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.

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: Aspects of the disclosure provide a signal processing circuit that has fast response time to sudden profile changes in an electrical signal. The signal processing circuit includes a processing path configured to process an electrical signal that is generated in response to reading data on a storage medium, and a feed-forward correction module. The feed-forward correction module is configured to detect a profile variation based the electrical signal in a time window, and correct the electrical signal in the time window based on the detected profile variation.

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: A counter is configured to generate counts associated with different locations, within a smallest addressable unit of data, on a storage medium of a disk drive. A detector is configured to detect a change in a property of a signal sensed from the storage medium. A controller is configured to: determine a count of the counter corresponding to a location, within a smallest addressable data unit on the storage medium, at which the change in the property of the signal sensed from the storage medium is detected, and change a response of at least one of the detector, a read channel controller of the disk drive, or a servo controller of the disk drive based on (i) the count and (ii) the counter.

Abstract: Devices, methods, and other embodiments associated with adjusting a defect threshold are described. In one embodiment, an apparatus includes defect detection logic and threshold adjustment logic. The defect detection logic determines, by using a defect threshold, if a read channel has read data from a defective portion of an optical disc. The threshold adjustment logic adjusts the defect threshold based, at least in part, on a gain value of a gain loop associated with the read channel.

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: A timing jitter measurement circuit for measuring timing jitter in the digital domain may use an interpolator bank to over-sample a signal from a media reader, a zero crossing estimator to estimate a zero crossing moment in the output of the interpolator bank and a time interval analyzer (TIA) to calculate the timing jitter as the deviation of the estimated zero crossing moment from an expected zero crossing moment in a clock signal. The timing jitter measurement circuit may be integrated into digital circuitry since it avoids using analog devices. Consequently, it may simplify the chip design, lower power consumption and save space.

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 provide a sync mark detector. The sync mark detector includes a first unit configured to decay over time a value indicating a length of a bit format, a second unit configured to compare the decayed value with a detected length of the bit format to determine a new length, and a third unit configured to detect a sync mark based on the detected length and the new length.

Abstract: Aspects of the disclosure provide a signal processing circuit that has fast response time to sudden profile changes in an electrical signal. The signal processing circuit includes a processing path configured to process an electrical signal that is generated in response to reading data on a storage medium, and a feed-forward correction module. The feed-forward correction module is configured to detect a profile variation based the electrical signal in a time window, and correct the electrical signal in the time window based on the detected profile variation.

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: Asymmetry and offset compensation for a data signal may be performed by a compensation circuit as disclosed. A circuit can be configured to generate a compensated data signal from a data signal, and can include: an input node inputting the data signal, an offset coefficient feedback loop configured to calculate an offset coefficient based on the data signal, a scaling unit configured to scale the offset coefficient by a first predetermined value (the scaled offset coefficient representing an estimate of an asymmetry coefficient), an asymmetry coefficient feedback loop configured to calculate the asymmetry coefficient based on the data signal and an initial value, a signal selection unit that causes the circuit to calculate the compensated data signal using the asymmetry coefficient, and an output node that outputs the compensated data signal.

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 change in a property of a signal is detected, the signal having been sensed from a storage medium by a disk drive. A count is determined, the count corresponding to a first location on the storage medium at which the change in the property of the signal sensed from the storage medium is detected. The count is used to predict a second location on the storage medium corresponding to the change in the property of the signal sensed from the storage medium. Relative to the first location on the storage medium, the second location on the storage medium is closer to an actual location of a feature on the storage medium that causes the change in the property of the signal sensed from the storage medium.

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 provide a method for detecting marks. The method includes receiving a data signal from a channel. Further, the method includes matching the data signal to a template that corresponds to a predetermined pattern transmitted over the channel to detect marks, prior to decoding the data signal into a decoded bit stream.

Abstract: A system and method for adjusting the radial tilt, tangential tilt, or a combination of radial and tangential tilt of an optical detection unit in an optical disc reading system can include applying different weighting factors to different signal components depending on which detection area detects the component, measuring a value of a signal characteristic, such as signal-to-noise ratio, of two signals with different sets of weighting factors, and determining an adjustment factor to the radial tilt as a function of the of the measured signal characteristic values.

Abstract: Aspects of the disclosure provide a method. The method includes receiving regional quality information of a region on a storage medium, and adjusting a fill level threshold of a buffer based on the regional quality information. The fill level threshold is used to trigger filling the buffer with data read from the region.