US3883872A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for interference signal nulling by polarization adjustment
Assignee: National Aeronautics and Space Administration
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Filing: 1973-06-28
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Granted: 1975-05-13
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Expires: 1993-06-28
Abstract
Abstract A receiving system for automatically selecting a desired one of two approximately orthogonally polarized signals occupying the same bandwidth, is disclosed. Received signals are provided by any orthomode antenna system at a pair of output ports, i.e., right hand and left hand circular polarizations or two linear polarizations. The received signals are then applied to the inputs of a hybrid junction to produce sum and difference signals. The resulting sum signal at one output port comprises components of the undesired one of two orthogonally polarized signals and is used to coherently detect and dynamically balance out the undesired signal components that are included at the difference signal port. The desired one of two orthogonally polarized signals is thereby provided at the difference port of the hybrid junction. Feedback loops are used to effect dynamic balancing.
Inventors
- 👤 James C Administrator Fletcher
- 👤 John E Ohlson
- 👤 William F Williams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:44
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/002
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
165 words
A receiving system for selecting a desired one of two orthogonally polarized signals occupying the same bandwidth, said receiving system including: an orthomode antenna having two output ports at which components of said two orthogonally polarized signals are provided; a hybrid junction having a pair of input terminals for respectively receiving signals from the two output ports of said orthomode antenna, and sum and difference output terminals at which are respectively provided a sum signal representing the sum of the signals applied to said hybrid junction and a difference signal representing the difference of the signals applied to said hybrid junction; detection means for coherently detecting the presence of components of the undesired one of said two orthogonally polarized signals that may appear in said difference signal, said detection means providing error signals; and adjustment means responsive to said error signals for automatically nulling said components of said undesired signal to have said difference signal continually represent the desired one of said orthogonally polarized signals.
Claim 2
Dependent Claim
165 words
A receiving system for selecting a desired one of two orthogonally polarized signals occupying the same bandwidth, said receiving system including: an orthomode antenna having two output ports at which components of said two orthogonally polarized signals are provided; a hybrid junction having a pair of input terminals for respectively receiving signals from the two output ports of said orthomode antenna, and sum and difference output terminals at which are respectively provided a sum signal representing the sum of the signals applied to said hybrid junction and a difference signal representing the difference of the signals applied to said hybrid junction; detection means for coherently detecting the presence of components of the undesired one of said two orthogonally polarized signals that may appear in said difference signal, said detection means providing error signals; and adjustment means responsive to said error signals for automatically nulling said components of said undesired signal to have said difference signal continually represent the desired one of said orthogonally polarized signals.
Claim 3
Dependent Claim
53 words
The system defined by claim 1, wherein said adjustment means includes a variable phase control circuit and a variable gain control circuit, which are connected to respectively adjust the phase and gain of components of said undesired signals that are applied from one output port to said orthomode antenna to said hybrid junction.
Claim 4
Dependent Claim
46 words
The system defined by claim 2, said adjustment means further including first and second servo control circuits each connected to receive error signals from said detection means for respectively operating said variable phase and gain control circuits in accordance with error signals from said detection means.
Claim 5
Dependent Claim
18 words
The system defined by claim 2 wherein said variable phase and gain control circuits are connected in series.
Claim 6
Dependent Claim
90 words
The system defined by claim 1, said detection meams being connected to the difference output terminal of said hybriD junction, components of said undesired signal including a phase component and an amplitude component, said detecting means including: first means for providing a first error signal representative of the phase component of said components of said undesired signal; and means for providing a second error signal representative of the amplitude components of said components of said undesired signal, wherein said first and second error signals are applied to said adjustment means.
Claim 7
Dependent Claim
43 words
The system defined by claim 5, said first means including means for coherently detecting said phase component of said components of said undesired signal and said second means including means for coherently detecting said amplitude component of said components of said undesired signal.
Claim 8
Dependent Claim
59 words
The system defined by claim 1 further including: frequency control means for heterodyning the output signals provided at the two output ports of said orthomode antenna to a predetermined intermediate frequency; and means connected to receive said sum signals from said hybrid junction for providing phase lock error signals to said frequency control means for maintaining said predetermined frequency.
Claim 9
Dependent Claim
50 words
The system defined by claim 7, said frequency control means including: a voltage controlled oscillator connected to receive said phase lock error signals; and a pair of mixer circuits each connected to a different one of said two output ports of said orthomode antenna and to said voltage controlled oscillator.
Claim 10
Dependent Claim
90 words
The system defined by claim 2, said detection means being connected to the difference output terminal of said hybrid junction, components of said undesired signal including a phase component and an amplitude component, said detecting means including: first means for providing a first error signal representative of the phase component of said components of said undesired signal; and means for providing a second error signal representative of the amplitude component of said components of said undesired signal, wherein said first and second error signals are applied to said adjustment means.
Claim 11
Dependent Claim
59 words
The system defined by claim 9 further including: frequency control means for heterodyning the output signals provided at the two output ports of said orthomode antenna to a predetermined intermediate frequency; and means connected to receive said sum signals from said hybrid junction for providing phase lock error signals to said frequency control means for maintaining said predetermined frequency.
Claim 12
Dependent Claim
46 words
The system defined by claim 10, said adjustment means further including first and second servo control circuits each connected to receive error signals from said detection means for respectively operating said variable phase and gain control circuits in accordance with error signals from said detection means.
Claim 13
Dependent Claim
43 words
The system defined by claim 11, said first means including means for coherently detecting said phase component of said components of said undesired signal and said second means including means for coherently detecting said amplitude component of said components of said undesired signal.
Claim 14
Dependent Claim
18 words
The system defined by claim 12 wherein said variable phase and gain control circuits are connected in series.
Claim 15
Dependent Claim
50 words
The system defined by claim 13, said frequency control means including: a voltage controlled oscillator connected to receive said phase lock error signals; and a pair of mixer circuits each connected to a different one of said two output ports of said orthomode antenna and to said voltage controlled oscillator.
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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) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |