Abstract: Correction for harmonic disturbances on rotating storage media in a phase-locked loop. The effects of harmonic disturbances in a phase-locked loop are reduced by employing harmonic correction. Harmonic correction may be present in the loop at all times, or may be switched in once the loop has achieved phase lock. Disturbance within the loop bandwidth is corrected using additional integrating pole or a bump (resonant) filter. Disturbance outside the loop bandwidth is corrected using low pass or a notch (anti-resonant) filter. Alternately, a canceling signal may be generated and added as a feedforward signal. A repetitive control scheme uses a filtered version of the residual errors on previous media rotations as a feedforward signal to cancel harmonic effects.

Abstract: Correction for harmonic disturbances on rotating storage media in a phase-locked loop. The effects of harmonic disturbances in a phase-locked loop are reduced by employing harmonic correction. Harmonic correction may be present in the loop at all times, or may be switched in once the loop has achieved phase lock. Disturbance within the loop bandwidth is corrected using additional integrating pole or a bump (resonant) filter. Disturbance outside the loop bandwidth is corrected using low pass or a notch (anti-resonant) filter. Alternately, a canceling signal may be generated and added as a feedforward signal. A repetitive control scheme uses a filtered version of the residual errors on previous media rotations as a feedforward signal to cancel harmonic effects.

Abstract: Correction for harmonic disturbances on rotating storage media in a phase-locked loop. The effects of harmonic disturbances in a phase-locked loop are reduced by employing harmonic correction. Harmonic correction may be present in the loop at all times, or may be switched in once the loop has achieved phase lock. Disturbance within the loop bandwidth is corrected using additional integrating pole or a bump (resonant) filter. Disturbance outside the loop bandwidth is corrected using low pass or a notch (anti-resonant) filter. Alternately, a canceling signal may be generated and added as a feedforward signal. A repetitive control scheme uses a filtered version of the residual errors on previous media rotations as a feedforward signal to cancel harmonic effects.

Abstract: An optical read/write drive such as a DVD+RW drive writes a block of new data to a read/write medium by locating an edit bit in the block of data that has already been written to the medium, and writing the block of new data to the medium, beginning or ending at the edit bit. The edit bit may be chosen to avoid errors arising from polarity conflicts between data already written to the disc and the new data. The edit bit could be, for example, a differing transition bit in a sync codeword of a modulation-encoded block.

Abstract: An optical read/write drive such as a DVD+RW drive writes a block of new data to a read/write medium by locating an edit bit in the block of data that has already been written to the medium, and writing the block of new data to the medium, beginning or ending at the edit bit. The edit bit may be chosen to avoid errors arising from polarity conflicts between data already written to the disc and the new data. The edit bit could be, for example, a differing transition bit in a sync codeword of a modulation-encoded block.

Abstract: A read/write drive such as a DVD+RW drive performs interleaved read and write operations on a recordable medium without relying on long seeks. During a first mode of operation, the read/write drive writes a pattern of data units (e.g., blocks) separated by gaps. Each gap spans the length of at least one data unit. During a second mode of operation, read and write operations are interleaved. At least some of the recorded data units in the pattern are read during the second mode, and new data units are written to gaps within short seeks of data units read during the second mode.

Abstract: An optical read/write drive such as a DVD+RW drive includes a write clock generator that allows new data to be written to an optical disc at a constant linear density while the drive is operating in a constant angular velocity mode. The write clock generator generates a zone write clock that is supplied to a laser driver during a write operation. The write clock generator can adjust the frequency of the zoned write clock to correspond to different zones of the optical disc.