US3887872A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Freeze circuit for aircraft radio navigation systems
Assignee: Bendix Corp
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Filing: 1973-12-05
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Granted: 1975-06-03
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Expires: 1993-12-05
Abstract
Abstract In aircraft, operation of on-board communications transmitter frequently interferes with radio navigation receiver. The invention provides switch means interposed between navigation receiver and course indicator or autopilot which, upon operation of transmitter, interrupts guidance signal from navigation receiver and holds input to course indicator or autopilot constant until navigation receiver has recovered from interference.
Inventors
- 👤 Claude A Sharpe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 05:39
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/38; H04B1/40; G; G01; G01S; G01S1/00; G01S1/02
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
236 words
In a radio navigation system, means for eliminating adverse effects of false guidance signals caused by intermittent transmissions from a nearby communications transmitter, said navigation system including a receiver tuned to a frequency within a band of frequencies assigned for navigation use and providing guidance signal output, and means utilizing said guidance signal output, said communications transmitter operating in a communications band of frequencies adjacent said navigation band of frequencies and being active to transmit or inactive depending upon the operation of a first switch means; comprising, second switch means interposed between said navigation receiver and said utilizing means, a first condition of said second switch means permitting application of guidance signal from said receiver to said utilizing means, a second condition of said second switch means interrupting application of said guidance signal to said utilizing means; means for storing said guidance signal during the time said second switch means is in said first condition and for applying said stored guidance signal to said utilizing means as a substitute for said guidance signal during the time said second switch means is in said second condition; and means controlled by said first switch means and controlling said second switch means to cause said second switch means to change from said first condition to said second condition whenever said transmitter is active and to revert said second switch means to said first condition whenever said transmitter is inactive.
Claim 2
Dependent Claim
236 words
In a radio navigation system, means for eliminating adverse effects of false guidance signals caused by intermittent transmissions from a nearby communications transmitter, said navigation system including a receiver tuned to a frequency within a band of frequencies assigned for navigation use and providing guidance signal output, and means utilizing said guidance signal output, said communications transmitter operating in a communications band of frequencies adjacent said navigation band of frequencies and being active to transmit or inactive depending upon the operation of a first switch means; comprising, second switch means interposed between said navigation receiver and said utilizing means, a first condition of said second switch means permitting application of guidance signal from said receiver to said utilizing means, a second condition of said second switch means interrupting application of said guidance signal to said utilizing means; means for storing said guidance signal during the time said second switch means is in said first condition and for applying said stored guidance signal to said utilizing means as a substitute for said guidance signal during the time said second switch means is in said second condition; and means controlled by said first switch means and controlling said second switch means to cause said second switch means to change from said first condition to said second condition whenever said transmitter is active and to revert said second switch means to said first condition whenever said transmitter is inactive.
Claim 3
Dependent Claim
236 words
In a radio navigation system, means for eliminating adverse effects of false guidance signals caused by intermittent transmissions from a nearby communications transmitter, said navigation system including a receiver tuned to a frequency within a band of frequencies assigned for navigation use and providing guidance signal output, and means utilizing said guidance signal output, said communications transmitter operating in a communications band of frequencies adjacent said navigation band of frequencies and being active to transmit or inactive depending upon the operation of a first switch means; comprising, second switch means interposed between said navigation receiver and said utilizing means, a first condition of said second switch means permitting application of guidance signal from said receiver to said utilizing means, a second condition of said second switch means interrupting application of said guidance signal to said utilizing means; means for storing said guidance signal during the time said second switch means is in said first condition and for applying said stored guidance signal to said utilizing means as a substitute for said guidance signal during the time said second switch means is in said second condition; and means controlled by said first switch means and controlling said second switch means to cause said second switch means to change from said first condition to said second condition whenever said transmitter is active and to revert said second switch means to said first condition whenever said transmitter is inactive.
Claim 4
Dependent Claim
236 words
In a radio navigation system, means for eliminating adverse effects of false guidance signals caused by intermittent transmissions from a nearby communications transmitter, said navigation system including a receiver tuned to a frequency within a band of frequencies assigned for navigation use and providing guidance signal output, and means utilizing said guidance signal output, said communications transmitter operating in a communications band of frequencies adjacent said navigation band of frequencies and being active to transmit or inactive depending upon the operation of a first switch means; comprising, second switch means interposed between said navigation receiver and said utilizing means, a first condition of said second switch means permitting application of guidance signal from said receiver to said utilizing means, a second condition of said second switch means interrupting application of said guidance signal to said utilizing means; means for storing said guidance signal during the time said second switch means is in said first condition and for applying said stored guidance signal to said utilizing means as a substitute for said guidance signal during the time said second switch means is in said second condition; and means controlled by said first switch means and controlling said second switch means to cause said second switch means to change from said first condition to said second condition whenever said transmitter is active and to revert said second switch means to said first condition whenever said transmitter is inactive.
Claim 5
Dependent Claim
79 words
The combination of claim 1 wherein said second switch means comprises a field effect transistor having an input electrode to which guidance signal from said receiver is applied, an output electrode for applying guidance signal to said utilizing means and a control electrode, said means controlling said second switch means biasing said control electrode for conduction between said input and output electrodes in said first condition and for non-conduction between said input and output electrodes in said second condition.
Claim 6
Dependent Claim
51 words
The combination of claim 2 wherein said storage means comprises a capacitor and a high input impedance amplifier, the input of said amplifier being connected to said transistor output electrode, the output of said amplifier being connected to said utilizing means, said capacitor also being connected to said transistor output electrode.
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 |