Systems and methods are disclosed that provide highly accurate and controllable measurements of rock formation properties in a wellbore. The systems and methods utilize a prescribed input signal to mechanically perturb a drill string in contact with a rock formation in order to elicit a mechanical response. Based on the input signal and the mechanical response, a transfer function is computed and analyzed, wherein the analysis uses estimates of the drill string resonances to identify rock formation resonances, which are used, in turn, to determine the rock formation properties.