US3696418A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Altitude measuring system
Assignee: National Aeronautics and Space Administration
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Filing: 1970-09-14
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Granted: 1972-10-03
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Expires: 1990-09-14
Abstract
Abstract A surface based altitude measuring system for accurately measuring the altitude of an airborne vehicle consisting in part of two antennas for producing narrow fan beams which intersect in space, so that the altitude of an aircraft which flies through the two beams can be accurately determined. The radar echo which returns from the aircraft determines the slant range of the aircraft from the antennas, and the time interval between the interceptions of the two beams by the aircraft is related to the elevation angle. The true height of the aircraft above the antennas is determined from the above measurements, with compensation for flight paths not directly above the facility.
Inventors
- 👤 George B Litchford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:39
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/06; G01S13/46; G01S1/00; G01S1/02
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
144 words
A system for determining the zenith angle of the line of flight of an aircraft over a reference location, comprising; first and second directive antennas, each having a fan-shaped directive pattern, located at the reference location and directed vertically upward, with their patterns intersecting in a region that extends vertically upward from the reference location, means for measuring and producing a representation of the time interval between the respective interceptions of the median planes of said directive patterns by the aircraft in its travel along said line of flight, means for measuring and producing a representation of the time interval during which the aircraft intercepts one of said beams, means for determining the quotient of said first interval representation divided by said second interval representation, and means for producing a representation of said quotient in terms of a specific function of said zenith angle.
Claim 2
Independent Claim
144 words
A system for determining the zenith angle of the line of flight of an aircraft over a reference location, comprising; first and second directive antennas, each having a fan-shaped directive pattern, located at the reference location and directed vertically upward, with their patterns intersecting in a region that extends vertically upward from the reference location, means for measuring and producing a representation of the time interval between the respective interceptions of the median planes of said directive patterns by the aircraft in its travel along said line of flight, means for measuring and producing a representation of the time interval during which the aircraft intercepts one of said beams, means for determining the quotient of said first interval representation divided by said second interval representation, and means for producing a representation of said quotient in terms of a specific function of said zenith angle.
Claim 3
Dependent Claim
19 words
The system as recited in claim 1 additionally comprising radar ranging means for determining slant range of the aircraft.
Claim 4
Dependent Claim
31 words
The system as recited in claim 2 additionally comprising computer means for combining the zenith angle and said slant range for determining the true height of the aircraft above the ground.
Claim 5
Dependent Claim
46 words
The system as recited in claim 1, wherein said means for measuring the said second time interval comprises a receiver coupled to one of said antennas, and means coupled to the output of the receiver for measuring the transit time of the aircraft in said beam.
References Cited (Backward Citations)
US3337869A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-03 | 1976-04-03 | 1976-10-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-03 | 1980-04-03 | 1980-10-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-03 | 1984-04-03 | 1984-10-03 | $7700.00 | Window Closed / Lapsed |