Hi all,
in a LEO OD context, when both GPS and Galileo measurements are present in the RINEX file, is it possible to estimate a receiver clock offset/drift related to GPS constellation and a receiver clock offset/drift related to Galileo constellation?
No, it is not possible. The offset is in fact expressed with respect to an hypothetical perfect and unique time scale. So there are no provisions for the navigation time scales themselves.
What is possible, though, is to estimate the emitters clocks too (well at least one should be set as a reference end not estimated, or some composite clock algorithm should be used).