Klobuchar and Nequick G Ionospheric Models Comparison for Multi-GNSS Single-Frequency Code Point Positioning in the Brazilian Region

Abstract

One of the main error sources in GNSS positioning comes from the ionosphere, an atmospheric layer that stays in the signal path between the satellite and the receiver. For single frequency positioning, the ionospheric effects can be minimized by using an ionospheric model e.g. Klobuchar or NeQuick G. These models are respectively associated to GPS and Galileo systems through their navigation messages, which broadcast coefficients that describe the worldwide ionospheric behavior, and the calculated ionospheric delay is then applied in the pseudorange observations. In this paper, it is presented a comparison between these two models in multi-GNSS (GPS and Galileo) single frequency point positioning, considering two Brazilian stations at different magnetic latitudes, and covered months of weak and strong ionospheric activity from 2013 to 2018. The results indicate a better performance of NeQuick G model compared to the Klobuchar. Considering all the analyzed periods and stations, Klobuchar improves the positioning accuracy in 16% and 50% in periods of weak and strong ionospheric activity, respectively, while NeQuick G improves the accuracy in 31% and 55%.

Characterization and Climatological Modeling of Equatorial Ionization Anomaly (EIA) Crest Position

“…These models are used to estimate the ionospheric delay by computing the ionospheric TEC along the GPS/GNSS signal raypath between the user and transmitter. The Klobuchar model has been designed, using a half cosine function and eight coefficients of two third‐degree polynomials, to represent the diurnal, seasonal, geomagnetic latitude, longitude, and solar activity dependency of the delay (TEC) (JÚNIOR et al., 2019; Klobuchar, 1987). The nighttime delay (TEC) is represented by a constant delay that is 5 ns (9 TECu).…”

Local Mitigation of Higher-Order Ionospheric Effects in DFMC SBAS and System Performance Evaluation

“…Therefore, in this work, we propose the local DFMC SBAS corrections with the HOI delay mitigation. The HOI delays are computed from the local TEC values at stations in Thailand based on the Klobuchar model (Setti et al 2019). The local DFMC SBAS corrections are generated by using the pseudorange residual errors of local reference stations with the minimum sum-variance and IF carrier smoothing code techniques.…”

Single point positioning with vertical total electron content estimation based on single-epoch data

“…The TEC unit is equal to 10 16 electrons per square metre (in the cross-section of 1 m 2 ) (Ciraolo, 2005). To calculate and reduce such effect on the GPS code measurement, Stępniak (2016) distinguished different types of models and mathematical estimating methods: physical-theoretical (e.g. Chapman's model), physical-empirical (e.g.…”