US3766478A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Backscatter reduction apparatus
Assignee: United States Department of the Navy
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Filing: 1972-09-08
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Granted: 1973-10-16
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Expires: 1992-09-08
Abstract
Abstract Apparatus for reducing F1/F1 repeater backscatter without significantly changing the desired received signal. A replica signal of the desired transmitted signal on center frequency F1 is transmitted on center frequency F2 to produce a received signal on frequency F2 which is predominantly due to backscatter from the transmission on F2 and which has a very high correlation with the backscatter from the desired transmitted signal on F1. The characteristics of the backscatter on F2 are accurately measured and then correlated to the backscatter on F1 whereby it can be reduced or minimized with relatively minor change of the desired received signal.
Inventors
- 👤 R Lowry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:18
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/14; H04B7/15; H04B7/185; H04B7/1853; H04B7/18539; H04B7/18543; H04B7/22
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
174 words
Apparatus for attenuating backscatter from F1/F1 repeaters and comprising: antenna means for receiving desired signals and corresponding backscatter on center frequency F1 and replica signals of said desired signals on center frequency F2; means for separating said desired signals and corresponding backscatter on F1 from said replica signals on F2; means for producing from said replica signal after said separation an output on F2 substantially equal to said backscatter on F1; means for subtracting said output on F2 from said desired signals and backscatter on F1 to produce a resultant output substantially free from backscatter; delay means for delaying said resultant output a selectively predetermined time period; F1/F1 repeater means for isolating desired signals to be transmitted on F1 from the delayed resultant signal; means for producing said replica signals on F2; means for adding said replica signals on F2 to said desired signals to be transmitted on F1 from said F1/F1 repeater means to produce a desired resultant signal to be transmitted; and, antenna means for transmitting said resultant signal to be transmitted.
Claim 2
Dependent Claim
174 words
Apparatus for attenuating backscatter from F1/F1 repeaters and comprising: antenna means for receiving desired signals and corresponding backscatter on center frequency F1 and replica signals of said desired signals on center frequency F2; means for separating said desired signals and corresponding backscatter on F1 from said replica signals on F2; means for producing from said replica signal after said separation an output on F2 substantially equal to said backscatter on F1; means for subtracting said output on F2 from said desired signals and backscatter on F1 to produce a resultant output substantially free from backscatter; delay means for delaying said resultant output a selectively predetermined time period; F1/F1 repeater means for isolating desired signals to be transmitted on F1 from the delayed resultant signal; means for producing said replica signals on F2; means for adding said replica signals on F2 to said desired signals to be transmitted on F1 from said F1/F1 repeater means to produce a desired resultant signal to be transmitted; and, antenna means for transmitting said resultant signal to be transmitted.
Claim 3
Dependent Claim
25 words
The apparatus of claim 1 wherein said means for separating said desired signals and backscatter from said replica signals comprises a frequency domain filter circuit.
Claim 4
Dependent Claim
18 words
The apparatus of claim 1 wherein said means for producing said output on F2 comprises multiplexer integrator means.
Claim 5
Dependent Claim
29 words
The apparatus of claim 1 wherein said means for subtracting said output signal on F2 from said desired signals and backscatter on F1 comprises a frequency domain trap circuit.
Claim 6
Dependent Claim
15 words
The apparatus of claim 1 wherein said F1/F1 repeater means comprises an injection locked oscillator.
Claim 7
Dependent Claim
47 words
The apparatus of claim 1 wherein said means for producing said replica signals comprises an F2 offset frequency reference source and a mixer means responsive to the output of said source and to the output of said F1/F1 repeater means to produce said replica signals on F2.
Claim 8
Dependent Claim
16 words
The apparatus of claim 1 wherein said means for adding said signals comprises a summing circuit.
References Cited (Backward Citations)
US3696429A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-15 | 1977-04-16 | 1977-10-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-15 | 1981-04-16 | 1981-10-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-15 | 1985-04-16 | 1985-10-16 | $7700.00 | Window Closed / Lapsed |