Measured speed versus true speed

The theoretical predictions, derived from the Lorentz and the Tangherlini transformations, for the one-way speed of any physical entity are confronted with the corresponding expressions for the one-way measured speed obtained from a gedanken experiment. The experiment demonstrates that, for an inertial frame $K'$ in motion relative to an inertial frame $K$ where the one-way speed of light is isotropic, even the special theory of relativity renders the one-way speed of light as function of the velocity of $K'$ in agreement with the Tangherlini transformations. However, the two-way speed of light remains constant for all inertial frames, in agreement with the two-way experimental techniques. This implies that there must exist \emph{one and only one} inertial frame where the one-way speed of light is isotropic. These investigations also show how we can determine, with certain restrictions, the true speed of a physical entity and of the true speed of $K'$ relative to $K$.