Abstract
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.
Highlights
GNSS (Global Navigation Satellite Systems) led to fast technological improvement in positioning activities
We present some results from the improved virtual reference station (VRS)-UNESP version, which enables GLONASS virtual data generation
Considering PBJP and SPDR, the greater variability of results from October data was clear, even though PBJP presented more similar mean squared errors (MSE) values considering results from real and virtual observables
Summary
GNSS (Global Navigation Satellite Systems) led to fast technological improvement in positioning activities. Nowadays (2019), GLONASS (GLObal NAvigation Satellite System) and GPS (Global Positioning System) are the systems available with full constellations. In the analysis carried out in this paper, three different approaches were considered: the systems (GPS and GPS/GLONASS data were used); the ionospheric activity (seasonal and regional variations were considered); and the type of data (real and virtual data were assessed). The main systems, GPS and GLONASS, started to be developed in the seventies and, nowadays, are the systems with full global coverage. The system reached full constellation in 1995 and, since has been modernized with new satellites (Hofmann-Wellenhof, Lichtenegger and Wasle 2008; Langley, Teunissen and Montenbruck 2017). Nowadays (2019), GPS III/Block IIIF is under development, where a fourth civil signal will be available (L1C) (GPS 2018)
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