Browse Prior Art Database

Constant Position Gain Control

IP.com Disclosure Number: IPCOM000075738D
Original Publication Date: 1971-Nov-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Stephens, HC: AUTHOR

Abstract

This system provides a means for obtaining a constant gain to an electromechanical positioning system. Disk files inherently provide a read signal variation of the read-back signal's magnitude vs. the head position. Read-back signals typically vary by a ratio of 2/1 as the reading head moves from the outside to the inside cylinder. This variation becomes intolerable when the magnitude of the signal is used for any purpose and AGC systems have long been employed to correct for this variation in signal. This system is applicable to any disk or strip file that uses the signal from two adjacent cylinders to position a servo or read/write head.

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Constant Position Gain Control

This system provides a means for obtaining a constant gain to an electromechanical positioning system. Disk files inherently provide a read signal variation of the read-back signal's magnitude vs. the head position. Read-back signals typically vary by a ratio of 2/1 as the reading head moves from the outside to the inside cylinder. This variation becomes intolerable when the magnitude of the signal is used for any purpose and AGC systems have long been employed to correct for this variation in signal. This system is applicable to any disk or strip file that uses the signal from two adjacent cylinders to position a servo or read/write head.

Positioning of the servo head 1 is accomplished by separating the read signal into its two parts by separation circuits 4 and 5. Servo head 1 generates a composite signal that is a function of its position with respect to the two adjacent cylinders to which it is being referenced. Separation circuits 4 and 5 generate signals a' and b', respectively, where a' is a function of the servo head position with respect to one of the adjacent cylinders, and b' is a function of the servo head position with respect to the other adjacent cylinder. A positioning signal is obtained by subtracting a' and b' in subtractor 6.

It should be realized that the summation of the output signals a' and b' from separators 4 and 5 would be a constant value, if the amplitude of the read signal was constant as the servo head...