Abstract: Improved dither detection, measurement, and voltage bias adjustments for an electro-optical modulator are described. The electro-optical modulator generally includes RF electrodes and phase heaters interfaced with semi-conductor waveguides on the arms of Mach-Zehnder interferometers, where a processor is connected to output a bias tuning voltage to the electro-optical modulator for controlling optical modulation. A variable gain amplifier (VGA) can be configured with AC coupling connected to receive a signal from a transimpediance amplifier (TIA) that is configured to amply a photodetector signal from an optical tap that is used to measure an optical signal with a dither signal. The analog to digital converter (ADC) can be connected to receive output from the VGA. The processor can be connected to receive the signal from the ADC and to output the bias tuning voltage based on evaluation of the signal from the tap.

Abstract: Novel tools and techniques are provided for implementing synchronization signal (“Sync Mark”) detection using multi-frequency sinusoidal (“MFS”) signal-based filtering. In various embodiments, a computing system may detect a location of a Sync Mark within a data signal, by using MFS signal-based filtering and a sliding window comprising successive search windows each having a bit length corresponding to a bit length of the Sync Mark to identify a portion of the data signal having a magnitude indicative of the Sync Mark. The computing system may refine the location of the Sync Mark within the data signal, by performing a phase measurement on the identified portion of the data signal having the magnitude indicative of the Sync Mark to identify a sub-portion of the identified portion of the data signal, the identified sub-portion having a phase indicative of the Sync Mark, the phase measurement being performed based on the MFS signal-based filtering.

Abstract: The technology disclosed herein pertains to a system and method for managing off-track retry. An implementation of a method of determining offset direction for read off-track retry includes storing analog to digital converter (ADC) values of data read from a data sector by a data reader in a read channel buffer, calculating an indicator value of the distribution of the ADC values, determining an amount of offset for the data reader based on the indicator value, and moving the data reader by the amount of offset before performing a read retry operation.

Abstract: An abnormality determination device includes: an oscillating signal sending unit configured to send out an oscillating signal which causes a rotary shaft of a servomotor to rotate and swing in a predetermined pattern, to a motor control unit configured to control the servomotor; a measuring unit configured to measure a physical quantity representing the state of the servomotor when the rotary shaft of the servomotor is swung; a comparing unit configured to compare a measurement signal of the measured physical quantity with a reference signal; and an abnormality determination unit configured to determine occurrence of an abnormality in a drive system which includes the servomotor and the motor control unit and ranges from a driven object to be driven by the servomotor to the motor control unit, based on comparison result from the comparing unit.

Abstract: According to one embodiment, a hard disk drive includes a disk including a plurality of data areas, and a plurality of servo areas between the plurality of data areas, an arm holding a write head and a read arm, and a positioning module which positions the read head or the write head by rotating the arm, wherein the positioning module positioning the write head by positioning the read head, and adjusting a position of the read head or the write head, based on an output of the read head located in a data area between two servo areas adjacent in a peripheral direction, of the plurality of servo areas.

Abstract: Various embodiments provide the position error signal (PES) that is generated by the data read channel that uses internal signals such as analog-to-digital signals, recovered data bits and signals or other internal signals to determine read head off-track metrics. Several different metrics can be utilized including a normalized norm metric, a normalized cross correlation metric, and a cross correlation with detected data metric. These metrics can be utilized to determine off-track shift of one or more read heads such that the read head position can be corrected.

Abstract: In a servo control loop, servo burst signals that are read from a plurality of servo burst patterns that include a split servo burst pattern contain frequency acquisition error. The frequency acquisition error is at least partially removed to generate a frequency acquisition error compensated position error signal (PES).

Abstract: Data is read from a track of a magnetic recording medium via multiple read transducers located at different positions on a read head. The multiple read transducers are substantially positioned over the track when reading the track. The multiple read transducers have different design characteristics manifesting in differences in at least one of magnetic and electrical behavior of the multiple read transducers. One or more signals originating from the multiple read transducers are combined to assist in decoding the data.

Abstract: Apparatus and method for optimizing read channel parameters in a storage device. In some embodiments, a method includes obtaining raw error rate data for different read channel parameter values in each of a plurality of zones of a memory. The raw error rate data for each of the different reach channel parameter values are filtered to provide a sequence of second order polynomial curves with smoothed data points in each of the zones. A second order regression is applied to the smoothed data points in each of the zones to provide a sequence of regression curves. An optimal read channel parameter value for each of the zones is selected using the sequence of regression curves, and the optimal read channel parameter values are used during subsequent read operations to retrieve data stored in the zones.

Abstract: According to various embodiments, a method for reading data from a storage medium using a reader, wherein the reader includes at least one reader head, may be provided, wherein the storage medium includes a plurality of tracks. The method may include: reading a first signal with a reader head of the reader at a pre-determined position of the storage medium; reading a second signal with a reader head of the reader at the pre-determined position of the storage medium; and determining data stored at the pre-determined position of the storage medium based on the first signal and based on the second signal.

Abstract: A hard disk drive circuit includes first and second inter-track interference detection modules. The first inter-track interference detection module is configured to generate a first measured inter-track interference value based on a first read signal from a first read sensor positioned over a magnetic medium. The second inter-track interference detection module is configured to generate a second measured inter-track interference value based on a second read signal from a second read sensor positioned over the magnetic medium. A position error signal generation module is configured to generate a position error signal based on the first measured inter-track interference value and the second measured inter-track interference value. An arm control module is configured to control rotation of an arm in response to the position error signal. The first read sensor and the second read sensor are located at a distal end of the arm.

Abstract: A method for enhancing read performance in an ARMR system includes: obtaining a first reader offset profile corresponding to a first reader of a multi-reader array head in the ARMR system; obtaining at least a second reader offset profile corresponding to at least a second reader of the multi-reader array head in the ARMR system; combining the first and second reader offset profiles to generate a combined reader offset profile; and controlling a location of the multi-reader array head in the ARMR system relative to at least one target track associated with a magnetic storage medium to be read as a function of a peak amplitude of the combined reader offset profile.

Abstract: A bit-patterned media (BPM) magnetic recording disk has two sizes of dots of magnetic material. The large and small dots are formed together in a hexagonal-close-packed (HCP) pattern. In the data regions none of the larger sized dots are adjacent one another; however in the servo regions some of the larger sized dots are adjacent one another. The adjacent larger sized dots form blocks that provide large amplitude “bursts” as the readback signal, as required for servo burst fields. The disk is made by imprint lithography using an imprint template, which can be made by directed self-assembly (DSA) of a block copolymer (BCP). The imprint template has two sizes of recesses, resulting in BPM disks with two sizes of dots. After the disks are imprinted they are exposed to a DC magnetic field, which magnetizes all the dots in the same direction.

Abstract: A data processing system includes a cross-correlation calculator operable to calculate cross-correlations between an input signal and each of three different sync patterns associated with a target track and neighboring tracks, a detector operable to select a largest of the cross-correlations, a threshold comparator operable to compare the cross-correlations with a threshold to determine a direction of any position error of a read head, and a position error estimator operable to estimate a position error of the read head based at least in part on the cross-correlations.

Abstract: A disk drive is disclosed comprising a disk comprising a plurality of data tracks defined by servo sectors. Each servo sector comprises a periodic preamble recorded at a first frequency, servo data, a periodic reference pattern recorded at a second frequency different from the first frequency, and at least one servo burst. A servo sector is processed by processing the periodic preamble to extract the servo data, demodulating the servo burst in response to the periodic reference pattern, generating a position error signal based on the extracted servo data and the demodulated servo burst, and measuring a fly height of the head based on the periodic reference pattern.

Abstract: Systems and methods for improving accuracy of head positioning using existing servo patterns are provided. In one embodiment, a method for improving read head positioning is provided that comprises: writing a series of tracks over a range of read offsets to be calibrated; measuring a set of raw track profiles from the series of tracks; sampling the set of raw track profiles at a series of signal amplitude levels; constructing a reference track profile from the set of sampled track profiles; calculating a set of read offset deltas from each sampled track profile; merging the sets of read offset deltas into a set of average read offset deltas; and converting the set of average read offset deltas into a read offset correction table. A similar method for improving disk write head positioning is also provided which utilizes such a read offset correction table to eventually create write offset correction table.

Abstract: An information device includes a slider (100) including a first metal antenna (103a), a second metal antenna (103b), and a heater (107) configured to vary the distance between the first metal antenna (103a) and the second metal antenna (103b) in a direction orthogonal to a track direction on the surface of a disk (104), and an arm motor (120) configured to move the slider (100) in parallel to the surface of the disk (104). The arm motor (120) and the heater (107) cause the first metal antenna (103a) and the second metal antenna (103b) to respectively follow corresponding target tracks.

Abstract: Various embodiments of the present invention provide systems and methods for recovering data from a storage medium. As an example, a data recovery circuit is disclosed that includes: a controller circuit, a data processing circuit, a selector circuit, and a combining circuit. The controller circuit is operable to position a sensor over a track of the storage medium at a first distance from the center of the track to yield a first data set, and to position the sensor over the track of the storage medium at a second distance from the center of the track to yield a second data set. The data processing circuit is operable to process a processing data set, and the selector circuit is operable to select between the first data set and a combined data set as the processing data set. The combining circuit is operable to combine the first data set with at least the second data set to yield the combined data set.

Abstract: Tuning a skew between a read head and a write head, may include setting a center value of a track according to a track density of a storage medium; writing data having a certain pattern to at least one target track and at least two tracks adjacent to the target track, while following the center value of the track; reading the data having a certain pattern from the target track by using a plurality of off track values in an off track range based on the center value of the track; and detecting an off track value having a minimum error occurrence number among error occurrence numbers with respect to the read data having a certain pattern corresponding to each of the plurality of off tracks, as an optimum off track value of the target track.

Abstract: A disk drive is disclosed comprising a plurality of disk surfaces, and a head actuated over each disk surface. An off-track read capability (OTRC) is measured for each disk surface, and a radial density of data tracks for each disk surface is selected in response to the OTRCs. A linear density of at least two disk surfaces is adjusted to balance the OTRCs across the disk surfaces.

Abstract: Systems and methods for improving accuracy of head positioning using existing servo patterns are provided. In one embodiment, a method for improving read head positioning is provided that comprises: writing a series of tracks over a range of read offsets to be calibrated; measuring a set of raw track profiles from the series of tracks; sampling the set of raw track profiles at a series of signal amplitude levels; constructing a reference track profile from the set of sampled track profiles; calculating a set of read offset deltas from each sampled track profile; merging the sets of read offset deltas into a set of average read offset deltas; and converting the set of average read offset deltas into a read offset correction table. A similar method for improving disk write head positioning is also provided which utilizes such a read offset correction table to eventually create write offset correction table.

Abstract: Writing servo wedge code to a disk is disclosed. A first selected burst demodulation window is determined. A final radial head position is computed based at least in part on the first selected burst demodulation window. Servo wedge code is written to a disk based at least in part on the final radial head position.

Abstract: A plurality of sensors are used to sense disturbances in a data storage system. An adaptive gain component is associated with each of the sensors and provides a gain for each of the sensor signals. The gain of each sensor signal is adapted, individually, based on a correlation of each given sensor signal to the position error signal. This adaptation produces a position correction signal. The position correction signal is applied to a position signal that is used to position the reading and writing components and the storage medium relative to one another. This compensates for both rotary and linear vibration disturbances at the same time.

Abstract: Cross-track deviation of a writer from a predetermined track on a recording medium is detected. A write current is adjusted based on the cross-track deviation of the writer from the predetermined track. The adjusted write current is applied to the writer to compensate for the cross-track deviation of the writer from the predetermined track.

Abstract: A bit-patterned magnetic media (BPM) includes with respect to each data track a first sub-track and a second sub-track, each sub-track comprised of a plurality of bit-islands. A transducer head placed over a data track generates a readback signal. Channel response circuitry demodulates the readback signal and detects fine positioning information based on a comparison of a readback signal generated in response to the first sub-track and a readback signal generated in response to the second sub-track.

Abstract: A disk drive is disclosed comprising a disk having a plurality of tracks, wherein each track comprises a plurality of data sectors. A head is actuated radially over the disk for generating a read signal. A first read of a data sector is performed while adjusting an amplitude of the read signal in response to a gain control setting. When an error occurs while attempting to first read the data sector, a first jog value is generated in response to the gain control setting. The head is served over the data sector in response to the first jog value, and a second read of the data sector is performed.

Abstract: According to one embodiment, a storage device includes an area demodulator and a head position demodulator. The area demodulator demodulates a first demodulation signal and a second demodulation signal having a phase difference of 90° from a read signal by a head of an area demodulation pattern recorded on a medium. The head position demodulator receives the first demodulation signal and the second demodulation signal, and outputs a phase angle indicating a direction of a vector formed in a phase plane by the first demodulation signal and the second demodulation signal as a head position signal.

Abstract: A bit-patterned magnetic media (BPM) includes with respect to each data track a first sub-track and a second sub-track, each sub-track comprised of a plurality of bit-islands. A transducer head placed over a data track generates a readback signal. Channel response circuitry demodulates the readback signal and detects fine positioning information based on a comparison of a readback signal generated in response to the first sub-track and a readback signal generated in response to the second sub-track.

Abstract: A data storage system includes a storage medium having a plurality of data sectors and a head that communicates with the data storage medium. The head produces a readback signal when reading information from the data storage medium. A computation unit extracts a distortion component of the readback signal and generates a position error signal from the distortion component.

Abstract: The invention concerns a method and a device for scanning data stored on a recording medium. The device comprises a reading head and further comprises: means to calculate an error rate of the data read by said reading head, said data being arranged as groups of data, means to align the reading head in respect with the next data to be read according to said error rate of the data read, the reading head reads at least twice some of said groups, changing position in respect with the group of data from one reading to the other, means to compare the calculated error rate corresponding to each position of the said reading head, means to align the reading head with the relative position in respect with the groups of data giving the lowest error rate in order to read the following groups of data, and the means to align the reading head adjust the frequency of the groups of data read at least twice.

Abstract: A magnetic recording disk has patterned nondata regions that are used for read/write head positioning and data synchronization. The nondata regions contain nondata islands of magnetizable material separated by nonmagnetic spaces with the nondata islands having alternating magnetization polarity in the along-the-track direction. In each nondata region, every other nondata island in the along-the track direction has the same magnetization direction, with adjacent nondata islands having antiparallel magnetization directions. The disk may be either a horizontal magnetic recording disk, wherein the antiparallel magnetization directions are in the plane of the recording layer and parallel to the along-the-track direction, or a perpendicular magnetic recording disk, wherein the antiparallel the magnetization directions are “into” and “out of” the recording layer.

Abstract: A magnetic head position control method is provided to control a magnetic head to follow the track on a DTM (discrete-track magnetic) disk by accurately detecting the eccentricity compensation amount through a simple process. An angle detection unit detects ?1 at which the relative displacement between the magnetic head and the tracks on the DTM (discrete-track magnetic) disk has a peak with no vibration data added. A vibration data calculation unit calculates first vibration data with first vibration amplitude, so that the displacement has a peak at ?2 displaced from ?1 by a predetermined value. The angle detection unit detects ?3 at which the relative displacement has a peak with the first vibration data added. A compensation data calculation unit calculates compensation data for the eccentricity of the tracks, from the detected angles ?1, ?3, the first vibration amplitude, and ?2. The position of the magnetic head is compensated according to the correction data.

Abstract: A method and apparatus for exactly compensating for a track zero position when copying a reference servo pattern in a disc drive adopting a reference servo track copying method. The method of compensating for a track zero position in a reference servo track copy system for copying a reference servo pattern in a head disc assembly into which a reference disc, on which the reference servo pattern is recorded, produced offline and at least one blank disc are assembled, includes: searching for a collision position of an actuator arm against a stopper for limiting the displacement of the actuator arm on the reference servo pattern; calculating an optimal track zero position based on the searched collision position; and copying the reference servo pattern on all disc surfaces from the calculated optimal track zero position.

Abstract: A magnetic recording disk drive uses a disk having pre-patterned servo sectors extending generally radially across the data tracks. The servo sectors include at least two position error signal (PES) bursts or fields. The phases of the PES fields in the servo readback signal are demodulated to generate a PES to control the disk drive actuator for positioning the read/write heads. Each field contains generally radially directed magnetized stripes, with each stripe comprising a plurality of discrete radially-spaced generally parallelogram-shaped islands, each island having its length oriented at an acute angle relative to a track centerline. The stripes have alternating polarity of magnetizations in the along-the-track direction.

Abstract: A disk drive is disclosed including a disk having a plurality of tracks, wherein each track comprises a plurality of servo sectors. The disk drive further comprises a head having a read element offset from a write element by a reader/writer offset. The read element is positioned over a first track and the write element is positioned over a second track. A first servo control signal is generated for servoing the head in response to the servo sectors in the first track, and first wedge repeatable runout (RRO) data is written to the second track along a substantially sinusoidal path corresponding to the reader/writer offset, wherein the first wedge RRO data are for writing data to a third track.

Abstract: Extracting transducer position information from bit patterned magnetic media includes providing a magnetic storage medium having at least one data array with multiple discrete and separated recording bits and providing the transducer adjacent the data array. A readback signal dependent upon the multiple recording bits is generated with the transducer. Determining the transducer position information further includes generating at least a first position signal and a second position signal from the readback signal.

Abstract: Embodiments of the present invention provide accurate pitch control of a servo write track. A Self-Servo-Write (SSW) according to an embodiment of the present invention determines a reference APC by reading a mark formed on the recording surface corresponding to the propagation head prior to starting the product servo pattern writing. The accurate size of the mark in the radial direction is known previously. The reference APC is for determining the track pitch, and by using the mark with the determined size, the product servo patterns can be written with a desired and accurate track pitch.

Abstract: A method for identifying adjacent track interference for a head is provided. The method comprises writing a first data track at a predetermined track position; writing a second data track two track positions away from the first data track; and validating the position of the first data track and the second data track. Upon validation the method further comprises writing a third data track between the first data track and the second data track and analyzing a signal profile of at least one of the first data track and the second data track for adjacent track interference.

Abstract: Embodiments of the present invention provide a magnetic disk drive system in which the write element leads the read element in the tangential direction of rotation of the magnetic disk. In addition, the servo sector information is preferably arranged such that information that is not needed for write operation is placed at the end of the servo sector. In this way, the servo read operation can be terminated sooner and the write operation can initiate sooner after going over the servo sector. The write element in a write operation writes data to the data sector of a track until an end of the data sector before reaching a front end of a servo sector following the end of the data sector. The read element reads information in the servo sector needed for the write operation. The write element starts writing data in a next data sector following the servo sector after the write element reaches the next data sector and after the read element has read all information in the servo sector needed for the write operation.

Abstract: A write-head positioning method includes steps of positioning a write head on a first track of a storage medium on the basis of a servo signal and writing a signal on the first track, positioning the write head on second and third tracks located adjacent to opposite sides of the first track on the basis of servo signals and writing signals on the second track and the third track, positioning the read head at positions on the first track that are set at a predetermined interval in a track-width direction, and reading a signal from the first track at each position thereof, determining a signal profile that indicates a fluctuation of output values of the signals read at the respective positions on the first track, and detecting a peak position indicating a maximum output value in the determined signal profile.

Abstract: A method, and system configured to implement the method, are provided. The method includes the steps of identifying a last usable track on a surface as a function of a parameter, and defining a standoff band of tracks relative to the last usable track to obtain an achieved maximum track on the surface. The last usable track is, in exemplary embodiments, a track beyond a default maximum track on a surface of a data storage medium.

Abstract: Track pitches of all the tracks of a disk medium provided in a storage apparatus are examined in a manufacturing examination step. First of all, a target position path which varies a target track position so that the position crosses the tracks is generated, and a head actuator is subjected to feedback control so that head detection positions track the target position path. Track pitch abnormality is determined when an error between the target position path and the head detection positions exceeds a predetermined threshold value, and the track number is recorded in a track skip table of the medium. As the target position path, a target position sine-wave path having the amplitude of the width of plural tracks is generated in synchronization with rotation of the medium. As another target position path, a target position straight-line path which passes each track interval in certain time between the outermost and the innermost of the medium is generated.

Abstract: A disk drive comprising a moveable head, a disk, and a servo controller to control track following operations is disclosed. The disk includes a plurality of tracks in which a substantial majority of the tracks include a plurality of servo sectors utilized in track following operations. The servo controller implements a program during power-up to: calculate servo position correction values using a set of servo position correction coefficients that have been pre-selected for the disk drive based upon the class of disk drive in which the set of servo position correction coefficients have been coded into the program; store the servo position correction values in a pre-determined servo position correction look-up table in memory; and utilize the pre-determined servo bursts correction look-up table to track follow on a reserved track of the disk.

Abstract: Processing wherein a measurement signal and an erasure signal are recorded on adjacent tracks of a recordable tape 10 by one recording head HWi of n (i=1 to n) recording heads is effected on n recording heads, and measurement signals are recorded on n tracks substantially simultaneously by n recording heads HW1 to HWn in standard operation state. Then, reproducing heads with respect to thus obtained two kinds of tracks are displaced in track width directions, characteristic curves of reproduced signal waveform amplitudes of measurement signals displacement (off-track) amounts of tracks are obtained, half widths of these characteristic curves are assumed to be expedient track width and a variable Ri optimum and a variable Ri now corresponding to track widths of two kinds of tracks are obtained. Then, deviation between the variable Ri optimum and the variable Ri now is adjusted to become smaller than a desired value.

Abstract: A magnetic head having a recording head portion for recording information at an arbitrary position on a magnetic recording surface of a recording medium and also having a reproducing head portion containing a reproducing head element for reproducing the information recorded at the arbitrary position on the magnetic recording surface forms a reproducing head element, the shape of which is curved, being made after a curved shape of a magnetization pattern recorded at the arbitrary position of the recording medium. Due to the foregoing, a shape of the lead gap formed between the reproducing head element and the magnetic recording surface of the recording medium is made to substantially agree with the shape of the magnetization pattern. On the other hand, a disk apparatus having a reproducing head element is provided in which the shape of the lead gap is made to substantially agree with the shape of the magnetization pattern.

Abstract: A write-head positioning method includes steps of positioning a write head on a first track of a storage medium on the basis of a servo signal and writing a signal on the first track, positioning the write head on second and third tracks located adjacent to opposite sides of the first track on the basis of servo signals and writing signals on the second track and the third track, positioning the read head at positions on the first track that are set at a predetermined interval in a track-width direction, and reading a signal from the first track at each position thereof, determining a signal profile that indicates a fluctuation of output values of the signals read at the respective positions on the first track, and detecting a peak position indicating a maximum output value in the determined signal profile.

Abstract: Magnetic disks have a configuration in which a plurality of tracks formed of a magnetic substance are sectioned by a non-magnetic substance that does not allow magnetic write heads are of a combined type of a read head and a write head. A measurement recording unit causes the head to move across a predetermined amount at least more than one track during one lap of track, with a predetermined radial position and a track position of the magnetic disk being taken as recording start points, thereby writing measurement data while drawing a spiral path. A measurement reading unit causes the measurement data recorded in a spiral manner to be read while gradually shifting a read-beginning point within a predetermined scanning range from an inner perimeter side including the recording start points to an outer perimeter side.

Abstract: A head is moved in a lateral direction on the boundary between a separation track and a recording track on a recording medium. The separation track isolates the adjacent recording tracks from each other. A variation is detected in the output supplied from the head based on the recording track. Positional information indicating the position of the head is generated based on the variation. The output supplied from the head varies in response to the movement in the lateral direction, namely the elapsed time. The positional information can thus be generated based on the variation in the output. The generated positional information contributes to an accurate positioning in a facilitated manner. Moreover, information required to position the head can be omitted from the recording medium. The processes can be simplified in the production of the recording medium. The operation time can thus be shortened.

Abstract: In a position control device based on a current observer control for performing two degree of freedom control, deterioration of the position accuracy caused by the output delay due to computation is prevented. In the two degree of freedom control system for preventing overrun, the delay of output of the two degree of freedom control (computing delay and hardware delay of drive amplifier, D/A converter, etc.) is considered, and the estimated state of Td which is advanced by the amount of delay from the sample point of time is computed, then output is computed based on this estimated state. So even if state changes during calculation from the sample point of time, the influence of the output delay can be prevented, and highly accurate position control can be performed, therefore overrun can be prevented.

Abstract: A servo control apparatus and method controls systems at least partially on the basis of an observable variable that has an absolute value functional relationship with the controlled variable and does not change sign for positive and negative variations from a nominal value. When applied to the positional control of an object, the control system observes a value of a position error signal and maps that signal to two different potentially correct displacement values. Two estimators within the control system are initiated, one using the positive displacement and the other using the negative displacement, and the two estimators each predict the future position of the object and the corresponding position error signal for each estimated position. A new position error signal is detected and compared to the two estimated position error signals.