Comparative Study of Methods for Calculating Ionospheric Points and Describing the GNSS Signal Path

Prol, Fabricio dos Santos; Camargo, Paulo de Oliveira; Muella, M. T. A. H.

doi:10.1590/s1982-21702017000400044

Cited by 10 publications

(8 citation statements)

References 16 publications

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“…Generating dTEC maps requires the corresponding longitude and latitude of ionospheric piercing point (IPP) position, which are estimated in [40][41][42]; where λ r and φ r are longitude and latitude of the receiver respectively.…”

Section: Methods Of Generating the Two-dimensional Dtec Mapsmentioning

confidence: 99%

Long-Term Study on Medium-Scale Traveling Ionospheric Disturbances Observed over the South American Equatorial Region

et al. 2021

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Using data collected by the GNSS dual-frequency receivers network, de-trended TEC maps were generated to identify and characterize the medium-scale traveling ionospheric disturbances (MSTIDs) over the South American equatorial region (latitude: 0∘ to 15∘ S and longitude: 30∘ to 55∘ W) during solar cycle 24 (from January 2014 to December 2019). A total of 712 MSTIDs were observed during quiet geomagnetic conditions. The Frequency of occurrence of MSTID is high during the solar maximum and low in the minimum phase. This might be due to the solar cycle dependence of gravity wave activity in the lower atmosphere and gravity wave propagation conditions in the thermosphere. The predominant daytime MSTIDs, representing 80% of the total observations, occurred in winter (June-August season in the southern hemisphere) with the secondary peak in the equinox; while the evening time MSTIDs, representing 18% of the entire events, occurred in summer (December to February season) and equinox (March to May and September to November), and the remaining 2% of the MSTIDs were observed during nighttime. The seasonal variation of the MSTID events was attributed to the source mechanisms generating them, the wind filtering and dissipation effects, and the local time dependency. The horizontal wavelengths of the MSTIDs were mostly concentrated between 500 and 800 km, with the mean value of 667 ± 131 km. The observed periods ranged from 30 to 45 min with the mean value of 36 ± 7 min. The observed horizontal phase speeds were distributed around 200 to 400 m/s, with the corresponding mean of 301 ± 75 m/s. The MSTIDs in the winter solstice and equinoctial months preferentially propagated northeastward and northwestward. Meanwhile, during the summer solstice, they propagated in all directions. The anisotropy of the propagation direction might be due to several reasons: the wind and dissipative filtering effects, ion drag effects, the primary source region, and the presence of the secondary or tertiary gravity waves in the thermosphere. Atmospheric gravity waves from strong convective sources might be the primary precursor for the observed equatorial MSTIDs. In all seasons, we noted that the MSTIDs propagating southeastward were probably excited by the likely gravity waves generated by the intertropical convergence zone (ITCZ).

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Section: Methods Of Generating the Two-dimensional Dtec Mapsmentioning

confidence: 99%

Long-Term Study on Medium-Scale Traveling Ionospheric Disturbances Observed over the South American Equatorial Region

et al. 2021

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“…The VTEC at the IPP (within the geographical extent of the grid points) is computed as a linear function of the values at grid points. The VN-DGNSS server uses distance weighted spatial interpolation [52], [53]:…”

Section: Ssr Vtec-shmentioning

confidence: 99%

Using PPP Information to Implement a Global Real-Time Virtual Network DGNSS Approach

Wang

Neupane

Farrell

2022

IEEE Trans. Veh. Technol.

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Differential GNSS (DGNSS) has been demonstrated to provide reliable, high-quality range correction information enabling real-time navigation with centimeter to sub-meter accuracy, which is required for applications such as connected and autonomous vehicles. However, DGNSS requires a local reference station near each user. For a continental or global scale implementation, this information dissemination approach would require a dense network of reference stations whose construction and maintenance would be prohibitively expensive. Precise Point Positioning (PPP) affords more flexibility as a public service for Global Navigation Satellite Systems (GNSS) receivers, but its State Space Representation (SSR) format is not supported by most receivers in the field or on the market.This article proposes a novel Virtual Network DGNSS (VN-DGNSS) approach and an optimization algorithm that is key to its implementation. The approach capitalizes on the existing PPP infrastructure without the need for new physical reference stations. Specifically, no reference station is needed in the local vicinity of any user. By connecting to public GNSS SSR data services, a VN-DGNSS server maintains current information about satellite code bias, satellite orbit and clock, and atmospheric models. Construction of the Radio Technical Commission for Maritime Services (RTCM) Observation Space Representation (OSR) messages from this SSR information requires both the signal time-of-transmission and the satellite position at that time which are consistent with the time-of-reception for each client. This article presents an algorithm to determine these quantities. Then the VN-DGNSS computes and transmits RTCM OSR messages to user receivers. This approach achieves global dissemination coverage for real-time navigation without the need for additional local base stations near each user.The results of real-time stationary and moving platform evaluations are included, using u-blox M8P and ZED-F9P receivers. The performance surpasses the Society of Automotive Engineering (SAE) specification (68% of horizontal error ⩽ 1.5 m and vertical error ⩽ 3 m) and shows significantly better horizontal performance than GNSS Open Service (OS). The moving tests also show better horizontal performance than the ZED-F9P receiver with Satellite Based Augmentation Systems (SBAS) enabled and achieve the lane-level accuracy (95% of horizontal errors less than 1 meter).

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“…In general, h m is identified by the single-layer model where all free electrons are concentrated in the infinitesimal spherical shell at the assumed altitude (450 km). Other formulations of mapping functions are possible too, for instance, from the Klobuchar algorithm (mF), presented in Rui et al (2011):…”

Section: Spp With Ionospheric Corrections Using the Klobuchar Algoritmentioning

confidence: 99%

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

Fischer

Cellmer

Nowel

2021

Geosci. Instrum. Method. Data Syst.

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Abstract. This paper proposes a new mathematical method of ionospheric delay estimation in single point positioning (SPP) using a single-frequency receiver. The proposed approach focuses on the Δ vertical total electron content (VTEC) component estimation (MSPPwithdVTEC) with the assumption of an initial and constant value equal to 5 TECU in any observed epoch. The principal purpose of the study is to examine the reliability of this approach to become independent from the external data in the ionospheric correction calculation process. To verify the MSPPwithdVTEC, the SPP with the Klobuchar algorithm was employed as a reference model, utilizing the coefficients from the navigation message. Moreover, to specify the level of precision of the MSPPwithdVTEC, the SPP with the International Global Navigation Satellite Systems (GNSS) Service (IGS) TEC map was adopted for comparison as the high-quality product in the ionospheric delay determination. To perform the computational tests, real code data were involved from three different localizations in Scandinavia using two parallel days. The criterion was the ionospheric changes depending on geodetic latitude. Referring to the Klobuchar model, the MSPPwithdVTEC obtained a significant improvement of 15 %–25 % in the final SPP solutions. For the SPP approach employing the IGS TEC map and for the MSPPwithdVTEC, the difference in error reduction was not significant, and it did not exceed 1.0 % for the IGS TEC map. Therefore, the MSPPwithdVTEC can be assessed as an accurate SPP method based on error reduction value, close to the SPP approach with the IGS TEC map. The main advantage of the proposed approach is that it does not need external data.

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Comparative Study of Methods for Calculating Ionospheric Points and Describing the GNSS Signal Path

Cited by 10 publications

References 16 publications

Long-Term Study on Medium-Scale Traveling Ionospheric Disturbances Observed over the South American Equatorial Region

Long-Term Study on Medium-Scale Traveling Ionospheric Disturbances Observed over the South American Equatorial Region

Using PPP Information to Implement a Global Real-Time Virtual Network DGNSS Approach

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

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