A tape-drive condensation sensor includes a probe with first and second spaced-apart electrodes that define a passage for air flow within a pneumatic conduit. The docking station may serve as a home base for storage of a marking device, for charging the battery of a marking device, for transferring data to and from a marking device, and for securing a marking device against unauthorized use andor theft. Using the recorded read-back signals, coefficients for an empirical curve-fit equation are calculated.