Abstract: A method, apparatus, and system are provided for implementing magnetic defect classification using phase modulation for hard disk drives. A magnetic media readback signal of a hard disk drive is processed to identify predefined phase modulation (PM) characteristics to implement magnetic defect classification of magnetic media bump and pit defects.

Abstract: Embodiments of the present invention relate to the detection of synchronization marks in data storage and retrieval. To detect a synchronization mark, embodiments of the present invention require both pattern matching and proper phase alignment, following a repeating synchronization field. According to one particular embodiment, proper phase alignment following a repeated four bit synchronization field, is utilized in conjunction with pattern matching, to identify a synchronization mark. By allowing a synchronization mark to be identified only with proper phase alignment at the earliest possible occurrence of the synchronization mark, accuracy of synchronization mark detection may be improved.

Abstract: The invention includes apparatus and methods that allow a data storage device perform an enhanced data recovery procedure (DRP) that includes obtaining a new digital sampling of the voltages for the failing unit of data by re-reading the analog signal and converting it to digital form using an analog-to-digital conversion (ADC) using a fixed phase clock signal. The data samples are re-interpolated using a programmable delay line. The digital values representing the voltages are stored a buffer so that the data can be processed repeatedly using varying parameters as part of the data recovery procedure. Optionally the samples stored in the buffer can be processed in the reverse direction (from end of sector to beginning of sector) without requiring modification of the standard Viterbi detector since it inherently works on data processed in either direction.

Abstract: Embodiments of the present invention relate to the detection of synchronization marks in data storage and retrieval. To detect a synchronization mark, embodiments of the present invention require both pattern matching and proper phase alignment, following a repeating synchronization field. According to one particular embodiment, proper phase alignment following a repeated four bit synchronization field, is utilized in conjunction with pattern matching, to identify a synchronization mark. By allowing a synchronization mark to be identified only with proper phase alignment at the earliest possible occurrence of the synchronization mark, accuracy of synchronization mark detection may be improved.

Abstract: Embodiments of the present invention relate to the detection of synchronization marks in data storage and retrieval. According to one embodiment, synchronization marks are detected from the output of a matched filter, upstream of the Viterbi detector. This approach avoids the delay associated with the latency of the Viterbi output, thereby allowing time to align parity framing and to properly start the time-varying trellis. Certain embodiments disclose 34- and 20-bit primary synchronization marks located at the beginning of a data region. Other embodiments disclose 16-, 20-, and 24-bit embedded synchronization marks located within a data region.

Abstract: The invention includes apparatus and methods that allow a data storage device perform an enhanced data recovery procedure (DRP) that includes obtaining a new digital sampling of the voltages for the failing unit of data by re-reading the analog signal and converting it to digital form using an analog-to-digital conversion (ADC) using a fixed phase clock signal. The data samples are re-interpolated using a programmable delay line. The digital values representing the voltages are stored a buffer so that the data can be processed repeatedly using varying parameters as part of the data recovery procedure. Optionally the samples stored in the buffer can be processed in the reverse direction (from end of sector to beginning of sector) without requiring modification of the standard Viterbi detector since it inherently works on data processed in either direction.

Abstract: A method and apparatus are provided for implementing enhanced data channel performance using a read sample buffer in a direct access storage device (DASD). Disk data is read and stored in the read sample buffer. When a data recovery procedure (DRP) starts, the stored disk read data in the read sample buffer is detected. Error correction code (ECC) checking of the detected sample buffer disk data is performed to identify correctly recovered data. Using the disk read data stored in the read sample buffer enables data recovery without identification of a sync word. Also using the disk read data stored in the read sample buffer enables data recovery with changed channel data detection settings to recover the data. The read sample buffer can be used for accumulating read disk data from more than one read operation so that at least some channel noise is averaged out.

Abstract: A system and method for transferring data between a read/write transducer and a data storage medium involves encoding a first set of data blocks of a data field according to a first coding constraint for storage on the data storage medium. The data blocks have a predetermined block size. The data field includes a last data block that stores fewer data bytes than that accommodated by the predetermined block size. The last data block is encoded according to a second coding constraint for storage on the data storage medium, such that no pad bytes are required to complete encoding of the last data block. The first set of data blocks transferred from the data storage medium are decoded according to the first coding constraint, and the last data block transferred from the data storage medium is decoded according to the second coding constraint.

Abstract: An apparatus and method for transferring data between a read/write transducer coupled to a data channel and a data storage medium eliminates the necessity of a data sector block coding pad field. A data sector is received during a read operation. A disable signal associated with a last block of the data sector is generated. In response to the disable signal, data correction, such as parity correction, to the last block of the data sector is disabled. Data correction is enabled for application to blocks of the data sector other than the last block. Generating the disable signal involves identifying the last block of the data sector, which may be accomplished by detecting a change of state of a read gate input into the data channel or by use of a counter. The apparatus and method of the present invention may be embodied within a data channel of a data storing system, such as a direct access storage system.

Abstract: A method and apparatus are provided for implementing enhanced data channel performance using a read sample buffer in a direct access storage device (DASD). Disk data is read and stored in the read sample buffer. When a data recovery procedure (DRP) starts, the stored disk read data in the read sample buffer is detected. Error correction code (ECC) checking of the detected sample buffer disk data is performed to identify correctly recovered data. Using the disk read data stored in the read sample buffer enables data recovery without identification of a sync word. Also using the disk read data stored in the read sample buffer enables data recovery with changed channel data detection settings to recover the data. The read sample buffer can be used for accumulating read disk data from more than one read operation so that at least some channel noise is averaged out.

Abstract: An apparatus and method for transferring data between a read/write transducer and a data storage medium provides for improved track format efficiency. Data is written to a data sector of the data storage medium using a write current waveform developed in the read/write transducer. The write current waveform is typically at one of several possible states following writing of the data to the data sector. According to the present invention, a transition pattern is generated and used for transitioning the write current waveform from the state following writing of the data to a known state consistent with coding constraints of the data channel. A predetermined data pattern associated with the known state of the write current waveform is written to a pad field of the data sector. The transition pattern and the predetermined data pattern are used to resolve detector and parity post-processor closure decisions during a sector read operation.

Abstract: A system and method for transferring data between a read/write transducer and a data storage medium involves encoding a first set of data blocks of a data field according to a first coding constraint for storage on the data storage medium. The data blocks have a predetermined block size. The data field includes a last data block that stores fewer data bytes than that accommodated by the predetermined block size. The last data block is encoded according to a second coding constraint for storage on the data storage medium, such that no pad bytes are required to complete encoding of the last data block. The first set of data blocks transferred from the data storage medium are decoded according to the first coding constraint, and the last data block transferred from the data storage medium is decoded according to the second coding constraint.

Abstract: An apparatus and method for transferring data between a read/write transducer coupled to a data channel and a data storage medium eliminates the necessity of a data sector block coding pad field. A data sector is received during a read operation. A disable signal associated with a last block of the data sector is generated. In response to the disable signal, data correction, such as parity correction, to the last block of the data sector is disabled. Data correction is enabled for application to blocks of the data sector other than the last block. Generating the disable signal involves identifying the last block of the data sector, which may be accomplished by detecting a change of state of a read gate input into the data channel or by use of a counter. The apparatus and method of the present invention may be embodied within a data channel of a data storing system, such as a direct access storage system.