Abstract: An embodiment of the present invention implements some or all major servo subfunctions for a storage device in integrated servo fields comprising sequences of encoded bits having selected mathematical properties. The integrated servo field is composed of a number of encoded sequences, which are members of a selected sequence set that is constrained to preferably provide some or all of the following functions: the Servo Track Mark (STM), the Position Error Signal (PES) and location information such as the track-ID. The juxtaposition of sequences in the servo wedges is additionally constrained to increase the detectability of the contribution of adjacent sequences in the read signal. The integrated servo fields can provide a Position Error Signal (PES) in relation to the center of a data track through the amplitude of the signal read for adjacent sequences.

Abstract: An embodiment of the present invention implements some or all major servo subfunctions for a storage device in integrated servo fields comprising sequences of encoded bits having selected mathematical properties. The integrated servo field is composed of a number of encoded sequences, which are members of a selected sequence set that is constrained to preferably provide some or all of the following functions: the Servo Track Mark (STM), the Position Error Signal (PES) and positional information such as the track-ID. The integrated servo fields can provide a Position Error Signal (PES) in relation to the center of a data track through the amplitude of the signal read for adjacent sequences. The servo system detects the sequences in the signal from the read head using a set of digital filters for the set of encoded sequences.

Abstract: Disk drives are described that include a hybrid servo patterns in which the augmented servo burst fields, which can be Integrated Servo sequences, that provide the PES and also supply additional information such as a SAM, LSBs of the track identifier (TID), sector number, depending on the specific embodiment. Embodiments without write-to-read gaps before the servo sector SIDs are described. The augmented servo burst fields can be read after gapless writing of the preceding data area. For seeking operations the needed bits of the TID without having to detect or decode the Integrated Servo sequences or other augmented servo burst fields. Depending on the embodiment all or the most significant bits of the track identifier can be obtained during seeks by reading the TID fields passing under a read head as the read head moves across tracks without having to detect or decode the Integrated Servo sequences.

Abstract: Disk drives are described that include a hybrid servo patterns in which the augmented servo burst fields, which can be Integrated Servo sequences, that provide the PES and also supply additional information such as a SAM, LSBs of the track identifier (TID), sector number, depending on the specific embodiment. Embodiments without write-to-read gaps before the servo sector SIDs are described. The augmented servo burst fields can be read after gapless writing of the preceding data area. For seeking operations the needed bits of the TID without having to detect or decode the Integrated Servo sequences or other augmented servo burst fields. Depending on the embodiment all or the most significant bits of the track identifier can be obtained during seeks by reading the TID fields passing under a read head as the read head moves across tracks without having to detect or decode the Integrated Servo sequences.

Abstract: Pre-patterned discrete track media for self-servo writing are described. Embodiments include land and groove patterns for two or more Integrated Servo sequence fields for each servo sector in which one of the Integrated Servo sequence fields is aligned with the data track and a second sequence is offset by one-half of a track width. The lands and grooves between the Integrated Servo sequence fields are preferably the same width as those between the data tracks to facilitate planarization. Alternative embodiments include a sync feature for each servo sector formed by a selected groove and/or land pattern as a marker for the start of the servo fields. Alternative embodiments include a bootstrap zone with servo patterns that are readable when DC-magnetized. Described methods of self-servowriting include ways to adapt to eccentricity and non-circularity of pre-patterned discrete tracks with respect to the head paths.

Abstract: An embodiment of the present invention implements some or all major servo subfunctions for a storage device in integrated servo fields comprising sequences of encoded bits having selected mathematical properties. The integrated servo field is composed of a number of encoded sequences, which are members of a selected sequence set that is constrained to preferably provide some or all of the following functions: the Servo Track Mark (STM), the Position Error Signal (PES) and positional information such as the track-ID. In one embodiment the plurality sequences encoding a location identifier such as a track-ID are distributed across a set of servo wedges. A method of encoding the location identifier using a Chinese Remainder Theorem is described.

Abstract: Pre-patterned discrete track media for self-servo writing are described. Embodiments include land and groove patterns for two or more Integrated Servo sequence fields for each servo sector in which one of the Integrated Servo sequence fields is aligned with the data track and a second sequence is offset by one-half of a track width. The lands and grooves between the Integrated Servo sequence fields are preferably the same width as those between the data tracks to facilitate planarization. Alternative embodiments include a sync feature for each servo sector formed by a selected groove and/or land pattern as a marker for the start of the servo fields. Alternative embodiments include a bootstrap zone with servo patterns that are readable when DC-magnetized. Described methods of self-servowriting include ways to adapt to eccentricity and non-circularity of pre-patterned discrete tracks with respect to the head paths.

Abstract: A magnetic recording disk drive has a position-error-signal (PES) servo pattern divided into at least two circumferentially adjacent fields that extend radially across the data tracks and include PES blocks that are DC magnetized in one direction, with each PES block having a magnetization opposite to the magnetization of its radially adjacent neighboring PES blocks. Each PES field is contiguous with and shifted radially relative to its circumferentially adjacent neighbor PES fields. Each PES block has a single DC magnetization, and the length of the magnetization is substantially longer than the length of the magnetizations in the other fields of the servo pattern.

Abstract: An embodiment of the present invention implements some or all major servo subfunctions for a storage device in integrated servo fields comprising sequences of encoded bits having selected mathematical properties. The integrated servo field is composed of a number of encoded sequences, which are members of a selected sequence set that is constrained to preferably provide some or all of the following functions: the Servo Track Mark (STM), the Position Error Signal (PES) and positional information such as the track-ID. The integrated servo fields can provide a Position Error Signal (PES) in relation to the center of a data track through the amplitude of the signal read for adjacent sequences. The servo system detects the sequences in the signal from the read head using a set of digital filters for the set of encoded sequences.

Abstract: An embodiment of the present invention implements some or all major servo subfunctions for a storage device in integrated servo fields comprising sequences of encoded bits having selected mathematical properties. The integrated servo field is composed of a number of encoded sequences, which are members of a selected sequence set that is constrained to preferably provide some or all of the following functions: the Servo Track Mark (STM), the Position Error Signal (PES) and positional information such as the track-ID. In one embodiment the plurality sequences encoding a location identifier such as a track-ID are distributed across a set of servo wedges. A method of encoding the location identifier using a Chinese Remainder Theorem is described.

Abstract: An embodiment of the present invention implements some or all major servo subfunctions for a storage device in integrated servo fields comprising sequences of encoded bits having selected mathematical properties. The integrated servo field is composed of a number of encoded sequences, which are members of a selected sequence set that is constrained to preferably provide some or all of the following functions: the Servo Track Mark (STM), the Position Error Signal (PES) and location information such as the track-ID. The juxtaposition of sequences in the servo wedges is additionally constrained to increase the detectability of the contribution of adjacent sequences in the read signal. The integrated servo fields can provide a Position Error Signal (PES) in relation to the center of a data track through the amplitude of the signal read for adjacent sequences.

Abstract: A magnetic recording disk drive has a position-error-signal (PES) servo pattern divided into at least two circumferentially adjacent fields that extend radially across the data tracks and include PES blocks that are DC magnetized in one direction, with each PES block having a magnetization opposite to the magnetization of its radially adjacent neighboring PES blocks. Each PES field is contiguous with and shifted radially relative to its circumferentially adjacent neighbor PES fields. Each PES block has a single DC magnetization, and the length of the magnetization is substantially longer than the length of the magnetizations in the other fields of the servo pattern.

Abstract: A system and method accurately clocks write data to the discrete data blocks in a patterned media disk drive. The precise time intervals between successive timing marks in the data tracks are measured by a timing mark detector that counts the integer number of write clock cycles between successive timing marks and the fractional part of a write clock cycle by detecting the phase difference between a timing mark and a reference signal. The resulting timing error is output to a write clock compensator. The write clock is capable of generating equally spaced primary phases and phases intermediate the primary phases. The compensator includes a phase rotator that controls which write clock phase is selected for output. The value in a phase register of the compensator is used to control the phase rotator to advance or retard the write clock phase, and thus to adjust its frequency and phase so as to be synchronized for writing to the data blocks.

Abstract: A system and method accurately clocks write data to the discrete data blocks in a patterned media disk drive. The precise time intervals between successive timing marks in the data tracks are measured by a timing mark detector that counts the integer number of write clock cycles between successive timing marks and the fractional part of a write clock cycle by detecting the phase difference between a timing mark and a reference signal. The resulting timing error is output to a write clock compensator. The write clock is capable of generating equally spaced primary phases and phases intermediate the primary phases. The compensator includes a phase rotator that controls which write clock phase is selected for output. The value in a phase register of the compensator is used to control the phase rotator to advance or retard the write clock phase, and thus to adjust its frequency and phase so as to be synchronized for writing to the data blocks.

Abstract: A hard disk drive (HDD) holds data using a biphase scheme. A plurality of matched filters are used to detect binary data represented by the biphase pattern without the need for synchronous sampling or equalization.

Abstract: A data recording medium has tracks with pseudo-noise (PN) sequences with good autocorrelation properties as servo information for controlling the position of the recording head. A first set of alternating tracks uses a leading pseudo-random binary sequence (PRBS), which is a PN sequence with good autocorrelation properties, and a following PRBS that is cyclically shifted from the leading PRBS. A second set of alternating tracks interleaved with the first set also has a leading PRBS and a following PRBS that is cyclically shifted from the leading PRBS, but the leading PRBS in each of the tracks in the second set is offset along-the-track from the leading PRBS in the tracks of the first set. The head positioning control system uses the leading PRBS to generate a servo timing mark (STM), the cyclic shift to generate track identification (TID), and the following PRBS from adjacent tracks to generate the head position error signal (PES).

Abstract: A data recording system uses a recording medium in which the tracks have pseudo-noise (PN) sequences with good autocorrelation properties as servo information for controlling the position of the recording head. A first set of alternating tracks uses a leading pseudo-random binary sequence (PRBS), which is a PN sequence with good autocorrelation properties, and a following PRBS that is cyclically shifted from the leading PRBS. A second set of alternating tracks interleaved with the first set also has a leading PRBS and a following PRBS that is cyclically shifted from the leading PRBS, but the leading PRBS in each of the tracks in the second set is offset along-the-track from the leading PRBS in the tracks of the first set. The head positioning control system uses the leading PRBS to generate a servo timing mark (STM), the cyclic shift to generate track identification (TID), and the following PRBS from adjacent tracks to generate the head position error signal (PES).

Abstract: A method and apparatus are provided for implementing improved phase alignment in a direct access storage device (DASD). A reference clock input is received for providing a system clock. Locking to a synchronization field of a readback signal is performed by adjusting the phase of the system clock. A timing mark is detected and then the adjusted phase of the system clock is held. Responsive to the detected timing mark, a reference delay of a predefined number and fraction of system clock periods is identified. At an end of the reference delay, a write circuit accepts data and generates write signals for a write operation. The phase of the system clock is adjusted corresponding to a predefined fractional delay and is used to run a programmable counter that counts the predefined number of system clock periods corresponding to the reference delay.

Abstract: A method and apparatus are provided for implementing improved phase alignment in a direct access storage device (DASD). A reference clock input is received for providing a system clock. Locking to a synchronization field of a readback signal is performed by adjusting the phase of the system clock. A timing mark is detected and then the adjusted phase of the system clock is held. Responsive to the detected timing mark, a reference delay of a predefined number and fraction of system clock periods is identified. At an end of the reference delay, a write circuit accepts data and generates write signals for a write operation. The phase of the system clock is adjusted corresponding to a predefined fractional delay and is used to run a programmable counter that counts the predefined number of system clock periods corresponding to the reference delay. Modifying the system clock phase corresponding to the predefined fractional delay enables a higher granularity in delay than one clock period.

Abstract: A method and apparatus are provided for dual polarity thermal asperity detection in a direct access storage device. A level threshold comparator receives a data signal from a data channel in the direct access storage device and compares sequential data samples of the data signal with a positive level threshold and a negative level threshold. Responsive to each identified consecutive data sample above the positive level threshold and responsive to each identified consecutive data sample less than the negative level threshold, a counter value is incremented. A count comparator compares the counter value with a predefined count threshold and identifies a thermal asperity event responsive to a counter value above the predefined count threshold.