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US4803438A
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8-phase phase-shift keying demodulator
Assignee: NEC Corp
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Filing: 1987-07-08
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Granted: 1989-02-07
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Expires: 2007-07-08
Abstract
Abstract In order to rapidly bring a 8-phase phase shift keying demodulator into resynchronization upon the demodulator going out of synchronism, a plurality of error signals produced within the demodulator is used to determine whether a signal point of an incoming 8-phase phase modulated signal is usable for controlling a transversal filter. An asynchronism signal, which indicates whether the demodulator is synchronized, is derived from the demodulator and being applied to a tap gain control signal generator coupled to the transversal filter. The tap gain control signal generator is controlled when the asynchronism signal indicates asynchronism of the demodulator.
Inventors
- 👤 Shoichi Mizoguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:01
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/01; H04L27/18; H04L27/22; H04L27/227; H04L27/2271; H04L27/2273; H04L27/0014; H04L2027/0024; H04L2027/0026; H04L2027/0038; H04L2027/0042; H04L2027/0044; H04L2027/0071; H04L2027/0073; H04L2027/0079
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
158 words
An 8-phase phase-shift keying demodulator comprising: a transversal equalizer for equalizing an incoming 8-phase phase modulated signal, said transversal equalizer including a transversal filter and a tap gain control signal generator coupled to said transversal filter; first means coupled to said transversal filter and coherently demodulating the equalized signal; second means for generating a plurality of error signals third means for receiving said plurality of error signals and determining whether a signal point of said 8-phase phase modulated signal is usable for controlling said transversal equalizer, said third means producing a first output; fourth means for detecting asynchronism of said demodulator, said fourth means applying a second output to said tap gain control signal generator; and fifth means interposed between said third means and said tap gain control signal generator, receiving said first output and controlling a plurality of selectors forming part of said tap gain control signal generator when said second output indicates asynchronism of the demodulator.
Claim 2
Dependent Claim
158 words
An 8-phase phase-shift keying demodulator comprising: a transversal equalizer for equalizing an incoming 8-phase phase modulated signal, said transversal equalizer including a transversal filter and a tap gain control signal generator coupled to said transversal filter; first means coupled to said transversal filter and coherently demodulating the equalized signal; second means for generating a plurality of error signals third means for receiving said plurality of error signals and determining whether a signal point of said 8-phase phase modulated signal is usable for controlling said transversal equalizer, said third means producing a first output; fourth means for detecting asynchronism of said demodulator, said fourth means applying a second output to said tap gain control signal generator; and fifth means interposed between said third means and said tap gain control signal generator, receiving said first output and controlling a plurality of selectors forming part of said tap gain control signal generator when said second output indicates asynchronism of the demodulator.
Claim 3
Dependent Claim
81 words
An 8-phase phase-shift keying demodulator as claimed in claim 1, further comprising, sixth means for receiving said plurality of error signal and determining whether a level of said incoming 8-phase phase modulated signal is within a predetermined region according to said plurality of error signals, said six means producing a fourth output; and seventh means coupled to said sixth means, receiving said fourth output and controlling the level of said incoming 8-phase phase modulated signal in response to said fourth output.
Claim 4
Dependent Claim
42 words
An 8-phase phase-shift keying demodulator as claimed in claim 1, wherein said second means comprises a plurality of full-wave rectifiers and a plurality of binary decision circuits, said plurality of full-wave rectifiers being AC coupled to said plurality of binary decision circuits.
Claim 5
Dependent Claim
42 words
An 8-phase phase-shift keying demodulator as claimed in claim 2, wherein said second means comprises a plurality of full-wave rectifiers and a plurality of binary decision circuits, said plurality of full-wave rectifiers being AC coupled to said plurality of binary decision circuits.
Claim 6
Dependent Claim
42 words
An 8-phase phase-shift keying demodulator as claimed in claim 2, wherein said second means comprises a plurality of full-wave rectifiers and a plurality of binary decision circuits, said plurality of full-wave rectifiers being DC coupled to said plurality of binary decision circuits.
Claim 7
Dependent Claim
20 words
An 8-phase phase-shift keying demodulator as claimed in claim 1, wherein said first means includes a pair of phase detectors.
Claim 8
Dependent Claim
45 words
An 8-phase phase-shift keying demodulator as claimed in claim 2, wherein said seventh means includes a variable gain amplifier for amplifying the incoming 8-phase phase modulated signal, and a variable gain amplifier controller for controlling said variable gain amplifier in response to said fourth output.
Claim 9
Dependent Claim
39 words
An 8-phase phase-shift keying demodulator as claimed in claim 7, wherein said variable gain amplifier controller comprises a J-K flip-flop, and an averaging circuit connected to said J-K flip-flop for supplying a control signal to said variable gain amplifier.
Claim 10
Dependent Claim
160 words
An 8-phase phase-shift keying demodulator as claimed in claim 1, wherein said tap gain control filter generator further includes a correlator for supplying a plurality of control signals to said transversal filter, and a plurality of memory elements, each of said memory elements receiving a different one of said control signals from said correlator, each of said selectors having its output connected to a respective input of said transversal filter, and each of said selectors having a first input for receiving a different one of said control signals from said correlator and a second input for receiving an output of a different one of said memory elements, each of said selectors being operable for supplying a respective control signal from said correlator to said transversal filter when said second signal indicates synchronism of said demodulator, and being operable for supplying a respective output from said memory elements to said transversal filter when said second signal indicates asynchronism of said demodulator.
Claim 11
Dependent Claim
18 words
An 8-phase phase-shift keying demodulator as claimed in claim 9, wherein said memory element is a D-type flip-flop.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-02-07 | 1992-08-08 | 1993-02-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-07 | 1996-08-08 | 1997-02-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-07 | 2000-08-08 | 2001-02-07 | $7700.00 | Window Closed / Lapsed |