US5493454A
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Write precompensation optimization in a PRML channel using a selected PRML signal level
Assignee: Maxtor Corp
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Filing: 1994-10-04
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Granted: 1996-02-20
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Expires: 2014-10-04
Abstract
Abstract Write precompensation optimization for a partial response maximum likelihood ("PRML") magnetic recording channel adapted to a mass production environment. Optimal write precompensation may be determined by writing a tribit data pattern known to produce worst case nonlinear transition shift ("NLTS") onto a magnetic recording medium; reading back the recorded data pattern; and calculating the mean-squared error ("MSE") for one or more of the equalized data sample levels associated with the PRML channel to be optimized. The writing and reading back process is repeated with varying amounts of precompensation applied to the written pattern. The optimal amount of write precompensation is determined either by minimizing the MSE for a selected sample level or by minimizing MSE between the middle and the upper or lower of the ternary PRML sample levels.
Inventors
- 👤 Pablo A. Ziperovich
- 👤 Xiaodong Che
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:32
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/02; G11B20/00; G11B20/10; G11B20/10009; G11B20/10046; G11B20/10194; G11B20/10055; G11B27/00; G11B27/36; G11B20/12; G11B20/1217; G11B20/1258
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
173 words
A method of optimizing write precompensation in a PRML magnetic recording channel comprising the steps of: (a) applying a value of write precompensation to a predetermined data pattern thereby creating a precompensated data pattern; (b) writing said precompensated data pattern onto a magnetic recording medium; (c) reading said precompensated data pattern from said magnetic recording medium and generating therefrom a read signal; (d) inputing said read signal into said PRML channel, said PRML channel having an output providing a plurality of PRML signal levels; (e) sampling said read signal to obtain a series of read signal samples; (f) selecting one of said plurality of PRML signal levels; (g) calculating a mean-squared error value of read signal samples from said selected one of said PRML signal levels; and (h) repeating said steps of applying, writing, reading, inputing, sampling and calculating for said selected PRML signal level using a new value of write precompensation for each repetition until a minimum mean-squared error value of read signal samples from said selected PRML signal level is obtained.
Claim 2
Independent Claim
173 words
A method of optimizing write precompensation in a PRML magnetic recording channel comprising the steps of: (a) applying a value of write precompensation to a predetermined data pattern thereby creating a precompensated data pattern; (b) writing said precompensated data pattern onto a magnetic recording medium; (c) reading said precompensated data pattern from said magnetic recording medium and generating therefrom a read signal; (d) inputing said read signal into said PRML channel, said PRML channel having an output providing a plurality of PRML signal levels; (e) sampling said read signal to obtain a series of read signal samples; (f) selecting one of said plurality of PRML signal levels; (g) calculating a mean-squared error value of read signal samples from said selected one of said PRML signal levels; and (h) repeating said steps of applying, writing, reading, inputing, sampling and calculating for said selected PRML signal level using a new value of write precompensation for each repetition until a minimum mean-squared error value of read signal samples from said selected PRML signal level is obtained.
Claim 3
Dependent Claim
25 words
The method of claim 1 wherein said PRML magnetic recording channel comprises a class IV partial response channel characterized by the polynomial 1-D 2 .
Claim 4
Dependent Claim
20 words
The method of claim 1 wherein said magnetic recording medium is a rigid disk in a disk drive storage device.
Claim 5
Dependent Claim
27 words
The method of claim 1 wherein said predetermined data pattern is written around a recording track of a magnetic recording disk in a disk drive storage system.
Claim 6
Dependent Claim
14 words
The method of claim 4 wherein said predetermined data pattern comprises a tribit pattern.
Claim 7
Dependent Claim
39 words
The method of claim 5 wherein said PRML magnetic recording channel comprises a class IV partial response channel having an,output providing top, middle and bottom signal levels and wherein said selected PRML signal level is said middle signal level.
Claim 8
Dependent Claim
15 words
The method of claim 1 wherein said predetermined data pattern comprises a repeating tribit pattern.
Claim 9
Dependent Claim
40 words
The method of claim 7 wherein said PRML magnetic recording channel comprises a class IV partial response channel having an output providing top, middle and bottom signal levels and wherein said selected PRML signal level is said middle signal level.
Claim 10
Dependent Claim
27 words
The method of claim 1 further comprising the step of storing a value corresponding to said value of write precompensation that yielded said minimum mean-squared error value.
Claim 11
Dependent Claim
33 words
The method of claim 9 further comprising the step of using said stored value to select an amount of write precompensation to apply to any data pattern written onto said magnetic recording medium.
Claim 12
Dependent Claim
66 words
The method of claim 1 wherein said step of calculating said mean-squared error value comprises the steps of: (a) generating a series of read signal error values by subtracting expected sample values from said read signal samples; (b) taking the absolute value of said series of error values; and (c) integrating the absolute value of said series of error values from said selected PRML signal level.
Claim 13
Dependent Claim
61 words
The method of claim 1 wherein said step of calculating said mean-squared error value comprises the steps of: (a) generating a series of read signal error values by subtracting expected sample values from said read signal samples; (b) squaring said series of error values; and (c) integrating the square of said series of error values from said selected PRML signal level.
Claim 14
Dependent Claim
83 words
The method of claim 1 wherein said method is performed in each of a plurality of different frequency recording zones in a zoned recording disk drive storage system and further comprising the steps of saving a minimum mean-squared error value for each zone, selecting a particular zone for a data writing operation, and retrieving and applying a saved mean-squared error value for each selected zone thereby optimizing write precompensation for said selected recording zone before writing data to tracks located within the zone.
Claim 15
Dependent Claim
72 words
The method of claim 13 further comprising the steps of storing a series of write precompensation selection values corresponding to the amount of write precompensation that generated minimum mean-squared error during optimization of each of said recording zones; and using one of said stored write precompensation selection values to select an optimal amount of write precompensation when any data pattern is to be written to a selected one of said recording zones.
Claim 16
Independent Claim
264 words
A method of optimizing write precompensation in a PRML magnetic recording channel comprising the steps of: (a) applying a value of write precompensation to a predetermined data pattern thereby creating a precompensated data pattern; (b) writing said precompensated data pattern onto a magnetic recording medium; (c) reading said precompensated data pattern from said magnetic recording medium and generating therefrom a read signal; (d) inputing said read signal into said PRML channel, said PRML channel having an output providing a plurality of PRML signal levels; (e) sampling said read signal to obtain a series of read signal samples; (f) selecting a first of said plurality of PRML signal levels; (g) calculating a mean-squared error value of said read signal samples from said first selected PRML signal level; (h) selecting a second of said plurality of PRML signal levels; (i) repeating said steps of reading, inputing, sampling, and calculating to obtain a mean-squared error value of said read signal samples from said second selected PRML signal level; and (j) repeating said steps of applying, writing, reading, inputing, sampling and calculating a mean-squared error value of said read signal samples from said first selected PRML signal level, and said steps of reading, inputing, sampling and calculating a mean-squared error value of read signal samples from said second selected PRML signal level using a new value of write precompensation for each repetition until a difference between said mean-squared error value of read signal samples from said first selected PRML signal level and said mean-squared error value of read signal samples from said second PRML signal level is minimized.
Claim 17
Independent Claim
264 words
A method of optimizing write precompensation in a PRML magnetic recording channel comprising the steps of: (a) applying a value of write precompensation to a predetermined data pattern thereby creating a precompensated data pattern; (b) writing said precompensated data pattern onto a magnetic recording medium; (c) reading said precompensated data pattern from said magnetic recording medium and generating therefrom a read signal; (d) inputing said read signal into said PRML channel, said PRML channel having an output providing a plurality of PRML signal levels; (e) sampling said read signal to obtain a series of read signal samples; (f) selecting a first of said plurality of PRML signal levels; (g) calculating a mean-squared error value of said read signal samples from said first selected PRML signal level; (h) selecting a second of said plurality of PRML signal levels; (i) repeating said steps of reading, inputing, sampling, and calculating to obtain a mean-squared error value of said read signal samples from said second selected PRML signal level; and (j) repeating said steps of applying, writing, reading, inputing, sampling and calculating a mean-squared error value of said read signal samples from said first selected PRML signal level, and said steps of reading, inputing, sampling and calculating a mean-squared error value of read signal samples from said second selected PRML signal level using a new value of write precompensation for each repetition until a difference between said mean-squared error value of read signal samples from said first selected PRML signal level and said mean-squared error value of read signal samples from said second PRML signal level is minimized.
Claim 18
Dependent Claim
54 words
The method of claim 15 wherein said predetermined data pattern comprises a repeating tribit pattern and said magnetic recording medium comprises a magnetic recording disk having a multiplicity of concentrically displaced recording tracks in a disk drive storage system, said repeating tribit pattern written on at least one of said multiplicity of recording tracks.
Claim 19
Dependent Claim
56 words
The method of claim 16 wherein said PRML magnetic recording channel comprises a class IV partial response channel having an output providing top, middle and bottom signal levels and wherein said first selected PRML signal level is said middle level and said second selected PRML signal level is either said top or said bottom signal level.
References Cited (Backward Citations)
US5241429A
Cited
US5341249A
Cited
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