Self-servo writing using reference patterns with timing correction

Abstract

Methods for writing servo fields on a rotatable data storage disk using reference patterns on the data storage disk include generating a clock signal, reading a reference pattern signal from a surface of the disk, generating a phase error signal in response to a phase offset between the clock signal and the reference pattern signal, subtracting a timing control value from the phase error to provide an adjusted phase error, generating a frequency control signal in response to the adjusted phase error, and adjusting the frequency of the clock signal. The timing control value is generated in response to the phase error signal and the frequency control signal.