Abstract: An apparatus for calibrating a noise predictive filter includes a noise-predictive filter operable to filter digital data samples to yield filtered data samples, a calibration circuit operable to calculate tap coefficients for the noise-predictive filter based at least in part on the digital data samples, and a gating circuit operable to select a portion of the digital data samples for use by the calibration circuit in calculating the tap coefficients.

Abstract: Methods and apparatus are provided for detecting a syncMark in a read channel, such as a hard disk drive. A syncMark is detected in a sector in an iterative read channel by obtaining a sector signal from a storage media, the sector signal comprising a first syncMark, data and a second syncMark substantially at an end of the sector; determining whether the first syncMark is detected in the sector signal; searching for the second syncMark if the first syncMark is not detected in the sector signal; and detecting and decoding the sector signal based on a detection of the second syncMark. The second syncMark may be positioned, for example, following data in the sector signal. The second syncMark can be searched for in a window within the signal sector that is based on an estimated location of the first syncMark.

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 provide a recording disk capable of curtailing the amount of servo data to be stored thereon, and a disk drive. According to one embodiment, servo data area sets each of a first servo data area and plural second servo data areas arranged in that order in a read direction HR are arranged successively on each of tracks of a magnetic disk. Stored in a second sector data section included in the second servo data area is data representing a distance in the read direction HR from the position of the first servo data area to that of the same second servo data area. The amount of data stored in the second sector data section is less than that of data stored in a first sector data section included in the first servo data area.

Abstract: Methods and apparatus are provided for detecting a syncMark in a read channel, such as a hard disk drive. A syncMark is detected in a sector in an iterative read channel by obtaining a sector signal from a storage media, the sector signal comprising a first syncMark, data and a second syncMark substantially at an end of the sector; determining whether the first syncMark is detected in the sector signal; searching for the second syncMark if the first syncMark is not detected in the sector signal; and detecting and decoding the sector signal based on a detection of the second syncMark. The second syncMark may be positioned, for example, following data in the sector signal. The second syncMark can be searched for in a window within the signal sector that is based on an estimated location of the first syncMark.

Abstract: An embodiment in accordance with the present invention enables storing in a memory, multi-bit data corresponding to analog signals read from a medium before being converted to single-bit data as recorded data. In an embodiment of the present invention, an AD converter is configured to convert analog signals from a magnetic disk to multi-bit data. A buffer circuit holds successively multi-bit data transferred from the AD converter toward a Viterbi decoder, and outputs the held plural multi-bit data in parallel. A SRAM for ECC is used for storing multi-bit data transferred from the buffer circuit.

Abstract: Embodiments of the present invention efficiently perform servo correction for prevention of propagation of a position error in a radial direction in self servo write (SSW). According to one embodiment, in SSW, a target position of a reference track TO in writing a servo write track TN is corrected. The target position is represented as a target value of a position signal calculated from a signal read by a read element. A signal indicating a deviation (a position error) from the target position (the target value) is referred to as PES. The SSW in this example performs correction of target positions in respective tracks using an impulse response of a servo system. Consequently, it is possible to efficiently and effectively prevent the propagation of position error in the SSW.

Abstract: Embodiments of the invention reduce the effect of the rotational jitters to write a pattern in more accurate timing in self-writing a pattern on a magnetic disk. In an embodiment of the invention, respective patterns in N sectors are first written on an inner circumferential side track as reference patterns with a default clock frequency and a default clock number (a writing interval clock number between respective patterns). The respective reference patterns are then read out plural times for measuring intervals thereof to determine an average value of intervals between the respective sectors. Using the value, a target value is calculated in each sector, which is used in wiring new patterns on the outer circumferential side at even intervals. Then, the respective reference patterns on the inner circumferential side track are read out while the new patterns are written on the outer circumferential side.

Abstract: Embodiments of the invention prevent erroneous writing/readout onto/from magnetic disks or other recording disks, even when data transfer between a controller such as an HDC, and a channel such as an R/W channel, and the read/write operation performed by the channel do not match each other in timing. In one embodiment, an HDC/MPU outputs to an R/W channel a starting instruction for data transfer to/from a head, and data that indicates data length of data to be transferred. In response to the data transfer starting instruction from the HDC/MPU, the R/W channel starts transferring, to/from the head, recorded data of the data length notified from the HDC/MPU.

Abstract: Embodiments of the present invention provide a recording disk capable of curtailing the amount of servo data to be stored thereon, and a disk drive. According to one embodiment, servo data area sets each of a first servo data area and plural second servo data areas arranged in that order in a read direction HR are arranged successively on each of tracks of a magnetic disk. Stored in a second sector data section included in the second servo data area is data representing a distance in the read direction HR from the position of the first servo data area to that of the same second servo data area. The amount of data stored in the second sector data section is less than that of data stored in a first sector data section included in the first servo data area.

Abstract: Embodiments of the invention relate to writing servo patterns onto a recording disk with a high degree of accuracy and with correct phases in a servo-pattern-writing process. An In-Drive SSW (TSSW) process is processing to write product servo patterns onto a recording disk on the basis of time aligned patterns. In the processing to write product servo patterns onto a recording disk, time intervals between time aligned patterns already written on an ID-side track are measured, and timings to write the product servo patterns onto the recording disk on the basis of the measured time intervals are determined. Product servo patterns are then written onto an OD-side track with the determined timings relative to detections of the time aligned patterns used as references. In this way, circumferential-direction positions of product servo patterns written on a track may be aligned to the corresponding circumferential-direction positions of product servo patterns written on an adjacent track.

Abstract: Embodiments in accordance with the present invention relate to suppressing effects of the rotational jitter of a rotating medium during self-writing of patterns on the medium. In one embodiment, patterns are written on a track TE first. While a clock frequency is modulated using the difference between the readout time and target time of each pattern PE on the track TE, patterns PF are written on a track TF after a calculated delay time from the readout of each pattern PE. During pattern writing on the track TF, any timing errors of the patterns PE are stored into memory. While the target time for each pattern PF on the track TF is being corrected using the stored timing errors of the patterns PE and the clock frequency is being modulated using the difference between the readout time and corrected target time of each pattern PF, patterns PG are written on a track TG after a calculated delay time from the readout of each pattern PF.

Abstract: Embodiments of the present invention provide a method of forming an initial servo-pattern for self servowrite, insusceptible to constraints of an output resolution of a driver circuit for driving an actuator, and a dynamic range. According to one embodiment, a cluster pattern made up of pattern blocks, each including a burst pattern, is written by use of a write element by pressing a head-support mechanism to a crash-stop, and a pattern block is newly written with a read element in states of being positioned at an inner peripheral side edge of the cluster pattern, an outer peripheral side edge thereof, and the center of two burst patterns included in the cluster pattern, respectively, thereby increasing a width of the cluster patterns in stages, so that an initial servo pattern for use in a propagation action is formed.

Abstract: The data possessed by a parent hard disk drive is exported to a baby hard disk drive, which is connected to the parent hard disk drive, and thus, the baby hard disk drive executes by itself an optimization/inspection process including writing of servo information. A hard disk drive is reproduced by incorporating “DNA” used for reproduction into each hard disk drive, and then, by performing self-optimization and/or self-inspection by a new hard disk drive (baby hard disk drive), according to information supplied by a finished hard disk drive (parent hard disk drive).

Abstract: Embodiments of the invention relate to measuring characteristics of a head with an actuator put in a state of being pushed against a crush stop. In one embodiment, with a head placed on an innermost ID side or with the current of a VCM sustained at a magnitude I_mid, a burst pattern is written onto a recording disk. At this stage, the gain of a VGA is equal to its maximum value Gmax. Then, while the current of the VCM is being changed gradually, the gain of the VCA is measured. As the current of the VCM becomes equal to a magnitude I_center, a read element of the head is positioned right above the burst pattern. At that time, the gain of a VGA is equal to its minimum value Gmin. As the read element is further moved to the OD side, the gain of the VGA again becomes equal to the maximum value Gmax. A read/write offset of the head is identified by the magnitudes I_center and I_mid.

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: An embodiment in accordance with the present invention enables storing in a memory, multi-bit data corresponding to analog signals read from a medium before being converted to single-bit data as recorded data. In an embodiment of the present invention, an AD converter is configured to convert analog signals from a magnetic disk to multi-bit data. A buffer circuit holds successively multi-bit data transferred from the AD converter toward a Viterbi decoder, and outputs the held plural multi-bit data in parallel. A SRAM for ECC is used for storing multi-bit data transferred from the buffer circuit.

Abstract: Embodiments of the present invention efficiently perform servo correction for prevention of propagation of a position error in a radial direction in self servo write (SSW). According to one embodiment, in SSW, a target position of a reference track TO in writing a servo write track TN is corrected. The target position is represented as a target value of a position signal calculated from a signal read by a read element. A signal indicating a deviation (a position error) from the target position (the target value) is referred to as PES. The SSW in this example performs correction of target positions in respective tracks using an impulse response of a servo system. Consequently, it is possible to efficiently and effectively prevent the propagation of position error in the SSW.

Abstract: Embodiments of the invention relate to writing servo patterns having aligned phases onto a recording disk in a process to write the servo patterns onto the disk. In one embodiment, time aligned patterns are written onto a magnetic disk on the basis of time intervals between base patterns with timings aligned to each other throughout tracks on the disk. The time aligned patterns are written onto typically servo tracks at time intervals Ts with aligned timings. Then, on the basis of these time aligned patterns, product servo patterns are written onto the disk. A time aligned pattern is written onto the disk after the lapse of a predetermined write time period since detection of a base pattern corresponding to the time aligned pattern. The write time period is determined on the basis of time intervals between base patterns on adjacent tracks.

Abstract: Embodiments in accordance with the present invention suppress an adverse influence on a pattern of a magnetic disk due to its rotational jitter and write the pattern at more accurate timing. In accordance with one embodiment, a hard disk controller/microprocessing unit (HDC/MPU) controls a clock frequency of a data clock generation circuit so that a rotational jitter of the magnetic disk be compensated when writing and reading user data. The HDC/MPU expects a detection timing of next adjacent servo sector using an error between an actual detection timing and an expected detection timing of a servo sector which has already been detected. The HDC/MPU controls the clock frequency using the expected timing and writes and reads user data between current servo sector and next adjacent servo sector according to the clock signal.