US3699463A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Error reduction in communication systems
Assignee: AT&T Inc
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Filing: 1970-11-30
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Granted: 1972-10-17
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Expires: 1990-11-30
Abstract
Abstract The output from a phase detector is a function of both the amplitude and phase of the input signals. Error, due to spurious amplitude modulation of the angular modulated carrier signal, is minimized by dividing the phase detector output signal by a reference signal whose instantaneous amplitude is proportional to the amplitudes of the phase detector input signals. A phase modulated, optical communication system is described. The principles of the invention are also applicable to amplitude and frequency modulated signal systems.
Inventors
- 👤 Julian Stone
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:07
CPC Classifications
H; H03; H03D; H03D1/00; H03D1/14; H03D1/20; G; G02; G02F; G02F1/00; G02F1/01; G02F1/0121; G02F2/00; H03D3/00; H03D3/007; H03D5/00; H04; H04B; H04B10/00; H04B10/50; H04B10/516; H04B10/548; H04L; H04L27/00; H04L27/32; H04L27/34; H04L27/38; G02F1/03; G02F1/21; G02F1/213
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
77 words
A modulation detection system comprising: means for dividing a received modulated signal into two components; means for coupling one of said components to a modulation detector; means for coupling the other component to a reference generator for generating a reference signal whose amplitude varies proportionally with the amplitude of the carrier of the modulated signal component coupled to said modulation detector; and means for dividing the output signal derived from said modulation detector by said reference signal.
Claim 2
Dependent Claim
77 words
A modulation detection system comprising: means for dividing a received modulated signal into two components; means for coupling one of said components to a modulation detector; means for coupling the other component to a reference generator for generating a reference signal whose amplitude varies proportionally with the amplitude of the carrier of the modulated signal component coupled to said modulation detector; and means for dividing the output signal derived from said modulation detector by said reference signal.
Claim 3
Dependent Claim
76 words
A frequency-shift-keyed modulation detector comprising: a signal divider for dividing a frequency-shift-keyed modulated signal into two components; means for coupling one of said components to a frequency separating filter for separating signals of different frequencies; separate means for amplitude detecting said different frequency signals; means for coupling the other of said components to another amplitude detector to form a reference signal; and means for dividing each of said detected different frequency signals by said reference signal.
Claim 4
Dependent Claim
76 words
A frequency-shift-keyed modulation detector comprising: a signal divider for dividing a frequency-shift-keyed modulated signal into two components; means for coupling one of said components to a frequency separating filter for separating signals of different frequencies; separate means for amplitude detecting said different frequency signals; means for coupling the other of said components to another amplitude detector to form a reference signal; and means for dividing each of said detected different frequency signals by said reference signal.
Claim 5
Dependent Claim
69 words
An amplitude modulation detection circuit comprising: an amplitude detector; means for generating a reference signal whose amplitude varies as a function of the amplitude of the carrier signal applied to said amplitude detector comprising: means for isolating the direct current component of the output signal produced by said detector; and means for dividing the modulation component of signal derived from said detector by said direct current component of signal.
Claim 6
Dependent Claim
69 words
An amplitude modulation detection circuit comprising: an amplitude detector; means for generating a reference signal whose amplitude varies as a function of the amplitude of the carrier signal applied to said amplitude detector comprising: means for isolating the direct current component of the output signal produced by said detector; and means for dividing the modulation component of signal derived from said detector by said direct current component of signal.
Claim 7
Dependent Claim
90 words
The circuit according to claim 3 wherein said detector is a diode; and wherein the output from said diode is coupled to two parallel wavepaths; filtering means in the first of said wavepaths for transmitting frequency components of wave energy greater than a specified frequency; filtering means in the second of said wavepaths for transmitting frequency components of wave energy less than said specified frequency; and means for dividing the transmitted components of wave energy in said first wavepath by the transmitted components of wave energy in said second wavepath.
Claim 8
Dependent Claim
25 words
The modulation detector according to claim 3 including signal shaping means in said second wavepath between said reference signal generating means and said signal divider.
Claim 9
Dependent Claim
29 words
The system according to claim 1 wherein said modulation detector is an optical phase detector; and wherein said means for generating a reference signal is an optical amplitude deTector.
Claim 10
Dependent Claim
39 words
The modulation detection system according to claim 1 wherein first and second wavepaths couple, respectively, said detector and said reference signal generating means to said dividing means; and wherein delay equalization means are included in one of said wavepaths.
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) | 1975-10-17 | 1976-04-17 | 1976-10-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-17 | 1980-04-17 | 1980-10-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-17 | 1984-04-17 | 1984-10-17 | $7700.00 | Window Closed / Lapsed |