Дисертації з теми "Scintillation-Ionospheric"
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Jiao, Yu. "High Latitude Ionospheric Scintillation Characterization." Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1376909513.
Повний текст джерелаHo, Yih Hwa. "Mitigation of ionospheric scintillation effects on GNSS." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539702.
Повний текст джерелаMoraes, Alison de Oliveira. "Advances in statistical modeling of ionospheric scintillation." Instituto Tecnológico de Aeronáutica, 2013. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=2240.
Повний текст джерелаBurston, Robert. "Investigating ionospheric scintillation mechanisms via theory and experimentation." Thesis, University of Bath, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516941.
Повний текст джерелаKnight, Mark Frederick. "Ionospheric scintillation effects on global positioning system receivers." Title page, contents and abstract only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phk698.pdf.
Повний текст джерелаBoryczko, Marta, and Tomasz Dziendziel. "Optimisation Of Ionospheric Scintillation Model Used In Radio Occultation." Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-11915.
Повний текст джерелаAtilaw, Tsige Yared. "Characterization of the Multipath Environment of Ionospheric Scintillation Receivers." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/16475.
Повний текст джерелаGlobal Navigation Satellite Systems (GNSS) are used to provide information on position, time and velocity all over the world at any time of the day. Currently there are four operational GNSS and one of them is GPS (Global Positioning System) that is developed and maintained by U.S Department of Defence (DoD), which is widely used and accessible all over the world. The accuracy of the output or even the availability of the navigation system depends on current space weather conditions, which can cause random fluctuations of the phase and amplitude of the received signal, called scintillation. Interference of GNSS signals that are reflected and refracted from stationary objects on the ground, with signals that travel along a direct path via the ionosphere to the antenna, cause errors in the measured amplitude and phase. These errors are known as multipath errors and can lead to cycle slip and loss of lock on the satellite or degradation in the accuracy of position determination. High elevation cut off angles used for filtering GNSS signals, usually 15-30°, can reduce non-ionospheric interference due to multipath signals coming from the horizon. Since a fixed-elevation threshold does not take into consideration the surrounding physical environment of each GPS station, it can result in a significant loss of valuable data. Alternatively, if the fixed-elevation threshold is not high enough we run the risk of including multipath data in the analysis. In this project we characterized the multipath environment of the GPS Ionospheric Scintillation and TEC (Total Electron Content) Monitor (GISTM) receivers installed by SANSA (South African National Space Agency) at Gough Island (40:34oS and 9:88° W), Marion Island (46:87° S and 37:86° E), Hermanus (34:42° S and19:22° E) and SANAE IV (71:73° S and 2:2° W) by plotting azimuth-elevation maps of scintillation indices averaged over one year. The azimuth-elevation maps were used to identify objects that regularly scatter signals and cause high scintillation resulting from multipath effects. After identifying the multipath area from the azimuth-elevation map, an azimuth-dependent elevation threshold was developed using the MATLAB curve fitting tool. Using this method we are able to reduce the multi-path errors without losing important data. Using the azimuth-dependent elevation threshold typically gives 5 to 28% more useful data than using a 20° fixed-elevation threshold.
Kumagai, Hiroshi. "Mid-latitude ionospheric irregularities deduced from spacedreceiver scintillation measurements." Kyoto University, 1988. http://hdl.handle.net/2433/162220.
Повний текст джерелаRomano, Vincenzo. "Ionospheric scintillation effects on GNSS : monitoring and data treatment development." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/33909/.
Повний текст джерелаKinrade, Joe. "Ionospheric imaging and scintillation monitoring in the Antarctic and Arctic." Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619217.
Повний текст джерелаOlivarez, Nathan. "Mitigating the Effects of Ionospheric Scintillation on GPS Carrier Recovery." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/245.
Повний текст джерелаPraveen, Vikram. "Event Driven GPS Data Collection System for Studying Ionospheric Scintillation." Miami University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1323894410.
Повний текст джерелаCarroll, Mark Joseph. "Advanced GPS Receiver Algorithms for Assured Navigation During Ionospheric Scintillation." Miami University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=miami1399602874.
Повний текст джерелаBrosie, Kayla Nicole. "Ionospheric Scintillation Prediction, Modeling, and Observation Techniques for the August 2017 Solar Eclipse." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78710.
Повний текст джерелаMaster of Science
Locubiche-Serra, Sergi. "Robust Carrier Tracking Techniques for GNSS Receivers affected by Ionospheric Scintillation." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/668304.
Повний текст джерелаGlobal Navigation Satellite Systems (GNSS) have become an indispensable tool in different areas in our modern society for positioning purposes using radio-frequency ranging signals. Some application examples are the positioning and navigation in ground, maritime and aviation environments, as well as their use in agriculture, surveying and precise timing and synchronization in communication systems and finances. The tracking stage is one of the core tasks within a GNSS receiver to keep aligned with the satellites and, to date, most receivers equip conventional tracking techniques with ease of implementation that suffice to operate in environments with favorable working conditions. However, in the recent years, the success of GNSS in open-sky environments has led to the emergence of applications that expand toward scenarios with harsher conditions, such as urban canyons and soft-indoor environments. The trend is to provide user mobile terminals such as smartphones with positioning capabilities in scenarios where receivers face new technological challenges owing to the abounding propagation impairments. In this sense, the so-called ionospheric scintillation is one of the issues degrading the performance of GNSS receivers, particularly in equatorial regions and at high latitudes. It introduces rapid carrier phase and signal power variations, and has a detrimental effect particularly onto the tracking stage. The objective of this thesis is to design and develop new techniques for the robust tracking of GNSS signals affected by ionospheric scintillation disturbances. The presented approach is based on the use of Kalman filtering techniques, and the main contributions of the thesis are three. First, the analysis of ionospheric scintillation and the tracking of carrier dynamics despite the presence of the former. We design a Kalman filter with a hybrid formulation that allows the robust monitoring of both contributions separately. This arises from carrying out a detailed analysis of ionospheric scintillation which concludes that scintillation phase variations can be characterized through autoregressive processes, and thus be dealt with within the Kalman filter in a natural manner. Second, the design of adaptive Kalman filter-based techniques that allow self-adjusting their loop bandwidth to the actual scintillation conditions, which are rather time-varying in practice. This part includes a scintillation detector, a real-time estimator of the autoregressive model parameters, and an implementation to address the problem of non-linear signal amplitude attenuation introduced by scintillation itself. The goodness of the proposed techniques is later validated by carrying out an extensive simulation campaign using both synthetic data and real scintillation time series, and the outperformance region with respect to conventional tracking techniques is quantified. Third, a novel method for the derivation of expressions for the termed Bayesian Cramér-Rao bound (BCRB), which allow characterizing the behavior of Kalman filters in a closed-form manner, thus becoming a contribution to the literature of practical usefulness to design Kalman filters for any kind of application.
Xu, Dongyang. "BEIDOU AND GPS DUAL CONSTELLATION VECTOR TRACKING DURING IONOSPHERE SCINTILLATION AT EQUATORIAL REGION." Miami University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=miami1407512226.
Повний текст джерелаJerez, Gabriel Oliveira [UNESP]. "Análise da integração GPS/GLONASS para posicionamento sob efeito de cintilação ionosférica." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150286.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Com o desenvolvimento dos sistemas globais de navegação por satélite as atividades que envolvem posicionamento passaram por uma revolução. Os pioneiros, GLONASS (GLObal NAvigation Satellite System) e GPS (Global Positioning System), são atualmente os principais sistemas, e únicos com constelação completa. A utilização combinada de dados GPS e GLONASS passou por uma perda de interesse no final da década de noventa devido à rápida degradação que o GLONASS sofreu. Porém, em 2001 teve início um plano de restabelecimento do sistema que em 2011 voltou a contar com constelação completa de 24 satélites e cobertura global. O GLONASS passa ainda por um processo de modernização, com novas gerações de satélites sendo desenvolvidas, refinamentos dos sistemas de tempo e referência e novas estações de controle sendo instaladas. Além do uso de dados combinados, outros fatores que influenciam a qualidade do posicionamento são os métodos empregados e os erros aos quais os sinais transmitidos estão sujeitos. Nas metodologias de integração devem constar as diferenças de estrutura dos sistemas, sendo as principais, para este caso, os sistemas de referência, sistemas de tempo e a tecnologia relacionada às frequências. Em relação aos erros, a ionosfera é uma importante fonte, principalmente para usuários de receptores de apenas uma frequência. Ela exige atenção especial, pois além de degradar a acurácia do posicionamento há uma grande dependência entre perdas do sinal e irregularidades ionosféricas, como a cintilação ionosférica. Na presente pesquisa buscou-se analisar as melhorias apresentadas no posicionamento utilizando dados combinados GPS/GLONASS sob efeito de cintilação ionosférica, avaliar a influência da cintilação nos sinais GLONASS e realizar um estudo da estrutura do sistema. Foram realizados três experimentos, relacionados à aplicação do PPP (Posicionamento por Ponto Preciso), do posicionamento relativo estático e do posicionamento em redes (especificamente no conceito de VRS – Virtual Reference Station). Para possibilitar o posicionamento em redes foi adaptada a ferramenta VRS-UNESP, para permitir a geração de bases virtuais com dados GLONASS ou GPS/GLONASS. Para as três metodologias foram selecionadas estações em três regiões do Brasil com comportamentos ionosféricos distintos visando possibilitar também a análise do efeito da cintilação. Para isso foram escolhidas regiões próximas ao equador geomagnético, próximas a área afetada pelo efeito fonte e ao sul do país, onde se tem menor influência da ionosfera. Para o PPP considerando-se todos os casos, independente da configuração, houve melhoria em 92,28% dos dias com o uso de dados GPS e GLONASS. Para o posicionamento relativo os resultados obtidos foram mais irregulares que para o PPP, sendo que a melhoria ocorreu em 69,18% dos casos. Os dados virtuais foram processados de maneira análoga ao experimento com PPP, obtendo melhoria em 100% os casos analisados ao se utilizar dados GPS e GLONASS.
With the development of the Global Navigation Satellite Systems (GNSS) the activities involving positioning passed by a great revolution. Currently, the pioneers, GLONASS (GLObal NAvigation Satellite System) and GPS (Global Positioning System), are the main systems with full constellation. The interest in the combined use of GPS and GLONASS data had a great fall in the late nineties due to the fast degradation of GLONASS. However, in 2001 a restoration plan of the system began and in 2011 GLONASS recovered the full constellation of 24 satellites with global coverage. Furthermore GLONASS is going through a modernization process, with the development of new satellite generations, time and reference systems refinements and new control stations. Besides the use of combined data, other factors that influence the positioning quality are the applied methods and the errors that can affect the transmitted signals. The integration methodologies must consider the differences in the systems structures, the main differences, for this case, are reference and time systems and the technology related to the frequencies. About the errors, the ionosphere is an important source, mainly for users of single frequency receivers. It requires special attention, because besides of degrading the positioning accuracy there is a great dependency between the loss of signal and ionospheric irregularities, as ionospheric scintillation. In this research it was intended to analyze the improvement of the combined use of GPS/GLONASS data at positioning under ionospheric scintillation effect, evaluate the influence of scintillation at GLONASS signals and perform a study about the structure of the system. Three experiments were performed, the first one is related to the application of PPP (Precise Point Positioning), the second one is about static relative positioning and the third one is about network based positioning (specifically in the Virtual Reference Station concept).To enable the network based positioning the software VRS-UNESP was adapted, in order to allow the generation of virtual stations with GLONASS or GPS/GLONASS data. In the three methodologies were selected three regions of Brazil with distinct ionospheric behavior, in order to evaluate the scintillation effect in the positioning. It was selected regions near to the geomagnetic equator, regions near the fountain effect and in the south of the country, where the ionosphere effect is less intense. For the PPP, considering all the configurations adopted, there was improvement with the use of GPS and GLONASS combined data in 92,28% of the days analyzed. For the relative positioning the results obtained were more irregulars than the ones from PPP. In such case it was achieved improvement in 69,18% of the cases with the use of combined data. The virtual data were processed in a procedure similar to the one used in the PPP experiment. It was achieved improvement in 100% of the cases that were used GPS and GLONASS data.
Silva, Heloísa Alves da [UNESP]. "Avaliação de modelos estocásticos no posicionamento GNSS." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/86784.
Повний текст джерелаCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Atualmente, o GNSS, em especial o GPS, é uma das tecnologias mais utilizadas para realizar posicionamento. Os modelos funcionais relacionados com as observações GNSS são mais conhecidos do que os modelos estocásticos, visto que o desenvolvimento destes últimos é mais complexo. Normalmente, no posicionamento GNSS são utilizados modelos estocásticos numa forma simplificada, com um modelo padrão, o qual assume que todas as medidas das observações GNSS têm a mesma variância e são estatisticamente independentes. Porém, atualmente os modelos estocásticos relacionados ao GNSS vêm sendo pesquisados com maior profundidade, por exemplo, considerando efeitos de cintilação ionosférica. Este efeito pode ser considerado na modelagem estocástica já que atualmente receptores GNSS permitem a extração de parâmetros de cintilação ionosférica. Além dessa, outro tipo de modelagem estocástica pode ser realizada, no caso, trata-se da consideração da variação dos ângulos de elevação dos satélites durante o rastreio dos dados. Sendo assim, nessa pesquisa foram desenvolvidos e analisados esses dois casos de modelagem estocástica, tanto no posicionamento relativo, quanto no absoluto (por ponto). No posicionamento relativo, ao se considerar a modelagem estocástica em função da cintilação ionosférica, os resultados atingiram melhorias em torno de 93,0% em relação à modelagem padrão. No processamento e análise foram utilizados dados GPS coletados no Norte da Europa, os quais estão sob condições de cintilação ionosférica. No posicionamento relativo considerando a modelagem estocástica em função dos ângulos de elevação dos satélites, as melhorias foram em torno de 89,2%. No caso do posicionamento por ponto, as melhorias em relação a modelagem estocástica padrão atingiram valores de aproximadamente 45,1% e 42,1% considerando, respectivamente...
Nowadays, the GNSS, especially the GPS, is one of the most used techniques to accomplish positioning. The functional models related with the GNSS observables are more known than the stochastic models, considering that the development of the last ones is more complex. Usually, they are used in a simplified form, as the standard model, which assumes that all the GNSS observable have the same variance and are statistically independent. However, the stochastic models are being investigated with more property, for example, considering the ionospheric scintillation effects. This effect can be considered in the stochastic modelling since now receivers GNSS allow the extraction of ionospheric scintillation parameters. Besides that, others stochastic modelling can be accomplished, e.g. considering the variation of the satellites elevation angles during the data tracking. Thus, in this dissertation it was investigated the two cases of stochastic modelling cited above, either in the relative or in the absolute positioning... (Complete abstract click electronic access below)
Vani, Bruno César [UNESP]. "Investigações sobre modelagem, mitigação e predição de cintilação ionosférica na região brasileira." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/153701.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Cintilações Ionosféricas são rápidas variações na amplitude e/ou fase de um sinal de rádio ao se propagar por irregularidades na densidade de elétrons na ionosfera. Este fenômeno degrada a performance do posicionamento pelo GNSS, uma vez que pode acarretar, dentre outros aspectos, a degradação na acurácia de observáveis e em perdas de sincronismo no receptor. No Brasil, verifica-se a maior suscetibilidade de ocorrência de cintilação algumas horas após o pôr-do-sol, nas épocas do ano compreendidas entre os equinócios de primavera e outono nos anos de alta atividade solar. Redes GNSS de monitoramento de cintilações estão implantadas no território brasileiro, incluindo a rede CIGALA/CALIBRA – a qual é mantida pela FCT/UNESP com o apoio de parceiros nos últimos sete anos. Os dados de monitoramento permitem a realização de diversas pesquisas sobre características e efeitos da cintilação, incluindo as investigações conduzidas neste projeto. Foram investigados aspectos sobre a modelagem da cintilação ionosférica no Brasil, com ênfase na mitigação dos seus efeitos no PPP e na predição de ocorrência de cintilação. No contexto da mitigação, abordagens existentes foram avaliadas e uma nova proposta foi desenvolvida. A abordagem proposta para mitigação consiste em um novo modelo funcional, novo modelo estocástico e uma estratégia para minimizar os efeitos de perdas de sincronismo. A abordagem proposta foi testada com o suporte do software científico RT-PPP e os resultados obtidos foram promissores, incluindo casos de recuperação da acurácia esperada do PPP, mesmo sob influência de cintilação forte. No contexto da predição, uma integração de bases de dados de monitoramento oriundos de três redes (CIGALA/CALIBRA, ICEA e LISN) permitiu o desenvolvimento de um modelo preditivo (guiado por dados) baseado em redes neurais artificiais. A rede neural é treinada para obter uma estimativa das localidades e horários onde a cintilação é esperada em uma determinada noite, com base em dados de monitoramento obtidos em noites anteriores. Dados de monitoramento de diferentes regiões coletados no começo da mesma noite (logo após o pôr-do-sol) também são utilizados com o objetivo de inferir padrões acerca do surgimento das irregularidades que causam as cintilações e sua relação com o nível de cintilação observado no restante da noite. O modelo permite obter mapas de cintilação preditos com antecedência de uma a quatro horas, os quais são acompanhados de estimativas de qualidade das predições. Em resumo, este projeto apresenta contribuições com potencial para trazer benefícios ao cenário científico-tecnológico nacional. Além disso, os dados de monitoramento da base de dados integrada foram disponibilizados pela internet à comunidade através do software científico ISMR Query Tool, proporcionando suporte à realização de pesquisas adicionais em diversas instituições do Brasil e do mundo.
Ionospheric scintillations are rapid variation in amplitude and/or phase of a radio signal as it propagates through irregularities on electron density in the ionosphere. Such phenomenon degrades the performance of GNSS positioning, because it may cause accuracy degradation on observables and losses of lock, among other aspects. In Brazil, there is more susceptibility to occurrence of scintillations after sunset time between the spring and autumn equinoxes of years with high solar activity. Monitoring networks based on GNSS receivers are deployed over the Brazilian territory such as the CIGALA/CALIBRA network, managed by FCT/UNESP (with support from partners) in the last seven years. Monitoring data allows to develop several research regarding the scintillation effects, as in this thesis. Aspects regarding the modeling of ionospheric scintillation effects in Brazil were investigated, with emphasis on the mitigation of these effects on PPP and predictions of scintillation occurence. In the field of mitigation, existing approaches were investigated and a new one was proposed. The new approach for mitigation relies in both new functional and stochastic models for PPP, as well as a strategy to model effects of losses of lock. The proposed approach was tested with the scientific software RT-PPP and the achieved results were promising, including cases in which the expected accuracy for the PPP was recovered. In the field of the predictions, a database integration was conducted with data from three different networks (CIGALA/CALIBRA, ICEA e LISN). The integration allowed the development of a data-driven predictive model based on artificial neural network. The neural network is trained with data from previous nights. Data from the same night (around the sunset time) is also used to detect patterns regarding the emerging of the irregularities driving scintillation occurrence on the whole night. The model allows to generate maps of predicted scintillation with antecedence from one to four hours. In summary, this thesis shows contributions with potential to create benefits on the scientific and technological scenarios in Brazil. Furthermore, monitoring data from the integrated database was made available to the scientific community via the software ISMR Query Tool, providing support to conduct new research in different institutions from Brazil and the world.
CAPES: 88881.134266/2016-01
Peng, Yuxiang. "GNSS-based Spacecraft Formation Flying Simulation and Ionospheric Remote Sensing Applications." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/79594.
Повний текст джерелаMaster of Science
Vermeulen, Annelie. "Identifying Ionospheric Scintillation in the South Atlantic Magnetic Anomaly using motion-affected GPS data from a ship-based receiver." Master's thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/31337.
Повний текст джерелаSilva, Heloísa Alves da. "Avaliação de modelos estocásticos no posicionamento GNSS /." Presidente Prudente : [s.n.], 2009. http://hdl.handle.net/11449/86784.
Повний текст джерелаAbstract: Nowadays, the GNSS, especially the GPS, is one of the most used techniques to accomplish positioning. The functional models related with the GNSS observables are more known than the stochastic models, considering that the development of the last ones is more complex. Usually, they are used in a simplified form, as the standard model, which assumes that all the GNSS observable have the same variance and are statistically independent. However, the stochastic models are being investigated with more property, for example, considering the ionospheric scintillation effects. This effect can be considered in the stochastic modelling since now receivers GNSS allow the extraction of ionospheric scintillation parameters. Besides that, others stochastic modelling can be accomplished, e.g. considering the variation of the satellites elevation angles during the data tracking. Thus, in this dissertation it was investigated the two cases of stochastic modelling cited above, either in the relative or in the absolute positioning... (Complete abstract click electronic access below)
Orientador: Paulo de Oliveira Camargo
Coorientador: João Francisco Galera Monico
Banca: Mauricio Alfredo Gende
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Mestre
Caldeira, Mayara Cobacho Ortega [UNESP]. "Análise do impacto do efeito ionosférico e cintilação ionosférica no Posicionamento Baseado em Redes e Por Ponto." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/144291.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Visando usufruir do potencial dos sistemas de posicionamento global existentes, novos métodos de posicionamento têm surgido e outros vêm sendo aprimorados. Uma grande tendência nos últimos anos tem sido o uso de redes de estações GNSS de referência. Mas, tanto no uso de redes como nos demais métodos, um fator importante para melhorar a qualidade do posicionamento está relacionado com a modelagem atmosférica. Especial atenção deve ser dada aos erros que ocorrem devido à ionosfera, pois ela se tornou a principal fonte de erro no posicionamento GNSS, após desativação da técnica SA. Este erro é diretamente proporcional ao Conteúdo Total de Elétrons (TEC) e inversamente proporcional ao quadrado da frequência do sinal. O TEC e, consequentemente, o erro ionosférico variam no tempo e no espaço, e sofrem diversas influências, como: ciclo solar, época do ano, hora local, localização geográfica, atividade geomagnética, entre outros. Atualmente, o os erros proporcionados pela ionosfera podem ter seus efeitos minimizados a partir de arquivos IONEX ou por meio de modelagem ionosférica. Portanto, nesta pesquisa, foram utilizados dados das estações da RBMC em diferentes regiões do Brasil no período de baixa e alta densidade de elétrons do pico solar 24 para avaliar o desempenho dos mapas ionosféricos, no posicionamento baseado em redes, disponibilizados por diversos centros (CODE, ESA, JPL, UPC e IGS), bem como os fornecidos pelo projeto MIMOSA, e também os modelos de Grade (AGUIAR, 2010) e estimativa de TEC. Para tal fim, foi adotado um sistema computacional desenvolvido na FCT/UNESP, denominado VRS-Unesp, que emprega o conceito de Estação Virtual. De acordo com os resultados obtidos, nota-se que não há um único mapa fornecido pelos centros de análise do IGS que melhor se enquadra a realidade brasileira, além disso, o desempenho do mapa depende das condições ionosféricas e, principalmente, da localização da estação. Além disso, verificou-se que a acurácia obtida pelo IONEX do projeto MIMOSA, pelo modelo de grade e de Estimativa do TEC que utilizam dados regionais e possuem maior resolução espacial e temporal, foram os que apresentaram os melhores resultados. Por fim foi avaliada a correlação entre a acurácia do posicionamento por ponto e o índice de cintilação S4, já que a ionosfera pode não apenas degradar a acurácia do posicionamento GNSS como reduzir sua disponibilidade, pois existe uma alta dependência entre perdas do sinal e irregularidades ionosféricas. Como resultado, considerando a análise de espaço-frequência em relação ao tempo pelo método coerência wavelets para avaliação da correlação da série, nota-se uma correlação no périodo do equinócio superior a 70%.
In order to take advantage from global positioning systems, new positioning methods have emerged and others have been improved. An important tendency in recent years has been the use of GNSS reference stations networks. But, using networks or other positioning methods an important factor to improve the positioning quality is related to atmospheric modeling. Special attention should be given to errors that occur due to ionosphere, it became the largest error source in GNSS positioning after disabling SA technique. Ionosphere error depends on signal frequency and Total Electron Content (TEC) in the ionospheric layer. TEC and consequently the ionospheric error varies regularly in time and space and they are affected by different sources like: sunspot number (solar cycle), season, local time, geographic position, geomagnetic activity, and others. Currently, the errors provided by the ionosphere can be minimized using IONEX files or models. Therefore, in this research, the RBMC stations data were used in different regions of Brazil in the period of low and high electron density of the cycle solar 24 to evaluate the performance of the ionospheric maps, in network-based positioning, available from several centers, as CODE , ESA, JPL, UPC and IGS, as well as those provided by the MIMOSA project, and also the Grade Models (AGUIAR, 2010) and TEC Estimates. For this, a computer system developed in FCT / UNESP has been adopted, RSV-Unesp that uses the concept of Virtual Station. According to the results, we note that there is not single map of IGS analysis centers that best fits the Brazilian reality, moreover, the map performance depends on the ionospheric conditions and, primarily, the station location. Moreover, it was found that the accuracy obtained by IONEX the MIMOSA project, the Grade Model and TEC estimation using regional data and have higher spatial and temporal resolution, showed the best results. Finally we evaluated the correlation between the accuracy of point positioning and scintillation index S4, since the ionosphere can not only degrade the accuracy of GNSS positioning as well as reduce its availability, because there is a high dependency between signal loss and ionospheric irregularities. As result, considering the space-frequency analysis with respect to time by the wavelet coherence method for evaluation of the correlation of the series, there is a correlation in the period of higher equinox to 70%.
FAPESP: 2014/03858-9
Galmiche, Aurélien. "Modélisation de la scintillation ionosphérique en zone équatoriale : application à l'inversion des signaux GNSS pour la caractérisation de la turbulence." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30053.
Повний текст джерелаThe ionosphere is an ionized medium, into which the spatio-temporal electronic density variations disrupt the electromagnetic waves propagation. The turbulent ionospheric plasma is in particular linked to rapid amplitude and phase fluctuations of the radio electric signals: this is the ionospheric scintillation phenomenon. Especially around the equatorial latitudes, systems needing great accuracy, availability and measurement integrity are particularly sensitive to its effects. This is the case of the positioning systems using the GNSS technology. The aim of this thesis is to exploit insightly the ionospheric scintillation effects on the signal in order to propose a turbulent ionosphere's characteristics sounding through GNSS measurements inversion. At first, the specificities of the ionosphere's plasma dynamics accounting for the scintillation effects are reminded. Then, from a spectral description of the electronic density's turbulent fluctuations, an analytic and a numeric model of the transionospheric propagation are introduced. They are completed by considering the GNSS receiver. This step finalizes the direct problem's modelization. A new GNSS data inversion algorithm is then come up with. Its intensive application to the SAGAIE database (collected in equatorial Africa) shows the invers approach's capacity to return various parameters describing the ionospheric turbulences
Nguyen, Thai Chinh [Verfasser], Harald [Akademischer Betreuer] Schuh, Mahdi [Akademischer Betreuer] Alizadeh, Harald [Gutachter] Schuh, Mahdi [Gutachter] Alizadeh, and Lung-Chih [Gutachter] Tsai. "Use of the East Asia GPS receiving network to observe ionospheric VTEC variations, scintillation and EIA features during the Solar Cycle 24 / Thai Chinh Nguyen ; Gutachter: Harald Schuh, Mahdi Alizadeh, Lung-Chih Tsai ; Harald Schuh, Mahdi Alizadeh." Berlin : Technische Universität Berlin, 2021. http://d-nb.info/1231908394/34.
Повний текст джерелаMohd, Ali Aiffah. "GNSS in aviation : ionospheric threats at low latitudes." Thesis, University of Bath, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.761026.
Повний текст джерелаLudwig, Barbosa Vinícius. "Effects of Small-Scale Ionospheric Irregularities on GNSS Radio Occultation Signals : Evaluations Using Multiple Phase Screen Simulator." Licentiate thesis, Blekinge Tekniska Högskola, Institutionen för matematik och naturvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-18907.
Повний текст джерелаNRPF-3, Rymdstyrelsen, 241/15
Huang, Peng Rui, and 黃鵬瑞. "Study of ionospheric scintillation by the rytov approximation." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/06363324583318211719.
Повний текст джерелаZhang, Ming Sheng, and 張明生. "Simulations of ionospheric scintillation with the phase screen method." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/52631548766461271681.
Повний текст джерелаChiu, Ji-Heng, and 丘濟恆. "GPS Ionospheric Amplitude Scintillation Detection Using Support Vector Machine." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/224427.
Повний текст джерела國立臺灣海洋大學
通訊與導航工程學系
106
In this thesis, the problem for detecting ionospheric amplitude scintillation is investigated. We solve this problem using a machine-learning algorithm called Support Vector Machine(SVM). Four kinds of training data are tested, including moving average of ionospheric amplitude scintillation index, moving maximum of ionospheric amplitude scintillation index, power spectrum density of moving average of ionospheric amplitude scintillation index transforming with short-time Fourier transform, power spectrum density of signal intensity transforming with short-time Fourier transform. With the above training data in hand, it is shown in this thesis that the proposed method can effectively detect the ionospheric scintillation in the GPS signals. Comparing with conventional mathematical model, support vector machine is more efficient to identify the ionospheric scintillation feature. When applying the kernel trick appropriately, support vector machine has good results in most classification tasks for both linear and non-linear data.
LIN, WEI-XIANG, and 林煒翔. "MITIGATING THE EFFECTS OF IONOSPHERIC SCINTILLATION ON GPS CARRIER TRACKING LOOP." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/24930146046796592957.
Повний текст джерела國立雲林科技大學
電機工程系
103
Global Positioning System (GPS) about Navigation section of daily life, provide assistance to people. Global Navigation Satellite System can be divided into receiver, the Front-end structure of antenna, this paper focuses on carrier phase tracking in the receiver, when the whole phase-locked loop design was bad, or can't to catch up with phase changes, carrier tracking loss of lock would result the required navigation message cannot be obtained. This article will introduce study of ionospheric scintillation effects. A library of empirical equatorial phase and amplitude scintillation phenomena has been compiled for use in the testbed. The proposed PLL are connected to the testbed by BP and RBF neural network and FUZZY adaptive PID control method, simulated using MATLAB software to get error changes of the phase locked loop discriminator output by use of different Scintillation severity and noise bandwidth, analysis statistical the phase standard deviation and error cumulative amount of the phase. Finally, through a comparison advantage of three data modulation PID method and the traditional phase-locked loop, Phase-locked to illustrate the impact of different scintillation index and noise bandwidth.
wang, Teng-Yu, and 王騰嶽. "The investigation of ionospheric scintillation by using ROCAT-1 and GPS data." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/49570829435488657193.
Повний текст джерела國立中央大學
太空科學研究所
93
According the data taller from GPS (Global Positioning System) system around Tainan. We calculate the total electron content (TEC) from pseudo range of the GPS signals caused by the delay of ionosphere. According to the carrier to noise (C/N) ratio of the GPS signal, we could estimate the S4 index which represents the degree of the fluctuation of the plasma irregularity in the path of GPS signal with the help of S4 index and the information of the orbit of GPS satellites, we can position the location of the plasma irregularity in the course of the satellite. Once the plasma irregularities are positioned. The spatial distribution of the ionospheric scintillation can thus be realized. Therefore, if we can develop a method to estimate the drift speed and direction of the plasma irregularity from GPS signals, it will be possible to forecast the occurrence of the ionospheric scintillation which will be beneficial to the improvement of the quality of the satellite communication.
Knight, Mark Frederick. "Ionospheric scintillation effects on global positioning system receivers / by Mark Frederick Knight." Thesis, 2000. http://hdl.handle.net/2440/19809.
Повний текст джерелаxxix, 304 p. : ill., col. maps ; 30 cm.
Uses a widely accepted stochastic model of scintillation activity to investigate the effects of scintillations on GPS receivers and systems.
Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 2001?
Hsueh, Brian Chang Chi. "Simulation and Compensation of Ionospheric Phase Phase Scintillation Noise in Spotlight SAR Data." Thesis, 2009. http://hdl.handle.net/1807/18323.
Повний текст джерелаTsai, Her-Chan, and 蔡和展. "On the Relationship between Equatorial Electrojet and Ionospheric Scintillation measured by FORMOSAT-3/COSMIC." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/n5k36y.
Повний текст джерела國立中央大學
太空科學研究所
97
In the day time equatorial ionosphere, there has been often observed a strong eastward current which is called Equatorial Electro-Jet (EEJ). According to the Ampere’s law, the current can induce the magnetic variations in its surroundings. Therefore scientists use magnetic observatories to measure the changes of magnetic field caused by EEJ and study the morphology of Equatorial electrojet. This thesis used the magnetic observatories’ data of International Real-time Magnetic Observatory Network to study the variations of magnetic field caused by Equatorial electrojet. Then we compared the Equatorial electrojet with ionosphere scintillations (represented by S4 values) detected by the FORMOSAT-3 satellites. The main task of this thesis consists of two parts. The first part is to study the morphology of EEJ, while the second part deals with the comparisons between EEJ and ionospheric scintillations. The main purpose of this thesis is using 2007 data sets to study the relationship between EEJ and the magnetic field variations affected by the EEJ under the following conditions: during the days of equinox and solstice; during 10 quiet days near the spring equinox; quiet times during the spring season; and on the May 23 storm day. From analyses of the magnetic field variations affected by EEJ, we found that there existed a seasonal variation in the morphology of EEJ. The seasonal (2007 spring) average location of EEJ is during 9 to 14 LT and ranges from the magnetic latitude 2o N to 3.15o S, while the maximum induced ∆H was about 116 nT. From the statistical comparison between EEJ and scintillation we have the following results: on spring equinox day positive correlation was found between their intensities; 10 days’ and seasonal averages reveal that stronger scintillations occurred near the boundary of EEJ. Moreover, from the comparison of the observations on storm day and quiet days we have the following findings: on storm day the EEJ current has changed it’s direction from that of quiet day pattern; and the average S4 is generally increased in the storm time EEJ region. Both EEJ and ionosphere scintillation change coherently when they have magnitude variations.
Wu, Meng-Ying, and 吳孟穎. "Phase Scintillation of GPS Signals due to Ionospheric Irregularities in the Equatorial and Polar Regions." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/75e9yv.
Повний текст джерела國立臺灣大學
電信工程學研究所
104
Phase scintillations of GPS signals caused by ionospheric irregularities in the equatorial and polar regions are simulated and analyzed. The electron density irregularities in the ionosphere are modeled with different spectra, and realized with a Monte-Carlo technique. A parabolic wave equation (PWE) technique is then applied to compute the field distribution of GPS signals as they propagate through the ionosphere. The simulated phase scintillation in high-latitude regions is much more obvious than that in the equatorial region.
Yu-HsuanChen and 陳育暄. "Design and Implementation of Real-Time GNSS Software Receiver and its Applications in the Presence of Interference and Ionospheric Scintillation." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/73166070456940363045.
Повний текст джерела