GPS availability and positioning issues when the signal paths are aligned with ionospheric plasma bubbles

Moraes, Alison de Oliveira; Vani, Bruno César; Costa, Emanoel; Abdu, M. A.; Paula, E. R. de; Sousasantos, Jonas; Monico, João Francisco Galera; Forte, Biagio; Negreti, P. M. D. S.; Shimabukuro, Milton Hirokazu

doi:10.1007/s10291-018-0760-8

Cited by 52 publications

(25 citation statements)

References 34 publications

(39 reference statements)

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“…The Septentrio PolaRxS monitor provides a flag indicating the occurrences of cycle slips in the receiver tracking loop, followed by periods of losses of phase lock, as recently discussed in detail by Moraes et al (). In Figures 3, 4, and 6 of that reference, in association with the corresponding discussion, the authors address the aspects of detected cycle slips in terms of the parameters S 4 and α .…”

Section: Measurementsmentioning

confidence: 99%

Ionospheric Scintillation Fading Coefficients for the GPS L1, L2, and L5 Frequencies

et al. 2018

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The terrestrial ionosphere over low‐latitude regions presents the unique phenomena of the equatorial ionization anomaly (characterized by global maximum in plasma concentration) and plasma‐depleted regions known as equatorial plasma bubbles and associated smaller‐scale plasma irregularities. Transionospheric radio signals such as those from Global Navigation Satellite Systems constellations, traveling across this ambient, may suffer severe scintillation in amplitude and phase due to these plasma structures. Presently, three civilian signals available for GPS users, at L1 (1575.42 MHz), L2C (1227.60 MHz), and L5 (1176.45 MHz) are used to investigate the propagation effects due to these irregularities. The purpose of the present work is to evaluate statistically the distribution of severe fade events for each of these carrier frequencies based on the nonlinear ionospheric propagation effects as represented by the fading coefficients of α‐μ distribution. The results from the analyses of data sets recorded by stations at different geomagnetic latitude locations in Brazil show that regions closer to the equatorial ionization anomaly crest present higher probability of severe fade events. Additionally, the L5 signals, dedicated for safety‐of‐life applications, revealed more unfavorable results when compared to the L1 and L2C frequencies. The results further showed that for 0.8 ≤ S4 ≤ 1.0 the probabilities of fades deeper than −10 dB were between 8.0% and 6.5% depending on the station position. Considering the case of fades deeper than −20 dB, the results reach values near 1%, which is quite concerning. These results show empirically the fading environment that users of the new civilian signals may experience in low‐latitude region. Additionally, the fading coefficients may help in the comprehension of the distribution of amplitude scintillation and its relation with the frequency used, aiding in the future the development of signal processing algorithms capable to mitigate errors for navigation users.

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Section: Measurementsmentioning

confidence: 99%

Ionospheric Scintillation Fading Coefficients for the GPS L1, L2, and L5 Frequencies

et al. 2018

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“…The effects are more severe in the equatorial/low latitudes, where the occurrence of scintillation is associated with the ridges of the EIA, delimited by 15° to the north and south of the geomagnetic equator (Basu et al, 2002). Brazil has a large part of its territory located in the equatorial and low latitudes regions, strongly affected by this effect and by the Equatorial Plasma Bubbles (EPB - Barros et al, 2018) (Moraes et al, 2018).…”

Section: Studies Conducted Bymentioning

confidence: 99%

“…A consequence of the combination of these movements, leads to an increase in ionization in regions close to ± 15 ° of magnetic latitude, being that in the geomagnetic equator it is less intense (Basu et al, 2002, Moraes et al, 2018. Such enhancements are commonly referred to as the northern and southern crest of the Equatorial Ionization Anomaly (EIA), respectively (Cesaroni et al, 2015;Moreno et al, 2011).…”

Section: Ionosphere and Its Effects On Positioningmentioning

confidence: 99%

Evaluation of the GNSS Positioning Performance Under Influence of the Ionospheric Scintillation

Caldeira

Cereja

et al. 2020

Bol. Ciênc. Geod.

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The ionosphere may not only degrade the accuracy of the GNSS positioning but also reduce its availability because there is a high dependence between signal losses and ionospheric irregularities. Irregularities in the Earth's ionosphere may produce rapid fluctuations in phase and amplitude. These rapid fluctuations are called ionospheric scintillation. Thus, loss of signal can occur due to the effects of diffraction and refraction, which cause a weakening in the signal received by the GNSS receivers. In this way, this paper aims to evaluate the magnitude of ionospheric scintillation in Brazil and the performance of the positioning under its influence in the period of high solar activity in the current cycle (24), through the Spearman correlation analysis and the Wavelet periodogram. For that, three-year time series (2012 to 2014) of the S4 index and 3D MSE (Mean Squared Error) of three Brazilian stations with different ionospheric conditions were considered, PALM (near the Geomagnetic Equator) PRU2 (Equatorial region and Anomalies) and POAL (Mid-latitude region). Thus, it was possible to evaluate the correlation between the accuracy of the precise point positioning using only the C/A code of the GPS satellite and the S4 index. As a result, there was a correlation of 53% and 51%, using the Spearman method, for the PALM and PRU2 series, respectively. In addition, considering the analysis of space-frequency in relation to time by the Wavelet coherence method, a correlation of more than 70% is noted in the period of greatest 3D MSE concerning the spring and autumn equinox months.

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“…The plasma diffuses at low latitudes due to pressure gradients and gravity action. This phenomenon is known as the fountain effect (de Rezende et al 2007;Moraes et al 2018). That makes the Brazilian region an important location for research related to this issue.…”

Section: Ionospheric Effectmentioning

confidence: 99%

Generation and Performance Analysis of GPS and Glonass Virtual Data for Positioning Under Different Ionospheric Conditions

Jerez

Alves

2019

Bol. Ciênc. Geod.

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Several approaches concerning the use in positioning of GNSS (Global Navigation Satellite Systems) can be considered: systems, applied methods and errors that can affect the signals. Following the GLONASS (GLObal NAvigation Satellite System) constellation reestablishment (2011), there was renewed interest in its use with GPS (Global Positioning System). Different possibilities are available concerning applied methods, such as the virtual reference station (VRS) concept (it is possible to obtain data for a virtual station that does not physically exist, using data from a network). One of the main sources of error related to the GNSS signal, is the ionosphere. Many studies have been developed aiming to evaluate GPS positioning quality and influences that can affect it, but there are still several investigation possibilities concerning GLONASS. In this context, this research is intended to assess the GPS/GLONASS virtual data positioning performance considering regions and periods with different ionospheric behavior. A high correlation between the results from virtual and real data (Pearson's correlation coefficients around 0.8) was noticed. GPS/GLONASS data performance presented better mean squared error results compared to GPS alone (average 3D improvement was 45 cm-49%). In addition, it was possible to verify ionosphere influence in the positioning error, taking into account station region and period of the year.

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GPS availability and positioning issues when the signal paths are aligned with ionospheric plasma bubbles

Cited by 52 publications

References 34 publications

Ionospheric Scintillation Fading Coefficients for the GPS L1, L2, and L5 Frequencies

Ionospheric Scintillation Fading Coefficients for the GPS L1, L2, and L5 Frequencies

Evaluation of the GNSS Positioning Performance Under Influence of the Ionospheric Scintillation

Generation and Performance Analysis of GPS and Glonass Virtual Data for Positioning Under Different Ionospheric Conditions

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