Open Access
The GPS Segment of the AFRL-SCINDA Global Network and the Challenges of Real-Time TEC Estimation in the Equatorial Ionosphere
Charles S. Carrano,Keith M. Groves +1 more
- pp 1036-1047
TLDR
In this paper, a methodology for real-time calibrated TEC estimation in the presence of scintillation and a highly structured ionosphere is described, where the inter-frequency biases of the GPS satellites are assumed known; they use estimates provided by the Center for Orbit Determination in Europe (CODE).Abstract:
The estimation of Total Electron Content (TEC) in the equatorial ionosphere using GPS presents a number of challenges due to the presence of strong spatio-temporal density gradients and scintillation of the satellite signals caused by F-region irregularities. In this paper we describe a methodology for real-time calibrated TEC estimation in the presence of scintillation and a highly structured ionosphere. The inter-frequency biases of the GPS satellites are assumed known; we use estimates provided by the Center for Orbit Determination in Europe (CODE). The inter-frequency bias associated with a particular receiver is estimated late at night when the ionosphere is minimally structured, using an iterative approach that minimizes the variance of verticalized TEC measured along the different satellite links. The nightly estimated receiver bias is shown to be insensitive to the assumed centroid height used in the single-layer approximation of the ionosphere. It is also relatively stable on a night to night basis, deviating from its running average most when nighttime gradients in density are largest (commonly associated with geomagnetic activity and/or equatorial spread F). A 14 day running average of the bias is used to minimize the effect of this variability on the calibrated TEC. The effectiveness of the technique is illustrated by comparing the calibrated TEC estimated using two GPS receivers connected to the same antenna. During quiescent ionospheric conditions the difference in TEC estimated with the two receivers is generally less than a couple of TECU, despite their substantially different internal biases. During scintillating conditions, the TEC from the two receivers exhibit substantial differences due to receiver errors in the measurement of pseudorange and phase, unless strict quality control techniques are applied to exclude this data from the analysis. Methods for the automated detection of receiver error due to scintillation are presented and are shown to yield reliable TEC estimates.read more
Citations
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Statistical framework for estimating GNSS bias
TL;DR: A statistical framework for estimating global navigation satellite system (GNSS) non-ionospheric differential time delay bias is presented and a new method is found to produce estimates of receiver bias that have reduced day-to-day variability and more consistent coincident vertical TEC values.
Journal ArticleDOI
Accuracy of GPS total electron content: GPS receiver bias temperature dependence
TL;DR: In this article, the authors investigated the temperature dependence of the GPS receiver bias and showed that the bias can be separated into those introduced by the satellite and those by the receiver, and that this temperature dependence varies from receiver to receiver.
Journal ArticleDOI
Statistical framework for estimating GNSS bias
TL;DR: In this article, a statistical framework for estimating global navigation satellite system (GNSS) non-ionospheric differential time delay bias is presented, which is based on the differences of measured line-integrated electron densities (total electron content: TEC) that are scaled to equivalent vertical integrated densities.
Journal ArticleDOI
Equatorial plasma bubbles and L-band scintillations in Africa during solar minimum
V. V. Paznukhov,Charles S. Carrano,Patricia H. Doherty,Keith M. Groves,Keith M. Groves,Ronald G. Caton,Cesar E. Valladares,G. K. Seemala,C. Bridgwood,J.O. Adeniyi,L. L. N. Amaeshi,Baylie Damtie,F. D'Ujanga Mutonyi,Jared O. H. Ndeda,Paul Baki,O. K. Obrou,Bonaventure Okere,G. M. Tsidu +17 more
TL;DR: In this paper, the authors reported on the longitudinal, local time and seasonal occurrence of equatorial plasma bubbles (EPBs) and L band (GPS) scintillations over equatorial Africa.
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Impacts of the December 2006 solar radio bursts on the performance of GPS
TL;DR: In this article, the authors investigated the impacts of four X class solar radio bursts (SRBs) on the performance of GPS and quantified the Sudden Increases in Total Electron Content (SITEC) caused by the solar flares.
References
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TL;DR: In this paper, a technique for retrieving the global distribution of vertical total electron content (TEC) from GPS-based measurements is described, based on interpolating TEC within triangular tiles that tessellate the ionosphere modeled as a thin spherical shell.
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Ionospheric effects of major magnetic storms during the International Space Weather Period of September and October 1999: GPS observations, VHF/UHF scintillations, and in situ density structures at middle and equatorial latitudes
Sunanda Basu,Santimay Basu,Cesar E. Valladares,H.-C. Yeh,S.-Y. Su,E. MacKenzie,P. J. Sultan,Jules Aarons,Frederick J. Rich,Patricia H. Doherty,Keith M. Groves,Terence Bullett +11 more
TL;DR: In this article, the ionospheric effects of a halo coronal mass ejection (CME) initiated on the Sun on September 20, 1999, and causing the largest magnetic storm during this month on September 22, 23, and 24, 1999 were studied through their effects on a prototype of a Global Positioning System (GPS)-based navigation system called Wide Area Augmentation System (WAAS) and their impact on global VHF/UHF communication systems.