GNSS position time series contain signals induced by earth deformation, but also by systematic errors, at different time scales, from sub-daily tidal deformation to inter-annual surface-loading deformation and secular tectonic plate rotation. This software allows users to visualize GNSS position time series, but also any other series, and interactively remove outliers and discontinuities, fit models and save the results. A comprehensive list of features is included to help the user extracting relevant information from the series, including spectral analysis with the Lomb–Scargle periodogram and wavelet transform, signal filtering with the Kalman filter and the Vondrák smoother, and estimation of the time-correlated stochastic noise of the residuals. The software can be run on a local machine if all the package dependencies are satisfied or remotely via a public web server with no requirement other than having an internet connection.
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Sylvain Loyer provided invaluable help in implementing the Vondrák smoother. Comments from Valérie Ballu, Paul Rebischung, Pascal Gegout and Giorgi Khazaradze were very useful to improve the software. I am also deeply grateful to many R developers providing code solutions online, but mainly to Dean Attali and Stefan Gelissen. This research is supported by RESIF/RENAG. RESIF is supported by a public grant provided by the French National Research Agency (ANR) as part of the “Investissements d’Avenir” program, with reference ANR-11-EQPX-0040, and the French Ministry of Environment, Energy and Sea.
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The GPS Tool Box is a column dedicated to highlighting algorithms and source code utilized by GPS engineers and scientists. If you have an interesting program or software package you would like to share with our readers, please pass it along; e-mail it to us at firstname.lastname@example.org. To comment on any of the source code discussed here, or to download source code, visit our website at http://www.ngs.noaa.gov/gps-toolbox. This column is edited by Stephen Hilla, National Geodetic Survey, NOAA, Silver Spring, Maryland, and Mike Craymer, Geodetic Survey Division, Natural Resources Canada, Ottawa, Ontario, Canada.
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Santamaría-Gómez, A. SARI: interactive GNSS position time series analysis software. GPS Solut 23, 52 (2019) doi:10.1007/s10291-019-0846-y
- GNSS time series
- Model fitting
- Discontinuity detection
- Signal processing