US3680125A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Angular modulation direction finding receiver
Assignee: TDK Micronas GmbH
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Filing: 1970-06-16
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Granted: 1972-07-25
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Expires: 1990-06-16
Abstract
Abstract An improved null-sensing direction finding receiver responsive to an angle modulated signal is disclosed. The receiver includes an omnidirectional antenna and a directional null antenna. The omnidirectional antenna output signal is down converted to encompass the modulated frequency spectrum and in turn is fed to a FMFB detector where the VCO therein closely follows the angle modulated signal. The null antenna output signal is down converted, as in the case of the omnidirectional antenna output signal and then is subjected to a second frequency conversion employing the output signal of the VCO of the FMFB detector as the local oscillator signal for the second frequency conversion. This results in an improved null-sensitivity in the order of the modulation index, since the null accuracy is a direct function of signal-to-noise ratio. A square law detector and low pass filter after the second frequency conversion provides a null detection process insensitive to random phase fluctuations of the input signals.
Inventors
- 👤 Bernard Cooper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:31
CPC Classifications
G; G01; G01S; G01S1/00; G01S1/02
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
123 words
A null-sensing direction finding receiver capable of direction finding on a source transmitting an angle modulated signal comprising: an omnidirectional antenna in communication with said source; first means coupled to said omnidirectional antenna capable of closely following the frequency of said angle modulated signal; a directional null antenna in communication with said source; second means coupled to said null antenna and said first means to recover a signal having an improved null-sensitivity; a square law detector coupled to said second means to operate on said signal having an improved null-sensitivity; and a low pass filter coupled to said detector to provide a resultant improved null-sensitivity output signal for said receiver which is insensitive to random phase fluctuations of said signal from said source.
Claim 2
Dependent Claim
123 words
A null-sensing direction finding receiver capable of direction finding on a source transmitting an angle modulated signal comprising: an omnidirectional antenna in communication with said source; first means coupled to said omnidirectional antenna capable of closely following the frequency of said angle modulated signal; a directional null antenna in communication with said source; second means coupled to said null antenna and said first means to recover a signal having an improved null-sensitivity; a square law detector coupled to said second means to operate on said signal having an improved null-sensitivity; and a low pass filter coupled to said detector to provide a resultant improved null-sensitivity output signal for said receiver which is insensitive to random phase fluctuations of said signal from said source.
Claim 3
Dependent Claim
81 words
A receiver according to claim 1, wherein said first means includes third means coupled to said omnidirectional antenna to convert said angle modulated signal received thereby to an intermediate frequency signal having a given center frequency and a bandwidth sufficient to encompass the modulated frequency spectrum of said angle modulated signal, and a frequency modulation feedback detector coupled to said third means, said detector including a voltage controlled oscillator whose output signal closely follows the frequency of said intermediate frequency signal.
Claim 4
Dependent Claim
72 words
A receiver according to claim 1, wherein said second means includes third means coupled to said null antenna to convert said angle modulated signal received thereby to an intermediate frequency signal having a given center frequency and a bandwidth sufficient to to encompass the modulated frequency spectrum of said angle modulated signal, and a mixer coupled to said third means and said first means to recover said signal having an improved null-sensitivity.
Claim 5
Dependent Claim
41 words
A receiver according to claim 1, wherein said first means includes a frequency modulation feedback detector coupled to said omnidirectional antenna, said feedback detector including a voltage controlled oscillator whose output signal closely follows the frequency of said angle modulated signal.
Claim 6
Dependent Claim
40 words
A receiver according to claim 4, wherein said second means includes a mixer coupled to said null antenna and said voltage controlled oscillator to provide said signal having an improved null-sensitivity as an input signal for said square law detector.
Claim 7
Dependent Claim
147 words
A receiver according to claim 1, wherein said first means includes third means coupled to said omnidirectional antenna to convert said angle modulated signal received thereby to a first intermediate frequency signal having a given center frequency and a bandwidth sufficient to encompass the modulated frequency spectrum of said angle modulated signal, and a frequency modulation feedback detector coupled to said third means, said feedback detector including a voltage controlled oscillator whose output signal closely follows the frequency of said first intermediate frequency signal; and said second means includes fourth means coupled to said null antenna to convert said angle modulated signal received thereby to a second intermediate frequency signal having said given frequency and said bandwidth, and a mixer coupled to said fourth means and said voltage controlled oscillator to provide said signal having an improved null-sensitivity as an input signal for said square law detector.
Claim 8
Dependent Claim
17 words
A receiver according to claim 6, wherein said third and fourth means include a common local oscillator.
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) | 1975-07-25 | 1976-01-24 | 1976-07-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-25 | 1980-01-24 | 1980-07-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-25 | 1984-01-24 | 1984-07-25 | $7700.00 | Window Closed / Lapsed |