Patent US2185126A successfully refreshed from Google Patents.
Patent US4700364A successfully refreshed from Google Patents.
US4700364A
Expired / Lapsed
US
⏱️ 0.0 years remaining
FSK with continuous phase and continuous slope at bit transitions
Assignee: NEC Corp
•
Filing: 1985-09-30
•
Granted: 1987-10-13
•
Expires: 2005-09-30
Abstract
Abstract A FSK code with reduced high frequency content is generated. First through fourth waveforms are provided to a selector which selects one of the four waveforms in accordance with a control signal which, in turn, is generated in accordance with a state indication signal identifying the presently selected one of the four waveforms. A D/A converter converts the selected digital waveform data to an analog waveform signal. First and second of the digital waveform data represent +sin θ and -sin θ, and third and fourth of the digital waveform data represent +f(θ) and -f(θ, respectively, where ##EQU1## wherein 0≦θ≦2π and a, b and c are nonzero coefficients.
Inventors
- 👤 Tomohiro Miyazaki
- 👤 Tetsu Koyama
- 👤 Shinichi Koike
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 10:31
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/18; H04L27/20; H04L27/2003; H04L27/2021; H04L27/2025; H03; H03M; H03M5/00; H03M5/02; H03M5/04; H03M5/06; H03M5/12
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
159 words
An apparatus for generating a frequench shift keying (FSK) code comprising: generator means responsive to input data for generating first through fourth digital waveform data for first through fourth states, said first and second digital waveform data including data for +sin θ and -sin θ, respectively, said third and fourth digital waveform data including data for +f(θ) and -f(θ), respectively, ##EQU9## wherein 0≦θ≦2π and a, b and c are nonzero coefficients; said generator means also generating first through fourth state indication signals identifying said first through fourth digital waveform signals; respectively, selector means responsive to a control signal for selecting one of said first through fourth digital waveform data; controller means responsive to the input data and any of said first through fourth state indication signals immediately before said state indication signal for providing said control signal for said selector means, means for converting any of said first through fourth digital waveform data selected to an analog waveform signal.
Claim 2
Independent Claim
159 words
An apparatus for generating a frequench shift keying (FSK) code comprising: generator means responsive to input data for generating first through fourth digital waveform data for first through fourth states, said first and second digital waveform data including data for +sin θ and -sin θ, respectively, said third and fourth digital waveform data including data for +f(θ) and -f(θ), respectively, ##EQU9## wherein 0≦θ≦2π and a, b and c are nonzero coefficients; said generator means also generating first through fourth state indication signals identifying said first through fourth digital waveform signals; respectively, selector means responsive to a control signal for selecting one of said first through fourth digital waveform data; controller means responsive to the input data and any of said first through fourth state indication signals immediately before said state indication signal for providing said control signal for said selector means, means for converting any of said first through fourth digital waveform data selected to an analog waveform signal.
Claim 3
Dependent Claim
27 words
An apparatus for generating a FSK code set forth in claim 1, said generator means including memory means for storing said first through fourth digital waveform data.
Claim 4
Dependent Claim
31 words
An apparatus for generating a FSK code set forth in claim 2, said memory means including first through fourth memory means for storing said first through fourth digital waveform data, respectively.
Claim 5
Dependent Claim
27 words
An apparatus for generating a FSK code set forth in claim 1, said generator means including memory means for storing said first and third digital waveform data.
References Cited (Backward Citations)
US3048784A
Cited
US3223925A
Cited
US3325595A
Cited
US3377625A
Cited
US3987374A
Cited
US4339724A
Cited
US4410955A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-10-12 | 1991-04-13 | 1991-10-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-10-12 | 1995-04-13 | 1995-10-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-10-12 | 1999-04-13 | 1999-10-13 | $7700.00 | Window Closed / Lapsed |