i have found in docs:
The minimal messages, required for RTK are 1002 and 1006. They contain GPS L1 observations(extended data) and base antenna coordinates(extended data). If you wish to add GLONASS L1 observations, use 1010 as well.
whats about with:
Type 1019, GPS ephemeris.
Type 1020, GLONASS ephemeris.
are they need for realtime work?
i have read also that sbas is not necessary for realtime rtk.