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@InProceedings{EspejoCosMorPauMon:2019:EqLoIo,
               author = "Espejo, Teddy M. Surco and Costa, Emanuel and Moraes, Alison de 
                         Oliveira and Paula, Eurico Rodrigues de and Monico, Jo{\~a}o 
                         Francisco Galera",
          affiliation = "{Pontif{\'{\i}}cia Universidade Cat{\'o}lica do Rio de Janeiro 
                         (PUC-Rio)} and {Pontif{\'{\i}}cia Universidade Cat{\'o}lica do 
                         Rio de Janeiro (PUC-Rio)} and {Instituto de Aeron{\'a}utica e 
                         Espa{\c{c}}o (IAE)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)} and {Universidade Estadual Paulista (UNESP)}",
                title = "Equatorial and Low-Latitude Ionospheric Effects on GPS Signals in 
                         Space and on Ground Based Augmentation System Operations",
                 year = "2019",
         organization = "AGU Fall Meeting",
             abstract = "Ground Based Augmentation Systems (GBAS) have been developed to 
                         meet the safety requirements of air navigation,using differential 
                         corrections to provide higher accuracy during aircraft approach 
                         and landing operations. However, ionospheric delays and 
                         scintillation cause positioning errors that degrade the accuracy, 
                         performance and availability of Air Navigation Systems that 
                         operate using the Global Positioning System (GPS), particularly in 
                         the equatorial and low-latitude regions. The propagation and 
                         degradation of GPS signals in space due to ionospheric effects are 
                         the focus of this work, which describes a simulation model of the 
                         GPS observables. For each active communication channel between a 
                         satellite and a reference ground receiver or aircraft,the 
                         pseudorange PR, carrier phase \Φ and received power C for 
                         the GPS L1 signals were simulated, considering the clock errors, 
                         ionospheric and tropospheric delays, multipath, amplitude and 
                         phase scintillation, random errors, free-space loss and antenna 
                         gains. Ionospheric delays were estimated through statistical 
                         distributions of residuals between the vertical Total Electron 
                         Content (vTEC) at associated 400-km ionospheric pierce points 
                         (IPP)estimated from the data recorded by the dual-frequency GPS 
                         receivers of the RBMC/IBGE network,and the relative vTEC estimated 
                         by the latest version of the International Reference Ionosphere 
                         (IRI). Samples of amplitude and phase scintillation were generated 
                         according to \α \μ probability distributions, 
                         conforming to data collected by receivers of the CIGALA/CALIBRA 
                         network, located in different geomagnetic latitudes. Next, the 
                         results from the above model were processed by algorithms to 
                         detect possible degradations in the GPS signals, isolate failures, 
                         smooth and correct acceptable ones, and transmit correction 
                         messages to aircrafts through the VDB (VHF Data Broadcast).GBAS 
                         availability was also evaluated by computing the Vertical 
                         Protection Levels (VPL). This contribution will present and 
                         discuss statistical analyses of position errors resulting from the 
                         simulation of GPS observables and GBAS operations for different 
                         combinations of geophysical parameters(solar and geomagnetic 
                         activity, geomagnetic latitude, local time and season) and 
                         scenarios.",
  conference-location = "San Francisco, CA",
      conference-year = "09-13 dec.",
             language = "en",
           targetfile = "espejo_equatorial.pdf",
        urlaccessdate = "29 mar. 2024"
}


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