Abstract: According to one embodiment, a position demodulation apparatus is provided which demodulates a first demodulated signal and a second demodulated signal, based on a servo-pattern read signal read out by a head from a medium, acquires a plurality of sets of a vector length and phase angle of vectors on a phase plane denoting the first and second demodulated signals, detects a phase angle for which the vector length is greatest based on the sets acquired, and executes rotational correction using the difference between the detected phase angle and a particular reference angle as a correction amount.

Abstract: According to one embodiment, a head position demodulating method and a magnetic disk device switch a demodulation window such that an amplitude of a fundamental wave component of a null-type burst pattern transitions from a decreasing direction to an increasing direction along with an increase in seek speed during demodulation of the null-type burst pattern recorded on a magnetic disk.

Abstract: According to one embodiment, a head position demodulating method and a magnetic disk device switch a demodulation window such that an amplitude of a fundamental wave component of a null-type burst pattern transitions from a decreasing direction to an increasing direction along with an increase in seek speed during demodulation of the null-type burst pattern recorded on a magnetic disk.

Abstract: According to one embodiment, a position demodulator includes a demodulator, a phase corrector, and a position demodulating module. The demodulator demodulates a first demodulated signal and a second demodulated signal having a phase difference of 90 degrees from the first demodulated signal as a result of discrete Fourier transform operation on a read signal of a null servo pattern recorded in a servo area of a medium read out by a head. The phase corrector carries out correction to tilt respective vectors of the first demodulated signal and the second demodulated signal represented on a phase plane by a predetermined angle. The position demodulating module demodulates a positional signal for determining the position of the core of the head based on the first demodulated signal and the second demodulated signal corrected by the phase corrector.

Abstract: According to one embodiment, a position demodulation method includes demodulating a first demodulation signal and a second demodulation signal having a phase difference of 90 degrees to the first demodulation signal based on a read-out signal obtained by reading out a servo pattern recorded on a medium by the head for positioning of a head with respect to the medium; correcting the first and second demodulation signals in which, when a trace of a Lissajous figure is drawn representing the first and second demodulation signals as values on coordinate axes different from each other on a plane, a ratio of respective lengths between intersections of the trace intersecting with two axes orthogonal at an origin of the plane is kept constant; and demodulating a positional signal for determining a position of the head based on the first and second demodulation signals after being corrected at the correcting.

Abstract: One aspect of the embodiment utilizes a servo frame interval correction apparatus which includes a detection unit for detecting a first servo frame formed on said recording medium. The apparatus includes an acquiring unit acquiring a detection time interval between said first servo frame and a second servo frame detected subsequently to the first servo frame from a table storing a detection time interval between a specific servo frame and a servo frame detected subsequently to the specific servo frame. The apparatus includes a differential calculation unit calculating a differential between the detection time interval acquired by said acquiring unit and a reference time interval; and a correction unit correcting an estimated position of said second servo frame based on the differential calculated by said differential calculation unit.

Abstract: According to one embodiment, a position demodulation method includes demodulating a first demodulation signal and a second demodulation signal having a phase difference of 90 degrees to the first demodulation signal based on a read-out signal obtained by reading out a servo pattern recorded on a medium by the head for positioning of a head with respect to the medium; correcting the first and second demodulation signals in which, when a trace of a Lissajous figure is drawn representing the first and second demodulation signals as values on coordinate axes different from each other on a plane, a ratio of respective lengths between intersections of the trace intersecting with two axes orthogonal at an origin of the plane is kept constant; and demodulating a positional signal for determining a position of the head based on the first and second demodulation signals after being corrected at the correcting.

Abstract: According to one embodiment, a position demodulator includes a demodulator, a phase corrector, and a position demodulating module. The demodulator demodulates a first demodulated signal and a second demodulated signal having a phase difference of 90 degrees from the first demodulated signal as a result of discrete Fourier transform operation on a read signal of a null servo pattern recorded in a servo area of a medium read out by a head. The phase corrector carries out correction to tilt respective vectors of the first demodulated signal and the second demodulated signal represented on a phase plane by a predetermined angle. The position demodulating module demodulates a positional signal for determining the position of the core of the head based on the first demodulated signal and the second demodulated signal corrected by the phase corrector.

Abstract: According to one embodiment, a disk storage apparatus includes a disk and a servo demodulator. The disk has a servo area, in which a first phase servo pattern, a second phase servo pattern that is in phase with the first servo pattern, and a third servo pattern that is inverse in phase to the first and second servo patterns. The third servo pattern comprises at least two phase servo pattern segments. The servo demodulator is configured to perform a phase servo demodulating process that includes integration operation on integration sections of the same ratio, using a read signal read from the servo area by a head.

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

Abstract: According to one embodiment, a storage medium that stores position information indicating positions of a plurality of tracks in a radial direction in the tracks, wherein the position information includes: a first pattern in which a feed angle indicating a phase difference between the tracks is an angle obtained by adding a predetermined angle to +90°; a second pattern in which the feed angle is an angle obtained by adding the predetermined angle to ?90°; and a third pattern in which the feed angle is the same as that of the first pattern.

Abstract: A storage device and a control device include a first DSP, a second DSP, and a Servo MPU for controlling a position of a head with respect to a storage medium. The Servo MPU instructs the first DSP and the second DSP. The first DSP carries out calculation of at least any of a demodulation calculation that is a calculation relating to demodulation of servo information and a digital filter calculation based on the instruction from the Servo MPU. The first DSP carries out a correction calculation that is a calculation relating to correction of the position based on the instruction from the Servo MPU. The Servo MPU carries out control of the position based on a result of the calculation carried out by the first DSP and the second DSP.

Abstract: According to one embodiment, a frequency control apparatus includes an eccentric component storage module, a frequency correction amount calculating module, and an oscillator control module. The eccentric component storage module stores in advance an eccentric component calculated by a discrete Fourier transform of the number of clock signals measured for each servo frame. The frequency correction amount calculating module calculates the number of clock signals corresponding to the servo frame based on the eccentric component stored in the eccentric component storage module and calculates a frequency correction amount corresponding to the servo frame based on the number of clock signals. The oscillator control module controls the operation of a frequency oscillator such that a frequency for oscillating a clock signal in the frequency oscillator is adjusted according to the frequency correction amount calculated by the frequency correction amount calculating module.

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

Abstract: One aspect of the embodiment utilizes a servo frame interval correction apparatus which includes a detection unit for detecting a first servo frame formed on said recording medium. The apparatus includes an acquiring unit acquiring a detection time interval between said first servo frame and a second servo frame detected subsequently to the first servo frame from a table storing a detection time interval between a specific servo frame and a servo frame detected subsequently to the specific servo frame. The apparatus includes a differential calculation unit calculating a differential between the detection time interval acquired by said acquiring unit and a reference time interval; and a correction unit correcting an estimated position of said second servo frame based on the differential calculated by said differential calculation unit.

Abstract: A servo-frame recording apparatus includes: a sector information rearranging section for rearranging serial bits of the sector information that is binary data; a first ExOR section for performing the ExOR (exclusive OR) on the sector information, the serial bits of which have been rearranged by said sector information rearranging section, and the track information, so that an exclusive logical sum is obtained; and a writing section for wiring the exclusive logical sum obtained by said ExOR section into the servo frame. With this configuration, a data length required for recording gray information and sector information can be shortened without lowering the reliability of a magnetic disk.

Abstract: An information storage apparatus that records servo information and user data on a recording face of a recording medium wherein a track density measuring unit measures the optimal track density for a recording face corresponding to each head targeting a storage medium on which the servo information has not yet been recorded and a recording density measuring unit measures the optimal linear density for each recording face. A servo frame writing unit writes the servo information varying a track pitch to a track pitch corresponding to the optimal track density measured by the track density measuring unit and a recording frequency to a recording frequency corresponding to the optimal linear density measured by the linear density measuring unit, for each head.

Abstract: A storage device and a control device include a DSP 21, a DSP 22, and a Servo MPU 12 for controlling a position of a head with respect to a storage medium. The Servo MPU 12 instructs the DSP 21 and the DSP 22. The DSP 21 carries out calculation of at least any of a demodulation calculation that is a calculation relating to demodulation of servo information and a digital filter calculation based on the instruction from the Servo MPU 12. The DSP 22 carries out a correction calculation that is a calculation relating to correction of the position based on the instruction from the Servo MPU. The Servo MPU 12 carries out control of the position based on a result of the calculation carried out by the DSP 21 and the DSP 22.

Abstract: A first and second phase patterns of which phases are the same and a third and fourth phase patterns of which phases are opposite of the first and second phase patterns and of which phases are different from each other, are formed on a recording medium. A position information in a first track range is demodulated based on a first phase difference of the regeneration signals of the first and second phase pattern and of the third phase pattern, position information in a second track range is demodulated based on a second phase difference of the regeneration signals in the third phase pattern and the fourth phase pattern, and position information in a third track range is demodulated based on the first phase difference according to an angle difference between the first phase difference and a phase of the regeneration signal in the third phase pattern.

Abstract: A recording apparatus capable of securely reading out data for causing a head to follow along circular tracks set virtually. Therefore, on-track control along the virtual tracks is possible by the conversion data on the discoid record medium even when, for example, the printed circuit board in a recording apparatus has been replaced.