-The combination is done system-wise for the following reference signals as specified in the IGS RTWG: +The combination is done system-wise for the following reference signals as specified in the IGS Real-Time Committee:
+When the individual satellite clocks and code biases are used together, the effective Observable-Specific Biases (OSBs) are recovered. +With it, the interoperability between corrections of different RTACs, which may use different signals for clock estimation, is ensured. +Hence, the individual RTAC satellite clocks are reduced epoch by epoch by the individual ionosphere-free linear combination +of individual RTAC satellite code biases, delivered for the reference signals, before its combination. +With it, the combined satellite clocks are consistent to IGS clocks, which means ionosphere-free clocks +based on the defined reference signals - despite the fact, that the delivered code biases of an RTAC may contain contributions +from other biases, also phase biases (Banville et al. 2020).
@@ -4823,10 +4826,20 @@
-This can be used to set the ionosphere-free linear combination of two Observable-specific Signal Biases (OSBs; -those of the reference signals, because they are part of the clocks per definition) to zero, in order to calculate all other OSBs. -For this, we use currently the satellite biases which are computed by the Institute of Geodesy and Geophysics (IGG) -of the Chinese Academy of Sciences (CAS) and send them out as SSR code biases together with the combined clocks. -These SINEX Bias files are archived at the CDDIS: +This convention allows the ionosphere-free linear combination of the two OSBs of the reference signals to be set to zero. +All other OSBs can then be expressed in terms of Differential Code Biases. For this, +the PCO-corrected satellite DCB product (Wang et al. 2025) of the Chinese Academy of Sciences (CAS) is used and send out +as SSR code bias together with the combined clocks. These SINEX Bias files are archived at CDDIS: https://cddis.nasa.gov/archive/gnss/products/bias/ +
++References: +
++Banville S., Geng J., Loyer S., Schaer S., Springer T., Strasser S. (2020) On the interoperability of IGS products for precise point positioning with ambiguity resolution. Journal of Geodesy. 94, 10 (2020). +https://doi.org/10.1007/s00190-019-01335-w +
++Wang N., Li Y., Li Z., Liu A., Liu B. (2025) Determination of multi-GNSS differential code biases with satellite antenna phase center corrections. GPS Solutions 30, 22 (2026). +https://doi.org/10.1007/s10291-025-01983-w