US5206853A
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Apparatus and method for detecting intersymbol interference
Assignee: Panasonic Holdings Corp
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Filing: 1991-02-27
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Granted: 1993-04-27
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Expires: 2011-02-27
Abstract
Abstract An apparatus for detecting an intersymbol interference occurred in a digital signal during signal transmission includes a test pattern generator, which would produce the largest intersymbol interference on a recording medium and reading the test pattern therefrom. The apparatus further includes a measuring circuit for measuring short transition intervals representing one bit pattern and producing a reproduction signal, and a rectangular signal with, reference to a predetermined threshold. The apparatus includes a calculating circuit for calculating the total intersymbol interference by a bit length and measured transition intervals. Furthermore, the apparatus detects the total intersymbol interference by measuring long transition intervals representing four series of bit patterns and the short transition intervals.
Inventors
- 👤 Shinichi Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 22:12
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/10009; G11B20/10046; G11B20/10212; G11B20/18; G11B20/1816; G11B20/182
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
96 words
An apparatus for detecting an intersymbol interference in a digital signal read out from a recording medium comprising: a clock generator for generating clock pulses having a predetermined cycle length; a pattern writing means for writing a predetermined data pattern on said medium, said data pattern having a short transition interval positioned between two long transition intervals; a reading means for reading said data pattern on said medium; a measuring means for measuring said short transition interval; and a calculating means for calculating an edge shift between said short transition interval and said long transition interval.
Claim 2
Independent Claim
96 words
An apparatus for detecting an intersymbol interference in a digital signal read out from a recording medium comprising: a clock generator for generating clock pulses having a predetermined cycle length; a pattern writing means for writing a predetermined data pattern on said medium, said data pattern having a short transition interval positioned between two long transition intervals; a reading means for reading said data pattern on said medium; a measuring means for measuring said short transition interval; and a calculating means for calculating an edge shift between said short transition interval and said long transition interval.
Claim 3
Dependent Claim
25 words
An apparatus for detecting an intersymbol interference as claimed in claim 1, wherein said pattern writing means writes said data pattern repeatedly on said medium.
Claim 4
Dependent Claim
35 words
An apparatus for detecting an intersymbol interference as claimed in claim 1, wherein said measuring means measures said short transition interval for a plurality of times, to produce an average of measured short transition intervals.
Claim 5
Dependent Claim
36 words
An apparatus for detecting an intersymbol interference as claimed in claim 1, wherein said reading means comprises a waveshaping means for shaping a waveform of said data pattern read by said reading means using a threshold.
Claim 6
Dependent Claim
64 words
An apparatus for detecting an intersymbol interference as claimed in claim 1, wherein said data pattern includes a first type data pattern in which said short transition interval is formed by at least one bit of a first level signal and a second type data pattern in which said short transition interval is formed by at least one bit of a second level signal.
Claim 7
Dependent Claim
53 words
An apparatus for detecting an intersymbol interference as claimed in claim 5, wherein said measuring means measures each of said short transition intervals of said first and second type data patterns for a plurality of times to produce averages of measured short transition intervals of said first and second type data patterns, respectively.
Claim 8
Dependent Claim
36 words
An apparatus for detecting an intersymbol interference as claimed in claim 6, wherein said measuring means produces a mean value of said averages of measured short transition intervals of said first and second type data patterns.
Claim 9
Dependent Claim
53 words
An apparatus for detecting an intersymbol interference as claimed in claim 5, wherein said reading means comprises a waveshaping means for shaping a waveform of said first and second data patterns read by said reading means using a threshold to produce said short transition intervals of said first and second type data patterns.
Claim 10
Dependent Claim
31 words
An apparatus for detecting an intersymbol interference as claimed in claim 8, wherein said threshold is varied to equalize said short transition intervals of said first and second type data patterns.
Claim 11
Dependent Claim
31 words
An apparatus for detecting an intersymbol interference as claimed in claim 1, wherein said pattern writing means comprises a beam producing means for writing spot marks which represent said data pattern.
Claim 12
Dependent Claim
35 words
An apparatus for detecting an intersymbol interference as claimed in claim 10, wherein said pattern writing means further comprises a beam control means to control said beam producing means to produced beams of different power.
Claim 13
Dependent Claim
96 words
An apparatus for detecting an intersymbol interference as claimed in claim 1, wherein said data pattern includes a first type data pattern in which said short transition interval .is formed by at least one bit of a first level signal and is surrounded by a plurality of bits of a second level signal in adjacent tracks, and a second type data pattern in which said short transition interval is formed by at least one bit of a second level signal and is surrounded by a plurality of bits of said first level signal in adjacent tracks.
Claim 14
Independent Claim
123 words
An apparatus for detecting an intersymbol interference in a digital signal read out and transmitted from a recording medium comprising: a pattern writing means for writing a predetermined data pattern on said medium, said data pattern having a short transition interval positioned between two long transition intervals, said short transition interval corresponding to M bit long data, said long transition interval corresponding to N bit long data, wherein N and M are integers and N being greater than M; a reading means for reading said data pattern on said medium; a measuring means for measuring said short transition interval and said long transition interval; and a calculating means for calculating an edge shift between said long transition interval and said short transition interval.
Claim 15
Independent Claim
123 words
An apparatus for detecting an intersymbol interference in a digital signal read out and transmitted from a recording medium comprising: a pattern writing means for writing a predetermined data pattern on said medium, said data pattern having a short transition interval positioned between two long transition intervals, said short transition interval corresponding to M bit long data, said long transition interval corresponding to N bit long data, wherein N and M are integers and N being greater than M; a reading means for reading said data pattern on said medium; a measuring means for measuring said short transition interval and said long transition interval; and a calculating means for calculating an edge shift between said long transition interval and said short transition interval.
Claim 16
Dependent Claim
18 words
An apparatus for detecting an intersymbol interference as claimed in claim 13, wherein said integer M is one.
Claim 17
Independent Claim
80 words
A method for detecting an intersymbol interference in a digital signal read out and transmitted from a recording medium comprising the steps of: generating clock pulses having a predetermined cycle length; writing a predetermined data pattern on said medium, said data pattern having a short transition interval positioned between two long transition intervals; reading said data pattern on said medium; measuring said short transition interval; and calculating an edge shift between said short transition interval and said long transition interval.
Claim 18
Independent Claim
80 words
A method for detecting an intersymbol interference in a digital signal read out and transmitted from a recording medium comprising the steps of: generating clock pulses having a predetermined cycle length; writing a predetermined data pattern on said medium, said data pattern having a short transition interval positioned between two long transition intervals; reading said data pattern on said medium; measuring said short transition interval; and calculating an edge shift between said short transition interval and said long transition interval.
Claim 19
Dependent Claim
25 words
A method for detecting an intersymbol interference as claimed in claim 15, further comprising the step of writing said data pattern repeatedly on said medium.
Claim 20
Dependent Claim
36 words
A method for detecting an intersymbol interference as claimed in claim 15, further comprising the step of measuring said short transition interval for a plurality of times to produce an average of measured short transition intervals.
Claim 21
Dependent Claim
31 words
A method for detecting an intersymbol interference as claimed in claim 15, further comprising the step of waveshaping a waveform of said data pattern which has been read, using a threshold.
Claim 22
Dependent Claim
65 words
A method for detecting an intersymbol interference as claimed in claim 15, further comprising the step of writing a first type data pattern in which said short transition interval is formed by at least one bit of a first level signal and a second type data pattern in which said short transition interval is formed by at least one bit of a second level signal.
Claim 23
Dependent Claim
58 words
A method for detecting an intersymbol interference as claimed in claim 19, wherein said measuring step further comprises the step of measuring each of said short transition intervals of said first and second type data patterns for a plurality of times to produce averages of measured short transition intervals of said first and second type data patterns, respectively.
Claim 24
Dependent Claim
41 words
A method for detecting an intersymbol interference as claimed in claim 20, wherein said measuring step further comprises the step of producing a mean value of said averages of measured short transition intervals of said first and second type data patterns.
Claim 25
Dependent Claim
52 words
A method for detecting an intersymbol interference as claimed in claim 19, wherein said waveshaping step further comprises the step of waveshaping a waveform of said first and second data patterns which have been read, using a threshold to produce said short transition intervals of said first and second type data patterns.
Claim 26
Dependent Claim
38 words
A method for detecting an intersymbol interference as claimed in claim 22, wherein said waveshaping step further comprised the step of varying said threshold to equalize said short transition intervals of said first and second type data patterns.
Claim 27
Dependent Claim
25 words
A method for detecting an intersymbol interference as claimed in claim 15, further comprising the step of producing spot marks which represent said data pattern.
Claim 28
Dependent Claim
32 words
A method for detecting an intersymbol interference as claimed in claim 24, wherein said producing step further comprises the step of controlling a beam producing means to produce beams of different power.
Claim 29
Dependent Claim
97 words
A method for detecting an intersymbol interference as claimed in claim 15, further comprising the step of writing a first type data pattern in which said short transition interval is formed by at least one bit of a first level signal and is surrounded by a plurality of bits of a second level signal in adjacent tracks, and a second type data pattern in which said short transition interval is formed by at least one bit of a second level signal and is surrounded by a plurality of bits of said first level signal in adjacent tracks.
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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) | 1996-04-26 | 1996-10-26 | 1997-04-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-04-26 | 2000-10-26 | 2001-04-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-04-26 | 2004-10-26 | 2005-04-27 | $7700.00 | Window Closed / Lapsed |