Browse Prior Art Database

Improved Servo Pulse Detector

IP.com Disclosure Number: IPCOM000116834D
Original Publication Date: 1995-Nov-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Gale, ES: AUTHOR [+4]

Abstract

A method for improving the transient response of the Automatic Gain Control when used to detect timing based Position Error Signal servo signals is disclosed. The signal polarity is reversed based on tape motion direction such that detection is not required for the first peak of the waveform after the gap. Rather this peak is used to settle the AGC/detection loop.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 66% of the total text.

Improved Servo Pulse Detector

      A method for improving the transient response of the Automatic
Gain Control when used to detect timing based Position Error Signal
servo signals is disclosed.  The signal polarity is reversed based on
tape motion direction such that detection is not required for the
first peak of the waveform after the gap.  Rather this peak is used
to settle the AGC/detection loop.

      Timing based servo signals are used to generate PES information
for head/actuator servo.  A block diagram of the detection circuits
for this format is depicted in Fig. 1.  The equalized waveform and
detected waveform timings are depicted in Fig. 2.  When read from the
media the servo signals produce a waveform consisting of a series of
peaks and gaps in the detected waveform.  The servo decoder logic
uses the Gaps and either all positive or all negative peak
information
from the waveform to generate PES, so detection of only a single
polarity peak is required.  The polarity of the received servo signal
is tape motion dependent, that is, in the forward direction
the first peak is positive, in the reverse direction the first peak
is negative after a gap.

      Normally the proper detection of a large signal immediately
after a gap results is compromising AGC performance to prevent
unnacceptable transient response.  The invention makes use of the
properties of the servo waveform to improve AGC performance as
follows.  The first peak after the gap is n...