We use a Sliding Window approach for the Real-Time processing, collecting all rinex data available within the most current two-hour period and performing a network solution using the PAGES [Schenewerk et al., 2000] processing software. Late arriving data triggers a re-run of the applicable time-window so that, at any given time, the solutions available represent the best possible estimates [Brooks et al., 2005].
PAGES uses all available data to set integers and estimate neutral atmosphere corrections while generating site coordinates for the sites of interest. The reference sites, KOK1, KOKB and MKEA, are constrained to their ITRF2000 coordinates. A piece-wise, linear neutral atmosphere (tropo) correction for each sites is estimated every hour. The 30 second, ionosphere free phase combination is used as the observable. The NGS antenna phase calibration patterns are applied [Mader and MacKay, 1996]. The IGS ultra-rapid orbits are used and held fixed. The IERS standard solid Earth tide [McCarthy, 2003] and Schwiderski ocean tide loading corrections are applied [Cartwright and Taylor, 1971; Cartwright and Edden, 1973].
Brooks, B. A., J. Foster, A. Miklius, and M. Schenewerk (2005), Extended GPS Network and Near Real-Time processing, Mauna Loa Volcano, Hawaii, Eos Trans. AGU, 86, Fall Meet. Suppl.
Cartwright, D. E., and A. C. Edden (1973), Corrected tables of tidal harmonics, Geophys. J. R. Astron. Soc., 33, 253-264.
Cartwright, D. E., and R. J. Taylor (1971), New computation in the tide-generating potential, Geophys. J. R. Astron. Soc., 23, 45-74.
Mader, G., and J. R. MacKay (1996), Calibration of GPS antennas, Geoscience Laboratory, Office of Ocean and Earth Sciences, NOS, NOAA, Silver Spring, Maryland.
McCarthy, D., and G. Petit (Eds.) (2003), IERS Technical Note 32, IERS Conventions (2003).
Schenewerk, M., W. Dillinger, and S. Hilla (2000), Online documentation for the PAGES suite of processing software, http://www.ngs.noaa.gov/GRD/GPS/DOC/toc.html.