  Geometric optics approximation is sufficient to describe the effects in the
near-Earth environment. In this framework Faraday rotation is purely a
reference frame (gauge) effect. However, it cannot be simply dismissed.
Establishing local reference frame with respect to some distant stars leads to
the Faraday phase error between the ground station and the spacecraft of the
order of $10^{-10}$ in the leading post-Newtonian expansion of the Earth's
gravitational field. While the Wigner phase of special relativity is of the
order $10^{-4}$--$10^{-5}$. Both types of errors can be simultaneously
mitigated by simple encoding procedures. We also present briefly the covariant
formulation of geometric optic correction up to the subleading order
approximation, which is necessary for the propagation of electromagnetic/
gravitational waves of large but finite frequencies. We use this formalism to
obtain a closed form of the polarization dependent correction of the light ray
trajectory in the leading order in a weak spherically symmetric gravitational
field.
