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Browse Prior Art Database

Adaptive Boundary Adjustment Circuit for (1,7) Maximum Likelihood Channel

IP.com Disclosure Number: IPCOM000115583D
Original Publication Date: 1995-May-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Li, RY: AUTHOR [+2]

Abstract

A circuit was proposed to provide an adaptive adjustment on the (1,7) Maximum Likelihood (ML) boundary set to compensate for under or over equalization. The prior art uses fixed boundary set.

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Adaptive Boundary Adjustment Circuit for (1,7) Maximum Likelihood
Channel

      A circuit was proposed to provide an adaptive adjustment on the
(1,7) Maximum Likelihood (ML) boundary set to compensate for under or
over equalization.  The prior art uses fixed boundary set.

      (1,7) ML uses boundary sets to do decode magnetic readback data
into binary 1's and 0's.  In the prior art, the boundary sets are
predetermined and fixed for all heads and all files.  Because of the
manufacturing tolerances, certain misequalizations will occur which
can lead to sub-optimal file performances such as degraded soft error
rates.

      By detecting the misequalizations, the boundary sets can be
adaptively adjusted to compensate for component tolerances and aging
induced changes.  A circuit has been proposed to determine
misequalization and, in conjunction with a table look up, to provide
the necessary adjustments to the boundary sets.  The adjustments can
be made at time of manufacturing and, under microcode control,
periodically thereafter during the life of the file.