Dismiss
InnovationQ will be updated on Sunday, Jan. 21, from 9am - 11am ET. You may experience brief service interruptions during that time.
Browse Prior Art Database

# Servo-Burst Offset Cancellation Method for Hard Disk Drive

IP.com Disclosure Number: IPCOM000116539D
Original Publication Date: 1995-Sep-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 42K

IBM

## Related People

Fukushima, Y: AUTHOR [+2]

## Abstract

Disclosed is a method for servo-burst offset cancellation on Hard Disk Drive (HDD).

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Servo-Burst Offset Cancellation Method for Hard Disk Drive

Disclosed is a method for servo-burst offset cancellation on
Hard Disk Drive (HDD).

The servo-burst signals have some offset due to magnetic or
electrical noise, non-linearity of peak hold circuit, or electrical
offset.  Those offset causes non-linearity of positioning error
signal.  The method described below can cancel those burst offset by
the microprocessor on HDD.

The Figure shows the one example of the servo-burst information
on the disk.  Amplitude of Burst-A,B,C is detected by the
microprocessor using A/D convertor.  The microprocessor measures and
calculates the average value of the amplitude for Burst-C during
idling.

The microprocessor then calculates the positioning error signal
for servo control with offset cancellation.  The following flow shows
this method:
Idling
Gray = n + 1 ?
when yes
Calculate the average value of Burst-C and store in (c_min)
Calculation for Positioning Error
a = (Amplitude of Burst-A) - (c_min)
b = (Amplitude of Burst-B) - (c_min)
c = (Amplitude of Burst-C) - (c_min)
Main positioning error signal(mpes) = a/ (a + b)
Slave positioning error signal(spes) = c/ (a + b)

This method can also be applied for 4 burst-servo pattern.