Abstract: Systems and methods for synchronizing write signals are disclosed. In one embodiment, a compensation system is implemented within a disk drive that receives a synchronization signal read from a patterned magnetic disk by a read head. The compensation system processes the synchronization signal to compensate for noise sensed by the read head while a write head writes to the disk based on a write signal. The adjustment module is operable to adjust the write signal based on the processed synchronization signal so that the write signal is synchronized to the pattern on the disk.

Abstract: According to one embodiment, a disk storage device includes: a disk on which a servo pattern is recorded; a head; a driver; a signal generator; a demodulator; and a controller. Position signals for detecting an offset position from a center of a track are recorded in a recording area of a servo pattern. The signal generator generates a first timing signal indicating a timing for reading the position signals. When the controller performs a seek operation for moving the head to a target track, the signal generator generates a second timing signal. The period of the second timing signal for reading each of the position signals is made shorter than that of the first timing signal. A center time of the period of the second timing signal is shifted closer to a demodulation center time corresponding to a center of the recording area than that of the first timing signal.

Abstract: A data storage medium comprises a plurality of data regions, and a plurality of servo regions configured to provide positioning information to a reading device. Each of the plurality of data regions corresponds to more than one of the plurality of servo regions. The more than one of the plurality of servo regions are configured to provide positioning information to the reading device at discrete times corresponding to a data operation of a corresponding data region.

Abstract: A method and disk drive for calibrating a phase of a clock in the disk drive. The phase of the clock in the disk drive is changed such that a rate of change for the phase is substantially constant. A pattern of data is written to a magnetic material in the disk drive after the rate of change for the phase becomes substantially constant and while changing the phase of the clock. A selected phase of the clock at which the pattern of data that is written on the magnetic material has a desired quality is identified using the rate of change for the phase, a first point in time at which a timing mark on the magnetic material is read, a second point in time at which the timing mark is read, and a third point in time at which the pattern of data has the desired quality.

Abstract: According to one embodiment, an information storage apparatus comprises a storage medium with a first servo pattern having absolute position information and a second servo pattern having relative position information, a pitch correction module configured to move a head with an initial feed pitch by using the second servo pattern by a target distance determined from the first servo pattern, and to correct the initial feed pitch based on a moving distance of the head and a target distance, a head position controller configured to position the head based on the initial feed pitch corrected by the pitch correction module and information of the first and the second servo patterns, and a recording signal generator configured to generate a control signal for making the head record the third servo pattern having the absolute position information.

Abstract: Systems, methods, and apparatuses, including computer program products, are described for, in at least one implementation, determining a measured slope of a spiral, calibrating radial spacing between servo tracks according to a relationship between a target slope and the measured slope, wherein an amount of calibration for the radial spacing varies directly with the relationship between the target slope and the measured slope, and generating servo tracks according to the calibrated radial spacing.

Abstract: According to one embodiment, a signal processing circuit processes a signal read from a magnetic disk including a servo region and a user data region, the servo region including a servo address mark, the user data region including a data sector, and includes a counter and a gate controller. The counter is configured to count a first clock when having detected the servo address mark based on the signal read from the magnetic disk. The gate controller is configured to generate a pulse for locating the data sector in synchronization with a second clock when the counter counts a first value.

Abstract: A servo controller includes a first device that determines an adjusted servo-to-servo skew value. A servo field timer increments a timer value between consecutive servo fields, receives the adjusted servo-to-servo skew value, and adjusts an incremented timer value between the consecutive servo fields based on the adjusted servo-to-servo skew value.

Abstract: In a synchronous reproduction signal processor, when a phase error between reproduction data and a clock is repeatedly detected such that a clock synchronized with a reproduction signal is generated based on the phase error, a filtering process unit (34) performs a filtering process which performs a weighed addition with respect to a phase error series prior to the current time from a phase error calculation unit (33) using, e.g., a FIR filter with a plurality of taps so as to generate a reference value under reduced influence of noise mixed in the phase error series by feedback correction. A cross detection unit (32) detects the timing with which the sampled reproduction data crosses the reference value generated by the filtering process unit (34). This allows effective use of the dynamic range of the feedbacked reference value without limiting it, and simultaneously achieves the enhancement of noise immunity.

Abstract: A read circuit including a bit detector, a synchronization mark detector, and a clock generator. The bit detector is configured to output serial bit data including a plurality of bits according to a first clock signal and stored digital data. The synchronization mark detector is configured to detect a synchronization marker in the serial bit data and output a synchronization pulse in response to the synchronization marker. The clock generator is configured to receive the first clock signal and divide the first clock signal to provide a divided clock output based on the synchronization pulse.

Abstract: Data is processed by receiving data having a value. The amplitude of the received data is adjusted using the processor based at least in part on the value of the received data to obtain modified data.

Abstract: Methods, systems, and apparatus, including computer program products are described for calibrating servos, and in some implementations, calibrating spiral servos for use in self-servo-write (SSW) processes. In one aspect, a method is provided that includes determining timing reference information on a machine readable medium, locking a clock signal to the timing reference information, detecting a spiral on the machine readable medium, determining a location of the spiral using the clock signal, and calibrating a spiral servo according to the location of the spiral.

Abstract: The relative trajectory of a transducer head over bit-patterned media (BPM) may be skewed with respect to a down-track direction on the media (i.e., skew error). In order to resolve the skew error, the presently disclosed technology measures the skew error without adding additional patterning on the media. A detector circuit detects a sequential series of data bits on a storage media. The sequential series of data bits alternate between at least two tracks on the storage media. The sequential series of data bits are sent to a timing circuit, which sets a time stamp indicating when each data bit is received using, for example, a delay chain or a voltage ramp. A time elapsed between receiving a first data bit, a second data bit, and a third data bit is tracked. Transducer head skew is adjusted based on a signal containing the time elapsed between the bits.

Abstract: Various embodiments of the present invention provide systems and methods for controlling access to a magnetic storage medium. As one example, a method for controlling access to a magnetic storage medium is disclosed that includes providing a location count indicating a location between a portion of a first servo data sector of a magnetic storage media and a portion of a second servo data sector of the magnetic storage media, and asserting an enable window signal based upon the location count.

Abstract: A system including a read module, a clock generator module, and a write module. The read module generates read signals in response to reading servo spirals from a magnetic medium of a hard disk drive. The clock generator module generates a spiral clock based on the read signals, and generates, based on the spiral clock, (i) a first write clock and (ii) a second write clock. The spiral clock has a first frequency, the first write clock has a second frequency, and the second write clock has a third frequency. The write module is configured to (i) write a first servo wedge on a first zone of the magnetic medium of the hard disk drive based on the first write clock, and (ii) write a second servo wedge on a second zone of the magnetic medium of the hard disk drive based on the second write clock.

Abstract: To synchronize a write/read frequency with media with high precision even when a write head is positioned in a different zone in a magnetic recording/reproducing device equipped with patterned media formed with writing hit patterns and having a zoned format function, a write head is positioned on a recording track in the vicinity of a boundary between zones, and the write head is positioned in a different zone from the zone in which the read head is positioned, the preamble pattern in the zone in which the read head is positioned is reproduced, a difference between frequencies of the preamble patterns of the zones is compensated to determine a write frequency used for writing data into a desired track, and then start timing for writing is determined based on a synchronization pattern obtained at the position of the read head. Other systems and methods are presented as well.

Abstract: A method for detecting a servo address mark (SAM) of a servo sector of a disk of a disk drive during a servo field sync-up operation is disclosed. The method includes: detecting a start of a preamble; opening a SAM search window to detect the SAM; and continuing to detect the presence of the preamble during a SAM search time period. Further, the method discloses that: if the preamble is detected, the SAM search window is continued; and if the preamble is not detected, and the SAM is not detected, the SAM search window is closed.

Abstract: Methods, apparatuses, and systems implementing analog techniques to decode signals extracted from servo wedges of computer-readable storage media. A digital signal representing a repeatable runout (RRO) signal included in an analog signal of a computer-readable storage medium is obtained. The RRO signal includes a preamble that represents a magnitude of the RRO signal, and data. The digital signal includes a digital representation of the preamble. An estimate of the magnitude of the RRO signal is determined based on the digital representation. The estimate is compared with a specified level to generate an error signal based on a difference between the two. The provision of the error signal, for application to a subsequent RRO signal of the computer-readable storage medium, is delayed. The RRO signal is amplified prior to being represented as the digital signal to match a value established to decode the RRO signal.

Abstract: A disk drive is disclosed comprising a disk having a plurality of data tracks, and a head actuated over the disk, the head comprising a first read element and a second read element. A data track is read to generate a first read signal emanating from the first read element and a second read signal emanating from the second read element. The first read signal is delayed relative to the second read signal to generate a delayed read signal, and the second read signal is combined with the delayed read signal to generate a combined read signal. An estimated data sequence is detected from the combined read signal.

Abstract: A preamplifier and method writes data synchronized with the passing of a write head in a magnetic storage device over bit islands in discrete patterned recording media. The preamplifier contains a write pre-driver that conditions write data, a synchronization circuit that accepts a delay offset value and a write clock and produces a delayed clock, and a write output driver that is gated by the delayed clock to produce write pulses for magnetizing the bit islands. Gating the write output driver using the delayed clock results in more accurate synchronization than delaying the write data into the preamplifier due to the reduction of the overall length and variability of interconnects and transistors in the intervening circuitry.

Abstract: A method includes writing data to a bit-patterned media at times determined by a clock having a period that is offset from a bit island period by a fixed offset to create one insertion or one deletion approximately within a predetermined number of bit islands, reading the data, and correcting the read data using error correction. An apparatus that implements the method is also provided.

Abstract: A method of generating a test pattern of data to be written to a data storage disk medium for testing includes: rotating the disk; detecting fluctuations in the speed of rotation of the disk; producing a reference clock signal in accordance with the fluctuations so as to be synchronized with the rotation of the disk; and, generating a test pattern of data using the reference clock signal as a timing reference. An apparatus for generating a test pattern of data includes a spindle for rotating a disk; a detector arranged to detect fluctuations in the speed of rotation of the disk; a processor arranged to produce a reference clock signal in accordance with fluctuations so as to be synchronized with the rotation of the disk; and, a pattern generator arranged to generate a test pattern of data using the reference clock signal as a timing reference.

Abstract: A disk drive is disclosed comprising a disk comprising a plurality of servo sectors defining a plurality of servo tracks, and a head actuated radially over the disk for generating a read signal. Each servo sector comprises a preamble comprising a first end and a second end, and each servo sector comprises a servo sync mark after the second end of the preamble. The servo tracks form a plurality of servo zones, wherein a servo data rate of the servo sectors in a first servo zone is different than a servo data rate of the servo sectors in a second servo zone. The first end of the preambles in the servo sectors are aligned along a radius of the disk across at least the first servo zone and the second servo zone.

Abstract: A timing detector adapted for timing recovery on a read-channel is disclosed to improve signal quality of an input signal and maintain a small loop latency. The timing detector selects bits within the input signal that are high quality for timing recovery and discards bits that are low quality. The selected bits are used to synchronize phase and frequency of a bit sampler with a read-back analog signal. High-pass and low-pass analysis filters may split the input signal into high-frequency and low-frequency sub-bands and equalizers may re-shape the sub-bands. High-pass and low-pass synthesis filters may construct an output signal from the high-frequency and low-frequency sub-bands. Scaling factors may correct for signal and disturbance variations in the sub-bands. A comparator may eliminate sampled bits within the detector signal that have a magnitude less than a threshold and assign a common magnitude to sampled bits that meet or exceed the threshold.

Abstract: A hard disk drive (HDD) including a magnetic disk, the magnetic disk including a data track. The HDD also includes a synchronized rewrite controller for synchronizing a plurality of rewrites of a data pattern on a location of the track of the magnetic disk and the HDD includes a write head controlled by the synchronized rewrite controller for writing the data pattern on the location of the data track and rewriting the data pattern a plurality of times on the location in synchronization with a prior writing of the data pattern on the data track.

Abstract: A magnetic storage apparatus has a reproducing head to reproduce information from a perpendicular magnetic recording medium that is recorded with servo information, eccentricity correction data and read/write data. The apparatus further has a filter part to filter a reproduced output of the reproducing head by filtering the servo information which has a differentiated waveform by a non-differentiating characteristic and by filtering the eccentricity correction data and the read/write data which have rectangular waveforms by a differentiating characteristic, a demodulating part to demodulate the servo information, the eccentricity correction data and the read/write data that are filtered by the filter part, and a servo system to carry out a control process including an eccentricity control based on the servo information and the eccentricity correction data that are demodulated.

Abstract: A hard-disk drive. The hard-disk drive includes a magnetic-recording disk including tracks on which a plurality of patterned bit-cells that are isolated magnetically are aligned at predetermined alignment pitches. The hard-disk drive includes a magnetic-recording head which is configured to follow tracks, and to write and to read data. The hard-disk drive includes a signal-processing unit which is configured to generate a recording signal based on a write-clock signal with cycles corresponding to alignment pitches of patterned bit-cells, and to output a recording signal. The hard-disk drive includes a phase-detecting unit which is configured to detect a phase of the write-clock signal when the magnetic-recording head reaches an end point of a predetermined range. The hard disk drive includes a determination-processing unit which is configured to determine success of data writing based on a difference between an expected value and a detected value of the phase of the write-clock signal.

Abstract: There is provided a recording medium playback device that includes a first binarization portion that binarizes, by a PRML method, a signal that is read from a recording medium, a second binarization portion that binarizes the signal based on a magnitude relationship to a specified threshold value, a first frame synchronization signal detection portion that detects a synchronization pattern in a first binarized data string that is produced by the first binarization portion, and a second frame synchronization signal detection portion that detects a synchronization pattern in a second binarized data string that is produced by the second binarization portion. If the synchronization pattern is not detected by the first frame synchronization signal detection portion, a signal that is derived from the synchronization pattern that is detected by the second frame synchronization signal detection portion is used as the frame synchronization signal.

Abstract: A data storage apparatus includes: a medium for storing data having synchronization marks and data blocks, the synchronization mark and the data block being allocated alternately in the circumference direction of the medium; a head writing data into or reading out data from the medium; and a processor for executing a process including: reading out synchronization marks, measuring time for the head to pass through each of the data blocks based on signals read out from each of the synchronization marks in the circumference direction, generating write/read clock for each of the data blocks, which is continuously changing in speed, by calculating difference in time for the head to pass through the each one of the data blocks and its adjacent one of the blocks on the basis of the time measured, and writing data into or reading out data from the medium in synchronization with the write/read clock.

Abstract: A magnetic recording device includes: a magnetic recording medium including a write-synchronization region and a data region; a correction-value-storage unit configured to store therein a phase-correction value for correcting a phase of the write clock; a reading unit configured to read out a signal from the magnetic recording medium; a write-clock generator configured to generate the write clock based on a write-reproduction signal which is a signal read out from the write-synchronization region by the reading unit; a phase-correction unit configured to correct the phase of the write clock generated by the write-clock generator based on the phase-correction value stored in the correction-value-storage unit; and a data acquisition unit configured to acquire data included in a data-reproduction signal which is a signal read out from the data region by the reading unit based on a clock that is generated by correcting the phase by the phase-correction unit.

Abstract: A self-servo writing circuit including a controller. The controller is in communication with a read/write head having a read element and a write element, in which the read element is radially offset from the write element by a first predetermined distance. The controller is configured to i) cause the write element to write a first set of wedges of servo data onto a disk, and ii) after causing the write element to write the first set of wedges of servo data, cause the write element to write a second set of wedges of servo data onto the disk between the first set of wedges of servo data. The second set of wedges of servo data is radially offset from the first set of wedges of servo data based on the first predetermined distance between the read element and the write element.

Abstract: When the format control circuit detects bit synchronization information in a sector to be reproduced on a magnetic disk, the format control circuit activates a read gate signal for commanding to read out the sector from the magnetic disk. When symbol synchronization information on the magnetic disk is detected, a SYNC detection circuit produces a synchronization information detection signal. The format control circuit calculates an end position of the sector on the magnetic disk on the basis of the synchronization information detection signal to inactivate the read gate signal. The data correction circuit and the decoding circuit reproduce data and ECC in the sector read out from the magnetic disk during the period that the read gate signal is active on the basis of the synchronization information detection signal to produce the data and ECC to a data bus.

Abstract: Formatting a storage disk is disclosed. A first portion of a sector of the storage disk is defined. The first portion precedes a defect and has a first length that varies based on a detected location of the defect. A second portion of the sector of the storage disk is defined. The second portion follows the defect and has a second length that varies based on the detected location of the defect.

Abstract: The present disclosure includes systems and techniques relating to magnetic recording devices, such as disk drives. A recording medium of a magnetic recording device can include multiple helicoid patterns arranged in multiple helicoid groups. A described technique includes receiving a waveform produced by a head operated with respect to the medium; determining, based on the waveform, first phase difference(s) corresponding to a first helicoid group; affecting an alignment of the head with respect to the medium based on the first helicoid group by compensating for the first phase difference(s) to maintain the alignment; determining, while compensating for the first phase differences, second phase difference(s) corresponding to a second helicoid group; and affecting, responsive to a switch from the first helicoid group to the second helicoid group, the alignment of the head with respect to the medium by compensating for the second phase difference(s) to maintain the alignment.

Abstract: In a method for causing data to be written to a non-volatile medium, first data to be encoded and written in a sector of the non-volatile medium as a codeword is transmitted to a write or read/write channel device, and a write gate signal corresponding to the sector is asserted. Asserting the write gate signal indicates to the write or read/write channel device when to write the codeword to the sector. While asserting the write gate signal to cause the codeword to be written, second data to be encoded and written to the non-volatile medium is transmitted to the write or read/write channel device.

Abstract: A method for synchronizing writing to a bit patterned media includes: reading bits from skipped blocks on the bit patterned media, using timing of bits read from the skipped blocks to update a write clock, and writing request data to physical blocks on the bit patterned media, interleaved with the skipped blocks. An apparatus that operates in accordance with the method is also provided.

Abstract: Methods and apparatus are provided for detection of a synchronization mark based on a position of an extreme distance metric. A synchronization mark is detected in a received signal by computing a distance metric between the received signal and an ideal version of the received signal expected when reading the synchronization mark, wherein the distance metric is computed for a plurality of positions within a search window; determining a substantially extreme distance metric within the search window; and detecting the synchronization mark based on a position of the substantially extreme distance metric. The distance metric can comprise a sum of square differences or a Euclidean distance between the received signal and the ideal version of the received signal.

Abstract: Methods, systems, and apparatus, including computer program products are described for calibrating servos, and in some implementations, calibrating spiral servos for use in self-servo-write (SSW) processes. In one aspect, a method is provided that includes determining timing reference information on a machine readable medium, locking a clock signal to the timing reference information, detecting a spiral on the machine readable medium, determining a location of the spiral using the clock signal, and calibrating a spiral servo according to the location of the spiral.

Abstract: A thin film magnetic recording head is fabricated by forming a substrate from opposing ferrite blocks which have a ceramic member bonded between them. This structure is then diced to form a plurality of columns, wherein each column has a ferrite/ceramic combination. Each column represents a single channel in the completed head. A block of ceramic is then cut to match the columned structure and the two are bonded together. The bonded structure is then cut or ground until a head is formed, having ceramic disposed between each channel. A ferrite back-gap is then added to each channel, minimizing the reluctance of the flux path. The thin film is patterned on the head to optimize various channel configurations.

Abstract: Various systems and methods for peak signal detection. As one example, a method for peak signal detection that includes receiving a signal is disclosed. The received signal includes a signal region where the signal is increasing in amplitude, another signal region where the signal is decreasing in amplitude, and a transitional signal region coupling the first two signal regions. In some cases, the transitional region is of zero duration and the signal transitions directly from the increasing region to the decreasing region. The method further include calculating a distance between the signal region of increasing amplitude and the signal region of decreasing amplitude, and determining a peak of the received signal that is one half the distance from the signal region of increasing amplitude.

Abstract: Patterned-media magnetic recording disks are made from a master template that has nondata regions that contain a pattern of one or more discrete nondata islands and discrete gaps, with the pattern representing a scrambled number. All disks made from the master template, or from replica molds made from the master, will have the same patterns. When the disks are DC-magnetized so that all the nondata islands are magnetized in the same direction, these patterns will include one or more of discrete magnetized nondata islands and discrete nonmagnetic gaps that are scrambled in a pseudo-random manner. During operation of the disk drive the patterns are detected by the read head and interpreted within the disk drive using knowledge of the pseudo-random scrambling function, so that reading and writing of data can occur in the conventional manner. If the disks are copied in an attempt to replicate the master template, the resulting disks will be inoperable in a disk drive because of the scrambling.

Abstract: A method and apparatus is presented to determine a lateral position of a read/write head relative to a sequential information storage medium having a servo signal encoded therein and moving adjacent to the read/write head, where the servo signal comprises a plurality of pulses. The method includes detecting the servo signal using the read/write head and calculating a timing interval between each of the pulses using a clock rate of a clock signal. The clock rate is then adjusted based upon the velocity of the sequential information storage medium.

Abstract: Timing based servo bursts of servo frames, in which the frames are arranged to be symmetric with the same number of servo stripes in each burst of a frame, are synchronized by shifting selected bits. For example, servo frames are arranged with four servo bursts with an equal number of servo stripes in each burst, the servo frames comprising two symmetric sub-frames, each sub-frame comprising two bursts of servo stripes that are parallel to each other within a burst, and the bursts are non-parallel with respect to each other; each servo burst is arranged to comprise at least one reference servo stripe; and each servo burst is arranged to comprise at least one shifted servo stripe, wherein the shift is in the same longitudinal direction with respect to at least one reference servo stripe for each burst of a frame and the opposite longitudinal direction for bursts of sequentially adjacent frames.

Abstract: Methods and apparatus are provided for performing interpolated timing recovery using a frequency and phase estimate. An analog signal representing a sector is asynchronously sampled and stored in a storage device. A retiming circuit reads the stored samples and, based on first portions of first and second timing portions of the sector, determines phase adjustments. The retiming circuit generates a signal representing the samples at the adjusted phase and determines sample shift adjustments based on the generated signal and second portions of the first and second timing portions. The retiming circuit computes start and end indices of the sector in the buffer based on the sample shift adjustment and phase adjustment. The start and end indices may be used to compute a frequency estimate. The frequency estimate and a phase adjustment is used to interpolate the asynchronous samples at the appropriate frequency and phase.

Abstract: According to one embodiment, a control method for a magnetic disk device includes writing data by varying a phase of the array period of the plurality of magnetic elements or a phase of the time period of the recording signal in one section of the track from a corresponding phase in another section of the track, reading a reproduction signal from the track, and determining a phase shift between the array period of the plurality of magnetic elements and the time period of the recording signal, based on a reproduction signal read from the one section and a reproduction signal read from the other section. In another embodiment, a magnetic disk includes a track in which magnetic elements are magnetically separated and arranged in an array period, and a phase of the array period in one section is different from a phase in another section of the track.

Abstract: In an implementation, a media drive includes bit patterned magnetic media and a module. The module is to cause data encoded by one or more error correction codes to be written on the bit patterned magnetic media with a constraint that is configured to be used to synchronize the data if a bit insertion or deletion occurs.

Abstract: In an implementation, a media drive comprises bit patterned magnetic media and one or more modules. The one or more modules are to cause data to be written on the bit patterned magnetic media in a data sector that includes a synchronization mark disposed between data blocks of the data sector.

Abstract: A hard disk drive that includes a head that is coupled to a disk. The disk drive further includes a comparator circuit that is coupled to the head. The comparator circuit receives a synchronization signal and a write clock. The comparator generates a write error signal if a comparison of the synchronization and write clock signals exceeds a threshold. The write error signal can inhibit a write operation or cause a rewrite of data.

Abstract: A disc drive system provides increased reliability by detecting and correcting errors associated with bit-patterned media. Write synchronization errors associated with bit-patterned media are addressed by including data storage for temporarily storing data that is being written to the disc drive. The data is read from both the disc drive and the storage medium and compared to detect write synchronization errors. The disc drive system utilizes the identified write synchronization errors for at least one of timing recovery, equalizer training detection, error correction code application, and error recovery.

Abstract: A read/write head for use with bit-patterned media detects write synchronization errors between a write clock and the bit-patterned media. In particular, the read/write head writes data to the bit-patterned media using a write clock. The data is then read from the bit-patterned media and used to detect write synchronization errors between the write clock and the location of bit-islands on the bit-patterned media. Based on detected write synchronization errors, the phase associated with the write clock is modified to align the write clock with the location of bit-islands on the bit-patterned media.