Satellite and receiver clock drifts are not taking into account in range-rate measurement theoritical evalutation.
According to [1], the most significant contributors to the range-rate measurement are the line-of-sight velocity and the receiver clock drift. Furthermore, the satellite clock drift must be also taking into account when modelling a range-rate measurement. However, these two time drifts are not used in the theoretical evaluation of the range-rate measurement. Their contributions must be added.
Suggestion: Orekit considers receiver and satellite clock offsets. However, range-rate measurement considers clock drifts. Therefore, adding two new ParameterDriver to consider the clock drifts (one in ObservableSatellite and another one in GroundStation) can be an easy solution to solve the problem.
[1]: Teunissen, P., & Montenbruck, O. (Eds.). (2017). Springer handbook of global navigation satellite systems, Eq. 14.82. Springer.