US3975628A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical heterodyne receiver with phase or frequency lock
Assignee: Raytheon Co
•
Filing: 1975-04-02
•
Granted: 1976-08-17
•
Expires: 1995-04-02
Abstract
Abstract An improved optical heterodyne receiver is disclosed. Novel control circuitry is utilized in the receiver to provide compensation and tracking for undesired phase and frequency excursions of both the received and the local oscillator signals. An optical heterodyne receiver such as that disclosed is especially useful in optical communications systems having wideband variations in the frequency of the received signal caused by Doppler shifts and angle-modulated noise components.
Inventors
- 👤 Ross E. Graves
- 👤 Lyle S. Stokes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 17:18
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/60; G; G02; G02F; G02F2/00; G02F2/002; H03; H03D; H03D3/00; H03D5/00; H04B10/61; H04B10/64
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
157 words
An optical heterodyne receiver comprising, in combination: a tunable laser oscillator, said laser oscillator having an output and a control input; means for combining said laser oscillator output with a received optical input signal; an optical detector coupled to said combining means, said optical detector being adapted to provide an intermediate frequency signal representative of the difference between said laser oscillator output and said received input signal; a controllable r.f. oscillator having a reference signal output and a control input; comparison means for generating a wideband control signal representative of the difference between said intermediate frequency signal and said reference signal; first means for coupling a first component of said control signal to said control input of said laser oscillator; second means for coupling a second component of said control signal to said control input of said controllable r.f. oscillator; and r.f. detector means coupled to said comparison means for deriving an output signal from said receiver.
Claim 2
Dependent Claim
157 words
An optical heterodyne receiver comprising, in combination: a tunable laser oscillator, said laser oscillator having an output and a control input; means for combining said laser oscillator output with a received optical input signal; an optical detector coupled to said combining means, said optical detector being adapted to provide an intermediate frequency signal representative of the difference between said laser oscillator output and said received input signal; a controllable r.f. oscillator having a reference signal output and a control input; comparison means for generating a wideband control signal representative of the difference between said intermediate frequency signal and said reference signal; first means for coupling a first component of said control signal to said control input of said laser oscillator; second means for coupling a second component of said control signal to said control input of said controllable r.f. oscillator; and r.f. detector means coupled to said comparison means for deriving an output signal from said receiver.
Claim 3
Dependent Claim
15 words
The receiver according to claim 1 wherein said combining means comprise a beam splitting mirror.
Claim 4
Dependent Claim
14 words
The receiver according to claim 1 wherein said first means includes a lowpass filter.
Claim 5
Dependent Claim
14 words
The receiver according to claim 1 wherein said second means includes a highpass filter.
Claim 6
Dependent Claim
15 words
The receiver according to claim 1 wherein said comparison means comprises a first phase detector.
Claim 7
Dependent Claim
54 words
The receiver according to claim 5 wherein said r.f. detector comprises a second phase detector having a pair of inputs, one of said inputs being coupled to the input of said first phase detector and the other of said inputs being coupled through a phase shifter to the signal output of said controllable oscillator.
Claim 8
Dependent Claim
24 words
The receiver according to claim 1 wherein said comparison means comprises the serial combination of a mixer, an i.f. stage and a frequency discriminator.
Claim 9
Dependent Claim
14 words
The receiver according to claim 7 wherein said r.f. detector comprises an envelope detector.
Claim 10
Independent Claim
117 words
The method of phase locking an optical heterodyne receiver to an optical input signal comprising the ordered steps of: generating an optical local oscillator signal; combining said local oscillator signal with said input signal; optically mixing the combined signals to produce an intermediate frequency signal; generating a reference signal having a nominal frequency substantially equal to said intermediate frequency; comparing said reference and intermediate frequency signals to produce a control signal representative of phase differences between the compared signals; controlling the frequency of said local oscillator signal substantially in response to a first portion of said control signal; and controlling the frequency of said reference signal substantially in response to a second portion of said control signal.
Claim 11
Independent Claim
117 words
The method of phase locking an optical heterodyne receiver to an optical input signal comprising the ordered steps of: generating an optical local oscillator signal; combining said local oscillator signal with said input signal; optically mixing the combined signals to produce an intermediate frequency signal; generating a reference signal having a nominal frequency substantially equal to said intermediate frequency; comparing said reference and intermediate frequency signals to produce a control signal representative of phase differences between the compared signals; controlling the frequency of said local oscillator signal substantially in response to a first portion of said control signal; and controlling the frequency of said reference signal substantially in response to a second portion of said control signal.
Claim 12
Independent Claim
117 words
The method of frequency locking an optical heterodyne receiver to an optical input signal comprising the ordered steps of: generating an optical local oscillator signal; combining said local oscillator signal with said input signal; optically mixing the combined signals to produce a first intermediate frequency signal; generating a reference signal; mixing said first intermediate frequency signal and said reference signal to produce a second intermediate frequency signal; frequency discriminating said second intermediate frequency signal to produce a control signal; controlling the frequency of said local oscillator signal substantially in response to a first portion of said control signal; and controlling the frequency of said reference signal substantially in response to a second portion of said control signal.
Claim 13
Independent Claim
117 words
The method of frequency locking an optical heterodyne receiver to an optical input signal comprising the ordered steps of: generating an optical local oscillator signal; combining said local oscillator signal with said input signal; optically mixing the combined signals to produce a first intermediate frequency signal; generating a reference signal; mixing said first intermediate frequency signal and said reference signal to produce a second intermediate frequency signal; frequency discriminating said second intermediate frequency signal to produce a control signal; controlling the frequency of said local oscillator signal substantially in response to a first portion of said control signal; and controlling the frequency of said reference signal substantially in response to a second portion of said control signal.
References Cited (Backward Citations)
US3471803A
Cited
US3573463A
Cited
US3654473A
Cited
US3586997A
Cited
US3571597A
Cited
US3695761A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-08-17 | 1980-02-16 | 1980-08-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-17 | 1984-02-16 | 1984-08-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-17 | 1988-02-16 | 1988-08-17 | $7700.00 | Window Closed / Lapsed |