US5309299A
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US
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Method and system for position error signal generation using auto correlation
Assignee: International Business Machines Corp
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Filing: 1992-10-07
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Granted: 1994-05-03
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Expires: 2012-10-07
Abstract
Abstract The present invention provides a method and system for generating a position error signal from a signal produced by a read element detecting a track comprising two harmonically unrelated patterns positioned parallel to each other on a magnetic media. The apparatus of the present invention produces a delayed signal from the read signal produced by the read element. The read signal is multiplied with the delayed signal to form a product signal. The product signal is integrated to produce a position error signal, wherein changes in the position error signal that are proportional to changes in position of the read element over the two patterns positioned parallel to each other on the magnetic media.
Inventors
- 👤 James F. Crossland
- 👤 Don G. East
- 👤 John A. Koski
- 👤 James E. Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 12:45
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/58; G11B5/584; G11B21/00; G11B21/02; G11B21/10
Claims Analysis
Total Claims: 44
Claim 1
Independent Claim
158 words
An apparatus for generating a position error signal from a read signal generated by a read element passing over a track comprising two patterns positioned parallel to each other on a magnetic media, the system comprising: first and second repetitive harmonically unrelated patterns disposed parallel to each other on the track; digitizing means coupled to the read element for producing a trinary representation of the read signal; delay means coupled to the read element for producing a delayed signal from the read signal; multiplication means coupled to the delay means for multiplying the read signal with the delayed signal to form a product signal; and integration means coupled to the multiplication means for integrating the product signal to produce a position error signal, wherein changes in the position error signal are proportional to changes in position of the read element over the first and second repetitive harmonically unrelated patterns positioned parallel to each other on the magnetic media.
Claim 2
Independent Claim
158 words
An apparatus for generating a position error signal from a read signal generated by a read element passing over a track comprising two patterns positioned parallel to each other on a magnetic media, the system comprising: first and second repetitive harmonically unrelated patterns disposed parallel to each other on the track; digitizing means coupled to the read element for producing a trinary representation of the read signal; delay means coupled to the read element for producing a delayed signal from the read signal; multiplication means coupled to the delay means for multiplying the read signal with the delayed signal to form a product signal; and integration means coupled to the multiplication means for integrating the product signal to produce a position error signal, wherein changes in the position error signal are proportional to changes in position of the read element over the first and second repetitive harmonically unrelated patterns positioned parallel to each other on the magnetic media.
Claim 3
Dependent Claim
13 words
The apparatus of claim 1, wherein the integration means comprises a low-pass filter.
Claim 4
Dependent Claim
17 words
The apparatus of claim 2, wherein the integration means further includes means to normalize the product signal.
Claim 5
Dependent Claim
31 words
The apparatus of claim 1, wherein the first pattern has a first frequency and the second pattern has a second frequency, and wherein the delay for the delay means is selectable.
Claim 6
Dependent Claim
59 words
The apparatus of claim 4, wherein the selectable delay is selected as follows: ##EQU16## where m and n are selected positive integers, f 1 is the first frequency, f 2 is the second frequency, T 1 =1/f 1 , T 2 =1/f 2 , and T delay is the delay, wherein m and n are chosen as follows: ##EQU17##
Claim 7
Dependent Claim
31 words
The apparatus of claim 4, wherein the delay means includes a memory, wherein the read signal is stored in the memory for a period of time set by the selectable delay.
Claim 8
Dependent Claim
14 words
The apparatus of claim 6, wherein the memory is structured as a shift register.
Claim 9
Dependent Claim
16 words
The apparatus of claim 6, wherein the memory is structured as a random access storage device.
Claim 10
Dependent Claim
19 words
The apparatus of claim 1, wherein the magnetic media is a magnetic tape utilized in a tape storage system.
Claim 11
Independent Claim
208 words
An apparatus for generating a position error signal relative to a track from a read signal produced by a read element passing over a magnetic media in response to the read element detecting a track comprising two patterns positioned parallel to each other on a magnetic media, the system comprising: first and second repetitive harmonically unrelated patterns disposed parallel to each other on the track; delay means coupled to the read element for producing a first delayed signal and a second delayed signal from the read signal generated by the read element; multiplication means coupled to the delay means for multiplying the read signal with the first delayed signal to form a first product signal and for multiplying the read signal with the second delayed signal to form second product signal; subtraction means coupled to the multiplication means for subtracting the first product signal from the second product signal to produce a differential signal; and integration means coupled to the subtraction means for integrating the differential signal to produce a position error signal, wherein changes in the position error signal are proportional to changes in position of the read element over the first and second repetitive harmonically unrelated patterns positioned parallel to each other on the magnetic media.
Claim 12
Independent Claim
208 words
An apparatus for generating a position error signal relative to a track from a read signal produced by a read element passing over a magnetic media in response to the read element detecting a track comprising two patterns positioned parallel to each other on a magnetic media, the system comprising: first and second repetitive harmonically unrelated patterns disposed parallel to each other on the track; delay means coupled to the read element for producing a first delayed signal and a second delayed signal from the read signal generated by the read element; multiplication means coupled to the delay means for multiplying the read signal with the first delayed signal to form a first product signal and for multiplying the read signal with the second delayed signal to form second product signal; subtraction means coupled to the multiplication means for subtracting the first product signal from the second product signal to produce a differential signal; and integration means coupled to the subtraction means for integrating the differential signal to produce a position error signal, wherein changes in the position error signal are proportional to changes in position of the read element over the first and second repetitive harmonically unrelated patterns positioned parallel to each other on the magnetic media.
Claim 13
Dependent Claim
13 words
The apparatus of claim 10, wherein the integration means comprises a low-pass filter.
Claim 14
Dependent Claim
43 words
The apparatus of claim 10 further comprising an automatic gain control circuit having an input coupled to the read element, wherein output of the automatic gain control circuit is coupled to the delay means to provide the delay means a normalized read signal.
Claim 15
Dependent Claim
61 words
The apparatus of claim 12 further comprising a comparator coupled to an output of the automatic gain control signal to determine whether the signal generated by the read element is above a selected level, wherein a signal above the selected level results in a valid signal being generated to indicate that the signal is usable for generating a position error signal.
Claim 16
Dependent Claim
14 words
The apparatus of claim 10, wherein the subtraction means comprises a difference amplifier circuit.
Claim 17
Dependent Claim
70 words
The apparatus of claim 10, wherein the delay means comprises a memory, wherein the first delayed signal is created by storing the read signal in the memory for a first period of time before retrieving the read signal from the memory and the second delayed signal is created by storing the read signal in the memory for a second period of time before retrieving the read signal from the memory.
Claim 18
Dependent Claim
94 words
The apparatus of claim 15, wherein the delay means further comprises an address generation means coupled to the memory for creating a first and second number of addresses utilized in storing, delaying, and retrieving the digitized read signal from the memory, the first delayed signal being generated when the digitized read signal is retrieved from the first number of addresses in the memory after a first delay and the second delayed signal being generated when the read digitized signal is retrieved from the second number of addresses in the memory after a second delay.
Claim 19
Dependent Claim
20 words
The apparatus of claim 16, wherein the address generation means comprises a counter and an adder coupled to the memory.
Claim 20
Independent Claim
126 words
An apparatus for generating a position error signal from a read signal generated by a read element passing over a track, the apparatus comprising: a first pattern having a first frequency parallel to a second pattern having a second frequency on a magnetic media, wherein the first and second patterns are located on the track are repetitive and harmonically unrelated; delay means for producing a delayed signal from the read signal; multiplication means for multiplying the read signal with the delayed signal to form a product signal; and integration means for integrating the product signal to produce a position error signal, wherein changes in the position error signal are proportional to changes in position of the read element over the first pattern and the second pattern.
Claim 21
Independent Claim
126 words
An apparatus for generating a position error signal from a read signal generated by a read element passing over a track, the apparatus comprising: a first pattern having a first frequency parallel to a second pattern having a second frequency on a magnetic media, wherein the first and second patterns are located on the track are repetitive and harmonically unrelated; delay means for producing a delayed signal from the read signal; multiplication means for multiplying the read signal with the delayed signal to form a product signal; and integration means for integrating the product signal to produce a position error signal, wherein changes in the position error signal are proportional to changes in position of the read element over the first pattern and the second pattern.
Claim 22
Dependent Claim
10 words
The apparatus of claim 18, wherein the delay is selectable.
Claim 23
Dependent Claim
59 words
The apparatus of claim 19, wherein the selectable delay is selected as follows: ##EQU18## where m and n are selected positive integers, f 1 is the first frequency, f 2 is the second frequency, T 1 =1/f 1 , T 2 =1/f 2 , and T delay is the delay, wherein m and n are chosen as follows: ##EQU19##
Claim 24
Dependent Claim
36 words
The apparatus of claim 18, wherein the delay means comprises storing the read signal in a memory for a selected period of time equal to the delay before retrieving the signal to generate the delayed signal.
Claim 25
Dependent Claim
13 words
The apparatus of claim 18, wherein the integration means comprises a low-pass filter.
Claim 26
Dependent Claim
15 words
The apparatus of claim 22, wherein the low-pass filter is a second order low-pass filter.
Claim 27
Dependent Claim
41 words
The apparatus of claim 18 further comprising an automatic gain control circuit coupled to the read element, wherein output of the automatic gain control circuit is coupled to the delay means to provide the delay means with a normalized read signal.
Claim 28
Dependent Claim
67 words
The apparatus of claim 23 further comprising a comparator coupled to the output of the automatic gain control circuit to determine whether the normalized read signal generated by the automatic gain control circuit is above a selected level, wherein a normalized read signal above the selected level results in a valid signal being generated to indicate that the signal is usable for generating a position error signal.
Claim 29
Independent Claim
121 words
A method for generating a position error signal from a read signal generated by a read element passing over a track having two patterns disposed parallel to each other on a magnetic media, the method comprising: generating a delayed signal from the read signal produced by the read element passing over two repetitive harmonically unrelated patterns positioned parallel to each other on the track; multiplying the read signal with the delayed signal to form a product signal; and integrating the product signal to produce a position error signal, wherein changes in the position error signal is proportional to changes in position of the read element over the two repetitive harmonically unrelated patterns positioned parallel to each other on the magnetic media.
Claim 30
Independent Claim
121 words
A method for generating a position error signal from a read signal generated by a read element passing over a track having two patterns disposed parallel to each other on a magnetic media, the method comprising: generating a delayed signal from the read signal produced by the read element passing over two repetitive harmonically unrelated patterns positioned parallel to each other on the track; multiplying the read signal with the delayed signal to form a product signal; and integrating the product signal to produce a position error signal, wherein changes in the position error signal is proportional to changes in position of the read element over the two repetitive harmonically unrelated patterns positioned parallel to each other on the magnetic media.
Claim 31
Independent Claim
151 words
A method for generating a position error signal from a read signal generated by a read element passing over a track having two patterns disposed parallel to each other on a magnetic media, the method comprising: generating a first and second delayed signal from the read signal produced by the read element passing over the two repetitive harmonically unrelated patterns positioned parallel to each other on the track; multiplying the read signal with the first delayed signal to form a first product signal; multiplying the read signal with the second delayed signal to form a second product signal; subtracting the first product signal from the second product signal to produce a subtracted signal; and integrating the subtracted signal to produce a position error signal, wherein changes in the position error signal are proportional to changes in the position of the unrelated patterns positioned parallel to each other on the magnetic media.
Claim 32
Independent Claim
151 words
A method for generating a position error signal from a read signal generated by a read element passing over a track having two patterns disposed parallel to each other on a magnetic media, the method comprising: generating a first and second delayed signal from the read signal produced by the read element passing over the two repetitive harmonically unrelated patterns positioned parallel to each other on the track; multiplying the read signal with the first delayed signal to form a first product signal; multiplying the read signal with the second delayed signal to form a second product signal; subtracting the first product signal from the second product signal to produce a subtracted signal; and integrating the subtracted signal to produce a position error signal, wherein changes in the position error signal are proportional to changes in the position of the unrelated patterns positioned parallel to each other on the magnetic media.
Claim 33
Dependent Claim
116 words
A data storage system comprising: a read element for producing a read signal upon detection of a servo track, wherein the servo track includes two repetitive patterns positioned parallel to each other on the servo track, the two patterns being harmonically unrelated to each other; delay means responsive to the read signal for producing a delayed read signal; multiplication means for multiplying the delayed read signal with the read signal to form a product signal; and integration means for integrating the product signal to produce a position error signal proportional to changes in contribution to the read signal by first and second repetitive and harmonically unrelated patterns in the read signal, produced by the read element.
Claim 34
Dependent Claim
116 words
A data storage system comprising: a read element for producing a read signal upon detection of a servo track, wherein the servo track includes two repetitive patterns positioned parallel to each other on the servo track, the two patterns being harmonically unrelated to each other; delay means responsive to the read signal for producing a delayed read signal; multiplication means for multiplying the delayed read signal with the read signal to form a product signal; and integration means for integrating the product signal to produce a position error signal proportional to changes in contribution to the read signal by first and second repetitive and harmonically unrelated patterns in the read signal, produced by the read element.
Claim 35
Dependent Claim
30 words
The data storage system of claim 28, further comprising an actuator responsive to the position error signal for adjusting a relative position of the read element and the servo track.
Claim 36
Dependent Claim
20 words
The data storage system of claim 29, wherein said actuator means adjusts the read element relative to the servo track.
Claim 37
Dependent Claim
17 words
The data storage system of claim 30, wherein the servo track is located on a magnetic media.
Claim 38
Independent Claim
158 words
An apparatus for generating a position error signal from a read signal generated by a read element passing over a track comprising two patterns positioned parallel to each other on a magnetic media, the system comprising: first and second repetitive harmonically unrelated patterns disposed parallel to each other on the track; digitizing means coupled to the read element for producing a trinary representation of the read signal; delay means coupled to the digitizing means for producing a delayed signal from the read signal; multiplication means coupled to the delay means for multiplying the read signal with the delayed signal to form a product signal; and integration means coupled to the multiplication means for integrating the product signal to produce a position error signal, wherein changes in the position error signal are proportional to changes in position of the read element over the first and second repetitive harmonically unrelated patterns positioned parallel to each other on the magnetic media.
Claim 39
Independent Claim
158 words
An apparatus for generating a position error signal from a read signal generated by a read element passing over a track comprising two patterns positioned parallel to each other on a magnetic media, the system comprising: first and second repetitive harmonically unrelated patterns disposed parallel to each other on the track; digitizing means coupled to the read element for producing a trinary representation of the read signal; delay means coupled to the digitizing means for producing a delayed signal from the read signal; multiplication means coupled to the delay means for multiplying the read signal with the delayed signal to form a product signal; and integration means coupled to the multiplication means for integrating the product signal to produce a position error signal, wherein changes in the position error signal are proportional to changes in position of the read element over the first and second repetitive harmonically unrelated patterns positioned parallel to each other on the magnetic media.
Claim 40
Dependent Claim
33 words
The apparatus of claim 32, wherein the read signal includes a true component and a complement component and wherein the multiplication means includes digital switching of the true component and the complement component.
Claim 41
Dependent Claim
26 words
The apparatus of claim 33, wherein the multiplication means includes degating the read signal when the delayed signal is represented by digital encoding defined as zero.
Claim 42
Dependent Claim
16 words
The apparatus of claim 34, wherein multiplication is defined for the weightings +1, 0, and -1.
Claim 43
Dependent Claim
74 words
The apparatus of claim 1, wherein the first and second harmonically unrelated patterns position parallel to each other on a magnetic media are related to each other by: ##EQU20## where f 1 is the frequency of the first pattern, f 2 is the frequency of the second pattern, n is a positive integer, and m is a positive integer, wherein m and n are chosen as follows: ##EQU21## where R delay is a delay.
Claim 44
Dependent Claim
74 words
The apparatus of claim 18, wherein the first and second harmonically unrelated patterns position parallel to each other on a magnetic media are related to each other by: ##EQU22## where f 1 is the frequency of the first pattern, f 2 is the frequency of ht second pattern, n is a positive integer, and m is a positive integer, wherein m and n are chosen as follows: ##EQU23## where T delay is a delay.
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| 3.5 Years (Year 4) | 1997-05-02 | 1997-11-01 | 1998-05-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-05-02 | 2001-11-01 | 2002-05-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-05-02 | 2005-11-01 | 2006-05-03 | $7700.00 | Window Closed / Lapsed |