European Geostationary Navigation Overlay Service Research Articles

Optimal Global Positioning System/European Geostationary Navigation Overlay Service Positioning Model Using Smartphone

The potential for the use of smartphones in GNSSs (Global Navigation Satellite Systems) positioning has increased in recent years due to the emergence of the ability of Android-based devices used to process raw satellite data. This paper presents the results of a study on the use of SBAS data transmitted by the EGNOS (European Geostationary Navigation Overlay Service) system in GNSS positioning using a Xiaomi Mi8 smartphone. Raw data recorded at a fixed point were used in post-processing calculations in GPS/EGNOS positioning by determining the coordinates for every second of a session of about 5 h and comparing the results to those obtained with a Septentrio AsteRx2 GNSS receiver operating at the same time at a distance of about 3 m. The calculations were performed using the assumptions of the GNSS/SBAS positioning algorithms, which were modified with carrier-phase smoothed code observations and the content of the corrections transmitted by EGNOS.

Review of the Monothematic Series of Publications Concerning Research on Statistical Distributions of Navigation Positioning System Errors

This review presents the main results of the author’s study, obtained as part of the post-doctoral (habilitation) dissertation entitled “Research on Statistical Distributions of Navigation Positioning System Errors”, which constitutes a series of five thematically linked scientific publications. The main scientific aim of this series is to answer the question of what statistical distributions follow the position errors of navigation systems, such as Differential Global Positioning System (DGPS), European Geostationary Navigation Overlay Service (EGNOS), Global Positioning System (GPS), and others. All of the positioning systems under study (Decca Navigator, DGPS, EGNOS, and GPS) are characterised by the Position Random Walk (PRW), which means that latitude and longitude errors do not appear randomly, being a feature of the normal distribution. The research showed that the Gaussian distribution is not an optimal distribution for the modelling of navigation positioning system errors. A higher fit to the 1D and 2D position errors was exhibited by such distributions as beta, gamma, and lognormal. Moreover, it was proven that the Twice the Distance Root Mean Square (2DRMS(2D)) measure, which assumes a priori normal distribution of position errors in relation to latitude and latitude, was smaller by 10–14% than the position error value from which 95% fixes were smaller (it is known as the R95(2D) measure).

MLP-based user-applicable method for SBAS GIVD calibration: A comparative study based on CODE final GIM products

Satellite-Based Augmentation Systems (SBASs) are designed to enhance the performance of Global Navigation Satellite Systems (GNSSs) for civil aviation users. As SBAS Geostationary Earth Orbit (GEO) satellite signals are received in a wide area, far more non-aeronautical GNSS users utilize SBAS to improve navigation performance. Since ionospheric delay is the principal error source of GNSS and a leading correction aspect of SBAS, the GEO-broadcast ionospheric data quality of six SBASs over the past three years is assessed in this article. Results show that European Geostationary Navigation Overlay Service (EGNOS), System for Differential Correction and Monitoring (SDCM), and Wide-Area Augmentation System (WAAS) have the highest Grid Ionospheric Vertical Delay (GIVD) accuracy judged by the residual Standard Deviation (STD), then followed by BeiDou SBAS (BDSBAS) and Multi-functional Satellite Augmentation System (MSAS), while GPS-Aided GEO Augmented Navigation (GAGAN) is the worst. The 6 m Grid Ionospheric Vertical Error (GIVE) availability is over 90 percent of the time for most Ionospheric Grid Points (IGPs) of all tested SBASs. However, GAGAN and WAAS have a significant availability decline at 3 m GIVE. In addition, the integrity limits of MSAS and WAAS are fairly conservative. In contrast, the confidence bounds of BDSBAS and SDCM are excessively radical that fail to meet the integrity requirement. To improve the ionospheric data quality received from SBAS, a Multi-Layer Perceptron (MLP)-based user-applicable GIVD calibration method is proposed in the article. A well-trained MLP learned temporal and spatial correlations of the IGP delays and extracted transfer functions between broadcast and reference GIVDs to eliminate error. The SBAS processing errors in Differential Code Bias (DCB) compensation, GIVD estimation modeling, and GEO message quantization are rectified by the MLP trained by abundant historical data with Center for Orbit Determination in Europe (CODE) final Global Ionospheric Maps (GIMs) as reference. Test results on real-time data show that over 85 percent IGPs have STD decline after calibration. The STD declination rates of six SBASs except for SDCM are over 15 percent, and the Mean Absolute Error (MAE) and Root Mean Square Error (RMS) calibration effects are dramatic for all systems. Finally, the average GIVEs are reduced by more than 50 percent for EGNOS, GAGAN, MSAS, and WAAS with a 99.9 percent integrity level maintained. Despite no promotion on availability for BDSBAS and SDCM, the proposed method compensates for the integrity issues of the systems.

GNSS integrity risk evaluation in the position domain based on the generalized Pareto distribution

Integrity monitoring of global navigation satellite systems (GNSSs) is designed to protect against extremely rare hazardous events, characterized by an integrity risk with a very low probability. The traditional integrity risk evaluation is restricted simultaneously by non-Gaussian measurement errors and impractical time consumption. Based on extreme value theory, a generalized Pareto distribution (GPD)-based integrity risk evaluation method in the position domain is proposed to estimate the upper bound of the integrity risk. In order to account for the GPD modeling error and estimation error, conservatism of the proposed GPD-based integrity risk evaluation is obtained by imposing model-driven and data-driven overbounding. Simulation results from four typical heavy-tailed distributions have shown that conservative and tight bound integrity risk results can be achieved. Furthermore, real-world European Geostationary Navigation Overlay Service measurements experiment has shown that the integrity risk evaluation resulting from the proposed method is at least one order less than the traditional evaluation method, which is consistent with official publications.

Aspekty prawne europejskich systemów nawigacji satelitarnej w dobie przemian

Global Navigation Satellite System (GNSS) is an important tool in supporting innovation and developing the economy. The European Union has created two systems: Galileo and EGNOS (European Geostationary Navigation Overlay Service), which enable the localisation of points on the Earth’s surface and in the sky. The GNSS programme offers a range of opportunities for Central and Eastern European societies in which the existence of the E-GNNS (European Global Navigation Satellite System) is still not well known. The article is an attempt to raise awareness of the use of Galileo and EGNOS systems, as well as to present the legal framework concerning this programme and the changes introduced by Regulation (EU) 2021/696 of the European Parliament and of the Council of 28 April 2021. The main research goal is assessing changes in the most crucial areas of this regulation, such as security of the systems, access of third parties, compliance of the provisions with human rights standards, and issues related to budgetary implications which are particularly important for the continuity and stability of E-GNNS.

Analysis of GPS/EGNOS Positioning Quality Using Different Ionospheric Models in UAV Navigation.

Unmanned aerial vehicles (UAVs) have become very popular tools for geoinformation acquisition in recent years. They have also been applied in many other areas of life. Their navigation is highly dependent on global navigation satellite systems (GNSS). The European Geostationary Navigation Overlay Service (EGNOS) is intended to support GNSSs during positioning, mainly for aeronautical applications. The research presented in this paper concerns the analysis of the positioning quality of a modified GPS/EGNOS algorithm. The calculations focus on the source of ionospheric delay data as well as on the aspect of smoothing code observations with phase measurements. The modifications to the algorithm concerned the application of different ionospheric models for position calculation. Consideration was given to the EGNOS ionospheric model, the Klobuchar model applied to the GPS system, the Klobuchar model applied to the BeiDou system, and the NeQuick model applied to the Galileo system. The effect of removing ionospherical corrections from GPS/EGNOS positioning on the results of the determination of positioning quality was also analysed. The results showed that the original EGNOS ionospheric model maintains the best accuracy results and a better correlation between horizontal and vertical results than the other models examined. The additional use of phase-smoothing of code observations resulted in maximum horizontal errors of approximately 1.3 m and vertical errors of approximately 2.2 m. It should be noted that the results obtained have local characteristics related to the area of north-eastern Poland.

Analysis of the accuracy of EGNOS+SDCM positioning in aerial navigation

The article presents a modified scheme of determining the accuracy parameter of SBAS (Satellite Based Augmentation System) positioning with use of two supporting systems: EGNOS (European Geostationary Navigation Overlay Service) and SDCM (System of Differential Correction and Monitoring). The proposed scheme is based on the weighted mean model, which combines single solutions of EGNOS and SDCM positions in order to calculate the accuracy of position-ing of the aerial vehicle. The applied algorithm has been tested in a flight experiment conducted in 2020 in north-eastern Poland. The phase of approach to landing of a Diamond DA 20-C1 aircraft at the EPOD airport (European Poland Olsztyn Dajtki) was subjected to numerical analysis. The Septentrio AsterRx2i geodesic receiver was installed on board of the aircraft to collect and record GPS (Global Positioning System) observations to calculate the naviga-tion position of the aircraft. In addition, the EGNOS and SDCM corrections in the “*.ems” format were downloaded from the real time server data. The computations were realized in RTKPOST library of the RTKLIB v.2.4.3 software and also in Scilab application. Based on the conducted research, it was found that the accuracy of aircraft positioning from the EGNOS+SDCM solution ranged from -1.63 m to +3.35 m for the ellipsoidal coordinates BLh. Additionally, the accuracy of determination of the ellipsoidal height h was 1÷28% higher in the weighted mean model than in the arith-metic mean model. On the other hand, the accuracy of determination of the ellipsoidal height h was 1÷28% higher in the weighted mean model than for the single EGNOS solution. Additionally, the weighted mean model reduced the resultant error of the position RMS-3D by 1÷13% in comparison to the arithmetic mean model. The mathematical model used in this study proved to be effective in the analysis of the accuracy of SBAS positioning in aerial navigation

Accuracy Examination of the SDCM Augmentation System in Aerial Navigation

The paper presents a modified algorithm for determining the accuracy parameter of the system for differential corrections and monitoring (SDCM) navigation solution in air navigation. For this purpose, a solution to determine the resultant accuracy parameter was proposed by using two on-board global navigation satellite system (GNSS) receivers. The mathematical algorithm takes into account the calculation of a single point positioning accuracy for a given GNSS receiver and a weighting factor combining the position error values. The weighting factor was determined as a function of the number of tracked GNSS satellites used in the SDCM single point positioning solution. The resultant accuracy parameter was expressed in ellipsoidal coordinates BLh (B—latitude, L—longitude, h—ellipsoidal height). The study used GNSS kinematic data recorded by two on-board receivers: Trimble Alloy and Septentrio AsterRx2i, located in a Diamond DA 20-C1 aircraft. The test flight was performed near the city of Olsztyn in north-eastern Poland. Calculations and analyses were performed using RTKLIB software and the Scilab environment. On the basis of the performed tests, it was found that the proposed algorithm for SDCM system allows for improvement in the determination of the resultant accuracy value by 56–80% in relation to the results of position errors from a single GNSS receiver. Additionally, the proposed algorithm was tested for the European Geostationary Navigation Overlay Service (EGNOS) system, and in this case, the improvement in the accuracy parameter was even better and was in the range of 69–89%. The resulting SDCM and EGNOS positioning accuracy met the International Civil Aviation Organization (ICAO) certification requirements for SBAS systems in air navigation. The mathematical algorithm developed in this work was tested positively and can be implemented within the SBAS augmentation system in air navigation.

Application of the SBAS/EGNOS positioning method to determine UAV coordinates

Abstract: The article presents the results of research on determining the UAV (Unmanned Aerial Vehicle) position using the SBAS (Satellite Based Augmentation System) positioning method for the EGNOS (European Geostationary Navigation Overlay Service) support system. The experiment used a single-frequency AsteRx-m2 UAS receiver, which recorded GPS (Global Positioning System) satellite observations and EGNOS corrections. The test flight was performed in 2020 near Warsaw. Navigational calculations for determining the position of the UAV during the flight were made in the gLAB v.5.5.1 software. Based on the performed calculations, the following were determined: BSP coordinates in the ellipsoidal system BLh, mean errors of BSP coordinates, and values of DOP (Dilution of Precision) geometric coefficients. In addition, during the calculations, it was found that the mean error values of the determined BSP coordinates do not exceed 3.6 m, and the maximum value of the geometric coefficient GDOP (Geometric DOP) is less than 3.5. Keywords: SBAS, EGNOS, BSP, mean errors, DOP

Designation of the Quality of EGNOS+SDCM Satellite Positioning in the Approach to Landing Procedure

The main aim of this paper is to present the results of research on the application of a modified mathematical model to determine the quality parameters of SBAS (Satellite Based Augmentation System) satellite positioning in aviation. The authors developed a new calculation strategy to determine the resultant values of the parameters of accuracy, continuity, availability and integrity of SBAS positioning. To achieve it, a weighted mean model was used for the purposes of developing a mathematical algorithm to determine the resultant values of SBAS positioning. The created algorithm was implemented for two SBAS supporting systems, i.e., EGNOS (European Geostationary Navigation Overlay Service) and SDCM (System of Differential Correction and Monitoring). The algorithm was tested in a flight test conducted with a Diamond DA 20-C airplane in north-eastern Poland in 2020. The conducted research revealed that the resultant error of the position in 3D space determined with use of the proposed weighted mean model improved by, respectively, 1–7% in comparison to the standard arithmetic mean model and by 1–37% in comparison to a single SBAS/EGNOS solution. Moreover, the application of the Multi-SBAS positioning algorithm results in an increase in the nominal results of continuity and availability by 50% in comparison to the arithmetic mean model. Apart from that, the values of the integrity parameters determined with use of the proposed weighted mean model improved by 62–63% in comparison to the standard arithmetic mean model.

Determination of Navigation System Positioning Accuracy Using the Reliability Method Based on Real Measurements

In navigation, the Twice the Distance Root Mean Square (2DRMS) is commonly used as a position accuracy measure. Its determination, based on statistical methods, assumes that the position errors are normally distributed and are often not reflected in actual measurements. As a result of the widespread adoption of this measure, the positioning accuracy of navigation systems is overestimated by 10–15%. In this paper, a new method is presented for determining the navigation system positioning accuracy based on a reliability model where the system’s operation and failure statistics are referred to as life and failure times. Based on real measurements, the method proposed in this article will be compared with the classical method (based on the 2DRMS measure). Real (empirical) measurements made by the principal modern navigation positioning systems were used in the analyses: Global Positioning System (GPS) (168’286 fixes), Differential Global Positioning System (DGPS) (900’000 fixes) and European Geostationary Navigation Overlay Service (EGNOS) (900’000 fixes). Research performed on real data, many of which can be considered representative, have shown that the reliability method provides a better (compared to the 2DRMS measure) estimate of navigation system positioning accuracy. Thanks to its application, it is possible to determine the position error distribution of the navigation system more precisely when compared to the classical method, as well as to indicate those applications that can be used by this system, ensuring the safety of the navigation process.

SIMULATION OF EGNOS SATELLITE NAVIGATION SIGNAL USAGE FOR AIRCRAFT LPV PRECISION INSTRUMENT APPROACH

Satellite navigation has become a very important topic in the air transport industry along with its application in instrument approach procedures. Recently, extracted statistical characteristics of the European Geostationary Navigation Overlay Service (EGNOS) satellite signal have been made available from real measurements in the Czech Republic. The numerical modeling approach is taken for a feasibility study of automatic aircraft control during the Localizer Performance with Vertical Guidance (LPV) precision approach based on such navigation data. The model incorporates Kalman filtering of the stochastic navigation signal, feed-back control of L-410 aircraft dynamics and the calculation of approach progress along the predefined procedure. Evaluation of the performance of the system prototype is performed using the scenarios developed with a strong interest in altitude control. The specific scenario is focused on a curved approach which offers a huge advantage of the approaches based on the Satellite-based Augmentation System (SBAS) compared to ones with the Instrument Landing System (ILS). Outputs of simulation executions are statistically analyzed and assessed against predefined navigation performance goals equivalent to ILS categories with a positive outcome.

Improvement of UAV Positioning Performance Based on EGNOS+SDCM Solution

The article presents the results of research on multi-SBAS (multi-satellite-based augmentation system) positioning in UAV (unmanned aerial vehicle) technology. For this purpose, a new solution was developed for combining the UAV position navigation solution from several SBAS systems. In this particular case, the presented linear combination algorithm is based on the fusion of EGNOS (European geostationary navigation overlay service) and SDCM (system of differential correction and monitoring) positioning to determine the resultant UAV coordinates. The algorithm of the mathematical model uses weights of measurements in three ways, i.e., Variant I, the reciprocal of the number of tracked satellites from a single SBAS solution; Variant II, the inverse square of mean coordinate errors from a single SBAS solution; and Variant III, the reciprocal of UAV flight speed from a single SBAS solution. The research experiment used real GNSS (global navigation satellite system) navigation data recorded by the VTOL unmanned platform. The test flight was made in April 2020 in Poland, near Warsaw. Based on the developed research results, it was found that the highest accuracy of UAV positioning was obtained when using the weighting model for Variant II. In the weight model of Variant II, the accuracy of the solution of the UAV position increased by 1–2% for the horizontal components and 19–22% for the vertical component h, concerning the results obtained from the weighing Variants I and III. It is worth noting that the proposed research model significantly improves the results of determining the ellipsoidal height h. Compared to the arithmetic mean model, determining the h component in the Variant II weight model is improved by about 23%. The paper also shows the advantage of EGNOS+SDCM positioning over EGNOS positioning alone in determining the accuracy of the vertical component h. The obtained research results show the significant advantages of the multi-SBAS positioning model in UAV technology.

The GPS / EGNOS Positioning Quality in APV-1 and LPV-200 flight procedures

Accuracy, integrity, continuity and availability are the basic quality parameters extremely important in satellite navigation. The article presents results of research using the European Geostationary Navigation Overlay Service (EGNOS) that belongs to the group of Satellite Based Augmentation Systems (SBAS). The measurement data adopted for analysis were recorded in years: 2012, 2014, 2015, 2017 and 2018 in the north-eastern Poland. Results of the analysis showed a significant reduction in the maximum GPS / EGNOS positioning error values from 2014 onwards (compared to results from 2012). In general, values of parameters characterizing accuracy, integrity and availability meet the requirements for EGNOS applications in APV-1 and LPV-200 aviation procedures. It the case of continuity the requirements are not met.

Application the SBAS/EGNOS Corrections in UAV Positioning

The paper presents a new concept of determining the resultant position of a UAV (Unmanned Aerial Vehicle) based on individual SBAS (Satellite-Based Augmentation System) determinations from all available EGNOS (European Geostationary Navigation Overlay Service) satellites for the SPP (Single Point Positioning) code method. To achieve this, the authors propose a weighted mean model to integrate EGNOS data. The weighted model was based on the inverse of the square of the mean position error along the component axes of the BLh ellipsoidal frame. The calculations included navigation data from the EGNOS S123, S126, S136 satellites. In turn, the resultant UAV position model was determined using the Scilab v.6.0.0 software. Based on the proposed computational strategy, the mean values of the UAV BLh coordinates’ standard deviation were better than 0.2 m (e.g., 0.0000018° = 0.01″ in angular measurement). Additionally, the numerical solution used made it possible to increase the UAV’s position accuracy by about 29% for Latitude, 46% for Longitude and 72% for ellipsoidal height compared to the standard SPP positioning in the GPS receiver. It is also worth noting that the standard deviation of the UAV position calculated from the weighted mean model improved by about 21 ÷ 50% compared to the arithmetic mean model’s solution. It can be concluded that the proposed research method allows for a significant improvement in the accuracy of UAV positioning with the use of EGNOS augmentation systems.

EGNOS Performance Along Finnish Coast

The purpose of this article is to demonstrate the benefits of EGNOS (European Geostationary Navigation Overlay Service / SBAS in Europe) for the community and inform about the activities that are ongoing for the provision of EGNOS L1 maritime service. EC (European Commission) and GSA (European GNSS Agency) are assessing an EGNOS L1 maritime service with the objective to complement the existing maritime radio-navigation systems (e.g. DGNSS). community is interested in using SBAS for ocean waters, coastal waters and harbour entrances/approaches considering operational needs (IMO Res. 1046), especially where there is no back-up infrastructure or in poorly covered environments. EGNOS L1 Service aims at providing pseudo-range corrections and alert information to the GPS L1 signals for maritime navigation, obtaining enhanced accuracy and ranging integrity information over Europe. In order to ensure a safe use of SBAS by all shipborne receivers, an IEC 61108 standard for SBAS receiver equipment should be published. IEC 61108 is a collection of IEC standards for Maritime navigation and radio-communication equipment and systems - Global navigation satellite systems (GNSS). In consequence, EC, GSA, ESA and ESSP are developing guidelines for manufacturers for the implementation of SBAS in shipborne receivers to be compliant with the operational requirements defined in International Organization (IMO) Resolution A.1046. These guidelines, together with a set of test specifications, intend to support the integration of SBAS in the standardisation process for maritime navigation and radio-communication equipment and systems within IEC framework. One GNSS campaign will be performed along the Finnish coast in order to analyse the EGNOS performance in the border of Northeast EGNOS coverage area. Different types of receivers configured to use SBAS will be on board the vessel to analyse the results. The set of receivers to be used would include maritime receivers, high-end receivers and also new receivers aligned with the future SBAS guidelines. On one side, the EGNOS navigation errors will be obtained with respect to a reference PPP post-processed trajectory. On the other side, the EGNOS availability will be obtained, taking especial attention at the border service coverage area. The EGNOS performance results will be compared with respect to the GPS standalone solution, to verify EGNOS provides an enhanced navigation position. The performance obtained with the receivers will be compared with the operational requirements defined in the IMO Resolution A.1046 (27) to assess the feasibility of EGNOS for some maritime applications. Finally, a deep performance analysis will be done in the Northeast border of EGNOS coverage area for ocean waters, coastal waters and harbour entrances/approaches. Based on the results obtained from a receiver, it will be shown a reliable EGNOS navigation solution with better accuracy than GPS standalone solution. The results aim at confirming that EGNOS L1 service is compliant with the operational requirements defined in the IMO Res. A.1046 (27) for ocean waters, coastal waters and harbour entrances/approaches, being beneficial for maritime community.

Consistency of the Empirical Distributions of Navigation Positioning System Errors with Theoretical Distributions-Comparative Analysis of the DGPS and EGNOS Systems in the Years 2006 and 2014.

Positioning systems are used to determine position coordinates in navigation (air, land and marine). The accuracy of an object’s position is described by the position error and a statistical analysis can determine its measures, which usually include: Root Mean Square (RMS), twice the Distance Root Mean Square (2DRMS), Circular Error Probable (CEP) and Spherical Probable Error (SEP). It is commonly assumed in navigation that position errors are random and that their distribution are consistent with the normal distribution. This assumption is based on the popularity of the Gauss distribution in science, the simplicity of calculating RMS values for 68% and 95% probabilities, as well as the intuitive perception of randomness in the statistics which this distribution reflects. It should be noted, however, that the necessary conditions for a random variable to be normally distributed include the independence of measurements and identical conditions of their realisation, which is not the case in the iterative method of determining successive positions, the filtration of coordinates or the dependence of the position error on meteorological conditions. In the preface to this publication, examples are provided which indicate that position errors in some navigation systems may not be consistent with the normal distribution. The subsequent section describes basic statistical tests for assessing the fit between the empirical and theoretical distributions (Anderson-Darling, chi-square and Kolmogorov-Smirnov). Next, statistical tests of the position error distributions of very long Differential Global Positioning System (DGPS) and European Geostationary Navigation Overlay Service (EGNOS) campaigns from different years (2006 and 2014) were performed with the number of measurements per session being 900’000 fixes. In addition, the paper discusses selected statistical distributions that fit the empirical measurement results better than the normal distribution. Research has shown that normal distribution is not the optimal statistical distribution to describe position errors of navigation systems. The distributions that describe navigation positioning system errors more accurately include: beta, gamma, logistic and lognormal distributions.

Statistical Distribution Analysis of Navigation Positioning System Errors-Issue of the Empirical Sample Size.

Positioning systems are used to determine position coordinates in navigation (air, land, and marine). Statistical analysis of their accuracy assumes that the position errors (latitude—δφ and longitude—δλ) are random and that their distributions are consistent with the normal distribution. However, in practice, these errors do not appear in a random way, since the position determination in navigation systems is done with an iterative method. It causes so-called “Position Random Walk”, similar to the term “Random Walk” known from statistics. It results in the empirical distribution of δφ and δλ being inconsistent with the normal distribution, even for samples of up to several thousand measurements. This phenomenon results in a significant overestimation of the accuracy of position determination calculated from such a short series of measurements, causing these tests to lose their representativeness. This paper attempts to determine the length of a measurement session (number of measurements) that is representative of the positioning system. This will be a measurement session of such a length that the position error statistics (δφ and δλ) represented by the standard deviation values are close to the real values and the calculated mean values ( and ) are also close to the real values. Special attention will also be paid to the selection of an appropriate (statistically reliable) number of measurements to be tested statistically to verify the hypothesis that the δφ and δλ distributions are consistent with the normal distribution. Empirical measurement data are taken from different positioning systems: Global Positioning System (GPS) (168′286 fixes), Differential Global Positioning System (DGPS) (864′000 fixes), European Geostationary Navigation Overlay Service (EGNOS) (928′492 fixes), and Decca Navigator system (4052 fixes). The analyses showed that all researched positioning systems (GPS, DGPS, EGNOS and Decca Navigator) are characterized by the Position Random Walk (PRW), which resulted in that the empirical distribution of δφ and δλ being inconsistent with the normal distribution. The size of the PRW depends on the nominal accuracy of position determination by the system. It was found that measurement sessions consisting of 1000 fixes (for the GPS system) overestimate the accuracy analysis results by 109.1% and cannot be considered representative. Furthermore, when analyzing the results of long measurement campaigns (GPS and DGPS), it was found that the representative length of the measurement session differs for each positioning system and should be determined for each of them individually.

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

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.

SBAS Guidelines for Shipborne Receiver: EGNOS Performance Based on IMO Res. A.1046 (27)

Abstract The European Geostationary Navigation Overlay Service (EGNOS) augments the open public service offered by the GPS in Europe making suitable the use of GPS for safety critical applications. EGNOS is designed according to the same standard [ICAO SARPs, 2018] such as US WAAS, Japanese MSAS, GAGAN in India, SDCM in Russia and KAAS in South Korea and provides over Europe both corrections and integrity information about the GPS system. As the European SBAS, EGNOS offers three services: Open Service, Safety-of-life Service and EDAS. In general, the EGNOS Safety-of-life (SoL) Service is intended for transport applications in different domains (and currently in use by Aviation) where lives could be endangered if the performance of the navigation system is degraded below specific accuracy limits without giving notice in the specified time to alert. This requires that the relevant authority of the particular transport domain determines specific requirements for the navigation service based on the needs of that domain. Even if the main objective of the SBAS systems is the civil aviation community, the advantages provided by this technology are very useful to users from other domains. In this sense, a new EGNOS service for maritime is currently under development with the objective to complement the existing maritime radionavigation systems (e.g. DGNSS) in the European region for enhanced accuracy and integrity information where there is no backup infrastructure or in poorly covered environments. One of the steps needed for the development of this new EGNOS maritime service is the definition of a minimum set of recommendations for receiver manufacturers to provide them with a clear view on how to design their SBAS receivers to be compliant with the requirements defined for such a service. For that, EC, GSA, ESA and ESSP SAS have been working together since 2016 to develop guidelines for manufacturers for the implementation of SBAS in shipborne receiver. These guidelines, developed in the frame of the SBAS Working Group created in the Special Committee (SC) 104 on Differential Global Navigation Satellite Systems (DGNSS) of Radio Technical Commission for Maritime Services (RTCM), define a minimum set SBAS messages to be compliant with the International Maritime Organization (IMO) Resolution A.1046 and additionally provide a test specifications. This paper presents a summary of these SBAS guidelines as well as the preliminary list of tests that must be fulfilled to be compliant. Additionally, a preliminary performance assessment of the EGNOS maritime service based on IMO Res. A.1046 (27) for a 24-months period during 2016, 2017 and 2018 is presented. The performance parameters are calculated using real data to show what level of performance was attained by EGNOS. The assessment was done using both EGNOS ground monitoring stations (RIMS) and fault-free receivers, based on these guidelines, fed with actual data. The performance is shown for each performance parameter defined in the IMO Res. A.1046 (27) and for navigation in Ocean Waters and coastal waters, harbour entrances and harbour approaches. The paper also includes Service Coverage maps representing where EGNOS maritime service based on IMO Res. A.1046 (27) is fulfilling the requirements. Furthermore, GSA and ESSP, with the collaboration of The Norwegian Coastal Administration and Hurtigruten Cruises, carried out a GNSS data collection campaign of 10 days along the Norwegian coast with a trajectory through Trondheim to Kirkenes and Kirkenes to Bergen in February 2018. The aim of this data campaign was to assess EGNOS performance at user level in the maritime domain at high latitudes in Europe. The data campaign includes the navigation outside the MT27 region defined in EGNOS at that moment (70ºN). A performance assessment of EGNOS using some commercial receivers and a software receiver in line with the SBAS guidelines will be presented, showing the observed accuracy and availably results of the EGNOS solution.