Assume I have the coordinates of satellite xs (t) and ground station xg (t) in the International Terrestrial Reference Frame (ITRF). Also, the attitude of satellites in the form of quaternions is available, which represents the change of frame between the satellite reference frame and the Earth-centered inertial (ECI) reference system (J2000)

I am looking for the considerations and equations essential for accurately calculating the instantaneous range, R (t) = xs (t) – xg (t), while accounting for the varying attitude of the satellite and how changes in the satellite's attitude may affect the accuracy of the instantaneous range.

I welcome expertise from researchers familiar with satellite positioning (ITRF and ECI coordinate systems), quaternion-based attitude representations, and the details of calculating instantaneous range considering the satellite's attitude. Any insights, references, or guidance on relevant literature would be greatly appreciated.