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Gain Compensation for PES Signal of Precoded Servo Pattern

IP.com Disclosure Number: IPCOM000089805D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Lim, JC: AUTHOR [+3]

Abstract

Servo patterns are employed in a disk file to provide position error signals to the servo circuits of the head-positioning system. They are generally prerecorded in the factory.

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Gain Compensation for PES Signal of Precoded Servo Pattern

Servo patterns are employed in a disk file to provide position error signals to the servo circuits of the head-positioning system. They are generally prerecorded in the factory.

Servo tracks written with a conventional dibit pattern produce variable Position Error Signal Gain (PES) depending on the radial position of the track. The gain decreases from the inside track to the outside track, as a result of the higher side read, caused by the increased physical spacing of transitions at the outside track.

The ratio of inner track gain to outer track gain can approach unity if the timing of the dibit pulse is variable, shorter dibit write-pulses being written on the outer tracks and progressively longer dibit write-pulses being written on the inner tracks. The variable timing of the dibit pulses compensates for the difference in gain so that the ratio of inner track gain to outer track gain is approximately unity.

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