Abstract: An apparatus includes a bit patterned magnetic storage media, a write transducer positioned adjacent to the bit patterned magnetic storage media, a write driver coupled to the write transducer to deliver write pulses to the write transducer, an optical sensor for producing a bit pattern signal, and a timing recovery circuit for producing a synchronization signal in response to the bit pattern signal, wherein the timing of the write pulses is adjusted in response to the synchronization signal.

Abstract: Apparatus and methods are disclosed that adjust the phase of a read/write clock signal. The read/write clock signal may be used in a data storage apparatus to regulate reading/writing on a data storage media. An apparatus includes an adjustment circuit that adjusts phase of an edge of a read/write clock signal based on the timing of information that is read from a data storage media. Another apparatus includes a servo circuit and a read/write channel circuit. The servo circuit generates a leading edge transition of a servo gate signal in response to a signal indicating that a read/write transducer is approaching a start of a servo wedge. The read/write channel circuit generates a trailing edge transition of the servo gate signal in response to occurrence of a defined time delay following the transducer reading a servo address mark from the servo wedge.

Abstract: A method includes: producing a bit detection signal in response to a plurality of islands located in a plurality of zones of a bit patterned media, processing the bit detection signal to produce a synchronization signal, wherein the processing is dependent on characteristics of the islands in the zone containing the plurality of islands, and using the synchronization signal to control timing of writing to the bit patterned media. The synchronization signal can also be used to control timing of reading from the bit patterned media.

Abstract: Magnetic reference patterns may be generated on a disk or other magnetic media without the need for seed wedges. This involves writing a first magnetic reference pattern to the disk with a servo writer. The disk may then be transferred to a hard disk drive. Control circuitry within the hard disk drive may recognize the first magnetic reference pattern and then position a RW head within the hard disk drive based on the first magnetic reference pattern. As the RW drive is accurately positioned based on the first magnetic reference pattern a second magnetic reference pattern may be written to the disk using the RW head. The RW head location is determined based on the velocity and phase between the read-write head and spiral sync marks contained within the first magnetic reference pattern.

Abstract: A method is disclosed of writing product servo sectors to a disk of a disk drive to define a plurality of product servo wedges, the disk comprising a plurality of spiral tracks. The spiral tracks are spaced apart circumferentially by a substantially equal spacing, and the number of spiral tracks equals a non-integer multiple of product servo wedges. The head internal to the disk drive is used to read the spiral tracks to generate a read signal, and the sync marks are detected from the read signal to generate a sync mark detect signal. A timing recovery measurement is generated in response to the sync mark detect signal, and a frequency control signal is generated in response to the timing recovery measurement. A servo write clock is generated in response to the frequency control signal which is used to write the product servo sectors to the disk.

Abstract: Determining timing for bits in sampled data includes determining a bit error in the sampled data, determining a phase error in the sampled data, determining a frequency error of the sampled data based on the bit error and based on the phase error, and determining the timing for bits in the sampled data based on the determined frequency error.

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

Abstract: According to one embodiment, a servo information writing method for use in a disk drive, for recording the servo information, forming a continuous servo track such as a spiral track. In this servo information writing method, the head is stopped when a write error is detected while the servo information is being written, and the head is then moved again at a constant speed and starts writing the servo information again, at the position where the write error has occurred.

Abstract: Methods in accordance with the present invention can include determining a plurality of sets of write pre-compensation parameters. At baseline conditions, the hard disk drive can apply a first current and write pre-compensation parameters can be tuned to generate a desired write current waveform that can be applied to the read/write head to generate a magnetic field to define magnetization on the magnetic media. The hard disk drive can then apply a second current and write pre-compensation parameters can be tuned to generate the desired write current waveforms. A plurality of write pre-compensation parameters can then be generated based on the results for a plurality of corresponding temperatures and/or temperature ranges.

Abstract: The method and architecture improve the robustness of a synchronization system through a minimum latency loop, for Hard Disk Drives (HDD), for example, wherein synchronous detection processing is performed for timing recovering of a correct sampling phase and frequency and by a first acquisition step of a known preamble signal pattern, for generating a timing periodic signal, followed by a second tracking step, for recovering phase, frequency and gain sampling errors of the synchronization signal including a header followed by an unknown data content. Advantageously, a feedback loop including a numeric preamble generator (NPG) is provided for obtaining a reduced latency in the acquisition phase. The NPG stores preamble values for different phase offset.

Abstract: The present invention provides a read channel and a drive capable of suppressing deterioration in performance of a PLL and a Viterbi decoder by using a DC component eliminating means capable of higher-speed operation than hitherto. The location of an edge is determined by using differential of a read signal, and a DC component is detected from the midpoint level of the edge. Detection of a pseudo-edge due to a long mark or space signal is prevented by limiting the absolute value of a maximum or minimum of a differential coefficient when the location of the edge is determined from the differential coefficient of the read signal. Internal operation of a DC component detector is controlled according to the state of the PLL and the magnitude of the DC component.

Abstract: A patterned disk medium includes a disk-shaped flat substrate including a first surface and a second surface located an opposite side of the first surface. First servo pattern areas including portions provided with magnetic members and portions provided with no magnetic members are provided on the first surface. Second servo pattern areas including portions provided with magnetic members and portions provided with no magnetic members are provided on the second surface. The magnetic members of the first and second servo pattern areas are magnetized in a direction perpendicular to the first and second surfaces. The magnetic polarity of the surfaces of the magnetic members of the second pattern areas differs from that of the surfaces of the magnetic members of the first pattern areas.

Abstract: Provided is a method and apparatus for adaptively controlling the timing of servo pulses in a disk drive in consideration of the amount of spindle jitter generated when a disk rotation speed is changed. The method of controlling the timing of a sector pulse for write operation includes: measuring a spindle jitter value in a data write mode; generating a timing correction value of a sector pulse, which indicates a position of a sector where data is written, according to the measured spindle jitter value; and generating a sector pulse by reflecting the timing correction value of the sector pulse.

Abstract: A method of writing spiral tracks on a disk of a disk drive is disclosed. The disk drive comprises control circuitry and a head disk assembly (HDA) comprising the disk, an actuator arm, a head coupled to a distal end of the actuator arm, and a voice coil motor for rotating the actuator arm about a pivot to position the head radially over the disk. A write clock is synchronized to the rotation of the disk, and a plurality of spiral tracks are written on the disk at a predetermined circular location determined from the write clock. Each spiral track comprises a high frequency signal interrupted at a predetermined interval by a multi-bit sync mark, and each multi-bit sync mark comprises a plurality of bits.

Abstract: A calculating unit calculates an interval time from a detection of a servo sync mark until a detection of an adjacent servo sync mark, for all servo sync marks on a track of a disk-shaped recording medium. A measuring unit measures, based on the calculated interval time, a deviation amount between a link interval time that represents the interval time between a servo sync mark recorded first and a servo sync mark recorded last and an ideal interval time that represents the link interval time when it is assumed that all the servo sync marks on the track are written at equal intervals.

Abstract: Provided is a read channel, storage drive, and method to process signals read from a storage medium. At least one data channel including an interpolator and equalizer and a servo channel includes an interpolator. A timing recovery function processes a timing error from the interpolator in the servo channel to calculate interpolation timing information used by the interpolator to interpolate a servo channel signal. A path is coupled to the timing recovery function and the interpolator in the at least one data channel to communicate the interpolation timing information to the interpolator in the at least one data channel. The interpolator in the at least one data channel is configured to use the interpolation timing information to interpolate an asynchronous data channel signal.

Abstract: A method and apparatus is disclosed for adjusting the track density by changing the slope of spiral tracks used to servo write a disk drive. A target track density is established for a disk surface, and a plurality of spiral tracks are written to the disk surface in response to the target track density. Each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark, and a slope of the spiral tracks is selected in response to the target track density. The head internal to the disk drive is used to read the spiral tracks in order to write product servo sectors to the disk to define a plurality of data tracks, wherein the slope of the spiral tracks determines the density of the data tracks.

Abstract: A signal processing device having a feature of analog-to-digital converting a burst signal has a feature of selecting data bus to notify a disk control device 2 of a conversion result via an NRZ data bus. The disk control device 2 includes means for storing the result of the analog-to-digital conversion of said servo positional signal. The positional signal of a head of the disk device is digitalized in an R/W channel. Sampling for digital conversion is performed in only a window which is defined only in the vicinity of peaks of the positional signal. The values of peaks which are obtained by sampling are averaged by an averaging circuit. This enables the influence of noise occurred outside of the window to be eliminated. Although the noise in the window is sampled, its adverse influence is suppressed by the averaging processing.

Abstract: A servo writer that writes servo information onto a disk of a hard disk drive. The writing of the servo can be synchronized by a clock track that contains a clock read back signal. The clock read back signal is differentiated by a differentiator circuit. A clamping circuit clamps the clock read back signal to minimize signal ringing, undershoot and overshoot phenomena in the signal.

Abstract: A servo signal inspection device and a method for detecting servo signal are provided which can measure and evaluate quality of the servo signal on a magnetic tape with a sufficient resolution. The device includes a servo signal inspecting head, a peak detecting means, a time interval measuring means and an inspection means, wherein a period T [s] of a standard clock signal used in the time interval measuring means and a running speed v [m/s] of the magnetic tape at the servo signal inspecting head satisfy the following relationship: T×v<80 nm.

Abstract: Various systems and methods for accessing data via a variable polarity head assembly are disclosed herein. As one example, a method for accessing data is disclosed that includes receiving a data set, and sampling the data set using positive synchronization to create one data set and negative synchronization to create another data set. A respective sync mark is identified in each of the data sets, and the identified sync marks are compared. Based at least in part on the comparison of the sync marks, a polarity of the data set is identified. Based on the determined polarity of the data set, the data set may be delivered in a known polarity.

Abstract: An adaptive signal equalizer with a feedforward filter in which the feedback error signal and corresponding incoming data signal are dynamically aligned in time using signal interpolation, and further, to control the precursor/postcursor filter taps configuration, thereby producing more adaptive filter tap coefficient signals for significantly improved and robust signal equalization.

Abstract: A servo control system includes a peak detection module that detects peak times of spiral signals generated by reading spirals prewritten on a magnetic medium. The servo control system includes a control module that determines positions of the spirals based on the peak times, stores the positions of the spirals, seeks and tracks the spirals using the positions, and writes servo on the magnetic medium based on the positions of the spirals.

Abstract: One or more methods and systems are presented for performing gain and timing acquisition of data read from one or more data sectors of a hard disk drive. The gain and timing information may be used to synchronize a read channel receiver of the hard disk drive to the data read from the data sector(s). In a representative embodiment, the one or more methods comprises determining one or more frequency and phase offsets using one or more preambles of one or more data sectors residing in a hard disk drive. In a representative embodiment, the gain of the one or more preambles may be determined. In another representative embodiment, the one or more systems used to determine one or more phase and frequency offsets, and amplitudes, comprise hardware and/or software capable of utilizing a sequence of consecutive samples provided by one or more preambles of one or more data sectors.

Abstract: A hard disk drive system includes a control module that generates a phase offset signal for a repeatable run out (RRO) field of a servo wedge based on an RRO phase of the RRO field and a data phase of data in at least one other servo wedge field of a previously written wedge. A read/write channel module adjusts a clock phase based on the phase offset signal.

Abstract: The present invention provides a frequency synthesizer capable of switching an oscillation frequency band while maintaining a lock state realized with a small-scale and low-current-consumption circuit configuration, and an oscillation control method of the frequency synthesizer.

Abstract: A digital PLL system includes a first multiplier coupled to a phase difference signal for multiplying the phase difference signal by a first gain factor; a second multiplier coupled to the phase difference signal for multiplying the phase difference signal by a second gain factor; a digital loop filter coupled to the first multiplier and the second multiplier for providing an integral signal and a proportional signal and for generating a control signal according to the integral signal and the proportional signal; and an auto-gain control (AGC) unit coupled to the first multiplier, the second multiplier, and the digital loop filter. The AGC unit further comprises a first control unit for updating the first gain factor according to the integral signal; and a second control unit for updating the second gain factor according to the proportional signal.

Abstract: In one embodiment, a surface analyzer system comprises a radiation targeting assembly to target radiation onto a surface, a reflected radiation collecting assembly that collects radiation reflected from the surface, and a signal processing module. The signal processing module generates an image of magnetic characteristics of the magnetic disk, wherein the image comprises a plurality of servo sector arcs, locates a sample of points on a plurality of the servo sector arcs, fits a circle to the sample of points on each of the plurality of servo sector arcs, and determines at least one pivot-to-gap measurement from the radius of the circles.

Abstract: A read channel and method using that read channel are disclosed. The read channel comprises an analog to digital converter which asynchronously samples at a fixed rate an analog signal formed by reading a data track, where that data track was written to a data storage medium at a symbol rate and an interpolator interconnected with the analog to digital converter. The read channel further comprises a fractionally-spaced equalizer, where the interpolator provides an interpolated signal to the fractionally-spaced equalizer at an interpolation rate, where that interpolation rate is greater than the symbol rate. The fractionally-spaced equalizer forms a synchronous equalized signal. The read channel further comprises a gain control module interconnected with the fractionally-spaced equalizer, and a sequence detector interconnected with the gain control module.

Abstract: According to one embodiment, there is to provide a servo write method of writing a multi-spiral servo pattern to a disk medium, the method including a process of writing a spiral index pattern to the disk medium, the spiral index pattern being a spiral pattern including the same region as that of a servo burst signal included in the spiral servo pattern and a region that allows the spiral index pattern to be distinguished from the spiral servo pattern, the spiral index pattern being used as a reference for a write start.

Abstract: A method of servo writing a disk of a disk drive is disclosed. The disk comprises a plurality of spiral tracks, wherein each spiral track comprises a high frequency signal interrupted periodically by a sync mark. A timing recovery measurement is generated in response to the sync marks, wherein the timing recovery measurement comprises a sinusoidal component. A timing compensation value is generated in response to the sync marks which estimates the sinusoidal component in the timing recovery measurement. A frequency control signal is generated in response to the timing recovery measurement and the timing compensation value, a servo write clock is generated in response to the frequency control signal, and the servo write clock and the head internal to the disk drive are used to write the product servo sectors to the disk.

Abstract: A method of writing product servo sectors to a disk of a disk drive is disclosed. The disk comprises a plurality of spiral tracks, wherein each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark. The read signal from the head is processed to detect a plurality of the sync marks in a spiral track crossing. A timing recovery measurement is generated in response to a selected one of the sync marks based on reliability metrics, wherein a servo write clock is synchronized in response to the timing recovery measurement. The read signal representing the high frequency signal in the spiral track crossing is processed to generate a position error signal (PES) used to maintain the head along a substantially circular target path while using the servo write clock to write product servo sectors along the circular target path.

Abstract: Bit and byte synchronization for sampling and decoding a data string is provided a single data field u. The data string x has pre-pended to it a short string of 1s (ones), followed by u to yield a string y= . . . 1111, u, x. The string is pre-coded by convolution with 1/(1?D2). PRML-sampling of y starts at an initial phase, and vectors are obtained from that string by sampling at pre-selected phases following the initial sampling point. The vectors of y are compared with vectors corresponding to PRML samples of an initial set of bits in u obtained at predetermined phases. The pair of y, u vectors exhibiting the minimum Euclidian distance yields a sampling correction value by which the initial sampling phase is corrected and a new initial sampling point preceding x is determined. Here, bit and byte synchronization have been achieved and sampling of x proceeds at the corrected phase, from the new initial sampling point.

Abstract: Various embodiments of the present invention are generally directed to processing servo data on a storage surface by detecting a time difference between consecutive read signal envelopes from spiral servo information on the surface.

Abstract: A servo circuit includes a servo channel and a processor. The servo channel recovers servo data from servo wedges that identify respective data sectors on a data-storage disk. The processor detects one of the servo wedges on spin up of the disk, i.e., while the disk is attaining or after the disk attains an operating speed. By detecting a servo wedge instead of a spin-up wedge to determine an initial head position on disk spin up, such a servo circuit allows one to increase the disk's storage capacity by reducing the number of, or altogether eliminating, spin-up servo wedges from the disk.

Abstract: Embodiments of the present invention pertain to handling synchronization errors potentially experienced by a storage device. According to one embodiment, a system for handling synchronization errors potentially experienced by a storage device includes a joint detector and a decoder. The joint detector detects transmitted data. The joint detector also detects timing errors that potentially result from the transmission of the data. The joint detector communicates information about the transmitted data and the timing errors with the decoder iteratively in a loop to reduce the amount of the transmitted data that is lost.

Abstract: A synchronous read channel having a single chip integrated circuit digital portion which provides digital gain control, timing recovery, equalization, digital peak detection, sequence detection, RLL(l,7) encoding and decoding, error-tolerant synchronization and channel quality measurement is disclosed. The integrated circuit accommodates both center sampling and side sampling, and has a high degree of programmability of various pulse shaping and recovery parameters and the ability to provide decoded data using sequence detection or digital peak detection. These characteristics, error-tolerant sync mark detection, and the ability to recover data when the sync mark is obliterated allow a wide variety of retry and recovery strategies to maximize the possibility of data recovery.

Abstract: Disclosed is a rotating media storage device (RMSD) that has at least one calibration track with unique calibration servo synch marks (SSMcs). The RMSD includes a disk that comprises a plurality of tracks including a calibration track having a plurality of normal servo wedges distributed around the calibration track. At least one of the normal servo wedges includes a normal servo synch mark (SSMN). Further, at least one calibration servo wedge is distributed between a pair of normal servo wedges. The calibration servo wedge includes a calibration servo synch mark (SSMC). The calibration SSMC includes a pattern that is different than the pattern associated with the normal SSMN.

Abstract: A method leverages knowledge of the actual or ideal bit sequence to improve the performance of any sequence detector. This improved performance results by constraining the sequence detector when the sequence detector has knowledge of known patterns within the sample sequence. Embodiments may control or limit the effects of ISI on a readback signal in order to allow higher storage within physical media such as that of a HDD. This method involves reading an analog waveform from the physical media. The phase of this analog waveform is determined and it is sampled at regular intervals using a timing recovery scheme. This sample sequence is equalized (filtered) and sent to a sequence detector which will compare the received sequence to all possible transmitted sequences, generating a path through a trellis that represents the estimated sequence. That trellis path may pass through known states at certain times. This knowledge makes it possible to remove some of the paths under consideration.

Abstract: Method and apparatus for processing transmitted data. A sampling circuit preferably performs lossy sampling of a continuous signal to provide a corresponding sequence of discrete samples at a sampling rate less than a Nyquist rate of the continuous signal. A processing circuit reconstructs an informational content of the continuous signal from the discrete samples, and operates to periodically insert additional samples into the sequence, which preferably increases an effective rate of said sampling to match or exceed the Nyquist rate. Preferably, the lossy discrete samples are temporarily stored in a memory space prior to reconstruction by the processing circuit. The sampling circuit preferably comprises an analog-to-digital converter (ADC) of an analog front end (AFE). The processing circuit preferably comprises a digital back end (DBE) employing partial-response, maximum-likelihood (PRML) detection. The additional samples are preferably provided by an iterative timing recovery (ITR) block of the DBE.

Abstract: A reproducing apparatus, in which a reproduced information signal is equalized by an equalizer, includes a detecting circuit for detecting a digital signal from the reproduced information signal, and a controller for controlling an equalizing characteristic of the equalizer according to the reproduced information signal to be inputted to the detecting circuit and a detection result of the detecting circuit.

Abstract: Apparatuses and methods for detecting reference marks on magnetic data storage mediums are described herein. In one variation, the apparatus comprises a magnetic servo position demodulator operable to extract information from the magnetic data storage medium utilizing Partial Response/Maximum Likelihood (PRML) technique. Synchronization marks stored within the PRML channel is then detected utilizing a digital filter. For each of the detected synchronization mark, a further refined position of the synchronization mark can be determined utilizing a mathematical prediction model.

Abstract: A read channel equalizer of a magnetic tape drive which equalizes digitally sampled magnetic signals detected by a read head is dynamically adapted. A detector of equalizer dynamic adaptation logic compares equalizer output signals to desired values that are based on the decoding scheme (such as +2, 0 and ?2 for PR4) to sense equalizer output signals that are offset from at least one desired value, and signals the fact of each offset and it polarity as amplitude independent error signals. The signaled sensed amplitude independent error signals are fed back to adjustable taps of the equalizer. The simplified error signals thus avoid complex calculations of waveform errors, such as least mean square calculations. The error signals may be weighted and may be adjusted to align synchronously provided error signals with asynchronous taps of the equalizer.

Abstract: A computer system is provided, the computer system having a chassis that encloses a processor and a system memory. The computer system further comprises a reader/writer selectively positionable between a storage position inside the chassis and an operational position outside the chassis.

Abstract: Timing recovery and synchronization for data communication is utilized. A pilot sequence of signals can be selected to improve recovery of a phase offset and a frequency offset in a communication system. Sampling instances can further be adjusted based on pilot sequences within a user data portion.

Abstract: Various systems and methods for providing head location feedback are disclosed herein. For example, one system includes an interface circuit that is operable to receive an information stream retrieved from a magnetic storage medium. The magnetic storage medium includes one or more tracks that each include a plurality of sectors. The sectors include burst information that can be utilized to aid in positioning a read/write head assembly over a magnetic storage medium. The systems further include a multiple sector error detection circuit. The multiple sector error correction circuit is operable to phase align samples of a burst obtained from one sector with samples of a burst obtained from another sector. An amplitude of each of the bursts is determined, and the determined amplitudes are combined. The combined amplitudes correspond to a position error of the read/write head assembly relative to the magnetic storage medium.

Abstract: Aimed at is to match a timing of a clock signal with a magnetic dot of a patterned medium. A point at which an amplitude of a reproduction waveform becomes zero or a point at which an amplitude of a magnetic signal changes from the positive to negative or from the negative to positive is detected, and a zero level detection signal or zero-cross detection signal is output to a clock generation circuit which then synchronizes a clock signal with the zero level detection signal or zero-cross detection signal. This enables a matching of the clock signal with a magnetic dot.

Abstract: Aimed at is to match a timing of a clock signal with a magnetic dot of a patterned medium. A magnetic part arraying magnetic dots for recording a magnetic signal at certain intervals and a nonmagnetic part not recording a magnetic signal are featured in the patterned medium. A position of the nonmagnetic part not recording a magnetic signal is detected by a magnetic head and a clock signal is synchronized with a detection signal of the nonmagnetic part.

Abstract: An apparatus comprises a data storage medium having a plurality of servo sectors and a plurality of data sectors, wherein each of the servo sectors includes a phase locked loop field and a track identification field, a controller for controlling the position of a recording head with respect to the data storage medium, and a servo demodulator for recovering timing information from both the phase locked loop field and the track identification field, and for producing a timing estimate. The method performed by the apparatus is also included.

Abstract: A disc drive system, such as a magnetic or optical recording and/or playback system, for low-data rate applications implements one or more circuit operations, such as read signal detection and related servo functions, as software-based digital signal processing steps in a dedicated software-based processor. The drive system incorporates increased buffering, modified input sample processing techniques, multiplexing of processing functions, and modified automatic gain control techniques to allow circuit operations to be performed with software-based digital signal processing techniques.