Culled satellite ephemeris information based on accurate distance in range calculations, for quick, accurate assisted locating satellite location determination

• US 7,183,973 B2
• Filed: 03/16/2005
• Issued: 02/27/2007
• Est. Priority Date: 10/15/2004
• Status: Expired due to Fees

• Current Assignee: TeleCommunication Systems Inc (Comtech Telecommunications Corporation)
• Original Assignee: TeleCommunication Systems Inc (Comtech Telecommunications Corporation)
• Inventors: Pitt, Lance Douglas, Lamprecht, Leslie Johann, Martin, Jeffrey Thomas
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Mull, Fred H
• Application Number:
  US11/080,517
• Publication Number:
  US 20060082498A1
• Time in Patent Office: 713 Days
• Field of Search: 342/357.15, 342/357.09
• US Class Current: 342/357.42
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
• CPC Class Codes: G01S 19/28 Satellite selection

Abstract

Locating satellites (e.g., GPS) are culled into a preferred group having a longest dwell time based on a time passing through an ellipsoid arc path through a cone of space, and communicated to mobile devices within a particular region (e.g., serviced by a particular base station). The culled locating satellites may select those visible, or more preferably those locating satellites currently within a cone of space above the relevant base station are selected for communication by a mobile device within the service area of the base station. Alternatively, a minimum set of locating satellites may be selected based on, e.g., being not only within an arbitrary cone of space normal to the base station, but also projected to remain within that cone of space for the longest period of time, i.e., having the longest dwell time, based on a calculated ellipsoid arc path through a cone of space.

Claims

1. A method of culling a plurality of locating satellites into a sub-plurality for communication, comprising:

calculating an ellipsoid arc path of each of said plurality of locating satellites that will pass within range of a given site to be located; and

culling said plurality of locating satellites to determine which of said plurality of locating satellites will be within range of said given site for a longest time based on said calculated ellipsoid arc path of each of said plurality of locating satellites.

2. The method of culling a plurality of locating satellites into a sub-plurality for communication according to claim 1, further comprising:

calculating a distance of said ellipsoid arc path of each of said plurality of locating satellites between the sides of an imaginary inverted conical shape between Earth and space normal thereto.

3. The method of culling a plurality of locating satellites into a sub-plurality for communication according to claim 2, further comprising:

calculating a time for each of said plurality of locating satellites to traverse said calculated distance.

4. The method of culling a plurality of locating satellites into a sub-plurality for communication according to claim 1, wherein:

said culling is performed by said wireless device.

5. The method of culling a plurality of locating satellites into a sub-plurality for communication according to claim 1, wherein:

said culling is performed by a base station with which said wireless device is in communication.

6. The method of culling a plurality of locating satellites into a sub-plurality for communication according to claim 1, wherein each of said plurality of locating satellites comprise:

a Global Positioning Satellite (GPS).

7. A method of culling a plurality of locating satellites into a sub-plurality for communication comprising:

calculating an ellipsoid arc path of each of said plurality of locating satellites that will pass within range of a given site to be located;

culling said plurality of locating satellites to determine which of said plurality of locating satellites will be within range of said given site for a longest time based on said calculated ellipsoid arc oath of each of said plurality of locating satellites;

calculating a distance of said ellipsoid arc oath of each of said plurality of locating satellites between the sides of an imaginary inverted conical shape between Earth and space normal thereto;

calculating a time for each of said plurality of locating satellites to traverse said calculated distance; and

determining a change in speed component of each of said plurality of locating satellites based on a point of a respective orbit of said locating satellite with respect to Earth.

8. The method of culling a plurality of locating satellites to a sub-plurality for communication according to claim 7, wherein:

a speed component of each of said plurality of locating satellites increases across said calculated distance when said locating satellites traverses said distance in an orientation of its orbit heading away from Earth; and

a speed component of each of said plurality of locating satellites decreases across said calculated distance when said locating satellite traverses said distance in an orientation of its orbit heading toward Earth.

9. Apparatus for culling a plurality of locating satellites into a sub-plurality for communication, comprising:

means for calculating an ellipsoid arc path of each of said plurality of locating satellites that will pass within range of a wireless device to be located; and

means for culling said plurality of locating satellites to determine which of said plurality of locating satellites will be within range of said wireless device for a longest time based on said calculated ellipsoid arc path of each of said plurality of locating satellites.

10. The apparatus for culling a plurality of locating satellites into a sub-plurality for communication according to claim 9, wherein:

said means for calculating calculates a distance of said ellipsoid arc path through the sides of an imaginary inverted conical shape between Earth and space normal thereto.

11. The apparatus for culling a plurality of locating satellites into a sub-plurality for communication according to claim 9, further comprising:

means for calculating a time for said locating satellite to traverse said calculated distance.

12. The apparatus for culling a plurality of locating satellites to a sub-plurality for communication according to claim 11, further comprising:

means for determining a change in speed component of said locating satellite based on a point of a respective orbit of said locating satellite with respect to Earth.

13. The apparatus for culling a plurality of locating satellites to a sub-plurality for communication according to claim 12, wherein:

a speed component of said locating satellite increases across said calculated distance when said locating satellite traverses said distance in an orientation of its orbit heading away from Earth; and

a speed component of said locating satellite decreases across said calculated distance when said locating satellite traverses said distance in an orientation of its orbit heading toward Earth.

14. The apparatus for culling a plurality of locating satellites into a sub-plurality for communication according to claim 9, wherein said plurality of locating satellites comprise:

Global Positioning Satellites (GPS).

15. The apparatus for culling a plurality of locating satellites into a sub-plurality for communication according to claim 9, wherein:

said means for culling is comprised in said wireless device.

16. The apparatus for culling a plurality of locating satellites into a sub-plurality for communication according to claim 9, wherein:

said means for culling is comprised in a base station with which said wireless device is in communication.