US 7,466,766 B2 · Processing servo data having DC level shifts

Abstract

A read channel component of a magnetic recording system employs equalization of a signal received from the magnetic recording channel, the equalization being modified depending upon the presence or absence of DC shifts in the signal. Equalization corrects for DC shifts, if present, prior to detection and decoding of servo data, such as servo address mark (SAM) and Gray code data. In a first implementation, a DC shift detector detects the presence or absence of DC shifts and modifies equalization in a predetermined manner. In a second implementation, filtering is applied to the signal to enhance equalization in the presence of DC shift, and both filtered and unfiltered signals employed for detection of the servo data.

Claims24

Dependent claims

An apparatus for detecting data in a signal read from a channel, the apparatus comprising:

an equalizer configured to apply equalization to the signal to account for a DC shift in the signal;
and
a detector adapted to detect the data based on either the presence or absence of the DC shift in the signal;
and further comprising:
a DC shift detector adapted to detect the presence or absence of the DC shift in the signal and to generate a corresponding DC shift detect signal;
wherein the equalizer, in response to the DC shift detect signal, modifies the equalization to Nyquist equalization when the DC shift detect signal indicates the presence of the DC shift in the signal.

3 more elements

Dependencies are inferred from the claim text.

Processing servo data having DC level shifts

Life of this patent

Processing servo data having DC level shifts

Life of this patent

Abstract

Claims24