Abstract: Various illustrative aspects are directed to a data storage device, method, and one or more processing devices that are configured to: during a read operation, open a servo gate in the selected head in order to read the first servo bursts, the sync mark, and the second servo bursts in one of the servo sectors; and determine a position error signal for the selected head based on reading the first servo bursts and the second servo bursts.

Abstract: Example storage medium servo patterns, data storage devices, and methods to provide servo tracks with multiple servo synchronization or servo address marks per servo sector in a data storage device are described. The data storage device may include storage media, such as magnetic disks, having servo sectors that define servo tracks, where each servo sector has a first servo address mark before the track identifier and a second servo address mark following the track identifier. Which servo address mark is used for processing the servo sector is based on the current servo operating mode, such as write operations versus seek operations.

Abstract: Example control circuitry, data storage devices, and methods to use dual servo channels for burst gain switching are described. The data storage device may include two servo channels, such as the dual channels in a two-dimensional magnetic recording channel, that receive read signals for the same servo sector in parallel. One channel is calibrated to use a gain value for a first portion of the servo pattern, such as the preamble and Gray code for the servo address mark, and the other channel is calibrated to use a different gain value for a second portion of the servo pattern, such as the burst pattern. The resulting signal values may then be combined to determine the position error signal. Both channels may be configured to use different gain values for different portions of the read signal with corresponding gain switching and combining them may use the most reliable portions of each signal.

Abstract: Example control circuitry, data storage devices, and methods to use dual servo channels for burst gain switching are described. The data storage device may include two servo channels, such as the dual channels in a two-dimensional magnetic recording channel, that receive read signals for the same servo sector in parallel. One channel is calibrated to use a gain value for a first portion of the servo pattern, such as the preamble and Gray code for the servo address mark, and the other channel is calibrated to use a different gain value for a second portion of the servo pattern, such as the burst pattern. The resulting signal values may then be combined to determine the position error signal. Both channels may be configured to use different gain values for different portions of the read signal with corresponding gain switching and combining them may use the most reliable portions of each signal.

Abstract: Example control circuitry, data storage devices, and methods for parallel self-servo writing of interleaved servo patterns in a data storage device are described. The data storage device may include multiple heads actuated over different surfaces of a data storage device and receive read signals from two different heads over two different surfaces in parallel. The servo wedges of the two surfaces may be offset to enable independent determination of phase while writing servo patterns in parallel to the two surfaces using their respective heads.

Abstract: Example control circuitry, data storage devices, and methods for determining wedge repeatable runout correction values for interleaved servo patterns in a data storage device are described. The data storage device may include multiple heads actuated over different surfaces of a data storage device and receive read signals from two different heads over two different surfaces in parallel. The servo wedges of the two surfaces may be offset to enable parallel learning of wedge repeatable runout correction values.

Abstract: Example storage medium servo patterns, data storage devices, and methods to provide servo tracks with continuously varying frequency in a data storage device are described. The data storage device may include storage media, such as magnetic disks, having servo sectors that define servo tracks, where adjacent servo tracks have continuously varying frequency as the head moves from one servo track to the next. As the head is actuated over the storage medium, a target track frequency may be determined based on the radial position of a target servo track and the channel frequency may be set to the target track frequency to follow the target servo track.

Abstract: Various illustrative aspects are directed to a data storage device, comprising one or more disks; an actuator mechanism configured to position heads proximate to a recording medium of the disks; a spindle motor configured for rotating the one or more disks; and one or more processing devices comprising a servo control processor. The servo control processor is configured to receive a spindle speed error signal indicative of an error in a rotational speed of the spindle motor. The servo control processor is further configured to output an initial frequency offset signal, wherein the initial frequency offset signal is proportional to the spindle speed error signal.

Abstract: A data storage device comprises a disk having a plurality of data tracks and a plurality of servo wedges wherein the plurality of servo wedges comprise a plurality of wedge repeatable runout (WRRO) fields configured to store a plurality of WRRO compensation values in connection with the plurality of data tracks. The data storage device may also include a read/write head configured to be actuated over the disk, and a controller configured to gather position error signal (PES) data needed for computation of the WRRO compensation values during a field operation of the data storage device. The data storage device may be further configured to adjust a position of the read/write head based on the WRRO compensation values.

Abstract: A data storage device comprises a disk having a plurality of data tracks and a plurality of servo wedges wherein the plurality of servo wedges comprise a plurality of wedge repeatable runout (WRRO) fields configured to store a plurality of WRRO compensation values in connection with the plurality of data tracks. The data storage device may also include a read/write head configured to be actuated over the disk, and a controller configured to gather position error signal (PES) data needed for computation of the WRRO compensation values during a field operation of the data storage device. The data storage device may be further configured to adjust a position of the read/write head based on the WRRO compensation values.

Abstract: A data storage device is disclosed comprising a first disk comprising first servo sectors A0-AN distributed around a circumference of the first disk, and a second disk comprising second servo sectors B0-BN distributed around a circumference of the second disk, wherein the second servo sectors B0-BN are offset circumferentially from the first servo sectors A0-AN. While the first and second disks are rotating second servo information is transmitted from a second servo channel to a first servo channel. One of the first servo sectors Ai is read to generate first servo information, and a first command value is generated based on the first servo information and the second servo information, wherein a first actuator is controlled based on the first command value.

Abstract: Write control bits are associated with servo pattern data bits to selectively disable or enable a write gate in a HDD write channel for self-servo writing after being sealed but before being vended to a user. The write gate can be disabled and enabled without deenergizing the write channel. A single write delay is calculated from one timing mark to the next to enable writing the next timing mark and portions of the radial pattern and servo pattern between the timing marks.

Abstract: Write control bits are associated with servo pattern data bits to selectively disable or enable a write gate in a HDD write channel for self-servo writing after being sealed but before being vended to a user. The write gate can be disabled and enabled without deenergizing the write channel. A single write delay is calculated from one timing mark to the next to enable writing the next timing mark and portions of the radial pattern and servo pattern between the timing marks.

Abstract: A method and apparatus for providing combined radial and timing multislot self-servowrite propagation is disclosed. Radial bursts are combined with each timing mark and requires only three recovery/read-write spacing allocations per sector. The channel operates without requiring the writing of any bursts between reading radial bursts.

Abstract: Write control bits are associated with servo pattern data bits to selectively disable or enable a write gate in a HDD write channel for self-servo writing after being sealed but before being vended to a user. The write gate can be disabled and enabled without deenergizing the write channel. A single write delay is calculated from one timing mark to the next to enable writing the next timing mark and portions of the radial pattern and servo pattern between the timing marks.

Abstract: Write control bits are associated with servo pattern data bits to selectively disable or enable a write gate in a HDD write channel for self-servo writing after being sealed but before being vended to a user. The write gate can be disabled and enabled without deenergizing the write channel. A single write delay is calculated from one timing mark to the next to enable writing the next timing mark and portions of the radial pattern and servo pattern between the timing marks.