Method and system for time-shift based rotational vibration sensing in disk drives

1. A method of sensing a rotational vibration of a hard disk drive including a rotating disk therein, comprising:

analyzing a time shift of reference bits spread on the rotating disk received in said hard disk drive;

utilizing a bandpass filter to process a signal representing said time shift;

wherein said bandpass filter comprises a highpass filter.

2. The method of claim 1 , wherein said method is implemented solely in digital electronics.

3. The method of claim 1 , wherein said method is implemented in software in combination with a very large scale integrated (VLSI) structure.

4. A method of sensing a rotational vibration of a hard disk drive including a rotating disk therein, comprising:

analyzing a time shift of reference bits spread on the rotating disk received in said hard disk drive;

wherein sensitivity of the method is minimized against linear vibration and treats an output signal as resulting from rotational vibration excitation of the disk drive.

5. A method of sensing a rotational vibration of a hard disk drive including a rotating disk therein, comprising:

analyzing a time shift of reference bits spread on the rotating disk received in said hard disk drive;

further comprising:

removing an average or repeatable time between reference bits.

6. A method of sensing a rotational vibration of a hard disk drive including a rotating disk therein, comprising:

analyzing a time shift of reference bits spread on the rotating disk received in said hard disk drive;

wherein said analyzing observes only at a change in time interval between reference bits regardless of an absolute length of time.

7. The method of claim 6 , wherein the time shift between reference bits is chosen to maximize resolution.

8. The method of claim 7 , wherein one reference bit is sampled every predetermined “k” sectors for a disk drive with a predetermined high sector count, such that there is sufficient time for said rotational vibration to establish a predetermined significant change.

9. The method of claim 6 , wherein multiple ones of the reference bits are provided per sector for a disk drive with a predetermined low sector count.

10. A method of sensing a rotational vibration of a hard disk drive including a rotating disk therein, comprising:

analyzing a time shift of reference bits spread on the rotating disk received in said hard disk drive;

further comprising:

measuring, based on said analyzing, a quality of a servo writer, with regard to uniformity of sectors and closure of a last written sector.

11. A system for sensing a rotational vibration of a disk drive, said disk drive including a rotating disk and said rotating disk including a plurality of reference bits across a surface thereof, comprising:

a detector for detecting said reference bits across a pattern on said disk;

an analyzer for analyzing a time interval between adjacent ones of said reference bits;

a bandpass filter for processing a signal representing said time shift; and,

wherein said bandpass filter comprises a highpass filter.

12. The system of claim 11 , wherein said system is implemented solely in digital electronics.

13. The system of claim 11 , wherein said system is implemented in software in combination with a very large scale integrated (VLSI) structure.

14. A method of sensing a rotational vibration of a disk drive, said disk drive including a rotating disk and said disk including a plurality of reference bits across a surface thereof, comprising:

detecting said reference bits across a pattern on said rotating disk;

analyzing a time interval between adjacent ones of said reference bits; and

inserting an additional reference bit between adjacent ones of said reference bits, to create a finer resolution.