Patent ID: 8615539
Filing Date: 2013-12-24
Classification: G11B

Abstract:
1. An apparatus for controlling a plurality of coefficients of a filter in a read channel of a magnetic media read apparatus that reads data from magnetic media, comprising: the filter having an input for receiving the data detected from the magnetic media, said filter having an output for outputting filtered data for equalization of the data in the read channel, said filter using said plurality of coefficients for generating the filtered data; a unit including a detector connected to receive an output of said filter, said unit being connected in a feedback loop, said filter being outside said feedback loop; a control connected to said filter to detect drift in said coefficients, said control being operable to determine said drift by estimating a gradient of an impulse response of each of said filter coefficients, said control imposing a leakage based on said detected drift on said filter coefficients to cause a response of the filter to return to a desired response; said filter having an LMS function using information from the detector about ideal sample values, the filter coefficients being updated according to the formula: where d is the leak down gain, C said drift being calculated according to the formula