Method and system for providing servo signals to a magnetic head

Abstract

A method and system for developing continuous position control signals for continuously repositioning a data head relative to an addressed data track on a rotating magnetic disk. The method includes the steps of formatting the disk with a unique servo pattern to provide servo signals having servo frequencies F1 and F2, which correspond to spectral nulls in the frequency spectrum of the encoded data stored on the disks. The method further establishes addressable data track locations related to the servo pattern which have a nominal width corresponding to the width of one servo band of the pattern. After positioning the data head to a data track the method involves 'side' reading with the data head the servo pattern that is adjacent both sides of the data track to develop the positional control signals as data encoded with spectral nulls at F1 and F2 is transferred to and from the disk. The system comprises a magnetic disk that has a prerecorded servo pattern to provide two position control signals at F1 and F2 which correspond to spectral nulls in the frequency spectrum of the encoded data that is stored on the disk and a plurality of addressable data tracks, the location of each being determined by the servo pattern. The system further includes an actuator for positioning a data head to a selected data track and circuit connected to the data head to develop position error signals from the F1 and F2 signals generated by the data head, 'side' reading the pre- recorded servo pattern.