowych na temat „GNSS Techniques”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj artykuły w czasopismach z różnych dziedzin i twórz odpowiednie bibliografie.
1
Zubinaitė, Vilma, i George Preiss. "A PROPOSED SIMPLIFIED TECHNIQUE FOR CONFIRMING HIGH PRECISION GNSS ANTENNA OFFSETS". Aviation 14, nr 3 (30.09.2010): 83–89. http://dx.doi.org/10.3846/aviation.2010.13.
Pełny tekst źródłaStreszczenie:
The purpose of this research was to independently investigate and determine confirmatory calibration procedures for GNSS antennas. This paper focuses on the aspect of simplified techniques for confirming high precision GNSS antenna offsets. In the other words, the aim is to verify GNSS antenna offset parameters ‐ results, which will be used to find the consequences on ground positions of orbital distortions caused by solar activity. It is well known that the computation of GNSS observations using high precision GNSS antennas requires knowledge of the relevant antenna phase centre offsets. These offsets are the distance in three dimensions from the antenna's physical centre to the point in space at which the antenna ‘measures’ position. The calibration processes used by manufacturers appear to vary, and, where receivers of different models are to be used together, it is essential that the calibration parameters used are all produced using the same methods and by the same authoritative sources. Meanwhile, with the growth in the use of high precision GNSS systems, the likelihood of antennas being accidentally mishandled is possibly higher than previously. Finally, it is noted that it has long been the practise for surveyors to check their instruments to ensure that they are properly calibrated. In the modern electronic age, however, it seems that this practise has been allowed to lapse as far as GNSS instrumentation is concerned. With the above in mind, it has been decided to attempt to create a simplified procedure for calibrating high precision GNSS antennas. The aim is that it will be possible for the average surveyor to check his antenna without great effort or trouble. The objective can also be described as finding a simplified field procedure to determine whether a specific antenna's offset parameters are within reasonable agreement with published figures. Santrauka Straipsnyje analizuojamas supaprastintas metodas, kuriuo galima aprobuoti aukšto tikslumo globalines navigacines palydovines sistemos (GNPS) antenos nukrypimus. Siekiama patinkrinti GNPS antenos nukrypimo parametrus ‐ rezultatus, kurie bus naudojami nustatant GNPS palydovo orbitos iškraipymu padarinius. Nagrinejama procedūra, kai siekiama nustatyti, ar konkrečios GNPS antenos kalibravimo parametrai yra pagristi, palyginti su publikuotais duomenimis. Analizuojama problema yra aktuali, kai GNPS matavimams naudojamos aukšto tikslumo GNPS antenos ir reikalingos žinios, susijusios su antenos fazes centro nukrypimais.
2
Qiu, Tongsheng, Xianyi Wang, Yueqiang Sun, Fu Li, Zhuoyan Wang, Junming Xia, Qifei Du i in. "An Innovative Signal Processing Scheme for Spaceborne Integrated GNSS Remote Sensors". Remote Sensing 15, nr 3 (27.01.2023): 745. http://dx.doi.org/10.3390/rs15030745.
Pełny tekst źródłaStreszczenie:
The vigorous development of the global navigation satellite system (GNSS) has led to a boom in GNSS radio occultation (GNSS RO) and GNSS reflectometry (GNSS-R) techniques. Consequently, we have proposed an innovative signal processing scheme for spaceborne integrated GNSS remote sensors (SIGRS), combining a GNSS RO and a GNSS-R module. In the SIGRS, the GNSS-R module shares one precise orbit determination (POD) module with the GNSS RO module, and the GNSS-R module first achieves compatibility with GPS, BDS, and Galileo. Moreover, the programmable non-uniform delay resolution was introduced and first used by the SIGRS to generate the output DDM, which achieves a high delay resolution in the DDM central region around the specular point to improve the accuracy of basic observables but requires fewer delay bins than the conventional DDM with uniform delay resolution. The SIGRS has been successfully used to design the GNOS II onboard the Chinese FY-3E satellite, and the results of in-orbit operation validate the performance of the SIGRS, which means the SIGRS is an economically and technically efficient design and has become the first successful signal processing scheme for spaceborne integrated GNSS remote sensors around the world.
3
Kim, Hanjin, Chang-Uk Hyun, Hyeong-Dong Park i Jongmun Cha. "Image Mapping Accuracy Evaluation Using UAV with Standalone, Differential (RTK), and PPP GNSS Positioning Techniques in an Abandoned Mine Site". Sensors 23, nr 13 (24.06.2023): 5858. http://dx.doi.org/10.3390/s23135858.
Pełny tekst źródłaStreszczenie:
Global navigation satellite systems (GNSSs) provide a common positioning method that utilizes satellite signals to determine the spatial location of a receiver. However, there are several error factors in standalone GNSS positioning due to instrumental, procedural, and environmental factors that arise during the signal transmission process, and the final positioning error can be up to several meters or greater in length. Thus, real-time kinematic (RTK) correction and post-mission precise point positioning (PPP) processing technologies are proposed to improve accuracy and accomplish precise position measurements. To evaluate the geolocation accuracy of mosaicked UAV images of an abandoned mine site, we compared each orthomosaic image and digital elevation model obtained using standalone GNSS positioning, differential (RTK) GNSS positioning, and post-mission PPP processing techniques. In the three types of error evaluation measure (i.e., relative camera location error, ground control points-based absolute image mapping error, and volumetric difference of mine tailings), we found that the RTK GNSS positioning method obtained the best performance in terms of the relative camera location error and the absolute image mapping error evaluations, and the PPP post-processing correction effectively reduced the error (69.5% of the average total relative camera location error and 59.3% of the average total absolute image mapping error) relative to the standalone GNSS positioning method. Although differential (RTK) GNSS positioning is widely used in positioning applications that require very high accuracy, post-mission PPP processing can also be used in various fields in which it is either not feasible to operate expensive equipment to receive RTK GNSS signals or network RTK services are unavailable.
4
Guerova, Guergana, Jonathan Jones, Jan Douša, Galina Dick, Siebren de Haan, Eric Pottiaux, Olivier Bock i in. "Review of the state of the art and future prospects of the ground-based GNSS meteorology in Europe". Atmospheric Measurement Techniques 9, nr 11 (8.11.2016): 5385–406. http://dx.doi.org/10.5194/amt-9-5385-2016.
Pełny tekst źródłaStreszczenie:
Abstract. Global navigation satellite systems (GNSSs) have revolutionised positioning, navigation, and timing, becoming a common part of our everyday life. Aside from these well-known civilian and commercial applications, GNSS is now an established atmospheric observing system, which can accurately sense water vapour, the most abundant greenhouse gas, accounting for 60–70 % of atmospheric warming. In Europe, the application of GNSS in meteorology started roughly two decades ago, and today it is a well-established field in both research and operation. This review covers the state of the art in GNSS meteorology in Europe. The advances in GNSS processing for derivation of tropospheric products, application of GNSS tropospheric products in operational weather prediction and application of GNSS tropospheric products for climate monitoring are discussed. The GNSS processing techniques and tropospheric products are reviewed. A summary of the use of the products for validation and impact studies with operational numerical weather prediction (NWP) models as well as very short weather prediction (nowcasting) case studies is given. Climate research with GNSSs is an emerging field of research, but the studies so far have been limited to comparison with climate models and derivation of trends. More than 15 years of GNSS meteorology in Europe has already achieved outstanding cooperation between the atmospheric and geodetic communities. It is now feasible to develop next-generation GNSS tropospheric products and applications that can enhance the quality of weather forecasts and climate monitoring. This work is carried out within COST Action ES1206 advanced global navigation satellite systems tropospheric products for monitoring severe weather events and climate (GNSS4SWEC, http://gnss4swec.knmi.nl).
5
Abd el rahman, Mustafa, Mohamed elharmel, Roshdy Abdelrasol, Mohamed Zagloul i Mohamed elghamry. "GNSS Interference Suppression Techniques: A Survey". International Journal of Telecommunications 01, nr 01 (18.12.2021): 1–10. http://dx.doi.org/10.21608/ijt.2021.266285.
Pełny tekst źródła
6
Szmagliński, Jacek, Andrzej Wilk, Władysław Koc, Krzysztof Karwowski, Piotr Chrostowski, Jacek Skibicki, Sławomir Grulkowski i in. "Verification of Satellite Railway Track Position Measurements Making Use of Standard Coordinate Determination Techniques". Remote Sensing 14, nr 8 (12.04.2022): 1855. http://dx.doi.org/10.3390/rs14081855.
Pełny tekst źródłaStreszczenie:
The article presents the results of satellite railway track position measurements performed by a multidisciplinary research team, the members of which represented Gdansk University of Technology and Gdynia Maritime University. Measuring methods are described which were used for reconstructing the railway track axis position and diagnosing railway track geometry deformations. As well as that, the description of the novel method developed by the authors to perform mobile GNSS measurements is included. The reported research aimed at assessing the uncertainty of railway track axis reconstruction making use of the dynamic GNSS method. To assess the applicability of this method, the obtained results were compared with those from the stationary measurement method used in railway business. The data used for comparison was recorded on the same railway track section during several measurement campaigns. In these campaigns, different types of GNSSs with different position recording frequencies (1–100 Hz) were used at different measurement speeds (5–70 km/h). The performed analysis has shown that the accuracy of railway track axis reconstruction making use of mobile GNSS measurements is sufficient for using this methodology in railway business.
7
Liu, Congliang, Yueqiang Sun, Weihua Bai, Qifei Du, Wei Li, Xi Wang i Peixian Li. "Effect of Multiple GNSS Integration on the Number and Spatiotemporal Coverage of Radio Occultation Events". Atmosphere 13, nr 5 (20.04.2022): 654. http://dx.doi.org/10.3390/atmos13050654.
Pełny tekst źródłaStreszczenie:
The development of global navigation satellite systems (GNSSs) and multi-system compatible radio occultation (RO) techniques provides favorable conditions and opportunities for increasing the number of occultation events and improving their spatiotemporal coverage. The performance of the multiple GNSS RO event number, spatiotemporal coverage, and uniformity need assessments by robust and functional approaches. Firstly, a simulation system of RO events, which took the orbit perturbations into account, was established, and the concepts of global coverage fraction and uniformity of RO events were defined. Secondly, numerical experiments were designed to analyze the GNSS RO performances of a single-receiving satellite and satellite constellations under the condition of using current multiple GNSSs as transmitting satellite systems, in which the Earth was divided into 400 × 400 km2 grids. Finally, the number, timeliness, global coverage fraction, and uniformity of GNSS RO events for a single-receiving satellite and receiving satellite constellations were numerically calculated and analyzed. The results showed that ➀ multiple GNSS integration improved the number of GNSS RO events and their global coverage for a single polar-orbit satellite significantly, e.g., the 24 h multiple GNSS RO event number was about 7.8 times that of the single GNSS system, BeiDou navigation satellite system-3, while the corresponding 24 h global coverage fraction increased nearly 3 times. ➁ In the multiple GNSS integration scenario, the constellation composed of 12 polar-orbit low-Earth-orbit satellites achieved 100% RO event global coverage fraction within 24 h, of which the RO detection capability was comparable to the 100 Spire weather satellites and global positioning system (GPS) RO system. ➂ More GNSS RO events of the polar-orbit constellations were distributed in the middle- and high-latitude zones. Therefore, multiple GNSS integration could increase the RO event number and global coverage significantly to benefit the global climate monitoring and global numerical weather prediction, and the polar-orbit constellations were more favorable to atmospheric detection in middle- and high-latitude regions.
8
Farolfi, Gregorio, Aldo Piombino i Filippo Catani. "Fusion of GNSS and Satellite Radar Interferometry: Determination of 3D Fine-Scale Map of Present-Day Surface Displacements in Italy as Expressions of Geodynamic Processes". Remote Sensing 11, nr 4 (15.02.2019): 394. http://dx.doi.org/10.3390/rs11040394.
Pełny tekst źródłaStreszczenie:
We present a detailed map of ground movement in Italy derived from the combination of the Global Navigation Satellite System (GNSS) and Satellite Synthetic Aperture Radar (SAR) interferometry. These techniques are two of the most used space geodetic techniques to study Earth surface deformation. The above techniques provide displacements with respect to different components of the ground point position; GNSSs use the geocentric International Terrestrial Reference System 1989 (ITRS89), whereas the satellite SAR interferometry components are identified by the Lines of Sight (LOSs) between a satellite and ground points. Moreover, SAR interferometry is a differential technique, and for that reason, displacements have no absolute reference datum. We performed datum alignment of InSAR products using precise velocity fields derived from GNSS permanent stations. The result is a coherent ground velocity field with detailed boundaries of velocity patterns that provide new information about the complex geodynamics involved on the Italian peninsula and about local movements.
9
Jin, Shuanggen, Qisheng Wang i Gino Dardanelli. "A Review on Multi-GNSS for Earth Observation and Emerging Applications". Remote Sensing 14, nr 16 (13.08.2022): 3930. http://dx.doi.org/10.3390/rs14163930.
Pełny tekst źródłaStreszczenie:
Global Navigation Satellite System (GNSS) has drawn the attention of scientists and users all over the world for its wide-ranging Earth observations and applications. Since the end of May 2022, more than 130 satellites are available for fully global operational satellite navigation systems, such as BeiDou Navigation Satellite System (BDS), Galileo, GLONASS and GPS, which have been widely used in positioning, navigation, and timing (PNT), e.g., precise orbit determination and location-based services. Recently, the refracted, reflected, and scattered signals from GNSS can remotely sense the Earth’s surface and atmosphere with potential applications in environmental remote sensing. In this paper, a review of multi-GNSS for Earth Observation and emerging application progress is presented, including GNSS positioning and orbiting, GNSS meteorology, GNSS ionosphere and space weather, GNSS-Reflectometry and GNSS earthquake monitoring, as well as GNSS integrated techniques for land and structural health monitoring. One of the most significant findings from this review is that, nowadays, GNSS is one of the best techniques in the field of Earth observation, not only for traditional positioning applications, but also for integrated remote sensing applications. With continuous improvements and developments in terms of performance, availability, modernization, and hybridizing, multi-GNSS will become a milestone for Earth observations and future applications.
10
Alonso, Maria Teresa, Carlo Ferigato, Deimos Ibanez Segura, Domenico Perrotta, Adria Rovira-Garcia i Emmanuele Sordini. "Analysis of ‘Pre-Fit’ Datasets of gLAB by Robust Statistical Techniques". Stats 4, nr 2 (24.05.2021): 400–418. http://dx.doi.org/10.3390/stats4020026.
Pełny tekst źródłaStreszczenie:
The GNSS LABoratory tool (gLAB) is an interactive educational suite of applications for processing data from the Global Navigation Satellite System (GNSS). gLAB is composed of several data analysis modules that compute the solution of the problem of determining a position by means of GNSS measurements. The present work aimed to improve the pre-fit outlier detection function of gLAB since outliers, if undetected, deteriorate the obtained position coordinates. The methodology exploits robust statistical tools for regression provided by the Flexible Statistics and Data Analysis (FSDA) toolbox, an extension of MATLAB for the analysis of complex datasets. Our results show how the robust analysis FSDA technique improves the capability of detecting actual outliers in GNSS measurements, with respect to the present gLAB pre-fit outlier detection function. This study concludes that robust statistical analysis techniques, when applied to the pre-fit layer of gLAB, improve the overall reliability and accuracy of the positioning solution.
11
Boguspayev, Nurlan, Daulet Akhmedov, Almat Raskaliyev, Alexandr Kim i Anna Sukhenko. "A Comprehensive Review of GNSS/INS Integration Techniques for Land and Air Vehicle Applications". Applied Sciences 13, nr 8 (12.04.2023): 4819. http://dx.doi.org/10.3390/app13084819.
Pełny tekst źródłaStreszczenie:
Navigation systems are of interest for applications in both civilian and military vehicles. Satellite navigation systems and inertial navigation systems are the most applied in this area. They have complementary properties, which has led to a trend of integrating these systems. At present, there are several approaches to GNSS/INS integration: loosely coupled, tightly coupled and deeply coupled and many approaches to their modifications in dependence of application and arising problems with measurements, such as lack of GNSS measurements or poor quality of GNSS and INS measurements. This article presents an extensive review of the available modern approaches and their modifications for integrating INS and GNSS measurements, arranging them and highlights the main problems arising for the considered type of integration approach. The article includes a review of various integration tools based on the Kalman filter and intelligent systems, INS mechanization and features of development of an INS measurement error model that is necessary for integration, the main problems of GNSS/INS integration and a comparative description of the solutions proposed by the authors for solving these problems. The findings of this work are useful for further research in the field of inertial and satellite navigation, as well as for engineers involved in the practical implementation of integrated GNSS/INS systems.
12
Barba, Paola, Belén Rosado, Javier Ramírez-Zelaya i Manuel Berrocoso. "Comparative Analysis of Statistical and Analytical Techniques for the Study of GNSS Geodetic Time Series". Engineering Proceedings 5, nr 1 (28.06.2021): 21. http://dx.doi.org/10.3390/engproc2021005021.
Pełny tekst źródłaStreszczenie:
GNSS systems allow precise resolution of the geodetic positioning problem through advanced techniques of GNSS observation processing (PPP or relative positioning). Current instrumentation and communications capabilities allow obtaining geocentric and topocentric geodetic high frequencies time series, whose analysis provides knowledge of the tectonic or volcanic geodynamic activity of a region. In this work, the GNSS time series study was carried out through the use and adaptation of R packets to determine their behavior, obtaining displacement velocities, noise levels, precursors in the time series, anomalous episodes, and their temporal forecast. Statistical and analytical methods were studied, for example, ARMA, ARIMA models, least-squares methods, wavelet functions, and Kalman techniques. To carry out a comparative analysis of these techniques and methods, significant GNSS time series obtained in geodynamically active regions (tectonic and/or volcanic) were considered.
13
Kalayci, Ibrahim, i Sermet Ogutcu. "A novel approach for detail surveys by the motorized GPSSIT concept in residentials areas and its application". Boletim de Ciências Geodésicas 20, nr 1 (marzec 2014): 70–83. http://dx.doi.org/10.1590/s1982-21702014000100005.
Pełny tekst źródłaStreszczenie:
This paper introduces the usage and reliability of Motorized GPSSIT technique which is a novel approach for surveying. It reviews the advantages of Motorized GPSSIT concept and also considers to provide GNSS accuracy in the process of surveying especially for the cases which cannot be surveyed directly by the satellite navigation systems (GPS-GNSS), such as closely packed residential areas, tall buildings, trees, etc., and also places which GNSS receivers cannot be work efficiently due to signal interferences. In this technique, all the survey instruments are installed on a bed of a pick-up truck whereas in present techniques they are installed on the ground, therefore it is called Motorized GPSSIT. Study area was chosen within the housing area of our campus. In this area, classical surveying, GPSSIT and Motorized GPSSIT were performed to collect data for comparison and for the analysis of this technique's usability and reliability. Stop and Go and RTK surveying techniques were performed with GPSSIT and Motorized GPSSIT concepts. It is shown that the Motorized GPSSIT technique is applicable as other present techniques in terms of accuracy and reliability.
14
Manito, João, i José Sanguino. "Performance Evaluation of GPS Auto-Surveying Techniques". Sensors 21, nr 21 (6.11.2021): 7374. http://dx.doi.org/10.3390/s21217374.
Pełny tekst źródłaStreszczenie:
With the increase in the widespread use of Global Navigation Satellite Systems (GNSS), increasing numbers of applications require precise position data. Of all the GNSS positioning methods, the most precise are those that are based in differential systems, such as Differential GNSS (DGNSS) and Real-Time Kinematics (RTK). However, for absolute positioning, the precision of these methods is tied to their reference position estimates. With the goal of quickly auto-surveying the position of a base station receiver, four positioning methods are analyzed and compared, namely Least Squares (LS), Weighted Least Squares (WLS), Extended Kalman Filter (EKF) and Unscented Kalman Filter (UKF), using only pseudorange measurements, as well as the Hatch Filter and position thresholding. The research results show that the EKF and UKF present much better mean errors than LS and WLS, with an attained precision below 1 m after about 4 h of auto-surveying. The methods that presented the best results are then tested against existing implementations, showing them to be very competitive, especially considering the differences between the used receivers. Finally, these results are used in a DGNSS test, which verifies a significant improvement in the position estimate as the base station position estimate improves.
15
Wang, Wenbo, Ignacio Aguilar Sanchez, Gianluca Caparra, Andy McKeown, Tim Whitworth i Elena Simona Lohan. "A Survey of Spoofer Detection Techniques via Radio Frequency Fingerprinting with Focus on the GNSS Pre-Correlation Sampled Data". Sensors 21, nr 9 (25.04.2021): 3012. http://dx.doi.org/10.3390/s21093012.
Pełny tekst źródłaStreszczenie:
Radio frequency fingerprinting (RFF) methods are becoming more and more popular in the context of identifying genuine transmitters and distinguishing them from malicious or non-authorized transmitters, such as spoofers and jammers. RFF approaches have been studied to a moderate-to-great extent in the context of non-GNSS transmitters, such as WiFi, IoT, or cellular transmitters, but they have not yet been addressed much in the context of GNSS transmitters. In addition, the few RFF-related works in GNSS context are based on post-correlation or navigation data and no author has yet addressed the RFF problem in GNSS with pre-correlation data. Moreover, RFF methods in any of the three domains (pre-correlation, post-correlation, or navigation) are still hard to be found in the context of GNSS. The goal of this paper was two-fold: first, to provide a comprehensive survey of the RFF methods applicable in the GNSS context; and secondly, to propose a novel RFF methodology for spoofing detection, with a focus on GNSS pre-correlation data, but also applicable in a wider context. In order to support our proposed methodology, we qualitatively investigated the capability of different methods to be used in the context of pre-correlation sampled GNSS data, and we present a simulation-based example, under ideal noise conditions, of how the feature down selection can be done. We are also pointing out which of the transmitter features are likely to play the biggest roles in the RFF in GNSS, and which features are likely to fail in helping RFF-based spoofing detection.
16
Nahli, A., E. Simonetto, M. Tatin, S. Durand, L. Morel i V. Lamour. "ON THE COMBINATION OF PSINSAR AND GNSS TECHNIQUES FOR LONG-TERM BRIDGE MONITORING". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B3-2020 (21.08.2020): 325–32. http://dx.doi.org/10.5194/isprs-archives-xliii-b3-2020-325-2020.
Pełny tekst źródłaStreszczenie:
Abstract. Satellite based monitoring techniques are nowadays an emerging tool for structural health monitoring. In this work, we are interested in the study of the deformations of a cable-stayed bridge using both PsInSAR and GNSS techniques. The content of this paper is mainly dedicated to the development and optimization of GNSS and PsInSAR equipments installed on the bridge. We also present the data processing tools with the aim of providing accurate and reliable measurements that will be used to understand the structure behaviour in medium and long terms. We are dealing also with the uncertainty of PsInSAR measurements points localisation to determine accurately where structural motions occur. Results from GNSS show that the bridge undergoes reversible daily and seasonal displacements in the order of few centimetres. PsInSAR results still not completely clear but reveal some limitations related to PS detection on such structures. Future works need to be made on PS detection improvement to exploit GNSS and PsInSAR conjointly for bridge monitoring.
17
Su, Hang, Tao Yang, Kan Wang, Baoqi Sun i Xuhai Yang. "Evaluation of Precipitable Water Vapor Retrieval from Homogeneously Reprocessed Long-Term GNSS Tropospheric Zenith Wet Delay, and Multi-Technique". Remote Sensing 13, nr 21 (8.11.2021): 4490. http://dx.doi.org/10.3390/rs13214490.
Pełny tekst źródłaStreszczenie:
Water vapor is one of the most important greenhouse gases in the world. There are many techniques that can measure water vapor directly or remotely. In this work, we first study the Global Positioning System (GPS)- and the Global Navigation Satellite System (GLONASS)-derived Zenith Wet Delay (ZWD) time series based on 11 years of the second reprocessing campaign of International Global Navigation Satellite Systems (GNSS) Service (IGS) using 320 globally distributed stations. The amount of measurement, the local environment, and the antenna radome are shown to be the main factors that affect the GNSS ZWDs and the corresponding a posteriori formal errors. Furthermore, antenna radome is able to effectively reduce the systematic bias of ZWDs and a posteriori formal errors between the GPS- and GLONASS-based solutions. With the development of the GLONASS, the ZWD differences between the GPS- and the GLONASS-based solutions have gradually decreased to sub-mm-level after GLONASS was fully operated. As the GPS-based Precipitable Water Vapor (PWV) is usually used as the reference to evaluate the other PWV products, the PWV consistency among several common techniques is evaluated, including GNSSs, spaceborne sensors, and numerical products from the European Center for Medium-Range Weather Forecasts (ECMWF). As an example of the results from a detailed comparison analysis, the long-term global analysis shows that the PWV obtained from the GNSS and the ECMWF have great intra-agreements. Based on the global distribution of the magnitude of the PWV and the PWV drift, most of the techniques showed superior agreement and proved their ability to do climate research. With a detailed study performed for the ZWDs and PWV on a long-term global scale, this contribution provides a useful supplement for future research on the GNSS ZWD and PWV.
18
Kweon, Hyeongkeun, Myeongjun Kim, Joon-Woo Lee, Jung Il Seo i Hakjun Rhee. "Comparison of Horizontal Accuracy, Shape Similarity and Cost of Three Different Road Mapping Techniques". Forests 10, nr 5 (24.05.2019): 452. http://dx.doi.org/10.3390/f10050452.
Pełny tekst źródłaStreszczenie:
Accurate spatial information on forest roads is important for forest management and harvest operations. This study evaluated the positional accuracy, shape similarity, and cost of three mapping techniques: GNSS (Global Navigation Satellite System) mapping, CAD file conversion (as-built drawing), and image warping. We chose five road routes within the national forest road system in the Republic of Korea and made digital road maps using each technique. We then compared map accuracy to reference maps made from field surveys. The mapping and field-survey results were compared using point-correspondence, buffering analysis, shape index, and turning function methods. The comparisons indicate that GNSS mapping is the best technique because it generated the highest accuracy (Root Mean Square Error: GNSS mapping 1.28, image warping 7.13, CAD file conversion 13.35), the narrowest buffering width for 95% of the routes overlapped (buffering width: GNSS mapping 1.5 m, image warping 18 m, CAD file conversion 24 m), highest shape similarity (shape index: GNSS mapping 19.6–28.9, image warping 7.2–10.8, CAD file conversion 6.5–7.4), and smallest area size difference in turning function analysis (GNSS mapping 2814–4949, image warping 7972–26,256, CAD file conversion 8661–27,845). However, GNSS requires more time (236 min/km) and costs more ($139.64/km) to produce a digital road map as compared to CAD file conversion (99 min/km and $40.90/km) and image warping (180 min/km and $81.84/km). Managers must decide on the trade-off between accuracy and cost while considering the demand and purpose of maps. GNSS mapping can be used for small-scale mapping or short-haul routes that require a small error range. Image warping was the lowest cost and produced low-accuracy maps, but may be suitable for large-scale mapping at the regional or national level. CAD file conversion was expected to be the most accurate method, because it converted as-built drawings to a map. However, we found that it was the least accurate method, indicating low accuracy of the as-built drawings. Efforts should be made to improve the accuracy of the as-built drawings in Korea.
19
Jin, Chengming, Baigen Cai, Jian Wang i Allison Kealy. "DTM-Aided Adaptive EPF Navigation Application in Railways". Sensors 18, nr 11 (9.11.2018): 3860. http://dx.doi.org/10.3390/s18113860.
Pełny tekst źródłaStreszczenie:
The diverse operating environments change GNSS measurement noise covariance in real time, and different GNSS techniques hold different measurement noise covariance as well. Mismodelling the covariance causes undependable filtering results and even degenerates the GNSS/INS Particle Filter (PF) process, due to the fact that INS error-state noise covariance is much smaller than that of GNSS measurement noise. It also makes the majority of existing methods for adaptively adjusting filter parameters incapable of performing well. In this paper, a feasible Digital Track Map-aided (DTM-aided) adaptive extended Kalman particle filter method is introduced in GNSS/INS integration in order to adjust GNSS measurement noise covariance in real time, and the GNSS down-direction offset is also estimated along with every sampling period through making full use of DTM information. The proposed approach is successfully examined in a railway environment, and the on-site experimental results reveal that the adaptive approach holds better positioning performance in comparison to the methods without adaptive adjustment. Improvements of 62.4% and 14.9% in positioning accuracy are obtained in contrast to Standard Point Positioning (SPP) and Precise Point Positioning (PPP), respectively. The proposed adaptive method takes advantage of DTM information and is able to automatically adapt to complex railway environments and different GNSS techniques.
20
Kowalczyk, Kamil, Katarzyna Pajak, Beata Wieczorek i Bartosz Naumowicz. "An Analysis of Vertical Crustal Movements along the European Coast from Satellite Altimetry, Tide Gauge, GNSS and Radar Interferometry". Remote Sensing 13, nr 11 (2.06.2021): 2173. http://dx.doi.org/10.3390/rs13112173.
Pełny tekst źródłaStreszczenie:
The main aim of the article was to analyse the actual accuracy of determining the vertical movements of the Earth’s crust (VMEC) based on time series made of four measurement techniques: satellite altimetry (SA), tide gauges (TG), fixed GNSS stations and radar interferometry. A relatively new issue is the use of the persistent scatterer InSAR (PSInSAR) time series to determine VMEC. To compare the PSInSAR results with GNSS, an innovative procedure was developed: the workflow of determining the value of VMEC velocities in GNSS stations based on InSAR data. In our article, we have compiled 110 interferograms for ascending satellites and 111 interferograms for descending satellites along the European coast for each of the selected 27 GNSS stations, which is over 5000 interferograms. This allowed us to create time series of unprecedented time, very similar to the time resolution of time series from GNSS stations. As a result, we found that the obtained accuracies of the VMEC determined from the PSInSAR are similar to those obtained from the GNSS time series. We have shown that the VMEC around GNSS stations determined by other techniques are not the same.
21
Gyagenda, Nasser, Jasper V. Hatilima, Hubert Roth i Vadim Zhmud. "A review of GNSS-independent UAV navigation techniques". Robotics and Autonomous Systems 152 (czerwiec 2022): 104069. http://dx.doi.org/10.1016/j.robot.2022.104069.
Pełny tekst źródła
22
Juang, Jyh-Ching, Sheng-Hsiung Ma i Chen-Tsung Lin. "Study of GNSS-R Techniques for FORMOSAT Mission". IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 9, nr 10 (październik 2016): 4582–92. http://dx.doi.org/10.1109/jstars.2016.2575069.
Pełny tekst źródła
23
Lohan, Elena Simona, Diego Alonso de Diego, Jose A. Lopez-Salcedo, Gonzalo Seco-Granados, Pedro Boto i Pedro Fernandes. "Unambiguous Techniques Modernized GNSS Signals: Surveying the solutions". IEEE Signal Processing Magazine 34, nr 5 (wrzesień 2017): 38–52. http://dx.doi.org/10.1109/msp.2017.2711778.
Pełny tekst źródła
24
Park, Je-hong. "GNSS Techniques for Enhancing Flight Safety of UAS". Journal of Advanced Navigation Technology 21, nr 1 (28.02.2017): 58–65. http://dx.doi.org/10.12673/jant.2017.21.1.58.
Pełny tekst źródła
25
Boutiouta, S., i A. Lahcene. "Preliminary study of GNSS meteorology techniques in Algeria". International Journal of Remote Sensing 34, nr 14 (14.04.2013): 5105–18. http://dx.doi.org/10.1080/01431161.2013.786850.
Pełny tekst źródła
26
Huang, Panpan, Chris Rizos i Craig Roberts. "Airborne Pseudolite Distributed Positioning based on Real-time GNSS PPP". Journal of Navigation 72, nr 5 (22.04.2019): 1159–78. http://dx.doi.org/10.1017/s0373463319000213.
Pełny tekst źródłaStreszczenie:
Airborne-Pseudolite (A-PL) systems have been proposed to augment Global Navigation Satellite Systems (GNSSs) in difficult areas where GNSS-only navigation cannot be guaranteed due to signal blockages, signal jamming, etc. One of the challenges in realising such a system is to determine the coordinates of the A-PLs to a high accuracy. The GNSS Precise Point Positioning (PPP) technique is a possible alternative to differential GNSS techniques such as those that generate Real-Time Kinematic (RTK) solutions. To enhance the A-PL positioning performance in GNSS challenged areas, it is assumed that inter-PL range measurements are also used in addition to GNSS measurements. When processing these new measurements, cross-correlations among A-PL estimated states introduced during measurement updates need to be accounted for so as to obtain consistent estimated states. In this paper, a distributed algorithm based on a Split Covariance Intersection Filter (SCIF) is proposed. Three commonly used means of implementing the SCIF algorithm are analysed. Another challenge is that real-time GNSS PPP relies on the use of precise satellite orbit and clock information. One problem is that these real-time orbit and satellite clock error corrections may not be always available, especially for moving A-PLs in challenging environments when signal outages occur. To maintain A-PL positioning accuracy using GNSS PPP, it is necessary to predict these error corrections during outages. Different prediction models for orbit and clock error corrections are discussed. A test was conducted to evaluate the A-PL positioning based on GNSS PPP and inter-PL ranges, as well as the performance of error prediction modelling. It was found that GNSS PPP combined with inter-PL ranges could achieve better converged positioning accuracy and a reduction in convergence time of GNSS PPP. However, the performance of GNSS PPP with inter-PL ranges was degraded by observing A-PLs with limited positioning accuracy. Although the performance improvement achieved by the SCIF-based distributed algorithms was smaller than that by the centralised algorithm, greater robustness in dealing with deteriorated observed A-PLs' trajectory data was demonstrated by the distributed algorithms. In addition, short-term prediction models were analysed, and their performance was shown to reduce the effect of error correction outages on A-PL positioning accuracy.
27
Gao, Yangjun, i Guangyun Li. "A Slowly Varying Spoofing Algorithm on Loosely Coupled GNSS/IMU Avoiding Multiple Anti-Spoofing Techniques". Sensors 22, nr 12 (14.06.2022): 4503. http://dx.doi.org/10.3390/s22124503.
Pełny tekst źródłaStreszczenie:
When satellite navigation terminal sensors encounter malicious signal spoofing or interference, if attention is not paid to improving their anti-spoofing ability, the performance of the sensors will be seriously affected. The global navigation satellite system (GNSS) spoofing has gradually become a research hotspot of the jammer because of its great harm and high concealment. In the face of more and more sensors coupling GNSS and inertial measurement unit (IMU) to varying degrees and configuring a variety of anti-spoofing techniques to effectively detect spoofing, even if the spoofer intends to gradually pull the positioning results, if the spoofing strategy is unreasonable, the parameters of the coupled filter output and spoofing observation measurement will lose their rationality, which will lead to the spoofing being detected. To solve the above problems, in order to effectively counter the non-cooperative target sensors of assembling loosely coupled GNSS/IMU using GNSS spoofing, based on the analysis of the influence mechanism of spoofing on the positioning of loosely coupled GNSS/IMU, a slowly varying spoofing algorithm to avoid loosely coupled GNSS/IMU with multiple anti-spoofing techniques is proposed in this paper, and a measurement deviation determination method to avoid multiple anti-spoofing techniques is proposed, which can gradually pull the positioning results of the coupled system and successfully avoid the detection of anti-spoofing techniques of innovation sequence monitoring and a rationality check on parameters. Simulation experimental results show that the proposed algorithm gradually changes the positioning of loosely coupled GNSS/IMU, the north and east displacements achieve the purpose of spoofing, and error with expected offset is −0.2 m and 2.3 m, respectively. Down displacement also basically achieves the purpose of spoofing, and error with the expected offset is 13.2 m. At the same time, the spoofer avoids the detection of multiple anti-spoofing techniques, does not trigger the system alarm, and realizes the purpose of spoofing; thus, the effectiveness and high concealment of the spoofing algorithm are verified.
28
Kačmařík, Michal, Jan Douša, Galina Dick, Florian Zus, Hugues Brenot, Gregor Möller, Eric Pottiaux i in. "Inter-technique validation of tropospheric slant total delays". Atmospheric Measurement Techniques 10, nr 6 (12.06.2017): 2183–208. http://dx.doi.org/10.5194/amt-10-2183-2017.
Pełny tekst źródłaStreszczenie:
Abstract. An extensive validation of line-of-sight tropospheric slant total delays (STD) from Global Navigation Satellite Systems (GNSS), ray tracing in numerical weather prediction model (NWM) fields and microwave water vapour radiometer (WVR) is presented. Ten GNSS reference stations, including collocated sites, and almost 2 months of data from 2013, including severe weather events were used for comparison. Seven institutions delivered their STDs based on GNSS observations processed using 5 software programs and 11 strategies enabling to compare rather different solutions and to assess the impact of several aspects of the processing strategy. STDs from NWM ray tracing came from three institutions using three different NWMs and ray-tracing software. Inter-techniques evaluations demonstrated a good mutual agreement of various GNSS STD solutions compared to NWM and WVR STDs. The mean bias among GNSS solutions not considering post-fit residuals in STDs was −0.6 mm for STDs scaled in the zenith direction and the mean standard deviation was 3.7 mm. Standard deviations of comparisons between GNSS and NWM ray-tracing solutions were typically 10 mm ± 2 mm (scaled in the zenith direction), depending on the NWM model and the GNSS station. Comparing GNSS versus WVR STDs reached standard deviations of 12 mm ± 2 mm also scaled in the zenith direction. Impacts of raw GNSS post-fit residuals and cleaned residuals on optimal reconstructing of GNSS STDs were evaluated at inter-technique comparison and for GNSS at collocated sites. The use of raw post-fit residuals is not generally recommended as they might contain strong systematic effects, as demonstrated in the case of station LDB0. Simplified STDs reconstructed only from estimated GNSS tropospheric parameters, i.e. without applying post-fit residuals, performed the best in all the comparisons; however, it obviously missed part of tropospheric signals due to non-linear temporal and spatial variations in the troposphere. Although the post-fit residuals cleaned of visible systematic errors generally showed a slightly worse performance, they contained significant tropospheric signal on top of the simplified model. They are thus recommended for the reconstruction of STDs, particularly during high variability in the troposphere. Cleaned residuals also showed a stable performance during ordinary days while containing promising information about the troposphere at low-elevation angles.
29
Lindskog, Magnus, Martin Ridal, Sigurdur Thorsteinsson i Tong Ning. "Data assimilation of GNSS zenith total delays from a Nordic processing centre". Atmospheric Chemistry and Physics 17, nr 22 (24.11.2017): 13983–98. http://dx.doi.org/10.5194/acp-17-13983-2017.
Pełny tekst źródłaStreszczenie:
Abstract. Atmospheric moisture-related information estimated from Global Navigation Satellite System (GNSS) ground-based receiver stations by the Nordic GNSS Analysis Centre (NGAA) have been used within a state-of-the-art kilometre-scale numerical weather prediction system. Different processing techniques have been implemented to derive the moisture-related GNSS information in the form of zenith total delays (ZTDs) and these are described and compared. In addition full-scale data assimilation and modelling experiments have been carried out to investigate the impact of utilizing moisture-related GNSS data from the NGAA processing centre on a numerical weather prediction (NWP) model initial state and on the ensuing forecast quality. The sensitivity of results to aspects of the data processing, station density, bias-correction and data assimilation have been investigated. Results show benefits to forecast quality when using GNSS ZTD as an additional observation type. The results also show a sensitivity to thinning distance applied for GNSS ZTD observations but not to modifications to the number of predictors used in the variational bias correction applied. In addition, it is demonstrated that the assimilation of GNSS ZTD can benefit from more general data assimilation enhancements and that there is an interaction of GNSS ZTD with other types of observations used in the data assimilation. Future plans include further investigation of optimal thinning distances and application of more advanced data assimilation techniques.
30
Groves, Paul D., i Christopher J. Mather. "Receiver Interface Requirements for Deep INS/GNSS Integration and Vector Tracking". Journal of Navigation 63, nr 3 (28.05.2010): 471–89. http://dx.doi.org/10.1017/s0373463310000093.
Pełny tekst źródłaStreszczenie:
Vector tracking of global navigation satellite systems (GNSS) signals and deeply integrating GNSS with an inertial navigation system (INS) improve robustness and accuracy in poor GNSS signal-to-noise environments. Both require a dedicated interface between the GNSS receiver and the navigation processor to enable the GNSS receiver to output the correlator measurements and input numerically-controlled oscillator (NCO) commands. This paper investigates the requirements for such an interface. Data latency is analysed for a range of different stand-alone GNSS vector tracking and deep INS/GNSS integration architectures. Suitable latency compensation techniques are identified. It is shown that, for the majority of applications, an NCO command update rate of 50 Hz with latency compensation and 100 Hz without is sufficient. An approach to interface standardisation which can handle a wide range of different GNSS signals and receiver designs is proposed.
31
Dobelis, Didzis, i Jānis Zvirgzds. "NETWORK RTK PERFORMANCE ANALYSIS: A CASE STUDY IN LATVIA". Geodesy and cartography 42, nr 3 (22.09.2016): 69–74. http://dx.doi.org/10.3846/20296991.2016.1226383.
Pełny tekst źródłaStreszczenie:
Nowadays the RTK (Real Time Kinematic) method for positioning is used in daily life by different consumers for many purposes. Several different RTK correction techniques are used, starting from single site to network approaches. The GNSS market is filled with receivers from different manufacturers and different capabilities. In this paper we assess the stability of the reference station network transmitted RTK correction. Two different surveying class GNSS receivers in combination with four varied RTK correction techniques under diverse observation conditions are analyzed. This study has been conducted in Latvia, where state wide permanent GNSS reference station network has been maintained since year 2005.
32
Fellner, Andrzej, i Henryk Jafernik. "Implementation of Satellite Techniques in the Air Transport". Reports on Geodesy and Geoinformatics 100, nr 1 (1.06.2016): 39–53. http://dx.doi.org/10.1515/rgg-2016-0005.
Pełny tekst źródłaStreszczenie:
Abstract The article shows process of the implementation satellite systems in Polish aviation which contributed to accomplishment Performance-Based Navigation (PBN) concept. Since 1991 authors have introduced Satellite Navigation Equipment in Polish Air Forces. The studies and researches provide to the Polish Air Force alternative approaches, modernize their navigation and landing systems and achieve compatibility with systems of the North Atlantic Treaty Organization (NATO) and International Civil Aviation Organization (ICAO). Acquired experience, conducted military tests and obtained results enabled to take up work scientifically - research in the environment of the civil aviation. Therefore in 2008 there has been launched cooperation with Polish Air Navigation Services Agency (PANSA). Thanks to cooperation, there have been compiled and fulfilled three fundamental international projects: EGNOS APV MIELEC (EGNOS Introduction in European Eastern Region - APV Mielec), HEDGE (Helicopters Deploy GNSS in Europe), SHERPA (Support ad-Hoc to Eastern Region Pre-operational in GNSS). The successful completion of these projects enabled implementation 21 procedures of the RNAV GNSS final approach at Polish airports, contributing to the implementation of PBN in Poland as well as ICAO resolution A37-11. Results of conducted research which served for the implementation of satellite techniques in the air transport constitute the meaning of this material.
33
Erenoglu, R. Cuneyt, Mehmet Ali Yucel, Atinc Pirti i D. Ugur Sanli. "On the performance of GNSS levelling over steep slopes". Boletim de Ciências Geodésicas 18, nr 4 (grudzień 2012): 645–60. http://dx.doi.org/10.1590/s1982-21702012000400008.
Pełny tekst źródłaStreszczenie:
In geodetic applications variety, one of the main current focuses is recently to determine the heights of ground stations with high accuracy. Specially the possibility of acquiring 3D information of the point positioning with high accuracy is opening up new strategies of investigating the heighting. Global Navigation Satellite System (GNSS) for 3D positioning is undergoing rapid developments and GNSS heighting can be an alternative to terrestrial techniques of height measurements. This paper presents a research study on the use of GNSS heighting in the case of steep slopes and multipath issue. Short baseline solution strategies were performed by using Bernese Software v. 5.0. The analysis results are also compared to the results of techniques of the terrestrial levelling. The results show that GNSS can be used as an practical surveying method to the terrestrial levelling with comparable accuracies. Furthermore, one can save up to 1 hour using GNSS instead of geometric levelling over a steep slope of a 100 m. On the other hand, as usual multipath is the primary error source decreasing the efficiency of GNSS, and it has been studied experimentally in this paper.
34
BİLGEN, Burhaneddin, i Cevat İNAL. "Investigation of Vertical Deformations with GNSS Technique". Afyon Kocatepe University Journal of Sciences and Engineering 22, nr 3 (30.06.2022): 615–25. http://dx.doi.org/10.35414/akufemubid.1066483.
Pełny tekst źródłaStreszczenie:
Monitoring and analysis of deformations in the earth's crust and engineering structures are among the important issues of geodesy. In order to monitor the deformations, a geodetic network consisting of reference and object points is created in general. Deformation research is carried out by analyzing the movements at the network points. Measurements for the determination of these movements can be made with classical techniques as well as with GNSS techniques. The static relative positioning is a widely used method in such precise geodetic applications. In this study; the capacity of the GNSS technique to detect vertical deformations was investigated. For this purpose, a micro geodetic network was designed in the Selcuk University Campus area. A mechanism to create virtual deformations was placed on the object point in the designed network and periodic measurements were carried out by creating virtual deformations in the vertical direction. Measurements were processed with the Bernese v5.2 scientific GNSS software, analyzed by Iterative Weighted Similarity Transformation Method using the software developed to perform deformation analysis in GNSS networks, and the determined deformations were compared with the real deformation value, considering the ionospheric activities on the measurement days. As a result of the analyses, vectorial deformation amounts compatible with the real deformation value were obtained and it was seen that the motion amounts in the direction of the coordinate components were also compatible with the virtual deformation amount given on the mechanism.
35
Dieng, Mbaye, Siva Sankar, Pingping Ni, Ileana Florea, Pedro Alpuim, Andrea Capasso, Abderrahim Yassar i Fatima Zahra Bouanis. "Solution-Processed Functionalized Graphene Film Prepared by Vacuum Filtration for Flexible NO2 Sensors". Sensors 23, nr 4 (7.02.2023): 1831. http://dx.doi.org/10.3390/s23041831.
Pełny tekst źródłaStreszczenie:
Large-scale production of graphene nanosheets (GNSs) has led to the availability of solution-processable GNSs on the commercial scale. The controlled vacuum filtration method is a scalable process for the preparation of wafer-scale films of GNSs, which can be used for gas sensing applications. Here, we demonstrate the use of this deposition method to produce functional gas sensors, using a chemiresistor structure from GNS solution-based techniques. The GNS suspension was prepared by liquid-phase exfoliation (LPE) and transferred to a polyvinylidene fluoride (PVDF) membrane. The effect of non-covalent functionalization with Co-porphyrin and Fe-phthalocyanines on the sensor properties was studied. The pristine and functionalized GNS films were characterized using different techniques such as Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and electrical characterizations. The morphological and spectroscopic analyses both confirm that the molecules (Co-porphyrin and Fe-phthalocyanine) were successfully adsorbed onto the GNSs surface through π-π interactions. The chemiresistive sensor response of functionalized GNSs toward the low concentrations of nitrogen dioxide (NO2) (0.5–2 ppm) was studied and compared with those of the film of pristine GNSs. The tests on the sensing performance clearly showed sensitivity to a low concentration of NO2 (5 ppm). Furthermore, the chemical modification of GNSs significantly improves NO2 sensing performance compared to the pristine GNSs. The sensor response can be modulated by the type of adsorbed molecules. Indeed, Co-Por exhibited negative responsiveness (the response of Co-Por-GNS sensors and pristine GNS devices was 13.1% and 15.6%, respectively, after exposure to 0.5 ppm of NO2). Meanwhile, Fe-Phc-GNSs induced the opposite behavior resulting in an increase in the sensor response (the sensitivity was 8.3% and 7.8% of Fe-Phc-GNSs and pristine GNSs, respectively, at 0.5 ppm NO2 gas).
36
Yu, Kegen, Shuai Han, Jinwei Bu, Yuhang An, Zhewen Zhou, Changyang Wang, Sajad Tabibi i Joon Wayn Cheong. "Spaceborne GNSS Reflectometry". Remote Sensing 14, nr 7 (27.03.2022): 1605. http://dx.doi.org/10.3390/rs14071605.
Pełny tekst źródłaStreszczenie:
This article presents a review on spaceborne Global Navigation Satellite System Reflectometry (GNSS-R), which is an important part of GNSS-R technology and has attracted great attention from academia, industry and government agencies in recent years. Compared with ground-based and airborne GNSS-R approaches, spaceborne GNSS-R has a number of advantages, including wide coverage and the ability to sense medium- and large-scale phenomena such as ocean eddies, hurricanes and tsunamis. Since 2014, about seven satellite missions have been successfully conducted and a large number of spaceborne data were recorded. Accordingly, the data have been widely used to carry out a variety of studies for a range of useful applications, and significant research outcomes have been generated. This article provides an overview of these studies with a focus on the basic methods and techniques in the retrieval of a number of geophysical parameters and the detection of several objects. The challenges and future prospects of spaceborne GNSS-R are also addressed.
37
Ayfantopoulou, Georgia, Marios Nikolaos Militsis, Josep Maria Salanova Grau i Socrates Basbas. "Improving Map Matching of Floating Car Data with Artificial Intelligence Techniques". Information 13, nr 11 (24.10.2022): 508. http://dx.doi.org/10.3390/info13110508.
Pełny tekst źródłaStreszczenie:
Map matching is a crucial data processing task for transferring measurements from the dynamic sensor location to the relevant road segment. It is especially important when estimating road network speed by using probe vehicles (floating car data) as speed measurement sensors. Most common approaches rely on finding the closet road segment, but road network geometry (e.g., dense areas, two-way streets, and superposition of road segments due to different heights) and inaccuracy in the GNSS location (up to decades of meters in urban areas) can wrongly allocate up to 30% of the measurements. More advanced methods rely on taking the topology of the network into account, significantly improving the accuracy at a higher computational cost, especially when the accuracy of the GNSS location is low. In order to both improve the accuracy of the “closet road segment” methods and reduce the processing time of the topology-based methods, the data can be pre-processed using AI techniques to reduce noise created by the inaccuracy of the GNSS location and improve the overall accuracy of the map-matching task. This paper applies AI to correct GNSS locations and improve the map-matching results, achieving a matching accuracy of 76%. The proposed methodology is demonstrated to the floating car data generated by a fleet of 1200 taxi vehicles in Thessaloniki used to estimate road network speed in real time for information services and for supporting traffic management in the city.
38
Zárate, Belizario A., Rachid El Hamdouni i Tomás Fernández. "GNSS and RPAS Integration Techniques for Studying Landslide Dynamics: Application to the Areas of Victoria and Colinas Lojanas, (Loja, Ecuador)". Remote Sensing 13, nr 17 (3.09.2021): 3496. http://dx.doi.org/10.3390/rs13173496.
Pełny tekst źródłaStreszczenie:
This research tests the application of GNSS and RPAS techniques to the spatiotemporal analysis of landslide dynamics. Our method began by establishing non-permanent GNSS networks on the slope surfaces to perform periodic measurements by differential GNSS. Similarly, RPAS flights were made to acquire high-resolution images, which were oriented and georeferenced using ground control points and structure-from-motion algorithms to ultimately obtain digital surface models and orthophotos. Based on GNSS measurements, the direction and velocity of displacements were accurately calculated, and orthophotos and DSMs were used to calculate horizontal and vertical displacements in a set of significant points throughout the study area, reaching accuracies higher than 0.035 m in the GNSS data and 0.10 m in the RPAS data. These values were within the accuracy required for such studies. Based on the field observations and the results from the photogrammetric studies, the two studied landslides were classified as very slow flows. These techniques are the basis for establishing early warning systems in areas of natural hazards based on the calculation of displacement speeds of the surface of slopes.
39
Marcinek, Krzysztof, i Witold A. Pleskacz. "GNSS-ISE: Instruction Set Extension for GNSS Baseband Processing". Sensors 20, nr 2 (14.01.2020): 465. http://dx.doi.org/10.3390/s20020465.
Pełny tekst źródłaStreszczenie:
This work presents the results of research toward designing an instruction set extension dedicated to Global Navigation Satellite System (GNSS) baseband processing. The paper describes the state-of-the-art techniques of GNSS receiver implementation. Their advantages and disadvantages are discussed. Against this background, a new versatile instruction set extension for GNSS baseband processing is presented. The authors introduce improved mechanisms for instruction set generation focused on multi-channel processing. The analytical approach used by the authors leads to the introduction of a GNSS-instruction set extension (ISE) for GNSS baseband processing. The developed GNSS-ISE is simulated extensively using PC software and field-programmable gate array (FPGA) emulation. Finally, the developed GNSS-ISE is incorporated into the first-in-the-world, according to the authors’ best knowledge, integrated, multi-frequency, and multi-constellation microcontroller with embedded flash memory. Additionally, this microcontroller may serve as an application processor, which is a unique feature. The presented results show the feasibility of implementing the GNSS-ISE into an embedded microprocessor system and its capability of performing baseband processing. The developed GNSS-ISE can be implemented in a wide range of applications including smart IoT (internet of things) devices or remote sensors, fostering the adaptation of multi-frequency and multi-constellation GNSS receivers to the low-cost consumer mass-market.
40
Ribó, Serni, Weiqiang Li, Estel Cardellach, Fran Fabra, Ramon Padullés, Antonio Rius i Manuel Martín-Neira. "Experimental Validation of GNSS Interferometric Radio Occultation". Remote Sensing 11, nr 23 (23.11.2019): 2758. http://dx.doi.org/10.3390/rs11232758.
Pełny tekst źródłaStreszczenie:
In this work, we present experimental results on the interferometric radio occultation (iRO) signal processing techniques, and compare the performance to the closed-loop and open-loop processing used in conventional radio occultation measurements. We also discuss the effects of antenna beam width to mitigate inter-satellite interferences, as well as how the local oscillator stability affects the obtained Doppler estimates. The required signal processing resources are less stringent for the iRO than for conventional RO techniques. In addition, the zenith iRO has a comparable performance to the well-established RO techniques.
41
Jiang, Wei, Yong Li, Chris Rizos, Baigen Cai i Wei Shangguan. "Seamless Indoor-Outdoor Navigation based on GNSS, INS and Terrestrial Ranging Techniques". Journal of Navigation 70, nr 6 (11.07.2017): 1183–204. http://dx.doi.org/10.1017/s037346331700042x.
Pełny tekst źródłaStreszczenie:
We describe an integrated navigation system based on Global Navigation Satellite Systems (GNSS), an Inertial Navigation System (INS) and terrestrial ranging technologies that can support accurate and seamless indoor-outdoor positioning. To overcome severe multipath disturbance in indoor environments, Locata technology is used in this navigation system. Such a “Locata-augmented” navigation system can operate in different positioning modes in both indoor and outdoor environments. In environments where GNSS is unavailable, e.g. indoors, the proposed system is designed to operate in the Locata/INS “loosely-integrated” mode. On the other hand, in outdoor environments, all GNSS, Locata and INS measurements are available, and all useful information can be fused via a decentralised Federated Kalman filter. To evaluate the proposed system for seamless indoor-outdoor positioning, an indoor-outdoor test was conducted at a metal-clad warehouse. The test results confirmed that the proposed navigation system can provide continuous and reliable position and attitude solutions, with the positioning accuracy being better than five centimetres.
42
Abukari, Osman Mohammed, Akwasi Afrifa Acheampong, Isaac Dadzie i Samuel Osah. "Congruence through repeatability of position solutions by different GNSS survey techniques". South African Journal of Geomatics 11, nr 2 (1.09.2022): 274–89. http://dx.doi.org/10.4314/sajg.v11i2.8.
Pełny tekst źródłaStreszczenie:
In this study, we determined three-dimensional (3D) position coordinates for eight new Continuous Operating Reference Stations (CORS) in Ghana through three different GNSS positioning techniques. The three GNSS positioning techniques whereby the network of CORS was tied to ITRF14 and War Office 1926 datums included:1) Precise Point Positioning (PPP); 2) Precise Differential GNSS (PDGNSS), using reference stations based on ITRF14; and 3) PDGNSS, using reference stations based on War Office. The PPP solutions were computed using the Canadian Spatial Reference System Precise Point Positioning software (CSRS-PPP), available online and as an open source GNSS laboratory tool software (gLAB). The PDGNSS solutions were obtained from OPUS and AUSPOS online services, as well as from self-post-processing using Topcon Tools software v8.2.3. All solutions were computed using 24-hour data for twelve consecutive days in the month of October 2018 (GPS DoY 284 to GPS DoY 295). The quality, reliability, and acceptability of position solutions were measured by computing the average positioning error, the rate of ambiguity resolution and the repeatability ratios of the solutions. The variability of coordinate differences for each pair of different positioning techniques was computed to determine their solution congruences. Ultimately, , the average positioning errors in northing, easting, and height were 0.003m, 0.005m and 0.009m, respectively. The rate of ambiguity resolution was between 75.3% and 90.3%. Repeatability ratios ranged between 1: 68,500,000 and 1: 411,100,000. Finally, the minimum and maximum range of variability in coordinate differences for each pair of positioning techniques was 1mm to 16mm for horizontal positions and 2mm to 137mm for vertical positions.
43
SHEN, Nan, Liang CHEN, Jingbin LIU, Lei WANG, Tingye TAO, Dewen WU i Ruizhi CHEN. "A Review of Global Navigation Satellite System (GNSS)-based Dynamic Monitoring Technologies for Structural Health Monitoring". Remote Sensing 11, nr 9 (26.04.2019): 1001. http://dx.doi.org/10.3390/rs11091001.
Pełny tekst źródłaStreszczenie:
In the past few decades, global navigation satellite system (GNSS) technology has been widely used in structural health monitoring (SHM), and the monitoring mode has evolved from long-term deformation monitoring to dynamic monitoring. This paper gives an overview of GNSS-based dynamic monitoring technologies for SHM. The review is classified into three parts, which include GNSS-based dynamic monitoring technologies for SHM, the improvement of GNSS-based dynamic monitoring technologies for SHM, as well as denoising and detrending algorithms. The significance and progress of Real-Time Kinematic (RTK), Precise Point Position (PPP), and direct displacement measurement techniques, as well as single-frequency technology for dynamic monitoring, are summarized, and the comparison of these technologies is given. The improvement of GNSS-based dynamic monitoring technologies for SHM is given from the perspective of multi-GNSS, a high-rate GNSS receiver, and the integration between the GNSS and accelerometer. In addition, the denoising and detrending algorithms for GNSS-based observations for SHM and corresponding applications are summarized. Challenges of low-cost and widely covered GNSS-based technologies for SHM are discussed, and problems are posed for future research.
44
Yuwono, B. D., S. Subiyanto, A. S. Pratomo i Najib. "Time Series of Land subsidence rate on Coastal Demak Using GNSS CORS UDIP and DINSAR". E3S Web of Conferences 94 (2019): 04004. http://dx.doi.org/10.1051/e3sconf/20199404004.
Pełny tekst źródłaStreszczenie:
Most of the studies land subsidence and impact have been done on the north coastal area of Java, especially Semarang and Demak. This landsubsidence has a very serious impact both in the infra structure, the economy and the environment. Techniques of observing landsubsidence using geodetic methods have been widely practiced. Geodetic technology is undergoing rapid development, especially in GNSS navigation satellite technology as well as satellite radar interferometry. Both have advantages and disadvantages of each. In this study will examine the application of DinSAR interferometric techniques and GNSS technology to predict the rate of land subsidence coastal of Demak regency. This paper also emphasize the role of GNSS and DinSAR application in deformation especially for landsubsidence monitoring.
45
Vu, Ngoc Quang, Viet Ha Nguyen, Le Binh Ta i Hung Tien Van. "A Comparative Study of UAV Lidar, UAV, and GNSS RTK on Infrastructure Survey". IOP Conference Series: Materials Science and Engineering 1289, nr 1 (1.08.2023): 012098. http://dx.doi.org/10.1088/1757-899x/1289/1/012098.
Pełny tekst źródłaStreszczenie:
Abstract The advancement of the latest techniques allows surveyors to have various approaches to solving survey tasks. The paper is an experimental study on collecting terrain data using different techniques including Lidar on a UAV, normal UAV, and GNSS-RTK. The study uses the point clouds extracted from Agisoft for data from Phantom 4 RTK, and Copre for data from Lidar. The lidar method uses AA450, the first lidar product line of the CHC brand in Vietnam with a Livox Avia scanner. UAV phantom4 RTK uses a 1” CMOS camera, with 20M effective pixels. Both Lidar and UAV methods use the PPK processing technique, and flight altitude is 80m and 100m respectively while GNSS-RTK uses the single-base method at around 7km distance between base and rover. The study results show the deviations in coordinates are very small, and the differences in elevation of Lidar and Phantom4 RTK compare to GNSS-RTK range from 3-5cm at open positions. The differences in elevation between Lidar - GNSS-RTK and Phantom 4RTK-GNSS RTK are 5-8cm and 10-15 cm respectively at the low vegetation and sparse density positions. The differences in elevation between Lidar and GNSS-RTK method range from 8-15cm while Phantom 4RTK cannot reach the ground point at the high and dense vegetation. However, the deviations in elevation between Lidar and GNSS-RTK are 15-25cm at the low, dense positions.
46
Tamimi, R., i C. Toth. "ASSESSING THE VIABILITY OF PPK TECHNIQUES FOR ACCURATE MAPPING WITH UAS". International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVIII-1/W1-2023 (25.05.2023): 479–88. http://dx.doi.org/10.5194/isprs-archives-xlviii-1-w1-2023-479-2023.
Pełny tekst źródłaStreszczenie:
Abstract. Utilizing ground control points (GCPs) to georeference photogrammetry-based point cloud data is a common practice in unmanned aerial system (UAS) mapping. Direct georeferencing or integrated sensor orientation (ISO) can be used to obtain georeferenced point clouds from UAS without relying heavily on GCPs. However, the accuracy of the point cloud may be impacted by the accuracy of the trajectory solution obtained by GNSS. To improve point cloud accuracy, post-processing kinematic (PPK) solutions can be applied to the UAS trajectory, which may provide higher accuracy than low-accuracy trajectory solutions and minimize the reliance on GCPs. This study compares the accuracy and precision of two different point clouds generated using different methods. One point cloud was generated using traditional photogrammetric methods with low accuracy Global Navigation Satellite System (GNSS) observations from the UAS and GCPs that have an average accuracy of one to two centimeters, while the other was generated using PPK trajectory solution for the UAS’s trajectory with two software: open-source Emlid Studio and the widely used Inertial Explorer. The use of PPK techniques in UAS mapping may have several potential benefits over traditional methods. By correcting the errors in the UAS's trajectory, a user may only need to depend on fewer ground control points, which can reduce the time and cost associated with fieldwork. This is particularly useful in areas that are difficult to access or have limited ground control point options, such as in urban or forested areas. To evaluate performance, a GNSS receiver is used to obtain measurements on checkpoints, which are used to assess the accuracies of the point clouds. In our experiments, the accuracy of the point clouds generated using PPK trajectory solution with high accuracy GCPs was found to be higher than those generated with low accuracy GNSS observations while aided with high accuracy ground control points. While the use of PPK with GCPs is generally expected to provide more accurate and reliable data than low-accuracy GNSS observations even after adjusting with GCPs, the number and distribution of GCPs can still significantly impact overall accuracy. Therefore, careful consideration of the number of GCPs and their placement is essential to achieve the desired level of efficiency and effectiveness in UAS mapping.
47
Qu, Xuanyu, Bao Shu, Xiaoli Ding, Yangwei Lu, Guopeng Li i Li Wang. "Experimental Study of Accuracy of High-Rate GNSS in Context of Structural Health Monitoring". Remote Sensing 14, nr 19 (7.10.2022): 4989. http://dx.doi.org/10.3390/rs14194989.
Pełny tekst źródłaStreszczenie:
Global Navigation Satellite Systems (GNSS)-based technologies have become an indispensable part of current structural health monitoring (SHM) systems because of the unique capability of the GNSS technologies to provide accurate real-time displacement information. GNSS equipment with a data sampling rate of up to about 20 Hz has been widely used for this purpose. High-rate GNSS systems (typically up to about 100 Hz) offer additional advantages in structural health monitoring as some highly dynamic civil structures, such as some bridges, require high-rate monitoring data to capture the dynamic behaviors. However, the performance of high-rate GNSS positioning in the context of structural health monitoring is not entirely known, as studies on structural monitoring with high-rate GNSS positioning are very limited, especially considering that some of the satellite systems just reached their full constellations very recently. We carried out a series of experiments with the help of a shaking table to assess the SHM performance of a set of 100 Hz GNSS equipment and three commonly used GNSS positioning techniques, PPP (precise point positioning), PPP-AR (precise point positioning with ambiguity resolution), and RTK (real-time kinematic). We found that the standard deviations of the 100 Hz GNSS displacement solutions derived from PPP, PPP-AR, and RTK techniques were 5.5 mm, 3.6 mm, and 0.8 mm, respectively, when the antenna was in quasi-static motion, and about 9.2 mm, 6.2 mm, and 3.5 mm, respectively, when the antenna was in vibration (up to about 0.7 Hz), under typical urban observational conditions in Hong Kong. We also found that the higher a sampling rate is, the lower the accuracy of a measured displacement series is. On average, the 10 Hz and 100 Hz results are 5.5% and 10.3%, respectively, noisier than the 1 Hz results.
48
Adeseye, Temitayo A., i Gafar Suara. "3D-Position Determination using GNSS Techniques – A Comparative Analysis". European Journal of Engineering and Technology Research 6, nr 4 (6.05.2021): 1–5. http://dx.doi.org/10.24018/ejers.2021.6.4.2435.
Pełny tekst źródłaStreszczenie:
This study was carried out to determine 3D-position of selected points within Obafemi Awolowo University. The points were located at Africa Regional Institute for Geospatial Information Science and Technology (AFRIGST), Central Technological and Laboratory Workshops (CTLW), main Bus Stop, Religion ground, New Environmental Design and Management (New EDM), and Spider building. China HuaCe Corporation (CHC) GPS and Promark 3 GPS were used to carry out observation on the selected points. The data gotten were post processed using GNSS solution software for Promark3, Compass software for CHC GPS and the result gotten were compared with the known coordinates of those points. The data was analyzed using Statistical Package for Social Sciences (SPSS) to determine the most accurate instrument between the two. The occupation time for the two instruments on each station was 45 minutes. Analysis of Variance (ANOVA) and Chi square Variance analysis were conducted, the result showed that there is no significant difference between the observations of the two instruments in comparison with the adjusted coordinate. It can be concluded that any of the two instruments can be used for 3D point positioning to obtain accurate result.
49
David, Ciprian, Corina Nafornita, Vasile Gui, Andrei Campeanu, Guillaume Carrie i Michel Monnerat. "GNSS Localization in Constraint Environment by Image Fusing Techniques". Remote Sensing 13, nr 10 (20.05.2021): 2021. http://dx.doi.org/10.3390/rs13102021.
Pełny tekst źródłaStreszczenie:
Satellite localization often suffers in terms of accuracy due to various reasons. One possible source of errors is represented by the lack of means to eliminate Non-Line-of-Sight satellite-related data. We propose here a method for fusing existing data with new information, extracted by using roof-mounted cameras and adequate image processing algorithms. The roof-mounted camera is used to robustly segment the sky regions. The localization approach can benefit from this new information as it offers a way of excluding the Non-Line-of-Sight satellites. The output of the camera module is a probability map. One can easily decide which satellites should not be used for localization, by manipulating this probability map. Our approach is validated by extensive tests, which demonstrate the improvement of the localization itself (Horizontal Positioning Error reduction) and a moderate degradation of Horizontal Protection Level due to the Dilution of Precision phenomenon, which appears as a consequence of the reduction of the satellites’ number used for localization.
50
YAMAGUCHI, Daisuke, Nozomi KUDO, Yosuke ICHIYANAGI i Tomonori HASEGAWA. "Accuracy Evaluation Techniques of train position detection using GNSS". Proceedings of the Transportation and Logistics Conference 2021.30 (2021): SS7–2–2. http://dx.doi.org/10.1299/jsmetld.2021.30.ss7-2-2.
Pełny tekst źródła