Abstract: Aspects of the disclosure provide an apparatus. The apparatus includes a pick-up unit, such as an optical pick-up unit, a wobble channel and a defect detector. The pick-up unit generates a push-pull signal corresponding to a wobbled track of a storage medium. The wobble channel includes circuits to receive the push-pull signal, obtain a wobble signal from the push-pull signal, and calculate a wobble amplitude metric based on the wobble signal. The defect detector compares the wobble amplitude metric to a threshold to detect wobble defects.

Abstract: Aspects of the disclosure provide a method for signal processing. The method includes receiving a tracking signal corresponding to a recording track on a storage medium. The tracking signal is frequency modulated with encoded symbols. Further, the method includes phase-locking an internal signal to the tracking signal to cause a frequency of the internal signal to be locked at a center frequency of the tracking signal, detecting a drift between the internal signal and the encoded symbols, and phase-shifting the internal signal to compensate for the drift.

Abstract: A system with a nonlinear element processes a replay signal with a scaling factor into a signal compensated for asymmetry. The replay signal may include data from an optical disk. The scaling factor may be estimated based on the compensated signal and a scaling factor gain. The replay signal and the compensated signal may be converted into digital signals and processed digitally. In one embodiment, the compensated signal may be calculated as approximately the scaling factor multiplied by a square of an amplitude of the replay signal added to the amplitude of the replay signal. In another embodiment, the compensated signal may be calculated as approximately the scaling factor multiplied by an absolute value of an amplitude of the replay signal added to the amplitude of the replay signal. A related method is also disclosed. Other embodiments are provided, and each of the embodiments described herein can be used alone or in combination with one another.

Abstract: In one embodiment the present invention includes a qualification circuit that controls a read channel in a data storage device. The qualification circuit includes a first circuit and a second circuit. The first circuit receives a first signal and generates a second signal based on a signal quality of the first signal. The second circuit receives the second signal, an envelope-derived error signal resulting from performing envelope derived error detection, and a decision-aided error signal resulting from performing decision aided error detection. The second circuit modifies the envelope-derived error signal and the decision aided error signal according to the second signal. The second circuit generates a control signal that controls the read channel according to the envelope-derived error signal and the decision-aided error signal having been modified.

Abstract: Aspects of the disclosure provide a signal processing circuit to reduce signal distortions due to optical aberrations. The signal processing circuit includes a circuit configured to receive an electrical signal corresponding to a light beam reflected by a storage medium and filter the electrical signal to reduce distortions due to, for example, birefringence aberration in the light beam, and an equalizer configured to equalize the filtered electrical signal. In an example, the circuit is a median filter.

Abstract: A decoding system includes a decoder, a first module and a second module. The decoder is configured to receive data read from an optical storage medium and perform a first decoding iteration and a second decoding iteration to decode the data. The first decoding iteration includes generating a resultant matrix. The first module is configured to, based on first decoding statuses of multiple bytes in the resultant matrix, determine second decoding statuses of bytes proximate to failed bytes of a feedback matrix. The feedback matrix is generated based on the resultant matrix. The first module is configured to mark selected ones of the failed bytes as erasures based on the second decoding statuses. The second module is configured to correct one or more of the bytes marked as erasures during the second decoding iteration.

Abstract: New and useful methods and systems for reading optical discs, such as multi-layer Blu-ray discs are disclosed. For example, in an embodiment a device for reading two-layered optical discs includes a laser diode capable of emitting light, a set of optics including a fixed collimator, the set of optics providing a numerical aperture (NA) of substantially less than 0.85, and a detector for detecting laser light focused on a two-layer optical disc to produce a stream of detected bits.

Abstract: New and useful methods and systems for providing improved performance of a Viterbi device are disclosed. For example, in an embodiment a Viterbi device includes metric circuitry configured to determine branch metrics using at least one of a variance signal based on both received data and detected data of the Viterbi device and a priori probabilities of available state transitions within a trellis of the Viterbi device.

Abstract: Aspects of the disclosure provide an apparatus. The apparatus includes a collimator configured to have a plurality of positions, and a controller configured to control the collimator to move to a predetermined position associated with a data layer of an optical storage medium to collimate a light beam. The collimated light beam is then focused onto the data layer of the optical storage medium.

Abstract: In a perpendicular magnetic recording system, the data that is being written by the write channel is fed back into the read channel. The read channel processes the data and decides if the written sequence is likely to have very poor DC characteristics. If that is the case, the write channel changes a scrambler seed and rewrites the data using the new scrambler seed. The data may also be inspected for patterns that might cause large baseline wander before being written to disk, i.e., in the write channel. A data sequence may be repeatedly scrambled and encoded until an acceptable level of estimated DC-wander has been achieved. The data sequence may then be written to disk.

Abstract: A method and device for determining frequency error to extend the pull-in range of a timing recovery circuit for a storage device such as an optical disc drive. A code associated with a storage format of the storage device is detected, and the distance between occurrences of the code is determined. The calculated distance is compared with the expected distance to determine the difference. Based on the difference, the frequency error is determined.

Abstract: Aspects of the disclosure can provide a method for generating an offset correction signal with a reduced circuit footprint. The method can include converting samples of a wobble signal into digital values having a reduced number of bits, integrating the digital values having the reduced number of bits over a specified time interval to determine an error signal, and generating an offset correction signal based on the determined error signal.

Abstract: Aspects of the disclosure provide a signal processing circuit. The signal processing circuit includes an analog to digital converter (ADC) configured to receive an analog input signal, sample the analog input signal based on a sampling clock signal, and convert the sampled analog input signal into a digital output signal, an equalizer configured to equalize the digital output signal, a phase-shift module configured to phase-shift the equalized digital output signal based on a phase-shift signal, and a timing compensation module coupled to the phase-shift module to detect a timing error, and to adjust the phase-shift signal based on the timing error.

Abstract: Aspects of the disclosure provide a signal processing circuit that includes a signal processing circuit includes a processing path configured to process an electrical signal to produce input data samples, and a feed-forward correction module configured to delay the input data samples to produce delayed data samples, to apply the delayed data samples to a timing loop during periods when a profile variation of the data samples is not detected, and to apply the input data sample to the timing loop during periods when a profile variation of the data samples is detected.

Abstract: Aspects of the disclosure provide an apparatus. The apparatus includes a pick-up unit, such as an optical pick-up unit, a wobble channel and a defect detector. The pick-up unit generates a push-pull signal corresponding to a wobbled track of a storage medium. The wobble channel includes circuits to receive the push-pull signal, obtain a wobble signal from the push-pull signal, and calculate a wobble amplitude metric based on the wobble signal. The defect detector compares the wobble amplitude metric to a threshold to detect wobble defects.

Abstract: An offset correction is automatically determined and routinely updated to reduce or eliminate data retrieval errors that may be caused by low level distortion in optical disc data storage recording, re-recording and retrieval system. An offset control loop is provided for reading information from a modulated wobble signal with which the data is recorded to an optical disc data storage medium to provide detection of an offset and correction of that offset to facilitate implementation of precise timing synchronization and/or encoded information contact in the system. The offset detector measures a wobble signal and mathematically converts detected information regarding the measured wobble signal to an offset correction by integrating the wobble signal over a specific time interval and comparing the integrated value to an expected integrated value. The integration may be performed over at least one period of the sinusoidal wobble signal, and the correction added to the wobble signal.

Abstract: A defect is detected on a storage medium of a disk drive. A location of the defect is determined, within a smallest addressable unit of data stored on the storage medium. An indication of the location is stored in a memory. A location of a sensor of the disk drive relative to the data stored on the storage medium is monitored. A response of at least one of a defect detector of the disk drive, a read channel controller of the disk drive, and a servo controller of the disk drive is changed based on the location of the sensor relative to the data stored on the storage medium and the stored indication of the location of the defect.

Abstract: A timing loop for generating a channel clock signal for driving an analog to digital converter (ADC) includes a slicer bias loop configured to generate an asymmetry compensation signal for a digital output signal from the ADC, the first adder configured to asymmetrically compensate the digital output signal based on the asymmetry compensation signal from the slicer bias loop, a limit equalizer configured to limit a boost range of the asymmetrically compensated digital output signal from the adder, a slicer configured to generate a temporary decision signal based on the asymmetrically compensated digital output signal from the limit equalizer, a phase detector configured to generate a timing error signal based on the asymmetrically compensated digital output signal from the limit equalizer and the temporary decision signal from the slicer; and the first filter configured to generate a clock signal for driving the ADC based on the time error signal from the phase detector.

Abstract: A sync mark detector for detecting a sync mark having alternative polarities includes an input terminal receiving data bits, wherein the data bits include constant bit groups and each constant bit group includes consecutive bits of the same logic value, the first unit outputting constant bit length values that are representative of bit lengths of constant bit groups, respectively, the second unit outputting combined bit length values, wherein each combined bit length value is representative of a sum of two consecutive constant bit length values, the third unit comparing each combined bit length value to a largest previous combined bit length value to determine a largest combined bit length value, the fourth unit determining a threshold value based on the largest combined bit length value, and the fifth unit outputting a sync mark detection signal when an individual combined bit length value is larger than the threshold value.

Abstract: Aspects of the disclosure provide a method for detecting land pre-pits. The method includes detecting, based on a land pre-pit threshold, a land pre-pit data stream from a signal responsive to land pre-pits on an optical medium, comparing a characteristic of the detected land pre-pit data stream in a specific number of wobble periods with a pre-determined land pre-pit characteristic in the specific number of wobble periods, and adjusting the land pre-pit threshold based on the comparison.