| 摘要 |
A method and apparatus for performing track follow and seeking at quarter track positions that uses a non-conventional ordering of the servo fields at the quarter track positions, wherein C-A or D-B is used to track follow at-¼ track positions and A-D or B-C is used to track follow at +¼ track positions, for even and odd tracks, respectively. A position error signal is derived from relative amplitudes of the servo bursts and the read/write head is positioned over the quarter track position in accordance with the position error signal. The servo bursts are read in a time-displaced manner and the position error signal is determined from the relative amplitudes of the servo bursts. A servo controller is provided that includes a digital control/timing circuit that controls timing of events within the servo controller and generates an offset signal, a servo demodulator that receives a read back signal from the read/write head and determines a difference signal, a summing node that receives the difference signal and the offset signal, and a programmable gain stage that generates a position error signal based on an output of the summing node.
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