US4274067A
Expired / Lapsed
US
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Universal clock recovery network for QPSK modems
Assignee: Comsat Corp
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Filing: 1979-09-27
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Granted: 1981-06-16
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Expires: 1999-09-27
Abstract
Abstract A clock recovery network uses a voltage proportional to the incoming symbol rate as a coarse tuning signal to control the tuned center frequency of a voltage controlled oscillator. The incoming data is used to positively synchronize the oscillator to the incoming data stream.
Inventors
- 👤 Vasil Uzunoglu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 02:47
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/24; H04; H04L; H04L7/00; H04L7/02; H04L7/027; H04L7/0079; H04L7/0083
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
125 words
A clock recovery network for receiving an input data stream having a symbol clock rate and providing as an output a clock signal synchronized with said input data stream, said network comprising: oscillator means for receiving said input data stream and providing at its output a clock signal synchronized with said input data stream, said oscillator means being synchronized to said input data stream by means of synchronizing pulses generated from said input data stream, the free-running frequency of said oscillator means in the absence of said synchronizing pulses being determined by a coarse control voltage; and coarse control voltage generating means for generating and providing to said oscillator means a coarse control voltage corresponding to a desired output frequency of said clock recovery network.
Claim 2
Dependent Claim
125 words
A clock recovery network for receiving an input data stream having a symbol clock rate and providing as an output a clock signal synchronized with said input data stream, said network comprising: oscillator means for receiving said input data stream and providing at its output a clock signal synchronized with said input data stream, said oscillator means being synchronized to said input data stream by means of synchronizing pulses generated from said input data stream, the free-running frequency of said oscillator means in the absence of said synchronizing pulses being determined by a coarse control voltage; and coarse control voltage generating means for generating and providing to said oscillator means a coarse control voltage corresponding to a desired output frequency of said clock recovery network.
Claim 3
Dependent Claim
34 words
A clock recovery network as defined in claim 1, wherein said oscillator is a synchronized voltage controlled oscillator for receiving a synchronization signal and providing a digital output clock synchronized to said synchronization signal.
Claim 4
Dependent Claim
32 words
A clock recovery network as defined in claim 2, wherein said oscillator means includes a pulse forming network for receiving said input data stream and generating therefrom a stream of synchronization pulses.
Claim 5
Dependent Claim
29 words
A clock recovery network as defined in claim 3, wherein the output of said oscillator means is fed back and combined with the output of said pulse forming network.
Claim 6
Dependent Claim
25 words
A clock recovery network as defined in claim 1, wherein said coarse control voltage corresponds to approximately twice the frequency of said symbol clock rate.
Claim 7
Dependent Claim
32 words
A clock recovery network as defined in claim 1, wherein said oscillator means includes at least one variable resistance element the resistance of which determines the free-running frequency of said oscillator means.
Claim 8
Dependent Claim
27 words
A clock recovery network as defined in claim 6, wherein said at least one variable resistance element comprises a plurality of variable resistance elements connected in parallel.
Claim 9
Dependent Claim
24 words
A clock recovery network as defined in claims 6 or 7, wherein said at least one variable resistance element comprises a field effect transistor.
Claim 10
Dependent Claim
51 words
A clock recovery network as defined in claim 1, wherein said coarse control voltage generating means comprises a frequency-to-voltage converter for receiving an input signal and providing a coarse control voltage corresponding to the frequency of said input signal, said frequency-to-voltage converter receiving said input data stream as its input signal.
Claim 11
Dependent Claim
46 words
A clock recovery network as defined in claim 9, further comprising integrator means coupled between said frequency-to-voltage converter and said oscillator means, whereby said oscillator means will continue to operate at said desired output frequency even during the absence of an output from said frequency-to-voltage converter.
References Cited (Backward Citations)
US3792361A
Cited
US4151485A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-06-15 | 1984-12-15 | 1985-06-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-06-15 | 1988-12-15 | 1989-06-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-06-15 | 1992-12-15 | 1993-06-16 | $7700.00 | Window Closed / Lapsed |