Abstract: A recording system, such as a magnetic or optical recording system, employs an address mark (AM) detector that searches for an address mark pattern that is augmented by one or more bits of a preamble field so that a false detection rate is reduced. In one case, the address mark includes L bits, and the AM detector compares i) the input detected bits with ii) a SAM pattern of L bits augmented with m bits of the preamble to detect the SAM. In another case, the address mark includes less than L bits (e.g., L?k bits), and the AM detector compares i) the input detected bits with ii) a SAM bit-pattern of (L?k) bits augmented with m bits of the preamble to detect the SAM.

Abstract: A method of determining a correction factor for a voice coil motor of a disk drive device is performed by driving a relatively low current through the voice coil motor during a seek operation. Actuator velocity is then measured. A correction factor is calculated as a function of the actuator velocity to allow estimation of velocity as a function of back EMF.

Abstract: A magnetic recording disk drive has disks with identical pre-patterned servo patterns on their front and back surfaces and a servo control system for positioning the read/write heads using the servo signals from the identical servo patterns. The servo sectors on the two disk surfaces form identical patterns of angularly spaced arcuate-shaped lines that extend generally radially across the data tracks. The arcuate-shaped lines on one surface, the front surface, generally replicate the path of the recording head as it is moved across the data tracks by a rotary actuator, so that there is a constant sampling rate of the servo sectors on the front surface regardless of radial position of the head. However, the arcuate-shaped lines on the other surface, the back surface, do not replicate the path of the recording head so the servo sampling rate is not constant but varies with radial position of the head.

Abstract: Provided is a hard disc drive controlling method, and more particularly, a method of controlling track seek in a hard disc drive (HDD) provided against a shift between discs, and a computer readable recording medium having embodied thereon a computer program for the method. The method of controlling track seek in a HDD, including disc switching, includes: head switching to a head corresponding to a disc having a target track; calculating track seek length by comparing the previous target track address and the current target track address; determining whether or not the track seek length is shorter than the limit seek length set by considering a shift of a disc; if the track seek length is shorter than the limit seek length, reading the track address of a track on which the head is put on the switched disc, and by referring to the read track address and the target track address, determining track seek length and a seek profile thereof; and performing track seek according to the determined seek profile.

Abstract: A disk drive includes a head and a disk, spiral patterns are located on the disk, and the disk drive self-writes servo patterns on the disk using the spiral patterns as a reference for servoing the head. In an embodiment, the disk drive uses preliminary servo patterns to determine repeatable runout of the spiral patterns. In another embodiment, the disk drive reads each spiral pattern with multiple timing windows.

Abstract: A method and apparatus to safely repress disturbances from being applied to a system from the surroundings in which the system is used. The method of adaptively repressing disturbances includes estimating frequency components of a disturbance applied to a system in a user environment; and optimizing parameter values determining characteristics of a disturbance compensating servo control loop including a disturbance observer, based on the estimated frequency components of the disturbance.

Abstract: A hard disk drive with a circuit that provides a current to a voice coil motor to move a head over a disk in a seek routine. The disk has track boundaries with discontinuities in track addresses. The circuit includes a state estimator that predicts a next state of the head. The state estimator sets an estimation error to zero when the head is over one of the track boundaries. The estimator then computes a predicted position that is used in a feed forward servo loop to generate a drive current. The drive current is provided to the voice coil motor to move the head across the disk.

Abstract: A method of determining a correction factor for a voice coil motor of a disk drive device is performed by driving a relatively low current through the voice coil motor during a seek operation. Actuator velocity is then measured. A correction factor is calculated as a function of the actuator velocity to allow estimation of velocity as a function of back EMF.

Abstract: A method of controlling a disk drive is disclosed that is capable of precise and real-time detection of an abnormal floating height of a magnetic head over an entire area of a magnetic disk. The method of controlling the disk drive includes the steps of: calculating a servo gain difference between a servo gain value obtained from a servo frame of the disk drive and a normal servo gain value recorded in the servo frame, the normal servo gain value being a servo gain value when a magnetic head flies normally relative to a magnetic disk; and forbidding the magnetic head writing data into the magnetic disk when the servo gain difference is equal to or greater than a predetermined value.

Abstract: A magnetic recording medium having a magnetic layer containing magnetic powder provided on a support is disclosed. The magnetic layer possesses a servo band in which a servo signal for controlling tracking of a magnetic head, and a data band on which a data is recorded. The servo signal is magnetized and recorded on the servo band, having been magnetized in one direction of the track direction thereof, in the direction other than the one direction. The thickness of the magnetic layer ranging from 10 to 180 ?m, and variation [standard deviation of Mrt] of the product [Mrt] of the residual magnetism by the thickness of the magnetic field being not more than 30%.

Abstract: A data storage system in which multiple readback signals are resolved is provided. The data storage system includes a data storage medium configured to store servo marks and data marks. The data storage medium has tracks that are divided into sectors. An array of heads is configured to interact with the data storage medium. A demodulation circuit receives servo signals obtained by at least some heads of the array of heads and computes a resultant servo signal, which is used to adjust a position of the array of heads over the storage medium.

Abstract: Disclosed is a disk drive to characterize misaligned servo wedges. A disk of the disk drive includes a plurality of circumferential tracks, in which, each track includes a plurality of servo wedges spaced sequentially around the circumference of the track wherein the servo wedges may be misaligned relative to the head of the disk drive that moves about a pivot. A servo controller is used to characterize the misaligned servo wedges relative to the head during a seek operation by implementing the following operations: commanding the head to perform a seek operation from a starting track to an ending track; obtaining samples of wedge-to-wedge time (WTWT) values corresponding to time intervals between identified servo wedges for sampled tracks traversed during the seek operation; calculating WTWT variations for each sample; and calculating a calibrated misalignment value for each sample based upon WTWT variations.

Abstract: A disk drive includes a disk for storing information, a head with a transducer that writes data to and reads data from the disk, and an AC power source. The head is suspended adjacent to the disk and a flying height gap exists at the head/disk interface. The AC power source generates an AC exciter signal across the flying height gap that discharges electrostatic charge at the head/disk interface. The head/disk capacitance can be measured based on the AC exciter signal to sense the flying height. The AC exciter signal can also alter an attraction force between the head and the disk and thus control flying height. The AC exciter signal can also be based on a flying height signal representative of the head/disk capacitance and thus the flying height.

Abstract: A method and apparatus for generating an index location from a spin motor of a disk drive are disclosed. A disk drive includes a motor having a plurality of commutation states, wherein changes in commutation states are controlled by an FCOM signal having FCOM pulses. Ideally, when the motor is spinning at a constant speed, the time between FCOM pulses is constant. However, the inventor of the present invention has recognized that, in practice, the time between FCOM pulses, when measured more closely, is not constant due to mechanical tolerances in the motor. Accordingly, the inventor has determined that the non-constant times between FCOM pulses can be advantageously used to generate a spin motor index in a disk drive. Once obtained, the spin motor index may advantageously be used for a number of purposes.

Abstract: On the basis of the position of a first target track specified by a command from a host, a CPU calculates a first offset value reflecting a track pitch that enables the adverse effects of crosstalk to be suppressed. The first offset value indicates an offset of a target position at which a head is to be actually positioned from a predetermined position on the first target track. The CPU determines a second target track, to which the target position belongs, and a second offset value on the basis of the position of the first target track and the calculated first offset value. The second offset value indicates an offset of the target position from the predetermined position on the second target track. The CPU positions the head at the target position on the determined second target track on the basis of the determined second target track position and second offset value.

Abstract: A magnetic data embedding system (or disk servo writer) includes a stack with a master disk (3) and a plurality of magnetic disks (4) mounted on a shaft of a spindle motor (6), and a rotary positioner (11) which integrally holds one or more read-only heads (71 to 74) for reading the master disk and a plurality of groups of servo heads (101 to 104) and which simultaneously turns both of the kinds of heads. The groups of servo heads have access to the top and bottom sides of the magnetic disks. The servo heads are made carry out writing to the same (top or bottom) side of each of the disks in parallel, within assigned track ranges for the respective servo heads.

Abstract: Systems are provided for improving servo-demodulation robustness. Multiple occurrences of a SAM pattern are searched for in a single servo wedge. Each detection of the SAM pattern in the servo wedge is charactered as a good SAM detection or a bad SAM detection. If more than one detection of the SAM pattern in the servo wedge are characterized as good SAM detections, one of the detections is selected as the best good SAM detection. Further servo functions can then be performed based on the best good SAM detection.

Abstract: A disk device and a disk medium are disclosed in which a plurality of servo cylinders on the surface of at least one disk are divided into several areas, and a different servo signal frequency is set and recorded for each of the areas. The servo cylinders are divided into predetermined areas, and a different servo signal frequency for each of the areas is set so that the recording density of the servo signal recorded in the disk can be set so as to allow the servo signal demodulation characteristic to be included in a relatively superior range. In the disk device, the boundary between the area of a first servo signal frequency and the area of a second servo signal frequency adjoining the first servo signal frequency area is preferably formed with an area in which a servo signal pattern written with the first servo signal frequency and a servo signal pattern written with the second servo signal frequency are arranged on the same servo cylinders.

Abstract: A position information signal pattern is recorded into a recording medium. The position information signal pattern is configured by arranging graphics having a circular shape, a rectangular shape or the like surrounded by a certain closed curve as pattern elements on a plane, and arranging the pattern elements in circumferential and radial directions of a disc so that a phase and a head position establish a proportional relationship in two or more frequency components of a reproduced signal. Position signals of the two frequency components included in the reproduced signal from the position information signal pattern are obtained, and the two position signals are added up with a certain ratio so that a position signal without error is obtained.

Abstract: Systems are provided for improving servo-demodulation robustness. The SAM pattern is searched for in a servo wedge. If the SAM pattern is detected in the first servo wedge, a determination is made whether to characterize the detection of the SAM pattern as either a good SAM detection or a bad SAM detection. If the detection of the SAM pattern is characterized as a good SAM detection, one or more channel control values (e.g., servo AGC and/or PLL values) associated with the first servo wedge are used as (or to predict) starting values when beginning to read a next servo wedge. However, if the SAM pattern is not detected, or a detection is characterized as bad, one or more previously stored or predicted channel control values are used as (or to predict) starting values when beginning to read the next servo wedge.

Abstract: Methods are provided for improving servo-demodulation robustness. A SAM pattern is searched for in a servo wedge. If the SAM pattern is detected in the first servo wedge, a determination is made whether to characterize the detection of the SAM pattern as either a good SAM detection or a bad SAM detection. If the detection of the SAM pattern is characterized as a good SAM detection, at least one channel control value (e.g., servo AGC and/or PLL values) associated with the first servo wedge is used as a starting channel control value (or to predict a starting channel control value) when beginning to read a next servo wedge. However, if the SAM pattern is not detected, or a SAM detection is characterized as bad, at least one previously stored channel control value is used as a starting channel control value (or to predict a starting channel control value) when beginning to read the next servo wedge.

Abstract: Magnetic transfer can be performed with high reliability by shortening the magnetic transit interval of servo address information, that is, a section in which “0” or “1” continues. An area for registering information indicating a start position of data inversion or non-inversion of the servo address information is formed between a servo detection pattern and servo address information of the servo signal. When a continuing data section exceeds a predetermined section in a data sequence of the servo address information, the data at the subsequent portion to the exceeding position are inverted or non-inverted, and the exceeding position is registered as a start position for inversion or non-inversion in the area.

Abstract: A data recording system uses a recording medium in which the tracks have pseudo-noise (PN) sequences with good autocorrelation properties as servo information for controlling the position of the recording head. A first set of alternating tracks uses a leading pseudo-random binary sequence (PRBS), which is a PN sequence with good autocorrelation properties, and a following PRBS that is cyclically shifted from the leading PRBS. A second set of alternating tracks interleaved with the first set also has a leading PRBS and a following PRBS that is cyclically shifted from the leading PRBS, but the leading PRBS in each of the tracks in the second set is offset along-the-track from the leading PRBS in the tracks of the first set. The head positioning control system uses the leading PRBS to generate a servo timing mark (STM), the cyclic shift to generate track identification (TID), and the following PRBS from adjacent tracks to generate the head position error signal (PES).

Abstract: Methods are provided for limiting channel control values, such as servo automatic gain control (AGC) values and/or servo phase lock loop (PLL) values, within respective desired ranges. Keeping such values within desired ranges improves servo demodulation robustness.

Abstract: Systems are provided for limiting channel control values, such as servo automatic gain control (AGC) values and/or servo phase lock loop (PLL) values, within respective desired ranges. Keeping such values within desired ranges improves servo demodulation robustness.

Abstract: A disk drive is disclosed which pre-computes first seek parameters to seek to a continuation track storing read-ahead data, and second seek parameters to seek to a target track of a next command. An abort window is also computed for aborting a read-ahead operation early in order to seek to the target track of the next command. If the head enters the abort window, the disk drive is programmed with the second seek parameters to seek to the target track of the next command. If the read-ahead operation requires a seek to the continuation track prior to the head entering the abort window, the disk drive is programmed with the first seek parameters to seek to the continuation track.

Abstract: A method and apparatus for reducing the servo position error signal non-linearity during self-servo writing irrespective of the head width is disclosed. Write current of each head is modified based upon the head width. The write width for all heads is measured and a write current for each head in a disk drive is adjusted toward a predetermined level. A mean track propagation width for the disk drive is determined, wherein the predetermined level establishes the determined mean track propagation. A mean head width is determined and the write current for each head is adjusted by applying a higher write current to heads smaller than the mean head width and a lower write current to heads wider than the mean head width. Optimal performance is achieved using the adjusted write currents. The measuring of the head width is repeated and the write current is adjusted until a track propagation for the disk drive meets a predetermined criteria.

Abstract: Rotary positioners integrally and pivotally stack a read magnetic head for reading a master disk and servo heads for writing to each surface of magnetic disks, the master disk and magnetic disks being stacked on a shaft of a spindle motor. Every surface of every magnetic disk is written by the servo heads in parallel while sharing a range of tracks. Simultaneously with the writing, checking magnetic heads stacked on a checking-dedicated rotary positioner read written data on the master disk and on each surface of the magnetic disks. A comparison logic circuit compares the read data from the magnetic disk surfaces with the data from the master disk. If an inconsistency is found, the contents of the master disk are overwritten on the corresponding magnetic disk surface through a correction servo pattern generator by the checking magnetic head.

Abstract: The position error signal (PES), representing relative position regarding position information (RRO) previously recorded on a magnetic disk and the magnetic head, is averaged in each servo sector by an averaging unit, and a control input is obtained based on the PES by a phase compensator and the control input undergoes an averaging process in each servo sector by another averaging unit. Convolution integration with respect to the signal data processed by those averaging units is carried out by using a transfer characteristic formed by adding 1 to an open-loop transfer characteristic, which is determined by a magnetic head actuator model and a servo control circuit, to obtain a synchronous vibration estimate. This estimate undergoes a high-pass filtering process of a zero phase error characteristic by the filter unit to remove the vibration component of low frequency band and to thereby obtain a synchronous vibration learned value with high precision.

Abstract: A disk storage apparatus includes: an actuator positioning a head with respect to a disk; a drive device driving the actuator; a voltage detection device detecting a voltage signal induced in driving the actuator; a disturbance estimation unit estimating the magnitude of load disturbance exerted on the head from a drive signal and the voltage signal, and outputting a disturbance estimation signal; a filter unit cutting off a high frequency component of the disturbance estimation signal, and outputting a filter signal; a position detection unit producing a position error signal corresponding to a current position of the head; a position control unit producing a position control signal based on the position error signal; and a correction unit outputting the drive signal based on the filter signal and the position control signal, and the apparatus controls stable positioning of the head against a resistance value fluctuation of a drive coil of the actuator and a resistance value change.

Abstract: In a first mode, an R/W channel starts to monitor read information to thereby detect a servo mark contained in servo information, each time a servo controller generates a servo gate pulse. Upon detecting the servo mark, the R/W channel detects, from the read information, position information contained in the servo information and following the servo mark, at a timing determined by the detection timing of the servo mark. When the first mode has been switched to a second mode, the R/W channel detects the servo mark and position information using the synchronous method.

Abstract: Methods are provided for improving servo-demodulation robustness. SAM pattern detections are characterized as either good SAM detections or bad SAM detections. Further servo functions are then based on whether the detection of the SAM pattern in a servo wedge was characterized as a good SAM detection or characterized as a bad SAM detection.

Abstract: The invention relates to a method and a system for testing a head gimbal assembly, the system comprising means (54) for inputting a control command to perform a long seek operation, means (55) for measuring the mechanical frequency response of the head gimbal assembly to the long seek operation, and means (57) for comparing the frequency response to a master frequency response (58).

Abstract: There is disclosed a disk drive using a disk medium in which a non-servo range exists. In order to position a head at a target track, a CPU executes a seek operation by normal velocity control using servo data. At this positioning, when the head passes the non-servo range from which no servo data can be obtained, the CPU executes a seek operation by special velocity control to move the head at a velocity calculated based on a moving distance of the non-servo range.

Abstract: A method is disclosed for writing servo patterns for tracks on a rotating magnetic disk medium of a disk drive. Servo patterns are written on a reference track of the disk medium. Track following of the written servo patterns on the reference track is performed using a servo loop having a closed-loop response. A position error signal is generated for the reference track based on the track following. A correction signal is generated based on the track following using an observer of a one-dimensional state model that is equivalent to a two-dimensional state model of the servo loop. Servo patterns are written on a target track during track following of the reference track. The position error signal of the servo loop is adjusted based on the correction signal to reduce radial error propagation from the reference track to the target track.

Abstract: To solve the conventional problem in a disk drive unit that frequent interruptions be produced in a processor each time a head transits on a servo gate. To cope with the above-mentioned problem, a head drive unit 17 performs an off-track check using servo information read by the head 2 whenever the head 2 transits on each servo gate. Thus, an interruption processing required by the processor 16 is limited to the cases of either an operation completion interruption which is produced when a read/write operation is completed normally, or an error interruption which is produced on occurrence of the off-track or read error. This enables to reduce the number of interruption processing times performed in the processor 16, which results in reducing the load of the processor 16.

Abstract: A servo mark detector detects a servo mark from each servo information item detected by the servo detector. A counter measures a time period each time a servo mark is detected, thereby measuring a servo interval. A correction circuit corrects a time period T2 on the basis of the measured servo interval and an ideal servo interval. A determination circuit determines which one of the time period T2 and a time period T2? obtained by correcting the time period T2 should be used. A servo-sector-pulse-generating unit generates a servo sector pulse a time period T1 after the detection of each servo mark, and generates a pseudo servo sector pulse when the time period determined by the determination circuit has elapsed after the detection of each servo mark, if the next servo mark is not detected during the determined time period.

Abstract: The seek control means corresponds to a velocity control system which produces a target value based upon a target track, a present position, and a remaining distance from a commencement of a seek operation up to a time instant when a sign of an operating amount is changed; and the seek control means corresponds to a Two Degree of Freedom control system which sets an waveform by a function of time as a target value after the time instant when the sign of the operating amount is changed. The hard disk drives applies a velocity control system based upon a deviation of head positions as to a VCM voltage saturation and a uniform velocity mode, and also, applies a Two Degree of Freedom control system with employment of a function of time having a smooth locus in a decelerated velocity mode so as to suppress residual vibrations.

Abstract: Techniques for detecting control data, such as servo data, from input or incoming data read from a magnetic recording medium in the presence of radial incoherence are provided. More specifically, the techniques employ multiple (i.e., two or more) data detectors for choosing between multiple sampling phases associated with the input data read from the magnetic recording medium. In the context of servo data detection, such techniques offer several orders of magnitude in performance improvement in detecting SAM and Gray data in the presence of RI and may advantageously be employed in a read channel integrated circuit. Furthermore, such techniques may be applied to any data encoding system.

Abstract: A disc drive with an information portion previously written on a rotatable disc surface, a servo write clock generator phase lock loop circuit controlling timing for writing a reference mark to the rotatable disc surface in substantial time alignment and phase and frequency coherent with the information portion previously written to the rotatable disc surface, a servo write clock generator phase lock loop circuit controlling timing for writing the reference mark, a pulse detector circuit for creating logic level signals from the reference mark, a pattern generator for generating reference mark write signals from the logic level signals, a memory buffer for storing radial position correction tables and values for writing the reference mark, and a self-servo control and sequencing circuit synchronizing timing signals for writing the reference mark to rotatable disc surface of disc drive.

Abstract: A method of interleaving servo information fields on a recording medium, and a corresponding recording medium having interleaved servo information fields, that reduce the amount of disk surface area needed for servo information, to thus increase disk surface area available for data storage. The track layout includes regular sector servo fields and reduced sector servo fields interleaved with data fields. The regular sector servo fields include servo correction information such as repetitive run-out (RRO) cancellation values. The servo correction information of the reduced sector servo field does not include servo correction information. The servo correction information of the reduced sector servo field is merged into the regular sector servo field.

Abstract: On the basis of the position of a first target track specified by a command from a host, a CPU calculates a first offset value reflecting a track pitch that enables the adverse effects of crosstalk to be suppressed. The first offset value indicates an offset of a target position at which a head is to be actually positioned from a predetermined position on the first target track. The CPU determines a second target track, to which the target position belongs, and a second offset value on the basis of the position of the first target track and the calculated first offset value. The second offset value indicates an offset of the target position from the predetermined position on the second target track. The CPU positions the head at the target position on the determined second target track on the basis of the determined second target track position and second offset value.

Abstract: A servo method and system for generating a position error signal in a disk drive including a magnetic data storage disk rotating relative to a base, a data transducer assembly positioned at concentric data tracks by a rotary actuator referenced to the base and controlled by a digital servo system, the data transducer assembly having a magnetoresistive (MR) read element, the digital servo system employing multiple servo bursts in servo sectors embedded within the data tracks. During servo track positioning/following for each target head position relative to a track, a plurality of the servo bursts are selected, and combinations of the burst amplitudes of the selected servo bursts are obtained. A substantially continuous position error signal (C_PES) is generated based on the combinations of the burst amplitudes, indicating radial position of the read head relative to the target position.

Abstract: To improve the track density by reducing the discontinuity of servo patterns to be generated by a servo track writer, some servo areas existing in one circuit of a magnetic disk are formed at the consecutive first and second circuits of a servo track writer by averaging a plurality of position signals detected from servo patterns at the first and second circuits of the magnetic disk.

Abstract: An improved system and method for implementing a rotary memory device, including a host system and a disk-shaped memory medium storing position information, or a servo address mark (SAM). If a head fails to read a valid SAM, a dummy SAM is generated to prevent an arm with a read/write head from entering a neutral state. If the normal state cannot be restored within a fixed number of intervals, the system goes into the emergency brake control mode. In this emergency brake control mode, the direction of the head is determined, and the VCM current is applied in such a way drive the arm in the opposite direction. Damage to the magnetic medium and subsequent data loss problems are reduced because the velocity of the head is reduced to a safe level.

Abstract: A head position control system for a dual stage actuation disk drive system. A feedback system is provided for modifying a primary and a secondary input command signal to produce primary and secondary error signals. A controller receives the primary error signal and transmits primary actuator arm positioning information to the primary actuator. A secondary controller receives the secondary error signal and transmits secondary actuator arm positioning information to the secondary actuator. The feedback system creates a position error signal (PES) using information from servo wedges and runout information and the PES is used to produce the secondary error signal. The feedback system produces a reconstructed error signal including angular position information for the primary actuator arm by processing a back electromotive force signal from the primary actuator. The primary error signal is produced by modifying the primary input signal with the reconstructed error signal.

Abstract: A disk drive has a data recording medium such as a disk, a spindle motor for rotating the disk, disk rotation speed controlling logics for supplying a spindle current to the above described spindle motor to rotate the disk at a constant speed, a head unit for accessing the disk, an actuator for moving the head unit, and head position controlling logics for driving the actuator and controlling the position of the head unit. The head position controlling logic obtains the value of the spindle current and controls the position of the head unit on the basis of the above described spindle current value by using the fact that the spindle current varies according to variations in the position of the head unit.

Abstract: A multi-actuator disk storage device has at least two actuators respectively mounting plural product heads. Servo writing is performed using the product heads themselves. A first servo write operation is performed that includes operating a product head of the first actuator as a first clock head to generate first clock reference information for the product heads of the second actuator, which are operated as servo write heads to perform servo writing of disk areas associated with the second actuator using the first clock reference information. To servo write disk areas associated with the first actuator, a second servo write operation is performed. This operation includes operating a product head of the second actuator as a second clock head to generate second clock reference information for the product heads of the first actuator, which are operated as a servo write heads to perform servo writing using the second clock reference information.

Abstract: A method for writing timing marks on a rotatable storage medium, such as on a disk in a disk drive, includes the steps of: 1) during a rotation of the disk, detecting the passage of at least a portion of a first timing mark located at a first radius of the disk, and 2) writing a second timing mark at a second radius of the disk, the location of the second timing mark being based at least in part on a stored calculation of a delay from the time of passage of the first timing mark during a rotation of the rotatable storage medium. The location of the second timing mark is calculated based on alternative time intervals between detected timing marks and on various functions of the time intervals.

Abstract: The present invention is a method and apparatus for providing positional information of a disk. The disk has at least one side with a plurality of tracks, each having a first burst in a first servo field and a second burst in a second servo field. The first burst provides a first portion of track position information while the second burst provides a second portion of track position information. When combined, the first and second portions provide a position of a corresponding track. Each track further includes a third and a fourth burst that provides a first portion and a second portion of disk side position information. When combined, the first and second portions of disk side position information provide the disk side position of the disk. Each track also includes a burst that provides the quadrant position of the disk.