US3908189A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Airborne radar instrument landing system
Assignee: Individual
•
Filing: 1973-06-27
•
Granted: 1975-09-23
•
Expires: 1993-06-27
Abstract
Abstract An ILS (instrument landing system) utilizing a modified weather radar system of the aircraft and a retrodirective antenna located at the touchdown point and modulated so as to generate conventional guidance commands (fly up/fly down and fly right/fly left) signals from signal processing of the video output of the weather radar aboard the aircraft.
Inventors
- 👤 Walter E Buehler
- 👤 Clarence D Lunden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:10
CPC Classifications
H; H01; H01Q; H01Q3/00; H01Q3/44; H01Q3/46; G; G01; G01S; G01S13/00; G01S13/74; G01S13/75; G01S13/751; G01S13/756; G01S13/88; G01S13/91; G01S13/913
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
181 words
A microwave guidance system for landing an airplane comprising in combination: ground-based reflector means; an airplane based weather radar receiver and transmitter, said receiver including a sensitivity time contrOl circuit adjusted to provide a sensitivity proportional to range 4, said transmitter providing pulsed continuous wave energy for illuminating said ground based reflector means; said ground based reflector means including means for tone modulating said pulsed continuous wave energy at a plurality of audio frequencies; means coupled to said weather radar receiver for detecting the relative amplitudes of said tone modulated pulsed continuous wave energy at said plurality of audio frequencies and indicating the deviation of the airplane from flight path; and further including: gate generator means in said receiver for generating an adjustable ramp referenced to the main pulse from said transmitter; means for locking said gate generator on the reflected signal; means for deriving an enabling gate pulse from the signal locked gate of said gate generator means; and means for coupling said derived enabling gate pulse to I.F. stage of said receiver thereby providing reduction of ground clutter interference.
Claim 2
Dependent Claim
181 words
A microwave guidance system for landing an airplane comprising in combination: ground-based reflector means; an airplane based weather radar receiver and transmitter, said receiver including a sensitivity time contrOl circuit adjusted to provide a sensitivity proportional to range 4, said transmitter providing pulsed continuous wave energy for illuminating said ground based reflector means; said ground based reflector means including means for tone modulating said pulsed continuous wave energy at a plurality of audio frequencies; means coupled to said weather radar receiver for detecting the relative amplitudes of said tone modulated pulsed continuous wave energy at said plurality of audio frequencies and indicating the deviation of the airplane from flight path; and further including: gate generator means in said receiver for generating an adjustable ramp referenced to the main pulse from said transmitter; means for locking said gate generator on the reflected signal; means for deriving an enabling gate pulse from the signal locked gate of said gate generator means; and means for coupling said derived enabling gate pulse to I.F. stage of said receiver thereby providing reduction of ground clutter interference.
References Cited (Backward Citations)
US2604621A
Cited
US2871470A
Cited
US3181153A
Cited
US3648285A
Cited
US3671967A
Cited
US3716855A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-22 | 1979-03-24 | 1979-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-22 | 1983-03-24 | 1983-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-22 | 1987-03-24 | 1987-09-23 | $7700.00 | Window Closed / Lapsed |