Browse Prior Art Database

Servo Area Coding

IP.com Disclosure Number: IPCOM000085411D
Original Publication Date: 1976-Apr-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Baca, JP: AUTHOR [+3]

Abstract

Servo bursts or envelopes 1, 2 and 3, respectively, shown in the figure are derived from the servo tracks of a rotating head device of the type described in U. S. Patent 3,845,500 issued to Gary A. Hart and assigned to International Business Machines Corporation. The information derived from these servo patterns is used for head track alignment. Each servo burst has a double-frequency bit 10 at its midpoint, a ramp area 12 and a flat area 14.

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Servo Area Coding

Servo bursts or envelopes 1, 2 and 3, respectively, shown in the figure are derived from the servo tracks of a rotating head device of the type described in
U. S. Patent 3,845,500 issued to Gary A. Hart and assigned to International Business Machines Corporation. The information derived from these servo patterns is used for head track alignment. Each servo burst has a double- frequency bit 10 at its midpoint, a ramp area 12 and a flat area 14.

In order to determine when the rotating head is stepped from one track to another, a sequencing code is introduced within the flat area 14 of servo burst. To identify the code, a leading sync mark 16 and a trailing sync mark 18 are positioned symmetrical with double-frequency bit 10.

In operation, as the rotating head engages first sync mark 16 on tape, a counter begins to count. The counter will stop counting when the rotating head engages trailing sync mark 18. The contents of the counter will indicate whether or not the rotating head did step.

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