US3939341A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Phase-locked optical homodyne receiver
Assignee: Raytheon Co
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Filing: 1975-04-02
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Granted: 1976-02-17
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Expires: 1995-04-02
Abstract
Abstract An improved homodyne receiver for use in wideband optical communications systems is disclosed. The invention provides phase-locked homodyne reception of non-suppressed carrier or suppressed carrier input signals. Novel means are provided in the receiver for generating an error signal to provide phase-locked operation in the presence of noise and frequency excursions of the received signal.
Inventors
- 👤 Ross E. Graves
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:16
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/60; H04B10/61; H03; H03D; H03D1/00; H03D1/22; H03D1/2281; H04B10/63
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
155 words
A phase-locked optical homodyne receiver comprising, in combination: means for receiving an optical input signal, said input signal being characterized by a carrier frequency and information-containing modulation components; controllable means for generating an optical local oscillator signal having substantially the same frequency as said carrier frequency; modulating means for phase modulating one of said signals with a reference modulation signal having a frequency which is substantially low compared to said carrier frequency; means for combining said phase-modulated signal with the other of said signals; means for optically detecting said combined signals; means for deriving an output signal from said optically detected signals; and means for synchronously detecting said output signal by providing an error signal responsive to said reference modulation signal at said reference frequency and a portion of said output signal, said error signal coupled to said local oscillator signal generating means to maintain said local oscillator signal and said carrier in phase synchronism.
Claim 2
Dependent Claim
155 words
A phase-locked optical homodyne receiver comprising, in combination: means for receiving an optical input signal, said input signal being characterized by a carrier frequency and information-containing modulation components; controllable means for generating an optical local oscillator signal having substantially the same frequency as said carrier frequency; modulating means for phase modulating one of said signals with a reference modulation signal having a frequency which is substantially low compared to said carrier frequency; means for combining said phase-modulated signal with the other of said signals; means for optically detecting said combined signals; means for deriving an output signal from said optically detected signals; and means for synchronously detecting said output signal by providing an error signal responsive to said reference modulation signal at said reference frequency and a portion of said output signal, said error signal coupled to said local oscillator signal generating means to maintain said local oscillator signal and said carrier in phase synchronism.
Claim 3
Dependent Claim
153 words
A phase-locked optical homodyne receiver comprising, in combination: means for receiving an optical input signal, said signal being characterized by a carrier and at least one sideband; controllable means for generating an optical local oscillator signal having substantially the same frequency as said carrier; modulating means for phase modulating said input signal with a reference modulation signal having a frequency which is substantially low compared to said carrier frequency; means for combining the phase modulated input signal and said local oscillator signal; means for optically detecting said combined signals; means for deriving an output signal from said optically detected signals; and means for synchronously detecting said output signal by providing an error signal responsive to said reference modulation signal at said reference frequency and a portion of said output signal, said error signal coupled to said local oscillator signal generating means to maintain said local oscillator signal and said carrier in phase synchronism.
Claim 4
Dependent Claim
153 words
A phase-locked optical homodyne receiver comprising, in combination: means for receiving an optical input signal, said signal being characterized by a carrier and at least one sideband; controllable means for generating an optical local oscillator signal having substantially the same frequency as said carrier; modulating means for phase modulating said input signal with a reference modulation signal having a frequency which is substantially low compared to said carrier frequency; means for combining the phase modulated input signal and said local oscillator signal; means for optically detecting said combined signals; means for deriving an output signal from said optically detected signals; and means for synchronously detecting said output signal by providing an error signal responsive to said reference modulation signal at said reference frequency and a portion of said output signal, said error signal coupled to said local oscillator signal generating means to maintain said local oscillator signal and said carrier in phase synchronism.
Claim 5
Dependent Claim
18 words
The receiver according to claim 2 wherein said local oscillator signal generating means comprises a tunable laser oscillator.
Claim 6
Dependent Claim
19 words
The receiver according to claim 2 wherein said modulating means includes a modulation oscillator and an electro-optic phase modulator.
Claim 7
Dependent Claim
14 words
The receiver according to claim 2 wherein said combining means comprises a beam-spltting mirror.
Claim 8
Dependent Claim
17 words
The receiver according to claim 2 wherein said means for deriving an output signal comprises an amplifier.
Claim 9
Dependent Claim
171 words
A phase-locked optical homodyne receiver comprising, in combination: means for receiving an optical input signal, said signal characterized by a suppressed carrier of a given frequency and at least one sideband; means for phase modulating said input signal with a reference modulation signal having a frequency which is substantially low with respect to said given frequency; controllable means for generating an optical local oscillator signal having substantially the same frequency as said given frequency; means for combining said phase-modulated input signal with said local oscillator signal; means for optically detecting said combined signals; means for deriving an output signal from said optically detected signals; means for envelope detecting a portion of said video output signal; and means for synchronously detecting said output signal by providing an error signal responsive to said reference modulation signal at said reference frequency and the output signal of said envelope detecting means, said error signal coupled to said local oscillator signal generating means to maintain said local oscillator signal and said suppressed carrier in phase synchronism.
Claim 10
Dependent Claim
171 words
A phase-locked optical homodyne receiver comprising, in combination: means for receiving an optical input signal, said signal characterized by a suppressed carrier of a given frequency and at least one sideband; means for phase modulating said input signal with a reference modulation signal having a frequency which is substantially low with respect to said given frequency; controllable means for generating an optical local oscillator signal having substantially the same frequency as said given frequency; means for combining said phase-modulated input signal with said local oscillator signal; means for optically detecting said combined signals; means for deriving an output signal from said optically detected signals; means for envelope detecting a portion of said video output signal; and means for synchronously detecting said output signal by providing an error signal responsive to said reference modulation signal at said reference frequency and the output signal of said envelope detecting means, said error signal coupled to said local oscillator signal generating means to maintain said local oscillator signal and said suppressed carrier in phase synchronism.
Claim 11
Dependent Claim
18 words
The receiver according to claim 7 wherein said local oscillator signal generating means comprises a tunable laser oscillator.
Claim 12
Dependent Claim
19 words
The receiver according to claim 7 wherein said modulating means includes a modulation oscillator and an electro-optic phase modulator.
Claim 13
Dependent Claim
14 words
The receiver according to claim 7 wherein said combining means comprises a beam-splitting mirror.
Claim 14
Dependent Claim
18 words
The receiver according to claim 7 wherein said means for deriving a video output signal comprises an amplifier.
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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) | 1979-02-16 | 1979-08-18 | 1980-02-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-02-16 | 1983-08-18 | 1984-02-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-02-16 | 1987-08-18 | 1988-02-17 | $7700.00 | Window Closed / Lapsed |