Patent ID: 7907482

Claim:
A method for correction of track related errors of an optical information carrier ( 14 ) during recording by a recorder, comprising an optical pick-up unit ( 30 ) controlled by a servo system ( 34 ) arranged to follow tracks prerecorded in said carrier, the method characterized in: retrieving an amplitude and phase of a motor disturbance at an i:th harmonic of rotation frequency, where i=1. . . N, pertaining to periodic disturbances associated with the rotational speed of a drive mechanism or any harmonics thereof relating to the recorder, from a memory of the recorder; and adding said amplitude and phase of a motor disturbance at an i:th harmonic of rotation frequency, to a repetitive control/learning feedforward control circuit ( 88 ) of said servo system ( 34 ) to correct for said periodic disturbances during recording.