Browse Prior Art Database

Identification Marker Encodement and Detection Method

IP.com Disclosure Number: IPCOM000115728D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 75K

Publishing Venue

IBM

Related People

Lui, CC: AUTHOR

Abstract

Disclosed is a method for encoding and detection of sector ID marker in sector servo application. This method not only is robust but also the stringent phase alignment requirement in servo write is relaxed.

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Identification Marker Encodement and Detection Method

      Disclosed is a method for encoding and detection of sector ID
marker in sector servo application.  This method not only is robust
but also the stringent phase alignment requirement in servo write is
relaxed.

      A marker is encoded with one burst of a single tone and
followed by another burst of a different tone.  Each tone frequency
is selected so the estimator output will always measure the true
amplitude of one tone and yield zero value for the other tone,
respectively.  In a preferred embodiment, one frequency is selected
at one-fourth of a system sampling clock frequency.  The other
frequency is at one-half of the sampling clock frequency which is
known as Nyquist frequency.  The first tone frequency is f sub 1 =
1/(4T) and the second tone f sub 2 = 1/(2T) where T is the sampling
clock period.

      Fig. 1 depicts an ID marker consisting of two bursts with
frequency f sub 1 and f sub 2, respectively.  There are four cycles
for the f sub 2 burst, and followed by two cycles of the f sub 1
burst, where a sub 1, a sub 2, a sub 3, a sub 4, ......., a sub 13, a
sub 14, a sub 15 and a sub 16 are samples at each consecutive clock
period.  Fig. 2 shows a detector implementation.  Marker burst signal
is first filtered and then sampled by an analog to digital converter
(ADC).  Digitized samples are steered into two accumulators, ACCU1,
ACCU2.  One accumulates all of the "odd" number samples, and the
other all "even" number samples.  The consecutive sample input to
ACCU1 and ACCU2 is to process by an alternate sign rule (+, -) and
then accumulation.  The cont...