A system for self-calibration of multiple channel clearance sensor system comprising: at least first and second sensors (40, 42) for measuring at least respective first and second clearance parameter signals (66, 68) between a stationary object and a rotating object; at least first and second offset correction sections (137, 143) configured to determine respective first and second offset errors (130, 132) in the respective first and second clearance parameter signals (66, 68); at least first and second level shifters (120, 124) coupled to the respective said first and second offset errors and switchably coupled to the respective said first and second clearance parameter signals (66, 68); at least first and second amplifiers (138, 140) to amplify the respective first and second level shifter outputs (134, 136); at least first and second analog to digital converters (146, 148) coupled to the respective first and second amplifier outputs (142, 144) to provide respective first and second digital outputs (150, 152); at least first and second signal level analyzers (154, 156) coupled to the respective first and second digital outputs (150, 152); characterized in that the system further comprises: a common reference signal provided to be switchably coupled (112, 114) to respective said first and second level shifters (120, 124); wherein the switchable coupling (112, 114) of the first and second level shifters (120, 124) and the common reference signal are operable to switch between: i) the common reference signal being input to the respective first and second level shifters (120, 124); and ii) the first and second clearance parameter signals (66, 68) being input to the respective first and second level shifters (120, 124); the system being adapted to be operable such that when the common reference signal is input to the respective first and second level shifters (120, 124), a discrepancy in voltage signals obtained from the first and second signal level analyzers (154, 156) respectively is measured, the gain of one or both of the first and second amptifiers (138, 140) is adjusted to match the measured discrepancy in the respective voltage signals. at least first and second sensors (40, 42) for measuring at least respective first and second clearance parameter signals (66, 68) between a stationary object and a rotating object; at least first and second offset correction sections (137, 143) configured to determine respective first and second offset errors (130, 132) in the respective first and second clearance parameter signals (66, 68); at least first and second level shifters (120, 124) coupled to the respective said first and second offset errors and switchably coupled to the respective said first and second clearance parameter signals (66, 68); at least first and second amplifiers (138, 140) to amplify the respective first and second level shifter outputs (134, 136); at least first and second analog to digital converters (146, 148) coupled to the respective first and second amplifier outputs (142, 144) to provide respective first and second digital outputs (150, 152); at least first and second signal level analyzers (154, 156) coupled to the respective first and second digital outputs (150, 152); characterized in that the system further comprises: a common reference signal provided to be switchably coupled (112, 114) to respective said first and second level shifters (120, 124); wherein the switchable coupling (112, 114) of the first and second level shifters (120, 124) and the common reference signal are operable to switch between: i) the common reference signal being input to the respective first and second level shifters (120, 124); and ii) the first and second clearance parameter signals (66, 68) being input to the respective first and second level shifters (120, 124); the system being adapted to be operable such that when the common reference signal is input to the respective first and second level shifters (120, 124), a discrepancy in voltage signals obtained from the first and second signal level analyzers (154, 156) respectively is measured, the gain of one or both of the first and second amptifiers (138, 140) is adjusted to match the measured discrepancy in the respective voltage signals. a common reference signal provided to be switchably coupled (112, 114) to respective said first and second level shifters (120, 124); wherein the switchable coupling (112, 114) of the first and second level shifters (120, 124) and the common reference signal are operable to switch between: i) the common reference signal being input to the respective first and second level shifters (120, 124); and ii) the first and second clearance parameter signals (66, 68) being input to the respective first and second level shifters (120, 124); the system being adapted to be operable such that when the common reference signal is input to the respective first and second level shifters (120, 124), a discrepancy in voltage signals obtained from the first and second signal level analyzers (154, 156) respectively is measured, the gain of one or both of the first and second amptifiers (138, 140) is adjusted to match the measured discrepancy in the respective voltage signals.