Patent US4638495A successfully refreshed from Google Patents.
US4638495A
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Automatic adaptive equalizer
Assignee: NEC Corp
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Filing: 1984-04-19
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Granted: 1987-01-20
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Expires: 2004-04-19
Abstract
Abstract In order to remove at least one of amplitude and delay distortions which tend to occur during signal transmission, the invention features circuitry wherein a received IF digital signal is fed through an equalizer circuit to a demodulator and wherein the demodulator outputs a series of data and error signals to a control signal generator. The control signal generator produces in-phase and quadrature control signals which are appropriately added and subtracted and subsequently averaged in an adder and subtracter circuit before being applied to a series of equalizers in the equalizer circuit.
Inventors
- 👤 Shoichi Mizoguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 12:40
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/01
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
127 words
An automatic adaptive equalizer for use in a digital radio transmission system, comprising: a first means for equalizing at least one of amplitude and delay distortions of an incoming IF signal; a demodulator being supplied with the output of said first means, and generating a plurality of data signals and a plurality of error signals; a control signal generator receiving said plurality of data signals and said plurality of error signals, and generating a plurality of in-phase control signals and a plurality of quadrature control signals; and a second means coupled to the output of said control signal generator, said second means performing additions and subtractions of said in-phase and quadrature control signals, and for applying the results of said addition and subtractions to said first means.
Claim 2
Dependent Claim
127 words
An automatic adaptive equalizer for use in a digital radio transmission system, comprising: a first means for equalizing at least one of amplitude and delay distortions of an incoming IF signal; a demodulator being supplied with the output of said first means, and generating a plurality of data signals and a plurality of error signals; a control signal generator receiving said plurality of data signals and said plurality of error signals, and generating a plurality of in-phase control signals and a plurality of quadrature control signals; and a second means coupled to the output of said control signal generator, said second means performing additions and subtractions of said in-phase and quadrature control signals, and for applying the results of said addition and subtractions to said first means.
Claim 3
Dependent Claim
60 words
An automatic adaptive equalizer as claimed in claim 1, further comprising a transversal filter provided between said first means and said demodulator such that the input and output of said transversal filter are coupled to the output of said first means and the input of said demodulator, respectively, said transversal filter being responsive to outputs of said control signal generator.
Claim 4
Dependent Claim
35 words
An automatic adapative equalizer as claimed in claim 1, wherein said first means comprises a linear amplitude distortion equalizer, a parabolic amplitude distortion equalizer, a linear delay distortion equalizer, and a parabolic delay distortion equalizer.
Claim 5
Dependent Claim
35 words
An automatic adaptive equalizer as claimed in claim 2, wherein said first means comprises a linear amplitude distortion equalizer, a parabolic amplitude distortion equalizer, a linear delay distortion equalizer, and a parabolic delay distortion equalizer.
References Cited (Backward Citations)
US3868576A
Cited
US4003006A
Cited
US4251782A
Cited
US4330861A
Cited
US4333063A
Cited
US4453256A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-01-19 | 1990-07-21 | 1991-01-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-01-19 | 1994-07-21 | 1995-01-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-01-19 | 1998-07-21 | 1999-01-20 | $7700.00 | Window Closed / Lapsed |