Abstract: An apparatus comprising a writer, a reader, and a sensor configured to at least sense thermal asperities of a magnetic storage medium. The apparatus includes a writer heater configured to thermally actuate the writer, a reader heater configured to thermally actuate the reader, and a sensor heater configured to thermally actuate the sensor. The thermally actuated sensor is configured to detect thermal asperities arising from the magnetic storage medium during a topographical survey of the medium. The sensor heater is configured to be rendered inoperable subsequent to the survey in response to receiving a predetermined signal while the writer and the reader heaters remain operable.

Abstract: According to one embodiment, a head flying height control method includes detecting a contact of a head with a disk while floating the head from the disk and moving the head in a radial direction of the disk, increasing a flying height of the head after detecting the contact of the head with the disk, and decreasing the flying height of the head after a state where the contact of the head with the disk is not detected continues.

Abstract: A data storage device is disclosed comprising a head and a disk comprising servo information and a reference pattern comprising a plurality of magnetic transitions. The servo information on the disk is processed to actuate the head over the disk, and a read signal is sampled from the head as the head moves across a width of the reference pattern at a substantially constant velocity to generate signal samples. The signal samples are processed to characterize a geometry of the magnetic transitions.

Abstract: A write head is tested by measuring the effect that magnetic fields have on the inductance of the write head. For example, a perpendicular write head may be placed in a magnetic field with a first angle, e.g., non-parallel and non-perpendicular, to the air bearing surface and the inductance is measured. After altering the angle of the magnetic field the inductance is again tested. In another embodiment, the angles may be parallel and perpendicular to the air bearing surface. The difference in the inductance value can be used to determine a characteristic of the write head, such as the presence of a recording pole. In some embodiments, the inductance may be measured while applying a bias current to the write head while the write head is in an external magnetic field.

Abstract: Systems and methods for conducting financial transactions using non-standard magstripe payment cards are provided. One such system includes a magnetic stripe card storing information including a serial number on a magnetic medium of the magnetic stripe card, where the stored information does not include a Primary Account Number, a card reader configured to extract information from the magnetic medium, the extracted information including the stored serial number and a magnetic fingerprint including an intrinsic magnetic characteristic of the magnetic medium, and a computer coupled to the card reader and to a server, where the computer and the server are configured to execute a requested financial transaction using the extracted information.

Abstract: An apparatus includes: a media; a head over the media; a read channel, coupled to the head, configured to extract data from the media; control circuitry, coupled to the read channel, configured to execute a read command; and wherein the read channel is further configured to: generate, based on extracting the data from the media, a data condition indicator, and provide, for use by the control circuitry, the data and the data condition indicator.

Abstract: A write head is tested by measuring the effect that magnetic fields have on the inductance of the write head. For example, a perpendicular write head may be placed in a magnetic field with a first angle, e.g., non-parallel and non-perpendicular, to the air bearing surface and the inductance is measured. After altering the angle of the magnetic field the inductance is again tested. In another embodiment, the angles may be parallel and perpendicular to the air bearing surface. The difference in the inductance value can be used to determine a characteristic of the write head, such as the presence of a recording pole. In some embodiments, the inductance may be measured while applying a bias current to the write head while the write head is in an external magnetic field.

Abstract: According to at least one embodiment, a decoding apparatus includes an error correcting module and a change module. The error correcting module decodes for correcting error of encoded data using a low-density party check code and likelihood information. The change module changes a value of the likelihood information if the value of the likelihood information is continuously smaller than a predetermined value.

Abstract: Methods for measuring media performance associated with adjacent track interference are provided. One such method includes iteratively writing data to a target track for each of a plurality of n frequencies, measuring a first signal amplitude and a first noise for each of the n sectors on the target track, writing an aggressor track pattern proximate the target track, measuring a second signal amplitude and a second noise for each of the n sectors on the target track, calculating a weighted sum for each of the signal amplitude measurements for each of the plurality of n frequencies, and calculating a weighted sum for each of the noise measurements for each of the plurality of n frequencies, and repeating the writing the aggressor track pattern, the measuring the second signal amplitude and the second noise, and calculating the weighted sums for preselected numbers of times.

Abstract: A method for detecting an information pattern includes obtaining a first sample stream and a second sample stream. The first sample stream and the second sample stream are obtained by sensing recorded information at a target location of a storage medium using a first sensor and a second sensor, respectively. A first metric is computed by comparing the first sample stream to a reference pattern representative of a target information pattern to be detected. A second metric is computed by comparing the second sample stream to the reference pattern. A combined metric is computed by combining the first metric and second metric using a weighting function. The target information pattern is detected using the combined metric.

Abstract: Inter-track interference cancelation is disclosed, including: receiving an input sequence of samples associated with a track on magnetic storage; using a processor to generate inter-track interference (ITI) data associated with a first side track including by performing a correlation between the input sequence of samples and a sequence of data associated with the first side track.

Abstract: A cluster size measurement method includes writing a first pattern of a first size of a first number of magnetic clusters. A second pattern of a second size of a second number of magnetic clusters is written, wherein the second plurality of clusters includes clusters of the first number of clusters and a switched cluster. A cluster size of the switched cluster is automatically determined by contrasting the first size and the second size.

Abstract: Technologies are described herein for detecting adjacent track interference in a storage device using a size-adjustable sliding window. A value for an inter-track interference factor associated with at least one adjacent track is determined for a first area of a data track of the storage device. The first area may encompass a plurality of sectors of the data track. Next, it is determined whether the value of the calculated inter-track interference factor is greater than a threshold value, and if so, an indication of inter-track interference corresponding to the first area is stored in the storage device.

Abstract: A hard disk drive has disks with data sector preambles that allow for inter-track interference. The same data sector preamble is used for all data sectors in a track but the preamble in each track is different from the preamble in radially adjacent tracks. In a first embodiment each preamble includes a synchronization field (SF) and synchronization mark (SM) that are the same in each track but different from the SF and SM in radially adjacent tracks. Only two unique SFs and two unique SMs are required, with the two SFs and two SMs alternating in radially adjacent tracks. In a second embodiment the preambles are “integrated”, meaning that the preamble is a sequence of bits that does not include separate dedicated fields, like SF and SM. The preamble bit sequences are decoded using matched filters to provide bit synchronization and start-of-data information.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of data tracks. A plurality of consecutive data tracks are written, and after writing to the plurality of consecutive data tracks, a first number of the consecutive data tracks are read and a second number of the consecutive data tracks are skipped, wherein the second number of data tracks are interleaved with the first number of data tracks. Defects in the data tracks are detected in response to reading the first number of data tracks.

Abstract: A system including a first filter module configured to receive an input signal including (i) a first shift in a DC level of the input signal and (ii) a second shift in the DC level of the input signal. The first shift has (i) a first magnitude and (ii) a first duration. The second shift has (i) a second magnitude and (ii) a second duration. The second magnitude is different than the first magnitude. The second duration is greater than the first duration. The first filter module is configured to pass the first shift. The second filter module is configured to detect one or more of (i) the first shift and (ii) the second shift, and in response to detecting one or more of (i) the first shift and (ii) the second shift, filter one or more of (i) the first shift and (ii) the second shift.

Abstract: Various aspects of the present disclosure are directed toward an apparatus, such as a disc drive, including a disc having multiple tracks, a magneto-resistive transducer assembly, and multiple-track signal correction circuitry. The multiple-track signal correction circuitry compensates for asymmetry in a readback signal of read data stored in at least one of multiple tracks based on different correction coefficients for respective ones of the multiple tracks.

Abstract: Systems and methods for testing magnetic media disks during manufacturing using sliders with temperature sensors are provided. One such method involves scanning a surface of a selected disk of a plurality of magnetic media disks using a slider including a magnetic transducer and a temperature sensor, counting a number of the surfaces scanned, determining, during the scanning, whether a threshold crossing event has occurred by determining whether a signal from the temperature sensor signal is not within a preselected range, counting, during the scanning, a number of threshold crossing events, storing, if the number of threshold crossing events is greater than a preselected events limit, the number of surfaces scanned, stopping, if the number of surfaces scanned is greater than a surfaces scanned threshold, the scanning, and returning, if the number of surfaces scanned is less than or equal to the surfaces scanned threshold, to scan a next selected disk.

Abstract: A data signal comprising an even component and an odd component with differing amplitudes is received at a main automatic gain controller (AGC). The even component is adjusted by a first interleaved AGC and the odd component is adjusted by a second interleaved AGC such that even and odd component amplitudes are substantially equal. Amplitude adjusted even and odd components are recombined to define a data signal with components having substantially equal amplitudes. The even and odd components can be generated by a read transducer moving relative to a magnetic storage medium comprising tracks defined by discrete and spaced-apart recording bits arranged in an interspersed pattern. A read channel separates the data signal into even and odd samples such that a gain can be independently adjusted for each of the even and odd samples to compensate for asymmetry between the even and odd samples.

Abstract: The present invention is related to systems and methods for adaptive parameter modification in a data processing system.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks. The head comprises a touchdown element operable to generate a touchdown signal. The touchdown signal is amplified by a gain to generate an amplified touchdown signal, and a touchdown event is detected by comparing the amplified touchdown signal to a threshold. During a calibration operation, the gain is adjusted and the threshold is adjusted until the amplified touchdown signal does not exceed the threshold. During a normal operation, the touchdown event is detected based at least partly on the adjusted gain and the adjusted threshold.

Abstract: Hardware-based methods and apparatus are provided for inter-track interference mitigation in magnetic recording systems. Inter-track interference (ITI) is mitigated in a magnetic recording system by obtaining ITI cancellation data; and providing the ITI cancellation data to an ITI mitigation circuit using a write data path in the magnetic recording system. The write data path can optionally operate substantially simultaneously with the read data path performing the read operation. The ITI cancellation data comprises, for example, user data and/or media data.

Abstract: According to one embodiment, a first defect detector executes a first scan test. The first scan test includes detecting a defect on a disk using a head disk interference sensor by scanning the disk using a head. The first scan test further includes identifying a range of cylinders indicated by servo data read by a read element when the defect is detected, as a first detected location of the detected defect. A compensator corrects the first detected location to a second detected location based on a position difference. The second detected location corresponds to a position of the head disk interference sensor at a time of detection of the defect.

Abstract: A data processing circuit with flaw robust burst field demodulation includes a burst integration circuit operable to calculate burst integration results for a servo data burst field, a comparison circuit operable to determine whether an absolute value of the burst integration results falls outside a window, and an error indicating circuit operable to indicate that a media flaw has been detected when the absolute value of the burst integration results fall outside the window.

Abstract: The present inventions are related to systems and methods for data processing, and more particularly to data processing using distortion-correction loops with saturation-based assistance.

Abstract: Various embodiments of the present invention provide systems and methods for data processing. As an example, a data processing circuit having a data detection circuit is disclosed that includes: a scaling circuit, a soft output calculation circuit, and a factor calculation circuit. The scaling circuit is operable to scale a branch metric value by a scaling factor to yield a scaled output. The soft output calculation circuit is operable to calculate a soft output based at least in part on the scaled output. The factor calculation circuit operable to modify the scaling factor based at least in part on the soft output.

Abstract: A method and system for estimating a zero gain start (ZGS) bias in a read channel is disclosed. The method may include: receiving preamble samples within a fixed-length window selected for ZGS calculation; calculating an energy associated with a 2T frequency in the preamble samples; calculating an energy associated with non-2T frequencies in the preamble samples; and calculating the ZGS bias based on the energy associated with the 2T frequency in the preamble samples and the energy associated with non-2T frequencies in the preamble samples.

Abstract: Methods, systems and computer program products for performing hybrid defect detection are disclosed. In some implementations, an apparatus includes a signal module to process data signals corresponding to data on a storage medium to generate signal samples. The apparatus includes a first defect detector to identify a first portion of the signal samples, determine a number of the signal samples in the first portion that are associated with abnormal signal characteristics, and generate a first output based on the number of the signal samples in the first portion that are associated with abnormal signal characteristics. The apparatus includes a second defect detector to identify a second portion of the signal samples different from the first portion, and generate a second output based on a correlation between data bits and signal samples in the second portion.

Abstract: Approaches for a flying height control scheme in a hard-disk drive (HDD) device. The flying height control scheme utilizes an embedded contact sensor (ECS) to characterize the topography of a magnetic-recording disk at various flying heights of a head slider over a corresponding disk. A relation between a particular flying height and a corresponding ECS value which characterizes the media topography at that particular flying height is represented in disk topography data. The disk topography data is accessed and used for active flying height control for the head-disk interface in view of the current ECS value.

Abstract: A data storage device includes a storage medium on which data is stored in overlapping tracks, and a medium controller that directs storage of data on, and reading of data from, the storage medium, including encoding data being stored and decoding data being read. The decoding includes, when reading a first track, cancelling interference from a second track that overlaps the first track. The data storage device also includes a host controller in communication with the medium controller. The host controller includes memory that stores data decoded, and data to be written, by the medium controller. Communication between the medium controller and the host controller includes signals derived from data on said first and second tracks for facilitating the cancelling. A method of operating a data storage device includes, when reading a first track, facilitating the cancelling by communicating signals derived from the data on the first and second 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: A system including a first circuit, a second circuit, an amplifier, and a summer. The first circuit is configured to (i) select a first portion of a signal, and (ii) generate a first compensation for asymmetry in the first portion of the signal using a first function, where the first function is a modulus function. The second circuit is configured to (i) select a second portion of the signal, and (ii) generate a second compensation for asymmetry in the second portion of the signal using a second function, where the second function is different than the first function. The amplifier amplifies the signal and provides an amplified output. The summer is configured to add (i) the first compensation, (ii) the second compensation, and (iii) the amplified output, where (i) the first circuit, (ii) the second circuit, and (iii) the amplifier are connected in parallel to the summer.

Abstract: A magnetic media tester comprising a Laser Doppler Vibrometer (LDV) head; and a magnetic read head; the LDV head and the magnetic read head being configured for obtaining correlatable data of a region on a magnetic disk.

Abstract: An assembly and method to determine adjacent track coherence is disclosed. The assembly includes coherence circuitry configured to receive phase and frequency offsets from timing recovery circuitry and determine an inter-track phase and frequency coherence between the encoded data on a first track and the encoded data on a second track adjacent to the first track utilizing the frequency and phase offsets from the timing recovery circuitry for the output signals corresponding to the first and second tracks.

Abstract: A disk drive is disclosed comprising a head actuated over a disk surface, the head comprising a fly height actuator for controlling a fly height of the head, and a ramp for parking the head. A ramp procedure is executed by applying a control signal to the fly height actuator to decrease the fly height and receiving a corresponding fly height signal, and detecting whether the head is on the ramp in response to the fly height signal.

Abstract: Various embodiments of the present invention provide systems and methods for data processing. For example, some embodiments of the present invention provide clock generation systems that include: a first clock multiplier circuit, a second clock multiplier circuit, a modulus accumulator circuit, and a data clock phase control circuit. The first clock multiplier circuit is operable to multiply a reference clock by a first multiplier to yield a first domain clock, and the second clock multiplier circuit is operable to multiply the reference clock by a second multiplier to yield a second domain clock. The modulus accumulator circuit is operable to yield a value indicating a fractional amount of the second domain clock that an edge of the second domain clock is offset from a trigger signal. The data clock phase control circuit is operable to phase shift the second domain clock by a phase amount corresponding to the fractional amount.

Abstract: According to an aspect of the present disclosure, a system for correcting for DC characteristics of a magnetic recording system includes: circuitry implementing at least a portion of a write channel of the magnetic recording system; and circuitry configured to process output data of the write channel circuitry in accordance with a read channel of the magnetic recording system and repeatedly trigger re-writing through the write channel circuitry using different ones of a plurality of available data scramblings until a measured baseline wander exceeds a target threshold.

Abstract: Various embodiments of the present invention provide systems and methods for data processing. As an example, a data processing circuit is disclosed that includes a noise predictive filter circuit, a data detector circuit, and a first and a second pattern dependent adaptive target circuits. The noise predictive filter circuit includes at least a first pattern dependent filter circuit operable to perform noise predictive filtering on a data input for a first pattern using a first adaptive target to yield a first noise predictive output, and a second pattern dependent filter circuit operable to perform noise predictive filtering on the data input for a second pattern using a second adaptive target to yield a second noise predictive output. The data detector circuit is operable to apply a data detection algorithm to the first noise predictive output and the second noise predictive output to yield a detected output.

Abstract: Determining a parameter associated with whether a portion of a storage device is defective is disclosed. Determining comprises: obtaining known data associated with the portion; reading back from the portion to produce a read-back waveform; decoding the read-back waveform, including producing statistical information; and determining a parameter associated with whether the portion is defective based at least in part on the statistical information.

Abstract: A system including a first filter module and a second filter module. The first filter module is configured to (i) pass a first DC shift in an input signal and (ii) convert a second DC shift in the input signal to a first component and a second component. The first DC shift is shorter in duration than the second DC shift. The second filter module is configured to detect one or more of (i) the first DC shift and (ii) the first component and the second component of the second DC shift. In response to detecting one or more of (i) the first DC shift and (ii) the first component and the second component of the second DC shift, the second filter module is configured to filter one or more of (i) the first DC shift and (ii) the first component and the second component of the second DC shift.

Abstract: In a magnetic reading/writing device, a controller derives at each radius of a recording medium a slope of a curve of track-averaged write performance with respect to an adjustment parameter, and determines a first set of fitting coefficients of a first equation approximating the derived slopes in terms of a first variable representing each radius. The controller acquires write performance dependence on a variable representing each of multiple circumferential positions of the medium by measuring track average write performance with respect to the circumferential positions, and determines a second set of fitting coefficients to approximate by a periodic function the acquired dependence in terms of the first variable. The controller corrects a condition value representing the adjustment parameter by subtracting from the condition value an adjustment value obtained from functions calculated with the first and second sets of fitting coefficients.

Abstract: Apparatus and methods are disclosed for decoding data stored on a data storage medium. A disclosed decoding method and decoder include a radial incoherence (RI) detector that increases the probability of detecting RI and improves the decoding performance in terms of the bit error rate of the decoded signal. RI is detected by comparing an input signal to the decoder against a RI threshold value and generating a RI-type signal. The RI detector may include a filter for filtering out noise and error in the RI-type signal, an adaptive threshold unit that adjusts the RI threshold value based upon the RI-type signal, a transition-based threshold unit that adjusts the RI threshold value based upon each transition in the input signal, or a path-based threshold unit that adjusts the RI threshold value based upon a best surviving path corresponding to the input signal, in combination or alone.

Abstract: According to one embodiment, there is provided a method for determining whether a defect on a disk in an apparatus includes head is a recess or a protrusion. The method detects a first defect on the disk using a read element provided in the head. The method detects a second defect on the disk using a head disk interference sensor provided in the head. The method further determines whether a third defect is a recessed defect or a protruding defect based on a ratio between a first width of the first defect in a radial direction on the disk and a second width of the second defect in the radial direction of the disk. The third defect is identified based on the first defect and the second defect.

Abstract: A system and method for monitoring fly height between a magnetic recording medium and a transducing head. In a first exemplary embodiment, magnetic spacing change value is calculated using media noise on the recording medium (instead of prerecorded tones) to provide a broadband frequency distribution that results in improved Wallace equation accuracy. In a second exemplary embodiment, a magnetic spacing change value is acquired by any suitable method but is adjusted as necessary to reflect transducing head wear, thus providing a methodology for calculating changes in fly height by taking into account the signal loss that is attributable to wear. In this way, a basic understanding of the mechanism causing changes in magnetic spacing is achieved.

Abstract: According to an aspect of the present disclosure, a method includes: receiving a plurality of groups of one or more phase signals, each group of phase signals having a different phase relative to other groups of one or more phase signals; generating a plurality of interpolated phase shifted signals based on the plurality of groups of one or more phase signals, wherein the plurality of interpolated phase shifted signals do not have an associated common mode component; receiving data bits and precompensating each data bit in accordance with a given interpolated phase shifted signal; and selecting a precompensated data bit for output.

Abstract: The present application discloses a transducer head comprising a read element that reads data from a storage media and an asperity sensor that detects a dimension of an asperity on a surface of the storage media using a temperature change at the asperity sensor. The asperity may be one or both of a void in the surface of the storage media and a protrusion from the surface of the storage media.

Abstract: The present inventions are related to apparatuses and methods for detecting and classifying media defects. For example, an apparatus for classifying a media defect is disclosed including a DFT circuit operable to yield real and imaginary components of a signal derived from data read from a storage medium, a calculation circuit operable to calculate an amplitude and a phase of the signal based on the real and imaginary components, and a classifier operable to detect the media defect based on the amplitude and to classify the media defect based on the phase.

Abstract: Inter-track interference cancelation is disclosed, including: receiving an input sequence of samples associated with a track on magnetic storage; using a processor to generate inter-track interference (ITI) data associated with a first side track including by performing a correlation between the input sequence of samples and a sequence of data associated with the first side track.

Abstract: A method, apparatus, and system are provided for implementing magnetic defect classification using phase modulation for hard disk drives. A magnetic media readback signal of a hard disk drive is processed to identify predefined phase modulation (PM) characteristics to implement magnetic defect classification of magnetic media bump and pit defects.

Abstract: Methods are provided for pattern-dependent log likelihood ratio (LLR) manipulation of a hard disk drive detector output. Generally, by observing a pattern dependency of LLRs, various rules for LLR manipulation at the detector output are outlined. The rules may provide more reliable LLR values, such as by improving signal-to-noise ratio (SNR) of the hard disk drive detector output.