A method comprises activating an interval timer to expire in a calibration time interval and, in response to the timer expiring, performing an impedance analysis of an electronic network. The impedance analysis can use time-domain reflectometry. Based on the analysis, the method can calibrate a variable impedance device to have a first impedance and re-activate the timer. The method can perform a second impedance analysis based on calibrating the variable impedance device. The method can include determining a drift rate and modifying the calibration time interval. The variable impedance device can comprise a phase-change material (PCM), and the time interval can correspond to a retention time of the PCM and/or a dynamic drift rate. A system comprising a segment of an electronic network, a timer, a variable impedance device, and an impedance tuning system can embody operations of the method.