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Journal Article•DOI•

Interfrequency Performance Characterizations of GPS During Signal Outages From an Anomaly Crest Location

Trisani Biswas1, S. Ghosh1, Ashik Paul1, Santu Sarkar1•
University of Calcutta1
01 Jun 2019-Space Weather-the International Journal of Research and Applications (John Wiley & Sons, Ltd)-Vol. 17, Iss: 6, pp 803-815
About: This article is published in Space Weather-the International Journal of Research and Applications.The article was published on 2019-06-01 and is currently open access. It has received 6 citations till now. The article focuses on the topics: Anomaly (natural sciences).
Citations
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Journal Article•DOI•
Investigating Ionospheric Scintillation Effects on Multifrequency GPS Signals

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Lucas A. Salles1, Bruno César Vani2, Alison de Oliveira Moraes3, Emanoel Costa4, Eurico R. de Paula5 •
Instituto Tecnológico de Aeronáutica1, São Paulo Federal Institute of Education, Science and Technology2, Aeronáutica3, Pontifical Catholic University of Rio de Janeiro4, National Institute for Space Research5
24 Apr 2021-Surveys in Geophysics
TL;DR: In this article, the authors analyzed the effect of ionospheric scintillation on the L2C and L5 GPS signals and compared their vulnerabilities with those of the L1 signal.
Abstract: Over the last 15 years, the satellite constellation of the global positioning system (GPS) has been modernized for more precise applications, with the introduction of the L2C and L5 signals. However, among other effects, they are susceptible to severe ionospheric effects, particularly in the equatorial and low-latitude regions. Equatorial plasma bubbles, resulting from the combination of the ionospheric electrodynamics with plasma instability mechanisms and thermospheric coupling, may generate irregularity structures with scale sizes ranging from hundreds of kilometers to a few meters (or less). Ionospheric irregularities may cause deep amplitude fades and phase shifts to transionospheric signals. That is, they are responsible for amplitude and phase scintillation, which degrade receiver operations and may cause failures and unavailability to positioning and navigation services under extreme conditions. The objective of the present work is to analyze ionospheric scintillation effects on the L2C and L5 GPS signals, to compare their vulnerabilities with those of the L1 signal. The data used in this analysis were collected between November 2014 and March 2015, during the maximum solar activity of cycle 24 (a period of great scintillation incidence), by scintillation monitors deployed at four different sites in the Brazilian territory: Fortaleza, Presidente Prudente, Sao Jose dos Campos, and Porto Alegre. Intensity fades will be analyzed, considering different thresholds, to reveal their empirical probability distributions of scintillation occurrence, average fading occurrences and durations. The results will show that greater probabilities of strong scintillation occurrences are present in the modernized signals, reaching up to five times more events in the L5 signal in comparison with those in the legacy L1 signal. It will be shown that the L5 average fade duration is distinctly longer than the corresponding ones for the other frequencies, considering the same site, threshold, and L1 amplitude scintillation level. The results will also show that the average fade duration decreases according to the average ratio 0.6 s/3 dB within the threshold range from − 6 to − 15 dB, considering the same amplitude scintillation level and location.

15 citations

Journal Article•DOI•
Examining the Tolerance of GNSS Receiver Phase Tracking Loop Under the Effects of Severe Ionospheric Scintillation Conditions Based on Its Bandwidth

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Igor Ponte Portella, Alison de Oliveira Moraes1, Marcelo da Silva Pinho2, Jonas Sousasantos2, Fabiano S. Rodrigues3 •
Aeronáutica1, Instituto Tecnológico de Aeronáutica2, University of Texas at Dallas3
01 Jun 2021-Radio Science
TL;DR: In this paper, the performance of phase-locked loop (PLL) under the presence of distinct scintillation patterns in the signal was evaluated using 54 different combinations of these parameters and the analysis showed that, among the configurations tested, the equivalent noise bandwidth of 10 Hz achieved the best performance overall.
Abstract: This study aims to evaluate the performance of phase-locked loop (PLL) under the presence of distinct scintillation patterns in the signal. Scintillation is very common in low-latitude regions due to the ionospheric dynamics. Under strong scintillation scenario the occurrence of deep fading events is usually registered and may cause severe degradation in the communication. The investigation conducted in this study uses the amplitude scintillation index S 4 , the decorrelation time τ 0 , and the bandwidth B n as main parameters. The study evaluates 54 different combinations of these parameters. The results indicate that in order to minimize the occurrence of cycle slips in the output phase of the PLL, the most appropriate tracking loop bandwidth B n depends on the values of both S 4 and τ 0 , which characterize the scintillation fading pattern. Simulations showed that as the S 4 index increases, the automatic increment in the PLL bandwidth may not be the best choice as the performance depends on the temporal characteristics of the scintillating signal. The analysis showed that, among the configurations tested, the equivalent noise bandwidth of 10 Hz achieved the best performance overall. The investigation also showed that choosing the wrong parameter regarding the PLL bandwidth may increase the probability of cycle slip by up to 10 times during fading events.

7 citations

Cites background from "Interfrequency Performance Characte..."

  • ...Besides spatial gradients, larger in the anomaly crest region (Biswas et al., 2019), the EPBs dynamic features may also play a significant role in the signal outage events (DasGupta et al....

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Journal Article•DOI•
Degradation of Satellite‐Based Navigation Performance Observed From an Anomaly Crest Location in the Indian Longitude Sector

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Samiddha Goswami1, S. Ray1, Ashik Paul1•
University of Calcutta1
01 Aug 2020-Radio Science

7 citations

Cites background or methods from "Interfrequency Performance Characte..."

  • ...The results presented in this paper correspond to some of the most intense cases of amplitude and phase scintillations observed from Calcutta located around the northern crest of EIA in the Indian longitudes during March 2014....

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  • ...In addition, there have been previous reports from this station where an elevation cutoff angle of 15° has been used (Biswas et al., 2019; Das et al., 2014; Goswami et al., 2018; Paul et al., 2017; Ray et al., 2017; Roy & Paul, 2013)....

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  • ...Analyses of amplitude and phase data observed from Calcutta have been done for the entire month of March 2014....

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  • ...A good correspondence is observed between the variation of σϕ in Figure 5b and the phase fluctuation plot in Figure 3d. Figure 6 shows the amplitude and phase scintillation indices plotted for all the satellites for the postsunset hours of 1 March 2014 during 12:00–24:00 UT observed from Calcutta....

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  • ...Figure 2 shows the variation of elevation angle and S4 as a function of Universal Time on different GPS links as observed from Calcutta on 1 March 2014 which is available to authorized users on the website (http://capricorn.bc.edu/scinda/india)....

    [...]

Journal Article•DOI•
A deep fading assessment of the modernized L2C and L5 signals for low-latitude regions

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Lucas A. Salles1, Alison de Oliveira Moraes2, Bruno César Vani, Jonas Sousasantos1, Bruno J. Affonso1, Bruno J. Affonso3, João Francisco Galera Monico4 •
Instituto Tecnológico de Aeronáutica1, Aeronáutica2, Embraer3, Sao Paulo State University4
01 Jul 2021-Gps Solutions
TL;DR: In this paper, a characterization of deep power fades is performed supported by a dataset covering 5 months of high-rate monitoring data collected at four different locations in Brazil in distinct S4 scenarios for the three available frequencies.
Abstract: When plasma instabilities arise in the post-sunset time, the so-called ionospheric plasma bubbles may develop, causing amplitude fades and phase oscillations, decreasing the availability and quality of transionospheric communication systems. In the regions where these bubbles appear, deep signal fading may occasionally reach the lowest levels and with loss of signal received for a certain period. In this work, a characterization of deep power fades is performed supported by a dataset covering 5 months of high-rate monitoring data collected at four different locations in Brazil in distinct S4 scenarios for the three available frequencies. Two aspects of the deep fading events were evaluated, the deepest fading attained per minute and the fading events deeper than −15 dB. The inter-frequency analysis showed that as S4 increases, the number of −15 dB fading occurrences increases for all bands and stations. The average number of occurrences reached approximately 7 and 9 cases per minute, respectively, for Presidente Prudente and Sao Jose dos Campos. Statistical analysis for fading events deeper than −15 dB obtained probabilities of 1.61%, 2.87% and 3.97%, respectively, for L1, L2C and L5 at Presidente Prudente. Regarding the value of the deepest fading event per minute, the larger difference between L1, L2C and L5 exhibits values around −11 dB at Presidente Prudente. For this station, the average deepest fading values achieved in L2C and L5 bands were nearly twice that of the L1. The results regarding the probability of a deepest fading less than −20 dB per minute for L5 signal present a probability of 1.38% in Fortaleza, while for Presidente Prudente and Sao Jose dos Campos, these values were 5.62% and 3.34%.

5 citations

Journal Article•DOI•
Signal-In-Space Performance Under Multiconstellation Environment From an Indian Low Latitude Station

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Trisani Biswas1, Ashik Paul1•
University of Calcutta1
01 Apr 2021-Radio Science

1 citations

References
More filters
Book•
GNSS -- global navigation satellite systems : GPS, GLONASS, Galileo, and more

[...]

Bernhard Hofmann-Wellenhof, Herbert Lichtenegger, Elmar Wasle
01 Jan 2008
TL;DR: The next generation of positioning models for positioning and data processing will depend on the design of the satellite itself, as well as on the satellite orbits it is placed in.
Abstract: Reference systems.- Satellite orbits.- Satellite signals.- Observables.- Mathematical models for positioning.- Data processing.- Data transformation.- GPS.- Glonass.- Galileo.- More on GNSS.- Applications.- Conclusion and outlook.

893 citations

Journal Article•DOI•
Global morphology of ionospheric scintillations

[...]

J. Aarons, Herbert E. Whitney, R.S. Allen
01 Feb 1971
TL;DR: In this article, a review of the available amplitude and phase scintillation data is presented, where the effect of magnetic activity, solar sunspot cycle, and time of day is shown for each three latitudinal sectors.
Abstract: Starting with post World War II studies of fading of radio star sources and continuing with fading of satellite signals of Sputnik, vast quantities of data have built up on the effect of ionospheric irregularities on signals from beyond the F layer. The review attempts to organize the available amplitude and phase scintillation data into equatorial, middle-, and high-latitude morphologies. The effect of magnetic activity, solar sunspot cycle, and time of day is shown for each of these three latitudinal sectors. The effect of the very high levels of solar flux during the past sunspot maximum of 1979-1981 is stressed. During these years unusually high levels of scintillation were noted near the peak of the Appleton equatorial anomaly (∼ ±15° away from the magnetic equator) as well as over polar latitudes. New data on phase fluctuations are summarized for the auroral zone with its sheet-like irregularity structure. One model is now available which will yield amplitude and phase predictions for varying sites and solar conditions. Other models, more limited in their output and use, are also available. The models are outlined with their limitations and data bases noted. New advances in morphology and in understanding the physics of irregularity development in the equatorial and auroral regions have taken place. Questions and unknowns in morphology and in the physics of irregularity development remain. These include the origin of the seeding sources of equatorial irregularities, the physics of development of auroral irregularity patches, and the morphology of F-layer irregularities at middle latitudes.

572 citations

"Interfrequency Performance Characte..." refers background in this paper

  • ...Dependence of the intensity of amplitude scintillations on solar flux variations, specifically near the northern crest of EIA have previously been reported by Aarons (1982) indicating higher scintillation intensity during periods of high solar flux....

    [...]

  • ...The equatorial ionosphere is characterized by generation of intense irregularities in electron density distribution, particularly during the postsunset hours of equinoctial months, leading to formation of field aligned plasma bubbles in the F region of the ionosphere (Aarons, 1982; Anderson & Haerendel, 1979)....

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  • ...Dependence of the intensity of amplitude scintillations on solar flux variations, specifically near the northern crest of EIA have previously been reported by Aarons (1982) indicating higher scintillation intensity during periods of high solar flux. The present analyses have found longer durations of loss of lock on GPS signals during February (monthly SSN: 146.1; F10.7 varies from 147.9 SFU to 188.1 SFU) than March (monthly SSN: 128.7; F10.7 varies from 134.2 SFU to 162.5 SFU) and April (monthly SSN: 112.5; F10.7 varies from 119.6 SFU to 185.2 SFU) depicting the effect of solar flux variation on the event, during the year 2014, which is consistent with Aarons (1982). The maximum value of loss of lock observed on SV1 at L2C is 8....

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Journal Article•DOI•
Plasma bubbles and irregularities in the equatorial ionosphere

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J. P. McClure, W. B. Hanson, J. H. Hoffman
01 Jul 1977-Journal of Geophysical Research
TL;DR: This paper observed large-scale (10 to 200-km) irregular biteouts of up to three orders of magnitude in the ion concentration in the nighttime equatorial F region associated with small-scale inhomogeneities in ion concentration.
Abstract: The Atmosphere Explorer satellite observed large-scale (10 to 200-km) irregular biteouts of up to three orders of magnitude in the ion concentration in the nighttime equatorial F region associated with small-scale inhomogeneities in the ion concentration. Simultaneous plasma velocity observations show irregular upward and westward motion of the order of 150 m/s associated with some of these 'bubbles', while others move more slowly or move with approximately the velocity of the background plasma. The plasma composition signatures indicate that most of the bubbles observed have recently moved upward. Several features of recent VHF radar observations can be understood as resulting from these plasma bubbles, e.g., the 'plume' features and very high apparent velocities seen on range-time-intensity spread F maps and the very complex and/or wide spectral features observed using such radars.

386 citations

"Interfrequency Performance Characte..." refers background in this paper

  • ...The diurnal and day‐to‐day variabilities of the equatorial ionosphere and particularly the Equatorial Ionization Anomaly (EIA) is a phenomenon well studied in literature (Basu et al., 2009; Bhattacharyya et al., 2003; Kelley et al., 1976; McClure et al., 1977; Paul & DasGupta, 2010; Rastogi & Klobuchar, 1990)....

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  • ...…and day‐to‐day variabilities of the equatorial ionosphere and particularly the Equatorial Ionization Anomaly (EIA) is a phenomenon well studied in literature (Basu et al., 2009; Bhattacharyya et al., 2003; Kelley et al., 1976; McClure et al., 1977; Paul & DasGupta, 2010; Rastogi & Klobuchar, 1990)....

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Journal Article•DOI•
Ionospheric electron content within the equatorial F 2 layer anomaly belt

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R. G. Rastogi, J. A. Klobuchar
01 Nov 1990-Journal of Geophysical Research
TL;DR: In this article, the presence or absence of the latitudinal anomaly in TEC on a particular day depended only on the strength of the electrojet current, as determined by the difference of the horizontal magnetic field at stations on the magnetic equator and stations outside the equatorial electrojet.
Abstract: Results are presented on continuous TEC measurements, taken along a chain of stations spaced between 0 deg N and 25 deg N and aligned roughly along the same longitude sector in India, that describe the day-to-day behavior of the location of equatorial anomaly in the TEC during the period of the 1975-1976 sunspot minimum, when the ATS spacecraft was visible from India. It was found that the presence or absence of the latitudinal anomaly in TEC on a particular day depended only on the strength of the electrojet current, as determined by the difference of the horizontal magnetic field at stations on the magnetic equator and stations outside the equatorial electrojet, rather than on the horizontal magnetic field measured only at equatorial stations.

222 citations

"Interfrequency Performance Characte..." refers background in this paper

  • ...…and day‐to‐day variabilities of the equatorial ionosphere and particularly the Equatorial Ionization Anomaly (EIA) is a phenomenon well studied in literature (Basu et al., 2009; Bhattacharyya et al., 2003; Kelley et al., 1976; McClure et al., 1977; Paul & DasGupta, 2010; Rastogi & Klobuchar, 1990)....

    [...]

Journal Article•DOI•
A new automated cycle slip detection and repair method for a single dual-frequency GPS receiver

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Zhizhao Liu1•
Hong Kong Polytechnic University1
01 Mar 2011-Journal of Geodesy
TL;DR: This new algorithm can detect and correctly repair almost any cycle slips even under very high level of ionospheric activities and is suitable for many applications where one single receiver is used, e.g. real-time kinematic rover station and precise point positioning.
Abstract: This paper develops a new automated cycle slip detection and repair method that is based on only one single dual-frequency GPS receiver. This method jointly uses the ionospheric total electron contents (TEC) rate (TECR) and Melbourne–Wubbena wide lane (MWWL) linear combination to uniquely determine the cycle slip on both L1 and L2 frequencies. The cycle slips are inferred from the information of ionospheric physical TECR and MWWL ambiguity at the current epoch and that at the previous epoch. The principle of this method is that when there are cycle slips, the MWWL ambiguity will change and the ionospheric TECR will usually be significantly amplified, the part of artificial TECR (caused by cycle slips) being significantly larger than the normal physical TECR. The TECR is calculated based on the dual-frequency carrier phase measurements, and it is highly accurate. We calculate the ionospheric change information (including TECR and TEC acceleration) using the previous epochs (30 epochs in this study) and use the previous data to predict the TECR for the epoch needing cycle slip detection. If the discrepancy is larger than our defined threshold 0.15 TECU/s, cycle slips are regarded to exist at that epoch. The key rational of method is that during a short period (1.0 s in this study) the TECR of physical ionospheric phenomenon will not exceed the threshold. This new algorithm is tested with eight different datasets (including one spaceborne GPS dataset), and the results show that the method can detect and correctly repair almost any cycle slips even under very high level of ionospheric activities (with an average Kp index 7.6 on 31 March 2001). The only exception of a few detected but incorrectly repaired cycle slip is due to a sudden increased pseudorange error on a single satellite (PRN7) under very active ionosphere on 31 March 2001. This method requires dual-frequency carrier phase and pseudorange data from only one single GPS receiver. The other requirement is that the GPS data rate ideally is 1 Hz or higher in order to detect small cycle slips. It is suitable for many applications where one single receiver is used, e.g. real-time kinematic rover station and precise point positioning. An important feature of this method is that it performs cycle slip detection and repair on a satellite-by-satellite basis; thus, the cycle slip detection and repair for each satellite are completely independent and not affected by the data of other satellites.

190 citations

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