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Browse Prior Art Database

Technique of Nonlinear Write Effect Identification

IP.com Disclosure Number: IPCOM000100589D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Kurachi, K: AUTHOR [+3]

Abstract

A read-back signal of a hard disk drive contains peak shifts from both a writing process and a reading process on a high linear density recording. These bit-shifts are caused by a nonlinear write effect and an intersymbol interference, respectively.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 79% of the total text.

Technique of Nonlinear Write Effect Identification

       A read-back signal of a hard disk drive contains peak
shifts from both a writing process and a reading process on a high
linear density recording. These bit-shifts are caused by a nonlinear
write effect and an intersymbol interference, respectively.

      Disclosed is a simplified method for measuring the amount of
bit-shifts in the write and read processes separately.

      Provided that there is equipment which can write and read a
data pattern on a specific linear density using a head/disk
combination, and a data channel is a peak detection channel which has
a pulse- shaping circuit composed of a low-pass filter (to eliminate
the high frequency noise) and an equalizer (to slim the read back
pulse), the procedure is as follows.
(1) Write an arbitrary, encoded random pattern on a disk without the
write-precompensation.
(2) Read the pattern and perform a time-interval analysis of a
digital read data outputted from a peak detector on the following two
conditions.
(a) No equalization condition - this corresponds to no pulse
slimming, i.e., the digital read-data in this condition contains
bit-shifts from both the write and read processes.
(b) Full equalization condition - this corresponds to enough pulse
slimming for eliminating the intersymbol interference in the read
process, i.e., the digital read-data in this condition contains the
bit-shift from the write process only.

      The figure shows the...