Apparatus and method to calibrate servo sensors in a noisy environment

a technology of servo sensors and noise, applied in the field of apparatus and methods to calibrate servo sensors in a noisy environment, can solve the problems of guiding process substantial noise, data error on the immediately adjacent data track, and negative guiding signal to noise ratio

Inactive Publication Date: 2005-03-08
INT BUSINESS MASCH CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

As the result, the data tracks may vary from the desired positions, i.e. be “squeezed” together, such that writing on one track with a write element that is subject to track misregistration (TMR) may cause a data error on the immediately adjacent data track.
Another approach, however, is required for open channel guiding in which the magnetic tape can move laterally a distance which is substantially greater than the separation between index positions, thereby introducing substantial noise into the guiding process.
The guiding signal to noise ratio thus becomes negative, with the guiding noise being far larger than the step from one ratio to another, making it difficult to gather data points with a monotonic slope to conduct a calibration of the servo ratios.

Method used

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Embodiment Construction

This invention is described in preferred embodiments in the following description with reference to the Figures, in which like numbers represent the same or similar elements. The invention will be described as embodied in an apparatus and method to calibrate servo sensors. The following description of Applicant's apparatus and method is not meant, however, to limit Applicant's invention to magnetic tapes or to data processing applications, as the invention herein can be applied generally to calibrating transducers in an electrically noisy environment.

FIG. 1 shows magnetic tape data storage system 100. Control unit 110 receives and transmits data and control signals to and from a host device 102 via an interface 105. The control unit 110 is coupled to a memory device 107, such as a random access memory for storing information and computer programs. An example of a host device 102 comprises an IBM RS / 6000 processor.

A multi-element tape head 190 includes a plurality of read / write eleme...

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Abstract

A method and apparatus to calibrate a servo sensor disposed on a tape head located adjacent a moving magnetic tape is disclosed where that magnetic tape includes at least one servo edge comprising an interface between a first recorded signal and a second recorded signal, and where the servo sensor provides a servo signal, and where an independent position sensor provides an IPS signal. The method first samples the servo signal and the IPS signal, calculates a transfer function, and forms a first calibration curve. The method then forms an average residual error value. If that average residual error exceeds the maximum allowable residual error, then the method applies an offset to the first calibration curve to form a second calibration curve. That second calibration curve is saved for subsequent use during, for example, read / write / erase operations.

Description

FIELD OF THE INVENTIONThis invention relates to an apparatus and method to calibrate one or more servo sensors in a “noisy” environment. In certain embodiments, this invention relates to servo track following a moving magnetic tape having one or more servo edges of dissimilar recorded servo signals, and, more particularly, to calibrating one or more indexed servo positions offset laterally from those one or more servo edges.BACKGROUND OF THE INVENTIONAutomated media storage libraries are known for providing cost effective access to large quantities of stored media. Tape cartridges containing a moveable magnetic tape are often used in automated data storage libraries. Tape media, such a magnetic tape, is a common medium for the storage of data to be utilized by a computer. Magnetic tape has found widespread use as a data storage medium because it provides a relatively inexpensive solution for storing large amounts of data.Magnetic tape data storage typically provides one or more prer...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G11B5/584
CPCG11B5/584
Inventor CHLIWNYJ, ALEXSWANSON, DAVID L.WILLS, STEVEN C.
Owner INT BUSINESS MASCH CORP
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