Claims
- 1. Apparatus for demodulating a phase modulated servo signal in a disk file, said servo signal having a baseline, said apparatus comprising:at least one disk mounted for rotation about an axis and having at least one disk surface for storing data; means for writing at a predefined location of said disk surface a series of servo tracks of a predetermined high gain servo pattern, said high gain servo pattern producing a readback signal where the baseline is minimized; said predetermined high gain servo pattern including 3600 phase difference information within each servo track; said predetermined high gain servo pattern providing said readback signal having a predetermined high phase change for a predetermined radial displacement and said readback signal being at the baseline a predetermined small percent of time, whereby said readback signal does not flatten out at the baseline; means for detecting said servo tracks for identifying servo phase information; and means for demodulating a phase modulated servo signal.
- 2. Apparatus for demodulating a phase modulated servo signal as recited in claim 1 wherein said means for writing at said predefined location of said disk surface said series of servo tracks of said predetermined high gain servo pattern include means for writing said series of servo tracks on ¼ data cylinder spacing and in an outer guard band of said disk surface.
- 3. Apparatus for demodulating a phase modulated servo signal as recited in claim 1 wherein said means for writing and for detecting said reference track includes a magneto-resistive (MR) transducer head.
- 4. Apparatus for demodulating a phase modulated servo signal as recited in claim 1 wherein said means for detecting said servo tracks for identifying servo phase information includes transducer means for generating said readback signal from said disk surface; filter means coupled to said transducer means for generating a first harmonic readback signal; zero-crossing comparator means coupled to said filter means for identifying zero-crossings of said first harmonic readback signal.
- 5. Apparatus for demodulating a phase modulated servo signal as recited in claim 1 wherein said means for writing at said predefined location of said disk surface said series of servo tracks of said predetermined high gain servo pattern includes means for writing two signals of the same frequency having a predetermined phase difference between adjacent servo tracks.
- 6. Apparatus for demodulating a phase modulated servo signal as recited in claim 5 wherein said predetermined phase difference between adjacent servo tracks is 45°.
- 7. A phase modulated servo method used in a disk file including at least one disk mounted for rotation about an axis and having at least one disk surface for storing data, said method comprising the steps of:writing at a predefined location of said disk surface a series of servo tracks of a predetermined high gain servo pattern, said servo pattern producing a readback signal having a base line where the baseline is minimized; and said predetermined high gain servo pattern including 360° phase difference information within each servo track; said predetermined high gain servo pattern providing said readback signal having a predetermined high phase change for a predetermined radial displacement and said readback signal being at the baseline a predetermined small percent of time, whereby said readback signal does not flatten out at the baseline; detecting said servo tracks for identifying servo phase information; and demodulating a phase servo signal.
- 8. A phase modulated servo method as recited in claim 7 wherein said writing step includes the steps of:writing said series of servo tracks on ¼ data cylinder spacing and in an outer guard band of said disk surface.
- 9. A phase modulated servo method as recited in claim 7 wherein said disk file includes a dedicated servo surface containing a plurality of servo tracks of standard gain servo pattern and wherein said series of servo tracks is written in an outer guard band of said disk surface and further includes the step of: writing at an inner guard band of said disk surface a series of servo tracks of said standard gain servo pattern.
- 10. (Three times amended) A direct access storage device comprising:a housing; at least one disk mounted in said housing for rotation about an axis and having at least one disk surface for storing data; transducer means mounted for movement across said disk surface for reading and writing data and predefined types of servo identification patterns to said disk surface; means for writing at a predefined location of said disk surface a series of servo tracks of a predetermined high gain servo pattern, said servo pattern producing a readback signal having a baseline where the baseline is minimized; and said predetermined high gain servo pattern including 360° phase difference information within each servo track; said predetermined high gain servo pattern providing said readback signal having a predetermined high phase change for a predetermined radial displacement and said readback signal being at the baseline a predetermined small percent of time, whereby said readback signal does not flatten out at the baseline; means for detecting said servo tracks for identifying servo phase information; and means for demodulating a phase servo signal.
Parent Case Info
This application is a continuation of application Ser. No. 08/125,959 filed Sep. 23, 1993 now abandoned.
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Continuations (1)
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Number |
Date |
Country |
Parent |
08/125959 |
Sep 1993 |
US |
Child |
08/526197 |
|
US |