US4050069A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transponder based landing system
Assignee: United States Department of the Army
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Filing: 1976-09-02
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Granted: 1977-09-20
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Expires: 1996-09-02
Abstract
Abstract An air traffic control system wherein a ground based interrogator/receivernterrogates an aircraft transponder which, in addition to responding to the interrogation, also transmits automatic encoded altitude information. The interrogator/receiver unit processes the received signal to derive relative azimuth and range information of the interrogated aircraft and to decode the altitude information to provide the aircraft reported altitude signal. The aircraft reported altitude signal is compared to the selected glide path height which is a function of the range that the approaching aircraft is from the runway touchdown point. The difference is noted on a glide scope meter. By observing the azimuth and range readings, and also the deflection from zero on the glide scope meter, the controller will be able to inform the aircraft pilot of the approaching aircraft position relative to runway center line, glide path and distance from touchdown.
Inventors
- 👤 Henry Schlussler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:50
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/74; G01S13/76; G01S13/765; G01S13/88; G01S13/91; G01S13/913
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
223 words
A landing approach system for aircraft having a transponder which includes means for automatically transmitting encoded altimeter information when said aircraft transponder is interrogated, said system comprising: a ground based interrogator/receiver unit for interrogating said aircraft transponder and adapted to receive response signals therefrom including said encoded altimeter information, the electronic center of said land based transponder antenna being aligned with the center line of a prescribed landing runway; means in circuit with said ground based unit for processing said response signal for respectively determining the azimuth of said aircraft relative to said runway, and the range of said aircraft to the point of touchdown on said runway; means in circuit with said ground based unit for decoding said encoded altimeter information to produce signals corresponding to the elevation reported from said aircraft; means responsive to the output of said range determining means for generating signals corresponding to a ground distance and a vertical approach path for said aircraft whereby a glide path for said aircraft is prescribed, said vertical approach path signals being a fixed proportion of said ground distance signals; and means for comparing said vertical approach path signals with said aircraft elevation reported signals to produce error signals corresponding to the difference therebetween; said azimuth, range and error signals comprising the information for guiding said aircraft along said glide path.
Claim 2
Dependent Claim
223 words
A landing approach system for aircraft having a transponder which includes means for automatically transmitting encoded altimeter information when said aircraft transponder is interrogated, said system comprising: a ground based interrogator/receiver unit for interrogating said aircraft transponder and adapted to receive response signals therefrom including said encoded altimeter information, the electronic center of said land based transponder antenna being aligned with the center line of a prescribed landing runway; means in circuit with said ground based unit for processing said response signal for respectively determining the azimuth of said aircraft relative to said runway, and the range of said aircraft to the point of touchdown on said runway; means in circuit with said ground based unit for decoding said encoded altimeter information to produce signals corresponding to the elevation reported from said aircraft; means responsive to the output of said range determining means for generating signals corresponding to a ground distance and a vertical approach path for said aircraft whereby a glide path for said aircraft is prescribed, said vertical approach path signals being a fixed proportion of said ground distance signals; and means for comparing said vertical approach path signals with said aircraft elevation reported signals to produce error signals corresponding to the difference therebetween; said azimuth, range and error signals comprising the information for guiding said aircraft along said glide path.
Claim 3
Dependent Claim
18 words
The landing approach system in accordance with claim 1 wherein said last mentioned means comprises a difference amplifier.
Claim 4
Dependent Claim
52 words
The landing approach system in accordance with claim 1 wherein said vertical approach path signals are developed across a voltage dividing network having two series connected resistors, said fixed proportion of said ground distance signals being in the ratio of one of said resistors divided by the sum of said two resistors.
Claim 5
Dependent Claim
39 words
The landing approach system in accordance with claim 3 wherein said resistors are R1 and R2, and said vertical approach path signals equal kd where d is the distance of said aircraft from touchdown point and k = (R2/R1+R2).
Claim 6
Dependent Claim
34 words
The landing approach system in accordance with claim 2 wherein one input to said difference amplifier is said decoded altimeter signals and a second input to said difference amplifier is said vertical approach signals.
Claim 7
Dependent Claim
29 words
The landing approach system in accordance with claim 2 wherein said vertical approach path signals are developed across a voltage dividing network having two series-connected resistors R1 and R2.
Claim 8
Dependent Claim
32 words
The landing approach system in accordance with claim 6 wherein said vertical approach path signals equal kd where d is the distance of said aircraft from touchdown point and k = (R1/R1+R2).
Claim 9
Dependent Claim
29 words
The landing approach system in accordance with claim 5 wherein said vertical approach path signals are developed across a voltage dividing network having two series-connected resistors R1 and R2.
Claim 10
Dependent Claim
32 words
The landing approach system in accordance with claim 8 wherein said vertical approach path signals equal kd where d is the distance of said aircraft from touchdown point and k = (R1/R1+R2).
Claim 11
Dependent Claim
25 words
The landing approach system in accordance with claim 4 wherein the glide path angle relative to said landing runway is θ = tan -1 K.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-09-19 | 1981-03-21 | 1981-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-19 | 1985-03-21 | 1985-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-19 | 1989-03-21 | 1989-09-20 | $7700.00 | Window Closed / Lapsed |