METHOD AND SYSTEM FOR PROCESSING POSITIONING SIGNALS IN A GEOMETRIC MODE

• US 20030016170A1
• Filed: 07/18/2001
• Published: 01/23/2003
• Est. Priority Date: 07/18/2001
• Status: Active Grant

• Current Assignee: Fast Location.Net, LLC
• Original Assignee: Fast Location.Net, LLC
• Inventors: Jandrell, Louis Henry Martin
• Granted Patent: US 6,515,620 B1
• Time in Patent Office: Days
• US Class Current: 342/357.12
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• CPC Class Codes: G01S 19/17 Emergency applications
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/254 relating to Doppler shift of satellite signals
• CPC Class Codes: G01S 19/256 relating to timing, e.g. time of week, code phase, timing offset
• 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 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G01S 19/35 Constructional details or hardware or software details of the signal processing chain
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 5/0018 Transmission from mobile station to base station
• CPC Class Codes: G01S 5/0063 of measured values, i.e. measurement on base station and position calculation on mobile

Abstract

A method for processing positioning signals in a ranging receiver in a geometric mode is provided. The method includes receiving timing information from a first set of satellites in a satellite constellation at the ranging receiver. The satellite constellation includes a plurality of satellites. A time of day is determined based on the received timing information. Approximate location data for the ranging receiver is determined. A frequency bias for the ranging receiver is determined. Ephemeris data is received from a second set of satellites in the satellite constellation. Superframe data for the satellite constellation is received from a third set of satellites in the satellite constellation at the ranging receiver. A pseudorange estimate is determined in the ranging receiver based on the time of day, the approximate location data, the frequency bias, the ephemeris data, and the superframe data.

Claims

1. A method for processing positioning signals in a ranging receiver in a geometric mode, comprising:

receiving timing information from a first set of satellites in a satellite constellation at the ranging receiver, the satellite constellation comprising a plurality of satellites;

determining a time of day based on the received timing information;

determining approximate location data for the ranging receiver;

determining a frequency bias for the ranging receiver;

receiving ephemeris data from a second set of satellites in the satellite constellation;

receiving superframe data for the satellite constellation from a third set of satellites in the satellite constellation at the ranging receiver; and

determining a pseudorange estimate in the ranging receiver based on the time of day, the approximate location data, the frequency bias, the ephemeris data, and the superframe data.

2. The method of claim 1, at least a portion of at least two of the first, second and third sets of satellites comprising the same satellites.

3. The method of claim 1, determining a time of day based on the received timing information comprising determining the time of day to within approximately one millisecond of a time of day for the satellite constellation.

4. The method of claim 1, the approximate location data comprising an estimate of a current location of the ranging receiver to within approximately one mile.

5. The method of claim 1, the approximate location data comprising a location estimate previously determined at the ranging receiver.

6. The method of claim 1, the approximate location data comprising general location information provided by a source external to the ranging receiver.

7. The method of claim 6, the general location information comprising a cell site identification.

8. The method of claim 1, the approximate location data comprising an estimate provided by a user of a wireless device comprising the ranging receiver.

9. The method of claim 1, determining a pseudorange estimate in the ranging receiver based on the time of day, the approximate location data, the frequency bias, the ephemeris data, and the superframe data comprising determining the pseudorange estimate based on ephemeris data received within approximately 24 hours and superframe data received within approximately 96 hours of the determination of the pseudorange estimate.

10. A system for processing positioning signals in a ranging receiver in a geometric mode, comprising:

a computer-processable medium; and

logic stored on the computer-processable medium, the logic operable to receive timing information from a first set of satellites in a satellite constellation at the ranging receiver, the satellite constellation comprising a plurality of satellites, to determine a time of day based on the received timing information, to determine approximate location data for the ranging receiver, to determine a frequency bias for the ranging receiver, to receive ephemeris data from a second set of satellites in the satellite constellation, to receive superframe data for the satellite constellation from a third set of satellites in the satellite constellation at the ranging receiver, and to determine a pseudorange estimate in the ranging receiver based on the time of day, the approximate location data, the frequency bias, the ephemeris data, and the superframe data.

11. The system of claim 10, at least a portion of at least two of the first, second and third sets of satellites comprising the same satellites.

12. The system of claim 10, the logic operable to determine the time of day based on the received timing information to within approximately one millisecond of a time of day for the satellite constellation.

13. The system of claim 10, the approximate location data comprising an estimate of a current location of the ranging receiver to within approximately one mile.

14. The system of claim 10, the approximate location data comprising a location estimate previously determined at the ranging receiver.

15. The system of claim 10, the approximate location data comprising general location information provided by a source external to the ranging receiver.

16. The system of claim 15, the general location information comprising a cell site identification.

17. The system of claim 10, the approximate location data comprising an estimate provided by a user of a wireless device comprising the ranging receiver.

18. The system of claim 10, the logic operable to determine the pseudorange estimate in the ranging receiver based on ephemeris data received within approximately 24 hours and superframe data received within approximately 96 hours of the determination of the pseudorange estimate.

20. The system of claim 19, at least a portion of at least two of the first, second and third sets of satellites comprising the same satellites.

21. The system of claim 19, the means for determining a time of day based on the received timing information comprising means for determining the time of day to within approximately one millisecond of a time of day for the satellite constellation.

22. The system of claim 19, the approximate location data comprising an estimate of a current location of the ranging receiver to within approximately one mile.

23. The system of claim 19, the approximate location data comprising a location estimate previously determined at the ranging receiver.

24. The system of claim 19, the approximate location data comprising general location information provided by a source external to the ranging receiver.

25. The system of claim 24, the general location information comprising a cell site identification.

26. The system of claim 19, the approximate location data comprising an estimate provided by a user of a wireless device comprising the ranging receiver.

27. The system of claim 19, the means for determining a pseudorange estimate in the ranging receiver based on the time of day, the approximate location data, the frequency bias, the ephemeris data, and the superframe data comprising means for determining the pseudorange estimate based on ephemeris data received within approximately 24 hours and superframe data received within approximately 96 hours of the determination of the pseudorange estimate.

29. The method of claim 28, the specified set of satellites determined based on geometric dilution of precision criteria.

30. The method of claim 28, the specified set of satellites determined based on elevation angle criteria.

31. The method of claim 28, determining a CFO comprising adding a frequency bias for the ranging receiver to the determined Doppler frequency shift.

32. The method of claim 28, compensating for time dilation comprising correlation peak shifting.

33. The method of claim 28, compensating for time dilation comprising vector rotation in a frequency domain during correlation by Fast Fourier Transform means.

34. The method of claim 28, compensating for time dilation comprising sample shifting.

35. The method of claim 28, determining a pseudorange comprising determining a pseudorange from stacked compensated signal samples accumulated over an interval in the range of approximately 1 to 30 seconds, the positioning signals comprising a minimum carrier-to-noise density ratio of approximately 5 dB to 10 dB.

37. The method of claim 36, obtaining a satellite identifier, a Doppler frequency shift, and a Doppler rate for each of a plurality of satellites comprising obtaining a satellite identifier, a Doppler frequency shift, and a Doppler rate for each of a plurality of satellites based on geometric prediction.

38. The method of claim 36, each message bit transition offset comprising a transit time for the positioning signals received from the corresponding satellite.

39. The method of claim 36, the specified number of message data bits determined by dividing a maximum number of samples by a number of samples per message data bit.

19. A system for processing positioning signals in a ranging receiver in a geometric mode, comprising:

means for receiving timing information from a first set of satellites in a satellite constellation at the ranging receiver, the satellite constellation comprising a plurality of satellites;

means for determining a time of day based on the received timing information;

means for determining approximate location data for the ranging receiver;

means for determining a frequency bias for the ranging receiver;

means for receiving ephemeris data from a second set of satellites in the satellite constellation;

means for receiving superframe data for the satellite constellation from a third set of satellites in the satellite constellation at the ranging receiver; and

means for determining a pseudorange estimate in the ranging receiver based on the time of day, the approximate location data, the frequency bias, the ephemeris data, and the superframe data.

28. A method for processing positioning signals in a ranging receiver in a geometric mode, comprising:

determining a Doppler frequency shift, a Doppler rate and a satellite identifier for each of a specified set of satellites, the satellites operable to transmit positioning signals, the positioning signals comprising, for each satellite, a Gold code and message data bits;

for each satellite, predicting message data bits to be transmitted by the satellite;

determining a carrier frequency offset (CFO) and a CFO rate for each satellite;

assigning the Doppler rate to the corresponding CFO rate for each satellite;

collecting a signal sample for processing;

complex multiplying the sample by each of a set of CFO compensation terms to generate a first result for each of the CFO compensation terms;

scalar multiplying each of the first results by a corresponding data bit polarity to generate a second result for each of the first results;

correlating each of a plurality of pseudorange stacks with the Gold code for a corresponding one of the satellites, the pseudorange stacks comprising the second results;

compensating each pseudorange stack for time dilation;

adding each pseudorange stack to an extended output stack;

determining whether a minimum number of adequate peaks exists in the extended output stack; and

determining a pseudorange based on the adequate peaks when the minimum number of adequate peaks exists in the extended output stack.

36. A method for removing message data modulation from positioning signals received at a ranging receiver, the positioning signals comprising pseudorange samples, the method comprising:

obtaining a satellite identifier, a Doppler frequency shift, and a Doppler rate for each of a plurality of satellites;

determining a message bit transition offset for each satellite;

determining a specified number of message data bits for each satellite;

compensating each of the pseudorange samples for carrier frequency offset; and

multiplying each of the compensated pseudorange samples by a corresponding stored message data bit value.

40. A system for removing message data modulation from positioning signals received at a ranging receiver, the positioning signals comprising pseudorange samples, the system comprising:

a computer-processable medium; and

logic stored on the computer-processable medium, the logic operable to obtain a satellite identifier, a Doppler frequency shift, and a Doppler rate for each of a plurality of satellites, to determine a message bit transition offset for each satellite, to determine a specified number of message data bits for each satellite, to compensate each of the pseudorange samples for carrier frequency offset, and to multiply each of the compensated pseudorange samples by a corresponding stored message data bit.

41. The system of claim 40, the logic operable to obtain a satellite identifier, a Doppler frequency shift, and a Doppler rate for each of a plurality of satellites based on geometric prediction.

42. The system of claim 40, each message bit transition offset comprising a transit time for the positioning signals received from the corresponding satellite.

43. The system of claim 40, the logic further operable to determine the specified number of message data bits by dividing a maximum number of samples by a number of samples per message data bit.

44. A system for removing message data modulation from positioning signals received at a ranging receiver, the positioning signals comprising pseudorange samples, the system comprising:

means for obtaining a satellite identifier, a Doppler frequency shift, and a Doppler rate for each of a plurality of satellites;

means for determining a message bit transition offset for each satellite;

means for determining a specified number of message data bits for each satellite;

means for compensating each of the pseudorange samples for carrier frequency offset; and

means for multiplying each of the compensated pseudorange samples by a corresponding stored message data bit.

45. The system of claim 44, the means for obtaining a satellite identifier, a Doppler frequency shift, and a Doppler rate for each of a plurality of satellites comprising means for obtaining a satellite identifier, a Doppler frequency shift, and a Doppler rate for each of a plurality of satellites based on geometric prediction.

46. The system of claim 44, each message bit transition offset comprising a transit time for the positioning signals received from the corresponding satellite.

47. The system of claim 44, the specified number of message data bits determined by dividing a maximum number of samples by a number of samples per message data bit.

49. The method of claim 48, receiving ephemeris data comprising receiving ephemeris data from a satellite information server.

50. The method of claim 48, receiving superframe data comprising receiving superframe data from a satellite information server.

51. The method of claim 48, the approximate location data comprising an estimate of a current location of the ranging receiver to within approximately one mile.

52. The method of claim 48, the approximate location data comprising a location estimate previously determined at the ranging receiver.

53. The method of claim 48, the approximate location data comprising general location information provided by a source external to the ranging receiver.

54. The method of claim 53, the general location information comprising a cell site identification.

48. A method for processing positioning signals in a ranging receiver in a geometric mode, the positioning signals received from a plurality of satellites in a satellite constellation, the method comprising:

receiving timing information from one of the satellites at the ranging receiver;

determining a time of day based on the received timing information;

determining approximate location data for the ranging receiver;

determining a frequency bias for the ranging receiver;

receiving ephemeris data;

receiving superframe data for the satellite constellation at the ranging receiver; and

determining a pseudorange estimate in the ranging receiver based on the time of day, the approximate location data, the frequency bias, the ephemeris data, and the superframe data.

55. A method for compensating for time dilation of positioning signals received at a ranging receiver, the positioning signals comprising pseudorange samples in a single epoch duration sub-stack of samples, during accumulation of the sub-stack into an output-stack, the method comprising:

determining a movement amount for each substack, the movement amount proportional to a Doppler frequency shift for the sub-stack and comprising a whole number of sample positions and a first fractional part of a sample position for the sample;

multiplying the sample value by the first fractional part to generate a first sample fragment;

subtracting the first fractional part from 1 to determine a second fractional part;

multiplying the sample value by the second fractional part to generate a second sample fragment;

adding the fragments of the sample being accumulated to each of two output-stack sample positions overlapped by the corresponding moved sample position based on the movement amount; and

adding the fragments of the sample being accumulated to each of two output-stack sample positions overlapped by the corresponding moved sample positions at the other end of the output-stack, when the movement amount implies a destination beyond the ends of the output-stack.

56. A method for processing positioning signals in a ranging receiver in a geometric mode, comprising:

receiving timing information from a first set of satellites in a satellite constellation at the ranging receiver, the satellite constellation comprising a plurality of satellites;

determining a time of day based on the received timing information to within approximately one millisecond of a time of day for the satellite constellation;

determining approximate location data for the ranging receiver, the approximate location data comprising an estimate of a current location of the ranging receiver to within approximately one mile;

determining a frequency bias for the ranging receiver;

receiving ephemeris data from a second set of satellites in the satellite constellation;

receiving superframe data for the satellite constellation from a third set of satellites in the satellite constellation at the ranging receiver, at least a portion of at least two of the first, second and third sets of satellites comprising the same satellites; and

determining a pseudorange estimate in the ranging receiver based on the time of day, the approximate location data, the frequency bias, and ephemeris data received within approximately 24 hours and superframe data received within approximately 96 hours of the determination of the pseudorange estimate.

57. A method for processing positioning signals in a ranging receiver in a geometric mode, comprising:

determining a Doppler frequency shift, a Doppler rate and a satellite identifier for each of a specified set of satellites, the satellites operable to transmit positioning signals, the positioning signals comprising, for each satellite, a Gold code and message data bits;

for each satellite, predicting message data bits to be transmitted by the satellite;

determining a carrier frequency offset (CFO) and a CFO rate for each satellite by adding a frequency bias for the ranging receiver to the determined Doppler frequency shift;

assigning the Doppler rate to the corresponding CFO rate for each satellite;

collecting a signal sample for processing;

complex multiplying the sample by each of a set of CFO compensation terms to generate a first result for each of the CFO compensation terms;

scalar multiplying each of the first results by a corresponding data bit polarity to generate a second result for each of the first results;

correlating each of a plurality of pseudorange stacks with the Gold code for a corresponding one of the satellites, the pseudorange stacks comprising the second results;

compensating each pseudorange stack for time dilation;

adding each pseudorange stack to an extended output stack;

determining whether a minimum number of adequate peaks exists in the extended output stack; and

determining a pseudorange based on the adequate peaks when the minimum number of adequate peaks exists in the extended output stack, the pseudorange determined from stacked compensated signal samples accumulated over an interval in the range of approximately 1 to 30 seconds, the positioning signals comprising a minimum carrier-to-noise density ratio of approximately 5 dB to 10 dB.

58. A method for removing message data modulation from positioning signals received at a ranging receiver, the positioning signals comprising pseudorange samples, the method comprising:

obtaining a satellite identifier, a Doppler frequency shift, and a Doppler rate based on geometric prediction for each of a plurality of satellites;

determining a message bit transition offset for each satellite, each message bit transition offset comprising a transit time for the positioning signals received from the corresponding satellite;

determining a specified number of message data bits for each satellite, the specified number of message data bits determined by dividing a maximum number of samples by a number of samples per message data bit;

compensating each of the pseudorange samples for carrier frequency offset; and

multiplying each of the compensated pseudorange samples by a corresponding stored message data bit.