Browse Prior Art Database

Flexible Phase Servo Demodulator Integration Control

IP.com Disclosure Number: IPCOM000111059D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 4 page(s) / 102K

Publishing Venue

IBM

Related People

Cadloni, GL: AUTHOR [+2]

Abstract

Disclosed is a method that includes a programmable register in an existing Phase Servo Demodulator design, providing flexible microprocessor control of the number of Integration pulses.

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Flexible Phase Servo Demodulator Integration Control

      Disclosed is a method that includes a programmable register in
an existing Phase Servo Demodulator design, providing flexible
microprocessor control of the number of Integration pulses.

      Current Phase Servo Demodulation control hardware incorporate a
fixed number of Integration pulses each control cycle.  The number of
Integration pulses utilized by the Demodulator is proportional to the
length of the Servo burst.  Due to the fixed number of Integration
pulses, it is impossible to change the Servo burst length.  In a
Sector Servo application, the amount of space utilized by the Servo
burst is a direct loss in Data area.  Thus, an inflexible number of
Integration pulses can result in a loss of file Data capacity.

      A microprocessor control register can be incorporated into the
current Phase Servo Demodulator Integration control logic such that
the number of Integration pulses per Demodulation cycle can be
flexible.  This flexibility can be experimentally utilized to
determine the optimum number of Integration pulses necessary to
maintain proper Servo control at the same time that maximum Data
space efficiency can be maintained.

      Fig. 1 compares two Sector Servo Phase Encoded patterns.  Both
patterns contain a Servo Identification (SID) field and are
sandwiched between Data bursts.  The obvious difference between the
Fixed Length Demodulation Pattern and the Flexible Length
Demodulation Pattern is the duration of the Demodulation field.  As
shown, the Flexible Length Demodulation Pattern constitutes
considerable Data filed savings as depicted by the Data Space Lost
measurement.

      If future Sector Servo file specification figures are applied
to the savings depicted by this diagram, at least two 512 byte
sectors could be saved on every single track.

      The value n depicted in Fig. 2 can be defined as the
Demodulator Integration Count.  This value n, can be stored in a
microprocessor controlled...