US3864734A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pulse-code modulation detector and equalizer
Assignee: Bell and Howell Co
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Filing: 1973-01-05
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Granted: 1975-02-04
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Expires: 1993-01-05
Abstract
Abstract An apparatus for recovering pulse-code modulated digital data from a readback signal has equipment for partially equalizing the readback signal, and equipment for completing the partial equalization of the readback signal and for detecting the digital data. The latter equipment includes a delay device for delaying the partially equalized readback signal, equipment for providing a relatively undelayed version of the readback signal, and a differential amplifier for providing a digital signal corresponding to the difference between the delayed readback signal and the relatively undelayed version of the readback signal. The delay device includes a filter for completing the above mentioned partial equalization with the aid of the equipment for providing the relatively undelayed version of the readback signal and the mentioned differential amplifier.
Inventors
- 👤 David B Gish
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 10:24
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/02; G11B5/027; G11B5/035; H; H04; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03878
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
151 words
In apparatus for recovering pulse-code modulated digital data from a readback signal, the improvement comprising in combination: means for partially equalizing said readback signal comprising low-frequency equalizing means, mid-frequency equalizing means, and partial high-frequency equalizing means including only RC filter means as passive filter means; and means connected to said partial equalizing means for completing said partial equalization of said readback signal and for detecting said data, including means for delaying said partially equalized readback signal, means for providing a relatively undelayed version of said readback signal, and means for providing a digital signal corresponding to the difference between said delayed readback signal and said relatively undelayed version of said readback signal, said delay means including further filter means including only RC filters as passive filter means for completing said partial equalization with the aid of said means for providing said undelayed version and said means for providing said difference signal.
Claim 2
Dependent Claim
151 words
In apparatus for recovering pulse-code modulated digital data from a readback signal, the improvement comprising in combination: means for partially equalizing said readback signal comprising low-frequency equalizing means, mid-frequency equalizing means, and partial high-frequency equalizing means including only RC filter means as passive filter means; and means connected to said partial equalizing means for completing said partial equalization of said readback signal and for detecting said data, including means for delaying said partially equalized readback signal, means for providing a relatively undelayed version of said readback signal, and means for providing a digital signal corresponding to the difference between said delayed readback signal and said relatively undelayed version of said readback signal, said delay means including further filter means including only RC filters as passive filter means for completing said partial equalization with the aid of said means for providing said undelayed version and said means for providing said difference signal.
Claim 3
Dependent Claim
97 words
An apparatus as claimed in claim 1, wherein: said means for providing said undelayed version include means connected to said partial equalizing means for providing a relatively undelayed version of said partially equalized readback signal; and said means for providing said difference signal include means, connected to said further filter means included in said delay means and to said means for providing a relatively undelayed version of said partially equalized readback signal, for providing a digital signal corresponding to the difference between said delayed readback signal and said relatively undelayed version of said partially equalized readback signal.
Claim 4
Dependent Claim
29 words
An apparatus as claimed in claim 2, wherein: said delay means include means for delaying said partially equalized readback signal by one-half the cell period of said digital data.
Claim 5
Dependent Claim
29 words
An apparatus as claimed in claim 1, wherein: said delay means include means for delaying said partially equalized readback signal by one-half the cell period of said digital data.
Claim 6
Dependent Claim
28 words
An apparatus as claimed in claim 1, wherein: said means for providing said digital signal include limiter means for increasing the dynamic range of said equalization completing means.
Claim 7
Dependent Claim
20 words
An apparatus as claimed in claim 1, wherein: said further filter means of said delay means include Bessel filter means.
Claim 8
Dependent Claim
23 words
Apparatus as claimed in claim 1, wherein: said means for providing a relatively undelayed version of said readback signal comprise variable resistor means.
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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) | 1978-02-03 | 1978-08-05 | 1979-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-03 | 1982-08-05 | 1983-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-03 | 1986-08-05 | 1987-02-04 | $7700.00 | Window Closed / Lapsed |