Improved PPP performance in regional networks

Abstract

It has been demonstrated that precise point positioning (PPP) is a powerful tool in geodetic and geodynamic applications. As is known, it provides solutions in the reference system of the satellite orbits. We focuses on the strategy to transform PPP solutions into the International Terrestrial Reference System (ITRS) by applying a set of local Helmert transformation parameters obtained from a regional network rather than using global parameters. In order to carry out this test, a regional network composed of 14 stations was analyzed using GIPSY-OASIS II software, over a period of 6 years. Two solutions differently aligned to the ITRS were compared in terms of accuracy, scattering, frequency content and local movements. One solution is aligned to IGb08 through the X-files provided by JPL, while the other is aligned to the European reference frame densification of IGb08 using customized regional X-files. Therefore, both are updated realizations of the ITRS. The test shows that a regional, instead of a global, alignment to the ITRS can significantly improve the repeatability of the solutions. A small improvement can also be found in terms of agreement with the regional densification of IGb08. The analysis of the signal content in the differently aligned time series allowed some differences to be found, in terms of both frequency and magnitude. These differences are mainly due to an evident common signal that is defined for the whole area and which is removed when using regional alignment. Finally, residual scattering was calculated after removing the modeled signals from each time series, which results in a scatter being significantly smaller for the regional solution than for the global solution. In order to obtain these results, the choice of the reference stations is a major question and therefore discussed in detail.

Performance Assessment of PPP Surveys with Open Source Software Using the GNSS GPS–GLONASS–Galileo Constellations

“…For this reason, an outlier rejection strategy in position domain is necessary too. The outlier rejection strategy, adopted to improve the stability of the positioning, consists in discarding the daily solutions outsides the 6σ interval centered at the final solution [50,51]. The X coordinates of the daily solutions for GPS-only case, after the rejection of the anomalous daily solutions, are shown in Figure 8b.…”

15 Years of the Italian GNSS Geodetic Reference Frame (RDN): Preliminary Analysis and Considerations

“…Moreover, the PPP approach does not require the contemporary acquisition from more than one receiver, making more flexible the data processing of large networks. GIPSYX follows an undifferenced approach, which allows elaborating each station independently from the others, allowing the reprocessing of a single station in case of mistakes [7,14,15]. The other great advantage of the PPP is related to the direct alignment of the coordinates onto a global reference frame and the independence from any kind of geodetic infrastructure on the ground [16].…”

GNSS Cors Network of the University of Palermo: Design and First Analysis of Data

“…10 show the geocentric components (X, Y and Z) of all GNSS CORS coordinates corresponding to the GPS epochs (MJD). Preliminary, the outliers have been removed from the time-series and the evolution of the scattered behaviour has been plotted within the range ±3σ, as reported in literature (Barbarella et al, 2018;Gandolfi et al, 2016). In Table 3 also the average errors related to the X, Y, Z components of the CORS coordinates have been reported.…”