METHOD AND APPARATUS FOR ELIMINATING APPARENT OFFSET IN THE SERVO CODE IN A MAGNETIC DISC DRIVE

摘要

AbstractThis method and apparatus for eliminating apparentoffset in the servo code adjacent to a guard band on amagnetic memory disc utilizes at least two phases of servocode per magnetic cell for seeking and track centering, ortrack following, operations and two phases of guard bandcode per magnetic cell. The two phases of guard band codeare each either in phase or similarly out of phase with therespective phases of the servo code in individual magneticcells.Phase locking on a selected phase of guard bandcode is achieved by providing a synchronizing code in theguard band using an irregular pattern of guard band code,providing a timing signal count representing a cell count,for example, decoding the synchronizing code to provide anend of code signal and utilizing the end of code signal anda predetermined cell count signal to achieve phase lockingon the correct phase of the guard band code.