Patent US3887923A successfully refreshed from Google Patents.
US3887923A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Radio-frequency holography
Assignee: United States Department of the Navy
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Filing: 1973-06-26
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Granted: 1975-06-03
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Expires: 1993-06-26
Abstract
Abstract A passive radio direction finder monitors wavefronts across an aperture, produces a radio-frequency hologram, and numerically reconstructs the hologram. The direction finder consists of an array of antennas to sample the phase of incoming wavefronts, a plurality of mixers separately connected to individual antennas, a phase lock loop or bandpass limiter connected between any individual antenna and an input of each mixer to provide a mixer reference signal, a multi-channel analog to digital converter attached to the output of each mixer, and a digital computer programmed to make fast Fourier transform calculations. In lieu of the plurality of antennas and mixers, a moving probe antenna and single mixer may be used if a sample and hold circuit is added to the phase lock circuit to provide a reference signal.
Inventors
- 👤 Charles E Hendrix
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:25
CPC Classifications
G; G01; G01S; G01S3/00; G01S3/02; G01S3/14; G01S3/46; G01S5/00; G01S5/02; G01S5/04
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
235 words
PASSIVE PASSAVE RADIO DIRECTION FINDER FOR PRODUCING A RADIO FREQUENCY HOLOGRAM AND NUMERICALLY RECONSTRUCTING THE HOLOGRAM SAID FINDER COMPRISING; A PLURALITY OF FIXED ANTENNA ELEMENTS CLOSELY SPACED TO FORM A LINEAR ARRAY HAVING A PREDETERMINED RECEIVING APERTURE FOR INDIVIDUALLY SAMPLING THE PHASE OF AN INCOMING WAVE FRONT AT DISCRETE POINTS ACROSS THE RECEIVING APERTURE; A PLURALITY OF MIXER ELEMENTS EACH SEPARATELY ELECTRICALLY COUPLED TO EACH OF SAID ANTENNA ELEMENTS FOR RECEIVING INDIVIDUAL ELECTRICAL SIGNALS; SELF CONTAINED REFERENCE SIGNAL MEANS ELECTRICALLY COUPLED TO RECEIVE A SIGNAL FROM ONE OF SAID ANTENNA ELEMENTS AND ELECTRICALLY COUPLED TO EACH OF SAID MIXER ELEMENTS FOR PROVIDING A SIGNAL OUTPUT THAT IS THE SAME FREQUENCY AS THE SIGNAL RECEIVED BY EACH OF SAID ANTENNA ELEMENTS; A MULTI-CHANNEL ANALOG-TO-DIGITAL CONVERTER ELECTRICALLY COUPLED TO EACH OF SAID MIXER ELEMENTS FOR RECEIVING DIRECT CURRENT SIGNAL VOLTAGES FROM SAID MIXER ELEMENTS THAT ARE PROPORTIONAL TO THE RELATIVE PHASE OF AN INCOMING WAVE FRONT AS IT IMPINGES EACH OF SAID ANTENNA ELEMENTS AND TO PROVIDE AN OUTPUT THAT IS A DIGITAL REPRESENTATIVE OF EACH DIRECT CURRENT VOLTAGE; AND A FAST Fourier transform digital computer coupled to said converter for transforming each signal received by each of said antenna elements into a signal representative of the angles of arrival as an incoming wave front impinges said antenna elements; whereby a radio-frequency hologram is constructed that is indicative of the direction of the target from said directionfinder.
Claim 2
Dependent Claim
235 words
PASSIVE PASSAVE RADIO DIRECTION FINDER FOR PRODUCING A RADIO FREQUENCY HOLOGRAM AND NUMERICALLY RECONSTRUCTING THE HOLOGRAM SAID FINDER COMPRISING; A PLURALITY OF FIXED ANTENNA ELEMENTS CLOSELY SPACED TO FORM A LINEAR ARRAY HAVING A PREDETERMINED RECEIVING APERTURE FOR INDIVIDUALLY SAMPLING THE PHASE OF AN INCOMING WAVE FRONT AT DISCRETE POINTS ACROSS THE RECEIVING APERTURE; A PLURALITY OF MIXER ELEMENTS EACH SEPARATELY ELECTRICALLY COUPLED TO EACH OF SAID ANTENNA ELEMENTS FOR RECEIVING INDIVIDUAL ELECTRICAL SIGNALS; SELF CONTAINED REFERENCE SIGNAL MEANS ELECTRICALLY COUPLED TO RECEIVE A SIGNAL FROM ONE OF SAID ANTENNA ELEMENTS AND ELECTRICALLY COUPLED TO EACH OF SAID MIXER ELEMENTS FOR PROVIDING A SIGNAL OUTPUT THAT IS THE SAME FREQUENCY AS THE SIGNAL RECEIVED BY EACH OF SAID ANTENNA ELEMENTS; A MULTI-CHANNEL ANALOG-TO-DIGITAL CONVERTER ELECTRICALLY COUPLED TO EACH OF SAID MIXER ELEMENTS FOR RECEIVING DIRECT CURRENT SIGNAL VOLTAGES FROM SAID MIXER ELEMENTS THAT ARE PROPORTIONAL TO THE RELATIVE PHASE OF AN INCOMING WAVE FRONT AS IT IMPINGES EACH OF SAID ANTENNA ELEMENTS AND TO PROVIDE AN OUTPUT THAT IS A DIGITAL REPRESENTATIVE OF EACH DIRECT CURRENT VOLTAGE; AND A FAST Fourier transform digital computer coupled to said converter for transforming each signal received by each of said antenna elements into a signal representative of the angles of arrival as an incoming wave front impinges said antenna elements; whereby a radio-frequency hologram is constructed that is indicative of the direction of the target from said directionfinder.
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) | 1978-06-02 | 1978-12-02 | 1979-06-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-02 | 1982-12-02 | 1983-06-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-02 | 1986-12-02 | 1987-06-03 | $7700.00 | Window Closed / Lapsed |