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

Abstract

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.

Comprehensive Investigation of Unmanned Aerial Vehicles (UAVs): An In-Depth Analysis of Avionics Systems

“…A precise indoor UAV location estimation can also be obtained by means of ultrasonic acoustic signals with a three-stage localization scheme [86]. Outdoor UAV navigation methods, on the other hand, mainly rely on GPS [87], Inertial Navigation System (INS) [88], Global Navigation Satellite System (GNSS) [89], integrated INS/GNSS [90], and others [91]. This manuscript, however, conducts another approach for reviewing UAV navigation techniques, namely, classified as navigation strategy, path planning/obstacle avoiding, and localization.…”

Ionospheric Error Models for Satellite-Based Navigation—Paving the Road towards LEO-PNT Solutions

“…There are several existing models in the literature that aim to mitigate ionospheric delays, such as the NeQuick, Klobuchar, BeiDou Global broadcast Ionospheric delay correction Model (BDGIM), and Quasi-4-Dimension Ionospheric Modeling (Q4DIM) models [23]. These models measure or predict the error induced by the ionosphere, depending on the user's location, time of day, and day of the year [24,25]. However, all of these models are tailored for correcting errors for GNSS signals and, therefore, cannot be directly applied to signals from LEO satellites.…”

“…Contrary to DFRs, SFRs rely on two widely used models to estimate ionospheric delay, namely the Klobuchar [23][24][25] and NeQuick [23,25] models. The first is typically used in GPS and BeiDou, while the latter is more encountered in Galileo signals.…”

“…The Klobuchar model was the first model developed to provide ionospheric correction through GPS signals. It is designed to be a computationally lightweight model while delivering a 50% decrease in the Root Mean Square (RMS) of the positioning error [23][24][25]. The algorithm, which runs on GNSS receivers, determines the ionospheric delay based on several parameters, such as the user's approximate geodetic latitude and longitude, elevation and azimuth angles of the visible satellites, and eight coefficients pα i , β i ; i " 0, .…”

Algorithms for improving the position determination of an UAV equipped with a single-frequency GPS receiver for low-altitude photogrammetry

“…How important the accuracy and integrity of UAV positioning is can be seen in the works [28][29][30], where the effects of intentional spoofing the determination of UAV position using GPS navigation systems is shown. As regards UAV positioning using GPS single-frequency receivers, it is also possible to monitor the status of the ionosphere [31] or also air pollution in the troposphere [32]. GPS singlefrequency positioning has its direct impact on photogrammetric and remote sensing applications in UAV technology.…”