Appeal No. 1999-0216
Application No. 08/526,197
of servo tracks of a predetermined high gain servo pattern are
written. According to page 5, lines 21-32 of Appellants’
specification, the use of the high gain servo pattern, as
compared to a conventional phase modulated servo pattern,
produces a modified waveform with a minimized baseline and
reduced error due to head instability.
Claim 1 is illustrative of the invention and reads as
follows:
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 360 phase difference information within eacho
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
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