US4837642A
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Threshold tracking system
Assignee: Ampex Corp
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Filing: 1988-01-12
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Granted: 1989-06-06
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Expires: 2008-01-12
Abstract
Abstract A decoder system for decoding signals such as Class IV partial-response signals. In the decoder system, threshold levels are used to distinguish between binary ones and zeros in partial-response signals. The threshold levels are adjusted by a feedback system to automatically compensate for effects such as signal dropouts.
Inventors
- 👤 Peter Smidth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 06:21
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/06; H04L25/061; H04L25/065; G; G11; G11B; G11B20/00; G11B20/10; G11B20/10009; G11B20/14; G11B20/1403; G11B20/1407; G11B20/1419; H04L25/063; H04L25/38; H04L25/40; H04L25/49; H04L25/497
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
169 words
A method for decoding partial-response signals wherein decision threshold levels are automatically adjusted in proportion to variations in the amplitude of the partial-response signal, whose level at a specified clock time represents one binary state if the level exceeds a positive threshold level and represents another digital binary state if the level is below the threshold level, comprising the steps of: comparing the amplitude of a partial-response signal with the amplitude of a feedback signal; comparing the amplitude of the partial-response signal with a predetermined fraction of the amplitude of the feedback signal and providing an enable signal only when this comparison indicates that the partial-response signal exceeds the predetermined fraction of the feedback signal; only when an enable signal is present, increasing the charge on a charge storage device when the amplitude of the partial-response signal exceeds the amplitude of the feedback signal and decreasing the charge on the charge storage device when the amplitude of the partial-response signal is less than the amplitude of the feedback signal.
Claim 2
Independent Claim
169 words
A method for decoding partial-response signals wherein decision threshold levels are automatically adjusted in proportion to variations in the amplitude of the partial-response signal, whose level at a specified clock time represents one binary state if the level exceeds a positive threshold level and represents another digital binary state if the level is below the threshold level, comprising the steps of: comparing the amplitude of a partial-response signal with the amplitude of a feedback signal; comparing the amplitude of the partial-response signal with a predetermined fraction of the amplitude of the feedback signal and providing an enable signal only when this comparison indicates that the partial-response signal exceeds the predetermined fraction of the feedback signal; only when an enable signal is present, increasing the charge on a charge storage device when the amplitude of the partial-response signal exceeds the amplitude of the feedback signal and decreasing the charge on the charge storage device when the amplitude of the partial-response signal is less than the amplitude of the feedback signal.
Claim 3
Dependent Claim
39 words
A method according to claim 1 wherein a binary signal is provided as a result of the comparison of the threshold voltage signal with the predetermined fraction of the feedback signal, which binary signals represent the decoded partial-response signal.
Claim 4
Dependent Claim
12 words
A method according to claim 1 wherein the predetermined fraction is one-half.
Claim 5
Independent Claim
197 words
An apparatus for decoding partial-response signals whose amplitude at specified clock times represent a first binary state if the amplitude level exceeds a positive threshold and represents a second binary state if the signal level is below the threshold level comprising: rectifying means for providing full-wave rectification of a partial-response signal; first comparator means connected to compare the amplitude of full-wave rectified signals with the amplitude of a first feedback voltage signal; second comparator means connected for comparing the amplitude of the rectified signals with a second feedback signal which is a predetermined fraction of the first feedback signal; enabling means for providing an enable signal only when the comparison provided by the second comparator means indicates that the amplitude of the rectified partial-response signal exceeds the amplitude of the second feedback signal; a charge storage means; and charge pump means operative only in the presence of an enable signal for increasing the charge on the charge storage means when the amplitude of a rectified partial-response signal exceeds the first feedback signal and for decreasing the charge on the charge storage device when the amplitude of a rectified partial-response signal is less than the first feedback signal.
Claim 6
Independent Claim
197 words
An apparatus for decoding partial-response signals whose amplitude at specified clock times represent a first binary state if the amplitude level exceeds a positive threshold and represents a second binary state if the signal level is below the threshold level comprising: rectifying means for providing full-wave rectification of a partial-response signal; first comparator means connected to compare the amplitude of full-wave rectified signals with the amplitude of a first feedback voltage signal; second comparator means connected for comparing the amplitude of the rectified signals with a second feedback signal which is a predetermined fraction of the first feedback signal; enabling means for providing an enable signal only when the comparison provided by the second comparator means indicates that the amplitude of the rectified partial-response signal exceeds the amplitude of the second feedback signal; a charge storage means; and charge pump means operative only in the presence of an enable signal for increasing the charge on the charge storage means when the amplitude of a rectified partial-response signal exceeds the first feedback signal and for decreasing the charge on the charge storage device when the amplitude of a rectified partial-response signal is less than the first feedback signal.
Claim 7
Dependent Claim
20 words
A system according to claim 4 wherein the first and second comparator means include comparators which provide binary output signals.
Claim 8
Dependent Claim
41 words
A system according to claim 4 further including a first binary data transfer means connected to receive the output of the first comparator means and a second binary data transfer means connected to receive the output of the second comparator means.
Claim 9
Dependent Claim
48 words
A system according to claim 6 further including a clock means for generating periodic clock pulses whose periods determine sampling times for the partial-response signal, said clock means being connected to the first and second data transfer devices to control data transfer from their inputs to their outputs.
Claim 10
Dependent Claim
14 words
A system according to claim 4 wherein the charge storage device is a capacitor.
Claim 11
Dependent Claim
39 words
A system according to claim 4 wherein the charge pump means comprises a current source for selectively increasing the charge on the charge storage device and a current drain for selectively decreasing the charge on the charge storage device.
Claim 12
Dependent Claim
22 words
A system according to claim 4 wherein the enabling means comprises an AND-gate that is connected to the second data transfer means.
Claim 13
Dependent Claim
23 words
A system according to claim 10 wherein the AND-gate is also connected to receive the output signal from the first data transfer device.
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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) | 1992-06-05 | 1992-12-05 | 1993-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-06-05 | 1996-12-05 | 1997-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-06-05 | 2000-12-05 | 2001-06-06 | $7700.00 | Window Closed / Lapsed |