Abstract: Adjusting a clock signal includes receiving a data stream, detecting a bit in the data stream using a first amount of data in the data stream, adjusting the clock signal based on the detected bit, detecting the bit in the data stream using a second amount of data in the data stream, the second amount of data comprising more data than the first amount of data, and correcting the clock signal if a result of initial detecting differs from a result of subsequent detecting.

Abstract: A methodology for designing an implementing high rate RLL codes is optimized for application to 10-bit ECC symbols, and provides rate 20/21, rate 50/51, rate 90/91 and other modulation code rates for use in magnetic recording channels. A relatively small subcode encoding—one easy to implement—is applied to a portion of the input stream, and the resulting base codeword is partitioned into nibbles that, in turn, are interleaved among the unencoded ECC symbols. Code constraints on the subcode word nibbles depend upon the values of adjacent unencoded symbols. The resulting codes provide excellent density and error propagation performance.

Abstract: Determining a phase error in a data signal includes detecting bits in an original data signal, determining a phase error in the original data signal based on the detected bits, adjusting a clock signal based on the phase error, sampling the original data signal with the clock signal to produce a sampled data signal, and repeating detecting, determining, adjusting and sampling using the sampled data signal instead of the original data signal.

Abstract: A methodology for designing an implementing high rate RLL codes is optimized for application to 10-bit ECC symbols, and provides rate 20/21, rate 50/51, rate 90/91 and other modulation code rates for use in magnetic recording channels. A relatively small subcode encoding—one easy to implement—is applied to a portion of the input stream, and the resulting base codeword is partitioned into nibbles that, in turn, are interleaved among the unencoded ECC symbols. Code constraints on the subcode word nibbles depend upon the values of adjacent unencoded symbols. The resulting codes provide excellent density and error propagation performance.

Abstract: A method reducing data format overhead in a storage device. A sequence detector includes a series of states and a path memory of predetermined length. This method includes steps of writing a predetermined shortened pad pattern at the end of a user data field pattern to a signal-degrading storage medium such as magnetic tape or disk; generating samples during read back of the user data field pattern and the shortened pattern; and, controlling the sequence detector during receipt of pad samples to converge at only one or several predetermined detector states during a convergence sequence. The convergence sequence, and the detector pad are shorter than a sequence needed to traverse the entire length of the path memory. The final state reached during the sequence can be used to provide an accurate estimate of a last user data bit of the user data field pattern.

Abstract: A discrete-time filtering method for identifying defects in a magnetic medium, comprising the steps of: reading data signals from at least a portion of the medium; sampling the data signals to generate discrete time sample data; processing the sample data in a discrete time filter to detect deviation of the signal corresponding to media defects; and comparing the deviation of the signal to one or more threshold values to identify corresponding defect types on the recording medium. The filter can be configured to have an impulse response substantially matched to deviation of the signal corresponding to media defects.

Abstract: A methodology for designing and implementing high rate RLL codes is optimized for application to 10-bit ECC symbols, and provides rate 30/31, rate 40/41, rate 50/51 and much higher modulation code rates for use in magnetic recording channels. A relatively small subcode encoding—one easy to implement—is applied to a portion of the input stream, and the resulting base codeword is partitioned into nibbles that, in turn, are interleaved among the unencoded ECC symbols. Code constraints on the subcode word nibbles depend upon the values of adjacent unencoded symbols. The resulting codes provide excellent density and error propagation performance.

Abstract: A methodology for designing and implementing high rate RLL codes is optimized for application to 8-bit ECC symbols, and provides modulation code rates including rate 32/33; rate 48/49; rate 56/57; rate 72/73; rate 80/81 and other code rates for use in magnetic recording channels. A relatively small subcode encoding—one easy to implement—is applied to a portion of the input stream, and the resulting base codeword is partitioned into nibbles that, in turn, are interleaved among the unencoded ECC symbols. Code constraints on the subcode word nibbles depend upon the values of adjacent unencoded symbols. The resulting codes provide excellent density and error propagation performance.

Abstract: A method and apparatus for encoding a sequence of 32 bit digital data words into a sequence of 33 bit code words in consonance with predetermined minimum zero run length (d) and predetermined maximum zero run length (k) for recording upon a magnetic medium within a magnetic recording channel is disclosed. The method comprises steps of dividing each data word into eight data nibbles, determining whether any data nibble contains all zeros. If no code violation, mapping the eight data nibbles to seven code nibbles and to four bits of a five bit code sub-word and setting a fifth control bit to one. If one or more code violations are present, embedding code violation locations within at least the five bit code sub-word and other code nibbles if necessary and remapping data nibbles ordinarily directed to the code sub-word and nibble locations to code locations otherwise containing the data nibbles determined to be code violations.