Apparatus and method for determining whether a vehicle is located in a spot beam

• US 6,202,317 B1
• Filed: 07/30/1999
• Issued: 03/20/2001
• Est. Priority Date: 07/30/1999
• Status: Expired due to Term

• Current Assignee: Rockwell Collins, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Rockwell Collins, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Mueggenberg, Craig P.
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): Guadalupe, Yaritza
• Application Number:
  US09/364,386
• Time in Patent Office: 599 Days
• Field of Search: 33/1.A, 33/1.CC, 336/13, 33/1.SB, 33/1.SD, 33/1.SA, 702/150, 702/152, 702/166, 702/401, 702/144, 702/404
• US Class Current: 33/613
• CPC Class Codes: H04B 7/1855 using a telephonic control signal, e.g. propagation delay variation, Doppler frequency variation, power variation, beam identification

Abstract

A method and apparatus for determining the inclusion or exclusion of a current position of an aircraft within a satellite communication spot beam, which uses a technique of slightly moving the position being checked for inclusion, when it is determined that a ray drawn from the current position is coextensive with an endpoint of any line segment making up a boundary of the spot beam.

Claims

1. A method for determining the inclusion of a predetermined position within a polygon, comprising the steps of:

generating a reference line from the predetermined position to some position known to be outside of the polygon;

making an intersection determination if one of a plurality of line segments, forming a boundary of the polygon, has an endpoint which is along the reference line;

moving the predetermined position to a displaced location, in response to said intersection determination; and

,

repeating a predetermined process for determination of inclusion of the displaced location in the polygon.

2. A method of claim 1 wherein said predetermined position is a current position of an aircraft.

3. A method of claim 2 wherein said current position is generated by a GPS receiver.

4. A method of claim 1 wherein said reference line is drawn to infinity.

5. A method of claim 1, wherein said reference line is drawn to a Pole of the earth.

6. A method of claim 5 wherein said Pole of the earth is the North Pole.

7. A method of claim 6 wherein said displaced location is less than 5 degrees from the current position.

8. A method of claim 7 wherein said displaced location is less than 1 degree from the current position.

9. A method of claim 8 wherein said predetermined process involves counting a number of times the reference line crosses any of said plurality of line segments.

10. A method of determining inclusion of a position of an aircraft within a satellite communication spot beam, comprising the steps of:

defining the spot beam as a plurality of adjacent line segments forming a polygon, where each line segment has two vertices;

determining, for each line segment, whether such segment has both of said vertices on a single side of a reference ray drawn from the position to a known position outside of the spot beam;

for those segments not having both vertices on a single side of said reference ray, determining if any of said vertices are on said reference ray;

if any segment has a vertex on the reference ray, then the position is moved to a displaced location, and then returning to said step of determining,

if no segment has a vertex on the reference ray then, a point of intersection is calculated for each segment through which the ray is drawn;

generating a total number representative of a number of said points of intersection; and

,

determining whether said total number is even.

11. A method of claim 10 wherein said reference ray is drawn to a North Pole.

12. A method of claim 11 wherein a displaced position is a predetermined distance from said position.

13. A method of claim 12 where said predetermined distance is less than 0.001 radians.

14. A method of claim 13 wherein said predetermined distance is substantially negligible with respect to a rounding characteristic of computations of positions associated with said spot beam.

15. An apparatus for satellite communication by an aircraft in a spot beam, the apparatus comprising;

means for determining a current position of an aircraft during flight;

means for executing computer code;

executable computer code means which performs a function of determining an inclusion characteristic of said current position with respect to a spot beam, where said computer code means is responsive to a determination of whether a ray drawn from the current position to a known point outside of the spot beam is coextensive with a vertex of a line segment defining a polygon boundary which is representative of a boundary characteristic of the spot beam, and the limitation—

and where said executable code means is responsive to a displacement of said current position to a displaced location.

16. An apparatus of claim 15 wherein said means for determining a current position of said aircraft is a GPS receiver on said aircraft.

17. An apparatus of claim 16 wherein said means for executing computer code is a microprocessor.

18. An apparatus of claim 17 wherein said executable code means performs a function of tallying a number of intersections of said ray with said polygon boundary.

19. An apparatus of claim 18 wherein said executable code performs a function of determining whether said number of intersections is even.