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    Repeatable runout compensation value generation
    1.
    发明授权
    Repeatable runout compensation value generation 有权

    公开(公告)号：US11456014B1

    公开(公告)日：2022-09-27

    申请号：US17494825

    申请日：2021-10-05

    申请人： Western Digital Technologies, Inc.

    发明人： Zaifeng Chen ,  Chuanwen Ji

    IPC分类号： G11B5/596 ,  G11B20/10

    摘要： Generating a hard disk drive (HDD) data track repeatable runout (RRO) compensation value for a target track involves querying at least one RRO table for a closest track to the target track external servo target (EST) and identifying an ESTx corresponding to the closest track, computing a first absolute value of the difference between the EST and the ESTx, and responsive to the first absolute value being less than an approximation threshold, setting the RRO compensation value for the target track to the RRO compensation value for the closest track. Else, querying the RRO table(s) for each adjacent track to the target track, computing the difference between the ESTs for the adjacent tracks, and responsive to the second absolute value being less than an interpolation threshold, determining an RRO compensation value for the target track based on RRO compensation values corresponding to the adjacent tracks.

    Data storage device with notch filter calibration based on multi-rate excitation and error rejection
    3.
    发明授权
    Data storage device with notch filter calibration based on multi-rate excitation and error rejection 有权

    公开(公告)号：US11817122B1

    公开(公告)日：2023-11-14

    申请号：US17895640

    申请日：2022-08-25

    申请人： WESTERN DIGITAL TECHNOLOGIES, INC.

    发明人： Shinsuke Nakagawa ,  Zaifeng Chen ,  Hidehiko Numasato

    IPC分类号： G11B20/10 ,  G11B21/03 ,  G11B25/04

    CPC分类号： G11B20/10388 ,  G11B21/03 ,  G11B25/04

    摘要： Various illustrative aspects are directed to a data storage device, comprising one or more disks; an actuator mechanism configured to position one or more heads proximate to one or more disk surfaces of the one or more disks; and one or more processing devices, comprising an actuator mechanism control system configured for controlling the actuator mechanism. The processing devices are configured to: apply coefficients for a multi-rate notch filter to a servo control loop; measure a multi-rate error rejection transfer function; determine whether a peak of the multi-rate error rejection transfer function is greater than a multi-rate error rejection transfer function threshold; and modify, responsively to determining that the peak of the multi-rate error rejection transfer function is not greater than the multi-rate error rejection transfer function threshold, the parameters of the multi-rate notch filter based at least in part on the peak of the multi-rate error rejection transfer function.

    Per head, per profile finalize to move repeatable runout compensation values to NAND memory
    5.
    发明授权
    Per head, per profile finalize to move repeatable runout compensation values to NAND memory 有权

    公开(公告)号：US11482253B1

    公开(公告)日：2022-10-25

    申请号：US17506660

    申请日：2021-10-20

    申请人： Western Digital Technologies, Inc.

    发明人： Zaifeng Chen ,  Chuanwen Ji

    IPC分类号： G11B20/20 ,  G11B20/10 ,  G11B5/012

    摘要： Processing hard disk drive (HDD) data track repeatable runout (RRO) compensation data includes, for each read-write head constituent to the HDD, and for each data track on which the read-write head operates, saving RRO compensation data to single-level cell (SLC) area of a NAND memory component, and finalizing the RRO data before processing the next read-write head of the HDD, thereby minimizing the SLC area used. Finalizing the RRO data may include sorting the RRO data for the read-write head in the SLC area, moving the sorted RRO data from the SLC area to triple-level cell (TLC) or other higher-level cell area of the NAND, and then erasing the RRO data from the SLC area to free up that memory space, thereby reducing the risk of wearing out the TLC area.