Klobuchar, NeQuick G, and EGNOS Ionospheric Models for GPS/EGNOS Single-Frequency Positioning under 6–12 September 2017 Space Weather Events

Abstract

The ionosphere is one of the main factors affecting the accuracy of global navigation satellite systems (GNSS). It is a dispersive medium for radio signals, and for multi-frequency receivers, most of its effect can be removed. The problem is for the single-frequency devices, which must rely on a correction model. The motivation of this paper is the adoption of different ionospheric models in GPS/EGNOS (Global Positioning System/European Geostationary Navigation Overlay Service) positioning to mitigate the impact of geomagnetic storms. The aim of this article is to examine the accuracy of GPS/EGNOS single-frequency positioning. In all the examined solutions, GPS L1 data augmented with the EGNOS clock and ephemeris corrections were used in position calculation. The changes were only made to the ionospheric model. The examined scenarios are as follows: without any model (off), Klobuchar, NeQuick G, and EGNOS model. The analysed period is 6–12 September 2017, during which the last strong geomagnetic storm took place. In order to perform a reliable analysis, the study was conducted at three International GNSS Service (IGS) stations in different geographical latitudes, within the EGNOS APV-1 (Approach with Vertical Guidance) availability border. The obtained results prove that the EGNOS ionospheric model meets the aviation positioning accuracy criteria for the APV-1 approach during the studied geomagnetic storm. The EGNOS average horizontal positioning error of 0.75 m was on average almost two times lower than the other solutions. For vertical positioning, the EGNOS error of 0.93 m proved to be two times lower than those of the Klobuchar and NeQuick G models, while it was more than three times lower for the off solution.

On the Correlation of Solar Activity and Troposphere on the GNSS/EGNOS Integrity. Fuzzy Logic Approach

“…And this results in adverse ionospheric effects that influence signal integrity. On the other hand, high SSN is connected with a high TEC level and greater chances for intense geomagnetic storms, which, clearly, have negative effects [22]. This shows that SSN is not necessarily the best metric to be used in the context of GNSS signal integrity.…”

“…For previously selected combinations, the formula for determining the value of H k is presented below. This formula refers to the combination of K 17 and takes the form: H 17 = h 173 + h 175 = 0.079 (22) role in these studies. This is the same as solar activity.…”

Improvement of UAV Positioning Performance Based on EGNOS+SDCM Solution

“…Equation (8) shows the algorithm for determining the corrections. Accordingly, it will be possible to determine the distribution and the spread of the corrections relative to the resultant value of the UAV position along each axis BLh.…”

“…the ionospheric delay is determined from the SBAS model [8]; -the tropospheric delay is determined from the RTCA-MOPS model (Radio Technical Commission for Aeronautics-Minimum Operational Performance Specification) [9,10].…”

Comparison of Ionospheric Correction Models Applied in Single Frequency GNSS Receivers

“…Bir yıl 37 alt zaman dilimine ayrılmış olup, bu katsayılar her bir alt zaman dilimine önceden GPS Ana Kontrol İstasyonu tarafından yüklenmekte ve bu değerler 6 günde bir güncellenmektedir (IS-GPS-200K 2019). Bu katsayıların kullanılması ile özellikle orta enlemlerde iyonosferik etkinin yaklaşık %50'si giderebilmektedir (, Klobuchar ve Doherty 1990, Komjathy 1997, Ciećko ve Grunwald 2020.…”