Restoration of hard disk drive readback signal in the presence of thermal modulation

摘要

A magnetoresistive (MR) head of a hard disk drive provides a readback signal from a data storage disk. The readback signal is high pass filtered, amplified, sampled and digitized to obtain a digital readback signal. A thermal component of the digital readback signal is removed from the digital readback signal by an efficient nonlinear process in which an envelope of the digital readback signal is estimated to obtain upper and lower envelope sequences. The upper and lower envelope sequences are averaged to derive the estimated thermal component to be subtracted from the digital readback signal.