The present invention is directed to a method and apparatus for dynamic placement of an integration window in a disk drive having a disk surface with spiral servo information written thereon. A read head is provided for reading the spiral servo information and generating a read signal envelope. A repetitive spiral position error, associated with one spiral of the spiral servo information, is measured. Placement of an integration window is dynamically adjusted based upon the measured repetitive spiral position error, so that a read signal envelope read by the read head appears more towards the center of the integration window than if the placement of the integration window was not dynamically adjusted. By adjusting the placement of the integration window, dynamic range is increased without increasing the size of the integration window.

 
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> Head for perpendicular recording with reduced erasure

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