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Ionospheric scintillation effects on GPS measurements and algorithms to improve positioning solution accuracy

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dc.contributor.authorMyer, Gregory Thomas, author
dc.contributor.authorMorton, Y. T. Jade, advisor
dc.contributor.authorWilson, Jesse, committee member
dc.contributor.authorShonkwiler, Clayton, committee member
dc.date.accessioned2017-09-14T16:07:02Z
dc.date.available2017-09-14T16:07:02Z
dc.date.issued2017
dc.description.abstractThe ionosphere is an important cause of disturbances on GNSS signals, especially in high latitudes and equatorial areas. Previous studies indicate that while ionospheric scintillation may cause abrupt, random fluctuations in carrier phase measurements, its impact on pseudorange is less serious. Since modern GNSS receivers, especially those for high precision applications, use carrier phase-smoothed pseudoranges to improve accuracy of position solutions, there exists the need to have a better understanding of the scintillation effects on carrier phase measurements and developing means to mitigate scintillation induced errors in navigation solutions. In this thesis, scintillation impacts are demonstrated on carrier phase and pseudorange measurements using real scintillation data collected at high latitudes and equatorial areas, and the effect on positioning is investigated and mitigated. To obtain a more insightful and quantitative understanding of the impact, the data was used to generate position solutions using standard navigation processing algorithms. The results clearly indicate that sudden carrier phase discontinuities during strong scintillation lead to the degradation of carrier-smoothed pseudorange accuracy and consequently, results in large position errors. During strong scintillation with no carrier phase discontinuities, comparatively smaller position errors are found due to phase fluctuations that cause small changes in the range measurements. Based on this analysis, we give examples of several approaches to mitigate these problems, and use these approaches to present adaptive positioning techniques to mitigate scintillation induced position errors. One algorithm simply replaces the carrier-smoothed pseudorange with the unsmoothed pseudorange for satellites that are affected by outages on the carrier phase measurements, or if strong scintillation is detected. Another adaptive algorithm uses the GDOP to determine if a scintillating satellite can be completely removed from the navigation processing to improve positioning accuracy. Results show that the algorithms that substitute the unsmoothed pseudorange increase errors by 24.5% as compared to a conventional technique that repairs cycle slips, which indicates that it is still best to use the carrier-smoothed pseudoranges as long as there are no discontinuities. Results from the adaptive technique based on the analysis of the GDOP show a reduction of maximum errors on average by 13% on all of the data sets when comparing to a conventional algorithm. It was also found that a new carrier-smoothing technique can reduce maximum errors by 7.9% on average. Alternative approaches for future improvements are also discussed.
dc.format.mediumborn digital
dc.format.mediummasters theses
dc.identifierMyer_colostate_0053N_14428.pdf
dc.identifier.urihttps://hdl.handle.net/10217/184049
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2000-2019
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.subjectGPS
dc.subjectscintillation
dc.subjectpositioning
dc.subjectGNSS
dc.titleIonospheric scintillation effects on GPS measurements and algorithms to improve positioning solution accuracy
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineElectrical and Computer Engineering
thesis.degree.grantorColorado State University
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (M.S.)

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