Autonomous Single-frequency Ionospheric Correction Model for Safety-of-life Applications

2017 ◽  
Author(s):  
Denis Bouvet
Keyword(s):  
Single Frequency ◽  
Ionospheric Correction ◽  
Correction Model

scholarly journals Assessment and Comparison of Broadcast Ionospheric Models: NTCM-BC, BDGIM, and Klobuchar

2020 ◽  
Vol 12 (7) ◽  
pp. 1215 ◽  
Author(s):  
Chao Yang ◽  
Jing Guo ◽  
Tao Geng ◽  
Qile Zhao ◽  
Kecai Jiang ◽  
...  
Keyword(s):  
Ionospheric Delay ◽  
Global Navigation Satellite Systems ◽  
Single Frequency ◽  
Electron Content ◽  
Ionospheric Correction ◽  
Total Electron ◽  
Correction Model ◽  
Satellite Systems ◽  
Satellite Navigation System ◽  
Navigation Data

For single-frequency Global Navigation Satellite Systems (GNSSs) users, ionospheric delay is the main error source affecting the accuracy of positioning. Applying a broadcast ionospheric correction model to mitigate the ionospheric delay is essential for meter-to-decimeter-level accuracy positioning. To provide support for real-time single-frequency operations, particularly in the China area, we assessed the performance of three broadcast ionospheric correction models, namely, the Neustrelitz total electron content (TEC) broadcast model (NTCM-BC), the BeiDou global broadcast ionospheric delay correction model (BDGIM), and the Klobuchar model. In this study, the broadcast coefficients of Klobuchar and BDGIM are obtained from the navigation data files directly. Two sets of coefficients of NTCM-BC for China and global areas are estimated. The slant total electron contents (STEC) data from more than 80 validation stations and the final vertical TEC (VTEC) data of the Center for Orbit Determination in Europe (CODE) are used as independent benchmarks for comparison. Compared to GPS STEC during the period of Day of Year (DOY) 101~199, 2019, the ionospheric correction ratio of NTCM-BC, BDGIM, and Klobuchar are 79.4%, 64.9%, and 57.7% in China, respectively. For the global area, the root-mean-square (RMS) errors of these three models are 3.67 TECU (1 TECU = 1016 electrons/m2), 5.48 TECU, and 8.92 TECU, respectively. Compared to CODE VTEC in the same period, NTCM-BC, BDGIM, and Klobuchar can correct 72.6%, 69.8%, and 61.7% of ionospheric delay, respectively. Hence, NTCM-BC is recommended for use as the broadcast ionospheric model for the new-generation BeiDou satellite navigation system (BDS) and its satellite-based augmentation system.

scholarly journals Impact of Approximate Implementation manner in Klobuchar Model

2021 ◽  
Vol 64 (4) ◽  
pp. RS440
Author(s):  
Aghyas Aljuneidi ◽  
Hala Tawfek Hasan
Keyword(s):  
Single Frequency ◽  
Gps Receiver ◽  
Reference Field ◽  
International Geomagnetic Reference Field ◽  
Ionospheric Correction ◽  
Correction Model ◽  
Klobuchar Model ◽  
Magnetic Model ◽  
Implementation In Matlab ◽  
Made In

This paper focuses on the approximations that John A. Klobuchar made in mid 70s in his famous algorithm of ionospheric correction model for single frequency GPS receiver. At that time Klobuchar used a system of fixed geomagnetic north pole coordinates which are not accurate nowadays according to the International Geomagnetic Reference Field and to the World Magnetic Model because the geomagnetic poles move slowly. In addition, Klobuchar had to do other trigonometry simplifications in his implementation to avoid sophisticated computations. In order to evaluate this approximate implementation in a single frequency GPS receiver, ionospheric time and range delay are estimated on the entire day of January 1st 2010, using a different implementation in MATLAB. The required GPS data is obtained from recorded RINEX files at UDMC near DAMASCUS, SYRIA. In this comparative study, we reformulated the standard equations of Klobuchar model and examined the influence of its approximations on the ionospheric range delay and found a non- negligible bias in order of ten centimeters, whereas the influence of the movement of the geomagnetic poles was in order of few centimeters.

scholarly journals STORM: An empirical storm-time ionospheric correction model 2. Validation

Radio Science ◽  
2002 ◽  
Vol 37 (5) ◽  
pp. 4-1-4-14 ◽  
Author(s):  
E. A. Araujo-Pradere ◽  
T. J. Fuller-Rowell
Keyword(s):  
Ionospheric Correction ◽  
Correction Model

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

2018 ◽  
Vol 8 ◽  
pp. A20 ◽  
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.

GIM-ingested NeQuick model applied for GPS single frequency ionospheric correction in China

ISAPE2012 ◽  
2012 ◽  
Author(s):  
Ming Ou ◽  
Hong-Bo Zhang ◽  
Dun Liu ◽  
Xiao Yu ◽  
Wei-Min Zhen
Keyword(s):  
Single Frequency ◽  
Ionospheric Correction

scholarly journals Galileo single frequency ionospheric correction: performances in terms of position

GPS Solutions ◽  
2012 ◽  
Vol 17 (1) ◽  
pp. 63-73 ◽  
Author(s):  
Benoît Bidaine ◽  
Matthieu Lonchay ◽  
René Warnant
Keyword(s):  
Single Frequency ◽  
Ionospheric Correction

scholarly journals An Improved BDS Satellite-Induced Code Bias Correction Model Considering the Consistency of Multipath Combinations

2018 ◽  
Vol 10 (8) ◽  
pp. 1189 ◽  
Author(s):  
Lin Pan ◽  
Fei Guo ◽  
Fujian Ma
Keyword(s):  
Piecewise Linear ◽  
Satellite System ◽  
Single Frequency ◽  
Model Parameters ◽  
Correction Model ◽  
Cycle Slips ◽  
Linear Correction ◽  
Code Bias ◽  
Navigation Signals ◽  
Orbit Types

The satellite-induced systematic biases were identified to exist in the code observations from BeiDou navigation satellite system (BDS) satellites using multipath (MP) combinations. The current correction model for satellite-induced code bias (SICB) does not take into account the consistency of MP combinations, which limits the accuracy of the developed model. Both the cycle slips and different tracking of a satellite at different stations can affect the absolute values of MP combinations, although the variations remain unchanged. An improved SICB piecewise linear correction model as a function of elevations is proposed. We estimate the model parameters for each frequency and for each satellite. The single-difference of MP combinations in the domain of elevation angles is carried out to remove the unknown ambiguities and stable hardware delays so that the SICB modeling is free of the effects of MP combination inconsistency. In addition, a denser elevation node separation of 1°, rather than the 10° usually employed by the traditional model, is used to describe the more precise SICB variations. The SICB corrections show significant differences among orbit types and frequency bands. The SICB variations have much less effect on Inclined Geosynchronous Orbit (IGSO) satellites than on Medium Earth Orbit (MEO) satellites for the regional BDS (BDS-2). The B1 signal has the largest SICB corrections, which can be up to 0.9 m close to zenith for BDS-2 MEO satellites, and the B2 signal follows. After adding the SICB corrections to the code observations, the elevation-dependent code biases vanish, and we can obtain improved code observations. After applying the improved SICB correction model, the root mean square (RMS) values of MP combination time series are reduced by 7%, 6% and 2%, and 18%, 14% and 5% on the B1, B2 and B3 frequencies for the BDS-2 IGSO and MEO satellites, respectively. For comparison, we also establish the traditional SICB correction model. With the traditional SICB correction model, the corresponding RMS MP combinations are smaller than those of uncorrected MP series, but slightly larger than those of corrected MP series using the improved SICB correction model. To validate the effectiveness and correctness of our proposed model, single-frequency precise point positioning (PPP) processing with BDS-2 MEO and IGSO satellites is conducted. An accuracy improvement of 24%, 19% and 89%, and 7%, 7% and 6% for the single-frequency PPP applying the improved SICB corrections over the case without SICB corrections and the case using the traditional SICB corrections in east, north and vertical directions is achieved, respectively. Although only centimeter-level SICB variations could be observed for the two legacy signals B1 and B3 and the three new navigation signals B1C, B2a and B2b transmitted by the satellites of global BDS demonstration system (BDS-3S), we still establish an effective SICB correction model on the B1 and B3 frequencies for BDS-3S IGSO satellites, and the RMS MP combinations are reduced by 1–4% after applying the improved SICB corrections.

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

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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