Performance of Ion-Free and GRAPHIC Combinations in Multi-GNSS PPP under Different Ionospheric Conditions in Brazil
Article Sidebar
Main Article Content
Abstract
This paper preliminarily evaluates the performance of multi-GNSS Precise Point Positioning (PPP) using the GRAPHIC method and dual- (IF2) and triple-frequency (IF3) ion-free combinations under contrasting ionospheric conditions in Brazil. RINEX3 data from five stations of the Brazilian Network for Continuous Monitoring of GNSS Systems (RBMC) were processed for March and June 2024, totaling 60 days of observations, with daily three-hour sessions starting at 00:00 UTC. The assessment considered satellite availability, solution geometry through position dilution of precision (PDOP), convergence time, positioning discrepancies in the Local Geodetic System, and pseudorange and carrier-phase residuals as a function of elevation angle. The results show that IF2 achieved the best overall performance, preserving greater multi-constellation availability, with approximately 28 satellites per epoch and PDOP close to 1, while also providing faster convergence and smaller final discrepancies, especially in June. GRAPHIC showed greater dispersion, associated with the propagation of pseudorange noise into the quasi-carrier observable. IF3, in turn, was penalized by the lower effective availability of simultaneous triple-frequency observations, decreasing to approximately 12 satellites per epoch and increasing PDOP, which resulted in longer convergence times and larger residual errors, especially in the vertical component. The results indicate that the direct application of triple-frequency combinations, under the tracking conditions of the analyzed stations, did not provide systematic improvement over IF2. Therefore, its operational adoption requires adequate multifrequency availability, quality control, and explicit modeling of inter-frequency biases.
Downloads
Article Details
Section
This work is licensed under a Creative Commons Attribution 4.0 International License.
Authors who publish in this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgment of the work's authorship and initial publication in this journal.
- Authors can enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgment of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) before and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (see "The Effect of Open Access").
How to Cite
References
Aguiar, C. R., Monico, J. F. G., & Moraes, A. O. (2025). Impact of ionospheric scintillations on GNSS
availability and precise positioning. Space Weather, 23, e2024SW004217. DOI: 10.1029/2024SW004217.
Ashby, N. (2003). Relativity in the Global Positioning System. Living Reviews in Relativity, 6, 1. DOI:10.12942/lrr-2003-1
Ashby, N. (2004). The Sagnac effect in the Global Positioning System. In G. Rizzi & M. L. Ruggiero (Eds.),
Relativity in rotating frames: Relativistic physics in rotating reference frames (pp. 11–28). Kluwer
Academic Publishers.
Basu, S., Groves, K. M., Basu, S., & Sultan, P. J. (2002). Specification and forecasting of scintillations in
communication/navigation links: current status and future plans. Journal of Atmospheric and Solar-
Terrestrial Physics, 64(16), 1745–1754. DOI: 10.1016/S1364-6826(02)00124-4
Blewitt, G. (1990). An automated editing algorithm for GPS data. Geophysical Research Letters, 17(3), 199–
202.
Choy, S. (2009). An investigation into the accuracy of single frequency precise point positioning (PPP)
[Doctoral dissertation, RMIT University].
Dal Poz, W. R., Silva, A. C., Santos, A. P. dos, Medeiros, N. das G., Ferreira, Í. O., & Oliveira, J. C. de. (2025).
Impacts of the Great May 2024 geomagnetic storm on precise point positioning. Revista Brasileira de
Geografia Física, 18(3), 1697–1713. DOI: 10.26848/rbgf.v18.3.p1697-1713
Deo, M., & El-Mowafy, A. (2017). Triple-frequency GNSS models for PPP with float ambiguity estimation:
performance comparison using GPS. Survey Review, 50(360), 249–261. DOI:
10.1080/00396265.2016.1263179
Elsheikh, M., Iqbal, U., Noureldin, A., & Korenberg, M. (2023). The implementation of precise point
positioning (PPP): a comprehensive review. Sensors, 23, 8874. DOI: 10.3390/s23218874
Ge, Y., Dai, P., Qin, W., Yang, X., Zhou, F., Wang, S., & Zhao, X. (2019). Performance of multi-GNSS precise
point positioning time and frequency transfer with clock modeling. Remote Sensing, 11, 347. DOI:
10.3390/rs11030347
Glaner, M. F., & Weber, R. (2023). An open-source software package for precise point positioning: raPPPid.
GPS Solutions, 27, 174. DOI: 10.1007/s10291-023-01488-4
Hauschild, A. (2017). Combinations of observations. In: P. J. G. Teunissen & O. Montenbruck (Eds.), Springer
handbook of global navigation satellite systems. Springer.
Hobiger, T. & Jakowski, N. (2017). Atmospheric Signal Propagation. In: P. J. G. Teunissen & O. Montenbruck
(Eds.), Springer handbook of global navigation satellite systems. Springer.
Jiang, X., Li, H., Guo, L., Ye, D., Yang, K., & Li, J. (2024). Research on the Ionospheric Delay of Long-Range
Short-Wave Propagation Based on a Regression Analysis. Remote Sensing, 16(3), 553. DOI:
10.3390/rs16030553
Klobuchar, J. A. (1987). Ionospheric time-delay algorithm for single-frequency GPS users. IEEE Transactions
on Aerospace and Electronic Systems, AES-23(3), 325–331.
Kouba, J., Lahaye, F., & Tétreault, P. (2017). Precise Point Positioning. In: Teunissen, P. J. G.; Montenbruck,
O. (eds) Springer Handbook of Global Navigation Satellite Systems. Springer, Berlin.
Landskron, D., & Böhm, J. (2018). VMF3/GPT3: Refined discrete and empirical troposphere mapping
functions. Journal of Geodesy, 92(4), 349–360. DOI: 10.1007/s00190-017-1066-2
Li, M., & Yuan, Y. (2021). Estimation and analysis of the observable-specific code biases estimated using
multi-GNSS observations and global ionospheric maps. Remote Sensing, 13(16), 3096. DOI:
10.3390/rs13163096
Marques, H. A., Monico, J. F. G., Marques, H. A. S., Susi, M., Borio, D., Park, J., & Wȩzka, K. (2025).
Evaluating GPS and Galileo Precise Point Positioning (PPP) Under Various Ionospheric Conditions
During Solar Cycle 25. Remote Sensing, 17(18), 3169. DOI: 10.3390/rs17183169
Matsuoka, M. T., Collischonn, C., Klein, I., Camargo, P. O., & Pereira, V. A. S. (2013). Impacto de tempestade
geomagnética na ionosfera e no posicionamento com GNSS: estudo de caso para 20 de novembro de 2003
na região brasileira. Boletim de Ciências Geodésicas.
Monico, J. F. G. (2008). Posicionamento pelo GNSS: descrição, fundamentos e aplicações. (2. ed.). Editora UNESP.
Monico, J. F. G., de Paula, E. R., Moraes, A. O. et al. (2022). The GNSS NavAer INCT project overview and
main results. J. Aerosp. Technol. Manag., vol. 14. DOI: 10.1590/jatm.v14.1249
Montenbruck, O., Schmid, R., Mercier, F., Steigenberger, P., Noll, C., Fatkulin, R., Kogure, S., & Ganeshan,
A. (2015). GNSS satellite geometry and attitude models. Advances in Space Research, 56(6), 1015–1029.
DOI: 10.1016/j.asr.2015.06.019
Montenbruck, O., Steigenberger, P., Prange, L., Deng, Z., Zhao, Q., Perosanz, F., Romero, I., Noll, C., Stürze,
A., Weber, G., Schmid, R., MacLeod, K., & Schaer, S. (2017). The Multi-GNSS Experiment (MGEX) of
the International GNSS Service (IGS): Achievements, prospects and challenges. Advances in Space
Research, 59(7), 1671–1697. DOI: 10.1016/j.asr.2017.01.011
Moraes, A. O., de Paula, E. R., Muella, M. T. A. H., & Perrella, W. J. (2014). On the second order statistics
for GPS ionospheric scintillation modeling. Radio Science, 49(2), 94–105. DOI: 10.1002/2013RS005270
Schönemann, E. (2014). Analysis of GNSS raw observations in PPP solutions. [Tese de Doutorado, Technische
Universität Darmstadt].
Shi, C., Gu, S., Lou, Y., & Ge, M. (2012). An improved approach to model ionospheric delays for singlefrequency
precise point positioning. Advances in Space Research, v. 49, n. 12, p. 1698–1708. DOI:
10.1016/j.asr.2012.03.016
Sousasantos, J., Rodrigues, F.S., Moraes, A.O. et al. (2024). On the estimation of scintillation severity using
background F-region peak densities: description and example results using GOLD observations. GPS Solut
28, 62. DOI: 10.1007/s10291-023-01602-6
Su, K., & Jin, S. (2019). Triple frequency carrier phase precise time and frequency transfer models for BDS 3.
GPS Solutions, 23, 86. DOI: 10.1007/s10291-019-0879-2
Su, K., Jin, S., & Jiao, G. (2020). Assessment of multi-frequency global navigation satellite system precise
point positioning models using GPS, BeiDou, GLONASS, Galileo and QZSS. Measurement Science and
Technology, 31. DOI: 10.1088/1361-6501/ab69d5
Tegedor, J., & Øvstedal, O. (2014). Triple carrier precise point positioning (PPP) using GPS L5. Survey
Review, 46(337). DOI: 10.1179/1752270613Y.0000000076
Teunissen, P. J. G., & Montenbruck, O. (Eds.). (2017). Springer handbook of global navigation satellite
systems. Springer. DOI: 10.1007/978-3-319-42928-1
Tian, Y., Gong, X., Zheng, F. et al. (2026). An instantaneous and reliable precise point positioning integer
ambiguity resolution method based on multistage residual tests. GPS Solut 30, 6. DOI: 10.1007/s10291-
025-01974-x
Veettil, S. V., Aquino, M., Marques, H. A., & Moraes, A. (2020). Mitigation of ionospheric scintillation effects
on GNSS precise point positioning (PPP) at low latitudes. Journal of Geodesy, 94, 15. DOI:
10.1007/s00190-020-01345-z
Wang, Z., Wang, R., Wang, Y., Hu, C., & Liu, B. (2022). Modelling and assessment of a new triple-frequency
IF1213 PPP with BDS/GPS. Remote Sensing, 14(18), 4509. DOI: 10.3390/rs14184509
Wu, J. T., Wu, S. C., Hajj, G. A., Bertiger, W. I., & Lichten, S. M. (1993). Effects of antenna orientation on
GPS carrier phase. Manuscripta Geodaetica, 18(2), 91–98. DOI: 10.1007/BF03655303
Wu, Z., Wang, Q., Yu, Z., Hu, C., Liu, H., & Han, S. (2022). Modeling and performance assessment of precise
point positioning with multi-frequency GNSS signals. Measurement. DOI:
10.1016/j.measurement.2022.111687
Xiang, Y., Gao, Y., & Li, Y. (2020). Reducing convergence time of precise point positioning with ionospheric
constraints and receiver differential code bias modeling. Journal of Geodesy, 94(8). DOI: 10.1007/s00190-
019-01334-x
Yang, H., Ren, X., Liu, M., & Zhang, X. (2024). Dual-frequency to five-frequency real-time precise point
positioning using new BDS-3 PPP-B2b service. Earth, Planets and Space, 76, 82. DOI: 10.1186/s40623-024-02031-6
Yang, Z., & Morton, Y. T. J. (2025). Impacts of the May 2024 extreme geomagnetic storm on global highaccuracy
GPS positioning solutions. Space Weather, 23. DOI: 10.1029/2025SW004547
Zajdel, R., Steigenberger, P., & Montenbruck, O. (2022). On the potential contribution of BeiDou-3 to the
realization of the terrestrial reference frame scale. GPS Solutions, 26, 109. DOI: 10.1007/s10291-022-
01298-0
Zaupa, J. P. V., Alves, D. B. M., & Setti Jr, P. T. (2022). Influência da ionosfera no posicionamento por ponto
GPS e multi-GNSS em diferentes períodos do dia. [Trabalho apresentado]. XII CBCG (Colóquio
Brasileiro de Ciências Geodésicas) e V SBG (Simpósio Brasileiro de Geomática), Curitiba, PR, Brasil.
Zaupa, J. P. V. (2025). Posicionamento por ponto preciso multi-GNSS: implementação e análises. [Dissertação
de Mestrado, Universidade Estadual Paulista “Júlio de Mesquita Filho”]. Repositório Institucional
UNESP. https://hdl.handle.net/11449/313230.
Zaupa, J. P. V., Alves, D. B. M., & Setti Jr, P. T. (2025). Robustez das combinações livres da ionosfera no
PPP multi-GNSS sob diferentes níveis de variabilidade ionosférica para uma estação de monitoramento
brasileira. I Congresso Internacional de Regularização Fundiária & VIII Simpósio Brasileiro de Ciências
Geodésicas e Tecnologias da Geoinformação (I CIRF & VIII SIMGEO), Recife, PE, Brazil. DOI:
10.5281/zenodo.17135729
Zaupa, J. P. V., Alves, D. B. M., & Setti Jr., P. T. (2026a). APPPOLO: A Brazilian processing software for
multi-GNSS precise point positioning. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial
Information Sciences, X-3/W4-2025, 379–385. DOI: 10.5194/isprs-annals-X-3-W4-2025-379-2026
Zaupa, J. P. V., de Souza, F. T. L., Ferreira, L. G., Yamashiro, H. Y., Gouveia, T. A. F., Alves, D. B. M.,
Monico, J. F. G., Pereira, V. A. S., & Setti Júnior, P. T. (2026b). Ionospheric and neutrosphere impacts on
multi-GNSS kinematic PPP during geomagnetic storms: A global study. Sensors, 26(13), 4037. DOI:
10.3390/s26134037
Zhang, Q., Zhao, L., & Zhao, L. (2021). A two-step robust adaptive filtering algorithm for GNSS kinematic
precise point positioning. Chinese Journal of Aeronautics, 34(10), 210–219. DOI:
10.1016/j.cja.2020.10.033