ASSESSMENT OF VELOCITY ACCURACY OF AIRCRAFT IN THE DYNAMIC TESTS USING GNSS SENSORS

The paper presents a new model for determining the accurate and reliable flight speed of an aircraft based on navigation data from the three independent Global Navigation Satellite System (GNSS) receivers. The GNSS devices were mounted on-board of a Cessna 172 aircraft during a training flight in south-eastern Poland. The speed parameter was determined as the resultant value based on individual components from 3 independent solutions of the motion model. In addition, the standard deviation of the determined flight speed values for the Cessna 172 aircraft was determined in the paper. The resultant on-ground and flight speed of the Cessna 172 aircraft ranged from 0.23 m/s to 74.81 m/s, while the standard deviation of the determined speed values varied from 0.01 m/s to 1.07 m/s. In addition, the accuracy of research method equals to -0.46 m/s to +0.61 m/s, in respect to the RTK-OTF solution. The RMS parameter as an accuracy term amounts to 0.07 m/s for the presented research method.

Download Full-text

Galileo L10 Satellites: Orbit, Clock and Signal-in-Space Performance Analysis

Sensors ◽

10.3390/s21051695 ◽

2021 ◽

Vol 21 (5) ◽

pp. 1695

Author(s):

Constantin-Octavian Andrei ◽

Sonja Lahtinen ◽

Markku Poutanen ◽

Hannu Koivula ◽

Jan Johansson

Keyword(s):

Performance Indicators ◽

Satellite System ◽

Short Term ◽

Orbital Inclination ◽

Navigation Data ◽

Periodic Signals ◽

Global Navigation Satellite ◽

Minor Correction ◽

Very High

The tenth launch (L10) of the European Global Navigation Satellite System Galileo filled in all orbital slots in the constellation. The launch carried four Galileo satellites and took place in July 2018. The satellites were declared operational in February 2019. In this study, we report on the performance of the Galileo L10 satellites in terms of orbital inclination and repeat period parameters, broadcast satellite clocks and signal in space (SiS) performance indicators. We used all available broadcast navigation data from the IGS consolidated navigation files. These satellites have not been reported in the previous studies. First, the orbital inclination (56.7±0.15°) and repeat period (50680.7±0.22 s) for all four satellites are within the nominal values. The data analysis reveals also 13.5-, 27-, 177- and 354-days periodic signals. Second, the broadcast satellite clocks show different correction magnitude due to different trends in the bias component. One clock switch and several other minor correction jumps have occurred since the satellites were declared operational. Short-term discontinuities are within ±1 ps/s, whereas clock accuracy values are constantly below 0.20 m (root-mean-square—rms). Finally, the SiS performance has been very high in terms of availability and accuracy. Monthly SiS availability has been constantly above the target value of 87% and much higher in 2020 as compared to 2019. Monthly SiS accuracy has been below 0.20 m (95th percentile) and below 0.40 m (99th percentile). The performance figures depend on the content and quality of the consolidated navigation files as well as the precise reference products. Nevertheless, these levels of accuracy are well below the 7 m threshold (95th percentile) specified in the Galileo service definition document.

Download Full-text

Monitoring Aircraft Position Using EGNOS Data for the SBAS APV Approach to the Landing Procedure

Sensors ◽

10.3390/s20071945 ◽

2020 ◽

Vol 20 (7) ◽

pp. 1945 ◽

Cited By ~ 3

Author(s):

Kamil Krasuski ◽

Damian Wierzbicki

Keyword(s):

Research Method ◽

Satellite System ◽

Civil Aviation ◽

International Civil Aviation Organization ◽

Positioning Accuracy ◽

Research Findings ◽

Global Navigation Satellite ◽

Service Data ◽

Computational Strategy ◽

Better Than

The aim of this paper is to present the problem of the implementation of the EGNOS (European Geostationary Navigation Overlay Service) data for the processing of aircraft position determination. The main aim of the research is to develop a new computational strategy which might improve the performance of the EGNOS system in aviation, based on navigation solutions of an aircraft position, using several GNSS (Global Navigation Satellite System) onboard receivers. The results of an experimental test conducted by the Cessna 172 at EPDE (European Poland Deblin) (ICAO (International Civil Aviation Organization) code, N51°33.07’/E21°53.52’) aerodrome in Dęblin are presented and discussed in this paper. Two GNSS navigation receivers with the EGNOS positioning function for monitoring changes in the parameters of the aircraft position in real time during the landing phase were installed onboard a Cessna 172. Based on obtained research findings, it was discovered that the positioning accuracy was not higher than 2.1 m, and the integrity of positioning did not exceed 19 m. Moreover, the availability parameter was found to equal 1 (or 100%); also, no intervals in the continuity of the operation of the EGNOS system were recorded. In the paper, the results of the air test from Dęblin were compared with the parameters of positioning quality from the air test conducted in Chełm (ICAO code: EPCD, N51°04’57.8” E23°26’15”). In the air test in Chełm, the obtained parameters of EGNOS quality positioning were: better than 4.9 m for accuracy, less than 35.5 m for integrity, 100% for availability, and no breaks in continuity. Based on the results of the air tests in Dęblin and Chełm, it was concluded that the parameters of the EGNOS positioning quality in aviation for the SBAS (Satellite Based Augmentation System) APV (Approach to Vertical guidance) procedure were satisfied in accordance with the ICAO (International Civil Aviation Organization) requirements. The presented research method can be utilized in the SBAS APV landing procedure in Polish aviation. In this paper, the results of PDOP (Position Dilution of Precision) are presented and compared to the two air tests in Dęblin and Chełm. The maximum results of PDOP amounted to 1.4 in the air test in Dęblin, whereas they equaled 4.0 in the air test in Chełm. The paper also shows how the EGNOS system improved the aircraft position in relation to the only GPS solution. In this context, the EGNOS system improved the aircraft position from about 78% to 95% for each ellipsoidal coordinate axis.

Download Full-text

GNSS Multipath Detection Using Continuous Time-Series C/N0

Sensors ◽

10.3390/s20144059 ◽

2020 ◽

Vol 20 (14) ◽

pp. 4059

Author(s):

Nobuaki Kubo ◽

Kaito Kobayashi ◽

Rei Furukawa

Keyword(s):

Time Series ◽

Continuous Time ◽

Urban Areas ◽

Satellite System ◽

Line Of Sight ◽

Static Tests ◽

Gnss Receivers ◽

Multipath Detection ◽

Global Navigation Satellite ◽

Multipath Errors

The reduction of multipath errors is a significant challenge in the Global Navigation Satellite System (GNSS), especially when receiving non-line-of-sight (NLOS) signals. However, selecting line-of-sight (LOS) satellites correctly is still a difficult task in dense urban areas, even with the latest GNSS receivers. This study demonstrates a new method of utilization of C/N0 of the GNSS to detect NLOS signals. The elevation-dependent threshold of the C/N0 setting may be effective in mitigating multipath errors. However, the C/N0 fluctuation affected by NLOS signals is quite large. If the C/N0 is over the threshold, the satellite is used for positioning even if it is still affected by the NLOS signal, which causes the positioning error to jump easily. To overcome this issue, we focused on the value of continuous time-series C/N0 for a certain period. If the C/N0 of the satellite was less than the determined threshold, the satellite was not used for positioning for a certain period, even if the C/N0 recovered over the threshold. Three static tests were conducted at challenging locations near high-rise buildings in Tokyo. The results proved that our method could substantially mitigate multipath errors in differential GNSS by appropriately removing the NLOS signals. Therefore, the performance of real-time kinematic GNSS was significantly improved.

Download Full-text

Application of Least Squares with Conditional Equations Method for Railway Track Inventory Using GNSS Observations

Sensors ◽

10.3390/s20174948 ◽

2020 ◽

Vol 20 (17) ◽

pp. 4948

Author(s):

Krzysztof Czaplewski ◽

Zbigniew Wisniewski ◽

Cezary Specht ◽

Andrzej Wilk ◽

Wladyslaw Koc ◽

...

Keyword(s):

Measurement Data ◽

Satellite System ◽

Theoretical Description ◽

Railway Track ◽

Land Surveying ◽

Gnss Receivers ◽

Mobile Satellite ◽

Global Navigation Satellite ◽

Gnss Observations ◽

Observation Results

Satellite geodetic networks are commonly used in surveying tasks, but they can also be used in mobile surveys. Mobile satellite surveys can be used for trackage inventory, diagnostics and design. The combination of modern technological solutions with the adaptation of research methods known in other fields of science offers an opportunity to acquire highly accurate solutions for railway track inventory. This article presents the effects of work carried out using a mobile surveying platform on which Global Navigation Satellite System (GNSS) receivers were mounted. The satellite observations (surveys) obtained were aligned using one of the methods known from classical land surveying. The records obtained during the surveying campaign on a 246th km railway track section were subjected to alignment. This article provides a description of the surveying campaign necessary to obtain measurement data and a theoretical description of the method employed to align observation results as well as their visualisation.

Download Full-text

Testing Multi-Frequency Low-Cost GNSS Receivers for Geodetic Monitoring Purposes

Sensors ◽

10.3390/s20164375 ◽

2020 ◽

Vol 20 (16) ◽

pp. 4375

Author(s):

Veton Hamza ◽

Bojan Stopar ◽

Tomaž Ambrožič ◽

Goran Turk ◽

Oskar Sterle

Keyword(s):

Low Cost ◽

Base Point ◽

Satellite System ◽

Gnss Receivers ◽

The Difference ◽

Short Baselines ◽

Height Component ◽

Global Navigation Satellite ◽

High Level ◽

Positional Precision

Global Navigation Satellite System (GNSS) technology is widely used for geodetic monitoring purposes. However, in cases where a higher risk of receiver damage is expected, geodetic GNSS receivers may be considered too expensive to be used. As an alternative, low-cost GNSS receivers that are cheap, light, and prove to be of adequate quality over short baselines, are considered. The main goal of this research is to evaluate the positional precision of a multi-frequency low-cost instrument, namely, ZED-F9P with u-blox ANN-MB-00 antenna, and to investigate its potential for displacement detection. We determined the positional precision within static survey, and the displacement detection within dynamic survey. In both cases, two baselines were set, with the same rover point equipped with a low-cost GNSS instrument. The base point of the first baseline was observed with a geodetic GNSS instrument, whereas the second baseline was observed with a low-cost GNSS instrument. The results from static survey for both baselines showed comparable results for horizontal components; the precision was on a level of 2 mm or better. For the height component, the results show a better performance of low-cost instruments. This may be a consequence of unknown antenna calibration parameters for low-cost GNSS antenna, while statistically significant coordinates of rover points were obtained from both baselines. The difference was again more significant in the height component. For the displacement detection, a device was used that imposes controlled movements with sub-millimeter accuracy. Results, obtained on a basis of 30-min sessions, show that low-cost GNSS instruments can detect displacements from 10 mm upwards with a high level of reliability. On the other hand, low-cost instruments performed slightly worse as far as accuracy is concerned.

Download Full-text

RTK GNSS-Assisted Terrestrial SfM Photogrammetry without GCP: Application to Coastal Morphodynamics Monitoring

Remote Sensing ◽

10.3390/rs12111889 ◽

2020 ◽

Vol 12 (11) ◽

pp. 1889 ◽

Cited By ~ 3

Author(s):

Marion Jaud ◽

Stéphane Bertin ◽

Mickaël Beauverger ◽

Emmanuel Augereau ◽

Christophe Delacourt

Keyword(s):

Standard Deviation ◽

Low Cost ◽

Laser Scanner ◽

Satellite System ◽

Mean Error ◽

Ground Control Points ◽

Participatory Science ◽

Gnss Network ◽

Global Navigation Satellite

The present article describes a new and efficient method of Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS) assisted terrestrial Structure-from-Motion (SfM) photogrammetry without the need for Ground Control Points (GCPs). The system only requires a simple frame that mechanically connects a RTK GNSS antenna to the camera. The system is low cost, easy to transport, and offers high autonomy. Furthermore, not requiring GCPs enables saving time during the in situ acquisition and during data processing. The method is tested for coastal cliff monitoring, using both a Reflex camera and a Smartphone camera. The quality of the reconstructions is assessed by comparison to a synchronous Terrestrial Laser Scanner (TLS) acquisition. The results are highly satisfying with a mean error of 0.3 cm and a standard deviation of 4.7 cm obtained with the Nikon D800 Reflex camera and, respectively, a mean error of 0.2 cm and a standard deviation of 3.8 cm obtained with the Huawei Y5 Smartphone camera. This method will be particularly interesting when simplicity, portability, and autonomy are desirable. In the future, it would be transposable to participatory science programs, while using an open RTK GNSS network.

Download Full-text

CORS ARCHITECTURE AND EVALUATION OF POSITIONING BY LOW-COST GNSS RECEIVER

Geodesy and Cartography ◽

10.3846/gac.2018.1255 ◽

2018 ◽

Vol 44 (2) ◽

pp. 36-44 ◽

Cited By ~ 5

Author(s):

Massimiliano Pepe

Keyword(s):

Low Cost ◽

Satellite System ◽

Ease Of Use ◽

Quality Data ◽

Gnss Receiver ◽

Stop And Go ◽

Gnss Receivers ◽

Spatial Positioning ◽

Global Navigation Satellite

In recent years, the use of low cost GNSS receivers is becoming widespread due to their increasing performance in the spatial positioning, flexibility, ease of use and really interesting price. In addition, a recent technique of Global Navigation Satellite System (GNSS) survey, called Network Real Time Kinematic (NRTK), allows to obtain to rapid and accurate positioning measurements. The main feature of this approach is to use the raw measurements obtained and stored from a network of Continuously Operating Reference Stations (CORS) in order to generate more reliable error models that can mitigate the distance-dependent errors within the area covered by the CORS. Also, considering the huge potential of this GNSS positioning system, the purpose of this paper is to analyze and investigate the performance of the NTRK approach using a low cost GNSS receiver, in stop-and-go kinematic technique. By several case studies it was shown that, using a low cost RTK board for Arduino environment, a smartphone with open source application for Android and the availability of data correction from CORS service, a quick and accurate positioning can be obtained. Because the measures obtained in this way are quite noisy and, more in general, increasing with the baseline, by a simple and suitable statistic treatment, it was possible to increase the quality of the measure. In this way, this low cost architecture could be applied in many geomatics fields. In addition to presenting the main aspects of the NTRK infrastructure and a review of several types of correction, a general workflow in order to obtain quality data in NRTK mode, regardless of the type of GNSS receiver (multi constellations, single or many frequencies, etc.) is discussed.

Download Full-text

Preliminary validation of refractivity from a new radio occultation sounder GNOS/FY-3C

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-8-9009-2015 ◽

2015 ◽

Vol 8 (9) ◽

pp. 9009-9044 ◽

Cited By ~ 2

Author(s):

M. Liao ◽

P. Zhang ◽

G. L. Yang ◽

Y. M. Bi ◽

Y. Liu ◽

...

Keyword(s):

Standard Deviation ◽

Radio Occultation ◽

Weather Prediction ◽

Satellite System ◽

Navigation Satellite ◽

Near Surface ◽

Vertical Range ◽

New Radio ◽

Atmospheric Sounding ◽

Global Navigation Satellite

Abstract. As a new member of space-based radio occultation sounder, the GNOS (Global Navigation Satellite System Occultation Sounder) mounted on FY-3C has been carrying out the atmospheric sounding since 23 September 2013. GNOS takes a daily measurement up to 800 times with GPS (Global Position System) and Chinese BDS (BeiDou navigation satellite) signals. The refractivity profiles from GNOS are compared with the co-located ECMWF (European Centre for Medium-Range Weather Forecasts) analyses in this paper. Bias and standard deviation have being calculated as the function of altitude. The mean bias is about 0.2 % from the near surface to 35 km. The average standard deviation is within 2 % while it is down to about 1 % in the range 5–30 km where best soundings are usually made. To evaluate the performance of GNOS, COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) and GRAS/METOP-A (GNSS Receiver for Atmospheric Sounding) data are also compared to ECMWF analyses as the reference. The results show that GNOS/FY-3C meets the requirements of the design well. It possesses a sounding capability similar to COSMIC and GRAS in the vertical range of 0–30 km, though it needs improvement in higher altitude. Generally, it provides a new data source for global NWP (numerical weather prediction) community.

Download Full-text

GEOMATIC METHODS APPLIED TO THE CHANGE STUDY OF THE LA PAÚL ROCK GLACIER, SPANISH PYRENEES

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-2-w13-1771-2019 ◽

2019 ◽

Vol XLII-2/W13 ◽

pp. 1771-1775

Author(s):

A. Martínez-Fernández ◽

E. Serrano ◽

J. J. Sanjosé ◽

M. Gómez-Lende ◽

A. Pisabarro ◽

...

Keyword(s):

Laser Scanning ◽

Satellite System ◽

Ice Age ◽

Rock Glacier ◽

Glacier Surface ◽

The North ◽

Spanish Pyrenees ◽

Gnss Receivers ◽

Rock Glaciers ◽

Global Navigation Satellite

Abstract. Rock glaciers are one of the most important features of the mountain permafrost in the Pyrenees. La Paúl is an active rock glacier located in the north face of the Posets massif in the La Paúl glacier cirque (Spanish Pyrenees). This study presents the preliminary results of the La Paúl rock glacier monitoring works carried out through two geomatic technologies since 2013: Global Navigation Satellite System (GNSS) receivers and Terrestrial Laser Scanning (TLS) devices. Displacements measured on the rock glacier surface have demonstrated both the activity of the rock glacier and the utility of this equipment for the rock glaciers dynamic analysis. The glacier has exhibited the fastest displacements on its west side (over 35&thinsp;cm&thinsp;yr&minus;1), affected by the Little Ice Age, and frontal area (over 25&thinsp;cm&thinsp;yr&minus;1). As an indicator of permafrost in marginal environments and its peculiar morphology, La Paúl rock glacier encourages a more prolonged study and to the application of more geomatic techniques for its detailed analysis.

Download Full-text

RECEPTORES DE SINAIS DO SISTEMA GLOBAL DE NAVEGAÇÃO POR SATÉLITE SUBMETIDOS A INTERFERÊNCIAS FÍSICAS

ENERGIA NA AGRICULTURA ◽

10.17224/energagric.2020v35n1p115-125 ◽

2020 ◽

Vol 35 (1) ◽

pp. 115-125

Author(s):

João Luiz Jacintho ◽

Gabriel Araújo e Silva Ferraz ◽

Lucas Santos Santana ◽

Patrícia Ferreira Ponciano Ferraz

Keyword(s):

Minimal Medium ◽

Satellite System ◽

Control Points ◽

Satellite Navigation System ◽

Accuracy And Precision ◽

Agricultural Applications ◽

Gnss Receivers ◽

Survey Accuracy ◽

Global Navigation Satellite ◽

Interference Minimum

RECEPTORES DE SINAIS DO SISTEMA GLOBAL DE NAVEGAÇÃO POR SATÉLITE SUBMETIDOS A INTERFERÊNCIAS FÍSICAS JOÃO LUIZ JACINTHO1, GABRIEL ARAÚJO E SILVA FERRAZ2, LUCAS SANTOS SANTANA3, PATRÍCIA FERREIRA PONCIANO FERRAZ4 1 Instituto Federal do Norte de Minas Gerais - IFNMG, Campus Araçuaí BR 367, km 278, s/n - Zona Rural, 39600-000, Araçuaí - MG, Brasil. [email protected]. 2 Departamento de Engenharia Agrícola, Universidade Federal de Lavras – UFLA, Aquenta Sol, 3037, 37200900, Lavras - MG, Brasil. [email protected]. 3Departamento de Engenharia Agrícola, Universidade Federal de Lavras – UFLA, Aquenta Sol, 3037, 37200900, Lavras - MG, Brasil. [email protected]. 4 Departamento de Engenharia Agrícola, Universidade Federal de Lavras – UFLA, Aquenta Sol, 3037, 37200900, Lavras - MG, Brasil. [email protected]. RESUMO: Incertezas são encontradas em trabalhos com receptores do Sistemas Global de Navegação por Satélite GNSS. Diante disso, objetivou-se com este estudo investigar a influência de obstáculos físicos nos erros de acurácia e precisão em levantamentos com receptores GNSS e suas aplicações agrícolas. Foram implantados quatros pontos de controle rastreados no modo estático (base) e oito pontos de estudos rastreados no modo cinemático em tempo real (RTK) e Estático Rápido (ER), utilizando um par de receptores GNSS e um par de receptores GNSS-RTK. Os níveis de acurácia e precisão foram avaliados em oito pontos obtidos por rastreios do tipo ER e RTK. Combinados com quatro bases fixas, alocados de três formas: mínima, média e alta interferência física. Pontos provenientes do levantamento RTK, apresentaram diferenças na ordem de milímetros a centímetros, quando comparados às coordenadas obtidas do levantamento (ER). Para os níveis de obstrução, a mínima interferência apresentou erro dentro dos limites estipulados pelo equipamento, a máxima interferência apresentou menor acurácia. O efeito do multipercurso do sinal foi o fator mais determinante para a redução da acurácia das coordenadas dos pontos. Recomenda-se a aplicação do levantamento RTK para trabalhos onde a precisão das coordenadas seja mais relevante que a acurácia. Palavras-chaves: Geodésia, levantamento planialtimétrico, acurácia, precisão. GLOBAL SATELLITE NAVIGATION SYSTEM RECEIVERS SUBMITTED TO PHYSICAL INTERFERENCES ABSTRACT: Uncertainties are found in works with Global Navigation Satellite System receivers (GNSS). Therefore, this study aimed to investigate influence physical obstacles on accuracy and precision errors in surveys with GNSS receivers and their agricultural applications. Four control points tracked in static (base) mode and eight study points tracked in a kinematic mode in real-time (RTK) and Fast Static (ER) were implemented, using a pair of GNSS receivers and pair of GNSS-RTK receivers. Accuracy levels and precision were evaluated at eight points obtained by ER and RTK, combined with four fixed bases, allocated in three ways: minimal, medium and high physical interference. RTK survey points showed differences order millimeters to centimeters when compared to the survey (ER) coordinates. The obstruction levels, interference minimum, had an error within limits stipulated by equipment, interference maximum showed low accuracy. RTK survey is recommended for jobs where the coordinate precision is more relevant than accuracy. Keywords: Geodesy, planialtimetric survey, accuracy, precision.

Download Full-text