A method and apparatus to calibrate a
servo sensor disposed on a
tape head located adjacent a moving
magnetic tape is disclosed where that
magnetic tape includes at least one
servo edge comprising an interface between a first recorded
signal and a second recorded
signal, and where the
servo sensor provides a servo
signal, and where an independent
position sensor provides an IPS signal. The method first samples the servo signal and the IPS signal, calculates a
transfer function, and forms a first
calibration curve. The method then forms an average residual error value. If that average residual error exceeds the maximum allowable residual error, then the method applies an offset to the first
calibration curve to form a second
calibration curve. That second calibration curve is saved for subsequent use during, for example, read / write / erase operations.