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Variable Gain Amplifier Gain Presetting for Enhanced Recovery

IP.com Disclosure Number: IPCOM000104550D
Original Publication Date: 1993-May-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Kerwin, GJ: AUTHOR

Abstract

A method for presetting the gain of a data channel variable gain amplifier (VGA) to minimize the gain set-up time when switching between heads and recovering from a write operation. The method contains an algorithm for predetermining the optimal starting gain value and applying this value prior to a read operation.

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This is the abbreviated version, containing approximately 100% of the total text.

Variable Gain Amplifier Gain Presetting for Enhanced Recovery

      A method for presetting the gain of a data channel variable
gain amplifier (VGA) to minimize the gain set-up time when switching
between heads and recovering from a write operation.  The method
contains an algorithm for predetermining the optimal starting gain
value and applying this value prior to a read operation.

      The method described herein is a technique that allows a
variable gain amplifier (VGA) which is used in an automatic gain
control (AGC) to be preset to a near optimal value for a magnetic
recording head that is about to read.  This is accomplished by
performing a series of read operations at time of manufacturing that
determine the optimal AGC control voltage for each head at a series
of radii.  The value of the control voltage is noted and stored on a
protected data cylinder of the disk drive for later retrieval.  These
stored values would be read into a RAM when starting the drive.  The
VGA would then be preset to the control voltage which corresponds to
minimum recovery, sufficiently prior to a read operation to allow
amplitude recovery that is not only minimal but is independent of the
operation or data bits associated with the previously written record.
The figure describes the procedure for defining, storing, and
retrieving the preset AGC control voltages.