Abstract: An enhanced write splice for optical recording channels is disclosed. Optical control circuitry locks to previously-written data and determines the estimated write splice location. A training sequence is written to the optical medium at a location based on the estimated write splice location. The phase offset is then estimated by reading the training sequence. A new write splice location may then be calculated compensating for the phase offset estimate. Finally, the new data to be spliced may be written or overwritten to the channel at the new write splice location.

Abstract: An enhanced write splice for optical recording channels is disclosed. Optical control circuitry locks to previously-written data and determines the estimated write splice location. A training sequence is written to the optical medium at a location based on the estimated write splice location. The phase offset is then estimated by reading the training sequence. A new write splice location may then be calculated compensating for the phase offset estimate. Finally, the new data to be spliced may be written or overwritten to the channel at the new write splice location.

Abstract: A system for increasing storage capacity of an optical medium includes a demodulator module and a writing module. The demodulator module demodulates a wobble signal having a wobble period of N channel bits, has a demodulating period of M channel bits, and generates a phase error signal, where N and M are integers greater than 1, and M is greater than N. The writing module writes M bits on the optical medium during the wobble period of the N channel bits based on the phase error signal.

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: An automated capability is provided in which an offset correction is automatically determined and routinely updated in order to reduce or otherwise eliminate data retrieval errors that may be caused by low level distortion in optical disc data storage recording, re-recording and retrieval system. The capability is implemented through an improved offset control loop 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.

Abstract: The present disclosure can provide a method and an apparatus to correct wobble phase slip in an optical disc recording system during recording. The method of correcting a phase slip can include receiving a wobble signal of a first frequency, sampling the wobble signal to generate a sampled wobble signal, where the wobble signal is sampled at a second frequency that corresponds to a frequency of a sampling signal, comparing a phase of the sampled wobble signal with a phase of a controlled signal to generate a phase error, modifying the phase error by adding a phase bias, and adjusting the second frequency based on the modified phase error to reduce a magnitude of the modified phase error.

Abstract: Methods, algorithms, software, circuits, architectures, and systems for conditionally encoding information and processing conditionally encoded information. The present invention takes advantage of codes where most randomly selected data units fulfill the coding constraints. Thus, only those data units that need encoding (i.e., that do not fulfill coding constraints) are encoded, and those data units that do not need encoding (i.e., that fulfill coding constraints) are not encoded. By doing so, one may increase the density, bandwidth and/or gain of data communications, increase the error checking and/or correcting capabilities of a data communications system, and/or reduce interference in a multi-user system.

Abstract: An enhanced write splice for optical recording channels is disclosed. Optical control circuitry locks to previously-written data and determines the estimated write splice location. A training sequence is written to the optical medium at a location based on the estimated write splice location. The phase offset is then estimated by reading the training sequence. A new write splice location may then be calculated compensating for the phase offset estimate. Finally, the new data to be spliced may be written or overwritten to the channel at the new write splice location.

Abstract: A signal detector includes a detector to generate raw decisions based on a read back signal. A post-processor identifies possible defects in the raw decisions. A selector selects a portion of the possible defects, and generates modified decisions by operating on the portion of the possible defects. A decoder generates final decisions based on the modified decisions. An estimator evaluates the final decisions to determine whether a sequence in the read back signal has been decoded to a correct codeword. In response to the sequence in the read back signal being decoded to the correct codeword, the final decisions are output from the signal detector. In response to the sequence in the read back signal not being decoded to the correct codeword, the selector selects another portion of the possible defects for processing by the selector, the decoder, and the estimator.

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 signal detector is provided to detect symbols in a read back signal. The signal detector includes a first detector to generate raw decisions as a function of the read back signal and to generate at least one next best decision. A list-aided decoder generates the final decision based on both the raw decisions and the at least one next best decision from the first decoder.

Abstract: An encoder comprises a DC tracking device that generates a metric based on portions of a communication signal and an invert signal as a function of the metric, wherein the invert signal has a flip state and a nonflip state. An inverter that selectively inverts the portions based on said invert signal to reduce an average DC value of the communication signal.

Abstract: A perpendicular recording system includes a summing module that has a first input that receives a read signal. A DC correction module selectively generates a DC correction signal to reduce DC offset in the read signal. The DC correction signal is output to a second input of the summing module. A detecting module compares an output of the summing module to a predetermined threshold and selectively detects Thermal Asperity (TA).

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 bias loop is provided for automatic threshold level adjustment in data detectors, such as a slicer detectors or threshold detectors. The bias loop monitors characteristics of the data detector's output, such as its digital sum value, to generate a signal correction term, which is used to adjust the detector's input. Alternatively, the bias loop may adjust the data detector's actual threshold value.

Abstract: An apparatus, method, and system for providing dc offset reduction in a communications channel include a feedback loop to generate dc offset correction signals, which in turn are combined with an input analog signal and a processed digital signal thereby reducing dc offset. Each feedback loop may include an adaptive filter. At least one feedback loop may be responsive to an error signal that represents the difference between the delayed input of a first detector, and its output. Further, the dc offset correction signal, partially delayed, may be added to the error signal, thereby improving the response time of the dc offset correction loop.

Abstract: A device and process to compensate for asymmetrical qualities of an analog input signal, if present, and generate a timing signal. The timing signal is then used for analog to digital conversion.

Abstract: Systems and techniques relating to interpreting signals on a noisy channel. A direct current (DC) correction can be applied to an input of a post processor outside of a main read path that supplies data detector output to the post processor. A signal processor, such as a read channel transceiver device usable in a magnetic recording system, has a main read path including a signal equalizer and a data detector. A post processor is responsive to the output of the data detector, and a DC control unit applies a DC correction to an input of the post processor outside of the main read path.

Abstract: The invention provides a channel coding method for encoding systematic data for transmission in a communication channel. The systematic data has a runlength constraint. In the method, data words are permuted. Error codes are generated based upon the permuted data words. The error codes are appended to original data words to form channel input for serial transmission in the communication channel. The number of error code bits is limited to ensure the channel input meets the runlength constraint. The error code can be a parity check bit.

Abstract: An encoder comprises a buffer that stores data associated with a communication signal. A DC-Check circuit generates a metric as a function of the data. A DC tracking block generates an invert signal as a function of the metric. An inverter unit controls an inverter bit of an output of the buffer based on the invert signal such that an average DC value of the data approaches zero. The metric is selected from a group consisting of a maximum absolute value of a running digital sum of the data, a maximum DC offset introduced by a filtering operation, a maximum DC offset of a DC correction circuit, a maximum absolute value of a filtered output of the data, a maximum DC offset slope change of the running digital sum of the data, a count of the quantity of times the metric is above or below a threshold, and combinations thereof.