-This can be used to set the ionosphere-free linearcombination of two Observable-specific Signal Biases (OSBs; -those of the reference signals) to zero in order to calculate all other OSBs. +In order to ensure the interoperability between corrections of different ACs (which may use different signals for clock estimation) +and to be consistent with respect to the IGS convention (clock corrections are based on the ionosphere-free linear combination +of the respective reference signals) the individual satellite clocks and code biases are taken together. +This means, the individual AC clocks are reduced epoch by epoch by the individual ionosphere-free linear combination of individual AC code biases, +delivered for the reference signals, before its combination: +
++Henc, the ionosphere-free linear combination of code biases for the IGS reference signals is determined +from the supplied code biases and subtracted from the clocks before combination. +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 AC may contain contributions from other biases, also phase biases. +
++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.