US3893772A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Installation for resetting a heading indicator
Assignee: Thales SA
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Filing: 1973-02-21
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Granted: 1975-07-08
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Expires: 1993-02-21
Abstract
Abstract In order to determine the azimuthal deviation between a reference direction and a heading indication given by an instrument aboard an aircraft, particularly for resetting that instrument before takeoff, a ground installation at an airport includes a radiation source emitting an outgoing laser beam which is periodically deflected by a land-based polygonal drum to sweep between predetermined boundaries in a horizontal plane. As the aircraft taxies across the deflection path of the laser beam, a mirror aboard that craft, retroreflective in a vertical plane, returns that beam toward the source at an instant whose time position within a deflection cycle is a measure of the azimuthal deviation to be ascertained. This deviation can be communicated to the craft by a frequency modulation of the outgoing laser beam detected by a monitoring photocell aboard the craft.
Inventors
- 👤 Tilly Henri Le
- 👤 Henri Robin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 06:11
CPC Classifications
G; G01; G01C; G01C23/00; G01C23/005; G01C25/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
185 words
A system for determining the azimuthal deviation between a reference direction and a heading indication given by an instrument aboard a craft moving over a surface area, comprising: land-based equipment including a source of radiation at the level of said surface area emitting an outgoing laser beam; sweep means in said equipment for periodically deflecting the outgoing laser beam between predetermined boundaries in a horizontal plane; a mirror retroreflective in a vertical plane and symmetrically reflective in a horizontal plane aboard said craft for returning said outgoing laser beam toward said source upon passage of said craft through the deflection path thereof with an azimuthal orientation making the returning beam coincident with the outgoing beam; timing means controlled by said sweep means for marking the start of a deflection cycle of said laser beam; detector means in said equipment for generating an output signal upon impingement thereon of a laser beam returned by said reflector means; and calculating means controlled by said timing means and said detector means for deriving said azimuthal deviation from the time position of said output signal within a deflection cycle.
Claim 2
Independent Claim
185 words
A system for determining the azimuthal deviation between a reference direction and a heading indication given by an instrument aboard a craft moving over a surface area, comprising: land-based equipment including a source of radiation at the level of said surface area emitting an outgoing laser beam; sweep means in said equipment for periodically deflecting the outgoing laser beam between predetermined boundaries in a horizontal plane; a mirror retroreflective in a vertical plane and symmetrically reflective in a horizontal plane aboard said craft for returning said outgoing laser beam toward said source upon passage of said craft through the deflection path thereof with an azimuthal orientation making the returning beam coincident with the outgoing beam; timing means controlled by said sweep means for marking the start of a deflection cycle of said laser beam; detector means in said equipment for generating an output signal upon impingement thereon of a laser beam returned by said reflector means; and calculating means controlled by said timing means and said detector means for deriving said azimuthal deviation from the time position of said output signal within a deflection cycle.
Claim 3
Dependent Claim
27 words
A system as defined in claim 1, further comprising receiving means for the impinging laser beam disposed aboard said craft adjacent said mirror in said vertical plane.
Claim 4
Dependent Claim
43 words
A system as defined in claim 2 wherein said receiving means is responsive to a predetermined laser frequency, further comprising modulating means for the outgoing laser beam in said equipment controlled by said calculating means for communicating said azimuthal deviation to the craft.
Claim 5
Dependent Claim
31 words
A system as defined in claim 3 wherein said modulating means is normally inoperative, said equipment further comprising monitoring means responsive to a returning laser beam for activating said modulating means.
Claim 6
Dependent Claim
30 words
A system as defined in claim 1 wherein said equipment includes optical means for substantially broadening the outgoing laser beam in a vertical direction as compared with its horizontal dimension.
Claim 7
Dependent Claim
30 words
A system as defined in claim 5 wherein said mirror has a serrated vertical profile defined by a succession of narrow horizontal reflector strips adjoining one another at right angles.
Claim 8
Dependent Claim
27 words
A system as defined in claim 1 wherein said sweep means comprises a rotary reflecting member with a multiplicity of angularly adjoining facets defining a regular polygon.
Claim 9
Dependent Claim
35 words
A system as defined in claim 7 wherein said timing means comprises a pulse generator actuatable by radiant energy from the outgoing laser beam upon reflection from a terminal portion of each of said facets.
Claim 10
Dependent Claim
79 words
A system as defined in claim 8 wherein said equipment includes a first partly reflective light-transmissive element interposed between said source and said reflecting member, and a second partly reflective light-transmissive element disposed in the deflection path of the outgoing beam beyond said reflecting member, said detector means including a first photocell positioned to intercept beam energy reflected by said first element, said pulse generator including a second photocell positioned to intercept beam energy reflected by said second element.
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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) | 1978-07-07 | 1979-01-06 | 1979-07-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-07 | 1983-01-06 | 1983-07-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-07 | 1987-01-06 | 1987-07-08 | $7700.00 | Window Closed / Lapsed |