Offset compensation in local-probe data storage devices

摘要

Methods and apparatus for compensating offsets in a read signal generated by a sensor associated with a probe of a local-probe data storage device during read-scanning by the probe of bit-positions on a storage surface. An apparatus comprises a generator for generating an offset compensation signal, and a subtraction stage for producing an output signal dependent on the difference between the offset compensation signal and the sensor read signal at each bit-position. In some embodiments, an offset signal generator generates an offset compensation signal dependent upon a predetermined measurement of the sensor read signal. In another aspect the offset signal generator low-pass filters the sensor read signal during read scanning to generate the offset compensation signal. Particular embodiments also include a secondary offset compensation stage for applying additional offset compensation techniques to the output signal from the subtraction stage.