Synchronous detection of concurrent servo bursts for fine head position

Abstract

Synchronous detection of fine position servo burst information with a data transducer having an electrical width not less than about two-thirds a width of a data track within a partial response maximum likelihood (PRML) data channel is disclosed. The servo burst information is recorded on a storage medium as a pair or series of fractional-track-width sinewave concurrent burst patterns and includes an on-track phase generating a position error signal which varies linearly with head displacement about track centerline and at least one off-track phase generating a position error signal which varies linearly with head displacement about a position related to track boundary. The method includes steps of reading the on-track phase and the off-track phase with a head to provide an analog signal stream, amplifying and low pass filtering the signal stream to normalize gain of the signal stream, synchronously quantizing the signal stream to provide synchronous digital burst samples, multiplying the synchronous digital burst samples during servo sampling intervals by a normalization factor generated by a correlation signal generator to provide normalized samples, integrating normalized samples originating during the on-track phase to provide an on-track position error signal, and integrating normalized samples originating during the off-track phase to provide an off-track position error signal. Circuitry implementing the method including a discrete matched filter is also disclosed.