US4003060A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Direction finding receiver
Assignee: Federal Communications Commission
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Filing: 1975-02-26
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Granted: 1977-01-11
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Expires: 1995-02-26
Abstract
Abstract A direction finding receiver contained in a hand held portable housing with a ferrite rod antenna mounted in and protruding through the housing so that when the antenna axis points to the radio frequency signal source to be direction found, a null is obtained in the signal level. The antenna is coupled to the receiver circuit which comprises a broadband fixed tuned radio frequency amplifier having low sensitivity, a modulation oscillator used to modulate the broadband fixed tuned rf amplifier by tone injection when a steady carrier is present, a demodulator for demodulating the rf signal, and an audio amplifier for amplifying the demodulated signal.
Inventors
- 👤 Fred L. Broce
- 👤 William F. Bentley, Jr.
- 👤 William L. Kilpatrick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 09:57
CPC Classifications
G; G01; G01S; G01S3/00; G01S3/02; G01S3/14; G01S3/38
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
138 words
In a hand held portable direction finding receiver contained in a metal rectangular housing having an affixed ferrite rod antenna in said housing coupled to receiving circuitry, the improvement in said receiving circuitry comprising a fixed and predesigned frequency tuned-input means and identically tuned-output means connected to a first dual gate protected MOS FET radio frequency amplifier having capability of operating at preselected rolloff points yielding a frequency bandwidth of at least 2% about said pre-designed frequency of said tuned-input, tuned-output means allowing simultaneous operation on more than one radio communication channel with no frequency tuning adjustments, said tuned-input means being connected to a first gate of said first FET, said tuned-output means connected to a drain of said first FET, and means for internally modulating a received signal connected to a second gate of said first FET.
Claim 2
Dependent Claim
138 words
In a hand held portable direction finding receiver contained in a metal rectangular housing having an affixed ferrite rod antenna in said housing coupled to receiving circuitry, the improvement in said receiving circuitry comprising a fixed and predesigned frequency tuned-input means and identically tuned-output means connected to a first dual gate protected MOS FET radio frequency amplifier having capability of operating at preselected rolloff points yielding a frequency bandwidth of at least 2% about said pre-designed frequency of said tuned-input, tuned-output means allowing simultaneous operation on more than one radio communication channel with no frequency tuning adjustments, said tuned-input means being connected to a first gate of said first FET, said tuned-output means connected to a drain of said first FET, and means for internally modulating a received signal connected to a second gate of said first FET.
Claim 3
Dependent Claim
29 words
The apparatus of claim 1 wherein said means comprises a Twin T feedback oscillator and said oscillator having an output connected to said second gate of said first FET.
Claim 4
Dependent Claim
41 words
The apparatus of claim 2 wherein the improvement further comprises an N Channel second FET capacitively coupled to the output of said first FET to demodulate a signal from said first FET and audio rectification means for rectifying said demodulated signal.
Claim 5
Dependent Claim
29 words
The apparatus of claim 3 wherein audio rectification means comprises an operational amplifier driving a pair of low current silicon NPN-PNP transistors in a complimentary pair power output stage.
Claim 6
Dependent Claim
31 words
The apparatus of claim 4 wherein the improvement further comprises a gain and impedance matching low current silicon NPN transistor coupled between said operational amplifier and said pair of NPN-PNP transistors.
Claim 7
Dependent Claim
41 words
The apparatus of claim 1 wherein the improvement further comprises an N Channel second FET capacitively coupled to the output of said first FET to demodulate a signal from said first FET and audio rectification means for rectifying said demodulated signal.
Claim 8
Dependent Claim
29 words
The apparatus of claim 6 wherein audio rectification means comprises an operational amplifier driving a pair of low current silicon NPN-PNP transistors in a complimentary pair power output stage.
Claim 9
Dependent Claim
31 words
The apparatus of claim 7 wherein the improvement further comprises a gain and impedance matching low current silicon NPN transistor coupled between said operational amplifier and said pair of NPN-PNP transistors.
References Cited (Backward Citations)
US3115635A
Cited
US3323129A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-01-11 | 1980-07-12 | 1981-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-11 | 1984-07-12 | 1985-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-11 | 1988-07-12 | 1989-01-11 | $7700.00 | Window Closed / Lapsed |