Estimation of higher‐order ionospheric errors in GNSS positioning using a realistic 3‐D electron density model

Abstract

[1] The accuracy of the positioning systems such as GPS, GLONASS or Galileo is heavily affected by the presence of the ionosphere. Ionosphere-free dual-frequency algorithms used for positioning applications remove most of the ionospheric error but do not take into account its higher-order terms. In addition, the raypaths and total electron content (TEC) are assumed to be the same for both frequencies. This leads to centimeter-level range errors that can cause millimeter-level errors in positioning. In this paper an accurate estimation of the higher-order ionospheric errors based on a realistic 3-D electron density model is presented. A numerical homing-in ray-tracing algorithm is implemented to rigorously calculate satellite to receiver ray trajectories. The numerical simulations performed showed that higher-order ionospheric residual range errors may reach several centimeters (up to 5 cm) at low and middle latitudes; however, at high latitudes they hardly exceed several millimeters (up to 1 cm).Citation: Kashcheyev, A., B. Nava, and S. M. Radicella (2012), Estimation of higher-order ionospheric errors in GNSS positioning using a realistic 3-D electron density model, Radio Sci., 47, RS4008,

The IONORT-ISP-WC system: Inclusion of an electron collision frequency model for the D-layer

“…Ray-tracing can generally be performed accurately if the 3-D electron density distribution between the transmitter and the receiver is known (Kashcheyev et al, 2012). A comprehensive specification of the ionosphere in terms of electron density, neutral particles-electrons collision frequency, and geomagnetic field is required in order to carry out an accurate ray-tracing.…”

Tomography of the ionospheric electron density with geostatistical inversion

“…The NeQuick model is currently being developed at the International Centre for Theoretical Physics (ICTP) in Trieste, Italy, and at the University of Graz, Austria (see Hochegger et al, 2000;Radicella and Leitinger, 2001;Nava et al, 2008). It is widely used in ionospheric delay and TEC estimation for trans-ionospheric ray paths (see, e.g., Kashcheyev et al, 2012). The vertical electron density profiles of the NeQuick model are modeled by summing up five semi-Epstein layers whose shape parameters, such as peak ionization, peak height and semi-thickness, are deduced from the ITU-R (ITU Radio-Communication Sector) foF2 and M(3000)F2 models (see ITU-R, 1995).…”

On the determination of the effect of horizontal ionospheric gradients on ranging errors in GNSS positioning

“…Before this, we note that for frequencies of 1 GHz and higher, the traditional technique has been validated against the results of the direct ray tracing by many authors, including ourselves (e.g., Strangeways and Ioannides 2002;Gherm et al 2006;Hoque and Jakowski 2008;Kashcheyev et al 2012). This gives validity to its use in validating the results of calculations employing the alternative technique developed here.…”

“…Many authors have employed a purely numerical treatment of the contribution of the ionosphere into GNSS range error, (Ashmanets et al 1996;Strangeways andIoannides 1999, 2002;Strangeways 2000;Strangeways and Nagarajoo 2005;Kashcheyev et al 2012) in which the appropriate codes for direct numerical solution using the geometrical optics (GO) equations were developed, when assessing the errors of range measurements analytically. The perturbation theory has also been used in numerous papers (Hartmann and Leitinger 1984;Brunner and Gu 1991;Hajj 1992, 1993;Prokopov and Zanimonska 2005;Gherm et al 2006;Kim and Tinin 2007;Hernandez-Pajares et al 2007;Jakowski 2008, 2011;Moore and Morton 2011;Petrie et al 2011) when employing the GO equations.…”