Self-calibration of a multiple channel clearance sensor system, which in one embodiment includes at least one sensor for measuring at least one clearance parameter signal between a stationary object and a rotating object of a rotating machine. The sensor output is processed as a clearance parameter by an offset correction section configured to determine an offset error in the clearance parameter signal which is used by a level shifter. The level shifter is also switchably coupled to the clearance parameter signal wherein the output of the level shifter, which may be amplified and digitally converted, is processed by a signal level analyzer to determine a channel gain signal.