Abstract: The present invention comprises devices and methods for recovering a block of data. In a preferred embodiment, a block erroneously read due to improper read head nonlinearity compensation is recovered with only one re-read attempt. For the first portion of the block read, the rate of nonlinearity compensation adaptation is up-shifted to a rate more than twice the nominal rate. Substantially off of the remainder of the block is then read with a down-shifted compensation. Preparatory steps are also provided for simple ranging, iterative ranging, and otherwise deriving a nonlinearity compensation value from stored data and software implemented by a controller.

Abstract: A disc drive data recovery system for recovering data from a magnetic disc having asperities is disclosed. The data recovery system includes a magnetoresistive head for reading magnetically encoded data from the magnetic disc and providing in response a signal indicative of the magnetically encoded data. Contact between the magnetoresistive head and an asperity corrupts the signal such that the signal contains thermal asperity noise. The data recovery system includes an asperity recovery filter coupled to the magnetoresistive head for receiving the signal from the magnetoresistive head and reducing the thermal asperity noise in the signal.