Galileo Ionospheric Correction Algorithm: An Optimization Study of NeQuick‐G

A. Aragon‐Angel; M. Zürn; A. Rovira‐Garcia

doi:10.1029/2019rs006875

Positioning performance of the NTCM model driven by GPS Klobuchar model parameters

Journal of Space Weather and Space Climate ◽

10.1051/swsc/2018009 ◽

2018 ◽

Vol 8 ◽

pp. A20 ◽

Cited By ~ 3

Author(s):

Mohammed Mainul Hoque ◽

Norbert Jakowski ◽

Jens Berdermann

Keyword(s):

Single Frequency ◽

Activity Period ◽

Model Parameters ◽

Signal Delay ◽

Correction Algorithm ◽

Ionospheric Correction ◽

Model Driven ◽

Position Errors ◽

Klobuchar Model ◽

Range Error

Users of the Global Positioning System (GPS) utilize the Ionospheric Correction Algorithm (ICA) also known as Klobuchar model for correcting ionospheric signal delay or range error. Recently, we developed an ionosphere correction algorithm called NTCM-Klobpar model for single frequency GNSS applications. The model is driven by a parameter computed from GPS Klobuchar model and consecutively can be used instead of the GPS Klobuchar model for ionospheric corrections. In the presented work we compare the positioning solutions obtained using NTCM-Klobpar with those using the Klobuchar model. Our investigation using worldwide ground GPS data from a quiet and a perturbed ionospheric and geomagnetic activity period of 17 days each shows that the 24-hour prediction performance of the NTCM-Klobpar is better than the GPS Klobuchar model in global average. The root mean squared deviation of the 3D position errors are found to be about 0.24 and 0.45 m less for the NTCM-Klobpar compared to the GPS Klobuchar model during quiet and perturbed condition, respectively. The presented algorithm has the potential to continuously improve the accuracy of GPS single frequency mass market devices with only little software modification.

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Galileo Ionospheric Correction Algorithm Integration into the Open-Source GNSS Laboratory Tool Suite (gLAB)

Remote Sensing ◽

10.3390/rs13020191 ◽

2021 ◽

Vol 13 (2) ◽

pp. 191

Author(s):

Angela Aragon-Angel ◽

Adria Rovira-Garcia ◽

Enrique Arcediano-Garrido ◽

Deimos Ibáñez-Segura

Keyword(s):

European Space Agency ◽

Low Earth Orbit ◽

Single Frequency ◽

Research Centre ◽

Electron Content ◽

Correction Algorithm ◽

Joint Research ◽

Ionospheric Correction ◽

Total Electron ◽

Position Errors

Users of the global navigation satellite system (GNSS) operating with a single-frequency receiver must use an ionospheric correction algorithm (ICA) to account for the delay introduced on radio waves by the upper atmosphere. Galileo, the European GNSS, uses an ICA named NeQuick-G. In an effort to foster the adoption of NeQuick-G by final users, two implementations in C language have been recently made available to the public by the European Space Agency (ESA) and the Joint Research Centre (JRC) of the European Commission (EC), respectively. The aim of the present contribution is to compare the slant total electron content (STEC) predictions of the two aforementioned implementations of NeQuick-G. For this purpose, we have used actual multi-constellation and multi-frequency data for several hundreds of stations distributed worldwide belonging to the Multi GNSS Experiment (MGEX) network of the International GNSS Service (IGS). For each first day of the month during year 2019, the STECs of the two NeQuick-G versions were compared in terms of accuracy, consistency, availability, and execution time. Our study concludes that both implementations of NeQuick-G perform equivalently. Indeed, in over 99.998% of the 2125 million STECs computed, the output is exactly coincident. In contrast, 0.002% of the whole set of STECs for those rays are tangent to the Earth, the behavior of both implementations differs. We confirmed the discrepancy by processing radio-occultation actual measurements from a COSMIC-2 low Earth orbit satellite. We selected the JRC version of the Galileo ICA to be integrated into the GNSS LABoratory (gLAB) tool suite, because its open license and its processing speed (it is 13.88% faster than the ESA version). NeQuick-G outperforms the GPS ICA in STEC residuals up to 12.15 TECUs (percentile 96.23th) and in the 3D position errors, up to 5.76 m (percentile 99.18th) for code-pseudorange positioning.

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