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US4320499A
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System for multi-level data transmission by means of an angle-modulated carrier having a constant amplitude
Assignee: US Philips Corp
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Filing: 1980-03-12
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Granted: 1982-03-16
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Expires: 2000-03-12
Abstract
Abstract A system for transmitting n-level data signals by means of an angle-modulated carrier having a constant amplitude and a continuous phase. The constant amplitude enables amplification in non-linear transmitter output stages. Associated with the n-levels are k(k>n) phase variations in accordance with such a rule, depending on preceding phase variations, that the spectrum of the angle-modulated signal becomes narrower. In a symbol interval the phase of the carrier changes by an amount from the sequence extending from -(k-1)π/n to (k+1)π/n in increments of 2π/n. The receiver is formed by a differential n-phase receiver. The system is used inter alia for radio transmission of digital information.
Inventors
- 👤 Dirk Muilwijk
- 👤 Cornelis B. Dekker
- 👤 Frank de Jager
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 18:04
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/18; H04L27/22; H04L27/227; H04L27/2275; H04L27/20; H04L27/2032; H04L27/2035
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
157 words
A system for transmitting n-level data signals from a transmitter to a receiver, the transmitter comprising a carrier oscillator and a modulator connected thereto for generating an angle-modulated carrier having a substantially constant amplitude and a continuous phase, characterized in that the modulator comprises means for converting n-level data signals into intermediate k-level signals wherein k is greater than n, at least one of the n-level data signals having associated therewith two symbols of the intermediate k-level signal, the k-levels of the intermediate multi-level signal corresponding with the phase variations of the carrier signal in one symbol interval of the sequence ranging from -(k-1)π/n and to +(k-1)π/n in increments of a 2π/n in a one-to-one relationship and means for causing said phase variations to occur gradually, and that the receiver is formed by a differential n-phase receiver which comprises means for detecting in each symbol interval one out of n different phase variations in multiples of 2π/n.
Claim 2
Independent Claim
157 words
A system for transmitting n-level data signals from a transmitter to a receiver, the transmitter comprising a carrier oscillator and a modulator connected thereto for generating an angle-modulated carrier having a substantially constant amplitude and a continuous phase, characterized in that the modulator comprises means for converting n-level data signals into intermediate k-level signals wherein k is greater than n, at least one of the n-level data signals having associated therewith two symbols of the intermediate k-level signal, the k-levels of the intermediate multi-level signal corresponding with the phase variations of the carrier signal in one symbol interval of the sequence ranging from -(k-1)π/n and to +(k-1)π/n in increments of a 2π/n in a one-to-one relationship and means for causing said phase variations to occur gradually, and that the receiver is formed by a differential n-phase receiver which comprises means for detecting in each symbol interval one out of n different phase variations in multiples of 2π/n.
Claim 3
Dependent Claim
45 words
A system as claimed in claim 1, characterized in that said modulator further comprises means for choosing between said two symbols of the k-level signal in dependence on the variation of the phase of the angle-modulated carrier in at least the two preceding symbol intervals.
Claim 4
Dependent Claim
76 words
A system as claimed in claim 1, characterized in that said means for converting the n-level data signal into the k-level intermediate signal comprises means for forming an n-level difference signal, by subtracting a second n-level signal modulo-n from the n-level data signal, and a k-level sum signal by adding the second n-level signal linearly to the n-level difference signal, the second n-level signal being derived by means of time delay from the n-level difference signal.
Claim 5
Dependent Claim
35 words
A system as claimed in claim 2, characterized in that the symbols of the k-level signal having associated therewith the same symbol of the n-level data signal have corresponding phase variations which differ by 2π.
References Cited (Backward Citations)
US3818135A
Cited
US4109101A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-03-15 | 1985-09-14 | 1986-03-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-03-15 | 1989-09-14 | 1990-03-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-03-15 | 1993-09-14 | 1994-03-16 | $7700.00 | Window Closed / Lapsed |