US5233482A
Expired / Lapsed
US
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Thermal asperity compensation for PRML data detection
Assignee: HGST Netherlands BV
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Filing: 1991-07-31
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Granted: 1993-08-03
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Expires: 2011-07-31
Abstract
Abstract Apparatus and method of thermal asperity compensation are provided for data detection in a partial-response maximum-likelihood (PRML) data channel. The PRML data channel includes an analog to digital converter (ADC) having a normal operating range and a filter, gain and timing control coupled to the ADC. When a thermal asperity is detected, a thermal asperity recovery mode is established responsive to the detected thermal asperity. The gain and timing control are held and the normal operating range of the ADC is adjusted responsive to the thermal asperity recovery mode. Also an AC coupling pole frequency is elevated responsive to the thermal asperity recovery mode.
Inventors
- 👤 Richard L. Galbraith
- 👤 Gregory J. Kerwin
- 👤 Joey M. Poss
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 00:50
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/10009; G11B19/00; G11B19/02; G11B19/04; G11B20/18; G11B20/24; G11B5/00; G11B5/48; G11B5/58; G11B5/60; G11B5/6005; G11B5/6011; G11B5/6076
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
85 words
A method of thermal asperity compensation for data detection in a data channel including an analog to digital converter (ADC) having a normal operating range, filter, gain and timing control coupled to the ADC, said method comprising the steps of: detecting a thermal asperity; establishing a thermal asperity recovery mode responsive to said detected thermal asperity; holding the gain and timing control responsive to said thermal asperity recovery mode; and adjusting a normal operating range of the ADC responsive to said thermal asperity recovery mode.
Claim 2
Independent Claim
85 words
A method of thermal asperity compensation for data detection in a data channel including an analog to digital converter (ADC) having a normal operating range, filter, gain and timing control coupled to the ADC, said method comprising the steps of: detecting a thermal asperity; establishing a thermal asperity recovery mode responsive to said detected thermal asperity; holding the gain and timing control responsive to said thermal asperity recovery mode; and adjusting a normal operating range of the ADC responsive to said thermal asperity recovery mode.
Claim 3
Dependent Claim
25 words
A method as recited in claim 1 further comprising the step of: incrementing an AC coupling pole frequency responsive to said thermal asperity recovery mode.
Claim 4
Dependent Claim
44 words
A method as recited in claim 1 wherein the step of detecting a thermal asperity includes the steps of: detecting an amplitude of the sample values from the ADC; and comparing said detected amplitude with a predefined threshold value to identify a thermal asperity.
Claim 5
Dependent Claim
48 words
A method as recited in claim 1 wherein the step of detecting a thermal asperity includes the steps of: detecting an amplitude of a plurality of sample values from the ADC; and comparing said plurality of detected amplitudes with a predefined threshold value to identify a thermal asperity.
Claim 6
Dependent Claim
41 words
A method as recited in claim 4 further including the steps of: detecting the polarity of the thermal asperity; and invalidating a detected thermal asperity responsive to a change in said detected polarity before said plurality of sample values are detected.
Claim 7
Dependent Claim
56 words
A method as recited in claim 1 wherein said step of establishing a thermal asperity recovery mode responsive to said detected thermal asperity includes the step of: reducing the analog signal input to the ADC by a selected factor; and wherein said step of adjusting a normal operating range of the ADC utilizes said selected factor.
Claim 8
Dependent Claim
16 words
A method as recited in claim 1 wherein multiple rereads are performed over the detected asperity.
Claim 9
Dependent Claim
92 words
Apparatus for thermal asperity compensation for data detection in a partial-response maximum-likelihood (PRML) data channel including an analog to digital converter (ADC) having a normal operating range, filter, gain and timing control coupled to the ADC, said apparatus comprising: means for detecting a thermal asperity; means for establishing a thermal asperity recovery mode responsive to said detected thermal asperity; means for holding the gain and timing control responsive to said thermal asperity recovery mode; and means for adjusting a normal operating range of the ADC responsive to said thermal asperity recovery mode.
Claim 10
Dependent Claim
92 words
Apparatus for thermal asperity compensation for data detection in a partial-response maximum-likelihood (PRML) data channel including an analog to digital converter (ADC) having a normal operating range, filter, gain and timing control coupled to the ADC, said apparatus comprising: means for detecting a thermal asperity; means for establishing a thermal asperity recovery mode responsive to said detected thermal asperity; means for holding the gain and timing control responsive to said thermal asperity recovery mode; and means for adjusting a normal operating range of the ADC responsive to said thermal asperity recovery mode.
Claim 11
Dependent Claim
23 words
Apparatus as recited in claim 8 further comprising: means for incrementing an AC coupling pole frequency responsive to said thermal asperity recovery mode.
Claim 12
Dependent Claim
35 words
Apparatus as recited in claim 8 wherein said means for detecting a thermal asperity include: means for sampling values from said ADC; and means for threshold comparing said sampled values to detect said thermal asperity.
Claim 13
Dependent Claim
50 words
Apparatus as recited in claim 8 wherein said means for holding the gain and timing control responsive to said thermal asperity recovery mode; and said means for adjusting a normal operating range of the ADC responsive to said thermal asperity recovery mode are provided by a channel interface control unit.
Claim 14
Dependent Claim
55 words
Apparatus as recited in claim 8 wherein said means for adjusting a normal operating range of the ADC responsive to said thermal asperity recovery mode includes means for adjusting an analog signal coupled to said ADC by a selected factor; and wherein said normal operating range of the ADC is adjusted by said selected factor.
Claim 15
Dependent Claim
12 words
Apparatus as recited in claim 12 wherein said selected factor equals two.
Claim 16
Dependent Claim
164 words
A direct access storage device of the type including a partial-response maximum-likelihood (PRML) data channel comprising: a housing; at least one disk mounted in said housing for rotation about an axis and having at least one disk surface for storing data; transducer means mounted for movement across said disk surface for reading and writing data to said disk surface; an analog to digital converter (ADC) coupled to said transducer means for converting an analog input signal to digital sample values within a normal operating range; filter, gain and timing control means coupled to said ADC for controlling the ADC; means coupled to said ADC for threshold comparing said digital sample values to detect a thermal asperity; means for establishing a thermal asperity recovery mode responsive to said detected thermal asperity; means for holding the gain and timing control means responsive to said thermal asperity recovery mode; and means for adjusting said normal operating range of said ADC responsive to said thermal asperity recovery mode.
Claim 17
Dependent Claim
164 words
A direct access storage device of the type including a partial-response maximum-likelihood (PRML) data channel comprising: a housing; at least one disk mounted in said housing for rotation about an axis and having at least one disk surface for storing data; transducer means mounted for movement across said disk surface for reading and writing data to said disk surface; an analog to digital converter (ADC) coupled to said transducer means for converting an analog input signal to digital sample values within a normal operating range; filter, gain and timing control means coupled to said ADC for controlling the ADC; means coupled to said ADC for threshold comparing said digital sample values to detect a thermal asperity; means for establishing a thermal asperity recovery mode responsive to said detected thermal asperity; means for holding the gain and timing control means responsive to said thermal asperity recovery mode; and means for adjusting said normal operating range of said ADC responsive to said thermal asperity recovery mode.
Claim 18
Dependent Claim
27 words
A direct access storage device as recited in claim 14 further comprising: means for incrementing an AC coupling pole frequency responsive to said thermal asperity recovery mode.
Claim 19
Dependent Claim
41 words
A direct access storage device as recited in claim 14 further comprising means for reducing said analog input signal to said ADC by a selected factor and wherein said normal operating range of said ADC is adjusted by said selected factor.
Claim 20
Dependent Claim
29 words
A direct access storage device as recited in claim 14 further comprising: means responsive to said thermal asperity recovery mode for performing multiple reread operations over said detected asperity.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-08-02 | 1997-02-01 | 1997-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-08-02 | 2001-02-01 | 2001-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-08-02 | 2005-02-01 | 2005-08-03 | $7700.00 | Window Closed / Lapsed |