SYSTEM AND/OR METHOD FOR REDUCING AMBIGUITIES IN RECEIVED SPS SIGNALS

• US 20080079633A1
• Filed: 08/21/2007
• Published: 04/03/2008
• Est. Priority Date: 08/23/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Farmer, Dominic, Pon, Rayman
• Granted Patent: US 7,817,084 B2
• Time in Patent Office: Days
• US Class Current: 342/357.12
• CPC Class Codes: G01S 19/243 Demodulation of navigation message
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data
• CPC Class Codes: G01S 19/33 Multimode operation in different systems which transmit time stamped messages, e.g. GPS/GLONASS

Abstract

The subject matter disclosed herein relates to a system and method for resolving ambiguities associated with signals received from space vehicles (SVs) in a satellite navigation system.

Claims

1. A method comprising:

associating first pseudorange hypotheses derived from a first signal acquired from a first space vehicle (SV) at a reference location with one or more second pseudorange hypotheses derived from a second signal received from said second SV at said reference location, said associating being based, at least in part, on an estimated difference between a first range to said first SV from said reference location and a second range to a second SV from said reference location; and

reducing an ambiguity of a phase of a bit edge of a data signal modulating said first signal based, at least in part, on said associated first pseudorange hypotheses.

2. The method of claim 1, and further comprising determining said estimated difference based, at least in part, on locations of said first and second SVs.

3. The method of claim 2, and further comprising receiving information indicative of locations of said first and second SVs are obtained from an acquisition assistance message.

4. The method of claim 1, wherein said second signal is encoded with a repeating data sequence, and wherein said method further comprises:

decoding said repeating data sequence from at least a portion of said received second signal; and

eliminating at least some of said second pseudorange hypotheses based, at least in part, on said decoded data sequence.

5. The method of claim 4, wherein said reducing said ambiguity further comprises:

limiting said associated first pseudorange hypotheses to first pseudorange hypotheses associated with any remaining second pseudorange hypotheses following said eliminating.

6. The method of claim 1, wherein said second signal is encoded with a known data sequence, and wherein said method further comprises:

detecting a phase alignment of said known data sequence relative to a true pseudorange to said second SV, and wherein said associating further comprises associating said true pseudorange to said second SV with said first pseudorange hypotheses.

7. The method of claim 1, wherein first SV comprises a satellite in a GPS constellation and said second SV comprises a satellite in a Galileo constellation.

8. A method comprising:

determining a plurality of first pseudorange hypotheses to a first space vehicle (SV) from a reference location based, at least in part, on a first code phase detected in a first signal received at said reference location, said first signal being modulated by a data signal; and

reducing an ambiguity associated with a true pseudorange among said first pseudorange hypotheses with respect to said data signal based, at least in part, on a second code phase detected in a second signal received from a second SV at said reference location.

9. The method of claim 8, wherein said second signal is encoded with a periodically repeating random code sequence, and wherein said reducing said ambiguity further comprises:

determining one or more second pseudorange hypotheses to said second SV from said reference location based, at least in part, on said second code phase; and

associating said first hypotheses with said second hypotheses.

10. The method of claim 9, wherein said associating said first hypotheses with said second hypotheses further comprises associating said first hypotheses with said second hypotheses based, at least in part, on an estimate of a difference between a range to said first SV from said reference location and a range to said second SV from said reference location.

11. The method of claim 10, wherein said estimate is based, at least in part, on locations of said SVs.

12. The method of claim 9, wherein said second signal is modulated with information, and wherein said reducing said ambiguities further comprises eliminating hypotheses associated with said phase changes based, at least in part, on said information.

13. The method of claim 12, wherein said information signal comprises a periodically repeating data sequence.

14. The method of claim 13, wherein said information signal comprises a Galileo pilot channel.

15. The method of claim 8, wherein said first signal is transmitted according to a first GNSS and second signal is transmitted according to a second GNSS different from said first GNSS.

16. The method of claim 15, wherein said first SV is of a GPS constellation and said second SV is of a Galileo constellation.

17. A method comprising:

receiving a first space vehicle (SV) signal from a first satellite positioning system; and

reducing a bit edge ambiguity of a data signal modulating a second SV signal received from a second satellite positioning system based, at least in part, on information in said received first SV signal.

18. The method of claim 17, wherein said information comprises a code phase detected in said first SV signal.

19. The method of claim 18, wherein said reducing said bit edge ambiguity further comprises:

determining one or more first pseudorange hypotheses based, at least in part, on said code phase; and

associating said one or more first pseudorange hypotheses with a plurality of second pseudorange hypotheses associated with said second SV signal.

20. An article comprising:

a storage medium, said storage medium comprising machine-readable instructions stored thereon which, if executed by a computing platform, are adapted to cause said computing platform to;

associate first pseudorange hypotheses derived from a first signal acquired from a first space vehicle (SV) at a reference location with one or more second pseudorange hypotheses derived from a second signal received from a second SV at said reference location, said association between said first and second pseudorange hypotheses being based, at least in part, on an estimated difference between a first range to said first SV from said reference location and a second range to said second SV from said reference location; and

reduce an ambiguity of a phase of a bit edge of a data signal modulating said first signal based, at least in part, on said associated first pseudorange hypotheses.

21. An article comprising:

a storage medium, said storage medium comprising machine-readable instructions stored thereon which, if executed by a computing platform, are adapted to cause said computing platform to;

determine a plurality of first pseudorange hypotheses to said first space vehicle (SV) from a reference location based, at least in part, on a first code phase detected in a first signal received at said reference location, said first signal being modulated by a data signal; and

reduce an ambiguity associated with a true pseudorange among said first pseudorange hypotheses with respect to said data signal based, at least in part, on a second code phase detected in a second signal received from a second SV at said reference location.

22. An article comprising:

a storage medium, said storage medium comprising machine-readable instructions stored thereon which, if executed by a computing platform, are adapted to cause said computing platform to;

obtain information based, at least in part, on a first space vehicle (SV) signal received from a first satellite positioning system; and

reduce a bit edge ambiguity of a data signal modulating a second SV signal received from a second satellite positioning system based, at least in part, on information in said received first SV signal.

23. A subscriber unit comprising:

a receiver to receive an acquisition assistance (AA) message comprising information indicative of locations of first and second space vehicles (SVs), said subscriber unit being adapted to;

estimate a difference between a first range to said first SV from a reference location and a second range to said second SV from said reference location based, at least in part, on said information;

associate, based at least in part on said estimated difference, first pseudorange hypotheses derived from a first signal acquired from said first SV at a reference location with one or more second pseudorange hypotheses derived from a second signal acquired from said second SV at said reference location; and

reduce an ambiguity of a phase of a bit edge of a data signal modulating said first signal based, at least in part, on said associated first pseudorange hypotheses.

24. The subscriber unit of claim 23, wherein said subscriber unit is further adapted to receive said AA message over a terrestrial wireless communication link.

25. A subscriber unit comprising:

a receiver to receive an acquisition assistance (AA) message comprising information indicative of locations of first and second space vehicles (SVs), said subscriber unit being adapted to;

determine a plurality of first pseudorange hypotheses based, at least in part, on a first code phase detected in said first signal, said first signal being modulated by a data signal; and

reduce an ambiguity associated with a true pseudorange among said first pseudorange hypotheses with respect to said data signal based, at least in part, on said information and a second code phase detected in said second signal.

26. The subscriber unit of claim 25, wherein said subscriber unit is further adapted to receive said AA message over a terrestrial wireless communication link.

27. A subscriber unit comprising:

a receiver to receive an acquisition assistance (AA) message comprising information indicative of locations of first and second space vehicle (SVs), said subscriber unit being adapted to;

receive said first and second SV signals; and

reduce a bit edge ambiguity of a data signal modulating said second received SV signal based, at least in part, on information in said received first SV signal and said information indicative of said locations.

28. The subscriber unit of claim 27, wherein said subscriber unit is further adapted to receive said AA message over a terrestrial wireless communication link.

29. A system comprising:

a position determination entity (PDE); and

a subscriber unit, the subscriber unit being adapted to;

receive an acquisition assistance (AA) message from said PDE over a terrestrial wireless communication link, said AA message comprising information indicative of locations of first and second space vehicles (SVs);

estimate a difference between a first range from a reference location to said first SV and a second range from said reference location to said second SV based, at least in part, on said information;

associate, based at least in part on said estimated difference, first pseudorange hypotheses derived from a first signal acquired from said first SV at a reference location with one or more second pseudorange hypotheses derived from a second signal received from said second SV at said reference location based; and

reduce an ambiguity of an alignment of a true pseudorange to said first SV relative to a bit edge of a data signal modulating said first signal based, at least in part, on said associated first pseudorange hypotheses.

30. A system comprising:

a position determination entity (PDE); and

a subscriber unit, the subscriber unit being adapted to;

receive an acquisition assistance (AA) message from said PDE over a terrestrial wireless communication link, said AA message comprising information indicative of locations of first and second space vehicles (SVs);

determine a plurality of first pseudorange hypotheses to said first space vehicle (SV) from said reference location based, at least in part, on a first code phase detected in a first signal received at said reference location, said first signal being modulated by a data signal; and

reduce an ambiguity associated with an alignment of a true pseudorange among said first pseudorange hypotheses with respect to said data signal based, at least in part, on a second code phase detected in a second signal received from a second SV at said reference location.

31. A system comprising:

a position determination entity (PDE); and

a subscriber unit, the subscriber unit being adapted to;

receive an acquisition assistance (AA) message from said PDE over a terrestrial wireless communication link, said AA message comprising information indicative of locations of first and second space vehicles (SVs), said first SV being from a first satellite positioning system (SPS) and a second SV being from a second SPS;

receive a first SV signal from said first SV and a second SV signal from said second SV; and

reduce a bit edge ambiguity of a data signal modulating said second received SV signal based, at least in part, on information in said first received SV signal and said information indicative of said locations of said first and second SVs.

32. A method comprising:

acquiring a first navigation signal at a reference location;

estimating timing of a bit edge of a data signal modulating a second navigation signal received at said reference location; and

performing pre-detection integration to acquire said second navigation signal over an interval of said second navigation signal based, at least in part, on said estimated timing of said bit edge.

33. The method of claim 32, wherein said first navigation signal is transmitted by a first space vehicle (SV) and said second navigation signal is transmitted by a second SV, wherein said bit edge is synchronized with a known instance of said first navigation signal, and wherein said estimating said timing of said bid edge further comprises associating said known instance with said bit edge based, at least in part, on an estimated difference between a first range to said first SV from said reference location and a second range to a second SV from said reference location.

34. The method of claim 32, wherein said estimating said timing of said bit edge further comprises:

decoding an alternating viterbi encoded signal modulating said first navigation signal; and

associating a transition of said decoded alternating viterbi encoded signal with said bit edge.

35. The method of claim 32, wherein said estimating said timing of said bit edge further comprises:

decoding a repeating data sequence modulating said first navigation signal; and

associating said bit edge in said second signal with an instance of said decoded data sequence.

36. The method of claim 32, wherein said first navigation signal is transmitted from a space vehicle (SV) that is a member of a Galileo constellation and said second navigation signal is transmitted from an SV that is a member of a GPS constellation.

37. A method comprising:

determining timing of a bit edge of a data signal modulating a first navigation signal received at a reference location; and

determining timing of transitions in an alternating viterbi encoded signal modulating a second navigation signal received at said reference location based, at least in part, on said timing of said bit edge.

38. The method of claim 37, wherein said first navigation signal is transmitted by a first space vehicle (SV) and said second navigation signal is transmitted by a second SV, and wherein said determining said timing of said transitions further comprises associating said timing of said bit edge with said timing of said transitions based, at least in part, on an estimated difference between a first range to said first SV from said reference location and a second range to a second SV from said reference location.

39. The method of claim 38, wherein said first SV is a member of a GPS constellation and said second SV is a member of a Galileo constellation.