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US5712873A
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Multi-mode equalizer in a digital video signal processing system
Assignee: Technicolor USA Inc
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Filing: 1996-06-04
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Granted: 1998-01-27
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Expires: 2016-06-04
Abstract
Abstract A digital high definition television receiver equalizer system includes an input adaptive feed forward filter (FFF 20), a carrier recovery network (46), and a slicer (40) in addition to an adaptive decision feedback filter (DFF, 30) for removing intersymbol interference. At the beginning of a blind equalizing interval the FFF is not adapted and the DFF operates as a linear filter with adapted coefficients for equalizing post-ghosts. Afterwards in the blind interval the FFF coefficients are adapted blindly for equalizing pre-ghosts. In a subsequent decision-directed mode the slicer output is used for adapting both the FFF and DFF non-linearly.
Inventors
- 👤 Dong-Chang Shiue
- 👤 Kumar Ramaswamy
- 👤 Paul Gothard Knutson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 09:09
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/14; H04N5/21; H04N5/211
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
140 words
A system for processing a received signal containing a constellation of symbols and subject to exhibiting unwanted perturbations, comprising an adaptive feed forward filter (FFF) for equalizing said received signal; an adaptive decision feedback filter (DFF) for equalizing said received signal; and a demodulator responsive to an equalized signal, wherein said FFF exhibits (1) non-adaptive operation during an initial phase of a non-decision directed equalizing interval, (2) non-decision directed adaptive operation during a later phase of said non-decision directed equalizing interval, and (3) decision-directed adaptive operation during a final equalizing interval following said non-decision directed equalizing interval; and said DFF exhibits (1) non-decision directed adaptive linear operation during said initial non-decision directed equalizing phase, (2) non-decision directed adaptive linear operation during said later phase of non-decision directed equalizing interval, and (3) non-linear decision-directed adaptive operation during said final equalizing interval.
Claim 2
Independent Claim
140 words
A system for processing a received signal containing a constellation of symbols and subject to exhibiting unwanted perturbations, comprising an adaptive feed forward filter (FFF) for equalizing said received signal; an adaptive decision feedback filter (DFF) for equalizing said received signal; and a demodulator responsive to an equalized signal, wherein said FFF exhibits (1) non-adaptive operation during an initial phase of a non-decision directed equalizing interval, (2) non-decision directed adaptive operation during a later phase of said non-decision directed equalizing interval, and (3) decision-directed adaptive operation during a final equalizing interval following said non-decision directed equalizing interval; and said DFF exhibits (1) non-decision directed adaptive linear operation during said initial non-decision directed equalizing phase, (2) non-decision directed adaptive linear operation during said later phase of non-decision directed equalizing interval, and (3) non-linear decision-directed adaptive operation during said final equalizing interval.
Claim 3
Dependent Claim
114 words
A system according to claim 1 wherein said demodulator is responsive to an output signal from at least one of said FFF and DFF, said demodulator including a control network for providing a control signal representing a carrier frequency offset of a received signal, and a first rotator for rotating a received symbol constellation in a first direction in response to said control signal to achieve demodulation; a second rotator responsive an output signal of said demodulator for rotating said demodulator output signal in a direction opposite to that of said first rotator to produce a re-rotated symbol constellation signal; and means for applying said re-rotated signal to said DFF to be equalized thereby.
Claim 4
Dependent Claim
31 words
A system according to claim 2, wherein said demodulator includes a symbol slicer, said slicer having an input and an output, said output being decoupled during said non-decision directed equalizing interval.
Claim 5
Dependent Claim
16 words
A system according to claim 1, wherein said non-decision directed interval is a blind equalizing interval.
Claim 6
Dependent Claim
128 words
In a system for processing a received signal subject to exhibiting unwanted perturbations, said system including a feedforward filter (FFF) and a decision-feedback filter (DFF), a method for equalizing said signal comprising the steps of: (a) during an initial phase of a non-decision directed equalizing interval (1) operating said FFF in a static condition wherein coefficients of said FFF are not updated; (2) adapting said DFF in a non-decision directed manner; (b) during a subsequent phase of said non-decision directed equalizing interval (1) adapting said FFF in a non-decision directed manner; (2) adapting said DFF in a non-decision directed manner; and (c) during an equalizing interval following said non-decision directed equalizing interval (1) adapting said FFF in a decision-directed mode; (2) adapting said DFF in a decision-directed mode.
Claim 7
Dependent Claim
128 words
In a system for processing a received signal subject to exhibiting unwanted perturbations, said system including a feedforward filter (FFF) and a decision-feedback filter (DFF), a method for equalizing said signal comprising the steps of: (a) during an initial phase of a non-decision directed equalizing interval (1) operating said FFF in a static condition wherein coefficients of said FFF are not updated; (2) adapting said DFF in a non-decision directed manner; (b) during a subsequent phase of said non-decision directed equalizing interval (1) adapting said FFF in a non-decision directed manner; (2) adapting said DFF in a non-decision directed manner; and (c) during an equalizing interval following said non-decision directed equalizing interval (1) adapting said FFF in a decision-directed mode; (2) adapting said DFF in a decision-directed mode.
Claim 8
Dependent Claim
32 words
A method according to claim 5, wherein said DFF operates as a linear filter in said non-decision directed equalizing interval; and said DFF operates as a non-linear filter in said following interval.
Claim 9
Dependent Claim
40 words
A method according to claim 5 including the further steps of (d) generating a control signal representing a carrier frequency offset of said received signal; and (e) applying said control signal to said FFF and DFF in said decision-directed mode.
Claim 10
Dependent Claim
16 words
A method according to claim 5, wherein said non-decision directed interval is a blind equalizing interval.
References Cited (Backward Citations)
US4227152A
Cited
US4309770A
Cited
US5598433A
Cited
US5539773A
Cited
US5537437A
Cited
US5414732A
Cited
US5506871A
Cited
WO1995003133A1
Cited
US5530485A
Cited
US5539774A
Cited
US5517213A
Cited
US5602872A
Cited
US5572547A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-01-26 | 2001-07-28 | 2002-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-01-26 | 2005-07-28 | 2006-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-01-26 | 2009-07-28 | 2010-01-27 | $7700.00 | Window Closed / Lapsed |