Patent US4747114A successfully refreshed from Google Patents.
US4747114A
Expired / Lapsed
US
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Modem clock with automatic gain control
Assignee: Racal Data Communications Inc
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Filing: 1984-09-24
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Granted: 1988-05-24
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Expires: 2004-09-24
Abstract
Abstract A modem receiver having a timing recovery circuit is disclosed. The timing recovery circuit includes circuitry for extracting timing information, multiplication circuitry responsive to the timing information for providing a clock envelope signal and processing circuitry for controlling the gain of the clock envelope signal as a function of the average power of the clock envelope signal.
Inventors
- 👤 Aldo A. Martinez
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 11:24
CPC Classifications
H; H04; H04L; H04L7/00; H04L7/02; H04L7/027; H04L7/0278; H04L7/04; H04L7/041; H04L7/046
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
77 words
A modem clock recovery system comprising: a comb filter responsive to a data modulated received signal for providing a comb filter output; resonator means responsive to said comb filter output for providing Nyquist band edge components: means responsive to said Nyquist band edge components for providing a reference signal having a clock timing component; and gain control means responsive to said reference signal for adaptively controlling the gain of said reference signal having a clock timing component.
Claim 2
Dependent Claim
77 words
A modem clock recovery system comprising: a comb filter responsive to a data modulated received signal for providing a comb filter output; resonator means responsive to said comb filter output for providing Nyquist band edge components: means responsive to said Nyquist band edge components for providing a reference signal having a clock timing component; and gain control means responsive to said reference signal for adaptively controlling the gain of said reference signal having a clock timing component.
Claim 3
Dependent Claim
56 words
The clock recovery system of claim 1 wherein said gain control means comprises: means for determining the average power of said reference signal, and for providing a gain control factor as a function of said average power; and means for controlling the level of said Nyquist band edge components in response to said gain control factor.
Claim 4
Dependent Claim
25 words
The clock recovery system of claim 2 wherein said level controlling means comprises means for multiplying said comb filter output by said gain control factor.
Claim 5
Dependent Claim
26 words
The clock recovery system of claim 2 wherein said level controlling means comprises means for multiplying said Nyquist band edge components by said gain control factor.
Claim 6
Dependent Claim
40 words
The clock recovery system of claim 2 wherein said average power determining means includes a look-up table with predetermined values and from which the gain control factor is selected as a function of said average power of said reference signal.
Claim 7
Dependent Claim
17 words
The clock recovery system of claim 5 wherein said look-up table includes at least two predetermined values.
Claim 8
Dependent Claim
24 words
The clock recovery system of claim 2 wherein said average power determining means computes the gain control factor in accordance with a predetermined equation.
Claim 9
Dependent Claim
90 words
A gain controlled clock recovery system for a modem comprising: means for extracting timing information from a data modulated received signal that includes said timing information; means responsive to said timing information for providing a reference signal having a clock timing component; means for determining the average power of said reference signal, and for providing a gain control factor as a function of said average power; and means for multiplying said reference signal by said gain control factor to provide a gain controlled reference signal having a clock timing component.
Claim 10
Dependent Claim
90 words
A gain controlled clock recovery system for a modem comprising: means for extracting timing information from a data modulated received signal that includes said timing information; means responsive to said timing information for providing a reference signal having a clock timing component; means for determining the average power of said reference signal, and for providing a gain control factor as a function of said average power; and means for multiplying said reference signal by said gain control factor to provide a gain controlled reference signal having a clock timing component.
Claim 11
Dependent Claim
34 words
The clock recovery system of claim 8 wherein said reference signal comprises a series of samples and wherein said average power determining means determines said average power from a predetermined number of said samples.
Claim 12
Dependent Claim
84 words
The clock recovery system of claim 8 wherein said reference signal comprises a series of samples, and wherein said average power determining means determines said average power for the n th sample in accordance with the following recursive equation: P(n)=K.sub.1 P(n-1)+K.sub.2 B.sup.2 (n) where P(n) is the average power of the n th sample, P(n-1) is the average power of the prior sample, K 1 and K 2 are constants which are less than unity, and B(n) is the n th sampled reference signal.
Claim 13
Dependent Claim
40 words
The clock recovery system of claim 8 wherein said average power determining means includes a look-up table with predetermined values and from which the gain control factor is selected as a function of said average power of said reference signal.
Claim 14
Dependent Claim
17 words
The clock recovery system of claim 11 wherein said look-up table includes at least two predetermined values.
Claim 15
Dependent Claim
24 words
The clock recovery system of claim 8 wherein said average power determining means computes the gain control factor in accordance with a predetermined equation.
Claim 16
Dependent Claim
91 words
The clock recovery system of claim 8 wherein said reference signal comprises a series of samples and wherein said average power determining means computes the gain control factor for the n th sample in accordance with the following recursive equation: G(n)=K.sub.3 G(n-1)=K.sub.4 D(n) where G(n) is the gain control factor for the n th sample, G(n-1) is the gain control factor for the prior sample, K 3 and K 4 are constants, and D(n) is the difference between a reference power level and the average power of the n th sample.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-05-24 | 1991-11-23 | 1992-05-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-24 | 1995-11-23 | 1996-05-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-24 | 1999-11-23 | 2000-05-24 | $7700.00 | Window Closed / Lapsed |